JP2022174182A - Adhesive sheet, adhesive sheet with release sheet, multilayer body, and method for producing multilayer body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an adhesive sheet which has high adhesive power and excellent blister resistance; a release sheet-attached adhesive sheet and a multilayer body, each of which comprises the adhesive sheet; and a method for producing the multilayer body.

SOLUTION: An adhesive sheet comprises an adhesive layer that contains a semi-cured product of an adhesive composition. 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). The crosslinkable acrylic copolymer (A) comprises a constituent unit (a2) having an acidic functional group. A content of the constituent units (a2) is 5-15 mass% based on all constituent units contained in the crosslinkable acrylic copolymer (A). A glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to -20°C. A content of the polyfunctional monomer (C) is 5-20 pts.mass per 100 pts.mass of the crosslinkable acrylic copolymer (A).

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet with a release sheet, a laminate, and a method for producing a laminate.

2. Description of the Related Art 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.
A transparent adhesive sheet is also used to bond the display device and the input device together.

A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive sheet for optical members is produced by a known polymerization method. Examples of this polymerization method include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. A pressure-sensitive adhesive sheet using a type pressure-sensitive adhesive is widely used. Examples of solvent-type adhesives include those containing acrylic resin as a main component. Such an acrylic resin is obtained by a technique called solution polymerization, in which an acrylic monomer is dissolved in a solvent and a polymerization reaction is carried out in the solvent. In solution polymerization, as the polymerization progresses, the molecular weight of the polymer increases and the viscosity of the reaction solution increases. There is Therefore, in order to ensure the cohesive force necessary for the adhesive, a cross-linking agent capable of reacting with an acrylic resin, such as an isocyanate-based compound or an epoxide-based compound, is added to the adhesive composition. Such a cross-linking agent builds a cross-linked network by reacting with the acrylic resin over time, and increases the cohesive strength of the pressure-sensitive adhesive layer.

In addition, as a method of forming a pressure-sensitive adhesive sheet for optical members, heat (or active energy ray)
In some cases, a method of curing by two-stage curing in which polymerization is performed by an active energy ray (or heat) after cross-linking by using is used. Since such a pressure-sensitive adhesive sheet is formed from, for example, a pressure-sensitive adhesive composition having both thermosetting and active energy ray-curing properties (hereinafter also referred to as a “dual-curable pressure-sensitive adhesive composition”), the thermosetting and has active energy ray curability. For this reason, before lamination with the adherend, for example, by performing only heat curing, it is possible to express hardness to the extent that it is easy to handle. It can be firmly adhered to the adherend by curing with lines (referred to as post-curing or after-curing).

For example, Patent Document 1 discloses a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is in a semi-cured state, wherein the pressure-sensitive adhesive composition contains a crosslinkable acrylic polymer, a cross-linking agent, and a reactive double bond in the molecule. and a photopolymerization initiator, and a pressure-sensitive adhesive sheet having a predetermined probe tack value and the like when the pressure-sensitive adhesive layer is post-cured. Such a pressure-sensitive adhesive sheet has excellent workability and excellent high-temperature and high-humidity durability.

Japanese Patent Application Laid-Open No. 2020-7407

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

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 with a release sheet and a laminate containing the pressure-sensitive adhesive sheet, and a method for producing a laminate. for the purpose.

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, found that the above object can be achieved by configuring the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer with specific components. I have perfected my invention.

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of a 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. containing an initiator (D),
The crosslinkable acrylic copolymer (A) is a non-crosslinkable (meth) acrylic acid ester unit (a1
) and a structural unit (a2) having an acidic functional group,
The non-crosslinkable (meth)acrylate unit (a1) includes a (meth)acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and a (meth)acrylate having an alkyl group having 3 or more carbon atoms. containing acrylic acid alkyl ester,
The content of the structural unit (a2) is 5 to 15% by mass with respect to the total structural units contained in the crosslinkable acrylic copolymer (A),
The polyfunctional monomer (C) is 1 to 2 per 100 mass of the crosslinkable acrylic copolymer (A)
An adhesive sheet containing 0 parts by mass.
Item 2
The adhesive layer has a gel fraction of 50 to 80%, and
Item 2. The pressure-sensitive adhesive sheet according to Item 1, wherein the pressure-sensitive adhesive layer has a gel fraction of 75 to 90% when post-cured by irradiating the pressure-sensitive adhesive layer with an active energy ray so that the cumulative amount of light is 3000 mJ/cm ² .
Item 3
The pressure-sensitive adhesive layer has an adhesive strength of 5 N/25 mm or more, and
Item 3. The pressure-sensitive adhesive sheet according to Item 1 or 2, wherein the pressure-sensitive adhesive layer has an adhesive strength of 10 N/25 mm or more when the pressure-sensitive adhesive layer is irradiated with an active energy ray so that the cumulative light amount is 3000 mJ/cm ² and post-cured.
Item 4
A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different peel strengths on both sides of the pressure-sensitive adhesive sheet according to any one of Items 1 to 3.
Item 5
Items 1 to 3, and an adherend provided on at least one side of the adhesive sheet,
The laminate, wherein the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state.
Item 6
Item 6. The laminate according to item 5, wherein the adherend is one or more selected from the group consisting of a resin plate and a resin film.
Item 7
A step 1 of laminating an adherend on at least one side of the pressure-sensitive adhesive sheet according to any one of Items 1 to 3, and
A method for producing a laminate, comprising a step 2 of post-curing the adhesive layer of the adhesive sheet by irradiating the adhesive layer with an active energy ray.
Item 8
8. The method for manufacturing a laminate according to claim 7, further comprising the step of processing the laminate after said step 2.
Item 9
Item 9. 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.

ADVANTAGE OF THE INVENTION The adhesive sheet which concerns on this invention has high adhesive force, and is excellent in blister resistance. Therefore, the pressure-sensitive adhesive sheet according to the present invention is less likely to lift or peel from the adherend even in a high-temperature and high-humidity environment, and is excellent in adhesion and durability.

It is a schematic diagram showing the cross section of the adhesive sheet of this invention which has a peeling sheet or a base material. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic showing the cross section of an example of the laminated body of this invention. It is the schematic showing the cross section of another example of the laminated body of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "contain" and "include" include "contain", "include", "substantially consist of" and "
including the concept of "consisting only of

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments. In the present specification, a numerical range represented by "-" means a range including the numerical values described before and after "-" as lower and upper limits.

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

Moreover, in this specification, "monomer" and "monomer" are synonymous, and "polymer" and "polymer" are synonymous.

1. Adhesive Sheet The adhesive sheet of the present invention comprises an adhesive layer containing a semi-cured 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. and an initiator (D).

In the adhesive sheet of the present invention, the crosslinkable acrylic copolymer (A) is a copolymer containing a non-crosslinkable (meth)acrylate unit (a1) and a structural unit (a2) having an acidic functional group. and 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. Contains (meth)acrylic acid alkyl esters. The structural unit (a2)
The content ratio is 5 to 1 with respect to all structural units contained in the crosslinkable acrylic copolymer (A)
5% by mass, and the polyfunctional monomer (C) is the crosslinkable acrylic copolymer (A) 100
1 to 20 parts by mass are contained per mass.

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, the pressure-sensitive adhesive sheet has high adhesive strength and excellent blister resistance. Conventionally, from the viewpoint of weight reduction and impact resistance improvement, resin plates such as polycarbonate and polymethyl methacrylate are sometimes used in applications such as display devices. In a humid environment, the pressure-sensitive adhesive layer is susceptible to blistering, i.e., blistering resistance. However, the pressure-sensitive adhesive sheet according to the present invention is more resistant to blistering than conventional ones, is less likely to lift or peel from adherends even in high-temperature and high-humidity environments, and has excellent adhesion and durability.

The pressure-sensitive adhesive composition is a raw material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, particularly
It is the dual-curing pressure-sensitive adhesive composition. As described above, the pressure-sensitive adhesive composition comprises, as constituent components, at least a crosslinkable acrylic copolymer (A), a crosslinker (B), and a polyfunctional monomer having two or more polymerizable double bonds in the molecule. It contains a polymer (C) and a photopolymerization initiator (D).

(Crosslinkable acrylic copolymer (A))
The crosslinkable acrylic copolymer (A) is a polymer formed of (meth)acrylic structural units, and has at least a non-crosslinkable (meth)acrylate unit (a1) and an acidic functional group. It is a copolymer containing units (a2). In the present specification, the “unit” or “structural unit” in the (meth)acrylic structural unit is a repeating unit (
(also referred to as a monomer unit).

The non-crosslinkable (meth)acrylic acid ester unit (a1) is a repeating unit derived from a (meth)acrylic acid alkyl ester and contains at least two or more structural units. In particular, the non-crosslinkable (meth)acrylate unit (a1) has 2 carbon atoms in the alkyl group.
It includes (meth)acrylic acid alkyl ester units below and (meth)acrylic acid alkyl ester units in which the alkyl group has 3 or more carbon atoms.

A (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 an alkyl group having 2 or less carbon atoms. The alkyl group here refers to the alkyl group of the alkyl ester moiety of the (meth)acrylic acid alkyl ester, and may be linear or branched.

Examples of (meth)acrylic acid alkyl esters in which the number of carbon atoms in the alkyl group is 2 or less include (
Examples include methyl methacrylate and ethyl (meth)acrylate. These may be used individually by 1 type, and may use 2 or more types together. The (meth)acrylic acid alkyl ester whose alkyl group has 2 or less carbon atoms is preferably methyl (meth)acrylate and/or ethyl (meth)acrylate.

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

Examples of (meth)acrylic acid alkyl esters in which the alkyl group has 3 or more carbon atoms include (
meth)propyl acrylate, isopropyl (meth)acrylate, n-(meth)acrylate
Butyl, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid n-octyl, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-(meth)acrylate Undecyl, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylate
and benzyl acrylate. These may be used individually by 1 type, and may use 2 or more types together.

In (meth)acrylic acid alkyl esters in which the number of carbon atoms in the alkyl group is 3 or more, the number of carbon atoms in the alkyl group is preferably 4 or more, and the number of carbon atoms in the alkyl group is preferably 18 or less. It is more preferably 8 or less.

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

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

For example, even after the adhesive layer is post-cured, the cohesive force of the polymer component is likely to increase, foaming is likely to be suppressed, and the blister resistance performance of the adhesive sheet is likely to be improved. , can be done as follows: That is, the number of carbon atoms in the alkyl group is is 3 or more (meth)acrylic acid alkyl ester is preferably 40 mass% or more,
It is more preferably 45% by mass or more, further preferably 50% by mass or more, particularly preferably 54% by mass or more, and preferably 95% by mass or less, preferably 90% by mass or less. is more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

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. (Meth)acrylic acid ester units other than acid alkyl ester units can be included. 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 only of acrylic acid alkyl ester units.

Although it is only a note just in case, 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, a structural unit having no acidic functional group, particularly a structural unit having no carboxy group.

In the structural unit (a2) having an acidic functional group, the acidic functional group is an acidic functional group that allows a cross-linking reaction to proceed with a cross-linking agent (B) described later. Examples of such an acidic functional group include a carboxy group, a group derived from a carboxy group, a sulfo group, a group derived from a sulfo group, etc. Among them, 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 a carboxy group-containing monomer. In this case, the pressure-sensitive adhesive sheet tends to have higher adhesive strength, and the durability tends to be particularly improved, so that the blister resistance becomes more excellent. Carboxy group-containing monomers include acrylic acid and methacrylic acid. These may be used individually by 1 type, and may use 2 or more types together.

The content of the structural unit (a2) is, as described above, 5 to 15% by mass based on the total structural units contained in the crosslinkable acrylic copolymer (A). As a result, the pressure-sensitive adhesive sheet tends to have higher adhesive strength, and also tends to improve durability. More preferably, the content of the structural unit (a2) is 5 to 10% by mass based on the total structural units contained in the crosslinkable acrylic copolymer (A).

Crosslinkable acrylic copolymer (A) is a non-crosslinkable (meth) acrylic acid ester unit (a1)
And in addition to the structural unit (a2) having an acidic functional group, other structural units may also be included. Examples of other structural units include a wide range of structural units derived from monomers copolymerizable with acrylic monomers, specifically (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl pyrrolidone, vinylpyridine and the like. Other structural units may include monomers having crosslinkable functional groups other than acidic functional groups. A hydroxyl group, an amino group, an amide group, a glycidyl group, or an isocyanate group can be mentioned as the crosslinkable functional group other than the acidic functional group.

Crosslinkable acrylic copolymer (A) is a non-crosslinkable (meth) acrylic acid ester unit (a1)
and a copolymer consisting only of the structural unit (a2) having an acidic functional group. Crosslinkable acrylic copolymer (A) is usually a random copolymer.

The glass transition temperature (Tg) of the crosslinkable acrylic copolymer (A) is not particularly limited. The glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to the point that the cohesive force of the polymer component increases in the adhesive layer, foaming is easily suppressed, and the blister resistance performance of the 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),
-35°C or higher is more preferable. The glass transition temperature of the crosslinkable acrylic copolymer (A) is preferably less than -20°C, more preferably -25°C or less.

The method for adjusting the glass transition temperature of the crosslinkable acrylic copolymer (A) is not particularly limited. A method of adjusting the content ratio of the (meth)acrylic acid alkyl ester unit of 3 or more and the structural unit (a2) having an acidic functional group may be mentioned.

In the present invention, 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 monomers used in the synthesis of the copolymer.
Fox's formula: 1/Tg=(W1/Tg1)+(W2/Tg2)+...+(Wm/Tgm
)
where W1+W2+...+Wm=1
In the formula, Tg is the glass transition temperature (unit: K) of the crosslinkable acrylic copolymer (A), and Tg
1, Tg2, .・・・
Wm is the mass fraction of each structural unit in the crosslinkable acrylic copolymer (A). In addition, Tg
1 and W1 have a corresponding relationship, that is, the monomer constituting the homopolymer exhibiting the glass transition temperature of Tg1 is the same as the monomer for forming the structural unit having a mass fraction of W1. Similarly, Tg2 and W2, . . . Tgm and Wm are in a corresponding relationship.

As the glass transition temperature of the homopolymer, for example, Polymer Handb
cook 4th Edition (Wiley-Interscience 2003
) can be used. If not stated in such handbook, for example:
A differential scanning calorimeter (DSC) can measure the glass transition temperature of the homopolymer. DSC
As the measurement conditions, 5 mg of the sample, under a nitrogen atmosphere, the first measurement (1st RUN)
After raising the temperature from -100 ° C to 200 ° C at a temperature increase rate of 5 ° C / min, -1 at a temperature decrease rate of 5 ° C / min
Cool to 00 ° C., and -10 at a heating rate of 5 ° C./min in the second measurement (2nd RUN)
The temperature is raised from 0°C to 200°C. Here, the glass transition temperature is -1 in the 2nd RUN
In the region where the baseline of the DSC curve measured when the temperature is raised from 00 ° C. to 200 ° C. changes to the sigmoid shape in the endothermic direction, the extension line of the baseline on the lower temperature side than the region where it changes to the sigmoid shape Refers to the intersection of the tangents at the point of inflection.

The weight average molecular weight of the crosslinkable acrylic copolymer (A) is preferably 200,000 to 2,000,000.
00,000 to 1,500,000 is more preferable. When the weight-average molecular weight is within the above range, the pressure-sensitive adhesive layer can be easily maintained in a semi-cured state, can easily exhibit hardness after post-curing, and is excellent in workability. The weight-average molecular weight of the crosslinkable acrylic copolymer (A) is the value before crosslinking with a crosslinking agent. The weight average molecular weight is a value measured by size exclusion chromatography (SEC) and determined based on polystyrene standards. 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) is not particularly limited, and for example, a method similar to the method for producing a known acrylic copolymer can be adopted.

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

(Crosslinking agent B)
The cross-linking agent (B) can be used as long as the cross-linking reaction of the cross-linkable acrylic copolymer can
There is no particular limitation, and for example, a wide range of known cross-linking agents can be used. For example, a crosslinker (
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 difunctional or higher epoxy compound.

Examples of epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether,
polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidylxylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like.

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected according to the desired adhesiveness, etc.
0.01 to 5 parts by mass is preferable with respect to 100 parts by mass of the crosslinkable acrylic copolymer (A), 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 workability can be further enhanced. The cross-linking agent (B) may be used alone or in combination of two or more. When two or more are used in combination, the total mass is preferably within the above range.

(Polyfunctional monomer (C))
A 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, when the pressure-sensitive adhesive layer in a semi-cured state is post-cured, the radical polymerization reaction of the polyfunctional monomer (C), particularly A cross-linking reaction progresses, whereby the pressure-sensitive adhesive layer is post-cured and becomes a post-cured state.

Polyfunctional monomer (C), for example, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, di(meth)acrylic acid 1,4-butylene glycol, di(meth)acrylic acid 1,9-
Nonanediol, 1,6-hexanediol diacrylate, polybutylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene di(meth)acrylate Glycol, polypropylene glycol di(meth)acrylate, diacrylate of bisphenol A diglycidyl ether, tri(meth)acrylate trimethylolpropane, tri(meth)acrylate pentaerythritol, tetra(meth)acrylate pentaerythritol, etc. Examples include (meth)acrylic acid esters of alcohols, vinyl methacrylate, and the like. These may be used individually by 1 type, or may use 2 or more types together.

The number of polymerizable double bonds in the polyfunctional monomer (C) is 2 or more, preferably 2 or more and less than 5, more preferably 2 or more and less than 4.

A commercial item can be used for a polyfunctional monomer (C), for example. Commercially available products include trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) and trifunctional monomer M321 (trimethylolpropane propylene oxide-modified triacrylate) manufactured by Toagosei Co., Ltd., and bifunctional monomer M211B (bisphenol 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 more effectively increased, and the workability of the pressure-sensitive adhesive sheet can be easily improved. Examples of such a polyfunctional monomer (C) include bisphenol A diglycidyl ether diacrylate, propoxylated bisphenol A diacrylate, bisphenol F diglycidyl ether diacrylate, and the like.

The glass transition temperature (Tg) of the homopolymer of the polyfunctional monomer (C) is preferably 30° C. or higher, more preferably 50° C. or higher. The glass transition temperature (Tg) when the polyfunctional monomer is a homopolymer may be, for example, 300° C. or lower. By setting the glass transition temperature (Tg) of the polyfunctional monomer C as a homopolymer within the above range, the processability of the pressure-sensitive adhesive sheet can be more effectively enhanced. For the glass transition temperature, the literature value may be adopted, but after making the polyfunctional monomer (C) a homopolymer having a weight average molecular weight of 10,000 or more, the glass transition temperature of the homopolymer is measured by DSC (differential A value measured using a scanning calorimeter) can be adopted.

In the pressure-sensitive adhesive composition, the polyfunctional monomer (C) is a crosslinkable acrylic copolymer (A) 100
1 to 20 parts by mass are contained per mass. As a result, shrinkage on curing of the adhesive layer in a post-cured state due to the post-curing treatment is less likely to occur, and as a result, the adhesive strength of the adhesive sheet is improved and the blister resistance is excellent. In particular, the crosslinkable acrylic copolymer (A) has a higher Tg than conventional ones and a strong cohesive force of the polymer component, so curing shrinkage is likely to occur. However, in the present invention, on the other hand, by including a specific amount of the polyfunctional monomer (C), such cure shrinkage is less likely to occur. As a result, the adhesive sheet can have excellent blister resistance while maintaining high adhesive strength.

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

(Photoinitiator (D))
The adhesive composition contains a photopolymerization initiator (D). The photopolymerization initiator is preferably one that initiates polymerization of the crosslinkable acrylic copolymer and the polyfunctional monomer upon exposure to active energy rays in the post-curing treatment. A well-known photoinitiator can be used as a photoinitiator (D). The term "active energy ray" means an electromagnetic wave or charged particle beam that has an energy quantum, and includes ultraviolet rays, electron beams, visible rays, X-rays, ion beams, and the like. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

Examples of the photopolymerization initiator (D) include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, amine-based initiators, and acylphosphine oxide-based initiators. agents and the like.

Specific examples of acetophenone-based initiators include diethoxyacetophenone and benzyldimethylketal. Specific examples of benzoin ether-based initiators include benzoin and benzoin methyl ether. Specific examples of benzophenone-based initiators include benzophenone and methyl o-benzoylbenzoate.

Specific examples of hydroxyalkylphenone-based initiators include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by IGM Resins B.V., Omnirad 184
(commercially available as Specific examples of thioxanthone-based initiators include 2-isopropylthioxanthone and 2,4-dimethylthioxanthone. Specific examples of amine-based initiators include triethanolamine and ethyl 4-dimethylbenzoate. Specific examples of acylphosphine oxide initiators include phenylbis(2,4,6-
Trimethylbenzoyl)phosphine oxide (IGM Resins B.V., O
(commercially available as mnirad819).

Other photopolymerization initiators (D) include, for example, 2,2-dimethoxy-2-phenylacetophenone, 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-
alkylphenone-based photopolymerization initiators such as methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-propanone; Acylphosphine oxide polymerization initiators such as 4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl)phenylphosphine oxide, intramolecular hydrogen abstraction such as methyl benzoylformate and 4-methylbenzophenone In addition to type photopolymerization initiators, oxime ester photopolymerization initiators, cationic photopolymerization initiators, and the like can be used.

The content of the photopolymerization initiator (D) in the adhesive composition is the crosslinkable acrylic copolymer (A) 10
It is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 0 part by mass. Within the above range, the desired hardness can be adjusted by post-curing, and the molecular weight after post-curing can be adjusted to an appropriate range, so that a pressure-sensitive adhesive sheet with excellent workability can be obtained. As the photopolymerization initiator (D), one type may be used alone or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

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

When the pressure-sensitive adhesive composition contains a solvent, its content is not particularly limited, for example, it can be 25 to 500 parts by mass with respect to 100 parts by mass of the crosslinkable acrylic copolymer (A), and 30 to 4 parts by mass.
00 parts by mass is more preferable. Also, the content of the solvent is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, relative to 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. When two or more types are used in combination, the total mass is preferably within the above range.

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

The pressure-sensitive adhesive composition can contain various additives for pressure-sensitive adhesives within a range that does not impair the effects of the present invention. 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. Dyes and pigments may also be added for the purpose of coloring.

Plasticizers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate,
Carboxylate vinyl esters such as vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl benzoate, and styrene.

Examples of antioxidants include phenol antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. These antioxidants are 1
One type 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 its compatibility with the adhesive and its high effect.

Examples of tackifiers include rosin-based resins, terpene-based resins, terpene-phenol-based resins, coumarone-indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, and petroleum resins.

Silane coupling agents include, for example, mercaptoalkoxysilane compounds (eg, mercapto group-substituted alkoxy oligomers, etc.).

Examples of ultraviolet absorbers include benzotriazole-based compounds and benzophenone-based compounds. However, when ultraviolet rays are used as the active energy rays for 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 is not particularly limited. For example, a crosslinkable acrylic copolymer (A)
and a cross-linking agent (B), and a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule,
The pressure-sensitive adhesive composition can be prepared by mixing the photopolymerization initiator (D) and, if necessary, a solvent and other components in a predetermined mixing ratio.

(Adhesive layer)
The pressure-sensitive adhesive layer is formed by semi-curing the pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer contains a semi-cured product of the pressure-sensitive adhesive composition and has post-curing properties.

The pressure-sensitive adhesive layer can be formed of only the semi-cured pressure-sensitive adhesive composition, or the pressure-sensitive adhesive layer can contain other than the semi-cured pressure-sensitive adhesive composition as long as the effects of the present invention are not hindered. .

In the present invention, the adhesive layer before irradiation is considered to be in a semi-cured state when the gel fraction of the adhesive layer increases by 10% by mass or more compared to before irradiation by irradiation with active energy rays. Irradiation of active energy rays in this case is performed as follows. First, optical transparent PET separators are pasted on both sides of the pressure-sensitive adhesive layer. Then, an active energy ray (high-pressure mercury lamp or metal halide lamp) is emitted from one optical transparent PET separator side with an integrated light amount of 3000 mJ /
cm ² shall be irradiated. By measuring the gel fraction of the pressure-sensitive adhesive layer formed by this irradiation and examining whether it increased by 10% by mass or more before and after irradiation, it is determined 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 the adhesive sheet (adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and shaken for 24 hours.
Thereafter, the contents of the sample bottle are filtered through a 150-mesh stainless wire mesh, and the residue on the wire mesh is dried at 100° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the following formula 1
Gel fraction (% by mass) = (dry mass/collected mass of pressure-sensitive adhesive layer) x 100 Equation 1
The gel fraction can be obtained by

In the present invention, the "semi-cured state" is preferably a state after heat curing of the pressure-sensitive adhesive composition. In addition, it is preferable to perform "post-curing" by irradiating an active energy ray after this heat treatment. 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 pressure-sensitive adhesive layer has a gel fraction of 50 to 80%, and the pressure-sensitive adhesive layer was post-cured by irradiating active energy rays so that the integrated light amount was 3000 mJ/cm ² . The gel fraction in the case is preferably 75-90%. In this case, it is possible to increase the cohesion of the polymer in the adhesive layer in the post-cured state while maintaining the adhesion even in the post-cured state, and as a result, the adhesive layer can be maintained even in a high-temperature and high-humidity environment. Foaming can be suppressed. As a reminder, the gel fraction of the pressure-sensitive adhesive layer of 50 to 80% means that the pressure-sensitive adhesive layer in a semi-cured state has a gel fraction of 50 to 80%. The gel fraction of such an adhesive layer is more preferably 60-80%, more preferably 65-80%. Moreover, when measuring the gel fraction after irradiating and hardening an active energy ray to an adhesive layer, irradiation of an active energy ray is performed as follows. First, optical transparent PET separators are pasted on both sides of the pressure-sensitive adhesive layer. Then, an active energy ray (a high-pressure mercury lamp or a metal halide lamp) is irradiated from one optical transparent PET separator side 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 of the pressure-sensitive adhesive layer and the gel fraction after post-curing is preferably 5% or more and 20% or less from the viewpoint of easily suppressing curing shrinkage. is preferably

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the application, and is not particularly limited. For example, the thickness of the adhesive layer is preferably 5 to 150 μm, more preferably 8 to 100 μm, even more preferably 10 to 80 μm, particularly preferably 10 to 40 μm. By setting the thickness of the pressure-sensitive adhesive layer within each of the ranges described above, it is possible to suppress the protrusion and stickiness of the pressure-sensitive adhesive, thereby enhancing workability. Furthermore, by setting the thickness of the pressure-sensitive adhesive layer within the above range, the production of the pressure-sensitive adhesive sheet is facilitated.

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer has an adhesive strength of 5 N/25 mm or more, and
It is preferable that the pressure-sensitive adhesive layer has an adhesive strength of 10 N/25 mm or more when post-cured by irradiating the pressure-sensitive adhesive layer with an active energy ray so that the integrated light quantity becomes 3000 mJ/cm ² . This will
Even after the pressure-sensitive adhesive layer is post-cured, it can have excellent adhesion to the substrate. Also in this case, the adhesive strength of 5 N/25 mm or more means that the adhesive strength of the adhesive layer in a semi-cured state is 5 N/
25 mm. In addition, when measuring the adhesive strength after curing by irradiating the adhesive layer with an active energy ray, the irradiation conditions for the active energy ray are the same as those for measuring the post-cured gel fraction described above. be.

The adhesive strength of the adhesive layer and the adhesive strength after post-curing of the adhesive layer strongly depend on the composition of the adhesive composition. By forming a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition in which the type and the content of the polyfunctional monomer (C) are adjusted to a predetermined range, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer It is possible to obtain a desired level of adhesion after post-curing.

Adhesive strength is a value measured by the following method. A second release sheet, which is a light separator film described later, is peeled off from the pressure-sensitive adhesive layer, attached to a PET film having a thickness of 50 μm, and cut to a width of 25 mm. After cleaning the non-tin surface of the float glass with ethanol, the first release sheet, which is the heavy separator film described later, is peeled off from the adhesive sheet, and the adhesive surface of the adhesive sheet is adhered to the glass by reciprocating a 2 kg roller. After autoclave treatment (40° C., 0.5 MPa, 30 min) of the obtained PET/adhesive layer/glass sample, the other end of the sample was peeled off in the peeling direction of 180 degrees at a speed of 300 mm/min. , 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 adhesive layer in a semi-cured state). on the other hand,
A sample with the same PET/adhesive layer/glass configuration as above was autoclaved (40 ° C.
, 0.5 MPa, 30 min), and then ultraviolet rays from the PET film side with an integrated light amount of 3
A test sample is obtained by irradiating 000 mJ/cm ² . In this test sample, the other end of the adhesive sheet was peeled at a speed of 300 mm / min in the peeling direction of 180 degrees, and the adhesive force to glass at that time was post-cured (that is, after post-curing of the adhesive layer (in the post-cured state).

(adhesive sheet)
The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer containing a semi-cured product of the pressure-sensitive adhesive composition, as described above. Therefore, the pressure-sensitive adhesive sheet of the present invention has post-curing properties, particularly active energy ray-curing properties.

The configuration of the pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it has the pressure-sensitive adhesive layer.
It can have the same configuration as a known adhesive sheet. The pressure-sensitive adhesive sheet can be a single-layer pressure-sensitive adhesive sheet composed only of the pressure-sensitive adhesive layer. Alternatively, the pressure-sensitive adhesive sheet can be a single-sided pressure-sensitive adhesive sheet having a substrate (preferably a transparent substrate) on one side, or a double-sided pressure-sensitive adhesive sheet.

Specific examples of the adhesive sheet include a single-layer adhesive sheet consisting of an adhesive layer, a multilayer adhesive sheet having a plurality of laminated adhesive layers, and a multilayer adhesive sheet having another adhesive layer laminated between adhesive layers. multi-layer pressure-sensitive adhesive sheet in which a support is laminated between pressure-sensitive adhesive layers, and a multi-layer pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one side of a support and another pressure-sensitive adhesive layer is laminated on the other side An adhesive sheet is 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 common film used in the optical field can be used like the transparent substrate. Since such a pressure-sensitive adhesive sheet is also excellent in transparency as a whole pressure-sensitive adhesive sheet, 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 may be provided with a transparent substrate 12a on one side thereof. In this case, the other surface of the adhesive layer 11 is preferably covered with a release sheet 12b. When an adhesive sheet is used, the release sheet 12b is peeled off, and the adhesive layer 11 is adhered to the desired adherend so that the adhesive layer 11 is adhered to the desired adherend. preferable. As the transparent substrate, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, and 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. Furthermore, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, or an ultraviolet absorption layer may be provided on the opposite side of the transparent substrate from the pressure-sensitive adhesive layer.

The present invention includes a pressure-sensitive adhesive sheet with a release sheet provided with release sheets on both sides of the pressure-sensitive adhesive sheet. Such a pressure-sensitive adhesive sheet with a release sheet can be provided with a pair of release sheets having different peel strengths on both sides of the pressure-sensitive adhesive sheet. For example, as shown in FIG. and 12b.

As the release sheet, a release 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. is mentioned.

Papers and polymer films are used as the base material for the release sheet in the release 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 compound containing a long-chain alkyl group is used. In particular, an addition-type silicone-based release agent having high reactivity is preferably used.

Specifically, as the silicone-based release agent, B
Y24-4527, SD-7220, etc., and KS-3600 and KS-7 manufactured by Shin-Etsu Chemical Co., Ltd.
74, X62-2600 and the like. In addition, the silicone release agent may contain a silicone resin which is an organic silicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ ═CH(CH ₃ ) SiO _1/2 units. preferable. Specific examples of silicone resins include BY24-843, SD-, manufactured by Dow Corning Toray Silicone Co., Ltd.
7292, SHR-1404, etc., and KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Co., Ltd.
etc.

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

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it preferably has a pair of release sheets having different peel strengths. That is, it is preferable that the release sheet 12a and the release sheet 12b have different releasability so that they can be easily separated. When the releasability from one side and the releasability from the other are different, it becomes easy to peel off only the release sheet with higher releasability first. In that case, the releasability of the release sheets 12a and 12b may be adjusted according to the bonding method and the bonding order.

The present invention may also relate to a pressure-sensitive adhesive sheet with a transparent film provided on at least one surface of the pressure-sensitive adhesive sheet. In this case, the transparent film is preferably at least one selected from polyethylene terephthalate film, acrylic film, polycarbonate film, triacetylcellulose film and cycloolefin polymer film. The adhesive sheet with a transparent film may be a sheet in which transparent film/adhesive sheet/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 wide variety of known pressure-sensitive adhesive sheet production methods can be employed. For example, by a production method including a step of applying the pressure-sensitive adhesive composition on a release sheet to form a coating film, and a step of heating the coating film to obtain a cured product in a semi-cured state (semi-cured product). , the pressure-sensitive adhesive sheet of the present invention can be produced. In this case, by heating the coating film, the reaction between the crosslinkable acrylic copolymer (A) and the crosslinker (B) proceeds to form a cured product in a semi-cured state (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 proceeds only slightly, the pressure-sensitive adhesive layer contains At least part of the polymerizable monomer (polyfunctional monomer (C), etc.) and the photopolymerization initiator (D) are 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 removing the solvent after coating. The aging treatment can be performed by standing at 23° C. for 7 days, for example.

Coating of the pressure-sensitive adhesive composition can be carried out using a known coating device. Coating devices include, for example, blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, micro gravure coaters, rod blade coaters, lip coaters, die coaters and curtain coaters.

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 pressure-sensitive adhesive sheet of the present invention is also not particularly limited, and it can be used in various ways depending on the application, purpose, and the like. 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 adhesive layer of the adhesive sheet is in a semi-cured state, it is preferably bonded to an adherend and irradiated with active energy rays to post-cure the adhesive layer.
Since the pressure-sensitive adhesive sheet of the present invention is a two-stage curing pressure-sensitive adhesive sheet, it has a pressure-sensitive adhesive layer that is semi-cured only by heat before lamination, and the pressure-sensitive adhesive layer is post-cured by active energy rays after lamination. Because of its properties, it can be used in a variety of ways that suit its properties. The adherend is the same as the adherend in the laminate described later.

Since the pressure-sensitive adhesive sheet of the present invention has high adhesive strength and excellent blistering resistance, it is less likely to lift or peel from the adherend even in a high-temperature and high-humidity environment, and has excellent adhesion and durability. Therefore, even when the pressure-sensitive adhesive sheet of the present invention is used for applications such as laminating optical members having a large screen, wrinkles are less likely to occur and workability is excellent.

In addition, the adhesive sheet of the present invention is less sticky on the end surface after post-curing, and can prevent, for example, adhesion of the adhesive to the punching blade during punching and deformation of the adhesive layer associated therewith. Furthermore, the pressure-sensitive adhesive sheet of the present invention does not cause deformation, protrusion, peeling, etc. of the pressure-sensitive adhesive layer when it is punched to a desired size after post-curing and then cut for the purpose of arranging the end face, and has good workability. Are better.

The pressure-sensitive adhesive sheet of the present invention is adhered to an adherend such as a substrate, post-cured, and has excellent substrate adhesion and durability even when exposed to a high-temperature and high-humidity environment. Therefore, it is possible to suppress the occurrence of floating and peeling. For example, the pressure-sensitive adhesive sheet of the present invention is laminated to a polycarbonate substrate, post-cured, and then, even when exposed to a high-temperature and high-humidity environment, the adhesive sheet floats from the polycarbonate substrate,
Peeling can be suppressed.

In this specification, the durability of the pressure-sensitive 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. Then, the pressure-sensitive adhesive layer is post-cured. After that, the pressure-sensitive adhesive sheet is allowed to stand under an environment of 85° C. and a relative humidity of 85% for 240 hours. After that, the pressure-sensitive adhesive sheet is observed, and if the pressure-sensitive adhesive sheet is prevented from floating or peeling off from the polycarbonate plate and/or the triacetylcellulose film, it can be judged to be excellent in durability.

As described above, the pressure-sensitive adhesive sheet of the present invention is an optical member that requires durability, and is preferably used for lamination of an optical member that requires molding after lamination with an optical member. The pressure-sensitive adhesive sheet of the present invention can also be used by bonding it to an optical member such as a polarizing plate. A polarizing plate includes a polarizer and a polarizer protective film. The pressure-sensitive adhesive sheet of the present invention is preferably attached to a polarizer protective film. As the polarizer protective film, a wide range of resin films can be used. resin film, polycarbonate resin film, acrylic resin film, polypropylene resin film and the like.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it can be used for bonding two adherends. Examples of the adhesive sheet of the present invention when used for bonding two adherends include bonding of transparent optical films inside a touch panel, bonding of a transparent optical film and glass, and transparent optical use of a touch panel. Examples include lamination of a film and a liquid crystal panel, lamination of a cover panel and a transparent optical film, lamination of a cover panel and a transparent optical film, and the like, particularly when any member is a polycarbonate base material. useful for As the transparent optical film, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, and cycloolefin polymer film can be used. Further, a hard coat layer may be provided on the transparent optical film or the polycarbonate substrate. The cover panel includes resin and glass.

2. Laminate The present invention includes a laminate comprising the adhesive sheet and adherend described above. Such laminates are
It has the pressure-sensitive adhesive sheet of the present invention and an adherend provided on at least one side of the pressure-sensitive adhesive sheet. In the laminate, 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 laminate of the present invention, the adhesive layer of the adhesive sheet is in a post-cured state by irradiation with active energy rays. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, a laminate is formed by irradiating active energy rays in a state in which two adherends are laminated with a semi-cured pressure-sensitive adhesive sheet to post-cure the pressure-sensitive adhesive layer. preferably. Here, at least one of the adherends may be a base material, an optical member, or the like, and more specifically, a resin plate, a resin film, glass, or the like, and other known polarizing plates or the like are also exemplified. be. The adherend may have a single-layer structure,
A laminated structure formed by laminating different kinds of materials may be used.

At least one adherend in the laminate is particularly preferably a resin plate. Examples of the resin film include known transparent films. When adherends are laminated on both sides of the pressure-sensitive adhesive sheet, the adherends may be of the same type or of different types.

In this 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 laminate of the present invention, since the thickness of the adherend is not particularly limited, for example, a resin plate having a thickness of 250 μm or more can be applied as the adherend, or a resin plate having a thickness of less than 250 μm can be used as the adherend. Films can also be applied.

The type of resin plate is not particularly limited, and for example, substrates formed of known resins can be widely used. Examples include polycarbonate (PC) plates and polymethacrylate (PMMA) plates.
In addition to plates, etc., Mitsubishi Gas Chemical "Iupilon MR58", Kuraray "Paramighty MT3L"
TR" and Teijin's "Panlight PC1151". Further, the resin plate may have a laminated structure formed of different materials, and may have, for example, a PMMA/PC two-kind two-layer structure or a two-kind three-layer structure PMMA/PC/PMMA. . The resin plate may have a known hard coat layer.

FIG. 2 is a schematic diagram showing a cross section of an example of the laminate of the present invention. FIG. 2 is a cross-sectional view showing an example of the structure of a laminate 20 in which the pressure-sensitive adhesive sheet 21 of the present invention is adhered to a substrate 22 and an optical member 24. As shown in FIG. As shown in FIG. 2, the pressure-sensitive adhesive sheet 21 of the present invention is preferably used for bonding to the substrate 22, and may be used for bonding the substrate 22 and another optical member 24. preferable. In addition, the adhesive sheet 21 of the present invention may be used for lamination with a polarizing plate.

In the laminate, when at least one adherend is an optical member, the optical member includes:
Examples thereof include a shatterproof film bonded to each constituent member of an optical product such as a touch panel or an image display device or a cover lens of the outermost layer. 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, and an ITO film on the surface of a glass plate.
ITO glass provided with a TO film, a transparent conductive film obtained by coating a transparent resin film with a conductive polymer, a hard coat film, an anti-fingerprint film, and the like. Examples of constituent members of the image display device include antireflection films, oriented films, polarizing films, retardation films, brightness enhancement films and the like used in liquid crystal display devices. Materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetylcellulose, polyimide, and cellulose acylate.

FIG. 3 is a schematic diagram showing a cross section of another example of the laminate of the present invention. As shown in FIG. 3, the adherend may have steps (27a, 27b, 27c, 27d). In FIG. 3, the substrate has stepped portions (27a, 27b), and the optical member has stepped portions (27c, 27d).
)have. The thickness of the stepped portions (27a, 27b, 27c, 27d) is usually 5 to
60 μm. As described above, the pressure-sensitive adhesive sheet 21 of the present invention can be adhered to a member having a stepped portion, and can follow unevenness caused by the stepped portion.

A method for manufacturing the laminate is not particularly limited. For example, a step 1 of laminating an adherend on at least one 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 an active energy ray. 2 in this order, a laminate can be manufactured. Since the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state before being irradiated with an active energy ray, the initial adhesion to the substrate is good. By post-curing the adhesive layer with active energy rays after bonding the adhesive sheet to the adherend in this way, the cohesive force of the adhesive layer increases and the adhesiveness to the adherend improves. Further, the post-cured pressure-sensitive adhesive layer can prevent the substrate from being deformed or distorted.

In the present invention, active energy rays include ultraviolet rays, electron rays, visible rays, X-rays, ion rays, etc., and can be appropriately selected according to the photopolymerization initiator contained in the pressure-sensitive adhesive layer. Among them,
From the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

As the ultraviolet light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an extra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like can be used.

Electron beams emitted from various types of electron beam accelerators, such as Cockroftwald type, Van de Clough type, resonance transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type, are used as electron beams. can.

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

The method for manufacturing the laminate may further include a step of processing the laminate after step 2 above. In this step, for example, various processing can be performed on the laminate, and specific examples include punching, cutting, and the like. The processing method is not particularly limited, and for example, a wide range of known processing methods can be adopted.

EXAMPLES The present invention will be described in more detail below 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 produced by a polymerization reaction of polymerizable monomers. More specifically, the alkyl group has 3 or more carbon atoms (meta)
A butyl acrylate monomer (hereinafter, "BA") as an acrylic acid alkyl ester, a methyl acrylate monomer (hereinafter, "MA") as a (meth)acrylic acid alkyl ester having 2 or less carbon atoms in the alkyl group, and a carboxy group-containing Acrylic acid (hereinafter referred to as “AA”) was prepared as a monomer and mixed so as to have a mass ratio (70:22:8) shown in Table 1 to prepare a monomer mixture. This monomer mixture was dissolved in ethyl acetate and polymerized at 60° C. in the presence of AIBN (azobisisobutyronitrile) as a radical polymerization initiator. Thus, a crosslinkable acrylic copolymer (A-1) was obtained. In the resulting crosslinkable acrylic copolymer (A-1), the glass transition temperature (Tg
) was -33°C.

(Production Example 2: Synthesis of crosslinkable acrylic copolymer (A-2))
BA as a (meth)acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms,
An ethyl acrylate monomer (hereinafter referred to as "EA") as a (meth)acrylic acid alkyl ester having an alkyl group having 2 or less carbon atoms and an AA as a carboxy group-containing monomer were prepared, and the mass ratio shown in Table 1, respectively. A crosslinkable acrylic copolymer (A-2) was obtained in the same manner as in Production Example 1, except that the monomer mixture was prepared by mixing so that In the obtained crosslinkable acrylic copolymer (A-2), the glass transition temperature (Tg) obtained 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 an alkyl group having 3 or more carbon atoms,
Methyl methacrylate monomer (hereinafter referred to as "MMA") as a (meth)acrylic acid alkyl ester having an alkyl group having 2 or less carbon atoms, and AA as a carboxy group-containing monomer
were prepared, and a crosslinkable acrylic copolymer (A-3) was obtained in the same manner as in Production Example 1 except that a monomer mixture was prepared by mixing so that the mass ratios shown in Table 1 were obtained. . In the obtained crosslinkable acrylic copolymer (A-3), the glass transition temperature (T
g) was -25°C.

(Production Example 4: Synthesis of crosslinkable acrylic copolymer (A-4))
BA as a (meth)acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms,
Prepare MA as a (meth)acrylic acid alkyl ester having 2 or less carbon atoms in the alkyl group, and AA as a carboxy group-containing monomer, and mix so that the mass ratio shown in Table 1 is obtained. A crosslinkable acrylic copolymer (A-4) was obtained in the same manner as in Production Example 1, except that a mixture was prepared. In the resulting crosslinkable acrylic copolymer (A-2), FOX
The glass transition temperature (Tg) obtained using the formula was -26°C.

(Production Example 5: Synthesis of crosslinkable acrylic copolymer (a-1))
BA as a (meth)acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms,
MA and hydroxyethyl acrylate (hereinafter referred to as “HEA”) were prepared as (meth)acrylic acid alkyl esters having an alkyl group having 2 or less carbon atoms, and mixed so as to have a mass ratio shown in Table 1. A crosslinkable acrylic copolymer (a-1) was obtained in the same manner as in Production Example 1, except that a monomer mixture was prepared. Obtained crosslinkable acrylic copolymer (a-1)
, the glass transition temperature (Tg) obtained using the FOX formula was -39°C.

(Production Example 6: Synthesis of crosslinkable acrylic copolymer (a-2))
Prepare 2-ethylhexyl acrylate (hereinafter referred to as "2EHA") as a (meth)acrylic acid alkyl ester having 3 or more carbon atoms in the alkyl group, and AA as a carboxy group-containing monomer, which are shown in Table 1. A crosslinkable acrylic copolymer (a-2) was obtained in the same manner as in Production Example 1, except that the monomer mixture was prepared by mixing so as to achieve the indicated mass ratio. The resulting crosslinkable acrylic copolymer (a-2) had a glass transition temperature (Tg) of -60° C. as determined using the FOX formula.

(Production Example 7: Synthesis of crosslinkable acrylic copolymer (a-3))
BA as a (meth)acrylic acid alkyl ester having an alkyl group having 3 or more carbon atoms,
Prepare MA and MMA as (meth)acrylic acid alkyl esters in which the number of carbon atoms in the alkyl group is 2 or less, and AA as a carboxy group-containing monomer, and mix so that the mass ratio is shown in Table 1. A crosslinkable acrylic copolymer (a-3) was obtained in the same manner as in Production Example 1, except that a monomer mixture was prepared. The obtained crosslinkable acrylic copolymer (a-3) had a glass transition temperature (Tg) of -44° C. as determined using the FOX formula.

(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 compound as the crosslinker (B) (Mitsubishi Gas Chemical Co., Ltd., Tetrad X) 0.1 parts by mass (denoted as epoxy in Table 2), and ethylene oxide-modified diacrylate (Toagosei Co., Ltd., Aronix M211B, Tg = 75 ° C.) and 1-hydroxy-cyclohexyl-phenyl-ketone as a photopolymerization initiator (D) (manufactured by IGM Resins B.V., Omni
rad184) was mixed with 0.5 parts by mass, and 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 pressure-sensitive adhesive composition was applied onto a first release sheet (heavy separator film, manufactured by Teijin DuPont Films Ltd., a release-treated polyethylene terephthalate film). Coating is
A doctor blade type YD manufactured by Yoshimitsu Seiki Co., Ltd. was used to obtain a thickness of 15 μm after drying. Thereafter, the adhesive sheet was dried at 100° C. for 3 minutes in a hot air dryer to remove the solvent, thereby forming a pressure-sensitive adhesive sheet having a semi-cured pressure-sensitive adhesive layer.

On one side of this adhesive sheet, a second release sheet (light separator film, manufactured by Teijin DuPont Films Co., Ltd.), which has been subjected to a release treatment with higher release than the first release sheet, is pasted. I got a sticky 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) was changed to 5 parts by mass, and the photopolymerization initiator (D) was phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan, I
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 composition was changed to RGACURE819).

(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.) A product and an adhesive sheet with a release sheet were obtained.

(Example 6)
The crosslinkable acrylic copolymer (A) obtained in Production Example 2 as the crosslinkable acrylic copolymer (A)
-2), and the photopolymerization initiator (D) was changed to phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan, IRGACURE819) in the same manner as in Example 1. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained.

(Example 7)
The crosslinkable acrylic copolymer (A) obtained in Production Example 3 as the crosslinkable acrylic copolymer (A)
-3), and the photopolymerization initiator (D) was changed to phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan, IRGACURE819) in the same manner as in Example 1. A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained.

(Example 8)
The crosslinkable acrylic copolymer (A) obtained in Production Example 4 as the crosslinkable acrylic copolymer (A)
-4), the amount of the cross-linking agent (B) was changed to 0.05 parts by mass, and the photopolymerization initiator (D)
Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by BASF Japan, IRGACURE819) in the same manner as in Example 1 to obtain a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet. .

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

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

(Comparative Example 4)
The crosslinkable acrylic copolymer (a) obtained in Production Example 6 as the crosslinkable acrylic copolymer (A)
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 changing to -2).

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

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

The sample for measurement in the semi-cured state and the sample for measurement after post-curing (in Table 2, "
About 0.1 g of the pressure-sensitive adhesive sheet (described as "before curing" and "after curing") was collected in a sample bottle, added with 30 ml of ethyl acetate, and shaken for 24 hours. Thereafter, the contents of the sample bottle were filtered through a 150-mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the following formula 1
Gel fraction (% by 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 adhesive layer, was peeled off, and a 50 μm thick P
It was attached to an ET film and cut into 25 mm width. After cleaning the non-tin side of the float glass with ethanol, peel off the first release sheet, which is the heavy separator film of the adhesive sheet,
A 2-kg roller was reciprocated to bond the adhesive surface of the adhesive sheet to the glass. Obtained PET
/Adhesive layer/Glass configuration samples were autoclaved (40°C, 0.5 MPa, 3
0 min), the other end of this sample was peeled at a speed of 300 mm / min in the peeling direction of 180 degrees, and the adhesive strength to glass at that time (that is, the adhesive strength of the adhesive layer in the semi-cured state; Table 2
middle, before curing) was measured. On the other hand, a sample with the same PET/adhesive layer/glass configuration as above was autoclaved (40 ° C., 0.5 MPa, 30 min), and then P
A test sample was obtained by irradiating ultraviolet light from the ET film side so that the integrated light amount was 3000 mJ/cm ² . In this test sample, the other end of the adhesive sheet was peeled at a speed of 300 mm / min in the peeling direction of 180 degrees, and the adhesive strength to glass at that time (that is, after post-curing of the adhesive layer (in post-curing 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 pasted to a triacetyl cellulose film (Fuji Tac TD60UL, thickness 60 µm, manufactured by Fuji Film Co., Ltd.). Next, the first release sheet, which is a heavy separator film, is peeled off, and a PC plate having a thickness of 1 mm (polycarbonate plate without a hard coat layer: "Panlite PC1151" manufactured by Teijin)
). A sample having a structure of triacetylcellulose film/adhesive layer/PC board was autoclaved (40°C, 0.5MPa, 30min), and then irradiated with ultraviolet rays from the triacetylcellulose film side so that the integrated light amount was 3000mJ/cm ² . irradiate to
Test samples with dimensions of 100 mm x 200 mm were obtained. This test sample was allowed to stand in an environment of 85° C. and 85% relative humidity for 240 hours.

After that, the test sample was observed to see whether or not errors (lifting and peeling) occurred, and the durability was evaluated according to the following evaluation criteria.
A: No error was confirmed, and the durability was excellent.
B: An error of 1 mm or less was partially confirmed.
C: An error exceeding 1 mm was confirmed.

<Durability test 2>
Durability was evaluated by the same method and criteria as in Durability Test 1, except that the thickness of the PC board was changed to 2 mm.

<Workability>
The second release sheet, which is a light separator film of the adhesive layer, was peeled off, and a 25 μm thick P
It was laminated on the ET film. Next, peel off the first release sheet, which is a heavy separator film,
Sticked on the PC board. The PET/adhesive layer/PC sample thus obtained was autoclaved (40° C., 0.5 MPa, 30 min), and then irradiated with ultraviolet rays from the PET film side so that the integrated light amount was 3000 mJ/cm ² . A test sample was obtained by irradiating . Next, the edge of the test sample was cut using a guillotine cutter, and the cut edge was manually rubbed from the PC board side so as to peel off the PET film. The workability was evaluated by measuring the peeling distance at that time.
A: The peel distance was less than 0.05 mm, and the workability was excellent.
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 production conditions of the pressure-sensitive adhesive sheets of the above-described Examples and Comparative Examples. From Table 2, it can be seen that the adhesive sheets obtained in Examples have high adhesive strength, excellent blister resistance, and are less likely to lift or peel off from the adherend even in a high-temperature and high-humidity environment. It was shown to be excellent in terms of performance. In addition, the pressure-sensitive adhesive sheets of Examples had good workability. On the other hand, the pressure-sensitive adhesive sheet of the comparative example was selected from the following: Since one or more are not appropriate, the substrate adhesion (adhesive strength) and durability were poor.

Claims (9)

A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing a semi-cured product of a 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. containing an initiator (D),
The crosslinkable acrylic copolymer (A) is a non-crosslinkable (meth) acrylic acid ester unit (a1
) and a structural unit (a2) having an acidic functional group,
The non-crosslinkable (meth)acrylate unit (a1) includes a (meth)acrylic acid alkyl ester unit having an alkyl group having 2 or less carbon atoms and a (meth)acrylate having an alkyl group having 3 or more carbon atoms. containing acrylic acid alkyl ester,
The content of the structural unit (a2) is 5 to 15% by mass with respect to the total structural units contained in the crosslinkable acrylic copolymer (A),
The polyfunctional monomer (C) is 1 to 2 per 100 mass of the crosslinkable acrylic copolymer (A)
An adhesive sheet containing 0 parts by mass. The adhesive layer has a gel fraction of 50 to 80%, and
2. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a gel fraction of 75 to 90% when post-cured by irradiating the pressure-sensitive adhesive layer with an active energy ray so that the cumulative amount of light is 3000 mJ/cm ² . The pressure-sensitive adhesive layer has an adhesive strength of 5 N/25 mm or more, and
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has an adhesive strength of 10 N/25 mm or more when post-cured by irradiating the pressure-sensitive adhesive layer with an active energy ray so that the cumulative amount of light is 3000 mJ/cm ² . 4. A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different peel strengths on both sides of the pressure-sensitive adhesive sheet according to any one of claims 1 to 3. Having the pressure-sensitive adhesive sheet according to any one of claims 1 to 3 and an adherend provided on at least one side of the pressure-sensitive adhesive sheet,
The laminate, wherein the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state. Claim 5, wherein the adherend is one or more selected from the group consisting of a resin plate and a resin film.
The laminate according to . A step 1 of laminating an adherend on at least one side of the pressure-sensitive adhesive sheet according to any one of claims 1 to 3, and
A method for producing a laminate, comprising a step 2 of post-curing the adhesive layer of the adhesive sheet by irradiating the adhesive layer with an active energy ray. 8. The method for manufacturing a laminate according to claim 7, further comprising the step of processing the laminate after said 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.

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