WO2022030305A1

WO2022030305A1 - Film for reinforcement, optical member and electronic member

Info

Publication number: WO2022030305A1
Application number: PCT/JP2021/027752
Authority: WO
Inventors: 翔悟佐々木; 千尋舟木
Original assignee: 日東電工株式会社
Priority date: 2020-08-06
Filing date: 2021-07-27
Publication date: 2022-02-10
Also published as: JP2022030292A; CN116034027A; KR20230047163A; TW202212126A

Abstract

The present invention provides a film for reinforcement, which exhibits easy separability in the initial stage after bonding to an adherend, while being capable of greatly increasing the adhesive force thereafter, and which exhibits recovery from bending and bending retainability. This film for reinforcement is provided with an adhesive layer. The adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) contains a monomer unit that has a polyorganosiloxane skeleton and a (meth)acrylic monomer unit. The adhesive layer has a surface elastic modulus of from 1 to 20 kPa at 23°C. In addition, the polymer (B) has a glass transition temperature T_B of from -20°C to 5°C.

Description

Reinforcing film, optical and electronic components

The present invention relates to a reinforcing film, and an optical member and an electronic member to which the reinforcing film is attached. This application claims priority under Japanese Patent Application No. 2020-134188 filed on August 6, 2020, the entire contents of which are incorporated herein by reference.

The adhesive is in the form of an adhesive sheet, and is used for mobile electronic devices such as mobile phones, smartphones, tablet personal computers, and other electronic devices for the purpose of adhering adherends to each other and fixing articles to the adherend. Widely used in various applications. For example, an adhesive sheet is used as a reinforcing material (reinforcing film) that imparts rigidity and impact resistance to optical members, electronic members, and the like constituting the above equipment.

Patent Documents

1 and 2 are examples of documents disclosing this type of prior art.

Further, in recent years, portable electronic devices that can be bent and rolled have attracted attention, and flexible devices (typically, image display devices such as organic EL and liquid crystal display devices) built in such electronic devices have been attracting attention. Development of an adhesive sheet that can be used for fixing or the like is in progress (Patent Documents 3 to 6).

On the other hand, looking at the performance of adhesives, recently, an adhesive sheet has been proposed which exhibits low adhesive strength at the initial stage of attachment to an adherend and then can greatly increase the adhesive strength (Patent Documents). 7). According to the adhesive sheet having such characteristics, before the increase in the adhesive force, the adhesive sheet exhibits re-sticking property (reworkability) useful for suppressing a decrease in yield due to an error or failure to attach the adhesive sheet, and also has an adhesive force. After rising, it is possible to exhibit strong adhesiveness suitable for the original purpose of use of the adhesive sheet.

Japanese Patent No. 6366199 Japanese Patent No. 6366200 Japanese Patent No. 6376271 Gazette Japanese Patent Application Publication No. 2016-108555 Japanese Patent Application Publication No. 2017-0956557 Japanese Patent Application Publication No. 2017-096559 Japanese Patent No. 6373458

The reinforcing film can also be used for the above flexible device. For example, in the manufacture of the above flexible device, since the members constituting the device are often thin, an adhesive sheet is attached as a reinforcing film to reinforce the device to prevent problems caused by deformation of the device. It is desirable to improve the handleability. Since the flexible device can be repeatedly bent or bent, the reinforcing film used for the flexible device has a property of recovering a normal shape (bending recovery property) even when repeatedly bent, and is peeled off. It is required to have characteristics (bending holding force) that do not cause problems such as. Since the reinforcing film having such bending recovery and bending holding force can be used for various applications including flexible devices, the range of application is not limited and it is useful.

For example, when a pressure-sensitive adhesive as proposed in Patent Document 7, which exhibits low adhesive strength at the initial stage of application and is configured to have a large increase in adhesive strength thereafter, is also used as a reinforcing film. It is desirable to have bending recovery and bending holding power. As a method for improving the bending holding force, for example, a method of appropriately setting the storage elastic modulus of the pressure-sensitive adhesive can be considered. However, in a pressure-sensitive adhesive designed to increase the adhesive strength as described above, changing the storage elastic modulus affects both the initial low adhesive strength and the post-increased adhesive strength. Further, considering the bending recovery in addition to the bending holding force, it is not easy to satisfy all of these characteristics. It would be practically beneficial to be able to improve the bending recovery and bending holding power of a pressure-sensitive adhesive that exhibits low adhesive strength at the initial stage of application and then greatly increases the adhesive strength.

The present invention was created in view of the above circumstances, and exhibits light peelability at the initial stage of attachment to the adherend, and then can greatly increase the adhesive strength and recover from bending. It is an object of the present invention to provide a reinforcing film having properties and bending holding force. Another object of the present invention is to provide an optical member and an electronic member to which the reinforcing film is attached.

According to the present specification, a reinforcing film provided with an adhesive layer is provided. The pressure-sensitive adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) contains a monomer unit having a polyorganosiloxane skeleton and a (meth) acrylic monomer unit. Further, the pressure-sensitive adhesive layer has a surface elastic modulus of 1 to 20 kPa at 23 ° C. Further, the glass transition temperature TB of the polymer ( _B ) is −20 ° C. to 5 ° C.

According to the above configuration, since the pressure-sensitive adhesive layer contains the polymer (A) and the polymer (B) containing a monomer unit having a polyorganosiloxane skeleton, it has a light peelability at the initial stage of being attached to the adherend. After that, it is possible to greatly increase the adhesive strength. Further, when the glass transition temperature (Tg) TB of the polymer ( _B ) is −20 ° C. or higher, the light peelability at the initial stage of application tends to be excellent, and when the _TB is 5 ° C. or lower, the adhesiveness tends to be excellent. It tends to have excellent force-increasing properties. Further, the reinforcing film has bending recovery property and bending holding force. Specifically, the reinforcing film having a surface elastic modulus (23 ° C. surface elastic modulus) at 23 ° C. of the pressure-sensitive adhesive layer is 1 kPa or more, and has good bending recovery while exhibiting the above-mentioned adhesive properties. Further, since the adhesive layer has a surface elastic modulus at 23 ° C. of 20 kPa or less, it has a good bending holding force while exhibiting the above-mentioned adhesive characteristics, so that even when it is used in a mode of repeated bending, it can be used. Problems such as peeling are unlikely to occur.

In some preferred embodiments of the techniques disclosed herein (including reinforcing films, optics and electronic members; the same shall apply hereinafter), the pressure-sensitive adhesive layer has a bulk modulus G'23 at ₂₃ ° C. of 10. It is ~ 200 kPa. According to the pressure-sensitive adhesive having a bulk elastic modulus _G'23 in this range, the adhesive strength at the initial stage of application tends to be in a suitable range excellent in light peelability. In addition, it is excellent in workability, and generally tends to have both strain relaxation property and bending recovery property in a normal temperature range.

In some preferred embodiments, the pressure-sensitive adhesive layer has a bulk modulus G'80 at ₈₀ ° C. of 5-100 kPa. A pressure-sensitive adhesive having a bulk elastic modulus _G'80 in this range generally tends to have both bending recovery and bending holding force. For example, even when it is used under a high temperature condition of about 80 ° C., it may have elasticity suitable for bending recovery and have an adhesive holding force for realizing bending holding force.

In some preferred embodiments, the pressure-sensitive adhesive layer has a tan δ ₈₀ of 0.10 to 0.60 at 80 ° C. A pressure-sensitive adhesive having a tan δ ₈₀ (loss elastic modulus G at 80 ° C. G ″ ₈₀ / storage elastic modulus G '80 at ₈₀ ° C.) of 0.10 or more tends to exhibit an adhesive force suitable for bending retention. When the tan δ ₈₀ is 0.60 or less, the plastic deformation of the adhesive is suppressed and good bending recovery is easily obtained. Further, even when the reinforcing film is held in the bent state for a long time, It is easy to exert a holding force (bending holding force) that does not cause peeling from the adherend.

The polymer (A) is preferably an acrylic polymer. According to the pressure-sensitive adhesive layer containing the polymer (A) which is an acrylic polymer and the polymer (B) containing a monomer unit having a polyorganosiloxane skeleton, the effects of the techniques disclosed herein are preferably realized.

In some preferred embodiments, the content of the polymer (B) in the pressure-sensitive adhesive layer is 0.5 to 5 parts by weight with respect to 100 parts by weight of the polymer (A). By setting the amount of the polymer (B) to 0.5 parts by weight or more with respect to 100 parts by weight of the polymer (A), it is easy to obtain light peelability at the initial stage of application. By setting the amount of the polymer (B) to 5 parts by weight or less, it is easy to realize the desired increase in adhesive strength. Further, by setting the amount of the polymer (B) used in the above range, it is easy to realize good bending recovery and bending holding force.

In some preferred embodiments, the molar ratio ([NCO] / [OH]) of the isocyanate group to the hydroxyl group contained in the pressure-sensitive adhesive layer is 0.002 to 0.03. The pressure-sensitive adhesive layer having the molar ratio ([NCO] / [OH]) of 0.002 or more tends to be excellent in bending recovery property and processability. Further, by setting the molar ratio ([NCO] / [OH]) to 0.03 or less, it tends to be easy to realize a suitable increase in adhesive strength. In the pressure-sensitive adhesive layer, the isocyanate group and the hydroxyl group may exist in a state where at least a part thereof is chemically bonded (crosslinked). The pressure-sensitive adhesive layer contains, for example, a cross-linking agent, and in such a configuration, the isocyanate group may be, for example, a part of the cross-linking agent, and the hydroxyl group may be, for example, a part of the polymer (A).

The reinforcing film disclosed here is suitable as a reinforcing film that imparts rigidity and impact resistance to the optical member, for example, during processing or transportation of an optical member such as a polarizing plate or a wave plate. Accordingly, according to the present specification, there is provided an optical member to which any of the reinforcing films disclosed herein is attached.

Further, the reinforcing film disclosed herein is also suitable as a reinforcing film for an electronic member of a device such as a portable electronic device. Therefore, according to the present specification, there is provided an electronic member to which any of the reinforcing films disclosed herein is attached.

It is sectional drawing which shows typically the structure of the reinforcing film which concerns on one Embodiment. It is sectional drawing which shows typically the structure of the reinforcing film which concerns on another embodiment. It is sectional drawing which shows typically the structure of the reinforcing film which concerns on another embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings regarding the implementation of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.
In the following drawings, members / parts having the same function may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are schematically for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actually provided product.

Further, in the present specification, the "acrylic polymer" refers to a polymer containing a monomer unit derived from a (meth) acrylic monomer in a polymer structure, and is typically a monomer derived from a (meth) acrylic monomer. A polymer containing a unit of more than 50% by weight. Further, the (meth) acrylic monomer means a monomer having at least one (meth) acryloyl group in one molecule. Here, the "(meth) acryloyl group" has the meaning of comprehensively referring to an acryloyl group and a methacryloyl group. Therefore, the concept of the (meth) acrylic monomer here may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer). Similarly, in this specification, "(meth) acrylic acid" means acrylic acid and methacrylic acid, and "(meth) acrylate" means acrylate and methacrylate, respectively.

<Structural example of reinforcing film>
The reinforcing film disclosed herein has the form of an adhesive sheet having an adhesive surface formed by an adhesive. The pressure-sensitive adhesive sheet used as a reinforcing film is configured to include a pressure-sensitive adhesive layer. The reinforcing film disclosed herein may be in the form of a pressure-sensitive adhesive sheet with a base material in which the pressure-sensitive adhesive layer is laminated on one side or both sides of a support base material, and is a base material-less pressure-sensitive adhesive sheet having no support base material. It may be in the form of.
In addition, in this specification, a "reinforcing film" means an adhesive sheet (adhesive film for reinforcement) used for reinforcing an adherend as described later. The reinforcing film is, for example, in the form of a base material-less adhesive sheet, in which a support material or the like is attached to one adhesive surface and then the other adhesive surface is attached to an adherend to be reinforced to reinforce the film. Therefore, it is not limited to the form of the pressure-sensitive adhesive sheet with a base material. In this respect, it is understood as a concept in a broader sense than the "reinforcing film" described later, which has the form of an adhesive sheet with a base material.

FIG. 1 schematically shows the structure of the reinforcing film according to one embodiment. The reinforcing film 1 is a single-sided pressure-sensitive adhesive sheet with a base material including a sheet-shaped support base material 10 having a first surface 10A and a second surface 10B, and an adhesive layer 21 provided on the first surface 10A side thereof. It is configured as. The pressure-sensitive adhesive layer 21 is fixed to the first surface 10A side of the support base material 10. The reinforcing film 1 is used by attaching the pressure-sensitive adhesive layer 21 to the adherend. As shown in FIG. 1, the reinforcing film 1 before use (that is, before being attached to the adherend) has the surface (adhesive surface) 21A of the adhesive layer 21 peeled off at least on the side facing the adhesive layer 21. It may be a component of the reinforcing film 100 with a peeling liner in a form of being in contact with the peeling liner 31 which is a property surface (peeling surface). As the peeling liner 31, for example, a sheet-like base material (liner base material) having a peeling layer provided on one side thereof so that one side becomes a peeling surface can be preferably used. Alternatively, the release liner 31 is omitted, the support base material 10 having the second surface 10B as the release surface is used, and the adhesive surface 21A is wound around the reinforcing film 1 so that the adhesive surface 21A is the second surface 10B of the support base material 10. It may be in contact with the (roll form). When the reinforcing film 1 is attached to the adherend, the release liner 31 or the second surface 10B of the support base material 10 is peeled off from the adhesive surface 21A, and the exposed adhesive surface 21A is pressure-bonded to the adherend.

FIG. 2 schematically shows the structure of the reinforcing film according to the other embodiment. The reinforcing film 2 is provided on the sheet-shaped support base material 10 having the first surface 10A and the second surface 10B, the adhesive layer 21 provided on the first surface 10A side thereof, and the second surface 10B side. It is configured as a double-sided pressure-sensitive adhesive sheet with a base material comprising the pressure-sensitive adhesive layer 22. The pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) 21 is fixed to the first surface 10A of the support base material 10, and the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) 22 is fixed to the second surface 10B of the support base material 10. There is. The reinforcing film 2 is used by attaching the pressure-sensitive adhesive layers 21 and 22 to different parts of the adherend. The locations where the pressure-sensitive adhesive layers 21 and 22 are attached may be the respective locations of different members, or may be different locations within a single member. As shown in FIG. 2, in the reinforcing film 2 before use, the surface (first adhesive surface) 21A of the pressure-sensitive adhesive layer 21 and the surface (second adhesive surface) 22A of the pressure-sensitive adhesive layer 22 are at least the pressure-sensitive adhesive layer 21. , 22 may be a component of the reinforcing film 200 with a release liner in a form of being in contact with the release lines 31 and 32 whose sides facing the release lines are the release surfaces, respectively. As the

release liners

31 and 32, for example, those configured by providing a release layer with a release treatment agent on one side of a sheet-shaped base material (liner base material) so that one side becomes a release surface are preferably used. obtain. Alternatively, the release liner 32 is omitted, a release liner 31 having both sides as release surfaces is used, and the release liner 31 is overlapped with the reinforcing film 2 and wound in a spiral shape so that the second adhesive surface 22A becomes a release liner. A reinforcing film with a release liner in a form (roll form) in contact with the back surface of 31 may be configured.

The structure of the reinforcing film according to still another embodiment is schematically shown in FIG. The reinforcing film 3 is configured as a base-less double-sided pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer 21. The reinforcing film 3 has a first adhesive surface 21A composed of one surface (first surface) of the adhesive layer 21 and a second adhesive surface composed of the other surface (second surface) of the adhesive layer 21. It is used by attaching the surface 21B to different parts of the adherend. As shown in FIG. 3, the reinforcing film 3 before use has a release liner 31, in which the first adhesive surface 21A and the second adhesive surface) 21B have peeling surfaces at least on the sides facing the adhesive layer 21. It may be a component of the reinforcing film 300 with a release liner in the form of abutting on 32. Alternatively, the release liner 32 is omitted, a release liner 31 having both sides as release surfaces is used, and the release liner 31 is overlapped with the reinforcing film 3 and wound in a spiral shape so that the second adhesive surface 21B becomes a release liner. A reinforcing film with a release liner in a form (roll form) in contact with the back surface of 31 may be configured.

The reinforcing film may be in a roll form, a single-wafer form, or may be cut or punched into an appropriate shape according to the intended use and usage mode. The pressure-sensitive adhesive layer in the technique disclosed herein is typically formed continuously, but is not limited to this, even if it is formed in a regular or random pattern such as a dot shape or a striped shape. good.

<Adhesive layer>
The reinforcing film disclosed herein comprises a pressure-sensitive adhesive layer comprising the polymer (A) and the polymer (B). Such a pressure-sensitive adhesive layer may be formed from a pressure-sensitive adhesive composition containing the polymer (A), which is a complete polymer or a partial polymer of the monomer raw material A, and the polymer (B). The form of the pressure-sensitive adhesive composition is not particularly limited, and may be various forms such as a solvent type, a water-dispersed type, a hot melt type, and an active energy ray-curable type (for example, a photocurable type).

(23 ° C surface elastic modulus)
The pressure-sensitive adhesive layer disclosed herein is characterized by having a surface elastic modulus (23 ° C. surface elastic modulus) of its surface (adhesive surface) at 23 ° C. in the range of 1 to 20 kPa. When the 23 ° C. surface elastic modulus is 1 kPa or more, it is possible to have good bending recovery while realizing the adhesive property based on the content of the polymer (A) and the polymer (B). Further, when the surface elastic modulus is 20 kPa or less, it is possible to exhibit a good bending holding force while realizing the above-mentioned adhesive characteristics.

From the viewpoint of improving bending recovery, the 23 ° C. surface elastic modulus is preferably 2 kPa or more, more preferably 3 kPa or more, further preferably 4 kPa or more (for example, 5 kPa or more), and may be 8 kPa or more, and may be 10 kPa or more. However, it may be 12 kPa or more (for example, 14 kPa or more). The higher the surface elastic modulus, the better the initial light peelability tends to be. Further, from the viewpoint of preferably exhibiting an increase in adhesive strength while achieving both good bending recovery and bending holding power, the 23 ° C. surface elastic modulus is preferably 15 kPa or less, preferably 12 kPa or less, and more preferably 9 kPa. Hereinafter, it is more preferably 7 kPa or less (for example, 6 kPa or less), and may be 4 kPa or less.

The 23 ° C surface elasticity of the pressure-sensitive adhesive layer is determined by the type and characteristics (molecular weight, glass transition temperature, molecular structure, etc.) of the polymer (A), and the type (chemical structure, etc.) and characteristics (molecular weight, glass transition temperature, etc.) of the polymer (B). Etc.), the amount used, the type of cross-linking agent, the amount used, etc. can be adjusted. The 23 ° C. surface elastic modulus of the pressure-sensitive adhesive layer is measured by the method described in Examples described later.

( ₂₃ ° C bulk elastic modulus G'23)
The bulk elastic modulus G'23 ( ₂₃ ° C. bulk elastic modulus _G'23 ) of the pressure-sensitive adhesive layer at 23 ° C. is appropriately set within a range satisfying the above range of the 23 ° C. surface elastic modulus and is limited to a specific range. It is not something that will be done. In some embodiments, it is appropriate that the ₂₃ ° C. bulk elastic modulus G'23 of the pressure-sensitive adhesive layer is 10 kPa or more. By setting the bulk elastic modulus _G'23 to a predetermined value or more, the adhesive force at the initial stage of application tends to be in a suitable range excellent in light peelability. In addition, it is excellent in workability and generally tends to be excellent in bending recovery in the normal temperature range. The bulk elastic modulus _G'23 is preferably 15 kPa or more, more preferably 20 kPa or more, still more preferably 25 kPa or more, and particularly preferably 30 kPa or more. In some other embodiments, the bulk modulus _G'23 may be 50 kPa or higher, 80 kPa or higher, or 100 kPa or higher.

In some embodiments, it is appropriate that the ₂₃ ° C. bulk elastic modulus G'23 of the pressure-sensitive adhesive layer is 200 kPa or less. The pressure-sensitive adhesive having a bulk elastic modulus _G'23 of less than or equal to a predetermined value generally tends to have excellent strain-relieving properties in the normal temperature range, and tends to exhibit an increase in adhesive strength. The bulk elastic modulus _G'23 is preferably 150 kPa or less, more preferably 90 kPa or less. In some preferred embodiments, the bulk modulus _G'23 may be 60 kPa or less, or 40 kPa or less (eg, 35 kPa or less).

(80 ° C bulk elastic modulus _G'80 )
The bulk elastic modulus G'80 ( ₈₀ ° C. bulk elastic modulus _G'80 ) of the pressure-sensitive adhesive layer at 80 ° C. is appropriately set within a range satisfying the above range of the 23 ° C. surface elastic modulus and is limited to a specific range. It is not something that will be done. In some embodiments, the ₈₀ ° C. bulk elastic modulus G'80 of the pressure-sensitive adhesive layer is preferably 5 kPa or higher. By setting the bulk elastic modulus _G'80 to a predetermined value or more, the bending recovery property is generally easy to improve, and even when used under high temperature conditions, the elastic modulus suitable for bending recovery can be obtained. In some preferred embodiments, the bulk modulus _G'80 may be 7 kPa or higher, 9 kPa or higher, or 10 kPa or higher. In some other embodiments, the bulk modulus _G'80 may be 15 kPa or higher, 30 kPa or higher, or 50 kPa or higher.

In some embodiments, it is appropriate that the ₈₀ ° C. bulk elastic modulus G'80 of the pressure-sensitive adhesive layer is 100 kPa or less. By limiting the bulk elastic modulus _G'80 to a predetermined value or less, it is generally easy to obtain a good bending holding force, and it is easy to achieve both bending recovery and bending holding force. For example, in various environments including high temperature conditions, it may have elasticity suitable for bending recovery and have adhesive holding force to realize bending holding force. The bulk elastic modulus _G'80 is preferably 90 kPa or less, more preferably 60 kPa or less. In some embodiments, the bulk modulus _G'80 may be 20 kPa or less, 16 kPa or less, or 14 kPa or less (eg, 12 kPa or less).

(80 ° C tanδ ₈₀ )
The tanδ ₈₀ (80 ° C. tanδ ₈₀ ) of the pressure-sensitive adhesive layer at 80 ° C. is appropriately set within a range satisfying the above range of the 23 ° C. surface elastic modulus, and is not limited to a specific range. In some embodiments, it is appropriate that the 80 ° C. tan δ ₈₀ of the pressure-sensitive adhesive layer is 0.10 or higher. The higher the tan δ ₈₀ , the easier it is for the pressure-sensitive adhesive to exhibit an adhesive force suitable for bending and holding. The tan δ ₈₀ is preferably 0.20 or more. In some preferred embodiments, the tan δ ₈₀ may be 0.30 or higher, 0.40 or higher, or 0.45 or higher.

In some embodiments, the 80 ° C. tan δ ₈₀ of the pressure-sensitive adhesive layer is preferably 0.60 or less. When the tan δ ₈₀ is 0.60 or less, the plastic deformation of the pressure-sensitive adhesive is suppressed, and good bending recovery is easily obtained. Further, even when the reinforcing film is held in a bent state for a long time, it is easy to exert a holding force that does not cause peeling from the adherend. Further, the increase in adhesive strength tends to be in a suitable range. The 80 ° C. tan δ ₈₀ may be 0.55 or less. In some other embodiments, the 80 ° C. tan δ ₈₀ may be 0.50 or less, or 0.35 or less.

The ₂₃ ° C. bulk elastic modulus G'23, 80 ° C. bulk elastic modulus G'80 and ₈₀ ° C. tanδ ₈₀ of the pressure-sensitive adhesive layer are the types and characteristics of the polymer (A) (molecular weight, glass transition temperature, molecular structure, etc.) and the polymer (molecular weight, glass transition temperature, molecular structure, etc.). It can be adjusted according to the type (chemical structure, etc.) and characteristics (molecular weight, glass transition temperature, etc.) of B), the amount used, the type of the cross-linking agent, the amount used, and the like. The ₂₃ ° C. bulk elastic modulus G'23, the 80 ° C. bulk elastic modulus G'80 and the ₈₀ ° C. tanδ ₈₀ of the pressure-sensitive adhesive layer are measured by the methods described in Examples described later.

(Polymer (A))
Examples of the polymer (A) include acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers known in the field of pressure-sensitive adhesives at room temperature. One or more of various polymers showing rubber elasticity in the region can be used. In the reinforcing film disclosed herein, the polymer (A) is typically the main component of the polymer component contained in the pressure-sensitive adhesive layer, that is, a component occupying more than 50% by weight, for example, 75 of the above polymer components. It can be a component that accounts for more than% by weight. In some embodiments, the polymer (A) is a component that occupies more than 50% by weight of the entire pressure-sensitive adhesive layer, may be a component that occupies 70% by weight or more, or may be a component that occupies 80% by weight or more. , 90% by weight or more, or 95% by weight or more (for example, 97% by weight or more) may be used.

The glass transition temperature TA of the polymer ( _A ) is not particularly limited and can be selected so as to obtain preferable properties in the reinforcing film disclosed herein. In some embodiments, the polymer ( _A ) having a TA of less than 0 ° C. may be preferably employed. Since the pressure-sensitive adhesive containing the polymer (A) exhibits appropriate fluidity (for example, the motility of the polymer chains contained in the pressure-sensitive adhesive), it is used for reinforcement in which the pressure-sensitive adhesive strength increases to a predetermined value or more by heating. Suitable for realization of film. The reinforcing film disclosed herein can be preferably carried out using a polymer ( _A ) having a TA of less than −10 ° C., less than −20 ° C., less than −30 ° C. or less than −35 ° C. In some embodiments, _TA may be below −40 ° C. or below −50 ° C. In some preferred embodiments, the _TA is −55 ° C. or lower, more preferably −58 ° C. or lower, even more preferably −62 ° C. or lower, and may be −65 ° C. or lower (eg, −66 ° C. or lower). The lower limit of _TA is not particularly limited. From the viewpoint of easy availability of the material and improvement of the cohesive force of the pressure-sensitive adhesive layer, a polymer ( _A ) having a TA of −80 ° C. or higher and −70 ° C. or higher can be preferably adopted. In some embodiments, _TA may be, for example, −63 ° C. or higher, −55 ° C. or higher, −50 ° C. or higher, or −45 ° C. or higher.

Here, in this specification, is the glass transition temperature (Tg) of the polymer (for example, the glass transition temperature of the polymer (A), the polymer (B) described later, etc.) a nominal value described in documents, catalogs, and the like? , Or Tg determined by the Fox formula based on the composition of the monomer raw material used in the preparation of the polymer. As shown below, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1 / Tg = Σ (Wi / Tgi)
In the Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the homopolymer of the monomer i. Represents the glass transition temperature (unit: K) of. When the target polymer for specifying Tg is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer are the same.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. Specifically, the figures are listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). For the monomers for which multiple types of values are described in the above Polymer Handbook, the highest value is adopted.

As the glass transition temperature of the homopolymer of the monomer not described in the above Polymer Handbook, the value obtained by the following measuring method shall be used.
Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by weight of a monomer, 0.2 parts by weight of 2,2'-azobisisobutyronitrile and acetic acid as a polymerization solvent. Add 200 parts by weight of ethyl and stir for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample is punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and shear strain with a frequency of 1 Hz using a viscoelasticity tester (manufactured by TA Instruments Japan, model name "ARES"). The viscoelasticity is measured in a shear mode at a temperature range of −70 ° C. to 150 ° C. and a temperature rise rate of 5 ° C./min, and the temperature corresponding to the peak top temperature of tan δ is defined as Tg of the homopolymer.

Although not particularly limited, it is generally appropriate that the weight average molecular weight (Mw) of the polymer (A) is about 20 × ¹⁰⁴ or more. According to the polymer (A) of Mw, it is easy to obtain a pressure-sensitive adhesive showing good cohesiveness. From the viewpoint of obtaining higher cohesive force, in some preferred embodiments, the Mw of the polymer (A) may be, for example, 30 × 10 ⁴ or more, 40 × 10 ⁴ or more, or 50 × 10 ⁴ or more. , 60 × 10 ⁴ or more, or 80 × 10 ⁴ or more. Further, it is usually appropriate that the Mw of the polymer (A) is about 500 × ¹⁰⁴ or less. Since the polymer (A) of Mw easily forms a pressure-sensitive adhesive exhibiting appropriate fluidity (movement of polymer chains), a reinforcing film having a low adhesive strength at the initial stage of application and a large increase in adhesive strength can be realized. Suitable for. It is preferable that the Mw of the polymer (A) is not too high from the viewpoint of improving the compatibility with the polymer (B). In some preferred embodiments, the Mw of the polymer (A) may be, for example, 250 × 10 ⁴ or less, 200 × 10 ⁴ or less, 150 × 10 ⁴ or less, 100 × 10 ⁴ or less. It may be 70 × 10 ⁴ or less.

In this specification, the Mw of the polymer (A) and the polymer (B) described later can be determined by polystyrene conversion by gel permeation chromatography (GPC). More specifically, Mw can be measured according to the methods and conditions described in the examples described later.

As the polymer (A) in the reinforcing film disclosed here, an acrylic polymer can be preferably adopted. When an acrylic polymer is used as the polymer (A), good compatibility with the polymer (B) tends to be easily obtained. The good compatibility between the polymer (A) and the polymer (B) can contribute to the reduction of the initial adhesive force and the improvement of the adhesive force after heating by improving the mobility of the polymer (B) in the pressure-sensitive adhesive layer. preferable. Further, an acrylic polymer having a high degree of freedom in molecular design is suitable as a pressure-sensitive adhesive material capable of improving adhesive properties, bending recovery and bending holding power in a well-balanced manner.

The acrylic polymer is, for example, a polymer containing 50% by weight or more of a monomer unit derived from (meth) acrylic acid alkyl ester, that is, 50 out of the total amount of the monomer component (monomer raw material A) for preparing the acrylic polymer. It can be a polymer in which% by weight or more is a (meth) acrylic acid alkyl ester. As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms (that is, C _1-20 ) can be preferably used. Since it is easy to balance the characteristics, the ratio of the (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 50% by weight or more, or 60% by weight or more. In some preferred embodiments, the proportion of (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A is 70% by weight or more, more preferably 80% by weight or more, still more preferably 85% by weight or more. Particularly preferably, it is 90% by weight or more. By using an acrylic polymer having such a monomer composition, it is easy to obtain a pressure-sensitive adhesive having both an increase in adhesive strength and a bending recovery property and a bending holding force in a well-balanced manner. The proportion of the (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. In some embodiments, the proportion of the (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

Non-limiting specific examples of the (meth) acrylic acid C _1-20 alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, and isopropyl (meth) acrylic acid. N-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Hexyl acrylate, (meth) heptyl acrylate, (meth) octyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) ) Decyl acrylate, (meth) isodecyl acrylate, (meth) undecyl acrylate, (meth) dodecyl acrylate, (meth) tridecyl acrylate, (meth) tetradecyl acrylate, (meth) pentadecyl acrylate, (meth) Examples thereof include hexadecyl acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate.

Of these, it is preferable to use at least (meth) acrylic acid C _1-18 alkyl ester, and it is more preferable to use at least (meth) acrylic acid C _1-14 alkyl ester. In some embodiments, the acrylic polymer is at least one selected from (meth) acrylic acid C _4-12 alkyl esters (preferably acrylic acid C _4-10 alkyl esters, eg acrylic acid C _6-10 alkyl esters). Can be contained as a monomer unit. For example, an acrylic polymer containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) is preferable, and an acrylic polymer containing at least 2EHA is particularly preferable.

In some preferred embodiments, the proportion of acrylic acid C _6-10 alkyl ester (preferably acrylic acid C _8-9 alkyl ester, typically 2EHA) in the monomer raw material A for preparing the acrylic polymer is , 70% by weight or more, more preferably 80% by weight or more, still more preferably 85% by weight or more, and particularly preferably 90% by weight or more. Acrylic polymers with such a monomer composition are particularly suitable for achieving the effects of the techniques disclosed herein. The proportion of acrylic acid C _6-10 alkyl ester (preferably acrylic acid C _8-9 alkyl ester, typically 2EHA) in the monomer raw material A may be, for example, 99.9% by weight or less. From the viewpoint of initial low adhesive strength, bending recovery, etc., it may be 98% by weight or less, or 95% by weight or less.

Also, in some preferred embodiments, the (meth) acrylic acid C _1-3 alkyl ester (eg, (meth) acrylic acid C ₁ alkyl ester, typically methacrylic) in the monomer raw material A for preparing the acrylic polymer. It is preferable that the proportion of methyl acid (MMA)) is limited. (Meta) acrylic acid C _1-3 alkyl ester (for example, (meth) acrylic acid C ₁ alkyl ester, typically MMA) tends to have a relatively high Tg, and is an acrylic polymer using the above-mentioned monomer component. Adhesives containing, tend to be highly cohesive. By limiting the amount of (meth) acrylic acid C _1-3 alkyl ester used, the cohesive force of the adhesive is appropriately reduced, and the elastic modulus suitable for achieving both bending holding force and increasing adhesive force (typically). Is a surface elastic modulus) can be preferably realized. From such a viewpoint, the ratio of (meth) acrylic acid C _1-3 alkyl ester (for example, (meth) acrylic acid C ₁ alkyl ester, typically MMA) to the above-mentioned monomer raw material A is 8% by weight or less. It is suitable, preferably 6% by weight or less, more preferably 3% by weight or less, still more preferably 1% by weight or less (for example, 0 to 0.3% by weight).

The monomer raw material A may contain a (meth) acrylic acid alkyl ester as a main component and, if necessary, another monomer (copolymerizable monomer) copolymerizable with the (meth) acrylic acid alkyl ester. .. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. Monomers having polar groups can be useful for introducing cross-linking points in acrylic polymers and for enhancing the cohesive power of acrylic polymers. The copolymerizable monomer may be used alone or in combination of two or more.

Non-limiting specific examples of the copolymerizable monomer include the following.
Hydroxyl-containing monomers: For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic. 4-Hydroxybutyl acid, 6-hydroxyhexyl (meth) acrylic acid, 8-hydroxyoctyl (meth) acrylic acid, 10-hydroxydecyl (meth) acrylic acid, 12-hydroxylauryl (meth) acrylic acid, (4-hydroxy) Methylcyclohexyl) Methyl (meth) acrylate and the like (meth) hydroxyalkyl acrylate and the like.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloyl pyrrolidine, N- (meth) acryloyl morpholine, N- Vinylmorpholin, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N -Vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc .;
Monomers having a succinimide skeleton, such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide;
Maleimides such as, for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; and
For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. Itaconimides.
Monomer containing carboxy group: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomer: For example, maleic anhydride, itaconic anhydride.
Epoxide group-containing monomer: For example, epoxy group-containing acrylate such as (meth) glycidyl acrylate and (meth) -2-ethyl glycidyl ether, allyl glycidyl ether, glycidyl ether (meth) acrylate and the like.
Cyano group-containing monomer: For example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomer: For example, 2-isocyanatoethyl (meth) acrylate and the like.
Amide group-containing monomers: For example, (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth). N, N-dialkyl (meth) acrylamide, such as acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide; N-ethyl (meth) N-alkyl (meth) acrylamide such as acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide; N-vinylcarboxylic acid amide such as N-vinylacetamide. Classes; monomers having a hydroxyl group and an amide group, such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth). Acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) ( N-hydroxyalkyl (meth) acrylamide, such as meta) acrylamide; monomers with an alkoxy group and an amide group, such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl ( N-alkoxyalkyl (meth) acrylamide such as meta) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide and the like.
Aminoalkyl (meth) acrylates: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t (meth) acrylate. -Butyl aminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth) acrylic acid. Alkoxyalkyls (meth) acrylates such as butoxyethyl, ethoxypropyl (meth) acrylates; alkoxyalkylene glycols (meth) acrylates such as methoxyethylene glycol (meth) acrylates, methoxypolypropylene glycols (meth) acrylates, etc. Kind.
Monomer containing a sulfonic acid group or a phosphate group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfo. Propyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.
(Meta) acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate and the like.
(Meta) acrylic acid ester having an aromatic hydrocarbon group: For example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate and the like.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Vinyl esters: For example, vinyl acetate, vinyl propionate, etc.
Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
In addition, heterocyclic-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride and fluorine atom-containing (meth) acrylates, and silicon atom-containing silicone (meth) acrylates. (Meta) acrylate, (meth) acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use 0.01% by weight or more of the monomer raw material A. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more of the monomer raw material A or 1% by weight or more. In some preferred embodiments, the content of the copolymerizable monomer in the monomer raw material A is 3% by weight or more, more preferably 5% by weight or more, still more preferably 7% by weight or more (for example, 8% by weight or more). Is. As the amount of the copolymerizable monomer used increases, the cohesiveness tends to increase and the bending recovery property tends to improve. Further, the amount of the copolymerizable monomer used can be 50% by weight or less of the monomer raw material A, and is preferably 30% by weight or less. This prevents the cohesive force of the adhesive from becoming too high, and can improve the tackiness at room temperature (25 ° C.). In some preferred embodiments, the amount of the copolymerizable monomer used is 20% by weight or less, more preferably 15% by weight or less (eg, 12% by weight or less), and 10% by weight or less of the monomer raw material A. You may. By limiting the amount of the copolymerizable monomer used, the cohesive force of the adhesive is reduced, the elastic modulus (typically the surface elastic modulus) is in a suitable range, and excellent bending holding force is easily obtained, and the adhesive is adhered. It is easy to realize an increase in power.

In some embodiments, the monomer raw material A may contain a monomer having a nitrogen atom-containing ring. By using a monomer having a nitrogen atom-containing ring, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after heating can be suitably improved. By including the monomer having a nitrogen atom-containing ring in the monomer raw material A, the compatibility between the polymer (A) formed from the monomer raw material A and the polymer (B) tends to be improved. This makes it easier to obtain a reinforcing film that can greatly increase the adhesive strength by heating.

The monomer having a nitrogen atom-containing ring can be appropriately selected from the above examples, and can be used alone or in combination of two or more. In some embodiments, the monomer raw material A contains, as the monomer having a nitrogen atom-containing ring, at least one monomer selected from the group consisting of an N-vinyl cyclic amide and a cyclic amide having a (meth) acryloyl group. Is preferable.

Specific examples of the N-vinyl cyclic amide include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, and N-vinyl-1,3. -Oxazine-2-one, N-vinyl-3,5-morpholindione and the like can be mentioned. Particularly preferred are N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.
Specific examples of the cyclic amide having a (meth) acryloyl group include N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidin, N- (meth) acryloylpyrrolidine, N- (meth) acryloylmorpholine and the like. Can be mentioned. Preferable examples include N-acryloyl morpholine (ACMO).

The amount of the monomer having a nitrogen atom-containing ring is not particularly limited, and is usually appropriately 40% by weight or less of the monomer raw material A, 30% by weight or less, or 20% by weight or less. It may be 10% by weight or less. In some preferred embodiments, the content of the monomer having a nitrogen atom-containing ring in the monomer raw material A is 7% by weight or less from the viewpoint of lowering the cohesive force and lowering the elastic modulus (typically, the surface elastic modulus). It is more preferably 5% by weight or less, still more preferably 3% by weight or less (for example, 1.5% by weight or less). Further, it is usually appropriate that the amount of the monomer having a nitrogen atom-containing ring used is 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer raw material A. be. From the viewpoint of obtaining an appropriate cohesive force and elastic modulus, in some embodiments, the amount of the monomer having a nitrogen atom-containing ring may be 0.8% by weight or more of the monomer raw material A, 1.0% by weight or more. May be.

In some preferred embodiments, the monomer raw material A comprises a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force and polarity of the pressure-sensitive adhesive, and thus the elastic modulus (typically, the surface elastic modulus) can be adjusted, and the effect of the technique disclosed herein can be preferably realized. Further, the hydroxyl group-containing monomer provides a reaction point with a cross-linking agent (for example, an isocyanate-based cross-linking agent) described later, and the cohesive force of the pressure-sensitive adhesive can be enhanced by the cross-linking reaction.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and N- (2-hydroxyethyl) (meth) acrylamide. It can be suitably used. Among them, preferred examples include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4HBA), and N- (2-hydroxyethyl) acrylamide (HEAA). 4HBA is particularly preferable from the viewpoint of obtaining a cohesive force suitable for bending recovery and bending holding force.

The amount of the hydroxyl group-containing monomer used is not particularly limited, and is usually appropriately 40% by weight or less of the monomer raw material A, 30% by weight or less, or 20% by weight or less. In some preferred embodiments, the content of the hydroxyl group-containing monomer in the monomer raw material A is 15% by weight or less, more preferably, from the viewpoint of reducing the cohesive force and thus the elastic modulus (typically, the surface elastic modulus). Is 12% by weight or less (for example, 10% by weight or less). By limiting the amount of the hydroxyl group-containing monomer used, the mobility of the polymer (B) in the pressure-sensitive adhesive layer is improved, and it is easy to realize an increase in the pressure-sensitive adhesive force. In some other embodiments, the content of the hydroxyl group-containing monomer may be 5% by weight or less of the monomer raw material A. Further, it is appropriate that the amount of the hydroxyl group-containing monomer used is 0.01% by weight or more (preferably 0.1% by weight or more, for example, 0.5% by weight or more) of the monomer raw material A. From the viewpoint of obtaining an appropriate cohesive force and elastic modulus, in some preferred embodiments, the amount of the hydroxyl group-containing monomer used is 1% by weight or more, more preferably 3% by weight or more, still more preferably 5 of the monomer raw material A. It is 7% by weight or more, particularly preferably 7% by weight or more (for example, 8% by weight or more).

In some embodiments, a monomer having a nitrogen atom-containing ring and a hydroxyl group-containing monomer can be used in combination as the copolymerizable monomer. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer can be, for example, 0.1% by weight or more of the monomer raw material A, preferably 1% by weight or more, and more preferably 3% by weight. % Or more, more preferably 5% by weight or more, particularly preferably 7% by weight or more (for example, 9% by weight or more), 10% by weight or more, 15% by weight or more, or 20% by weight or more. It may be 25% by weight or more. Further, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer can be, for example, 50% by weight or less of the monomer raw material A, and is preferably 30% by weight or less. In some preferred embodiments, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer is 20% by weight or less, more preferably 15% by weight or less (for example, 12% by weight or less) of the monomer raw material A. be.

In an embodiment in which the monomer raw material A contains a monomer having a nitrogen atom-containing ring and a hydroxyl group-containing monomer in combination, the content (WN) of the monomer having a _nitrogen atom-containing ring and the content of the hydroxyl group-containing monomer in the monomer raw material A (WN). The relationship (weight basis) with _WOH ) is not particularly limited. W _N / W _OH may be, for example, 0.01 or more, usually 0.05 or more, 0.10 or more, or 0.12 or more. Further, W _N / W _OH may be, for example, 10 or less, usually 1 or less is appropriate, preferably 0.50 or less, 0.30 or less, 0.20 or less, and 0. It may be .15 or less.

In some embodiments, the monomer raw material A does not contain a monomer having a polyorganosiloxane skeleton (monomer S1) which is preferably used as a constituent component of the monomer raw material B described later, or the content of the monomer is the monomer raw material A. It is preferably less than 10% by weight (more preferably less than 5% by weight, for example, less than 2% by weight). According to the monomer raw material A having such a composition, a reinforcing film having a good balance between initial reworkability and strong adhesiveness after an increase in adhesive strength can be preferably realized. For the same reason, in some other embodiments, the monomer raw material A does not contain the monomer S1 or, if it contains the monomer S1, its content (weight basis) is higher than the content of the monomer S1 in the monomer raw material B. Low is preferable.

The method for obtaining the polymer (A) is not particularly limited, and various polymerization methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method can be appropriately adopted. In some embodiments, the solution polymerization method may be preferably employed. The polymerization temperature at the time of solution polymerization can be appropriately selected depending on the type of the monomer and solvent used, the type of the polymerization initiator and the like, and is, for example, about 20 ° C. to 170 ° C. (typically 40 ° C. to 140 ° C.). ℃).

The initiator used for the polymerization can be appropriately selected from conventionally known thermal polymerization initiators, photopolymerization initiators and the like, depending on the polymerization method. The polymerization initiator may be used alone or in combination of two or more.

Examples of the thermal polymerization initiator include azo-based polymerization initiators (for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis (for example). 2-Methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovalerian acid, azobisisobutyvaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2 -(5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethylene) Isobutylamidin) dihydrochloride, etc.); Persulfate such as potassium persulfate; Peroxide-based polymerization initiator (for example, dibenzoylperoxide, t-butylpermalate, lauroyl peroxide, etc.); Redox-based polymerization initiator, etc. Can be mentioned. The amount of the thermal polymerization initiator used is not particularly limited, but is, for example, 0.01 to 5 parts by weight, preferably 0.01 parts by weight, preferably 5 parts by weight, based on 100 parts by weight of the monomer component (monomer raw material A) used for preparing the polymer (A). The amount can be in the range of 0.05 parts by weight to 3 parts by weight.

The photopolymerization initiator is not particularly limited, and is, for example, a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, and photoactivity. Oxym-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, Ketal-based photopolymerization initiator, thioxanthone-based photopolymerization initiator, acylphosphine oxide-based photopolymerization initiator Agents and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, but is, for example, an amount in the range of 0.01 parts by weight to 5 parts by weight, preferably 0.05 parts by weight to 3 parts by weight with respect to 100 parts by weight of the monomer raw material A. Can be.

In some embodiments, the polymer (A) is a partial polymer obtained by irradiating a mixture of the above-mentioned monomer raw material A with a polymerization initiator with ultraviolet rays (UV) to polymerize a part of the monomer component (a partial polymer). In the form of a polymer syrup), it may be included in a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer. A pressure-sensitive adhesive composition containing such a polymer syrup can be applied to a predetermined object to be coated and irradiated with ultraviolet rays to complete the polymerization. That is, the polymer syrup can be grasped as a precursor of the polymer (A). The pressure-sensitive adhesive layer disclosed herein can be formed, for example, by using a pressure-sensitive adhesive composition containing the polymer syrup and the polymer (B).

(Polymer (B))
The polymer (B) in the technique disclosed herein is the polymerization of a monomer component (monomer raw material B) containing a monomer having a polyorganosiloxane skeleton (hereinafter, also referred to as “monomer S1”) and a (meth) acrylic monomer. It is a thing. The polymer (B) can be said to be a copolymer of the monomer S1 and the (meth) acrylic monomer. The polymer (B) can be used alone or in combination of two or more. The polymer (B) suppresses the adhesive force at the initial stage of attachment to the adherend due to the low polarity and motility of the polyorganosiloxane structure derived from the monomer S1, and increases the adhesive force to the adherend by heating. It can function as an adhesive force increase retarder. The monomer S1 is not particularly limited, and any monomer containing a polyorganosiloxane skeleton can be used. Due to the low polarity derived from the structure of the monomer S1, the polymer (B) is unevenly distributed on the surface of the pressure-sensitive adhesive layer in the reinforcing film before use (before being attached to the adherend), and the initial bonding period. (Low adhesiveness) is exhibited. As the monomer S1, a monomer having a structure having a polymerizable reactive group at one end can be preferably used. According to the configuration including such a monomer S1 unit and a (meth) acrylic monomer unit, a polymer (B) having a polyorganosiloxane skeleton in the side chain is formed. The polymer (B) having such a structure tends to have a low initial adhesive force and a high adhesive force after heating due to the motility and mobility of the side chains. Further, in some embodiments, the monomer S1 preferably has a polymerizable reactive group at one end and does not have a functional group that causes a cross-linking reaction with the polymer (A) at the other end. The polymer (B) in which the monomer S1 having such a structure is copolymerized tends to have a low initial adhesive force and a high adhesive force after heating due to the motility of the polyorganosiloxane structure derived from the monomer S1.

As the monomer S1, for example, a compound represented by the following general formula (1) or (2) can be used. More specifically, examples of the one-ended reactive silicone oil manufactured by Shin-Etsu Chemical Co., Ltd. include X-22-174ASX, X-22-2426, X-22-2475, and KF-22. Monomer S1 can be used alone or in combination of two or more.

Here, R ³ in the above general formulas (1) and (2) is hydrogen or methyl, R ⁴ is a methyl group or a monovalent organic group, and m and n are integers of 0 or more.

The functional group equivalent of the monomer S1 can be an appropriate value within a range in which the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing the initial adhesive force, the functional group equivalent is, for example, 100 g / mol or more, 200 g / mol or more, and 300 g / mol or more (for example, 500 g / mol or more). It is preferably 800 g / mol or more, and more preferably 1500 g / mol or more. In a particularly preferable embodiment, the functional group equivalent is 2000 g / mol or more, more preferably 2500 g / mol or more, and 3000 g, from the viewpoint of achieving both low adhesiveness at the initial stage of application and increase in adhesive strength after heating. It may be / mol or more, 4000 g / mol or more, or 5000 g / mol or more. In some other embodiments, the functional group equivalent may be 9000 g / mol or more, 12000 g / mol or more, or 15000 g / mol or more. In terms of the functional group equivalent of the monomer S1, the functional group means a polymerizable functional group (for example, an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group or an allylic group).

From the viewpoint of sufficiently increasing the adhesive strength, the functional group equivalent is preferably, for example, 30,000 g / mol or less, may be 20,000 g / mol or less, may be less than 15,000 g / mol, and may be less than 10,000 g / mol. But it may be. In some preferred embodiments, the functional group equivalent of the monomer S1 is 7000 g / mol or less, more preferably 5500 g / mol or less, still more preferably 4500 g / mol or less, and may be 4200 g / mol or less, 3500 g / mol or less. It may be as follows. When the functional group equivalent of the monomer S1 is within the above range, the compatibility in the pressure-sensitive adhesive layer (for example, compatibility with the base polymer) tends to be good, and the polyorganosiloxane skeleton (chain) of the polymer (B) tends to be good. It has good motility, and it is easy to adjust the mobility of the polymer (B) to an appropriate range, and it is easy to realize a pressure-sensitive adhesive layer that achieves both initial low adhesiveness and an increase in adhesive strength after heating.

Here, the "functional group equivalent" means the weight of the main skeleton (for example, polydimethylsiloxane) bonded to each functional group. The title unit g / mol is converted to 1 mol of functional group. The functional group equivalent of the monomer S1 can be calculated, for example, from the spectral intensity of ¹ H-NMR (proton NMR) based on nuclear magnetic resonance (NMR). ¹ The calculation of the functional group equivalent (g / mol) of the monomer S1 based on the spectral intensity of 1 H-NMR is based on the general structural analysis method related to ^{1 1} H-NMR spectral analysis, and if necessary, the Japanese Patent No. 1 This can be done with reference to the description in JP-A-591153.

When two or more kinds of monomers having different functional group equivalents are used as the monomer S1, an arithmetic mean value can be used as the functional group equivalent of the monomer S1. That is, the functional group equivalent of the monomer S1 composed of n kinds of monomers having different functional group equivalents (monomer S1 ₁ , monomer S1 ₂ ... Monomer S1 _n ) can be calculated by the following formula.
Functional group equivalent of monomer S1 (g / mol) = (functional equivalent of monomer S1 ₁ × compounding amount of monomer S1 ₁ + functional group equivalent of monomer S1 ₂ × compounding amount of monomer S1 ₂ + ... + monomer S1 _n Functional group equivalent amount × amount of monomer S1 _n ) / (amount of monomer S1 ₁ + amount of monomer S1 ₂ + ... + amount of monomer S1 _n )

The content of the monomer S1 can be an appropriate value within a range in which the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing the initial adhesive force, in some embodiments, the content of the monomer S1 is, for example, 5% by weight or more among the total amount of the monomer component (monomer raw material B) for preparing the polymer (B). It is preferable that the content is 10% by weight or more, more preferably 12% by weight or more, still more preferably 15% by weight or more, and particularly preferably 18% by weight, from the viewpoint of better exerting the effect as an adhesive force increase retarder. It is 20% by weight or more, and may be 20% by weight or more. Further, the content of the monomer S1 in the monomer raw material B may be, for example, 80% by weight or less, preferably 60% by weight or less, preferably 50% by weight, from the viewpoint of polymerization reactivity and compatibility. Hereinafter, it may be more preferably 40% by weight or less, still more preferably 30% by weight or less. By setting the polymerization ratio of the monomer S1 to an appropriate range, an increase in adhesive strength can be suitably exhibited.

The monomer raw material B contains a (meth) acrylic monomer copolymerizable with the monomer S1 in addition to the monomer S1. By using one or more (meth) acrylic monomers, the mobility of the polymer (B) in the pressure-sensitive adhesive layer can be suitably adjusted. It can also help improve the compatibility between the polymer (B) and the polymer (A). Since the polymer (B) containing the (meth) acrylic monomer unit can be well compatible with the acrylic polymer, the initial adhesive strength is reduced and after heating through the improvement of the mobility of the polymer (B) in the pressure-sensitive adhesive layer. It is easy to improve the adhesive strength.

In the polymer (B) used in the technique disclosed herein, the composition of the (meth) acrylic monomer contained in the monomer raw material B is such that the glass transition temperature TB of the polymer ( _B ) is −20 ° C. to 5 ° C. It can be set appropriately in the range. The glass transition temperature _TB1 based on the composition of the (meth) acrylic monomer is also appropriately set within a range satisfying the above _TB , and is not limited to a specific range. Typically, TB1 is preferably set to be higher than the glass transition temperature _TA of the polymer ( _A ). _TB1 can be set to be higher than 0 ° C., for example. Here, the glass transition temperature TB1 based on the composition of the (meth) acrylic monomer is a Fox formula based on the composition of only the (meth) acrylic monomer among the monomer components used for the preparation of the polymer ( _B ). It means Tg obtained by. For TB1, the Fox formula described above is applied only to the (meth) acrylic monomer among the monomer components used in the preparation of the polymer ( _B ), and the glass transition of the homopolymer of each (meth) acrylic monomer is applied. It can be calculated from the temperature and the weight fraction of each (meth) acrylic monomer in the total amount of the (meth) acrylic monomer. According to the polymer ( _B ) having a relatively high glass transition temperature TB1 (typically higher than 0 ° C.), the initial adhesive force is likely to be suppressed. Further, according to the polymer ( _B ) having a relatively high glass transition temperature TB1 (typically higher than 0 ° C.), it is easy to obtain a reinforcing film having a large adhesive force increase ratio.

In some preferred embodiments, _TB1 is 10 ° C. or higher, more preferably 30 ° C. or higher, still more preferably 40 ° C. or higher, and may be 45 ° C. or higher. As _TB1 increases, the adhesive strength at the initial stage of application generally tends to be better suppressed. This is because, according to the polymer ( _B ) in which TB1 is above a predetermined temperature, the improvement of the mobility and mobility of the polyorganosiloxane structural portion with the temperature rise to room temperature or a temperature region higher than room temperature is improved. It is considered that it is effectively suppressed by the monomer unit derived from the (meth) acrylic monomer contained in B), and the low adhesiveness due to the presence of the polyorganosiloxane structural portion can be better maintained. From the viewpoint of maintaining low adhesiveness at the initial stage of application more stably, in some embodiments, _TB1 may be, for example, 50 ° C. or higher, 55 ° C. or higher, or 60 ° C. or higher. Further, _TB1 may be, for example, 120 ° C. or lower, or 100 ° C. or lower. When _TB1 becomes low, the increase in adhesive strength due to heating tends to be easy. In some preferred embodiments, _TB1 is, for example, 90 ° C. or lower, more preferably 70 ° C. or lower, still more preferably 60 ° C. or lower, and particularly preferably 55 ° C. or lower (eg, 50 ° C. or lower).

From the viewpoint of facilitating the effect by appropriately setting _TB1 , the total amount of the monomer S1 and the (meth) acrylic monomer in all the monomer components for preparing the polymer (B) is, for example, 50 weight by weight. % Or more, 70% by weight or more, 85% by weight or more, 90% by weight or more, 95% by weight or more, and substantially 100% by weight.

The glass transition temperature TB of the polymer ( _B ) used in the technique disclosed herein is in the range of −20 ° C. to 5 ° C. When the TB of the polymer ( _B ) is 5 ° C. or lower, the mobility (typically, temperature-sensitive motility) of the polymer (B) is improved, and the adhesive strength can be greatly increased. In some preferred embodiments, the TB of the polymer ( _B ) may be below 0 ° C, below −5 ° C, or below −10 ° C. Further, when _TB is -20 ° C or higher, the polymer (B) unevenly distributed on the surface side of the pressure-sensitive adhesive layer at the time of sticking to the adherend contributes to a decrease in initial adhesive strength, resulting in light peelability at the initial stage of sticking. Tends to be better. In some preferred embodiments, the TB of the polymer ( _B ) may be -15 ° C or higher. By setting _TB in an appropriate range, it is possible to control the light peelability at the initial stage of application and the increase in adhesive strength after heating within a preferable range.

In some embodiments, the composition of the monomer component for preparing the polymer ( _B ) may be set such that TB1 is higher than _TB , i.e. _TB1 - _TB is greater than 0 ° C. can. According to such a composition, the effect of adjusting the mobility of the polymer (B) is likely to be suitably exhibited by the composition of the (meth) acrylic monomer contained in the monomer component. _TB1 - _TB may be, for example, about 40 ° C to 100 ° C, or may be about 50 ° C to 90 ° C. In some preferred embodiments, _TB1 - _TB is 45 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 55 ° C. or higher (eg, 58 ° C. or higher). Further, from the viewpoint of preferably expressing the effect of containing the polymer ( _B ), TB1- _TB is preferably 80 ° C. or lower, more preferably 70 ° C. or lower, still more preferably 65 ° C. or lower (for example, 62 ° C. or lower). be.

From the viewpoint of facilitating control of the mobility of the polymer (B) in the pressure-sensitive adhesive layer, in some embodiments, the composition of the monomer component for preparing the polymer (B) is the glass transition temperature T of the polymer (A). In relation to _A , _TB can be set to be 20 ° C. or higher higher than _TA , that is, _TB _−TA can be set to 20 ° C. or higher. In some preferred embodiments, TB _- _TA is, for example, 30 ° C. or higher, more preferably 40 ° C. or higher, still more preferably 50 ° C. or higher, 60 ° C. or higher, or 70 ° C. or higher. good. Further, from the viewpoint of increasing the adhesive strength, TB _- _TA may be, for example, 130 ° C. or lower, 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 80 ° C. or lower, still more preferably 65 ° C. or lower. It may be 55 ° C. or lower, or 45 ° C. or lower.

Examples of the (meth) acrylic monomer that can be used for the monomer raw material B include (meth) acrylic acid alkyl esters. The term "alkyl" as used herein refers to a chain-like (including linear and branched chain-like) alkyls (groups), and does not include the alicyclic hydrocarbon group described later. For example, one or more of the monomers exemplified above as the (meth) acrylic acid alkyl ester that can be used for the polymer (A) can be used as a constituent component of the monomer raw material B. In some preferred embodiments, the monomer raw material B is a (meth) acrylic acid C _4-12 alkyl ester (preferably a (meth) acrylic acid C _4-10 alkyl ester, eg, a (meth) acrylic acid C _6-10 alkyl ester. ) Can be contained. In some other embodiments, the monomer raw material B may contain at least one of a methacrylic acid C _1-18 alkyl ester (preferably a methacrylic acid C _1-14 alkyl ester, such as a methacrylic acid C _1-10 alkyl ester). .. The monomer raw material B may contain, as the (meth) acrylic monomer, one or more selected from, for example, MMA, n-butyl methacrylate (nBMA) and 2-ethylhexyl methacrylate (2EHMA).

Another example of the above (meth) acrylic monomer is a (meth) acrylic acid ester having an alicyclic hydrocarbon group. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl (meth) acrylate and the like can be used. In some embodiments, the monomer raw material B may contain, as the (meth) acrylic monomer, at least one selected from dicyclopentanyl methacrylate, isobornyl methacrylate and cyclohexyl methacrylate.

The content of the (meth) acrylic acid alkyl ester and the (meth) acrylic acid ester having an alicyclic hydrocarbon group in the monomer raw material B may be, for example, 10% by weight or more and 95% by weight or less, and may be 20% by weight. It may be 95% by weight or less, 30% by weight or more and 90% by weight or less, 40% by weight or more and 90% by weight or less, and 50% by weight or more and 85% by weight or less. May be good. From the viewpoint of easiness of increasing the adhesive force by heating, the use of (meth) acrylic acid alkyl ester may be advantageous. In some embodiments, the content of the (meth) acrylic acid ester having an alicyclic hydrocarbon group may be less than 50% by weight, less than 30% by weight, or less than 15% by weight of the monomer raw material B. It may be less than 10% by weight or less than 5% by weight. It is not necessary to use a (meth) acrylic acid ester having an alicyclic hydrocarbon group.

In some preferred embodiments, the (meth) acrylic monomer, which is a constituent of the monomer raw material B, may contain a monomer M2 having a homopolymer Tg of 50 ° C. or higher. In the polymer (B), by copolymerizing the monomer S1 and the monomer M2, the motility and mobility of the polyorganosiloxane structural portion with increasing temperature are suitably controlled, and the initial light peelability (reworkability) and heating are performed. It is easy to achieve both the later increase in adhesive strength. In some embodiments, the Tg of the homopolymer of the monomer M2 may be 60 ° C. or higher, 70 ° C. or higher, 80 ° C. or higher, or 90 ° C. or higher. The upper limit of Tg of the homopolymer of the monomer M2 is not particularly limited, but it is usually appropriate to be 200 ° C. or lower from the viewpoint of easiness of synthesizing the polymer (B). In some embodiments, the Tg of the homopolymer of the monomer M2 may be, for example, 180 ° C or lower, 150 ° C or lower, or 120 ° C or lower.

As the monomer M2, for example, among the (meth) acrylic monomers exemplified above, those in which the Tg of the homopolymer satisfies the condition can be used. For example, one or more monomers selected from the group consisting of (meth) acrylic acid alkyl esters and (meth) acrylic acid esters having an alicyclic hydrocarbon group can be used. As the (meth) acrylic acid alkyl ester, a methacrylic acid alkyl ester having an alkyl group having a carbon atom number in the range of 1 to 4 can be preferably adopted.

In the embodiment in which the monomer raw material B contains the monomer M2, the content of the monomer M2 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more of the monomer raw material B. However, it may be 25% by weight or more, or 30% by weight or more. In some embodiments, the content of the monomer M2 may be 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more of the monomer raw material B. But it may be. The content of the monomer M2 may be, for example, 90% by weight or less, usually 80% by weight or less, preferably 75% by weight or less, 70% by weight or less, and 65% by weight. It may be less than%. In some preferred embodiments, the content of the monomer M2 is 60% by weight or less (eg, 50% by weight or less, typically 42% by weight or less). In the polymer (B), the copolymerization ratio of the monomer M2 having a Tg of 50 ° C. or higher is limited to a predetermined value or less, so that the adhesive strength after heating is increased based on the mobility of the polymer (B) at around 50 ° C. It can be preferably realized. From the same viewpoint, the content of the monomer M2 in the monomer raw material B may be 35% by weight or less, 25% by weight or less, or 15% by weight or less (for example, 5% by weight or less).

The content of the monomer M2 is, for example, one or more monomers selected from the group consisting of the (meth) acrylic acid alkyl ester and the (meth) acrylic acid ester having the alicyclic hydrocarbon group. It can be preferably applied in an embodiment consisting of one or more monomers in which the monomer M2 is selected from a (meth) acrylic acid alkyl ester (for example, a methacrylic acid alkyl ester). As a preferred example of such an embodiment, there is an embodiment in which the above-mentioned monomer M2 is composed of MMA.

In some embodiments, the (meth) acrylic monomer may contain a monomer M3 in which the Tg of the homopolymer is less than 50 ° C (typically −20 ° C or higher and lower than 50 ° C). By using the monomer M3, it becomes easy to obtain a reinforcing film having both adhesive force and cohesive force in a well-balanced manner after the adhesive force is increased. From the viewpoint of facilitating the exertion of such an effect, the monomer M3 is preferably used in combination with the monomer M2.

As the monomer M3, for example, among the (meth) acrylic monomers exemplified above, those in which the Tg of the homopolymer satisfies the condition can be used. For example, one or more monomers selected from the group consisting of (meth) acrylic acid alkyl esters can be used.

In the embodiment in which the monomer raw material B contains the monomer M3, the content of the monomer M3 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more of the monomer raw material B. However, it may be 25% by weight or more, 30% by weight or more, or 35% by weight or more. Further, the content of the monomer M3 is usually preferably 70% by weight or less of the monomer raw material B, and may be 60% by weight or less, or 50% by weight or less. The content of the monomer M3 can be preferably applied, for example, in an embodiment in which the monomer M3 consists of one or more monomers selected from (meth) acrylic acid alkyl esters (eg, methacrylic acid alkyl esters).

In some aspects of the reinforcing film disclosed herein, the monomer raw material B preferably has a monomer content of a homopolymer having a Tg higher than 170 ° C. of 30% by weight or less. Here, the term "monomer content of X% by weight or less" in the present specification includes an embodiment in which the monomer content is 0% by weight, that is, an embodiment in which the monomer is substantially not contained, unless otherwise specified. It is a concept. Further, "substantially free" means that the above-mentioned monomer is not used at least intentionally. When the copolymerization ratio of the monomer having a Tg of homopolymer higher than 170 ° C. is high, the mobility of the polymer (B) tends to be insufficient, and it is difficult to increase the adhesive strength by heating to a temperature range higher than 50 ° C. Can be.

In some embodiments, the monomer raw material B preferably contains at least MMA as the (meth) acrylic monomer. According to the polymer (B) in which MMA is copolymerized, it is easy to obtain a reinforcing film having a large adhesive force after heating. The ratio of MMA to the total amount of the (meth) acrylic monomer contained in the monomer raw material B may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, and 30% by weight or more. However, it may be 40% by weight or more. Further, the ratio of MMA to the total amount of the monomer raw material B is usually 95% by weight or less, and in some preferred embodiments, the ratio of MMA to the total amount of the monomer raw material B is adhesion after heating. From the viewpoint of increasing the force, it may be 75% by weight or less, 65% by weight or less, 60% by weight or less, or 55% by weight or less (for example, 50% by weight or less).

As another example of the monomer that can be contained together with the monomer S1 as the monomer unit constituting the polymer (B), the carboxyl group-containing monomer, the acid anhydride group-containing monomer, and the hydroxyl group exemplified above as the monomers that can be used in the polymer (A). Monomer-containing monomer, epoxy group-containing monomer, cyano group-containing monomer, isocyanate group-containing monomer, amide group-containing monomer, monomer having a nitrogen atom-containing ring (N-vinyl cyclic amide, cyclic amide having a (meth) acryloyl group, succinimide skeleton Monomers, maleimides, itaconimides, etc.), (meth) acrylic acid aminoalkyls, vinyl esters, vinyl ethers, olefins, (meth) acrylic acid esters having aromatic hydrocarbon groups, heterocyclic-containing (meth) Examples thereof include acrylates, halogen atom-containing (meth) acrylates, and (meth) acrylic acid esters obtained from terpene compound derivative alcohols.

As yet another example of the monomer that can be contained together with the monomer S1 as the monomer unit constituting the polymer (B), ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol. Oxyalkylene di (meth) acrylates such as di (meth) acrylates, propylene glycol di (meth) acrylates, dipropylene glycol di (meth) acrylates, tripropylene glycol di (meth) acrylates; monomers having a polyoxyalkylene skeleton, such as A polyoxyalkylene chain such as polyethylene glycol or polypropylene glycol has a polymerizable functional group such as a (meth) acryloyl group, a vinyl group or an allyl group at one end, and an ether structure (alkyl ether, aryl ether, etc.) at the other end. Polymerizable polyoxyalkylene ethers (such as arylalkyl ethers); methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, (meth) acrylic. (Meta) Acrylic acid alkoxyalkyls such as ethoxypropyl acid; Salts such as (meth) acrylic acid alkali metal salts; Polyvalent (meth) acrylates such as trimethyl propanthry (meth) acrylic acid esters: Vinylidene chloride, (meth) Vinyl halide compounds such as -2-chloroethyl acrylate; oxazolin group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline and 2-isopropenyl-2-oxazoline; (meth). ) Acryloyl azilysin, aziridin group-containing monomers such as (meth) acrylate-2-aziridinylethyl; (meth) acrylate-2-hydroxyethyl, (meth) acrylate-2-hydroxypropyl, lactones and (meth). ) Hydroxyl-containing vinyl monomer such as an adduct with -2-hydroxyethyl acrylate; Fluorine-containing vinyl monomer such as fluorine-substituted (meth) acrylic acid alkyl ester; Containing reactive halogen such as 2-chloroethyl vinyl ether and monochloroethyl vinyl acetate Vinyl monomer; contains organic silicon such as vinyl trimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane. Vinyl-containing monomers; In addition, macromonomers having a radically polymerizable vinyl group at the terminal of a monomer polymerized with a vinyl group; and the like can be mentioned. These can be copolymerized with the monomer S1 alone or in combination of two or more.

In some embodiments, the polymer (B) may preferably be one that does not have a functional group that causes a cross-linking reaction with the polymer (A). In other words, the polymer (B) is preferably contained in the pressure-sensitive adhesive layer in a form that is not chemically bonded to the polymer (A). The pressure-sensitive adhesive layer containing the polymer (B) in such a form has good mobility of the polymer (B) at the time of heating, and is suitable for improving the adhesion increase ratio. The functional group that causes a cross-linking reaction with the polymer (A) may differ depending on the type of the functional group of the polymer (A), and may be, for example, an epoxy group, an isocyanate group, a carboxy group, an alkoxysilyl group, an amino group or the like. ..

The Mw of the polymer (B) is not particularly limited. The Mw of the polymer (B) may be, for example, 1000 or more, and may be 5000 or more. In some preferred embodiments, the Mw of the polymer (B) is 10,000 or more, more preferably 12,000 or more, and 15,000 or more, from the viewpoint of preferably exhibiting an increase in adhesive strength after heating. It may be 20,000 or more, 22,000 or more, or 25,000 or more. In some other embodiments, the Mw of the polymer (B) may be 30,000 or more, 50,000 or more, or 70,000 or more. The upper limit of Mw of the polymer (B) is, for example, 500,000 or less, may be 350,000 or less, may be 200,000 or less, or may be 150,000 or less. In some preferred embodiments, the Mw of the polymer (B) is 100,000 from the viewpoint of adjusting the compatibility and mobility in the pressure-sensitive adhesive layer to an appropriate range and preferably exhibiting low tackiness at the initial stage of application. It is more preferably 80,000 or less, still more preferably 60,000 or less, particularly preferably 40,000 or less (for example, 30,000 or less), and may be 25,000 or less, further 20 It may be 000 or less. By setting the Mw of the polymer (B) to an appropriate range, it is easy to obtain a pressure-sensitive adhesive having both light peelability and adhesive strength increase at the initial stage of application.

In some preferred embodiments, the Mw of the polymer (B) is preferably lower than the Mw of the polymer (A). This makes it easier to realize a reinforcing film that achieves both good reworkability at the initial stage of application and an increase in adhesive strength after heating. In some embodiments, the Mw of the polymer (B) may be, for example, 0.8 times or less, 0.75 times or less, 0.5 times or less, 0 times the Mw of the polymer (A). It may be 3 times or less. In some preferred embodiments, the ratio of Mw _B of the polymer ( _B ) to Mw _A of the polymer ( _A ) is 0.3 or less, more preferably 0.2 or less, still more preferred. Is 0.1 or less, particularly preferably 0.06 or less (for example, 0.05 or less). The ratio (Mw _B / Mw _A ) is, for example, 0.010 or more, preferably 0.020 or more, more preferably 0.03 or more, and further preferably 0.04 or more. By setting the Mw of the polymer (A) and the Mw of the polymer (B) in an appropriate range, the effects of the techniques disclosed herein can be better realized. In some other embodiments, the Mw of the polymer (B) may be 0.03 times or less (eg, 0.02 times or less) the Mw of the polymer (A).

The polymer (B) can be produced, for example, by polymerizing the above-mentioned monomer by a known method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or a photopolymerization method.

A chain transfer agent can be used as needed to adjust the molecular weight of the polymer (B). Examples of chain transfer agents used include octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, compounds having a mercapto group such as α-thioglycerol; thioglycolic acid, methyl thioglycolate, etc. Ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene Examples thereof include thioglycolic acid esters of glycol, thioglycolic acid esters of neopentyl glycol, thioglycolic acid esters such as pentaerythritol thioglycolic acid ester; α-methylstyrene dimer; and the like.

The amount of the chain transfer agent used is not particularly limited, but is usually 0.05 parts by weight to 20 parts by weight, preferably 0.1 parts by weight to 15 parts by weight, based on 100 parts by weight of the monomer. It is more preferably contained in an amount of 0.2 parts by weight to 10 parts by weight. By adjusting the amount of the chain transfer agent added in this way, the polymer (B) having a suitable molecular weight can be obtained. Chain transfer agents can be used alone or in combination of two or more.

As a means for adjusting the molecular weight of the polymer (B), various conventionally known means including the use of the chain transfer agent can be used alone or in combination as appropriate. The same applies to the molecular weight of the polymer (A). Non-limiting examples of such means include selection of polymerization method, selection of type and amount of polymerization initiator, selection of polymerization temperature, selection of type and amount of polymerization solvent in solution polymerization method, and light weight. Legal selection of light irradiation intensity, etc. are included. A person skilled in the art can understand how to obtain a polymer having a desired molecular weight based on the description of the present specification including the specific examples described later and the common general knowledge as of the filing of the present application.

In the reinforcing film disclosed herein, the amount of the polymer (B) used can be, for example, 0.1 part by weight or more with respect to 100 parts by weight of the polymer (A) used, and a higher effect (preferably). From the viewpoint of obtaining (light peelability at the initial stage of application), 0.5 parts by weight or more is preferable, 1 part by weight or more is more preferable, 1.5 parts by weight or more is further preferable, and 2 parts by weight or more may be used. In some embodiments, the amount of the polymer (B) used may be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more, from the viewpoint of improving reworkability. .. Further, the amount of the polymer (B) used with respect to 100 parts by weight of the polymer (A) may be, for example, 75 parts by weight or less, 30 parts by weight or less, 10 parts by weight or less, and 8 parts by weight or less. But it may be. From the viewpoint of suitably realizing the desired increase in adhesive strength, in some preferred embodiments, the amount of the polymer (B) used with respect to 100 parts by weight of the polymer (A) is 5 parts by weight or less, more preferably 4 parts by weight. Parts or less, more preferably 3 parts by weight or less, and particularly preferably 2.5 parts by weight or less. In some other preferred embodiments, the amount of the polymer (B) used relative to 100 parts by weight of the polymer (A) is 1.5 parts by weight or less (eg, 1.2 parts by weight or less). By setting the amount of the polymer (B) to be in the above range, it is easy to realize good bending recovery and bending holding force. In addition, it is possible to better achieve both the light peelability at the initial stage of application and the adhesive strength increasing property.

The pressure-sensitive adhesive layer may contain a polymer (arbitrary polymer) other than the polymer (A) and the polymer (B), if necessary, as long as the performance of the reinforcing film disclosed herein is not significantly impaired. The amount of such arbitrary polymer used is usually 20% by weight or less of the total polymer component contained in the pressure-sensitive adhesive layer, and may be 15% by weight or less, or 10% by weight or less. In some embodiments, the amount of the optional polymer used may be 5% by weight or less of the total polymer component, 3% by weight or less, or 1% by weight or less. The pressure-sensitive adhesive layer may be substantially free of polymers other than the polymer (A) and the polymer (B).

(Crosslinking agent)
A cross-linking agent may be used for the pressure-sensitive adhesive layer, if necessary, for the purpose of adjusting the cohesive force or the like. As the cross-linking agent, a cross-linking agent known in the field of adhesives can be used. Examples thereof include a cross-linking agent, an alkyl etherified melamine-based cross-linking agent, a metal chelate-based cross-linking agent, and the like. An isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, and a metal chelate-based cross-linking agent can be preferably used. An isocyanate-based cross-linking agent can be preferably used as a cross-linking agent that preferably achieves both bending recovery and bending holding power. The cross-linking agent may be used alone or in combination of two or more.

As the isocyanate-based cross-linking agent, polyfunctional isocyanate (a compound having an average of two or more isocyanate groups per molecule, including one having an isocyanurate structure) can be preferably used. The isocyanate-based cross-linking agent may be used alone or in combination of two or more.

Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates and the like.
Specific examples of aliphatic polyisocyanes include 1,2-ethylene diisocyanate; 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, 1,4-tetramethylene diisocyanate and other tetramethylene diisocyanates; 1,2. -Hexamethylene diisocyanate such as hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate; Examples thereof include 2-methyl-1,5-pentanediisocyanate, 3-methyl-1,5-pentanediisocyanate, and lysine diisocyanate.

Specific examples of the alicyclic polyisocyanates include isophorone diisocyanates; 1,2-cyclohexyldiisocyanates, 1,3-cyclohexyldiisocyanates, 1,4-cyclohexyldiisocyanates and other cyclohexyldiisocyanates; 1,2-cyclopentyldiisocyanates, 1,3. -Cyclopentyl diisocyanate such as cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and the like.

Specific examples of aromatic polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate. , 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate , 4,4'-Diphenylpropane diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate , Xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate and the like.

As a preferable polyfunctional isocyanate, a polyfunctional isocyanate having an average of 3 or more isocyanate groups per molecule is exemplified. Such trifunctional or higher functional isocyanates are addition reactions of bifunctional or trifunctional or higher functional isocyanate multimers (eg, dimers or trimers), derivatives (eg, polyhydric alcohols and two or more molecules of polyfunctional isocyanates). Product), polymer, etc. For example, diphenylmethane diisocyanate dimer or trimeric, hexamethylene diisocyanate isocyanurate (isocyanurate structure trimer adduct), reaction product of trimethylolpropane and tolylene diisocyanate, trimethylolpropane and hexa. Reaction product with methylene diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, trimethylolpropane adduct of isophorone diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester poly Examples thereof include isocyanates, additions of these to various polyols, and polyfunctional isocyanates such as polyisocyanates polyfunctionalized with isocyanurate bonds, burette bonds, allophanate bonds, and the like.

As commercial products of the above-mentioned polyfunctional isocyanate, the product name "Duranate TPA-100" manufactured by Asahi Kasei Chemicals Co., Ltd., the product name "Coronate L" manufactured by Tosoh Co., Ltd., "Coronate HL", "Coronate HK", and "Coronate" Examples thereof include "HX", "Coronate 2096", trade names "Takenate D110N", "Takenate D120N", "Takenate D140N", and "Takenate D160N" manufactured by Mitsui Chemicals, Inc.

Examples of the epoxy-based cross-linking agent include bisphenol A, epichlorohydrin-type epoxy-based resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, and trimethyl propanetri. Examples include glycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane. Can be done. These can be used alone or in combination of two or more.

Examples of the metal chelate compound include aluminum, iron, tin, titanium, nickel and the like as metal components, and acetylene, methyl acetoacetate, ethyl lactate and the like as chelate components. These can be used alone or in combination of two or more.

The amount used when the cross-linking agent is used is not particularly limited, and may be, for example, an amount exceeding 0 parts by weight with respect to 100 parts by weight of the polymer (A). The amount of the cross-linking agent used can be, for example, 0.01 parts by weight or more, preferably 0.05 parts by weight or more, based on 100 parts by weight of the polymer (A). As the amount of the cross-linking agent used increases, the adhesive strength at the initial stage of application is suppressed, and the reworkability tends to be improved. It tends to be excellent in bending recovery and workability. In some embodiments, the amount of the cross-linking agent used per 100 parts by weight of the polymer (A) may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight. It may be the above. On the other hand, from the viewpoint of appropriately allowing the mobility of the polymer (B) to obtain an increase in adhesive strength after heating, the amount of the cross-linking agent used with respect to 100 parts by weight of the polymer (A) is usually 15 parts by weight or less. Is appropriate, and may be 10 parts by weight or less, or 5 parts by weight or less.

The technique disclosed herein can be preferably carried out in an embodiment in which at least an isocyanate-based cross-linking agent is used as the cross-linking agent. From the viewpoint of achieving both good reworkability at the initial stage of application and increase in adhesive strength after heating, the amount of the isocyanate-based cross-linking agent used with respect to 100 parts by weight of the polymer (A) is, for example, 0.01 parts by weight in some embodiments. It can be more than 0.05 parts by weight, more preferably 0.07 parts by weight or more, and may be 0.10 parts by weight or more, and 0.15 parts by weight or more (for example, 0.20 parts by weight). It may be more than a part). By increasing the amount of the isocyanate-based cross-linking agent used, an appropriate cohesive force and elastic modulus can be obtained, and bending recovery and processability tend to be excellent. The amount of the isocyanate-based cross-linking agent used with respect to 100 parts by weight of the polymer (A) can be, for example, 5 parts by weight or less, preferably less than 1.0 part by weight, more preferably less than 0.5 parts by weight, and further. It is preferably less than 0.3 parts by weight, particularly preferably less than 0.2 parts by weight (for example, 0.15 parts by weight or less). As a result, the cohesive force of the pressure-sensitive adhesive, and thus the elastic modulus (typically, the surface elastic modulus) is appropriately lowered, a good bending holding force can be obtained, and an increase in the adhesive force after heating can be easily obtained.

Although not particularly limited, when an isocyanate-based cross-linking agent is used in a configuration in which the pressure-sensitive adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the molar ratio of the isocyanate group contained in the pressure-sensitive adhesive layer to the hydroxyl group ([NCO] / [ OH]) can be, for example, 0.001 or more. By increasing the amount of the isocyanate-based cross-linking agent used for the hydroxyl group-containing monomer in this way, the elastic modulus (typically, the surface elastic modulus) of the pressure-sensitive adhesive tends to be in a suitable range, and the bending recovery property tends to be improved. It also tends to be excellent in workability. In some preferred embodiments, the molar ratio ([NCO] / [OH]) is 0.002 or greater, more preferably 0.004 or greater, still more preferably 0.006 or greater (eg 0.007 or greater). It may be 0.010 or more, 0.020 or more, or 0.030 or more. Further, the molar ratio ([NCO] / [OH]) can be, for example, 1.0 or less, and may be 0.10 or less. By limiting the molar ratio to a predetermined value or less, a crosslinked structure suitable for greatly increasing the adhesive force after heating with respect to the adhesive force at the initial stage of application can be preferably formed. In some preferred embodiments, the molar ratio ([NCO] / [OH]) is 0.030 or less, more preferably 0.015 or less, still more preferably 0.012 or less (eg 0.009 or less). Yes, it may be 0.005 or less. In the pressure-sensitive adhesive layer, the isocyanate group and the hydroxyl group may exist in a state where at least a part thereof is chemically bonded (crosslinked). More specifically, the isocyanate group may exist in a state of being chemically bonded (crosslinked) with the hydroxyl group. On the other hand, a part of the hydroxyl group may be chemically bonded to the isocyanate group, and the other part may be present in a state where it is not chemically bonded (crosslinked) to the isocyanate group.

In some preferred embodiments, the pressure-sensitive adhesive layer comprises a catalyst. The catalyst may be added for the purpose of promoting the curing of the pressure-sensitive adhesive layer during the formation of the pressure-sensitive adhesive layer, typically for the purpose of more effectively advancing any of the above-mentioned cross-linking reactions. Therefore, the catalyst is also referred to as a curing catalyst or a cross-linking catalyst. By adding a catalyst, initial curing is promoted, and side reactions that cause bubbles on the surface of the pressure-sensitive adhesive layer can be suppressed. Examples of the catalyst include organic metal-based compounds such as iron-based catalysts, tin-based catalysts, titanium-based catalysts, zirconium-based catalysts, lead-based catalysts, cobalt-based catalysts, and zinc-based catalysts, and tertiary amine compounds. These can be used alone or in combination of two or more. Among them, an iron-based catalyst and a tin-based catalyst are preferable, and an iron-based catalyst is particularly preferable, from the viewpoint of the balance between the reaction rate and the pot life.

Examples of the iron-based catalyst include iron acetylacetonate and iron 2-ethylhexanoate. The iron-based catalyst may be used alone or in combination of two or more.

Examples of the tin-based catalyst include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin methoxyde, tributyltin acetate, and triethyltinethoxydo. Examples thereof include tributyl tin ethoxydo, dioctyl tin oxide, dioctyl tin dilaurate, tributyl tin chloride, tributyl tin trichloroacetate, tin 2-ethylhexanoate and the like. The tin-based catalyst may be used alone or in combination of two or more.

The amount of the catalyst used is not particularly limited and can be, for example, 0.0001 parts by weight or more, preferably 0.001 parts by weight or more, and more preferably 0.003 parts by weight with respect to 100 parts by weight of the polymer (A). It is 0 parts by weight or more, more preferably 0.006 parts by weight or more, and particularly preferably 0.008 parts by weight or more. By using an appropriate amount of catalyst, the generation of bubbles from the pressure-sensitive adhesive layer is suppressed, and a smooth pressure-sensitive adhesive surface can be easily obtained. Further, the amount of the catalyst used with respect to 100 parts by weight of the polymer (A) can be, for example, 1 part by weight or less, and may be 0.1 part by weight or less. In some preferred embodiments, the amount of catalyst used per 100 parts by weight of the polymer (A) is 0.03 parts by weight or less, more preferably 0.02 parts by weight or less, still more preferably 0.01 parts by weight or less. Yes, it may be 0.005 part by weight or less. By appropriately limiting the content of the catalyst with respect to 100 parts by weight of the polymer (A), it is easy to realize a suitable increase in adhesive strength.

Although not particularly limited, when a catalyst is used in a configuration in which the pressure-sensitive adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the amount of the catalyst used is the molar ratio of the catalyst and the hydroxyl group contained in the pressure-sensitive adhesive layer ([catalyst]. / [OH]) can be, for example, 1.0 × 10 ^-6 or more, preferably 1.0 × 10 ^-5 or more, more preferably 1.0 × 10 ^-4 or more, still more preferable. Is an amount of 2.0 × 10 ^-4 or more, particularly preferably 3.0 × 10 ^-4 or more. By using an appropriate amount of catalyst, the generation of bubbles from the pressure-sensitive adhesive layer is suppressed, and a smooth pressure-sensitive adhesive surface can be easily obtained. Further, the molar ratio ([catalyst] / [OH]) can be, for example, 5.0 × ^10-2 or less, and may be 5.0 × 10 ^-3 or less. In some preferred embodiments, the molar ratio ([catalyst] / [OH]) is 3.0 × 10 ^-3 or less, more preferably 1.0 × 10 ^-3 or less, still more preferably 5.0. It may be × 10 ^-4 or less, and may be 3.0 × 10 ^-4 or less. By appropriately limiting the content of the catalyst, it is easy to realize a suitable increase in adhesive strength.

(Adhesive-imparting resin)
The pressure-sensitive adhesive layer may contain a pressure-sensitive adhesive resin, if necessary. The tackifier resin is not particularly limited, and for example, a rosin-based tackifier resin, a terpene-based tackifier resin, a phenol-based tackifier resin, a hydrocarbon-based tackifier resin, a ketone-based tackifier resin, a polyamide-based tackifier resin, etc. Examples thereof include an epoxy-based adhesive-imparting resin and an elastomer-based adhesive-imparting resin. The tackifier resin may be used alone or in combination of two or more.

The content of the adhesive-imparting resin is not particularly limited, and can be set so as to exhibit appropriate adhesive performance according to the purpose and application. The content of the tackifier resin with respect to 100 parts by weight of the polymer (A) (when two or more kinds of tackifier resins are included, the total amount thereof) can be, for example, about 5 to 500 parts by weight. Further, the technique disclosed herein can be preferably carried out in an embodiment in which the amount of the tackifier resin used is limited. For example, the content of the tackifier resin with respect to 100 parts by weight of the polymer (A) can be less than 20 parts by weight, may be less than 10 parts by weight, may be less than 3 parts by weight, and may be less than 1 part by weight ( It may be from 0 part by weight to less than 1 part by weight), and in some embodiments, the pressure-sensitive adhesive layer does not substantially contain the tack-imparting resin.

In addition, the pressure-sensitive adhesive layer in the technique disclosed herein is a leveling agent, a plasticizer, a softening agent, a colorant (dye, pigment, etc.), a filler, and an antistatic agent, to the extent that the effects of the present invention are not significantly impaired. , Anti-aging agents, UV absorbers, antioxidants, light stabilizers, preservatives and the like, which may contain known additives that can be used as adhesives, if necessary.

The pressure-sensitive adhesive layer constituting the reinforcing film disclosed herein may be a cured layer of the pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer is formed by applying (for example, coating) a pressure-sensitive adhesive composition such as a water-dispersed type, a solvent type, a photo-curing type, or a hot-melt type to an appropriate surface, and then appropriately performing a curing treatment. obtain. When performing two or more types of curing treatments (drying, crosslinking, polymerization, cooling, etc.), these can be performed simultaneously or in multiple steps. In a pressure-sensitive adhesive composition using a partial polymer (polymer syrup) of a monomer raw material, a final copolymerization reaction is typically performed as the above-mentioned curing treatment. That is, the partial polymer is subjected to a further copolymerization reaction to form a complete polymer. For example, in the case of a photocurable pressure-sensitive adhesive composition, light irradiation is performed. If necessary, hardening treatment such as crosslinking and drying may be carried out. For example, when it is necessary to dry with a photocurable pressure-sensitive adhesive composition, it is preferable to perform photo-curing after drying. In the pressure-sensitive adhesive composition using a complete polymer, typically, as the above-mentioned curing treatment, treatments such as drying (heat drying) and cross-linking are carried out as necessary.

The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be, for example, 6 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be 8 μm or greater, 10 μm or greater, 15 μm or greater, 20 μm or greater, or greater than 20 μm. As the thickness of the pressure-sensitive adhesive layer increases, the pressure-sensitive adhesive strength tends to increase after heating. Further, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less. It may be as follows. The fact that the thickness of the pressure-sensitive adhesive layer is not too large can be advantageous from the viewpoints of reducing the thickness of the reinforcing film and preventing cohesive failure of the pressure-sensitive adhesive layer. A reinforcing film having an adhesive layer having a thickness within the above range can have a good balance of adhesive properties such as adhesive strength, bending recovery property, and bending holding force. In the case of a reinforcing film having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on the first and second surfaces of the base material, the thickness of the above-mentioned pressure-sensitive adhesive layer is at least the thickness of the first pressure-sensitive adhesive layer. Can be applied to. The thickness of the second pressure-sensitive adhesive layer may be selected from the same range. Further, in the case of a base material-less reinforcing film, the thickness of the reinforcing film coincides with the thickness of the pressure-sensitive adhesive layer.

<Supporting base material>
The reinforcing film according to some aspects may be in the form of a substrate-based pressure-sensitive adhesive sheet having an pressure-sensitive adhesive layer on one or both sides of a supporting base material. The material of the supporting base material is not particularly limited, and can be appropriately selected depending on the purpose of use, the mode of use, and the like of the reinforcing film. Non-limiting examples of base materials that can be used include resin films such as plastic films; foam sheets made of foams such as polyurethane foams, polyethylene foams, and polychloroprene foams; various fibrous substances (linen, cotton, etc.). Natural fibers, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) Woven fabrics and non-woven fabrics made by single or blended spinning; papers such as Japanese paper, high-quality paper, kraft paper, crepe paper, etc. ; Metal foil such as aluminum foil and copper foil; and the like. A base material having a composite structure thereof may be used. Examples of such a composite base material include a base material having a structure in which a metal foil and the above plastic film are laminated, a plastic base material reinforced with an inorganic fiber such as glass cloth, and the like.

As the base material of the reinforcing film disclosed here, various film base materials can be preferably used. The film base material may be a porous base material such as a foam film or a non-woven fabric sheet, or may be a non-porous base material, and may be a porous layer and a non-porous layer. It may be a base material having a laminated structure. In some embodiments, as the film substrate, a film containing an independently shape-maintainable (self-supporting or independent) resin film as a base film can be preferably used. As used herein, the term "resin film" means a resin film (of voidless) having a non-porous structure and typically containing substantially no bubbles. Therefore, the resin film is a concept that is distinguished from foam films and non-woven fabrics. As the resin film, one that can independently maintain its shape (self-supporting or independent) can be preferably used. The resin film may have a single-layer structure or a multi-layer structure having two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polyamide (PA) such as polyester, polyolefin, nylon 6, nylon 66, and partially aromatic polyamide, polyimide (PI), polyamideimide (PAI), and polyetheretherketone (PEEK). ), Polyethersulfone (PES), Polyphenylene sulfide (PPS), Polycarbonate (PC), Polyurethane (PU), Ethylene-vinyl acetate copolymer (EVA), Polytetrafluoroethylene (PTFE) and other fluororesins and acrylic resins. , Polyacrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride and the like can be used. The resin film may be formed by using a resin material containing one kind of such a resin alone, or may be formed by using a resin material in which two or more kinds are blended. good. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Preferable examples of the resin material constituting the resin film include polyimide-based resin, polyester-based resin, PPS resin, and polyolefin-based resin. Here, the polyimide-based resin refers to a resin containing polyimide in a proportion of more than 50% by weight. Similarly, the polyester-based resin refers to a resin containing polyester in a proportion of more than 50% by weight, and the PPS resin refers to a resin containing PPS in a proportion of more than 50% by weight, and is a polyolefin-based resin. Refers to a resin containing polyolefin in a proportion of more than 50% by weight.

Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate and the like.

As the polyolefin resin, one kind of polyolefin can be used alone, or two or more kinds of polyolefins can be used in combination. The polyolefin can be, for example, a homopolymer of an α-olefin, a copolymer of two or more kinds of α-olefins, a copolymer of one or more kinds of α-olefins and another vinyl monomer, and the like. Specific examples include polyethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR), and ethylene-propylene-. Examples thereof include a butene copolymer, an ethylene-butene copolymer, an ethylene-vinyl alcohol copolymer, and an ethylene-ethyl acrylate copolymer. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, medium density polyethylene (MDPE). Examples thereof include a film, a high-density polyethylene (HDPE) film, a polyethylene (PE) film in which two or more kinds of polyethylene (PE) are blended, a PP / PE blend film in which polypropylene (PP) and polyethylene (PE) are blended, and the like.

Specific examples of the resin film that can be preferably used as the base film of the reinforcing film disclosed herein include PI film, PET film, PEN film, PPS film, PEEK film, CPP film and OPP film.

Known resin films include light stabilizers, antioxidants, antistatic agents, colorants (dyees, pigments, etc.), fillers, slip agents, antiblocking agents, etc., as long as the effects of the present invention are not significantly impaired. Additives can be added as needed. The blending amount of the additive is not particularly limited and can be appropriately set according to the purpose and the like.

The method for manufacturing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately adopted.

The base material may be substantially composed of such a base film. Alternatively, the base material may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjusting layer (for example, a colored layer and an antireflection layer), a printing layer or a laminating layer for imparting a desired appearance to a substrate, an antistatic layer, an undercoat layer, and a peeling layer. Such as a surface treatment layer.

The thickness of the base material is not particularly limited and can be selected according to the purpose and mode of use of the reinforcing film. The thickness of the substrate can be, for example, 1000 μm or less. In some embodiments, the thickness of the substrate may be, for example, 500 μm or less, 300 μm or less, or 250 μm or less, from the viewpoint of handleability and processability of the reinforcing film. It may be 200 μm or less. From the viewpoint of miniaturization and weight reduction of the product to which the reinforcing film is applied, in some embodiments, the thickness of the base material may be, for example, 160 μm or less, 130 μm or less, or 100 μm or less. It may be 90 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the base material becomes smaller, the flexibility of the reinforcing film and the followability to the surface shape of the adherend tend to improve. Further, from the viewpoint of handleability, processability and the like, the thickness of the base material may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 25 μm or more. In some embodiments, the thickness of the substrate may be, for example, 30 μm or more, 35 μm or more, 55 μm or more, 70 μm or more, 75 μm or more, 90 μm or more, 120 μm or more. .. For example, in the reinforcing film, a base material having a thickness of 30 μm or more can be preferably adopted.

The first surface of the base material is a conventionally known surface such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of an undercoat layer by applying a primer, if necessary. It may be treated. Such a surface treatment may be a treatment for improving the anchoring property of the pressure-sensitive adhesive layer on the substrate. For example, in a reinforcing film provided with a base material containing a resin film as a base film, a base material subjected to such anchoring property improving treatment can be preferably adopted. The above surface treatments can be applied alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. Other treatments that can be applied to the first surface of the substrate as needed include antistatic layer forming treatments, colored layer forming treatments, printing treatments and the like.

When the reinforcing film disclosed herein is in the form of a single-sided pressure-sensitive adhesive sheet having an adhesive layer only on the first surface of the base material, the second side of the base material may be subjected to peeling treatment or antistatic treatment, if necessary. Conventionally known surface treatment such as treatment may be applied. For example, by surface-treating the back surface of the base material with a release treatment agent (typically, by providing a release layer with a release treatment agent), the rewinding force of the reinforcing film in the form of being wound in a roll shape. Can be lightened. As the stripping agent, a silicone-based stripping agent, a long-chain alkyl-based stripping agent, an olefin-based stripping agent, a fluorine-based stripping agent, a fatty acid amide-based stripping agent, molybdenum sulfide, silica powder, or the like can be used. .. In addition, for the purpose of improving printability, reducing light reflectivity, improving stackability, etc., the second surface of the base material is subjected to treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, and alkali treatment. It may have been done. Further, in the case of the double-sided adhesive sheet, the second surface of the base material is subjected to the same surface treatment as those exemplified above as the surface treatment that can be applied to the first surface of the base material, if necessary. May be good. The surface treatment applied to the first surface of the base material and the surface treatment applied to the second surface may be the same or different.

<Characteristics of reinforcing film>
In the reinforcing film disclosed herein, it is preferable that the initial adhesive force N ₂₃ measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes is limited to a predetermined value or less. In some embodiments, the adhesive force N ₂₃ is preferably, for example, less than 500 gf / 25 mm, more preferably less than 400 gf / 25 mm, still more preferably less than 300 gf / 25 mm, particularly preferably 250 gf / 25 mm or less (eg 200 gf /). 25 mm or less), and may be 150 gf / 25 mm or less. A low adhesive force N ₂₃ is preferable from the viewpoint of reworkability. The lower limit of the adhesive force N ₂₃ is not particularly limited and may be, for example, 1 gf / 25 mm or more. The adhesive strength N ₂₃ is usually preferably 10 gf / 25 mm or more from the viewpoint of sticking workability to the adherend and prevention of positional deviation before the adhesive strength increases. From the viewpoint of improving the adhesive strength after heating, in some embodiments, the adhesive strength N ₂₃ may be, for example, 20 gf / 25 mm or more, 50 gf / 25 mm or more, 80 gf / 25 mm or more, 100 gf / 25 mm or more. The above (for example, 150 gf / 25 mm or more) may be used.

The adhesive strength N ₂₃ [gf / 25 mm] is applied by crimping to a stainless steel (SUS) plate as an adherend and leaving it in an environment of 23 ° C. and 50% RH for 30 minutes, and then in the same environment (that is, at 23 ° C.). ), The peeling angle is 180 degrees, and the tensile speed is 300 mm / min. As the adherend, a SUS304BA plate is used. In the measurement, if necessary, an appropriate backing material (for example, a PET film having a thickness of about 25 μm) can be attached to the reinforcing film to be measured for reinforcement. More specifically, the adhesive strength N ₂₃ can be measured according to the method for measuring the initial adhesive strength described in Examples described later.

The reinforcing film disclosed herein has an adhesive strength that increases by heating, for example, an adhesive strength of N60 of 300 gf / 25 mm or more, that is, after being bonded to a stainless steel plate and held at ₆₀ ° C. for 60 minutes, at 23 ° C. It can indicate the adhesive strength to be measured. In some embodiments, it is appropriate that the adhesive force N ₆₀ is 400 gf / 25 mm or more and 500 gf / 25 mm or more. After the reinforcing film satisfying this characteristic is attached to the adherend, the adhesive strength is increased to a predetermined value or more by heating. According to the technique disclosed herein, it is possible to obtain a strong adhesive force by heating. In some preferred embodiments, the adhesive force N ₆₀ is 600 gf / 25 mm or more, more preferably 700 gf / 25 mm or more, 800 gf / 25 mm or more, or 900 gf / 25 mm or more. The upper limit of the adhesive strength N ₆₀ is not particularly limited. From the viewpoint of ease of manufacturing and economic efficiency of the reinforcing film, the adhesive strength N ₆₀ may be, for example, 3000 gf / 25 mm or less, 1500 gf / 25 mm or less, or 1000 gf / 25 mm or less in some embodiments.

The adhesive strength N ₆₀ [gf / 25 mm] is pressure-bonded to a SUS plate as an adherend and held in an environment of 60 ° C. for 60 minutes, and then left in an environment of 23 ° C. and 50% RH for 30 minutes, and then in the same environment. In, 180 ° peeling adhesive force is measured under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / min. As the adherend, a SUS304BA plate is used as in the case of the adhesive strength N ₂₃ . In the measurement, if necessary, an appropriate backing material (for example, a PET film having a thickness of about 25 μm) can be attached to the reinforcing film to be measured for reinforcement. More specifically, the adhesive strength N ₆₀ can be measured according to the method for measuring the adhesive strength after heating described in Examples described later.

The ratio of the adhesive force N ₆₀ [gf / 25 mm] to the adhesive force N ₂₃ [gf / 25 mm], that is, the adhesive force increase ratio N ₆₀ / N ₂₃ is not particularly limited, and in some embodiments, the N ₆₀ / N ₂₃ Is 15 or more, preferably 2.0 or more, more preferably 2.5 or more, still more preferably 3.0 or more (for example, 3.5 or more), and 5 It may be more than 0.0 (for example, more than 7.0). According to the reinforcing film having a large N ₆₀ / N ₂₃ , good reworkability is exhibited at the initial stage of application, and the adhesive strength can be greatly increased by subsequent heating or the like. The upper limit of N ₆₀ / N ₂₃ is not particularly limited, and is usually 100 or less. From the viewpoint of ease of manufacturing and economic efficiency of the reinforcing film, it may be 30 or less, 15 or less, or 10 or less. In some embodiments, N ₆₀ / N ₂₃ may be, for example, 5 or less, 3 or less, or 2 or less.

The post-heating adhesive force of the reinforcing film disclosed herein represents one characteristic of the reinforcing film, and does not limit the usage mode of the reinforcing film. In other words, the mode of use of the reinforcing film disclosed herein is not limited to the mode of heating at 60 ° C. for 60 minutes, for example, in the room temperature range (usually 20 ° C. to 30 ° C., typically 23 ° C. to 23 ° C.). It can also be used in a mode in which the treatment of heating to 25 ° C. or higher is not particularly performed. Even in such a usage mode, the adhesive strength is increased in a long period of time, and a strong bond can be realized. Further, the reinforcing film disclosed herein promotes an increase in adhesive strength by performing a heat treatment at an arbitrary timing after application at a temperature higher than 30 ° C (for example, about 50 to 70 ° C) or 60 ° C. be able to. The heating temperature in such a heat treatment is not particularly limited, and can be set in consideration of workability, economy, heat resistance of the base material of the reinforcing film and the adherend, and the like. The heating temperature may be, for example, less than 150 ° C., 120 ° C. or lower, 100 ° C. or lower, 80 ° C. or lower, or 70 ° C. or lower. Further, the heating temperature can be, for example, 40 ° C. or higher, 45 ° C. or higher, 50 ° C. or higher, 55 ° C. or higher, 60 ° C. or higher, or 70 ° C. or higher, 80 ° C. or higher, or 100 ° C. or higher. good. The heating time is not particularly limited, and may be, for example, 3 hours or less, 1 hour or less, 30 minutes or less, or 10 minutes or less. The heating time may be, for example, 1 minute or longer, 15 minutes or longer, 30 minutes or longer, or 1 hour or longer. Alternatively, the heat treatment may be performed for a longer period of time as long as the reinforcing film or the adherend is not significantly deteriorated by heat. The heat treatment may be performed at one time or may be performed in a plurality of times.

<Reinforcing film with base material>
When the reinforcing film disclosed herein is in the form of an adhesive sheet with a base material, the thickness of the reinforcing film may be, for example, 1000 μm or less, 600 μm or less, or 350 μm or less. It may be 250 μm or less. From the viewpoint of miniaturization, weight reduction, thinning, etc. of the product to which the reinforcing film is applied, the thickness of the reinforcing film may be, for example, 200 μm or less, even if it is 175 μm or less, in some embodiments. It may be 140 μm or less, 120 μm or less, or 100 μm or less (for example, less than 100 μm). Further, the thickness of the reinforcing film may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more from the viewpoint of handleability and the like. In some embodiments, the thickness of the reinforcing film may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the reinforcing film is not particularly limited.
The thickness of the reinforcing film means the thickness of the portion to be attached to the adherend. For example, in the reinforcing film 1 having the configuration shown in FIG. 1, it refers to the thickness from the adhesive surface 21A of the reinforcing film 1 to the second surface 10B of the base material 10, and does not include the thickness of the release liner 31.

The reinforcing film disclosed herein can be suitably implemented, for example, in an embodiment in which the thickness Ts of the supporting base material is larger than the thickness Ta of the pressure-sensitive adhesive layer, that is, the Ts / Ta is larger than 1. Although not particularly limited, Ts / Ta may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more. May be good. For example, due to the increase in Ts / Ta, there is a tendency that a good effect is easily exhibited even if the reinforcing film is made thinner. In some embodiments, Ts / Ta may be 2 or greater (eg, greater than 2), 2.5 or greater, or 2.8 or greater. Further, Ts / Ta may be, for example, 50 or less, or 20 or less. The Ts / Ta may be, for example, 10 or less, 8 or less, or 5 or less, from the viewpoint of facilitating the high adhesive strength after heating even if the reinforcing film is made thin.

The pressure-sensitive adhesive layer is preferably adhered to a supporting base material. Here, "sticking" means that in a reinforcing film whose adhesive strength has increased after being attached to an adherend, peeling occurs at the interface between the adhesive layer and the supporting base material when the reinforcing film is peeled from the adherend. It means that the pressure-sensitive adhesive layer exhibits sufficient anchoring property with respect to the supporting base material to the extent that it does not exist. According to the reinforcing film with a base material in which the pressure-sensitive adhesive layer is fixed to the support base material, the adherend and the support base material can be firmly integrated. As a preferred example of the reinforcing film in which the pressure-sensitive adhesive layer is adhered to the base material, peeling (anchor failure) between the pressure-sensitive adhesive layer and the supporting base material does not occur during the above-mentioned measurement of the adhesive force after heating. Examples include reinforcing films. A reinforcing film in which anchoring failure does not occur when measuring the adhesive force after heating is a suitable example corresponding to a reinforcing film in which the adhesive layer is adhered to a base material.

In the reinforcing film disclosed herein, for example, a liquid pressure-sensitive adhesive composition is brought into contact with the first surface of a base material, and the pressure-sensitive adhesive composition is cured on the first surface to form a pressure-sensitive adhesive layer. It can be preferably produced by a method including forming and in this order. Curing of the pressure-sensitive adhesive composition may involve one or more of drying, cross-linking, polymerization, cooling, etc. of the pressure-sensitive adhesive composition. According to the method of forming a pressure-sensitive adhesive layer by curing the liquid pressure-sensitive adhesive composition on the first surface of the base material, the cured pressure-sensitive adhesive layer is bonded to the first surface of the base material. Compared with the method of arranging the pressure-sensitive adhesive layer on the first surface, the anchoring property of the pressure-sensitive adhesive layer on the base material can be enhanced. Utilizing this, a reinforcing film in which the pressure-sensitive adhesive layer is adhered to the base material can be suitably manufactured.

In some embodiments, as a method of contacting the liquid pressure-sensitive adhesive composition with the first surface of the base material, a method of directly applying the pressure-sensitive adhesive composition to the first surface of the base material can be adopted. By bringing the first surface (adhesive surface) of the pressure-sensitive adhesive layer cured on the first surface of the base material into contact with the peeling surface, the second surface of the pressure-sensitive adhesive layer is fixed to the first surface of the base material. Moreover, it is possible to obtain a reinforcing film having a structure in which the first surface of the pressure-sensitive adhesive layer is in contact with the peeling surface. As the peeling surface, the surface of the peeling liner, the back surface of the base material that has been peeled off, or the like can be used.

Further, for example, in the case of a photocurable pressure-sensitive adhesive composition using a partial polymer (polymer syrup) of a monomer raw material, for example, the pressure-sensitive adhesive composition is applied to a peeling surface and then the applied pressure-sensitive adhesive composition is applied. By covering the object with the first surface of the base material, the uncured adhesive composition is brought into contact with the first surface of the base material, and in that state, it is sandwiched between the first surface of the base material and the peeled surface. The pressure-sensitive adhesive layer may be formed by irradiating the pressure-sensitive adhesive composition with light to cure the pressure-sensitive adhesive composition.

Note that the method exemplified above does not limit the manufacturing method of the reinforcing film disclosed here. In the production of the reinforcing film disclosed herein, an appropriate method capable of fixing the pressure-sensitive adhesive layer to the first surface of the base material can be used alone or in combination of two or more. Examples of such methods include a method of curing a liquid pressure-sensitive adhesive composition on the first surface of a substrate to form a pressure-sensitive adhesive layer as described above, and a method of forming a pressure-sensitive adhesive layer on the first surface of a substrate. Examples thereof include a method of applying a surface treatment that enhances the anchoring property. For example, when the anchoring property of the pressure-sensitive adhesive layer on the base material can be sufficiently improved by a method such as providing an undercoat layer on the first surface of the base material, the pressure-sensitive adhesive layer after curing is used as the first surface of the base material. A reinforcing film may be manufactured by a method of adhering to. Further, the anchorability of the pressure-sensitive adhesive layer to the base material can be improved by selecting the material of the base material and the composition of the pressure-sensitive adhesive. Further, by applying a temperature higher than room temperature to the reinforcing film having the pressure-sensitive adhesive layer on the first surface of the base material, the anchoring property of the pressure-sensitive adhesive layer on the base material can be enhanced. The temperature applied to enhance the anchoring property may be, for example, about 35 ° C. to 80 ° C., 40 ° C. to 70 ° C. or higher, or 45 ° C. to 60 ° C.

The reinforcing film disclosed herein is a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer provided on the first surface of the base material and a second pressure-sensitive adhesive layer provided on the second surface of the base material (that is,). In the form of a double-sided adhesive base-attached pressure-sensitive adhesive sheet), the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may have the same configuration or different configurations. When the composition of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is different, the difference may be, for example, a difference in composition or a difference in structure (thickness, surface roughness, formation range, formation pattern, etc.). For example, the second pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer that does not contain the polymer (B). Further, the surface of the second pressure-sensitive adhesive layer (second pressure-sensitive adhesive surface) may have a surface elastic modulus outside the range of 1 to 20 kPa (for example, more than 20 kPa) at 23 ° C., or may be 30 kPa or more.

<Reinforcing film with release liner>
The reinforcing film disclosed herein may take the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer is brought into contact with the release surface of the release liner. Accordingly, this specification may provide a reinforcing film with a release liner comprising any of the reinforcing films disclosed herein and a release liner having a release surface that abuts on the adhesive surface of the reinforcement film. ..

The thickness of the release liner is not particularly limited, but is usually about 5 μm to 200 μm. When the thickness of the release liner is within the above range, it is preferable because it is excellent in the workability of bonding to the pressure-sensitive adhesive layer and the workability of peeling off from the pressure-sensitive adhesive layer. In some embodiments, the thickness of the release liner may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Further, the thickness of the release liner may be, for example, 100 μm or less, or 80 μm or less, from the viewpoint of facilitating the release from the pressure-sensitive adhesive layer. If necessary, the release liner may be subjected to a known antistatic treatment such as a coating type, a kneading type, and a thin-film deposition type.

The release liner is not particularly limited, and is, for example, a release liner having a release layer on the surface of a liner base material such as a resin film or paper (paper on which a resin such as polyethylene is laminated) or a fluoropolymer. A release liner made of a resin film formed of a low adhesive material such as (polytetrafluoroethylene, etc.) or a polyolefin resin (polyethylene, polypropylene, etc.) can be used. Since the surface smoothness is excellent, a release liner having a release layer on the surface of the resin film as a liner base material or a release liner made of a resin film formed of a low adhesive material can be preferably adopted. The resin film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and is, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, or a vinyl chloride copolymer. Examples thereof include films, polyester films (PET films, PBT films, etc.), polyurethane films, ethylene-vinyl acetate copolymer films, and the like. For forming the peeling layer, for example, a silicone-based stripping agent, a long-chain alkyl-based stripping agent, an olefin-based stripping agent, a fluorine-based stripping agent, a fatty acid amide-based stripping agent, molybdenum sulfide, silica powder, or the like can be used. , A known stripping agent can be used. The use of a silicone-based stripping agent is particularly preferred.

The thickness of the peeling layer is not particularly limited, but usually about 0.01 μm to 1 μm is appropriate, and about 0.1 μm to 1 μm is preferable. The method for forming the release layer is not particularly limited, and a known method according to the type of the release treatment agent to be used can be appropriately adopted.

<Use>
The reinforcing film provided by this specification can exhibit good reworkability at the initial stage of being attached to the adherend, for example, so that it is possible to suppress a decrease in yield and to increase the height of the product containing the reinforcing film. Can contribute to quality improvement. Then, after the reinforcing film is attached to the adherend, the adhesive strength can be greatly increased by aging or heating. For example, the reinforcing film can be firmly adhered to the adherend by heating at an appropriate timing after being attached to the adherend. Taking advantage of these characteristics, the reinforcing film disclosed herein can be preferably used for the purpose of reinforcing members contained in various products in various fields.

The reinforcing film disclosed herein is, for example, an adherend in the form of an adhesive sheet with a substrate having an adhesive layer provided on at least the first surface of a film-like substrate having a first surface and a second surface. It can be preferably used as a reinforcing film which is attached to and reinforces the adherend. In such a reinforcing film, as the film base material, a film containing a resin film as a base film can be preferably used. Further, from the viewpoint of enhancing the reinforcing performance, it is preferable that the pressure-sensitive adhesive layer is adhered to the first surface of the film-like substrate.
For example, in optical members used in optical products and electronic members used in electronic products, advanced integration, miniaturization, weight reduction, and thinning are progressing, and a plurality of thin optical members having different linear expansion coefficients and thicknesses / Electronic members can be stacked. By attaching the reinforcing film as described above to such a member, it is possible to impart appropriate rigidity to the optical member / electronic member. Thereby, in the manufacturing process and / or the product after manufacturing, it is possible to suppress curl and bending caused by the stress that may occur between the plurality of members having different linear expansion coefficients and thicknesses.
Further, in the manufacturing process of optical products / electronic products, in the aspect of performing shape processing such as cutting on a thin optical member / electronic member as described above, processing is performed by attaching a reinforcing film to the member. It is possible to alleviate the local stress concentration on the optical member / electronic member and reduce the risk of cracks, cracks, peeling of laminated members, and the like. Handling a reinforcing member by attaching it to an optical member / electronic member also reduces local stress concentration during transportation, stacking, rotation, etc. of the member, and suppresses bending or bending due to the weight of the member. Can be useful.
Furthermore, devices such as optical products and electronic products containing the above-mentioned reinforcing film collide with flying objects when the device is dropped or placed under a heavy object at the stage of being used by consumers in the market. Even when unintentional stress is applied, such as in the case, the stress applied to the device can be relieved by including the reinforcing film in the device. Therefore, the inclusion of the reinforcing film in the device can improve the durability of the device.

Further, the reinforcing film disclosed herein can be preferably used, for example, in a manner of being attached to a member constituting various portable devices (portable devices). Here, "portable" means that it is not enough to be portable, but that an individual (standard adult) has a level of portability that is relatively easy to carry. do. Examples of portable devices here include mobile phones, smartphones, tablet PCs, notebook PCs, various wearable devices, digital cameras, digital video cameras, sound devices (portable music players, IC recorders, etc.), and calculators (portable music players, IC recorders, etc.). Calculators, etc.), mobile game devices, electronic dictionaries, electronic notebooks, electronic books, in-vehicle information devices, mobile radios, mobile TVs, mobile printers, mobile scanners, mobile modems and other portable electronic devices, as well as mechanical watches and pocketbooks. Clocks, flashlights, hand mirrors, etc. may be included. Examples of the members constituting the portable electronic device may include an optical film or a display panel used for an image display device such as a thin layer display such as a liquid crystal display or a film type display. The reinforcing film disclosed herein can also be preferably used in a mode of being attached to various members in automobiles, home appliances and the like.

Further, since the reinforcing film disclosed herein has bending recovery and bending holding force, it is possible to take advantage of its features to bendable elements (for example, flexible devices such as flexible displays, rollable devices and foldable devices). It can also be preferably used in a manner of being attached to a member constituting a device provided with). Examples of such a device include the above-mentioned various portable devices (portable devices). Examples of the members constituting the portable electronic device may include an optical film, a display panel, or the like used in an image display device such as a liquid crystal display or an organic EL (electroluminescence) display. The reinforcing film disclosed herein is preferable for reinforcing applications of members constituting the device (typically, an image display device referred to as a flexible device or a foldable device) in such a portable electronic device. Can be used.

Further, the reinforcing film disclosed herein reinforces the optical member used as a component of, for example, a liquid crystal display panel, a plasma display panel (PDP), an organic EL display, etc., at the time of manufacturing, transporting, or the like. Suitable for applications. It is useful as a reinforcing film applied to optical members such as polarizing plates (polarizing films) for liquid crystal display panels, wave plates, retardation plates, optical compensation films, brightness improving films, light diffusing sheets, and reflective sheets.

The use of the reinforcing film disclosed herein is not particularly limited, and can be used for various purposes such as imparting rigidity and impact resistance. The reinforcing film disclosed herein can be preferably used not only for flexible device applications as described above, but also for other applications that do not include flexible devices. The fact that the reinforcing film has bending recovery and bending holding force means that the range of application of the reinforcing film is not limited, and this has a great practical advantage.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified.

[Synthesis of polymer (A)]
(Synthesis Example A1)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a cooler, 90.2 parts of 2-ethylhexyl acrylate (2EHA), 8.6 parts of 4-hydroxybutyl acrylate (4HBA), N. -Acryloylmorpholine (ACMO) 1.2 parts, 2,2'-azobisisobutyronitrile (AIBN) 0.2 parts as a polymerization initiator, and ethyl acetate as a polymerization solvent are charged, and nitrogen gas is gently stirred. Was introduced, and the polymerization reaction was carried out for 6 hours while keeping the liquid temperature in the flask at around 65 ° C. to prepare an acrylic polymer A1 solution having a polymer concentration of 35%. The weight average molecular weight (Mw) of the acrylic polymer A1 was 540,000.

(Synthesis Example A2)
Solution polymerization in the same manner as in Synthesis Example A1 except that the monomer composition was changed to 2EHA / 4HBA / ACMO / butyl acrylate (BA) = 86.1 parts / 9.7 parts / 1.8 parts / 2.4 parts. A solution of the acrylic polymer A2 was obtained.

(Synthesis Example A3)
A solution of the acrylic polymer A3 was obtained by performing solution polymerization in the same manner as in Synthesis Example A1 except that the monomer composition was changed to BA / 4HBA = 96 parts / 4 parts.

(Synthesis Example A4)
Other than changing the monomer composition to 2EHA / 2-hydroxyethyl acrylate (HEA) / methyl methacrylate (MMA) / N-vinyl-2-pyrrolidone (NVP) = 65 parts / 15 parts / 7 parts / 13 parts A solution of the acrylic polymer A4 was obtained by performing solution polymerization in the same manner as in Synthesis Example A1.

[Synthesis of polymer (B)]
(Synthesis Example B1)
101.15 parts of ethyl acetate, 40 parts of MMA, 20 parts of n-butyl methacrylate (nBMA), 20 parts of 2-ethylhexyl methacrylate (2EHMA), and a polyorganosiloxane skeleton-containing methacrylate monomer having a functional group equivalent of 900 g / mol (trade name: X). -22-174ASX, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 8.7 parts, polyorganosiloxane skeleton-containing methacrylate monomer having a functional group equivalent of 4600 g / mol (trade name: KF-2012, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 11.3 parts, And 0.8 part of thioglycerol as a chain transfer agent was put into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, a cooler and a dropping funnel. Then, after stirring at 70 ° C. under a nitrogen atmosphere for 30 minutes, 0.2 part of AIBN was added as a thermal polymerization initiator and reacted at 70 ° C. for 3 hours. Subsequently, after stirring at 80 ° C. for 30 minutes, 0.1 part of AIBN was further added and reacted at 80 ° C. for 2 hours. Then, 0.05 part of AIBN was further added and reacted at 80 ° C. for 2 hours to obtain polymer B1. The Mw of the obtained polymer B1 was 20000, and the Tg ( _TB ) was -13.8 ° C.

(Synthesis Examples B2 to B6)
Polymers B2 to B6 were prepared in the same manner as in the preparation of polymer B1, except that the composition of the monomer components was changed as shown in Table 1. The Tg ( _TB ) of each polymer is -8.4 ° C for polymer B2, -7.2 ° C for polymer B3, -0.6 ° C for polymer B4, -25.1 ° C for polymer B5, and 9 for polymer B6. It was 0.4 ° C. In Table 1, MMA is methyl methacrylate (Tg 105 ° C.), nBMA is n-butyl methacrylate (Tg 20 ° C.), 2EHMA is 2-ethylhexyl methacrylate (Tg-10 ° C.), and iBMA is isobutyl methacrylate (Tg 48 ° C.). CHMA is cyclohexyl methacrylate (Tg66 ° C.), X-22-174ASX is a polyorganosiloxane skeleton-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by Shin-Etsu Chemical Co., Ltd., functional group equivalent 900 g / mol), KF- 2012 represents a polyorganosiloxane skeleton-containing methacrylate monomer (trade name: KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd., functional group equivalent of 4600 g / mol).

The composition of the monomer components used in the preparation of the polymers B1 to B6 and the Tg ( _TB ) of the polymers B1 to B6 are summarized in Table 1.

The Mw of each of the above-mentioned polymers was measured under the following conditions using a GPC device (manufactured by Tosoh Corporation, HLC-8220GPC), and was determined by polystyrene conversion.
[GPC conditions]
-Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)
-Sample injection volume: 10 μL
・ Eluent: THF ・ Flow rate: 0.6 mL / min
・ Measurement temperature: 40 ° C
·column:
Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
-Detector: Differential refractometer (RI)

[Making a reinforcing film]
<Example 1>
Add 100 parts of acrylic polymer A1, 2.0 parts of polymer B1, and 0.10 part of isocyanate compound C1 (trade name "Coronate HX", manufactured by Tosoh Corporation) as a cross-linking agent in terms of solid content, and add 0.10 part of the total solid content. Was diluted with ethyl acetate so as to have a concentration of 30% to obtain an acrylic pressure-sensitive adhesive solution according to this example.
A release liner (trade name "Diafoil MRF75", manufactured by Mitsubishi Chemical Corporation) made of a polyester resin having a thickness of 75 μm and having a silicone treatment on one side was prepared, and the acrylic pressure-sensitive adhesive solution obtained above was prepared on the silicone-treated surface. Was applied and dried at 130 ° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of 25 μm.
Next, a polyimide base material having a thickness of 50 μm (trade name “UPIREX 50S”, manufactured by Ube Industries, Ltd.) was bonded to the surface of the obtained pressure-sensitive adhesive layer to obtain a reinforcing film according to this example. This reinforcing film has an adhesive layer on one side of a base material, and has the form of an adhesive sheet with a release liner in which the release surface of the release liner is in contact with the adhesive surface.
The molar ratio ([NCO]) of the reinforcing film of this example is based on the amount of OH (the number of moles of hydroxyl groups in the acrylic polymer A1) and the amount of NCO (the number of moles of isocyanate groups of the isocyanate compound) in the pressure-sensitive adhesive layer. / [OH]) was calculated and found to be 0.008.

<Examples 2 to 3>
The acrylic pressure-sensitive adhesive solution according to each example was obtained in the same manner as in Example 1 except that the polymer B2 (Example 2) and the polymer B3 (Example 3) were used instead of the polymer B1. A reinforcing film according to each example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that each of these acrylic pressure-sensitive adhesive solutions was used.

<Examples 4 to 7>
As shown in Table 2, the amount of the isocyanate compound C1 used was 0.015 parts (Example 4), 0.05 parts (Example 5), 0. The acrylic pressure-sensitive adhesive solution according to each example was obtained in the same manner as in Example 1 except that the parts were changed to 20 parts (Example 6) and 0.60 parts (Example 7). A reinforcing film according to each example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that each of these acrylic pressure-sensitive adhesive solutions was used.

<Examples 8 to 10>
As shown in Table 2, the amount of the polymer B1 used is 1.0 part (Example 8), 3.0 parts (Example 9), and 6.0 parts (Example) with respect to 100 parts of the acrylic polymer A1. An acrylic pressure-sensitive adhesive solution according to each example was obtained in the same manner as in Example 1 except that it was changed to 10). A reinforcing film according to each example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that each of these acrylic pressure-sensitive adhesive solutions was used.

<Example 11>
An acrylic pressure-sensitive adhesive solution according to this example was obtained in the same manner as in Example 1 except that the acrylic polymer A2 was used instead of the acrylic polymer A1. The reinforcing film according to this example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Example 12>
Acrylic polymer A3 is used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Kagaku Co., Ltd.) is used as a cross-linking agent in terms of solid content for 100 parts of acrylic polymer A3. An acrylic pressure-sensitive adhesive solution according to this example was obtained in the same manner as in Example 1 except that 0.07 part was used. The reinforcing film according to this example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Example 13>
As shown in Table 2, the amount of the isocyanate compound C2 used was changed to 0.09 part in terms of solid content with respect to 100 parts of the acrylic polymer A3, and the same as in Example 12, the acrylic according to this example. A system adhesive solution was obtained. The reinforcing film according to this example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Comparative Examples 1 and 2>
The acrylic pressure-sensitive adhesive solution according to each example was obtained in the same manner as in Example 1 except that the polymer B5 (Comparative Example 1) and the polymer B6 (Comparative Example 2) were used instead of the polymer B1. A reinforcing film according to each example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that each of these acrylic pressure-sensitive adhesive solutions was used.

<Comparative Example 3>
Acrylic polymer A4 is used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Kagaku Co., Ltd.) is used as a cross-linking agent in terms of solid content for 100 parts of acrylic polymer A4. An acrylic pressure-sensitive adhesive solution according to this example was obtained in the same manner as in Example 1 except that 0.50 part was used. The reinforcing film according to this example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Comparative Examples 4 to 5>
As shown in Table 2, the amount of the isocyanate compound C2 used was changed to 1.10 parts (Comparative Example 4) and 2.50 parts (Comparative Example 5) in terms of solid content with respect to 100 parts of the acrylic polymer A4. Other than that, the acrylic pressure-sensitive adhesive solution according to each example was obtained in the same manner as in Comparative Example 3. A reinforcing film according to each example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that each of these acrylic pressure-sensitive adhesive solutions was used.

<Example 14>
An acrylic pressure-sensitive adhesive solution according to this example was obtained in the same manner as in Example 1 except that the polymer B4 was used instead of the polymer B1. The reinforcing film according to this example was produced in the same manner as in the production of the reinforcing film according to Example 1 except that the obtained acrylic pressure-sensitive adhesive solution was used.

<Evaluation>
[Surface elastic modulus]
The reinforcing film according to each example was aged at 50 ° C. for 1 day, and the surface elastic modulus was measured. The release liner that protects the adhesive surface is peeled off, and an indenter is pressed into the surface of the adhesive layer to a pressing depth of 6 μm using a nanoindenter device (Triboindenter manufactured by Hysitron Inc.), and the maximum load is measured by the above nanoindenter. (Pmax) [GPa / mm ² ] was obtained. This is the formula:
Surface hardness [GPa] = Pmax / A
The surface hardness was calculated and converted into [kPa] units, and recorded as the surface elastic modulus at 23 ° C. (23 ° C. surface elastic modulus). The measurement conditions are as follows. In the above equation, A is the contact projection area [mm ² ] of the indenter.
(Measurement condition)
Indenter approach speed: 5 μm / s
Maximum displacement: 6 μm
Pushing speed: 5 μm / s
Pulling speed: 5 μm / s
Indenter used: Conical (spherical indenter: radius of curvature 10 μm)
Measurement method: Single push measurement Measurement temperature: Room temperature (23 ° C)

[Bulk modulus G'and tan δ]
A release liner R1 (trade name "Diafoil MRF75", manufactured by Mitsubishi Chemical Corporation) made of a 75 μm thick polyester resin with a silicone treatment on one side was prepared, and the acrylic pressure-sensitive adhesive according to each example was prepared on the silicone-treated surface. The solution was applied and dried at 130 ° C. for 1 minute to form a 25 μm-thick pressure-sensitive adhesive layer. Next, on the surface of the obtained pressure-sensitive adhesive layer, a release liner R2 (trade name "Diafoil MRE75", manufactured by Mitsubishi Chemical Corporation) made of a polyester resin having a thickness of 75 μm, which was treated with silicone on one side, was applied to the silicone-treated surface. Was coated so as to be on the pressure-sensitive adhesive layer side, and aged at 50 ° C. for 1 day.
Only the obtained pressure-sensitive adhesive layer was taken out and laminated to a thickness of about 1 mm, which was punched to φ8 mm to prepare a columnar pellet, which was used as a measurement sample.
The above measurement sample is fixed to a jig of a φ8 mm parallel plate, and a dynamic elastic modulus (“ARES” manufactured by TA Instruments) is used to store elastic modulus G ′ and loss elastic modulus G under the following conditions. ″ And the loss positive tan δ were measured and the storage modulus G'23 [kPa] at ₂₃ ° C, the storage modulus G'80 [kPa] at ₈₀ ° C and the tan δ at 80 ° C (loss modulus at 80 ° C). The storage elastic modulus _G'80 ) at G " _80/80 ° C. was determined.
-Measurement mode: Shear mode-Temperature range: -70 ° C to 200 ° C
・ Temperature rise rate: 5 ° C / min
・ Frequency: 1Hz
The storage elastic modulus G'corresponds to a portion stored as elastic energy when the material is deformed, and is an index indicating the degree of hardness. The loss elastic modulus G ″ corresponds to the loss energy portion dissipated by internal friction or the like when the material is deformed, and represents the degree of viscosity.

[Initial adhesive strength]
The reinforcing film according to each example was aged at 50 ° C. for 1 day, and the release liner was cut into a width of 25 mm and a length of 140 mm as a measurement sample. The release liner was peeled off from the measurement sample to expose the adhesive surface, and a 2 kg hand roller was reciprocated once on a stainless steel plate (SUS304BA plate) as an adherend and crimped. The measurement sample crimped to the adherend in this way was left at an ambient temperature of 23 ° C. for 30 minutes, and then a tensile tester (manufactured by Shimadzu Corporation, trade name "Autograph AG-Xplus HS 6000 mm / min high-speed model"). (AG-50NX plus) ”), the load when the reinforcing film is peeled from the adherend is measured and measured under the conditions of a peeling angle of 180 degrees and a peeling speed (tensile speed) of 300 mm / min. The average load at the time was recorded as the initial adhesive force [gf / 25 mm].

[Adhesive strength after heating]
For the reinforcing film according to each example, a measurement sample was prepared and pressure-bonded to the adherend in the same manner as in the initial adhesive strength measurement. Then, the measurement sample pressure-bonded to the adherend was heated at an environmental temperature of 60 ° C. for 60 minutes. After that, it was left at an ambient temperature of 23 ° C. for 30 minutes, and a tensile tester (manufactured by Shimadzu Corporation, trade name "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)") was used. Under the conditions of a peeling angle of 180 degrees and a peeling speed (tensile speed) of 300 mm / min, the load when the reinforcing film is peeled from the adherend is measured, and the average load at the time of measurement is measured as the adhesive force after heating [gf / 25 mm. ] Recorded as.

[Bending retention test]
The reinforcing film according to each example was aged at 50 ° C. for 1 day, then the release liner was peeled off, and a 25 μm-thick polyimide substrate (trade name “UPIREX 25S”, Ube Industries, Ltd.) was applied to the exposed adhesive surface. Was bonded and heated at 60 ° C. for 60 minutes to bring them into close contact. Next, the obtained measurement sample (laminated body) was fixed in a bent state so as to have a diameter of 6 mm with the 25 μm substrate side as the inside, and heated at 80 ° C. for 15 hours. Then, after leaving it at room temperature (23 ° C.) and confirming that it had cooled sufficiently, the measurement sample was unfixed in the bent state, and was bent using a protractor within 10 minutes after the unfixing. The bending angle [°] of the above measurement sample was measured to evaluate the bending recovery. The bending angle is the opening angle of the measurement sample (the angle on the side where the measurement sample opens from the bent state). The closer it is to 180 °, the better the bending recovery property, and the closer the bending angle is to 0 °. Flexibility is inferior.
Subsequently, as an evaluation of the bending holding force, the presence or absence of "peeling" at the bent portion of the measurement sample was visually confirmed, and when "peeling" was not observed, it was evaluated as "○", and "peeling" was observed. Was evaluated as "x".

Table 2 shows the evaluation results for the reinforcing films according to Examples 1 to 13 and Comparative Examples 1 to 5. Table 2 also shows an outline of the composition of the pressure-sensitive adhesive layer according to each example.

Further, the evaluation results of the bending recovery property and the recovery holding power of the reinforcing film according to Example 14 are shown in Table 3 together with the outline of Example 14 (composition and characteristics of the pressure-sensitive adhesive layer).

As shown in Table 2, the pressure-sensitive adhesives according to Examples 1 to 13 contain a polymer (A) and a polymer (B), and the Tg of the polymer (B) is −20 ° C. to 5 ° C. It was within range. The reinforcing films according to these examples have lower initial adhesive strength and increased adhesive strength after heating as compared with Comparative Examples 1 and 2 in which the Tg of the polymer (B) was outside the range of −20 ° C. to 5 ° C. It was a better match. Further, in the reinforcing films according to Examples 1 to 13, the elastic modulus at 23 ° C. of the pressure-sensitive adhesive layer was in the range of 1 to 20 kPa, and the bending recovery property and the bending holding force were good. On the other hand, in Comparative Examples 3 to 5 in which the surface elastic modulus at 23 ° C. was outside the range of 1 to 20 kPa, peeling was observed in the bending retention test.

More specifically, from the comparison of Examples 1 to 3, the higher the Tg of the polymer (B) in the range of −20 ° C. to 5 ° C., the lower the initial adhesive strength while realizing the increase in the adhesive strength after heating. , The initial light peelability tended to be improved. On the other hand, in Comparative Example 1 in which the Tg of the polymer (B) was less than −20 ° C., the initial adhesive strength was high and the light peelability was inferior. Further, in Comparative Example 2 in which the Tg of the polymer (B) was more than 5 ° C., the amount of increase in the adhesive strength after heating was small. Further, from the comparison of Examples 4 to 7, it was found that the higher the elastic modulus at 23 ° C. of the pressure-sensitive adhesive layer was in the range of 1 to 20 kPa, the more the bending recovery tended to be improved, and the initial adhesive strength and the adhesive strength after heating were found to be higher. It tended to be lower. Examples 5 to 7 are superior in bending recovery to Example 4, have a surface elastic modulus at 23 ° C. of 2 kPa or more, and have a tan δ ₈₀ at 80 ° C. in the range of 0.10 to 0.60. rice field. Further, in Example 7, both the surface elastic modulus and the bulk elastic modulus were high, and the increase in adhesive strength after heating was relatively low as compared with Examples 4 to 6. Further, in Examples 4 to 6, no difference in the bulk elastic modulus G'23 at ₂₃ ° C. of the pressure-sensitive adhesive layer was observed. Moreover, the ₈₀ ° C. bulk elastic modulus G'80 in Examples 1 to 3 and 5 was the same. It can be said that the 23 ° C. surface elastic modulus had a higher correlation with the bending recovery property than the bulk elastic modulus with respect to Examples 1 to 7. In addition, in Examples 1 to 7, the isocyanate group and the hydroxyl group in the pressure-sensitive adhesive layer of Examples 1 to 3, 5 to 6 in which the initial adhesive force, the adhesive force after heating, the bending recovery property and the bending holding force were improved in a more balanced manner. The molar ratio with and ([NCO] / [OH]) was in the range of 0.002 to 0.03.

Further, from the comparison of Examples 8 to 10, it was confirmed that the adhesive strength tends to decrease as the amount of the polymer (B) used increases. In Examples 8 to 9, where the amount of the polymer (B) used was in the range of 0.5 to 5 parts with respect to 100 parts of the polymer (A), the initial adhesive strength was less than 400 gf / 25 mm and the adhesive after heating was adhered. The force was 500 gf / 25 mm or more, and the light peelability at the initial stage of pasting and the increase in adhesive force after heating were better compatible. Further, as the amount of the polymer (B) used increased, the surface elastic modulus at 23 ° C. tended to increase, and the bending recovery property tended to decrease. Further, from the results of Examples 11 to 13, it was confirmed that the desired effect was achieved even if the type of the pressure-sensitive adhesive polymer (A) and the type of the cross-linking agent were changed.

Further, as shown in Table 3, also in Example 14 using the polymer (B) in which the 23 ° C. surface elastic modulus of the pressure-sensitive adhesive layer is in the range of 1 to 20 kPa and the Tg is −1.6 ° C. It was confirmed that both bending recovery and bending holding force were compatible. Although not particularly shown in the table, the reinforcing film according to Example 14 has an initial adhesive force of less than 400 gf / 25 mm (specifically, less than 200 gf / 25 mm), and an amount of increase in the adhesive force after heating (adhesive force). The increase ratio N ₆₀ / N ₂₃ ) was 7 (fold), which realized the effect of the technique disclosed here.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

1, 2, 3 Reinforcing film 10 Supporting base material 10A 1st surface 10B 2nd surface 21 Adhesive layer (1st adhesive layer)
21A Adhesive surface (first adhesive surface)
21B adhesive surface (second adhesive surface)
22 Adhesive layer (second adhesive layer)
22A Adhesive surface (second adhesive surface)
31,32

Release liner

100, 200, 300 Reinforcing film with release liner

Claims

A reinforcing film with an adhesive layer,
The pressure-sensitive adhesive layer contains a polymer (A) and a polymer (B).
The polymer (B) contains a monomer unit having a polyorganosiloxane skeleton and a (meth) acrylic monomer unit.
The pressure-sensitive adhesive layer has a surface elastic modulus of 1 to 20 kPa at 23 ° C.
A reinforcing film having a glass transition temperature TB of the polymer ( B ) of −20 ° C. to 5 ° C.
The pressure-sensitive adhesive layer has a bulk elastic modulus G'23 at 23 ° C. of 10 to 200 kPa, a bulk elastic modulus G'80 at 80 ° C. of 5 to 100 kPa, and a tan δ 80 at 80 ° C. of 0. The reinforcing film according to claim 1, which is 10 to 0.60.
The reinforcing film according to claim 1 or 2, wherein the polymer (A) is an acrylic polymer.
The content of the polymer (B) in the pressure-sensitive adhesive layer is 0.5 to 5 parts by weight with respect to 100 parts by weight of the polymer (A), according to any one of claims 1 to 3. Reinforcing film.
The reinforcing material according to any one of claims 1 to 4, wherein the molar ratio ([NCO] / [OH]) of the isocyanate group and the hydroxyl group contained in the pressure-sensitive adhesive layer is 0.002 to 0.03. the film.
An optical member to which the reinforcing film according to any one of claims 1 to 5 is attached.
An electronic member to which the reinforcing film according to any one of claims 1 to 5 is attached.