TW202344394A - Laminate body and manufacturing method of the same characterized in that the laminate body is excellent in appearance and can contribute to the improvement of productivity - Google Patents

Abstract

The present invention provides a laminated body that is excellent in appearance and can contribute to the improvement of productivity. The laminate body of the embodiment of the present invention is sequentially provided with a protective film, a functional film and an adhesive layer. Furthermore, the protective film is provided with a first protective film and a second protective film, which are adhesive, sequentially from the side provided with the functional film. The first protective film is laminated to the second protective film via adhesive.

Description

Laminated body and method of manufacturing the laminated body

The present invention relates to a laminated body and a method for manufacturing the laminated body.

Functional membranes sometimes use adhesives to adhere to the adherend. For example, image display panels mounted on image display devices represented by liquid crystal display devices and electroluminescence (EL) display devices (such as organic EL display devices and inorganic EL display devices) are usually bonded using adhesives. There are functional films such as polarizing plates and retardation films (for example, see Patent Document 1).

In order to layer a functional film on a volume to be adhered, an adhesive layer may be laminated on the functional film in advance. It is desired to perform the lamination well and obtain a laminated body having excellent appearance. In addition, it is also desirable that the obtained laminate is in a state in which it can be laminated well with other films. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2021-103286

[Problem to be solved by the invention]

In view of the above-mentioned circumstances, the main object of this invention is to provide the laminated body which is excellent in appearance and can contribute to productivity improvement. [Technical means to solve problems]

The laminated body according to the embodiment of the present invention has a protective film, a functional film, and an adhesive layer in this order, and the protective film includes a first protective film and a second protective film having adhesiveness in order from the side where the functional film is arranged. film, the above-mentioned first protective film and the above-mentioned second protective film are laminated via an adhesive. In one embodiment, the peeling force of the protective film from the functional film is 0.03 N/25mm or less. In one embodiment, the surface roughness Ra of the second protective film is 0.1 μm or less. In one embodiment, the storage elastic modulus of the adhesive layer at 25°C is above 0.14 MPa. In one embodiment, the adhesive composition constituting the adhesive layer includes a (meth)acrylic polymer and an isocyanate cross-linking agent, and the isocyanate cross-linking agent is smaller than the (meth)acrylic polymer. The content is 1.5 parts by weight or more per 100 parts by weight. In one embodiment, the functional film is a retardation film. A method of manufacturing a polarizing plate with a retardation layer according to another embodiment of the present invention includes: peeling the protective film from the laminated body, and then laminating the laminated body and the polarizing plate.

A method of manufacturing a laminated body according to another embodiment of the present invention includes: laminating a protective film on the first main surface of a functional film having first main surfaces and second main surfaces facing each other; and attaching a protective film to the functional film. The above-mentioned second main area of the film is layered with a coating layer of an adhesive composition, and the above-mentioned coating layer is aged to obtain an adhesive layer; and the above-mentioned protective film sequentially includes the adhesive composition from the side where the above-mentioned functional film is arranged. The first protective film and the second protective film are laminated via an adhesive. In one embodiment, the above-mentioned manufacturing method includes: forming a coating layer of the above-mentioned adhesive composition on a release liner. In one embodiment, the above-mentioned manufacturing method includes: rolling the long functional film into a roll in a state where the above-mentioned protective film is attached and the above-mentioned coating layer is laminated; and rolling into a roll. The above-mentioned aging is performed in the cylindrical state. In one embodiment, the above-mentioned coating layer is formed by applying the above-mentioned adhesive composition and drying, and the above-mentioned drying temperature is 130°C or lower. In one embodiment, the above-mentioned aging is performed until the storage elastic modulus at 25°C reaches above 0.14 MPa. In one embodiment, the peeling force of the protective film from the functional film is 0.03 N/25mm or less. In one embodiment, the surface roughness Ra of the second protective film is 0.1 μm or less. In one embodiment, the adhesive composition includes a (meth)acrylic polymer and an isocyanate cross-linking agent, and the content of the isocyanate cross-linking agent is 100 parts by weight of the (meth)acrylic polymer. It is 1.5 parts by weight or more. [Effects of the invention]

According to the embodiment of the present invention, it is possible to provide a laminated body that has excellent appearance and contributes to improvement in productivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiment, but this is only an example and does not limit the interpretation of the present invention.

(Definition of terms and symbols) The definitions of terms and symbols in this manual are as follows. (1)Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index in the plane reaches the maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), " nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550 nm at 23°C. When the thickness of the layer (film) is d (nm), Re (λ) is obtained according to the formula: Re (λ) = (nx-ny) × d. (3) Phase difference in thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. When the thickness of the layer (film) is d (nm), Rth (λ) is obtained according to the formula: Rth (λ) = (nx-nz) × d. (4)Nz coefficient The Nz coefficient is found based on Nz=Rth/Re. (5)Angle When angles are mentioned in this specification, the angles include both clockwise and counterclockwise angles relative to the reference direction. So, for example, "45°" means ±45°.

A method of manufacturing a laminated body according to one embodiment of the present invention includes: laminating a protective film on the first main surface of a functional film having first main surfaces and second main surfaces facing each other (step 1); and The second main area of the adhesive film is layered with a coating layer of the adhesive composition (step 2), and the coating layer is aged to obtain an adhesive layer.

FIG. 1 is a schematic cross-sectional view showing the schematic structure of a laminated body according to one embodiment of the present invention. FIGS. 2A and 2B are diagrams illustrating the steps of a method for manufacturing a laminated body according to one embodiment of the present invention. As shown in FIG. 1 , the laminated body 52 has the protective film 20 , the functional film 10 , the adhesive layer 32 and the release liner 40 in this order.

In step 1, the protective film 20 is bonded to the first principal surface 10a of the functional film 10 having the first principal surface 10a and the second principal surface 10b facing each other. FIG. 2A shows the state after the bonding is completed. . Typically, the functional film 10 and the protective film 20 are formed into long strips, and are bonded together while being transported by a roller (so-called roll-to-roll type). Here, "elongated shape" refers to an elongated shape with a length that is sufficiently long relative to the width. For example, it refers to an elongated shape with a length that is 10 times or more, preferably 20 times or more, with respect to the width. By using the protective film 20, the transportability of the functional film 10 can be ensured.

The functional film 10 can be used as a retardation film, for example. In this case, the functional film 10 may be a stretched film of a resin film (stretched resin film). Typically, the resin film contains a resin having at least one bond group selected from the group consisting of a carbonate bond and an ester bond. In other words, the resin film contains polycarbonate-based resin, polyester-based resin, or polyestercarbonate-based resin.

The retardation film may have any appropriate optical characteristics depending on the use and the like. In one embodiment, the retardation film functions as a λ/4 plate. Typically, the refractive index characteristics show the relationship of nx>ny=nz. The in-plane phase difference Re(550) of the retardation film is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and further preferably 120 nm to 160 nm. Furthermore, "ny=nz" here includes not only the case where ny and nz are completely equal, but also the case where ny and nz are substantially equal. Therefore, within the range that does not impair the effect of the present invention, ny>nz or ny<nz may be satisfied.

The Nz coefficient of the retardation film is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. The retardation film can also exhibit inverse wavelength dispersion characteristics in which the phase difference value becomes larger in accordance with the wavelength of the measurement light. In this case, Re(450)/Re(550) of the retardation film is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less.

The thickness of the retardation film is preferably not less than 10 μm and not more than 70 μm, more preferably not less than 20 μm and not more than 60 μm.

The protective film 20 includes a first protective film 21 and a second protective film 22 in order from the side where the functional film 10 is arranged. As shown in the figure, the second protective film 22 is laminated on the first protective film 21 via the adhesive layer 23 . The thickness of the protective film 20 is, for example, 40 μm to 120 μm. Regarding the lamination of the protective film 20 , the second protective film 22 can be laminated on the first protective film 21 after the functional film 10 is laminated on the first protective film 21 , or the second protective film 22 can be laminating on the first protective film 21 in advance. After protecting the film 22, it is bonded to the functional film 10. The second protective film 22 is preferably bonded to the first protective film 21 by using a surface protective film obtained by forming an adhesive layer 23 on the second protective film 22 in advance.

As the first protective film 21, a self-adhesive film having adhesiveness is used. As a self-adhesive film, a polyolefin film is typically used. Specifically, the self-adhesive film preferably contains polyethylene, polypropylene, or a mixture thereof. Here, polyethylene includes homopolymers of ethylene and copolymers of ethylene and other olefins. Polypropylene includes homopolymers of propylene and copolymers of propylene and other olefins.

Specific examples of the polyethylene include high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (L-LDPE).

Examples of the other olefins include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, and decene. Among them, ethylene, propylene, and butylene are preferably used. In the production of copolymers of ethylene or propylene and other olefins, the blending ratio of other olefins is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of the total of ethylene or propylene and other olefins. Preferably, it is 20 parts by weight or less.

In one embodiment, the polyolefin film preferably contains polyethylene. Specifically, the polyolefin film is preferably a polyethylene film or a mixture film of polyethylene and polypropylene. When the polyolefin film contains a mixture of polyethylene and polypropylene, the content ratio of polyethylene is preferably 60 to 97 parts by weight, more preferably 70 parts by weight based on 100 parts by weight of the total of polyethylene and polypropylene. parts by weight or more, and more preferably 80 parts by weight or more.

Self-adhesive films (polyolefin films) can contain particles, pigments, colorants, antistatic agents, ultraviolet absorbers, antioxidants, heat stabilizers, chlorine capture agents and other ingredients.

The self-adhesive film (polyolefin film) can be a single layer with a uniform composition, or it can have a laminated structure of two or more layers with different compositions. Specific examples of the laminated structure include a two-layer structure in which the first layer and the second layer are composed of different components, and a three-layer structure in which the first layer, the second layer, and the third layer are composed of different layers. Furthermore, the compositions of the first layer and the third layer may be substantially the same or different. Moreover, the self-adhesive film (polyolefin film) may be an unstretched film or a stretched film, and it is preferably an unstretched film.

The surface roughness Ra of the self-adhesive film (Ra of the main surface opposite to the adhesive surface) is, for example, 0.05 μm or more and 0.5 μm or less. The thickness of the self-adhesive film is preferably 15 μm to 60 μm, more preferably 20 μm to 50 μm, and further preferably 25 μm to 40 μm.

Examples of materials for forming the second protective film 22 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), etc. Polyester polymers; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate polymers; (meth)acrylic polymers such as polymethyl methacrylate; polynorcamphenyl cycloolefin polymers such as olefins. These may be used alone or in combination of two or more.

As the adhesive layer 23, any suitable structure can be adopted. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. agent. By adjusting the type, quantity, combination and blending ratio of the monomers that form the base resin of the adhesive, as well as the blending amount of the cross-linking agent, reaction temperature, reaction time, etc., an adhesive with the required characteristics corresponding to the target can be prepared . The base resin of the adhesive can be used alone or in combination of two or more. The base resin is preferably an acrylic resin (specifically, the adhesive layer preferably contains an acrylic adhesive). The thickness of the adhesive layer is, for example, 5 μm to 15 μm.

The surface roughness Ra of the second protective film 22 is preferably 0.1 μm or less, more preferably 0.07 μm or less, and further preferably 0.05 μm or less. The thickness of the second protective film 22 is preferably 20 μm to 80 μm, more preferably 20 μm to 60 μm, and further preferably 30 μm to 50 μm.

The peeling force of the protective film 20 to the functional film 10 (essentially the peeling force of the first protective film 21 to the functional film 10) is preferably 0.03 N/25mm or less, more preferably 0.025 N/25mm or less. Such peeling force enables, for example, good lamination with other films described below. Specifically, the protective film 20 has excellent peelability when peeled off from the functional film 10 and can be well laminated with other films. On the other hand, the peeling force of the protective film 20 from the functional film 10 is preferably 0.01 N/25mm or more.

In step 2, the coating layer 30 of the adhesive composition is laminated on the second main surface 10b of the functional film 10. FIG. 2B shows the state after the laminated body precursor 50 is completed. In the illustrated example, the release liner 40 is used to laminate the coating layer 30 of the adhesive composition on the second main surface 10 b of the functional film 10 . Specifically, the laminate precursor 50 is produced by forming the coating layer 30 of the adhesive composition on the release liner 40 and laminating the release liner 40 on which the coating layer 30 is formed on the functional film 10 . By using the release liner 40, for example, the functional film 10 can be wound into a roll while protecting the coating layer 30.

The coating layer 30 can be formed by applying an adhesive composition and drying it. Typically, the adhesive composition is an acrylic adhesive. Typically, acrylic adhesives include (meth)acrylic polymers.

The (meth)acrylic polymer preferably contains alkyl (meth)acrylate as a monomer component. In addition, (meth)acrylate refers to acrylate and/or methacrylate.

Examples of the alkyl group contained in the alkyl (meth)acrylate include a linear or branched alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl group include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl Base, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl. These may be used alone or in combination. The average carbon number of the alkyl group is preferably 3 to 10.

The content of the alkyl (meth)acrylate in the (meth)acrylic polymer is preferably 50 to 95 parts by weight relative to 100 parts by weight of the monomers forming the (meth)acrylic polymer. It is 70 parts by weight to 90 parts by weight.

The (meth)acrylic polymer may contain a monomer having a polar functional group as a monomer component. Examples of the monomer having a polar functional group include a carboxyl group-containing monomer and a hydroxyl group-containing monomer. These may be used alone or in combination. It is preferred to use monomers containing carboxyl groups.

The above-mentioned carboxyl group-containing monosystem has a carboxyl group and a compound having polymerizable unsaturated double bonds such as (meth)acrylyl group and vinyl group. Specific examples of the carboxyl group-containing monomer include: (meth)acrylic acid, (meth)acrylic acid carboxyethyl ester, (meth)acrylic acid carboxypentyl ester, itaconic acid, maleic acid, fumaric acid, Crotonic acid. Among them, acrylic is preferably used.

The content of the monomer with polar functional groups in the above-mentioned (meth)acrylic polymer may be 1 to 10 parts by weight relative to 100 parts by weight of the monomers forming the (meth)acrylic polymer, or it may be It is 2.5 parts by weight to 8 parts by weight.

The (meth)acrylic polymer may contain a monomer having an aromatic ring as a monomer component. As the monomer having an aromatic ring, benzyl acrylate is preferably used.

The content of the monomer having an aromatic ring in the (meth)acrylic polymer may be 5 to 30 parts by weight relative to 100 parts by weight of the monomers forming the (meth)acrylic polymer, or may be 10 parts by weight to 20 parts by weight.

The weight average molecular weight Mw of the (meth)acrylic polymer is, for example, 100×10 ⁴ to 300×10 ⁴ , preferably 150×10 ⁴ to 250×10 ⁴ .

The above-mentioned acrylic adhesive may contain a cross-linking agent. Typically, the cross-linking agent is included in the acrylic adhesive in the form after cross-linking reaction in the obtained adhesive layer. By containing a cross-linking agent, for example, appropriate cohesive force can be imparted to an acrylic adhesive. As the cross-linking agent, it is preferable to use an isocyanate-based cross-linking agent (especially a trifunctional isocyanate-based cross-linking agent). The compounding amount of the isocyanate cross-linking agent is preferably 1.5 to 10 parts by weight, more preferably 2 to 5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

In one embodiment, the acrylic adhesive substantially contains no peroxide cross-linking agent. According to this method, for example, the obtained adhesive layer can be suppressed from whitening and the deterioration of the adhesive properties can be prevented.

The above-mentioned acrylic adhesive may also contain any suitable additives. Representative examples of additives include various silane coupling agents.

The drying temperature is preferably 130°C or lower, may be 120°C or lower, may be 110°C or lower, or may be 100°C or lower. By drying at such a temperature, the cross-linking speed of the adhesive composition can be suppressed to suppress the whitening, and an adhesive layer satisfying the storage elastic modulus described below can be obtained. On the other hand, the drying temperature is, for example, 90°C or higher. The drying time is, for example, 60 seconds to 120 seconds.

The gel fraction of the coating layer 30 (immediately after forming the coating layer) is, for example, 5% or more and less than 85%, or it may be 50% or less, or it may be 20% or less. The thickness of the coating layer 30 (thickness of the obtained adhesive layer) is, for example, 10 μm to 50 μm.

Release liner 40 may be composed of any suitable plastic film. Specific examples of the plastic film include polyethylene terephthalate (PET) film, polyethylene film, and polypropylene film. As the release liner 40, it is preferable to use a plastic film whose surface is coated with a release agent. Specific examples of the release agent include silicone release agents, fluorine release agents, and long-chain alkyl acrylate release agents.

The thickness of the release liner 40 is, for example, 30 μm or more, preferably 40 μm or more, more preferably 45 μm or more, and further preferably 50 μm or more. On the other hand, the thickness of the release liner 40 is, for example, 100 μm or less, preferably 80 μm or less.

The formed coating layer 30 is aged to obtain the laminated body 52 shown in FIG. 1 . When the functional film 10 (laminate precursor 50 ) is wound into a roll after the coating layer 30 is formed, the coating layer 30 is aged while being wound into a roll. The aging temperature is, for example, 20°C to 40°C. The aging time is preferably more than 24 hours, preferably 2 to 7 days. By aging, the following storage elastic modulus can be well achieved.

In the laminated body precursor 50 wound into a roll shape, depending on the surface state (concave-convex shape of the surface) of the protective film 20 located inside the coating layer 30, concavities may occur in the coating layer 30 during aging. marks, and there are dents in the obtained adhesive layer. The adhesive layer obtained by aging the coating layer 30 may adhere to the image display panel body of the image display panel. Therefore, dents in the adhesive layer may adversely affect the image display characteristics. FIG. 3 is a partially enlarged view of a wound body of a laminated body precursor schematically showing an example of the occurrence of dents. In the coating layer 30 located outside the convex portion 20a, dents may be generated imitating the convex portion 20a existing on the surface of the protective film 20 located inside. When the coating layer 30 is not sufficiently aged, dents tend to easily occur. When the protective film 20 (second protective film 22) satisfies the above-mentioned surface roughness Ra, the occurrence of dents in the coating layer 30 can be suppressed, thereby obtaining an adhesive layer in which the occurrence of dents (paste dents) is suppressed.

The gel fraction (gel fraction after aging) of the obtained adhesive layer is preferably 85% or more, more preferably 90% or more. The storage elastic modulus of the adhesive layer at 25°C is preferably above 0.14 MPa, more preferably above 0.16 MPa. On the other hand, the storage elastic modulus of the adhesive layer at 25°C is preferably 1.5 MPa or less.

The laminated body according to the embodiment of the present invention can be used by being laminated on a polarizing plate, for example. Specifically, a functional film can be used as a retardation film and laminated on a polarizing plate to obtain a polarizing plate with a retardation layer. 4 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer can be obtained by peeling off the protective film 20 and peeling off the functional film (retardation film) 10 and the adhesive layer 32 obtained by aging the coating layer 30 The laminated body 52 of the spacer 40 and the polarizing plate 60 are laminated. Typically, the laminated body 52 and the polarizing plate 60 are formed into a long strip, and lamination is performed while conveying them by rollers (so-called roll-to-roll type). Typically, the polarizing plate 100 with the retardation layer is attached to the image display panel body of the image display panel through the adhesive layer 32 . By satisfying the above-mentioned storage elastic modulus of the adhesive layer 32 , it is possible to suppress deterioration of display characteristics due to environmental changes. For example, it is possible to suppress changes in the phase difference characteristics of the functional film (retardation film) 10 .

In the illustrated example, the polarizing plate 60 has a polarizing element 61, a first protective layer 62 disposed on one side of the polarizing element 61, and a second protective layer 63 disposed on the other side of the polarizing element 61. However, the second protective layer 63 can be omitted.

Each of the above components can be laminated via any suitable adhesive layer. Specific examples of the adhesive layer include an adhesive layer and an adhesive layer. For example, the polarizing element and the protective layer are bonded together via an adhesive layer. Specifically, the polarizing element and the protective layer are bonded together using an active energy ray-curable adhesive. The thickness of the active energy ray curable adhesive after curing (the thickness of the adhesive layer) is, for example, 0.2 μm to 3.0 μm, preferably 0.4 μm to 2.0 μm, and more preferably 0.6 μm to 1.5 μm. Furthermore, for example, the polarizing plate and the functional film are bonded together via an adhesive layer. The thickness of the adhesive layer disposed between the polarizing plate and the functional film is, for example, 10 μm to 20 μm.

[Polarizing element] Typically, the polarizing element is a resin film containing a dichroic substance (eg, iodine). Examples of the resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films.

The thickness of the polarizing element is preferably 18 μm or less, more preferably 15 μm or less, further preferably 12 μm or less. On the other hand, the thickness of the polarizing element is preferably 1 μm or more.

The polarizing element preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single transmittance of the polarizing element is, for example, 41.5% to 46.0%, preferably 42.0% to 46.0%, and more preferably 44.5% to 46.0%. The polarization degree of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and further preferably 99.9% or more.

The polarizing element can be produced by any suitable method. Specifically, the polarizing element can be made of a single-layer resin film or a laminate of two or more layers.

Typically, the method of producing a polarizing element from the above-mentioned single-layer resin film includes subjecting the resin film to dyeing treatment using dichroic substances such as iodine or dichroic dye and stretching treatment. As the resin film, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films are used. This method may further include: insolubilization treatment, swelling treatment, cross-linking treatment, etc. This manufacturing method is well known and commonly used in the industry, so detailed description is omitted.

The polarizing element obtained using the above-mentioned laminated body can be produced using, for example, a laminated body of a resin base material and a resin film or a resin layer (typically, a PVA-based resin layer). Specifically, it can be produced by applying a PVA-based resin solution to a resin base material and drying it to form a PVA-based resin layer on the resin base material, thereby obtaining a laminate of the resin base material and the PVA-based resin layer. body; and stretching and dyeing the laminated body to make the PVA-based resin layer into a polarizing element. In this embodiment, it is preferable to form a PVA-based resin layer containing a halide compound and a PVA-based resin on one side of the resin base material. Typically, stretching includes immersing the laminate in a boric acid aqueous solution and stretching. Furthermore, if necessary, the stretching may further include stretching the laminate in the air at a high temperature (for example, 95° C. or higher) before stretching in a boric acid aqueous solution. Furthermore, in this embodiment, it is preferable to subject the laminated body to a drying and shrinking process in which the laminated body is heated while being transported in the longitudinal direction, thereby shrinking the laminated body by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process on the laminate. By introducing auxiliary stretching, even when PVA is coated on thermoplastic resin, the crystallinity of PVA can be improved to achieve higher optical properties. In addition, by improving the alignment of PVA in advance at the same time, when immersed in water in the subsequent dyeing process or stretching process, problems such as decrease in alignment and dissolution of PVA can be prevented, thereby achieving higher optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared with the case where the PVA-based resin layer does not contain a halide, the alignment disorder of the PVA molecules and the decrease in alignment can be suppressed, thereby achieving higher optics. characteristic. Furthermore, by shrinking the laminate in the width direction through drying shrinkage treatment, higher optical properties can be achieved. A polarizing plate can be obtained by laminating a protective layer on the peeling surface obtained by peeling the resin base material from the obtained laminate of the resin base material/polarizing element or on the surface opposite to the peeling surface. Details of the manufacturing method of such a polarizing element are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated into this specification by reference.

[protective layer] The above-mentioned protective layer can be formed of any suitable film that can be used as a protective layer of the polarizing element. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, Polyimide series, polyether series, polystyrene series, polystyrene series, polynorbornene and other cyclic olefin series, polyolefin series, (meth)acrylic series, acetate series and other resins.

Typically, the polarizing plate with the retardation layer is disposed on the viewing side of the image display device (eg, organic EL display device), and the first protective layer 62 is disposed on the viewing side. Therefore, the first protective layer 62 may also be subjected to surface treatments such as hard coating (HC) treatment, anti-reflection treatment, anti-adhesion treatment, and anti-glare treatment if necessary.

The thickness of the protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and further preferably 15 μm to 35 μm. Furthermore, when the above-mentioned surface treatment is performed, the thickness of the first protective layer 62 is the thickness including the thickness of the surface treatment layer.

In one embodiment, the second protective layer 63 disposed between the polarizing element 61 and the functional film 10 is preferably optically isotropic. In this specification, the so-called "optical isotropy" means that the in-plane phase difference Re (550) is 0 nm to 10 nm, and the phase difference Rth (550) in the thickness direction is -10 nm to +10 nm. The thickness of the second protective layer 63 disposed between the polarizing element 61 and the functional film 10 is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and further preferably 10 μm to 30 μm. [Example]

Hereinafter, the present invention will be specifically described through examples, but the present invention is not limited by these examples. In addition, the thickness, surface roughness Ra, gel fraction, and storage elastic modulus are values measured by the following measurement methods. In addition, unless otherwise clearly stated, "parts" and "%" in the examples and comparative examples are based on weight. ＜Thickness＞ The thickness of 10 μm or less is measured using a scanning electron microscope (manufactured by JEOL Ltd., product name "JSM-7100F"). Thickness exceeding 10 μm is measured using a digital micrometer (manufactured by ANRITSU, product name "KC-351C"). ＜Surface roughness Ra＞ The arithmetic mean surface roughness Ra (μm) was measured in accordance with JIS B 0601 (1994 edition). Specifically, the measurement object was bonded to a glass plate (MICRO SLIDE GLASS, product number S, manufactured by MATSUNAMI Co., Ltd., thickness 1.3 mm, 45 mm × 50 mm) using an adhesive to prepare a measurement sample. Next, a stylus-type surface roughness measuring instrument (manufactured by Kosaka Laboratory Co., Ltd., high-precision fine shape measuring instrument, trade name "Surfcorder ET4000") having a measuring needle with a curvature radius R of 2 μm at the tip (diamond) was used. ), using the conditions of scanning speed 1 mm/second, critical value 0.8 mm, and measurement length 12 mm, measure the uneven shape of the outermost surface of the obtained measurement sample in a fixed direction. Based on this measurement, the arithmetic mean surface roughness Ra is calculated. Furthermore, the above-mentioned high-precision fine shape measuring device automatically calculates the measurement value. ＜Gel fraction＞ The gel fraction was measured immediately after applying the adhesive composition, 3 days after application, and 5 days after application. Specifically, after measuring the weight of a 5 cm × 5 cm test piece cut out from the laminate of the release liner and the coating layer, the test piece was immersed in 50 g of toluene for 1 hour. After immersion, the residue was taken out, dried at 150° C. for 10 minutes, the weight was measured again, and the gel fraction (%) was calculated. ＜Storage elastic modulus G'(25)＞ By dynamic viscoelasticity measurement, the storage elastic modulus G' was measured at a temperature of 25°C. Specifically, a dynamic viscoelasticity measuring device (manufactured by TA Instruments, "ARES-G2") was used to measure under the following conditions. As a sample for measurement, a sample obtained by changing the adhesive layer to be evaluated to a thickness of 1 mm was used. ． Transformation mode: twist ． Measuring frequency: 1 Hz ． Heating rate: 5℃/min ． Shape: Parallel plates, 8.0 mmϕ

[Example 1] (Preparation of retardation film) A stretched resin film (manufactured by Teijin Co., Ltd., "PURE-ACE RM-147") with a thickness of 52 μm was prepared as a retardation film.

(Laying of protective film) A polyethylene film (manufactured by TORAY ADVANCED FILM Co., Ltd., "TORETEC (registered trademark) 7832C") is bonded to one side of the retardation film. Thickness: 30 μm. Ra of the main surface opposite to the bonding surface: 0.05 μm). Then, a surface protective film (manufactured by Nitto Denko Co., Ltd., "E-MASK RP301", thickness 60 m) was bonded to the surface of the polyethylene film. Furthermore, the surface protective film is a film obtained by forming an adhesive layer (thickness 10 μm) on a PET film with a thickness of 50 μm.

(Preparation of adhesive composition A) To a four-necked flask equipped with a stirring wing, a thermometer, a nitrogen introduction tube and a cooler, add 79.9 parts by weight of n-butyl acrylate (BA), 15.0 parts by weight of benzyl acrylate (BzA), 5.0 parts by weight of acrylic acid (AA) and acrylic acid 4-Hydroxybutyl ester (HBA) 0.1. Then, to 100 parts by weight of the mixture of BA, AA and HBA, add 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and stir slowly while introducing nitrogen to the flask. After replacing the flask with nitrogen, the liquid temperature in the flask was maintained at approximately 55°C, and the polymerization reaction was carried out for 7 hours. Next, ethyl acetate was added to the obtained reaction liquid to adjust the solid content concentration to 12% by weight, thereby obtaining a solution of the (meth)acrylic polymer (A). The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) is 2.2 million.

To 100 parts by weight of the solid content of the obtained (meth)acrylic polymer (A), a trimethylolpropane/toluene diisocyanate trimer adduct (isocyanate cross-linking agent, manufactured by TOSOH Co., Ltd.) was mixed. "CORONATE L") 3 parts by weight and 3-glycidoxypropyltriethoxysilane (silane coupling agent, manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM403") 0.1 parts by weight, to obtain a solvent-based adhesive composition A .

(Formation of coating layer) The adhesive composition obtained was coated on the treated surface of a 38 μm-thick PET-based film (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., "MRF38") that was polysiloxane-treated on one side using a jet coater. A. Dry in an air-circulating constant-temperature oven at 95°C for 100 seconds to form a coating layer with a thickness of 15 μm and a gel fraction of 8%.

(Production of laminated body) A release liner on which the coating layer is formed is bonded to the side of the retardation film where the protective film is not bonded, thereby obtaining a laminated body precursor. The obtained laminate precursor was rolled into a roll shape with a release liner arranged inside, and left in this state at 23° C. for 5 days to age the coating layer. In this way, a laminate having an adhesive layer with a storage elastic modulus of 0.18 MPa and a gel fraction of 94% or more was obtained.

[Example 2] During the formation of the coating layer, the drying temperature was set to 125°C. Except for this, the same operation was performed as in Example 1 to obtain an adhesive layer with a storage elastic modulus of 0.18 MPa and a gel fraction of 94% or more. The layered body.

[Comparative example 1] In the lamination of the protective film, the surface protective film was not used (only the polyethylene film was bonded to the retardation film). In addition, the same operation was performed as in Example 1 to obtain a film with a storage elastic modulus of 0.18 MPa and A laminate of an adhesive layer with a gel fraction of 94% or more.

[Comparative example 2] In the lamination of the protective film, the polyethylene film was not used (only the surface protective film was bonded to the retardation film). The same operation was performed as in Example 1 to obtain a film with a storage elastic modulus of 0.18 MPa and A laminate of an adhesive layer with a gel fraction of 94% or more.

[Comparative example 3] Except that the protective film was not bonded to the retardation film, the same operation was performed as in Example 1 to obtain a laminate having an adhesive layer with a storage elastic modulus of 0.18 MPa and a gel fraction of 94% or more.

[Reference example] In the formation of the coating layer, the following adhesive composition B was used, and except that it was dried at 155°C for 60 seconds after coating, the same operation was performed as in Comparative Example 1 to obtain a storage elastic modulus of A laminate of an adhesive layer with a gel fraction of 0.18 MPa and over 94%.

<Adhesive composition B> To 100 parts by weight of the solid content of the (meth)acrylic polymer (A), a trimethylolpropane/toluene diisocyanate trimer adduct (isocyanate cross-linking agent, manufactured by TOSOH Co., Ltd., "CORONATE L") 3 parts by weight of benzyl peroxide (peroxide cross-linking agent, manufactured by Nippon Oils and Fats Co., Ltd., "NYPER BMT-K40") 0.1 parts by weight and 3-glycidoxypropyltriethoxysilane ( Silane coupling agent, manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM403") 0.1 part by weight, to obtain a solvent-based adhesive composition B.

Regarding the Examples and Comparative Examples, the following evaluations were performed. The evaluation results are summarized in Table 1 together with various measured values. In addition, the surface roughness Ra shown in Table 1 is a value obtained by measuring the member located on the outermost surface of the laminated body (the side opposite to the release liner). ＜Evaluation＞ 1.Transportability The transportability until the laminated body was obtained (when the coating layer was bonded to the retardation film) was evaluated. [Evaluation criteria] Good: no bending or breakage caused by transportation Defect: Bending and breaking caused by transportation 2. Peelability Using a universal tensile testing machine, a sample cut into a size of 50 mm in width and 100 mm in length from the obtained laminated body was peeled off in the length direction at a peeling speed of 300 mm/min and a peeling angle of 90°. The time was measured. Peeling force (N/25mm). Specifically, the peeling force of the protective film to the retardation film was measured. In addition, the measurement was performed in an environment of 23°C and 50%RH. Furthermore, a sample cut out from the obtained laminate into a size of 70 mm in width and 100 mm in length was peeled off in the length direction at a peeling speed of 30 mm/min and a peeling angle of 90° using a universal tensile testing machine. A surface potentiometer (manufactured by Kasuga Electric Co., Ltd., "KSD-0103") was fixed at a position 100 mm above the center of the sample in a plan view to measure the potential (kV) generated at the surface of the retardation film immediately after peeling off. The measurement was performed in an environment of 23°C and 50%RH. 3. Appearance (dents) Evaluation is made by visually observing the appearance of the laminated body (after aging) and confirming the number of dents found within a range of 1 m in the longitudinal direction of the laminated body.

Table 1 ​ Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3 Reference example protective film Overall thickness (μm) 90 90 30 60 - 30 First thickness (μm) 30 30 30 - - 30 Second thickness (μm) 60 60 - 60 - - coating layer Gel fraction immediately after coating (%) 8 8 8 8 8 60 Gel fraction after 3 days (%) 94 94 94 94 94 94 adhesive layer Store elastic modulus 0.18 0.18 0.18 0.18 0.18 0.18 Surface roughness Ra(μm) 0.05 0.05 0.25 0.05 0.003 0.25 Transportability good good good good bad good Peeling force(N/25mm) 0.023 0.023 0.022 0.070 - 0.022 Potential (kV) 2.1 2.1 2.0 5.0 - 2.0 Dent(piece/m) 7 7 270 7 - 7

It can be seen that in the examples, excellent releasability and appearance were achieved. In the reference example, whitening of the adhesive layer, which is thought to be caused by aggregation of the cross-linking agent, was confirmed, but in the examples and comparative examples, whitening of the adhesive layer was not confirmed. [Industrial availability]

The laminated body according to the embodiment of the present invention can be used, for example, to manufacture a polarizing plate with a retardation layer used in an image display device. Representative examples of the image display device include a liquid crystal display device, an organic EL display device, and an inorganic EL display device.

10:Functional membrane 10a: First main surface 10b: Second main side 20:Protective film 20a:convex part 21:The first protective film 22:Second protective film 23: Adhesive layer 30: Coating layer 32:Adhesive layer 40:Release liner 50: Laminated body precursor 52:Laminated body 60:Polarizing plate 61:Polarizing element 62: First protective layer 63:Second protective layer 100: Polarizing plate with phase difference layer

FIG. 1 is a schematic cross-sectional view showing the schematic structure of a laminated body according to one embodiment of the present invention. FIG. 2A is a diagram showing the manufacturing process 1 of the laminated body according to one embodiment of the present invention. FIG. 2B is a diagram showing step 2 following step 1 described above. FIG. 3 is a partially enlarged view of a wound body of a laminated body precursor schematically showing an example of the occurrence of dents. 4 is a schematic cross-sectional view showing the schematic structure of a polarizing plate with a retardation layer according to one embodiment of the present invention.

10:Functional membrane

20:Protective film

21:The first protective film

22:Second protective film

23: Adhesive layer

32: Adhesive layer

40:Release liner

52:Laminated body

Claims (15)

A laminated body having a protective film, a functional film and an adhesive layer in this order, and The protective film includes a first protective film and a second protective film having adhesiveness in order from the side where the functional film is arranged, and the first protective film and the second protective film are laminated via an adhesive. The laminate according to claim 1, wherein the peeling force of the protective film from the functional film is 0.03 N/25mm or less. The laminate according to claim 1, wherein the second protective film has a surface roughness Ra of 0.1 μm or less. The laminated body of claim 1, wherein the storage elastic modulus of the adhesive layer at 25°C is 0.14 MPa or more. The laminate according to claim 1, wherein the adhesive composition constituting the adhesive layer includes a (meth)acrylic polymer and an isocyanate cross-linking agent, and the isocyanate cross-linking agent is smaller than the (meth)acrylic acid. The content of the polymer is more than 1.5 parts by weight per 100 parts by weight. The laminated body of claim 1, wherein the functional film is a retardation film. A method for manufacturing a laminated body, which includes: Laminating a protective film on the first main surface of the functional film having first main surfaces and second main surfaces facing each other; and Layer a coating layer of the adhesive composition on the second main area of the functional film, and age the coating layer to obtain an adhesive layer; and The protective film includes a first protective film and a second protective film having adhesiveness in order from the side where the functional film is arranged, and the first protective film and the second protective film are laminated via an adhesive. The manufacturing method of claim 7 includes: forming a coating layer of the adhesive composition on a release liner. The manufacturing method of Claim 7, which includes: winding the long strip of functional film into a roll in a state where the protective film is attached and the coating layer is laminated; and The above-mentioned aging is performed while being wound into a roll shape. The manufacturing method of claim 7, wherein the coating layer is formed by applying the adhesive composition and drying, and the drying temperature is 130°C or lower. The manufacturing method of Claim 7, wherein the above-mentioned aging is performed until the storage elastic modulus at 25°C reaches 0.14 MPa or above. The manufacturing method of claim 7, wherein the peeling force of the protective film to the functional film is 0.03 N/25mm or less. The manufacturing method of claim 7, wherein the surface roughness Ra of the second protective film is 0.1 μm or less. The manufacturing method of claim 7, wherein the adhesive composition includes a (meth)acrylic polymer and an isocyanate cross-linking agent, and the isocyanate cross-linking agent is based on 100 weight of the (meth)acrylic polymer. The content is 1.5 parts by weight or more. A method of manufacturing a polarizing plate with a retardation layer, which includes: peeling off the protective film from the laminated body according to claim 6, and then laminating the laminated body and the polarizing plate.