WO2022034885A1

WO2022034885A1 - Adhesive sheet, adhesive sheet with release sheet, multilayer body, and method for producing multilayer body

Info

Publication number: WO2022034885A1
Application number: PCT/JP2021/029558
Authority: WO
Inventors: 直人安田; 睦之加嶋; 雅樹西田
Original assignee: 王子ホールディングス株式会社
Priority date: 2020-08-11
Filing date: 2021-08-10
Publication date: 2022-02-17

Abstract

The present invention provides: an adhesive sheet which has high adhesive power and excellent blister resistance; an adhesive sheet with a release sheet, and a multilayer body, each of which comprises this adhesive sheet; and a method for producing a multilayer body.　An adhesive sheet which is provided with an adhesive layer that contains a semi-cured product of an adhesive composition, wherein: the adhesive composition contains a crosslinkable acrylic copolymer (A), a crosslinking agent (B), a polyfunctional monomer (C) that has two or more polymerizable double bonds in each molecule, and a photopolymerization initiator (D); from 5% by mass to 15% by mass is contained relative to all constituent units in the crosslinkable acrylic copolymer (A); and from 1 part by mass to 20 parts by mass of the polyfunctional monomer (C) is contained per 100 parts by mass of the crosslinkable acrylic copolymer (A).

Description

Adhesive sheet, adhesive sheet with release sheet, laminated body and method for manufacturing the laminated body

The present invention relates to an adhesive sheet, an adhesive sheet with a release sheet, a laminate, and a method for manufacturing the laminate.

Conventionally, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with display devices have been widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for bonding optical members, and transparent adhesive sheets are also used for bonding display devices and input devices. ..

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive sheet for an optical member is produced by a known polymerization method. Examples of this polymerization method include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like. Among them, since it is easy to produce and an optically transparent pressure-sensitive adhesive sheet can be produced, a solvent is used for the pressure-sensitive adhesive layer. Adhesive sheets using mold adhesives are widely used. Examples of the solvent-based pressure-sensitive adhesive include those containing acrylic resin as a main component. Such an acrylic resin is obtained by carrying out a polymerization reaction in a solvent in which an acrylic monomer is dissolved in a solvent by a method called solution polymerization. In solution polymerization, the molecular weight of the polymer increases as the polymerization progresses, and the viscosity of the reaction solution increases. There is. Therefore, in order to secure the cohesive force required for the pressure-sensitive adhesive, a cross-linking agent capable of reacting with an acrylic resin such as an isocyanate-based compound or an epoxy-based compound is blended in the pressure-sensitive adhesive composition. Such a cross-linking agent reacts with the acrylic resin over time to construct a cross-linking network and enhance the cohesive force of the pressure-sensitive adhesive layer.

Further, as a method for forming an adhesive sheet for an optical member, a method of curing by two-stage curing in which cross-linking by heat (or active energy ray) and then polymerization by active energy ray (or heat) is performed may be used. be. Since such a pressure-sensitive adhesive sheet is formed from, for example, a pressure-sensitive adhesive composition having both thermosetting property and active energy ray-curing property (hereinafter, also referred to as "dual-curing type pressure-sensitive adhesive composition"), the pressure-sensitive adhesive sheet is thermosetting. And has active energy ray curability. Therefore, it is possible to develop a hardness that is easy to handle by performing only thermosetting, for example, before bonding to the adherend, and then after bonding to the adherend, further active energy is obtained. By curing with a wire (called post-curing or after-cure), it can be firmly adhered to the adherend.

For example, in Patent Document 1, in a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state, the pressure-sensitive adhesive composition is a cross-linking acrylic polymer, a cross-linking agent, and a reactive double bond in the molecule. There has been proposed a pressure-sensitive adhesive sheet containing a polyfunctional monomer and a photopolymerization initiator having two or more of the above, and having a predetermined probe tack value or the like when the pressure-sensitive adhesive layer is post-cured. Such an adhesive sheet is excellent in processability and high temperature and high humidity durability.

Japanese Unexamined Patent Publication No. 2020-7407

However, in recent years, with the increase in screen size and performance of display devices and the like, the required performance for adhesive sheets has further increased. In particular, a pressure-sensitive adhesive sheet in which the curing shrinkage of the pressure-sensitive adhesive layer in a post-cured state is further suppressed and has excellent adhesion and durability even under high temperature and high humidity, that is, a pressure-sensitive adhesive sheet with further improved blister resistance is strong. It is desired. In this respect, in the adhesive sheet, the adhesiveness (adhesive strength) and the blister resistance tend to be in a trade-off relationship with each other, so that it is difficult to further improve the performance of both.

The present invention has been made in view of the above, and provides a pressure-sensitive adhesive sheet having high adhesive strength and excellent blister resistance, a pressure-sensitive adhesive sheet and a laminate containing the pressure-sensitive adhesive sheet, and a method for manufacturing the laminate. The purpose is.

As a result of diligent research to achieve the above object, the present inventors have found that the above object can be achieved by composing the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer with a specific component. The invention was completed.

That is, the present invention includes, for example, the subjects described in the following sections.
Item 1
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition comprises a crosslinkable acrylic copolymer (A), a crosslinker (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and photopolymerization. The crosslinkable acrylic copolymer (A) containing the initiator (D) contains a structural unit (a2) having an acidic functional group, and the content ratio of the structural unit (a2) is the crosslinkable property. It is 5 to 15% by mass with respect to all the constituent units contained in the acrylic copolymer (A).
The crosslinkable acrylic copolymer (A) has a glass transition temperature of −40 to −20 ° C.
A pressure-sensitive adhesive sheet containing 1 to 20 parts by mass of the polyfunctional monomer (C) per 100 mass of the crosslinkable acrylic copolymer (A).
Item 2
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition comprises a crosslinkable acrylic copolymer (A), a crosslinker (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and photopolymerization. The crosslinkable acrylic copolymer (A) contains an initiator (D), and the crosslinkable acrylic copolymer (A) contains a non-crosslinkable (meth) acrylic acid ester unit (a1) and a structural unit (a2) having an acidic functional group. It is a copolymer and
The non-crosslinkable (meth) acrylic acid ester unit (a1) includes a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and an alkyl group having 3 or more carbon atoms (meth). Contains acrylic acid alkyl esters,
The content ratio of the structural unit (a2) is 5 to 15% by mass with respect to all the structural units contained in the crosslinkable acrylic copolymer (A).
A pressure-sensitive adhesive sheet containing 1 to 20 parts by mass of the polyfunctional monomer (C) per 100 mass of the crosslinkable acrylic copolymer (A).
Item 3
The gel fraction of the pressure-sensitive adhesive layer is 50 to 80%, and
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light amount is 3000 mJ / cm ² , and then cured, and the gel fraction is 75 to 90%.
Item 4
The adhesive strength of the pressure-sensitive adhesive layer is 5 N / 25 mm or more, and the pressure-sensitive adhesive layer is 5 N / 25 mm or more.
Item 2. The item according to any one of Items 1 to 3, wherein the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light amount is 3000 mJ / cm ² , and the adhesive force is 10 N / 25 mm or more when the pressure-sensitive adhesive layer is post-cured. Adhesive sheet.
Item 5
A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different peeling forces on both sides of the pressure-sensitive adhesive sheet according to any one of Items 1 to 4.
Item 6
The adhesive sheet according to any one of Items 1 to 4 and an adherend provided on at least one surface side of the adhesive sheet are provided.
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is a laminated body in a post-cured state.
Item 7
Item 6. The laminate according to Item 6, wherein the adherend is at least one selected from the group consisting of a resin plate and a resin film.
Item 8
Step 1 of laminating the adherend on at least one surface side of the pressure-sensitive adhesive sheet according to any one of Items 1 to 4, and
A method for producing a laminated body, comprising the step 2 of post-curing the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays.
Item 9
Item 8. The method for manufacturing a laminated body according to Item 8, further comprising a step of processing the laminated body after the step 2.
Item 10
Item 6. The method for producing a laminate according to Item 7 or 8, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 150 μm.

The adhesive sheet according to the present invention has high adhesive strength and excellent blister resistance. Therefore, the pressure-sensitive adhesive sheet according to the present invention is less likely to float or peel off from the adherend even in a high-temperature and high-humidity environment, and is excellent in adhesion and durability.

It is the schematic which shows the cross section of the adhesive sheet of this invention which has a release sheet or a base material. It is a schematic diagram which shows the cross section of an example of the laminated body of this invention. It is a schematic diagram which shows the cross section of another example of the laminated body of this invention.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, the expression "contains" and "contains" includes the concepts of "contains", "contains", "substantially consists" and "consists only".

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments and specific examples, but the present invention is not limited to such embodiments. In addition, the numerical range represented by using "-" in this specification means the range including the numerical values before and after "-" as the lower limit value and the upper limit value.

In the present specification, "(meth) acrylate" represents both acrylate and methacrylate, or either, and "(meth) acrylic acid" represents both acrylic acid and methacrylic acid, or either.

Further, in the present specification, "monomer" and "monomer" are synonymous, and "polymer" and "polymer" are synonymous.

1. 1. Adhesive Sheet As one embodiment of the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive sheet A described later can be mentioned, and as another embodiment, the pressure-sensitive adhesive sheet B can be mentioned. The pressure-sensitive adhesive sheet A includes a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition. In the pressure-sensitive adhesive sheet A, the pressure-sensitive adhesive composition comprises a cross-linking acrylic copolymer (A), a cross-linking agent (B), and a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule. ) And the photopolymerization initiator (D). In the pressure-sensitive adhesive sheet A, the crosslinkable acrylic copolymer (A) contains a structural unit (a2) having an acidic functional group, and the content ratio of the structural unit (a2) is the crosslinkable acrylic copolymer (a2). It is 5 to 15% by mass with respect to all the structural units contained in A), the glass transition temperature of the crosslinkable acrylic copolymer (A) is −40 to −20 ° C., and the polyfunctional monomer (the polyfunctional monomer (A)). C) is contained in an amount of 1 to 20 parts by mass per 100 mass of the crosslinkable acrylic copolymer (A).

The pressure-sensitive adhesive sheet B includes a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition. In the pressure-sensitive adhesive sheet B, the pressure-sensitive adhesive composition comprises a cross-linking acrylic copolymer (A), a cross-linking agent (B), and a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule. ) And the photopolymerization initiator (D). In the pressure-sensitive adhesive sheet B, the crosslinkable acrylic copolymer (A) is a copolymer containing a non-crosslinkable (meth) acrylic acid ester unit (a1) and a structural unit (a2) having an acidic functional group. The non-crosslinkable (meth) acrylic acid ester unit (a1) is a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms, and an alkyl group having 3 or more carbon atoms (meth). ) The acrylic acid alkyl ester is contained, and the content ratio of the structural unit (a2) is 5 to 15% by mass with respect to all the structural units contained in the crosslinkable acrylic copolymer (A), and the polyfunctional simple substance is used. The weight (C) is contained in an amount of 1 to 20 parts by mass per 100 mass of the crosslinkable acrylic copolymer (A).

Since the pressure-sensitive adhesive sheet according to the present invention includes a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition, it has high adhesive strength and excellent blister resistance. Conventionally, from the viewpoint of weight reduction and improvement of impact resistance, resin plates such as polycarbonate and polymethyl methacrylate may be used in applications such as display devices, but when these resin plates are used, high temperature and high temperature are used. A blister phenomenon in which foaming or floating occurs in the pressure-sensitive adhesive layer in a moist environment is likely to occur, that is, there is a problem in blister resistance. However, the adhesive sheet according to the present invention is less likely to cause the blister phenomenon than the conventional one, is less likely to float or peel off from the adherend even in a high temperature and high humidity environment, and is excellent in adhesion and durability.

Hereinafter, the adhesive sheet A and the adhesive sheet B are collectively referred to as "adhesive sheet" or "adhesive sheet of the present invention". The pressure-sensitive adhesive composition contained in the pressure-sensitive adhesive sheet is a raw material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, and is particularly the dual-curable pressure-sensitive adhesive composition. As described above, the pressure-sensitive adhesive composition is a polyfunctional single having at least a crosslinkable acrylic copolymer (A), a crosslinker (B), and two or more polymerizable double bonds in the molecule as constituent components. It contains a weight (C) and a photopolymerization initiator (D).

(Crosslinkable acrylic copolymer (A))
The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet A is a polymer containing at least a (meth) acrylic-based structural unit and a structural unit (a2) having an acidic functional group, and has a glass transition temperature. It is a polymer in the range of −40 ° C. or higher and −20 ° C. or lower. In the present specification, the "unit" or "constituent unit" in the (meth) acrylic structural unit is a repeating unit (also referred to as a monomer unit) constituting the polymer.

Examples of the (meth) acrylic constituent unit include one type or two or more different non-crosslinkable (meth) acrylic acid ester units (a1). Therefore, the crosslinkable acrylic copolymer (A) includes one or more non-crosslinkable (meth) acrylic acid ester units (a1) and a structural unit (a2) having an acidic functional group. Examples include copolymers.

The non-crosslinkable (meth) acrylic acid ester unit (a1) is a repeating unit derived from the (meth) acrylic acid alkyl ester. The (meth) acrylic acid alkyl ester is a (meth) acrylic acid alkyl ester in which the alkyl group has 2 or less carbon atoms in the alkyl ester, and a (meth) acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms. It is preferable to include both. In this case, in the crosslinkable acrylic copolymer (A), the glass transition temperature tends to be in the above range, and the cohesive force of the polymer component tends to increase even after the pressure-sensitive adhesive layer is post-cured. The blister resistance of the adhesive sheet is likely to improve.

Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 2 or less carbon atoms include methyl (meth) acrylate and ethyl (meth) acrylate. One of these may be used alone, or two or more thereof may be used in combination. The (meth) acrylic acid alkyl ester having an alkyl group having 2 or less carbon atoms is preferably methyl (meth) acrylate and / or ethyl (meth) acrylate.

Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms include (meth) propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. T-butyl (meth) acrylic acid, n-pentyl (meth) acrylic acid, n-hexyl (meth) acrylic acid, 2-ethylhexyl (meth) acrylic acid, n-octyl (meth) acrylic acid, (meth) acrylic acid Isooctyl, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n- (meth) acrylate Examples thereof include dodecyl, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate. One of these may be used alone, or two or more thereof may be used in combination.

In a (meth) acrylic acid alkyl ester having 3 or more carbon atoms of an alkyl group, the number of carbon atoms of the alkyl group is preferably 4 or more, and the number of carbon atoms of the alkyl group is preferably 18 or less, 12 It is more preferably less than or equal to, and more preferably 8 or less.

The (meth) acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms is selected from n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate because the adhesiveness of the pressure-sensitive adhesive sheet tends to be high. It is preferable to contain at least one of these.

The (meth) acrylic acid alkyl ester unit is a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and a (meth) acrylic acid alkyl ester unit having an alkyl group having 3 or more carbon atoms. When both are included, the cohesive force of the polymer component is likely to increase even after the pressure-sensitive adhesive layer is post-cured, foaming is likely to be suppressed, and the blister resistance performance of the pressure-sensitive adhesive sheet is likely to be improved. The content ratio can be as follows. That is, with respect to the total mass of the (meth) acrylic acid alkyl ester unit having 2 or less carbon atoms in the alkyl group and the (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms in the alkyl group, the alkyl group The (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms is preferably 40% by mass or more, more preferably 45% by mass or more, further preferably 50% by mass or more, and 54% by mass. % Or more is particularly preferable, 95% by mass or less is preferable, 90% by mass or less is more preferable, and 85% by mass or less is further preferably 80% by mass or less. Is particularly preferable.

The non-crosslinkable (meth) acrylic acid ester unit (a1) includes a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and a (meth) acrylic acid having an alkyl group having 3 or more carbon atoms. It can contain (meth) acrylic acid ester units other than acid alkyl ester units. Alternatively, the non-crosslinkable (meth) acrylic acid ester unit (a1) is a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms, and an alkyl group having 3 or more carbon atoms (meth). ) It may consist of only an acrylic acid alkyl ester unit.

As a reminder, the non-crosslinkable (meth) acrylic acid ester unit (a1) is a structural unit other than the structural unit (a2) having an acidic functional group described later, that is, an acidic functional unit. A structural unit having no group, particularly a structural unit having no carboxy group.

In the (meth) acrylic acid alkyl ester, the alkyl group may be either linear or branched.

On the other hand, the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet B is a polymer formed of (meth) acrylic constituent units, and is at least a non-crosslinkable (meth) acrylic acid ester unit (a1). It is a copolymer containing and a structural unit (a2) having an acidic functional group. Here, the non-crosslinkable (meth) acrylic acid ester unit (a1) is a repeating unit derived from the (meth) acrylic acid alkyl ester, and the alkyl group has 2 or less carbon atoms (meth) acrylic acid alkyl. It contains an ester unit and a (meth) acrylic acid alkyl ester unit having an alkyl group having 3 or more carbon atoms. The (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and the (meth) acrylic acid alkyl ester unit having an alkyl group having 3 or more carbon atoms have a crosslinkable acrylic co-weight in the pressure-sensitive adhesive sheet A. This is the same as the (meth) acrylic acid alkyl ester unit in which the alkyl group contained in the coalescence (A) has 2 or less carbon atoms and the (meth) acrylic acid alkyl ester unit in which the alkyl group has 3 or more carbon atoms. Hereinafter, the (meth) acrylic acid alkyl ester unit in the pressure-sensitive adhesive sheet B will be described just in case.

The (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms is a repeating unit derived from a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group. The alkyl group referred to here indicates an alkyl group at the alkyl ester moiety of the (meth) acrylic acid alkyl ester, and may be either linear or branched.

The (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms in the alkyl group is a repeating unit derived from the (meth) acrylic acid alkyl ester having 3 or less carbon atoms in the alkyl group. The alkyl group referred to here indicates an alkyl group at the alkyl ester moiety of the (meth) acrylic acid alkyl ester, and may be either linear or branched.

In the non-crosslinkable (meth) acrylic acid ester unit (a1), the (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and the (meth) acrylic having an alkyl group having 3 or more carbon atoms. The content ratio of the acid alkyl ester unit is not particularly limited.

For example, even after the pressure-sensitive adhesive layer is post-hardened, the cohesive force of the polymer component is likely to increase, foaming is likely to be suppressed, and the blister resistance performance of the pressure-sensitive adhesive sheet is likely to be improved. , Can be done as follows. That is, with respect to the total mass of the (meth) acrylic acid alkyl ester unit having 2 or less carbon atoms in the alkyl group and the (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms in the alkyl group, the alkyl group The (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms is preferably 40% by mass or more, more preferably 45% by mass or more, further preferably 50% by mass or more, and 54% by mass. % Or more is particularly preferable, 95% by mass or less is preferable, 90% by mass or less is more preferable, and 85% by mass or less is further preferably 80% by mass or less. Is particularly preferable.

Hereinafter, the structural unit (a2) having an acidic functional group contained in the crosslinkable acrylic copolymer (A) in the pressure-sensitive adhesive sheet A and the crosslinkable acrylic copolymer (A) in the pressure-sensitive adhesive sheet B will be described.

In the structural unit (a2) having an acidic functional group, the acidic functional group is an acidic group, and in particular, it is a functional group capable of advancing the crosslinking reaction by the crosslinking agent (B) described later. Examples of such an acidic functional group include a carboxy group or a group derived from a carboxy group, a sulfo group or a group derived from a sulfo group, and the acidic functional group is preferably a carboxy group. That is, the structural unit (a2) having an acidic functional group is preferably a structural unit derived from the carboxy group-containing monomer. In this case, the adhesive sheet tends to have higher adhesive strength and also tends to have particularly improved durability, so that the blister resistance becomes more excellent. Examples of the carboxy group-containing monomer include acrylic acid and methacrylic acid. One of these may be used alone, or two or more thereof may be used in combination.

As described above, the content ratio of the structural unit (a2) is 5 to 15% by mass with respect to all the structural units contained in the crosslinkable acrylic copolymer (A). As a result, the adhesive sheet tends to have higher adhesive strength and also tends to improve durability. The content ratio of the structural unit (a2) is more preferably 5 to 10% by mass with respect to all the structural units contained in the crosslinkable acrylic copolymer (A).

The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B has, in addition to the non-crosslinkable (meth) acrylic acid ester unit (a1) and the structural unit having an acidic functional group (a2), still other constituents. It can also include units. As other structural units, for example, structural units derived from a monomer copolymerizable with an acrylic monomer can be broadly mentioned, and specifically, (meth) acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl. Examples thereof include pyrrolidone and vinyl pyridine. As another structural unit, a monomer having a crosslinkable functional group other than the acidic functional group can be included. Examples of the crosslinkable functional group other than the acidic functional group include a hydroxy group, an amino group, an amide group, a glycidyl group and an isocyanate group. The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B is a polymer formed of (meth) acrylic structural units, and is a non-crosslinkable (meth) acrylic acid ester unit (a1). ) And a copolymer other than the copolymer containing the structural unit (a2) having an acidic functional group.

The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B is a copolymer composed of only a non-crosslinkable (meth) acrylic acid ester unit (a1) and a structural unit (a2) having an acidic functional group. It can also be. The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B is usually a random copolymer.

The weight average molecular weight of the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B is preferably 200,000 to 2,000,000, more preferably 300,000 to 1,500,000. When the weight average molecular weight is within the above range, it is easy to maintain the semi-cured state of the pressure-sensitive adhesive layer, and it is easy to obtain the hardness after post-curing, and the processability is excellent. The weight average molecular weight of the crosslinkable acrylic copolymer (A) is a value before cross-linking with a cross-linking agent. The weight average molecular weight is a value measured by size exclusion chromatography (SEC) and determined based on polystyrene. As the crosslinkable acrylic copolymer, a commercially available one may be used, or one synthesized by a known method may be used.

The method for producing the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B is not particularly limited, and for example, the same method as for producing a known acrylic copolymer can be adopted.

For example, a (meth) acrylic acid alkyl ester for forming a non-crosslinkable (meth) acrylic acid ester unit (a1) and a carboxy group-containing monomer for forming a structural unit (a2) having an acidic functional group. A crosslinkable acrylic copolymer (A) can be produced by a polymerization reaction of a monomer mixture containing and. The conditions of the polymerization reaction are not particularly limited, and for example, known polymerization reactions can be widely adopted.

The crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet A has a glass transition temperature in the range of -40 to -20 ° C. As a result, the cohesive force of the polymer component is increased in the pressure-sensitive adhesive layer, and foaming is easily suppressed. As a result, the blister resistance performance of the pressure-sensitive adhesive sheet is likely to be improved.

The glass transition temperature of the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet A preferably exceeds −40 ° C. (that is, does not include −40 ° C.), and more preferably −35 ° C. or higher. .. The glass transition temperature of the crosslinkable acrylic copolymer (A) is preferably less than −20 ° C., more preferably −25 ° C. or lower.

The method for adjusting the glass transition temperature of the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet A is not particularly limited, and for example, a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms. Examples thereof include a method of adjusting the content ratio of the (meth) acrylic acid alkyl ester unit having 3 or more carbon atoms and the structural unit (a2) having an acidic functional group.

In the present specification, the glass transition temperature of the crosslinkable acrylic copolymer (A) refers to Tg determined by the following Fox formula based on the composition of the monomer used for the synthesis of the copolymer. Fox formula: 1 / Tg = (W1 / Tg1) + (W2 / Tg2) + ... + (Wm / Tgm)
Here, W1 + W2 + ... + Wm = 1
In the formula, Tg is the glass transition temperature (unit: K) of the crosslinkable acrylic copolymer (A), and Tg1, Tg2, ..., Tgm are m types constituting the crosslinkable acrylic copolymer (A). The glass transition temperature of each homopolymer of the monomer (m is an integer), and W1, W2, ..., Wm are the mass fractions of each structural unit in the crosslinkable acrylic copolymer (A). .. It should be noted that Tg1 and W1 have a corresponding relationship with each other, that is, the monomer constituting the homopolymer showing the glass transition temperature of Tg1 is the same as the monomer for forming the structural unit having a mass fraction of W1. be. Similarly, Tg2 and W2, ... Tgm and Wm are in a corresponding relationship with each other.

As the glass transition temperature of the above-mentioned homopolymer, for example, the value described in Polymer Handbook 4th Edition (Wiley-Interscience 2003) can be used. Unless otherwise stated in such handbooks, the glass transition temperature of homopolymers can be measured, for example, by a differential scanning calorimeter (DSC). The measurement conditions for DSC are a sample of 5 mg and a nitrogen atmosphere. In the first measurement (1st RUN), the temperature rises from -100 ° C to 200 ° C at a temperature rise rate of 5 ° C / min, and then the temperature drops at 5 ° C / min. Then, in the second measurement (2nd RUN), the temperature is raised from -100 ° C to 200 ° C at a heating rate of 5 ° C / min. Here, the glass transition temperature is lower than the region where the baseline of the DSC curve measured when the temperature is raised from -100 ° C to 200 ° C in the 2nd RUN changes to the sigmoid type in the heat absorption direction. It refers to the intersection of the extension of the baseline on the side and the tangent of the inflection in the sigmoid.

The glass transition temperature (Tg) of the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheet B is not particularly limited. The glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to -40 in that the cohesive force of the polymer component is increased in the pressure-sensitive adhesive layer, foaming is easily suppressed, and the blister resistance performance of the pressure-sensitive adhesive sheet is easily improved. It is preferably in the range of −20 ° C. The glass transition temperature of the crosslinkable acrylic copolymer (A) preferably exceeds −40 ° C. (that is, does not include −40 ° C.), and more preferably −35 ° C. or higher. The glass transition temperature of the crosslinkable acrylic copolymer (A) is preferably less than −20 ° C., more preferably −25 ° C. or lower.

Hereinafter, each component other than the crosslinkable acrylic copolymer (A) contained in the pressure-sensitive adhesive sheets A and B will be described. Since each of these components is common to the pressure-sensitive adhesive sheets A and B, the components contained in the pressure-sensitive adhesive sheets A and B will be collectively described below.

(Crosslinking agent B)
The cross-linking agent (B) is not particularly limited as long as it can promote the cross-linking reaction of the cross-linking acrylic copolymer, and for example, a known cross-linking agent can be widely used. For example, the cross-linking agent (B) can be selected from known cross-linking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds. Among these, it is preferable to use an epoxy compound because the carboxy group-containing acrylate can be easily crosslinked. That is, the cross-linking agent is preferably a bifunctional or higher functional epoxy compound.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol di. Glycyzyl ether, tetraglycidyl xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected according to the desired adhesiveness and the like, but is 0.01 to 5 parts by mass with respect to 100 parts by mass of the cross-linking acrylic copolymer (A). Is preferable, and 0.01 to 3 parts by mass is more preferable. By setting the content of the cross-linking agent (B) within the above range, the adhesion to the substrate can be enhanced and the processability can be further enhanced. The cross-linking agent (B) may be used alone or in combination of two or more, and when two or more of them are used in combination, the total mass is preferably within the above range.

(Polyfunctional monomer (C))
The polyfunctional monomer (C) is a compound having two or more polymerizable double bonds in the molecule. By including the polyfunctional monomer (C) in the pressure-sensitive adhesive composition, a radical polymerization reaction of the polyfunctional monomer (C), particularly, when the semi-cured pressure-sensitive adhesive layer is post-cured. The cross-linking reaction proceeds, whereby the pressure-sensitive adhesive layer is post-cured and becomes a post-cured state.

The polyfunctional monomer (C) is, for example, di (meth) acrylic acid ethylene glycol, di (meth) acrylic acid triethylene glycol, di (meth) acrylic acid 1,3-butylene glycol, di (meth) acrylic acid. 1,4-butylene glycol, di (meth) acrylic acid 1,9-nonanediol, diacrylic acid 1,6-hexanediol, di (meth) acrylic acid polybutylene glycol, di (meth) acrylic acid neopentyl glycol, di Tetraethylene glycol (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, diacrylate of bisphenol A diglycidyl ether, trimethylol propane tri (meth) acrylate, tri (meth) ) Pentaerythritol acrylate, (meth) acrylic acid esters of polyhydric alcohols such as pentaerythritol tetra (meth) acrylate, vinyl methacrylate and the like can be mentioned. These may be used alone or in combination of two or more.

The polyfunctional monomer (C) has 2 or more polymerizable double bonds, preferably 2 or more and less than 5, and more preferably 2 or more and less than 4.

As the polyfunctional monomer (C), for example, a commercially available product can be used. Commercially available products include the trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) manufactured by Toa Synthetic Co., Ltd., the trifunctional monomer M321 (trimethylolpropane propylene oxide-modified triacrylate), and the bifunctional monomer M211B (bisphenol) manufactured by Toa Synthetic Co., Ltd. A EO-modified diacrylate) and the like.

The polyfunctional monomer (C) may have a bisphenol skeleton in one molecule. By using a polyfunctional monomer having a bisphenol skeleton in one molecule, the hardness of the pressure-sensitive adhesive layer after post-curing can be increased more effectively, and the processability of the pressure-sensitive adhesive sheet is likely to be improved. Examples of such polyfunctional monomer (C) include diaclate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, and diaclate of bisphenol F diglycidyl ether.

The glass transition temperature (Tg) when the polyfunctional monomer (C) is homopolymer is preferably 30 ° C. or higher, and more preferably 50 ° C. or higher. The glass transition temperature (Tg) when the polyfunctional monomer is homopolymer may be, for example, 300 ° C. or lower. By setting the glass transition temperature (Tg) when the polyfunctional monomer C is homopolymer in the above range, the processability of the pressure-sensitive adhesive sheet can be more effectively improved. As the glass transition temperature, the value in the literature may be adopted, but after the polyfunctional monomer (C) is made into a homopolymer having a weight average molecular weight of 10,000 or more, the glass transition temperature of the homopolymer is set to DSC (differential). A value measured using a scanning calorimetry meter) can be adopted.

In the pressure-sensitive adhesive composition, the polyfunctional monomer (C) is contained in an amount of 1 to 20 parts by mass per 100 mass of the crosslinkable acrylic copolymer (A). As a result, the post-curing treatment makes it difficult for the pressure-sensitive adhesive layer in the post-curing state to shrink and shrink, and as a result, the adhesive strength of the pressure-sensitive adhesive sheet is improved and the blister resistance is excellent. In particular, the crosslinkable acrylic copolymer (A) has a higher Tg than the conventional one and has a strong cohesive force of the polymer component, so that it is considered that curing shrinkage is likely to occur. However, on the contrary, in the present invention, when the polyfunctional monomer (C) is contained in a specific amount, such curing shrinkage is less likely to occur. As a result, it is possible to have excellent blister resistance while maintaining high adhesive strength of the adhesive sheet.

In the pressure-sensitive adhesive composition, the polyfunctional monomer (C) preferably contains more than 1 part by mass, more preferably 5 parts by mass or more, per 100 parts by mass of the crosslinkable acrylic copolymer (A). Further, the polyfunctional monomer (C) is preferably contained in an amount of 20 parts by mass or less, and more preferably 15 parts by mass or less per 100 parts by mass of the crosslinkable acrylic copolymer (A).

(Photopolymerization Initiator (D))
The pressure-sensitive adhesive composition contains a photopolymerization initiator (D). The photopolymerization initiator is preferably one that initiates the polymerization of the crosslinkable acrylic copolymer or the polyfunctional monomer by irradiation with active energy rays in the post-curing treatment. As the photopolymerization initiator (D), a known photopolymerization initiator can be used. The "active energy beam" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, electron beams, visible rays, X-rays, and ion beams. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.

Examples of the photopolymerization initiator (D) include an acetophenone-based initiator, a benzoin ether-based initiator, a benzophenone-based initiator, a hydroxyalkylphenone-based initiator, a thioxanthone-based initiator, an amine-based initiator, and an acylphosphine oxide-based initiator. Agents and the like can be mentioned.

Specific examples of the acetophenone-based initiator include diethoxyacetophenone and benzyldimethylketal. Specific examples of the benzoin ether-based initiator include benzoin, benzoin methyl ether and the like. Specific examples of the benzophenone-based initiator include benzophenone, methyl o-benzoylbenzoate, and the like.

Specific examples of the hydroxyalkylphenone-based initiator include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by IGM Resins BV, commercially available as Omnirad 184). Specific examples of the thioxanthone-based initiator include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone and the like. Specific examples of the amine-based initiator include triethanolamine, ethyl 4-dimethylbenzoate and the like. Specific examples of the acylphosphine oxide-based initiator include phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by IGM Resins VV, commercially available as Omnirad 819).

Other photopolymerization initiators (D) include, for example, 2,2-dimethoxy-2-phenylacetophenone, 1- [4- (2-hydroxyethoxyl) -phenyl] -2-hydroxy-methylpropanol, 2-hydroxy-. Alkylphenone-based photopolymerization initiators such as 1- (4- (4- (2-hydroxy-2-methylpropionyl) benzyl) phenyl) -2-methyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenyl In addition to acylphosphine oxide-based polymerization initiators such as phosphinoxide and 2,4,6-trimethylbenzoyl) phenylphosphinoxide, and intramolecular hydrogen abstraction-type photopolymerization initiators such as methyl benzoyllate and 4-methylbenzophenone. Examples thereof include an oxime ester-based photopolymerization initiator and a cationic photopolymerization initiator.

The content of the photopolymerization initiator (D) in the pressure-sensitive adhesive composition is preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic copolymer (A), preferably 0.1. It is more preferably to 5 parts by mass. Within the above range, the hardness can be adjusted to a desired level by post-curing, and the molecular weight after post-curing can be set to an appropriate range, so that a pressure-sensitive adhesive sheet having excellent processability can be obtained. As the photopolymerization initiator (D), one type may be used alone or two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

(solvent)
The pressure-sensitive adhesive composition may contain a solvent from the viewpoint of improving the coatability. Examples of the solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloropropane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone; methyl acetate , Ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate and other esters; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene. Examples thereof include polyols such as glycol monomethyl ether acetate and derivatives thereof.

When the pressure-sensitive adhesive composition contains a solvent, the content thereof is not particularly limited, and may be, for example, 25 to 500 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic copolymer (A), and 30 to 400 parts by mass. It is more preferable to use parts by mass. The content of the solvent is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the pressure-sensitive adhesive composition. One type of solvent may be used alone, or two or more types may be used in combination, and when two or more types are used in combination, the total mass is preferably within the above range.

(Method for preparing other ingredients and pressure-sensitive adhesive composition)
The pressure-sensitive adhesive composition contained in the pressure-sensitive adhesive sheets A and B may contain other components other than the above as long as the effects of the present invention are not impaired. Other components can include monofunctional monomers having one reactive double bond in the molecule. The type of such a monofunctional monomer is not particularly limited, and for example, a monofunctional monomer contained in a known pressure-sensitive adhesive composition can be widely used.

The pressure-sensitive adhesive composition contained in the pressure-sensitive adhesive sheets A and B can contain additives for various pressure-sensitive adhesives as long as the effects of the present invention are not impaired. Examples of such additives include plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like, if necessary. You can choose. Further, dyes and pigments may be added for the purpose of coloring.

Examples of the plasticizer include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprilate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, and benzoic acid. Examples thereof include carboxylic acid vinyl esters such as vinyl and styrene.

Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. One type of these antioxidants may be used alone, or two or more types may be used in combination.

As the metal corrosion inhibitor, a benzoriazole-based resin can be mentioned as a preferable example because of the compatibility and high effect of the pressure-sensitive adhesive.

Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, Kumaron inden resin, styrene resin, xylene resin, phenol resin, petroleum resin and the like.

Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto group-substituted alkoxy oligomer).

Examples of the ultraviolet absorber include benzotriazole-based compounds and benzophenone-based compounds. However, when ultraviolet rays are used as the active energy rays during post-curing, it is preferable to add them within a range that does not inhibit the polymerization reaction.

The method for preparing the pressure-sensitive adhesive composition contained in the pressure-sensitive adhesive sheets A and B is not particularly limited. For example, a crosslinkable acrylic copolymer (A), a crosslinker (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and a photopolymerization initiator (D). And, if necessary, a solvent, other components, and the like are mixed in a predetermined blending ratio to prepare a pressure-sensitive adhesive composition.

(Adhesive layer)
Hereinafter, the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheets A and B will be described. The pressure-sensitive adhesive layer is formed by putting the pressure-sensitive adhesive composition in a semi-cured state. That is, the pressure-sensitive adhesive layer contains a semi-cured product of the pressure-sensitive adhesive composition and has post-curing property.

The pressure-sensitive adhesive layer can be formed only of the semi-cured product of the pressure-sensitive adhesive composition, or the pressure-sensitive adhesive layer can include other than the semi-cured product of the pressure-sensitive adhesive composition as long as the effect of the present invention is not impaired. ..

In the present invention, when the gel fraction of the pressure-sensitive adhesive layer is increased by 10% by mass or more as compared with that before irradiation by irradiation with active energy rays, the pressure-sensitive adhesive layer before irradiation is considered to be in a semi-cured state. Irradiation of the active energy ray in this case is performed as follows. First, transparent optical PET separators are attached to both sides of the pressure-sensitive adhesive layer. Then, the active energy ray (high-voltage mercury lamp or metal halide lamp) is irradiated from one of the optical transparent PET separators so that the integrated light amount is 3000 mJ / cm ² . By measuring the gel fraction of the pressure-sensitive adhesive layer formed by this irradiation and examining whether or not the pressure-sensitive adhesive layer increased by 10% by mass or more before and after irradiation, it is possible to determine whether or not the pressure-sensitive adhesive layer before irradiation was in a semi-cured state. Can be done.

The gel fraction of the pressure-sensitive adhesive layer is a value measured by the following method. First, about 0.1 g of an adhesive sheet (adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and the mixture is shaken for 24 hours. Then, the contents of this sample bottle are filtered off with a 150 mesh stainless steel wire mesh, and the residue on the wire mesh is dried at 100 ° C. for 1 hour, and the dry mass (g) is measured. From the obtained dry mass, the following formula 1
Gel fraction (mass%) = (dry mass / collected mass of adhesive layer) x 100 ... Equation 1
Can be used to determine the gel fraction.

In the present invention, the "semi-cured state" is preferably a state after the pressure-sensitive adhesive composition is heat-cured. After this heat treatment, it is preferable to "post-cure" by irradiating with active energy rays. That is, the pressure-sensitive adhesive layer is preferably in a semi-cured state by thermally curing the pressure-sensitive adhesive composition, and preferably has active energy ray curability.

In the pressure-sensitive adhesive sheet of the present invention, the gel content of the pressure-sensitive adhesive layer was 50 to 80%, and the pressure-sensitive adhesive layer was irradiated with active energy rays so that the integrated light amount was 3000 mJ / cm ² , and then cured. The gel fraction in the case is preferably 75 to 90%. In this case, the adhesiveness is maintained even in the post-curing state, and the cohesive force of the polymer in the post-curing state of the pressure-sensitive adhesive layer can be enhanced. As a result, the pressure-sensitive adhesive layer can be used even in a high-temperature and high-humidity environment. Foaming can be suppressed. As a reminder, a gel fraction of 50-80% in the pressure-sensitive adhesive layer means a gel fraction of 50-80% in the semi-cured pressure-sensitive adhesive layer. The gel fraction of the pressure-sensitive adhesive layer is more preferably 60 to 80%, more preferably 65 to 80%. Further, when measuring the gel fraction after irradiating the pressure-sensitive adhesive layer with active energy rays and curing the adhesive layer, irradiation with the active energy rays is performed as follows. First, transparent optical PET separators are attached to both sides of the pressure-sensitive adhesive layer. Then, an active energy ray (high-pressure mercury lamp or metal halide lamp) is irradiated from one of the transparent PET separators for optics so that the integrated light amount becomes 3000 mJ / cm ² , and the gel fraction of the pressure-sensitive adhesive layer formed by this irradiation is measured. Measure.

The difference between the gel fraction in the semi-cured state and the gel fraction after post-curing of the pressure-sensitive adhesive layer is preferably 5% or more, and 20% or less, from the viewpoint of easily suppressing curing shrinkage. Is preferable.

The thickness of the adhesive layer can be appropriately set according to the application and is not particularly limited. For example, the thickness of the pressure-sensitive adhesive layer is preferably 5 to 150 μm, more preferably 8 to 100 μm, further preferably 10 to 80 μm, and particularly preferably 10 to 40 μm. By setting the thickness of the pressure-sensitive adhesive layer within each of the above ranges, it is possible to suppress the stickiness and stickiness of the pressure-sensitive adhesive, and thus the workability can be improved. Further, by setting the thickness of the pressure-sensitive adhesive layer within the above range, the pressure-sensitive adhesive sheet can be easily manufactured.

In the pressure-sensitive adhesive sheet of the present invention, when the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer is 5 N / 25 mm or more and the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light amount is 3000 mJ / cm ² and then cured. The adhesive strength of the above is preferably 10 N / 25 mm or more. This makes it possible to have excellent adhesion to the substrate even after the pressure-sensitive adhesive layer is post-cured. Also in this case, the adhesive strength of 5 N / 25 mm or more means that the adhesive strength of the adhesive layer in the semi-cured state is 5 N / 25 mm. Further, when measuring the adhesive strength after irradiating the pressure-sensitive adhesive layer with active energy rays and curing, the irradiation conditions of the active energy rays are the same as the irradiation conditions for measuring the post-cured gel fraction described above. be.

The adhesive strength of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive strength after the pressure-sensitive adhesive layer is post-cured strongly depend on the composition of the pressure-sensitive adhesive composition, and in particular, Tg of the crosslinkable acrylic copolymer (A) and a polyfunctional single amount. By forming the pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition in which the content ratio of the body (C) is adjusted to a predetermined range, the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive force after the pressure-sensitive adhesive layer is post-cured can be obtained. It can be made to the desired size.

The adhesive strength is a value measured by the following method. Postscript of the pressure-sensitive adhesive layer The second release sheet, which is a light separator film, is peeled off, attached to a PET film having a thickness of 50 μm, and cut into a width of 25 mm. After cleaning the non-tin surface of the float glass with ethanol, the first release sheet, which is the postscript heavy separator film of the adhesive sheet, is peeled off, and the adhesive surface of the adhesive sheet is attached to the glass by reciprocating a 2 kg roller. After the obtained sample having the composition of PET / adhesive layer / glass was autoclaved (40 ° C., 0.5 MPa, 30 min), the other end of this sample was peeled off at a rate of 300 mm / min in the peeling direction of 180 degrees. The adhesive force to the glass at that time is defined as the adhesive force of the adhesive layer (that is, the adhesive force of the semi-cured adhesive layer). On the other hand, a sample having the same PET / adhesive layer / glass configuration as described above is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are integrated from the PET film side so that the integrated light intensity becomes 3000 mJ / cm ² . To obtain a test sample. In this test sample, the other end of the adhesive sheet is peeled off at a rate of 300 mm / min in a peeling direction of 180 degrees, and the adhesive force to the glass at that time is post-cured (that is, after the adhesive layer is post-cured). (Adhesive strength (in a post-cured state)).

(Adhesive sheet)
As described above, the pressure-sensitive adhesive sheet of the present invention contains a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition. Therefore, the pressure-sensitive adhesive sheet of the present invention has post-curability, particularly active energy ray-curability.

The structure of the pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it has the pressure-sensitive adhesive layer, and can be, for example, the same structure as a known pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet can be a single-layer pressure-sensitive adhesive sheet composed of only the pressure-sensitive adhesive layer. Alternatively, the pressure-sensitive adhesive sheet may be a single-sided pressure-sensitive adhesive sheet having a base material (preferably a transparent base material) on one side, or may be a double-sided pressure-sensitive adhesive sheet.

Specific examples of the pressure-sensitive adhesive sheet include a single-layer pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer, a multi-layered pressure-sensitive adhesive sheet in which a plurality of pressure-sensitive adhesive layers are laminated, and a multilayer layer in which another pressure-sensitive adhesive layer is laminated between the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer. Adhesive sheet, a multi-layered adhesive sheet with a support laminated between the adhesive layers, and a multi-layered adhesive sheet with an adhesive layer laminated on one side of the support and another adhesive layer laminated on the other side. Adhesive sheet can be mentioned. When the pressure-sensitive adhesive sheet has a support, it is preferable to use a transparent support as the support. As the support, a general film used in the optical field can be used as in the case of the transparent substrate. Since such an adhesive sheet is also excellent in transparency of the adhesive sheet as a whole, it can be suitably used for adhesion between optical members.

When the pressure-sensitive adhesive sheet of the present invention is a single-sided pressure-sensitive adhesive sheet, as shown in FIG. 1, a transparent base material 12a may be provided on one side of the pressure-sensitive adhesive layer 11. In this case, it is preferable that the other surface of the pressure-sensitive adhesive layer 11 is covered with the release sheet 12b. When using an adhesive sheet, the release sheet 12b may be peeled off and attached to the desired adherend so that the adhesive layer 11 adheres to the desired adherend, and then post-cured by irradiating with active energy rays or the like. preferable. As the transparent substrate, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film can be used. Further, an easy-adhesion layer may be provided on the pressure-sensitive adhesive layer side of these transparent substrates. Further, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, and an ultraviolet absorbing layer may be provided on the opposite surface of the adhesive layer of the transparent base material.

The present invention includes an adhesive sheet with a release sheet provided with release sheets on both sides of the adhesive sheet. Such a pressure-sensitive adhesive sheet with a release sheet can be provided with a pair of release sheets having different peeling forces on both sides of the pressure-sensitive adhesive sheet. For example, as shown in FIG. 1, the release sheets 12a are provided on both sides of the pressure-sensitive adhesive layer 11. And 12b can have.

The release sheet is a removable laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity base material. Can be mentioned.

Paper and polymer films are used as the base material for the release sheet in the releaseable laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone-based release agent or a long-chain alkyl group-containing compound is used. In particular, a highly reactive additive silicone-based release agent is preferably used.

Specific examples of the silicone-based release agent include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., Ltd. and KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Be done. Further, the silicone-based release agent may contain a silicone resin which is an organic silicon compound having _{2 units of SiO and 1/2} _unit of (CH ₃ ) ₃ SiO or CH ₂ = CH (CH ₃ ) _1/2 unit of SiO. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3800, X92-183 manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

A commercially available product may be used as the peelable laminated sheet. For example, a heavy separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd., and a light separator film, which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Film Co., Ltd., can be mentioned.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it is preferable to have a pair of release sheets having different peeling forces. That is, it is preferable that the release sheet has different peelability between the release sheet 12a and the release sheet 12b in order to facilitate the release. When the peelability from one side and the peelability from the other side are different, it becomes easy to peel off only the peeling sheet having the higher peeling property first. In that case, the peelability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding order.

Further, the present invention may relate to an adhesive sheet with a transparent film provided with a transparent film on at least one surface of the adhesive sheet. In this case, the transparent film is preferably at least one selected from a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film and a cycloolefin polymer film. The pressure-sensitive adhesive sheet with a transparent film may be a sheet in which a transparent film / a pressure-sensitive adhesive sheet / a release sheet are laminated in this order.

The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and for example, a known method for manufacturing a pressure-sensitive adhesive sheet can be widely adopted. For example, by a manufacturing method including a step of applying the pressure-sensitive adhesive composition on a release sheet to form a coating film and a step of forming the coating film into a semi-cured product (semi-cured product) by heating. , The pressure-sensitive adhesive sheet of the present invention can be manufactured. In this case, by heating the coating film, the reaction between the crosslinkable acrylic copolymer (A) and the crosslinker (B) proceeds to form a semi-cured cured product (that is, an adhesive layer). During heating, the polymerization reaction of the monomer by the photopolymerization initiator (D) does not proceed in the coating film, or even if it progresses, it is slight, so that the pressure-sensitive adhesive layer is derived from the pressure-sensitive adhesive composition. At least a part of the polymerizable monomer (polyfunctional monomer (C) and the like) and the photopolymerization initiator (D) is contained in an unreacted state.

In order to make the pressure-sensitive adhesive composition semi-cured, it is preferable to perform an aging treatment in which the pressure-sensitive adhesive sheet is allowed to stand at a constant temperature for a certain period of time after the solvent is removed after coating. The aging treatment can be performed, for example, by allowing it to stand at 23 ° C. for 7 days.

The coating of the pressure-sensitive adhesive composition can be carried out using a known coating device. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater and the like.

A known heating device such as a heating furnace or an infrared lamp can be used to heat the coating film formed by applying the pressure-sensitive adhesive composition.

The method of using the adhesive sheet of the present invention is not particularly limited, and it can be used in various methods depending on the intended use and purpose. For example, the pressure-sensitive adhesive sheet is preferably used by a method in which the pressure-sensitive adhesive layer is brought into contact with the surface of the adherend. Specifically, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state, it is preferably bonded to the adherend and irradiated with active energy rays to post-cure the pressure-sensitive adhesive layer. Since the pressure-sensitive adhesive sheet of the present invention is a two-step curing type pressure-sensitive adhesive sheet, it has a pressure-sensitive adhesive layer that is semi-cured only by heat before bonding, and the pressure-sensitive adhesive layer is post-cured by active energy rays after bonding. Since it has a property, various usage methods suitable for this property can be adopted. The adherend is the same as the adherend in the laminated body described later.

Since the adhesive sheet of the present invention has high adhesive strength and excellent blister resistance, it is unlikely to float or peel off from the adherend even in a high temperature and high humidity environment, and has excellent adhesion and durability. Therefore, even if the adhesive sheet of the present invention is used for applications such as bonding large-screen optical members, wrinkles are less likely to occur and the workability is excellent.

Further, the pressure-sensitive adhesive sheet of the present invention suppresses the stickiness of the end face after post-curing, and can prevent, for example, the adhesion of the pressure-sensitive adhesive to the punching blade during the punching process and the resulting deformation of the pressure-sensitive adhesive layer. Further, the pressure-sensitive adhesive sheet of the present invention does not cause deformation, protrusion, peeling, etc. of the pressure-sensitive adhesive layer when cutting for the purpose of adjusting the end face after punching to a desired size after post-curing, and the workability is also improved. Are better.

The adhesive sheet of the present invention is excellent in adhesion to a base material and durability even when it is attached to an adherend such as a base material, post-cured, and then exposed to a high temperature and high humidity environment. Therefore, it is possible to suppress the occurrence of floating and peeling. The adhesive sheet of the present invention suppresses floating or peeling from the polycarbonate base material even when it is attached to a polycarbonate base material, post-cured, and then exposed to a high temperature and high humidity environment. can do.

In the present specification, the durability of the adhesive sheet can be evaluated by the following method. First, a triacetyl cellulose film is attached to one surface of the pressure-sensitive adhesive sheet, and a polycarbonate plate is attached to the other surface, and active energy rays are irradiated from the surface on the triacetyl cellulose film side so that the integrated light amount is 3000 mJ / cm ² . Then the pressure-sensitive adhesive layer is post-cured. Then, the adhesive sheet is allowed to stand in an environment of 85 ° C. and a relative humidity of 85% for 240 hours each. After that, the pressure-sensitive adhesive sheet is observed, and it can be determined that the durability is excellent when the adhesive sheet is prevented from floating or peeling off from the polycarbonate plate and / or the triacetyl cellulose film.

As described above, the adhesive sheet of the present invention is an optical member that requires durability, and is preferably used for bonding an optical member that requires molding after laminating with the optical member. The pressure-sensitive adhesive sheet of the present invention can also be used by being attached to an optical member such as a polarizing plate. The polarizing plate includes a polarizing element and a polarizing element protective film. The pressure-sensitive adhesive sheet of the present invention is preferably bonded to a polarizing element protective film. As the stator protective film, a resin film or the like can be widely used, for example, a cycloolefin resin film, a cellulose acetate resin film such as triacetyl cellulose or diacetyl cellulose, a polyester such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate. Examples thereof include a based resin film, a polycarbonate resin film, an acrylic resin film, and a polypropylene resin film.

When the adhesive sheet of the present invention is a double-sided adhesive sheet, it can be used for bonding two adherends. Examples of the case where the two adhesive sheets of the present invention are used for bonding the transparent optical films inside the touch panel are bonded to each other, the transparent optical film and the glass are bonded, and the transparent optical of the touch panel is used. Examples include bonding a film and a liquid crystal panel, bonding a cover panel and a transparent optical film, and bonding a cover panel and a transparent optical film, and in particular, when one of the members is a polycarbonate base material. It is useful for. As the transparent optical film, a general film used in the optical field such as a polyethylene terephthalate film, an acrylic film, a polycarbonate film, a triacetyl cellulose film, and a cycloolefin polymer film can be used. Further, the transparent optical film or the polycarbonate base material may be provided with a hard coat layer. Examples of the cover panel include resin and glass.

2. 2. Laminated Body The present invention includes a laminated body having the above-mentioned pressure-sensitive adhesive sheet and an adherend. Such a laminate has a pressure-sensitive adhesive sheet of the present invention and an adherend provided on at least one surface side of the pressure-sensitive adhesive sheet. In the laminated body, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state, that is, the pressure-sensitive adhesive layer in a semi-cured state is post-cured.

In the laminated body of the present invention, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state by irradiating it with active energy rays. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the two adherends are bonded to each other with a semi-cured pressure-sensitive adhesive sheet, irradiated with active energy rays, and the pressure-sensitive adhesive layer is post-cured to form a laminated body. It is preferable to do so. Here, examples of at least one of the adherends include a base material, an optical member, and the like, and more specifically, a resin plate, a resin film, glass, and the like are exemplified, and a known polarizing plate and the like are also exemplified. Ru. The adherend may have a single-layer structure or a laminated structure formed by laminating different materials.

In the laminated body, it is particularly preferable that at least one of the adherends is a resin plate. Examples of the resin film include known transparent films. When the adherends are laminated on both sides of the pressure-sensitive adhesive sheet, the adherends may be of the same type or different types.

In the present specification, the resin plate can mean a member having a thickness of 250 μm or more, and the resin film can mean a member having a thickness of less than 250 μm. In the laminated body of the present invention, the thickness of the adherend is not particularly limited. Therefore, for example, a resin plate having a thickness of 250 μm or more can be applied as the adherend, or a resin having a thickness of less than 250 μm can be applied. Films can also be applied.

The type of the resin plate is not particularly limited, and for example, a base material formed of a known resin can be widely used, and examples thereof include a polycarbonate (PC) plate, a polymethacrylate (PMMA) plate, and Mitsubishi Gas. Examples include the chemical "Iupilon MR58", the Kuraray "Polycarbonate MT3LTR", and the Teijin "Panlite PC1151". Further, the resin plate may have a laminated structure made of different materials, and may have, for example, a PMMA / PC two-kind two-layer structure and a PMMA / PC / PMMA two-kind three-layer structure. .. The resin plate may have a known hard coat layer.

FIG. 2 is a schematic view showing a cross section of an example of the laminated body of the present invention. FIG. 2 is a cross-sectional view showing an example of the configuration of a laminated body 20 in which the pressure-sensitive adhesive sheet 21 of the present invention is bonded to the base material 22 and the optical member 24. As shown in FIG. 2, the pressure-sensitive adhesive sheet 21 of the present invention is preferably used for bonding to the base material 22, and may be used for bonding the base material 22 to another optical member 24. preferable. The pressure-sensitive adhesive sheet 21 of the present invention may be used for bonding to a polarizing plate.

In the laminated body, when at least one of the adherends is an optical member, the optical member includes a shatterproof film attached to each component of an optical product such as a touch panel or an image display device, and a cover lens on the outermost layer. Can be mentioned. Examples of the constituent members of the touch panel include an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, and a transparent conductive film in which a transparent resin film is coated with a conductive polymer. Examples include hard coat films and fingerprint resistant films. Examples of the constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a luminance improving film used in a liquid crystal display device. Examples of the material used for these members include glass, polycarbonate, polyethylene terephthalate, polymethylmethacrylate, polyethylene naphthalate, cycloolefin polymer, triacetylcellulose, polyimide, and cellulose acylate.

FIG. 3 is a schematic view showing a cross section of another example of the laminated body of the present invention. As shown in FIG. 3, the adherend may have stepped portions (27a, 27b, 27c, 27d). In FIG. 3, the base material has a stepped portion (27a, 27b), and the optical member has a stepped portion (27c, 27d). The thickness of the stepped portion (27a, 27b, 27c, 27d) is usually 5 to 60 μm. As described above, the adhesive sheet 21 of the present invention can be attached to a member having a stepped portion, and can follow the unevenness generated from the stepped portion.

The manufacturing method of the laminated body is not particularly limited. For example, a step 1 of laminating an adherend on at least one surface side of the pressure-sensitive adhesive sheet of the present invention, and a step of post-curing the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays. A laminated body can be manufactured by a manufacturing method including 2 in this order. Before the irradiation with the active energy rays, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state, so that the initial adhesion to the substrate is good. In this way, after the pressure-sensitive adhesive sheet is attached to the adherend, the pressure-sensitive adhesive layer is post-cured with active energy rays, so that the cohesive force of the pressure-sensitive adhesive layer is enhanced and the adhesiveness to the adherend is improved. Further, the post-cured pressure-sensitive adhesive layer can prevent the base material from being deformed or distorted.

In the present invention, examples of the active energy ray include ultraviolet rays, electron beams, visible rays, X-rays, ion beams and the like, which can be appropriately selected depending on the photopolymerization initiator contained in the pressure-sensitive adhesive layer. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.

As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, etc. can be used.

As the electron beam, for example, an electron beam emitted from each type of electron beam accelerator such as Cockloftwald type, Bandeclaf type, resonance transformer type, insulated core transformer type, linear type, dynamitron type, high frequency type is used. can.

The irradiation output of ultraviolet rays is preferably such that the integrated light amount is 100 to 10000 mJ / cm ² , and more preferably 500 to 5000 mJ / cm ² .

The method for manufacturing the laminated body may further include a step of processing the laminated body after the step 2. In this step, for example, various processing can be performed on the laminated body, and specific examples thereof include punching processing and cutting processing. The processing method is not particularly limited, and for example, a known processing method can be widely adopted.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the embodiments of these Examples.

(Production Example 1: Synthesis of Crosslinkable Acrylic Copolymer (A-1))
As shown in the formulation table of Table 1, a crosslinkable acrylic copolymer (A-1) was prepared by a polymerization reaction of the polymerizable monomer. More specifically, the butyl acrylate monomer (hereinafter, “BA”) as the (meth) acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms, and the (meth) acrylic acid alkyl having an alkyl group having 2 or less carbon atoms. A methyl acrylate monomer (hereinafter, “MA”) was prepared as an ester, and acrylic acid (hereinafter, “AA”) was prepared as a carboxy group-containing monomer, and the mass ratio (70: 22: 8) shown in Table 1 was used. A monomer mixture was prepared by mixing so as to be. This monomer mixture was dissolved in ethyl acetate, and the polymerization reaction was carried out at 60 ° C. in the presence of AIBN (azobisisobutyronitrile) as a radical polymerization initiator. As a result, a crosslinkable acrylic copolymer (A-1) was obtained. In the obtained crosslinkable acrylic copolymer (A-1), the glass transition temperature (Tg) determined by using the FOX formula was −33 ° C.

(Production Example 2: Synthesis of Crosslinkable Acrylic Copolymer (A-2))
BA as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, an ethyl acrylate monomer (hereinafter, “EA”) as a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group, and , AA was prepared as a carboxy group-containing monomer and mixed so as to have the mass ratios shown in Table 1 to prepare a monomer mixture. A coalescence (A-2) was obtained. In the obtained crosslinkable acrylic copolymer (A-2), the glass transition temperature (Tg) determined by using the FOX formula was −28 ° C.

(Production Example 3: Synthesis of Crosslinkable Acrylic Copolymer (A-3))
BA as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, a methyl methacrylate monomer (hereinafter, “MMA”) as a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group, and , AA was prepared as a carboxy group-containing monomer and mixed so as to have the mass ratios shown in Table 1 to prepare a monomer mixture. Crosslinkable acrylic copolymer weight was prepared by the same method as in Production Example 1. A coalescence (A-3) was obtained. In the obtained crosslinkable acrylic copolymer (A-3), the glass transition temperature (Tg) determined by using the FOX formula was −25 ° C.

(Production Example 4: Synthesis of Crosslinkable Acrylic Copolymer (A-4))
BA as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, MA as a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group, and AA as a carboxy group-containing monomer. A crosslinkable acrylic copolymer (A-4) was obtained in the same manner as in Production Example 1 except that the monomers were prepared and mixed so as to have the mass ratios shown in Table 1. .. In the obtained crosslinkable acrylic copolymer (A-4), the glass transition temperature (Tg) determined by using the FOX formula was −26 ° C.

(Production Example 5: Synthesis of Crosslinkable Acrylic Copolymer (a-1))
BA as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, MA as a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group, and hydroxyethyl acrylate (hereinafter, "HEA"). ”) Was prepared, and the crosslinkable acrylic copolymer (a-1) was prepared by the same method as in Production Example 1 except that each was mixed so as to have the mass ratio shown in Table 1 to prepare a monomer mixture. Obtained. In the obtained crosslinkable acrylic copolymer (a-1), the glass transition temperature (Tg) determined by using the FOX formula was −39 ° C.

(Production Example 6: Synthesis of Crosslinkable Acrylic Copolymer (a-2))
Acrylic acid-2-ethylhexyl (hereinafter, "2EHA") is prepared as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, and AA is prepared as a carboxy group-containing monomer, and each is shown in Table 1. A crosslinkable acrylic copolymer (a-2) was obtained by the same method as in Production Example 1 except that the monomer mixture was prepared by mixing so as to have the indicated mass ratio. In the obtained crosslinkable acrylic copolymer (a-2), the glass transition temperature (Tg) determined by using the FOX formula was −60 ° C.

(Production Example 7: Synthesis of Crosslinkable Acrylic Copolymer (a-3))
BA as a (meth) acrylic acid alkyl ester having 3 or more carbon atoms in an alkyl group, MA and MMA as a (meth) acrylic acid alkyl ester having 2 or less carbon atoms in an alkyl group, and a carboxy group-containing monomer. The crosslinkable acrylic copolymer (a-3) was prepared in the same manner as in Production Example 1 except that AA was prepared as an ester and mixed so as to have the mass ratios shown in Table 1 to prepare a monomer mixture. Obtained. In the obtained crosslinkable acrylic copolymer (a-3), the glass transition temperature (Tg) determined by using the FOX formula was −44 ° C.

(Example 1)
As shown in Table 2, 100 parts by mass of the crosslinkable acrylic copolymer (A-1) obtained in Production Example 1 as the crosslinkable acrylic copolymer (A) and an epoxy-based compound as the crosslinker (B). (Tetrad X manufactured by Mitsubishi Gas Chemicals Co., Ltd.) in an amount of 0.1 part by mass (denoted as epoxy in Table 2) and ethylene oxide-modified diacrylate (manufactured by Toa Synthetic Co., Ltd., Aronix M211B) as a polyfunctional monomer (C). 7 parts by mass of Tg = 75 ° C.) and 0.5 part by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad 184, manufactured by IGM Resins B.V.) as the photopolymerization initiator (D) were mixed. An ethyl acetate was added as a solvent so that the solid content concentration was 40% by mass to prepare a pressure-sensitive adhesive composition.

The above pressure-sensitive adhesive composition was applied onto a first release sheet (heavy separator film, Teijin DuPont Film Co., Ltd., release-treated polyethylene terephthalate film). The coating was carried out using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. so that the thickness after drying was 15 μm. Then, it was dried in a hot air dryer at 100 ° C. for 3 minutes to remove the solvent, and a pressure-sensitive adhesive sheet having a semi-cured pressure-sensitive adhesive layer was formed.

A second release sheet (light separator film, manufactured by Teijin DuPont Film Co., Ltd.), which has been subjected to a mold release treatment that is more peelable than the first release sheet, is attached to one side of this adhesive sheet, and the adhesive sheet with the release sheet is used. I got an adhesive sheet.

(Example 2)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the amount of the polyfunctional monomer (C) used was changed to 12 parts by mass.

(Example 3)
The amount of the polyfunctional monomer (C) used was changed to 5 parts by mass, and the photopolymerization initiator (D) was changed to phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (IRGACURE819, manufactured by BASF Japan Ltd.). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except for the modification.

(Example 4)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 3 except that the amount of the polyfunctional monomer (C) used was changed to 3 parts by mass.

(Example 5)
Adhesive composition in the same manner as in Example 4 except that the polyfunctional monomer (C) was changed to 7 parts by mass of trimethylolpropane propylene oxide-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M321, Tg = 50 ° C.). An adhesive sheet with an object and a release sheet was obtained.

(Example 6)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (A-2) obtained in Production Example 2, and the photopolymerization initiator (D) was changed to phenylbis (2,4,6-trimethyl). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the mixture was changed to benzoyl) phosphin oxide (Omnirad 819, manufactured by BASF Japan).

(Example 7)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (A-3) obtained in Production Example 3, and the photopolymerization initiator (D) was changed to phenylbis (2,4,6-trimethyl). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the mixture was changed to benzoyl) phosphin oxide (Omnirad 819, manufactured by BASF Japan).

(Example 8)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (A-4) obtained in Production Example 4, and the amount of the crosslinker (B) used was changed to 0.05 parts by mass. The pressure-sensitive adhesive composition and release sheet are the same as in Example 1 except that the photopolymerization initiator (D) is changed to phenylbis (2,4,6-trimethylbenzoyl) phosphinoxide (Omnirad 819, manufactured by BASF Japan). I got an adhesive sheet with.

(Comparative Example 1)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the amount of the polyfunctional monomer (C) used was changed to 25 parts by mass.

(Comparative Example 2)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (A-3) obtained in Production Example 3, and the polyfunctional monomer (C) was changed to polyethylene glycol # 200 diacrylate (Shin Nakamura). A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the pressure was changed to 30 parts by mass (A-200, Tg = 50 ° C., manufactured by Chemical Industry Co., Ltd.).

(Comparative Example 3)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (a-1) obtained in Production Example 5, and the xylylene diisocyanate compound (Takenate D, manufactured by Mitsui Chemicals, Inc.) was used as the crosslinking agent (B). -110N) A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the content was changed to 0.2 parts by mass (referred to as isocyanate in Table 2).

(Comparative Example 4)
The adhesive composition and the release sheet were attached in the same manner as in Example 1 except that the crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (a-2) obtained in Production Example 6. Obtained an adhesive sheet.

(Comparative Example 5)
The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (a-3) obtained in Production Example 7, and the amount of the crosslinker (B) used was changed to 0.05 parts by mass. Adhesive in the same manner as in Example 1 except that the amount of the polyfunctional monomer (C) used was changed to 15 parts by mass and the amount of the photopolymerization initiator (D) used was changed to 0.7 parts by mass. An adhesive sheet with the composition and a release sheet was obtained.

(Measurement and evaluation)
<Gel fraction>
The pressure-sensitive adhesive layer was cut to a size of 100 mm × 60 mm to prepare a semi-cured measurement sample. Further, the adhesive layer is cut to a size of 100 mm × 60 mm, and ultraviolet rays are irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light amount is 3000 mJ / cm ² , and the measurement is performed after post-curing. A sample was prepared.

Approximately 0.1 g of an adhesive sheet for the measurement sample in the semi-cured state and the measurement sample after post-curing (indicated as "before curing" and "after curing" in Table 2, respectively) was collected in a sample bottle and ethyl acetate was collected. 30 ml was added and shaken for 24 hours. Then, the contents of this sample bottle were filtered off with a 150 mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100 ° C. for 1 hour, and the dry mass (g) was measured. From the obtained dry mass, the following formula 1
Gel fraction (mass%) = (dry mass / collected mass of adhesive sheet) x 100 ... Equation 1
The gel fraction was determined by.

<Adhesive strength>
The second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off, attached to a PET film having a thickness of 50 μm, and cut into a width of 25 mm. After cleaning the non-tin surface of the float glass with ethanol, the first release sheet, which is a heavy separator film of the adhesive sheet, was peeled off, and the adhesive surface of the adhesive sheet was attached to the glass by reciprocating a 2 kg roller. After the obtained sample having the composition of PET / adhesive layer / glass was autoclaved (40 ° C., 0.5 MPa, 30 min), the other end of this sample was peeled off at a rate of 300 mm / min in the peeling direction of 180 degrees. , The adhesive force to the glass at that time (that is, the adhesive force of the adhesive layer in the semi-cured state; in Table 2, indicated as before curing) was measured. On the other hand, a sample having the same PET / adhesive layer / glass configuration as described above is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are integrated from the PET film side so that the integrated light intensity becomes 3000 mJ / cm ² . To obtain a test sample. In this test sample, the other end of the pressure-sensitive adhesive sheet is peeled off at a rate of 300 mm / min in a peeling direction of 180 degrees, and the adhesive force against the glass at that time (that is, after the pressure-sensitive adhesive layer is post-cured (in a post-cured state)). Adhesive strength (indicated as after curing in Table 2) was measured.

<Durability test 1>
The second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and attached to a triacetyl cellulose film (manufactured by FUJIFILM Corporation, Fujitac TD60UL, thickness 60 μm). Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC plate having a thickness of 1 mm (polycarbonate plate having no hard coat layer: Teijin's "Panlite PC1151"). The sample of the composition of the triacetyl cellulose film / adhesive layer / PC board is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are emitted from the triacetyl cellulose film side so that the integrated light amount becomes 3000 mJ / cm ² . Was irradiated to obtain a test sample having a size of 100 mm × 200 mm. This test sample was allowed to stand in an environment of 85 ° C. and a relative humidity of 85% for 240 hours each.

After that, the test sample was observed, the presence or absence of errors (floating and peeling) was observed, and the durability was evaluated according to the following evaluation criteria.
A: No error was confirmed and it had excellent durability.
B: An error of 1 mm or less was confirmed in some parts.
An error exceeding C: 1 mm was confirmed.

<Durability test 2>
Durability was evaluated by the same method and standard as in durability test 1 except that the thickness of the PC plate was changed to 2 mm.

<Workability>
The second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and bonded to a PET film having a thickness of 25 μm. Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC plate. The sample having the composition of PET / adhesive layer / PC thus obtained is autoclaved (40 ° C., 0.5 MPa, 30 min), and then ultraviolet rays are emitted from the PET film side so that the integrated light amount becomes 3000 mJ / cm ² . Was irradiated to obtain a test sample. Next, the end portion of the test sample was cut using a guillotine cutting machine, and the cut end portion was rubbed by hand so as to peel off the PET film from the PC plate side. The workability was evaluated by measuring the peeling distance at that time.
A: The peeling distance was less than 0.05 mm, and it had excellent workability.
B: The peeling distance was 0.05 mm or more and less than 0.1 mm.
C: The peeling distance was 0.1 mm or more.

Table 2 shows the results of each evaluation in addition to the conditions for producing the pressure-sensitive adhesive sheets of the above-mentioned Examples and Comparative Examples. From Table 2, the adhesive sheet obtained in the examples has high adhesive strength, excellent blister resistance, is less likely to float or peel from the adherend even in a high temperature and high humidity environment, and has adhesiveness and durability. It was shown to be excellent in sex. In addition, the pressure-sensitive adhesive sheet of the example had good processability. On the other hand, the pressure-sensitive adhesive sheet of the comparative example was inferior in substrate adhesion (adhesive strength) and durability.

Claims

A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition comprises a crosslinkable acrylic copolymer (A), a crosslinker (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and photopolymerization. The crosslinkable acrylic copolymer (A) containing the initiator (D) contains a structural unit (a2) having an acidic functional group, and the content ratio of the structural unit (a2) is the crosslinkable property. It is 5 to 15% by mass with respect to all the constituent units contained in the acrylic copolymer (A).
The crosslinkable acrylic copolymer (A) has a glass transition temperature of −40 to −20 ° C.
A pressure-sensitive adhesive sheet containing 1 to 20 parts by mass of the polyfunctional monomer (C) per 100 mass of the crosslinkable acrylic copolymer (A).
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition comprises a crosslinkable acrylic copolymer (A), a crosslinker (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and photopolymerization. The crosslinkable acrylic copolymer (A) contains an initiator (D), and the crosslinkable acrylic copolymer (A) contains a non-crosslinkable (meth) acrylic acid ester unit (a1) and a structural unit (a2) having an acidic functional group. It is a copolymer and
The non-crosslinkable (meth) acrylic acid ester unit (a1) includes a (meth) acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and an alkyl group having 3 or more carbon atoms (meth). Contains acrylic acid alkyl esters,
The content ratio of the structural unit (a2) is 5 to 15% by mass with respect to all the structural units contained in the crosslinkable acrylic copolymer (A).
A pressure-sensitive adhesive sheet containing 1 to 20 parts by mass of the polyfunctional monomer (C) per 100 mass of the crosslinkable acrylic copolymer (A).
The gel fraction of the pressure-sensitive adhesive layer is 50 to 80%, and
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light amount is 3000 mJ / cm 2 , and then cured, and the gel fraction is 75 to 90%.
The adhesive strength of the pressure-sensitive adhesive layer is 5 N / 25 mm or more, and the pressure-sensitive adhesive layer is 5 N / 25 mm or more.
6 . Adhesive sheet.
A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different peeling forces on both sides of the pressure-sensitive adhesive sheet according to any one of claims 1 to 4.
It has the adhesive sheet according to any one of claims 1 to 4 and an adherend provided on at least one surface side of the adhesive sheet.
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is a laminated body in a post-cured state.
The laminate according to claim 6, wherein the adherend is at least one selected from the group consisting of a resin plate and a resin film.
Step 1 of laminating the adherend on at least one surface side of the pressure-sensitive adhesive sheet according to any one of claims 1 to 4, and
A method for producing a laminated body, comprising the step 2 of post-curing the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays.
The method for manufacturing a laminate according to claim 8, further comprising a step of processing the laminate after the step 2.
The method for producing a laminate according to claim 7 or 8, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 150 μm.