Adhesive sheet, adhesive sheet with release sheet, laminate, and method for producing laminate

Abstract

To provide: 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 the adhesive sheet; and a method for producing a multilayer body.SOLUTION: An adhesive sheet is provided with 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) with an acidic functional group. The content of the constituent unit (a2) is 5-15 mass% based on the mass of all constituent units included in the crosslinkable acrylic copolymer (A). The glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to -20°C. The content of the polyfunctional monomer (C) is 5-20 pts.mass per 100 pts.mass of the crosslinkable acrylic copolymer (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive sheet, an adhesive sheet with a release sheet, a laminate, and a method for manufacturing the laminate.

Background Art

[0002] 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, a transparent adhesive sheet is used for applications such as bonding optical members, and a transparent adhesive sheet is also used for bonding a display device and an input device.

[0003] An adhesive composition for forming an adhesive sheet for an optical member is manufactured by a known polymerization method. Examples of this polymerization method include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. Among them, since it is easy to manufacture and an optically transparent adhesive sheet can be manufactured, an adhesive sheet using a solvent-based adhesive is widely used for the adhesive layer. Examples of the solvent-based adhesive include those having an acrylic resin as a main component. Such an acrylic resin is obtained by performing a polymerization reaction in a solvent in which an acrylic monomer is dissolved by a method called solution polymerization. In solution polymerization, as the polymerization progresses, the molecular weight of the polymer increases and the viscosity of the reaction solution increases. Therefore, there are technical limitations in synthesizing a polymer having a molecular weight necessary to obtain the cohesive force required for the adhesive. Therefore, in order to ensure the cohesive force required for the adhesive, a crosslinking agent capable of reacting with an acrylic resin such as an isocyanate-based compound or an epoxy-based compound is blended in the adhesive composition. Such a crosslinking agent reacts with the acrylic resin over time to construct a crosslinked network and increase the cohesive force of the adhesive layer.

[0004] In addition, as a method for forming an adhesive sheet for an optical member, a method of curing by two-stage curing in which polymerization is performed by active energy rays (or heat) after crosslinking by heat (or active energy rays) may be used. Such an adhesive sheet is formed from, for example, an adhesive composition having both thermosetting and active energy ray curability (hereinafter also referred to as a "dual-curing type adhesive composition"), and thus has thermosetting and active energy ray curability. Therefore, before bonding to the adherend, for example, by performing only thermosetting, a hardness that is easy to handle can be exhibited, and then, after bonding to the adherend, further curing with active energy rays (referred to as post-curing or after-cure) enables strong adhesion to the adherend.

[0005] For example, Patent Document 1 proposes an adhesive sheet having an adhesive layer in which the adhesive composition is in a semi-cured state, wherein the adhesive composition contains a crosslinkable acrylic polymer, a crosslinking agent, a polyfunctional monomer having two or more reactive double bonds in the molecule, and a photopolymerization initiator, and the adhesive sheet has a predetermined probe tack value or the like when the adhesive layer is post-cured. Such an adhesive sheet is excellent in processability and also excellent in high-temperature and high-humidity durability.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in recent years, with the increase in the size and performance of display devices and the like, the required performance for pressure-sensitive adhesive sheets has also been further enhanced. In particular, a pressure-sensitive adhesive sheet in which the curing shrinkage of the pressure-sensitive adhesive layer in the post-cured state 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 even more improved blister resistance, is strongly desired. In this regard, in pressure-sensitive adhesive sheets, adhesion (adhesive force) and blister resistance tend to be in a trade-off relationship with each other, so it has been difficult to further improve both performances.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a pressure-sensitive adhesive sheet having high adhesive force and excellent blister resistance, a pressure-sensitive adhesive sheet with a release sheet including the pressure-sensitive adhesive sheet and a laminate, and a method for manufacturing the laminate.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by configuring the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer with specific components, and have completed the present invention.

[0010] That is, the present invention includes, for example, the subject matters described in the following items. Item 1 A pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer containing a semi-cured product of a pressure-sensitive adhesive composition, The pressure-sensitive adhesive composition contains a crosslinkable acrylic copolymer (A), a crosslinking agent (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and a photopolymerization initiator (D), The crosslinkable acrylic copolymer (A) contains a structural unit (a2) having an acidic functional group, The content ratio of the structural unit (a2) is 5 to 15% by mass based on all the structural units contained in the crosslinkable acrylic copolymer (A), The glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to -20°C, The pressure-sensitive adhesive sheet, wherein the polyfunctional monomer (C) is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the crosslinkable acrylic copolymer (A). Item 2 The gel fraction of the pressure-sensitive adhesive layer is 50 to 80%, and when the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light quantity becomes 3000 mJ / cm 2 and then post-cured, the gel fraction is 75 to 90%. The pressure-sensitive adhesive sheet according to Item 1. Item 3 The adhesive strength of the pressure-sensitive adhesive layer is 5 N / 25 mm or more, and when the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light quantity becomes 3000 mJ / cm 2 and then post-cured, the adhesive strength is 10 N / 25 mm or more. The pressure-sensitive adhesive sheet according to Item 1 or 2. Item 4 A pressure-sensitive adhesive sheet with a release sheet, comprising a pair of release sheets having different release forces on both sides of the pressure-sensitive adhesive sheet according to any one of Items 1 to 3. Item 5 A laminate having the pressure-sensitive adhesive sheet according to any one of Items 1 to 3 and an adherend provided on at least one surface side of the pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state. Item 6 The laminate according to Item 5, wherein the adherend is at least one selected from the group consisting of a resin plate and a resin film. Item 7 Step 1 of laminating an adherend on at least one surface side of the pressure-sensitive adhesive sheet according to any one of Items 1 to 3, and Step 2 of post-curing the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer with active energy rays. A method for manufacturing a laminate. Item 8 The method for manufacturing a laminate according to Item 7, further comprising a step of processing the laminate after Step 2. Item 9 The method for manufacturing a laminate according to Item 7 or 8, wherein the thickness of the pressure-sensitive adhesive layer is 5 to 150 μm.

Advantages of the Invention

[0011] The pressure-sensitive adhesive sheet according to the present invention has a high adhesive force and excellent blister resistance. Therefore, the pressure-sensitive adhesive sheet according to the present invention is less likely to float or peel from the adherend even in a high-temperature and high-humidity environment, and has excellent adhesion and durability.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "containing" and "including" include the concepts of "containing", "including", "consisting essentially of", and "consisting only of".

[0014] Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0015] In this specification, "(meth)acrylate" represents both acrylate and methacrylate, or either one, and "(meth)acrylic acid" represents both acrylic acid and methacrylic acid, or either one.

[0016] Also, in this specification, "monomer" and "monomer" are synonymous, and "polymer" and "polymer" are synonymous.

[0017] 1. Adhesive sheet The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer containing a semi-cured product of a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition contains a crosslinkable acrylic copolymer (A), a crosslinking agent (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and a photopolymerization initiator (D).

[0018] In the pressure-sensitive adhesive sheet of the present invention, 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 5 to 15% by mass based on all the structural units contained in the crosslinkable acrylic copolymer (A). The glass transition temperature of the crosslinkable acrylic copolymer (A) is -40 to -20°C, and the polyfunctional monomer (C) is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the crosslinkable acrylic copolymer (A).

[0019] 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 a high adhesive force and excellent blister resistance. Conventionally, from the viewpoints of weight reduction and impact resistance improvement, resin plates such as polycarbonate and polymethyl methacrylate may be used in applications such as display devices. However, when these resin plates are used, a blister phenomenon in which foaming and floating occur in the pressure-sensitive adhesive layer easily occurs in a high-temperature and high-humidity environment, that is, there is a problem with blister resistance. However, the pressure-sensitive adhesive sheet according to the present invention is less likely to cause a blister phenomenon than before, and it is less likely to float or peel from the adherend even in a high-temperature and high-humidity environment, and has excellent adhesion and durability.

[0020] The pressure-sensitive adhesive composition is a raw material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, and in particular, it is the dual-curing type pressure-sensitive adhesive composition. As described above, the pressure-sensitive adhesive composition contains, as constituent components, at least a crosslinkable acrylic copolymer (A), a crosslinking agent (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, and a photopolymerization initiator (D).

[0021] (Crosslinkable acrylic copolymer (A)) The crosslinkable acrylic copolymer (A) is a polymer containing at least a (meth)acrylic-based structural unit and a structural unit (a2) having an acidic functional group, and having a glass transition temperature in the range of -40°C or higher and -20°C or lower. In the present specification, the "unit" or "structural unit" in the (meth)acrylic-based structural unit is a repeating unit (also referred to as a monomer unit) constituting the polymer.

[0022] Examples of the (meth)acrylic-based structural unit include one or two or more different non-crosslinkable (meth)acrylic acid ester units (a1). Therefore, examples of the crosslinkable acrylic copolymer (A) include a copolymer containing one or two or more different non-crosslinkable (meth)acrylic acid ester units (a1) and a structural unit (a2) having an acidic functional group.

[0023] The non-crosslinkable (meth)acrylic acid ester unit (a1) is a repeating unit derived from a (meth)acrylic acid alkyl ester. The (meth)acrylic acid alkyl ester preferably includes both a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester has 2 or less carbon atoms and a (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms. In this case, the crosslinkable acrylic copolymer (A) is likely to have the glass transition temperature in the above range, and the cohesive force of the polymer component is likely to increase even after the adhesive layer is post-cured. As a result, the blister resistance performance of the adhesive sheet is likely to be improved.

[0024] Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 2 or less carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, etc. These may be used alone or in combination of two or more. The (meth)acrylic acid alkyl ester in which the alkyl group has 2 or less carbon atoms is preferably methyl (meth)acrylate and / or ethyl (meth)acrylate.

[0025] Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms include propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and the like. These may be used alone or in combination of two or more.

[0026] In the (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms, the number of carbon atoms of the alkyl group is preferably 4 or more, and preferably 18 or less, more preferably 12 or less, and even more preferably 8 or less.

[0027] The (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms preferably contains at least one selected from n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate in that the adhesiveness of the pressure-sensitive adhesive sheet tends to be high.

[0028] When the (meth)acrylic acid alkyl ester contains both a (meth)acrylic acid alkyl ester in which the alkyl group has 2 or less carbon atoms and a (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms, from the viewpoint that the cohesive force of the polymer component is likely to increase and foaming is likely to be suppressed even after the adhesive layer is post-cured, and the blister resistance performance of the adhesive sheet is likely to be improved, the content ratio of the two can be as follows. That is, with respect to the total amount of the (meth)acrylic acid alkyl ester in which the alkyl group has 2 or less carbon atoms and the (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms, the (meth)acrylic acid alkyl ester in which the alkyl group has 3 or more carbon atoms is preferably 40% by mass or more, more preferably 45% by mass or more, still more preferably 50% by mass or more, particularly preferably 54% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, particularly preferably 80% by mass or less.

[0029] The non-crosslinkable (meth)acrylic acid ester unit (a1) can include (meth)acrylic acid alkyl ester units other than (meth)acrylic acid alkyl ester units in which the alkyl group has 2 or less carbon atoms and (meth)acrylic acid alkyl ester units in which the alkyl group has 3 or more carbon atoms. Alternatively, the non-crosslinkable (meth)acrylic acid ester unit (a1) may consist only of (meth)acrylic acid alkyl ester units in which the alkyl group has 2 or less carbon atoms and (meth)acrylic acid alkyl ester units in which the alkyl group has 3 or more carbon atoms.

[0030] Incidentally, although it is just a note for safety, 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.

[0031] In the (meth)acrylic acid alkyl ester, the alkyl group may be either linear or branched.

[0032] In the structural unit (a2) having an acidic functional group, the acidic functional group is acidic and, in particular, is a functional group capable of promoting a crosslinking reaction with a crosslinking agent (B) described later. Examples of such acidic functional groups include a carboxy group or a group derived from a carboxy group, a sulfo group or 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 is more likely to have a higher adhesive force, and the durability is also particularly likely to be improved, so that the blister resistance is more excellent. Examples of the carboxy group-containing monomer include acrylic acid and methacrylic acid. These may be used alone or in combination of two or more.

[0033] As described above, the content ratio of the structural unit (a2) is 5 to 15% by mass based on all the structural units contained in the crosslinkable acrylic copolymer (A). Thereby, the pressure-sensitive adhesive sheet is more likely to have a higher adhesive force and the durability is also likely to be improved. The content ratio of the structural unit (a2) is more preferably 5 to 10% by mass based on all the structural units contained in the crosslinkable acrylic copolymer (A).

[0034] The crosslinkable acrylic copolymer (A) may further contain other constitutional units in addition to the non-crosslinkable (meth)acrylic acid ester unit (a1) and the constitutional unit (a2) having an acidic functional group. Examples of the other constitutional units can broadly include constitutional units derived from monomers copolymerizable with acrylic monomers, and specifically include (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl pyrrolidone, vinyl pyridine, and the like. As the other constitutional units, monomers 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, or an isocyanate group. Note that the crosslinkable acrylic copolymer (A) is a polymer formed of (meth)acrylic-based constitutional units, and as long as it is a polymer having a glass transition temperature in the range of -40°C or higher and -20°C or lower, it may be a copolymer other than the copolymer containing the non-crosslinkable (meth)acrylic acid ester unit (a1) and the constitutional unit (a2) having an acidic functional group.

[0035] The crosslinkable acrylic copolymer (A) can also be a copolymer composed only of the non-crosslinkable (meth)acrylic acid ester unit (a1) and the constitutional unit (a2) having an acidic functional group. The crosslinkable acrylic copolymer (A) is usually a random copolymer.

[0036] The crosslinkable acrylic copolymer (A) has a glass transition temperature in the range of -40 to -20°C. As a result, the cohesive force of the polymer component in the adhesive layer increases, making it easier to suppress foaming. Consequently, the blister resistance performance of the adhesive sheet is likely to be improved.

[0037] The glass transition temperature of the crosslinkable acrylic copolymer (A) preferably exceeds -40°C (that is, -40°C is not included), and more preferably is -35°C or higher. Also, the glass transition temperature of the crosslinkable acrylic copolymer (A) is preferably less than -20°C, and more preferably is -25°C or lower.

[0038] The method for adjusting the glass transition temperature of the crosslinkable acrylic copolymer (A) is not particularly limited. For example, a method of adjusting the content ratios of (meth)acrylic acid alkyl ester units having 2 or less carbon atoms in the alkyl group, (meth)acrylic acid alkyl ester units having 3 or more carbon atoms in the alkyl group, and the constitutional unit (a2) having an acidic functional group can be mentioned.

[0039] In the present invention, the glass transition temperature of the crosslinkable acrylic copolymer (A) refers to Tg determined by the following Fox's equation based on the composition of the monomers used in the synthesis of the copolymer. Fox's equation: 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), Tg1, Tg2, ···, Tgm are the glass transition temperatures of the respective homopolymers of the m types of monomers (m is an integer) constituting the crosslinkable acrylic copolymer (A), and W1, W2, ···, Wm are the mass fractions of the respective constitutional units in the crosslinkable acrylic copolymer (A). Note that Tg1 and W1 are in 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 constitutional unit having a mass fraction of W1. Similarly, Tg2 and W2, ···, Tgm and Wm are in corresponding relationships with each other.

[0040] As the glass transition temperature of the aforementioned homopolymer, for example, the values described in Polymer Handbook 4th Edition (Wiley-Interscience 2003) can be used. When there is no description in such a handbook, for example, the glass transition temperature of the homopolymer can be measured by a differential scanning calorimeter (DSC). As the measurement conditions of DSC, 5 mg of the sample is used, under a nitrogen atmosphere. In the first measurement (1st RUN), the temperature is raised from -100 °C to 200 °C at a rate of 5 °C / min, then cooled to -100 °C at a rate of 5 °C / min, and further in the second measurement (2nd RUN), the temperature is raised from -100 °C to 200 °C at a rate of 5 °C / min. Here, the glass transition temperature refers to the intersection of the extension line of the baseline on the low-temperature side of 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 sigmoidally in the endothermic direction and the tangent line at the inflection point of the sigmoid.

[0041] The weight average molecular weight of the crosslinkable acrylic copolymer (A) is preferably from 200,000 to 2,000,000, more preferably from 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 adhesive layer, and it is easy to develop the hardness after post-curing, and the processability is excellent. The weight average molecular weight of the crosslinkable acrylic copolymer (A) is the value before crosslinking with the crosslinking agent. The weight average molecular weight is measured by size exclusion chromatography (SEC) and is the value determined based on polystyrene. As the crosslinkable acrylic copolymer, commercially available products may be used, or those synthesized by known methods may be used.

[0042] The production method of the crosslinkable acrylic copolymer (A) is not particularly limited, and for example, the same method as the known method for producing an acrylic copolymer can be adopted.

[0043] For example, a crosslinkable acrylic copolymer (A) can be produced by a polymerization reaction of a monomer mixture containing an alkyl (meth)acrylate 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. The conditions of the polymerization reaction are not particularly limited, and for example, known polymerization reactions can be widely employed.

[0044] (Crosslinking agent B) The crosslinking agent (B) is not particularly limited as long as it can promote the crosslinking reaction of the crosslinkable acrylic copolymer, and for example, known crosslinking agents can be widely used. For example, the crosslinking agent (B) can be selected from known crosslinking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds. Among these, since a carboxy group-containing acrylate can be easily crosslinked, it is preferable to use an epoxy compound. That is, the crosslinking agent is preferably a difunctional or higher-functional epoxy compound.

[0045] 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, 1,6-hexanediol diglycidyl ether, tetraglycidyl xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and the like.

[0046] The content of the crosslinking agent in the adhesive composition is appropriately selected according to the desired adhesiveness and the like. However, it is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the crosslinkable acrylic copolymer (A). By setting the content of the crosslinking agent (B) within the above range, the adhesion to the base material can be enhanced, and the processability can be further enhanced. The crosslinking agent (B) may be used alone or in combination of two or more kinds. When two or more kinds are used in combination, it is preferable that the total mass is within the above range.

[0047] (Polyfunctional monomer (C)) The polyfunctional monomer (C) is a compound having two or more polymerizable double bonds in the molecule. When the polyfunctional monomer (C) is contained in the adhesive composition, when the adhesive layer in the semi-cured state is post-cured, the radical polymerization reaction of the polyfunctional monomer (C), particularly the crosslinking reaction, proceeds, whereby the adhesive layer is post-cured and becomes a post-cured state.

[0048] Examples of the polyfunctional monomer (C) include ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,6-hexanediol diacrylate, polybutylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, diacrylate of bisphenol A diglycidyl ether, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate and other (meth)acrylic esters of polyhydric alcohols, vinyl methacrylate, and the like. These may be used alone or in combination of two or more kinds.

[0049] The polyfunctional monomer (C) has two or more polymerizable double bonds, preferably two or more and less than five, and more preferably two or more and less than four.

[0050] As the polyfunctional monomer (C), for example, commercially available products can be used. Examples of 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) manufactured by Toagosei Co., Ltd.

[0051] 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 adhesive layer after post-curing can be more effectively increased, and the processability of the adhesive sheet is likely to be improved. Examples of such a polyfunctional monomer (C) include diacrylate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, and diacrylate of bisphenol F diglycidyl ether.

[0052] The glass transition temperature (Tg) of the polyfunctional monomer (C) as a homopolymer is preferably 30°C or higher, and more preferably 50°C or higher. The glass transition temperature (Tg) of the polyfunctional monomer as 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 adhesive sheet can be more effectively increased. As the glass transition temperature, literature values 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 measured using a DSC (differential scanning calorimeter) can be adopted.

[0053] In the pressure-sensitive adhesive composition, the polyfunctional monomer (C) is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the crosslinkable acrylic copolymer (A). As a result, the curing shrinkage of the pressure-sensitive adhesive layer in the post-curing state is less likely to occur due to the post-curing treatment. As a result, the pressure-sensitive adhesive sheet has improved adhesive strength and excellent blister resistance. In particular, since the crosslinkable acrylic copolymer (A) has a higher Tg and stronger cohesive force of the polymer component than in the past, it is considered that curing shrinkage is more likely to occur. However, conversely, in the present invention, when a specific amount of the polyfunctional monomer (C) is contained, such curing shrinkage is less likely to occur. As a result, while maintaining the high adhesive strength of the pressure-sensitive adhesive sheet, excellent blister resistance can also be achieved.

[0054] In the pressure-sensitive adhesive composition, the polyfunctional monomer (C) is preferably contained in an amount exceeding 1 part by mass per 100 parts by mass of the crosslinkable acrylic copolymer (A), and more preferably 5 parts by mass or more. Further, the polyfunctional monomer (C) is preferably contained in an amount of 20 parts by mass or less per 100 parts by mass of the crosslinkable acrylic copolymer (A), and more preferably 15 parts by mass or less.

[0055] (Photoinitiator (D)) The pressure-sensitive adhesive composition contains a photoinitiator (D). The photoinitiator preferably initiates the polymerization of the crosslinkable acrylic copolymer and the polyfunctional monomer by irradiation with active energy rays in the post-curing treatment. As the photoinitiator (D), a known photoinitiator can be used. "Active energy rays" means those having energy quanta among electromagnetic waves or charged particle beams, and examples include ultraviolet rays, electron beams, visible light rays, X-rays, ion beams, and the like. Among them, ultraviolet rays or electron beams are preferred from the viewpoint of versatility, and ultraviolet rays are particularly preferred.

[0056] Examples of the photoinitiator (D) include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, thioxanthone-based initiators, amine-based initiators, acylphosphine oxide-based initiators, and the like.

[0057] Specific examples of acetophenone-based initiators include diethoxyacetophenone, benzyldimethylketal, etc. Specific examples of benzoin ether-based initiators include benzoin, benzoin methyl ether, etc. Specific examples of benzophenone-based initiators include benzophenone, methyl o-benzoylbenzoate, etc.

[0058] Specific examples of hydroxyalkylphenone-based initiators include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by IGM Resins B.V., commercially available as Omnirad184), etc. Specific examples of thioxanthone-based initiators include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, etc. Specific examples of amine-based initiators include triethanolamine, ethyl 4-dimethylbenzoate, etc. Specific examples of acylphosphine oxide-based initiators include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by IGM Resins B.V., commercially available as Omnirad819), etc.

[0059] Other examples of the photopolymerization initiator (D) include, for example, alkylphenone-based photopolymerization initiators such as 2,2-dimethoxy-2-phenylacetophenone, 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-propanone, acylphosphine oxide-based polymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl)phenylphosphine oxide, intramolecular hydrogen abstraction-type photopolymerization initiators such as methyl benzoylformate and 4-methylbenzophenone, as well as oxime ester-based photopolymerization initiators, cationic photopolymerization initiators, and the like.

[0060] The content of the photopolymerization initiator (D) in the pressure-sensitive adhesive composition is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the crosslinkable acrylic copolymer (A). If it is within the above range, it can be adjusted to a desired hardness by post-curing, and the molecular weight after post-curing can be within an appropriate range, so that a pressure-sensitive adhesive sheet excellent in processability can be obtained. As the photopolymerization initiator (D), one kind may be used alone or two or more kinds may be used in combination. When two or more kinds are used in combination, the total mass is preferably within the above range.

[0061] (Solvent) From the viewpoint of improving the coating property, the pressure-sensitive adhesive composition may contain a solvent. 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; alcohols such as methanol, ethanol, 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; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; and polyols and their derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate.

[0062] 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, more preferably 30 to 400 parts by mass, based on 100 parts by mass of the crosslinkable acrylic copolymer (A). Further, 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. The solvent 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.

[0063] (Other components and preparation method of the pressure-sensitive adhesive composition) The pressure-sensitive adhesive composition may contain other components other than the above, as long as the effects of the present invention are not impaired. As other components, it can include a monofunctional monomer having one reactive double bond in the molecule. The type of such monofunctional monomer is not particularly limited. For example, monofunctional monomers contained in known pressure-sensitive adhesive compositions can be widely used.

[0064] The pressure-sensitive adhesive composition can contain various additives for pressure-sensitive adhesives, as long as the effects of the present invention are not impaired. Such additives can be selected as needed from, for example, plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, etc. Also, dyes or pigments may be added for coloring purposes.

[0065] Examples of plasticizers include vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl capric acid, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl benzoate, and styrene.

[0066] Examples of antioxidants include phenolic antioxidants, amine antioxidants, lactone antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. These antioxidants may be used alone or in combination of two or more.

[0067] As a metal corrosion inhibitor, a benzotriazole-based resin can be cited as a preferable example in terms of the compatibility and high effectiveness with the adhesive.

[0068] Examples of the tackifier include rosin-based resins, terpene-based resins, terpene phenol-based resins, coumarone indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, petroleum resins, and the like.

[0069] Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto group-substituted alkoxy oligomers, etc.).

[0070] Examples of the ultraviolet absorber include benzotriazole-based compounds, benzophenone-based compounds, and the like. 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.

[0071] The method for preparing the adhesive composition is not particularly limited. For example, a crosslinkable acrylic copolymer (A), a crosslinking agent (B), a polyfunctional monomer (C) having two or more polymerizable double bonds in the molecule, a photopolymerization initiator (D), and, if necessary, a solvent and other components, etc. are mixed at a predetermined blending ratio to prepare the adhesive composition.

[0072] (Adhesive layer) The adhesive layer is formed by bringing the adhesive composition into a semi-cured state. That is, the adhesive layer contains a semi-cured product of the adhesive composition and has post-curing properties.

[0073] The adhesive layer can be formed only from the semi-cured product of the adhesive composition, or, as long as the effects of the present invention are not inhibited, the adhesive layer can also contain components other than the semi-cured product of the adhesive composition.

[0074] In the present invention, when the gel fraction of the pressure-sensitive adhesive layer increases by 10% by mass or more compared to before irradiation by irradiating active energy rays, it is assumed that the pressure-sensitive adhesive layer before irradiation is in a semi-cured state. The irradiation with active energy rays in this case is performed as follows. First, an optical transparent PET separator is bonded to both sides of the pressure-sensitive adhesive layer. Then, active energy rays (high-pressure mercury lamp or metal halide lamp) are irradiated from one side of the optical transparent PET separator so that the integrated light quantity becomes 3000 mJ / cm 2 By measuring the gel fraction of the pressure-sensitive adhesive layer formed by this irradiation and examining whether it has increased by 10% by mass or more before and after irradiation, it is possible to determine whether the pressure-sensitive adhesive layer before irradiation was in a semi-cured state.

[0075] 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 (pressure-sensitive adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and it is shaken for 24 hours. Then, the contents of this sample bottle are filtered through a 150-mesh stainless steel 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 (mass%) = (dry mass / collected mass of the pressure-sensitive adhesive layer) × 100 ··· Formula 1 The gel fraction can be determined according to.

[0076] In the present invention, the "semi-cured state" is preferably the state after heat-curing the pressure-sensitive adhesive composition. It is preferable to perform "post-curing" by irradiating active energy rays after this heat treatment. That is, it is preferable that the pressure-sensitive adhesive layer is in a semi-cured state by heat-curing the pressure-sensitive adhesive composition, and it is preferable that it has active energy ray curability.

[0077] In the adhesive sheet of the present invention, the gel fraction of the pressure-sensitive adhesive layer is 50 to 80%, and active energy rays are irradiated to the pressure-sensitive adhesive layer so that the integrated light quantity becomes 3000 mJ / cm 2It is preferable that the gel fraction is 75 to 90% when irradiated and post-cured. In this case, even in the post-cured state, the adhesion is maintained, and the cohesive force of the polymer in the adhesive layer in the post-cured state can be increased. As a result, foaming of the adhesive layer can be suppressed even in a high-temperature and high-humidity environment. Although it is only a precautionary note, the gel fraction of 50 to 80% of the adhesive layer means that the gel fraction of the semi-cured adhesive layer is 50 to 80%. The gel fraction of such an adhesive layer is more preferably 60 to 80%, and even more preferably 65 to 80%. When measuring the gel fraction after irradiating the adhesive layer with active energy rays and curing, the irradiation of the active energy rays is performed as follows. First, an optical transparent PET separator is bonded to both sides of the adhesive layer. Then, active energy rays (high-pressure mercury lamp or metal halide lamp) are irradiated from one side of the optical transparent PET separator so that the integrated light quantity is 3000 mJ / cm 2 and the gel fraction of the adhesive layer formed by this irradiation is measured.

[0078] Incidentally, from the viewpoint of easily suppressing curing shrinkage, the difference between the gel fraction in the semi-cured state of the adhesive layer and the gel fraction after post-curing is preferably 5% or more and preferably 20% or less.

[0079] 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 adhesive layer is preferably 5 to 150 μm, more preferably 8 to 100 μm, even more preferably 10 to 80 μm, and particularly preferably 10 to 40 μm. By setting the thickness of the adhesive layer within the above ranges, bleeding and stickiness of the adhesive can be suppressed, so that the processability can be improved. Furthermore, by setting the thickness of the adhesive layer within the above ranges, the production of the adhesive sheet becomes easy.

[0080] In the adhesive sheet of the present invention, the adhesive force of the adhesive layer is 5 N / 25 mm or more, and active energy rays are applied to the adhesive layer with an integrated light quantity of 3000 mJ / cm 2It is preferable that the adhesive strength when irradiated and post-cured is 10 N / 25 mm or more. Thereby, even after the adhesive layer is post-cured, it can have excellent adhesion to the substrate. Also in this case, the adhesive strength being 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 adhesive layer with active energy rays for curing, the irradiation conditions of the active energy rays are the same as those in the case of measuring the post-cured gel fraction described above.

[0081] The adhesive strength of the adhesive layer and the adhesive strength after the adhesive layer is post-cured strongly depend on the composition of the adhesive composition. In particular, by forming the adhesive layer using an adhesive composition in which the Tg of the crosslinkable acrylic copolymer (A) and the content ratio of the polyfunctional monomer (C) are adjusted within a predetermined range, the adhesive strength of the adhesive layer and the adhesive strength after the adhesive layer is post-cured can be made to the desired magnitude.

[0082] The adhesive strength is a value measured by the following method. Peel off the second release sheet which is the above-mentioned light separator film of the adhesive layer, bond it to a PET film with a thickness of 50 μm, and cut it into a width of 25 mm. After cleaning the tin-free surface of the float glass with ethanol, peel off the first release sheet which is the above-mentioned heavy separator film of the adhesive sheet, and reciprocate a 2 kg roller to bond the adhesive surface of the adhesive sheet to the glass. After subjecting the obtained sample having a structure of PET / adhesive layer / glass to autoclave treatment (40 °C, 0.5 MPa, 30 min), peel the other end of this sample in the peeling direction of 180 degrees at a speed of 300 mm / min, and take the adhesive strength with respect to the glass at that time as the adhesive strength of the adhesive layer (that is, the adhesive strength of the adhesive layer in the semi-cured state). On the other hand, a sample having the same structure of PET / adhesive layer / glass as described above is subjected to autoclave treatment (40 °C, 0.5 MPa, 30 min), and then ultraviolet rays are irradiated from the PET film side with an integrated light amount of 3000 mJ / cm 2Irradiate so as to obtain a test sample. In this test sample, the other end of the pressure-sensitive adhesive sheet is peeled in the peeling direction of 180 degrees at a speed of 300 mm / min, and the adhesive force to the glass at that time is defined as the adhesive force after post-curing (that is, the adhesive force in the post-cured state (in the post-cured state) of the pressure-sensitive adhesive layer).

[0083] (Pressure-sensitive adhesive sheet) As described above, 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. Therefore, the pressure-sensitive adhesive sheet of the present invention has post-curability, particularly active energy ray curability.

[0084] 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. For example, it can have the same configuration as a known pressure-sensitive 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 provided with a base material (preferably a transparent base material) on one side, or further, a double-sided pressure-sensitive adhesive sheet.

[0085] 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-layer pressure-sensitive adhesive sheet in which a plurality of pressure-sensitive adhesive layers are laminated, a multi-layer pressure-sensitive adhesive sheet in which another pressure-sensitive adhesive layer is laminated between the pressure-sensitive adhesive layers, a multi-layer pressure-sensitive adhesive sheet in which a support is laminated between the 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 the support and another pressure-sensitive adhesive layer is laminated on the other side. 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 similar to the transparent base material can be used. Since such a pressure-sensitive adhesive sheet is also excellent in transparency as a whole, it can be suitably used for bonding optical members.

[0086] When the pressure-sensitive adhesive sheet of the present invention is a single-sided pressure-sensitive adhesive sheet, as shown in FIG. 1, it may have a configuration in which a transparent base material 12a is 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 a release sheet 12b. When using the pressure-sensitive adhesive sheet, it is preferable to peel off this release sheet 12b and bond it so that the pressure-sensitive adhesive layer 11 adheres closely to a desired adherend, and then perform post-curing by irradiating active energy rays or the like. As the transparent base material, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, cycloolefin polymer film, etc. can be used. Also, an easy-adhesion layer may be provided on the pressure-sensitive adhesive layer side of these transparent base materials. Furthermore, functional layers such as a hard coat layer, an antireflection layer, an antifouling layer, and an ultraviolet absorption layer may be provided on the surface opposite to the pressure-sensitive adhesive layer of the transparent base material.

[0087] The present invention includes a pressure-sensitive adhesive sheet with release sheets provided on both sides of the pressure-sensitive adhesive sheet. Such a pressure-sensitive adhesive sheet with release sheets can be provided with a pair of release sheets having different release forces on both sides of the pressure-sensitive adhesive sheet. For example, as shown in FIG. 1, release sheets 12a and 12b can be provided on both sides of the pressure-sensitive adhesive layer 11.

[0088] Examples of the release sheet include a release laminate 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.

[0089] For the release sheet base material in the release laminate sheet, papers and polymer films are used. As the release agent constituting the release agent layer, for example, general-purpose addition-type or condensation-type silicone-based release agents or long-chain alkyl group-containing compounds are used. In particular, addition-type silicone-based release agents with high reactivity are preferably used.

[0090] As silicone-based release agents, specifically, BY24-4527, SD-7220, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3600, KS-774, X62-2600, etc. manufactured by Shin-Etsu Chemical Co., Ltd. can be mentioned. Further, it is preferable to contain a silicone resin which is an organosilicon compound having SiO 2 units and (CH 3 ) 3 SiO 1 / 2 units or CH 2 =CH(CH 3 )SiO 1 / 2 units. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

[0091] As the release laminate sheet, a commercially available product may be used. For example, a heavy separator film which is a polyethylene terephthalate film subjected to a release treatment manufactured by Teijin DuPont Film Co., Ltd., and a light separator film which is a polyethylene terephthalate film subjected to a release treatment manufactured by Teijin DuPont Film Co., Ltd. can be mentioned.

[0092] 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 release forces from each other. That is, in order to make it easy to peel off the release sheet, it is preferable that the releasability of the release sheet 12a and the release sheet 12b is different. When the releasability from one side is different from the releasability from the other side, it becomes easy to peel off only the release sheet having the higher releasability first. In that case, the releasability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding order.

[0093] Further, the present invention may relate to an adhesive sheet with a transparent film provided 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 adhesive sheet with a transparent film may be a sheet in which a transparent film / adhesive sheet / release sheet are laminated in this order.

[0094] The method for manufacturing the adhesive sheet of the present invention is not particularly limited. For example, a known method for manufacturing an adhesive sheet can be widely adopted. For example, the adhesive sheet of the present invention can be manufactured by a manufacturing method including a step of applying the adhesive composition on a release sheet to form a coating film, and a step of heating this coating film to obtain a semi-cured product (semi-cured material) in a semi-cured state. In this case, by heating the coating film, the reaction between the crosslinkable acrylic copolymer (A) and the crosslinking agent (B) proceeds to form a semi-cured product (that is, an adhesive layer). During heating, in the coating film, the polymerization reaction of the monomer by the photopolymerization initiator (D) does not proceed or proceeds only slightly. Therefore, in the adhesive layer, at least a part of the polymerizable monomer (such as the polyfunctional monomer (C)) and the photopolymerization initiator (D) derived from the adhesive composition are contained in an unreacted state.

[0095] In addition, in order to make the adhesive composition in a semi-cured state, it is preferable to perform an aging treatment in which the adhesive sheet is allowed to stand at a constant temperature for a certain period after removing the solvent after coating. The aging treatment can be performed, for example, by allowing it to stand at 23°C for 7 days.

[0096] The application of the 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 microgravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and the like.

[0097] For heating the coating film formed by applying the pressure-sensitive adhesive composition, known heating devices such as a heating furnace and an infrared lamp can be used.

[0098] The method of using the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and it can be used in various ways according to the application, purpose, etc. For example, the pressure-sensitive adhesive sheet is preferably used by a method of bringing the pressure-sensitive adhesive layer into contact with the surface of the adherend. Specifically, it is preferable to bond the adherend when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state and irradiate active energy rays to post-cure the pressure-sensitive adhesive layer. Since the pressure-sensitive adhesive sheet of the present invention is a two-stage curing type pressure-sensitive adhesive sheet, it has a pressure-sensitive adhesive layer semi-cured only by heat before bonding, and has the property that the pressure-sensitive adhesive layer is post-cured by active energy rays after bonding. Therefore, various usage methods suitable for this property can be adopted. Note that the adherend is the same as the adherend in the laminate described later.

[0099] The pressure-sensitive adhesive sheet of the present invention has a high adhesive strength and excellent blister resistance, so it is difficult for peeling or peeling from the adherend to occur even in a high-temperature and high-humidity environment, and it has excellent adhesion and durability. Therefore, even when the pressure-sensitive adhesive sheet of the present invention is used for applications such as bonding large-screen optical members, wrinkles are hardly generated and the processability is also excellent.

[0100] In addition, the pressure-sensitive adhesive sheet of the present invention has suppressed end face stickiness after post-curing, and for example, it can prevent the adhesion of the pressure-sensitive adhesive to the punching blade during punching and the accompanying deformation of the pressure-sensitive adhesive layer. Furthermore, 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 finishing the end face after punching to a desired size after post-curing, and it also has excellent processability.

[0101] The pressure-sensitive adhesive sheet of the present invention is bonded to an adherend such as a base material and post-cured, and even when exposed to a high-temperature and high-humidity environment, it has excellent base material adhesion and durability, so the occurrence of floating and peeling can be suppressed. The pressure-sensitive adhesive sheet of the present invention can suppress, for example, floating or peeling from the polycarbonate base material even when bonded to a polycarbonate base material, post-cured, and then exposed to a high-temperature and high-humidity environment.

[0102] In this specification, the durability of the pressure-sensitive adhesive sheet can be evaluated by the following method. First, a triacetyl cellulose film is bonded to one surface of the pressure-sensitive adhesive sheet, and a polycarbonate plate is bonded to the other surface. Actinic rays are irradiated from the surface on the triacetyl cellulose film side so that the integrated light quantity is 3000 mJ / cm 2 and the adhesive layer is post-cured. Then, the pressure-sensitive adhesive sheet is allowed to stand in an environment of 85°C and 85% relative humidity for 240 hours each. Then, the pressure-sensitive adhesive sheet is observed, and it can be determined that the durability is excellent when floating or peeling from the polycarbonate plate and / or the triacetyl cellulose film is suppressed.

[0103] As described above, the pressure-sensitive adhesive sheet of the present invention is an optical member that requires durability, and is preferably used for bonding optical members that require molding after lamination with the 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. The polarizing plate includes a polarizer and a polarizer protection film. The pressure-sensitive adhesive sheet of the present invention is preferably bonded to the polarizer protection film. As the polarizer protection film, resin films and the like can be widely used. For example, cycloolefin-based resin films, cellulose acetate-based resin films such as triacetyl cellulose and diacetyl cellulose, polyester-based resin films such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polycarbonate-based resin films, acrylic-based resin films, polypropylene-based resin films, and the like can be mentioned.

[0104] 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 case where the pressure-sensitive adhesive sheet of the present invention is used for bonding two adherends include bonding of transparent optical films inside a touch panel, bonding of a transparent optical film and glass, bonding of a transparent optical film of a touch panel and a liquid crystal panel, bonding of a cover panel and a transparent optical film, bonding of a cover panel and a transparent optical film, etc. In particular, it is useful when any member is a polycarbonate substrate. As the transparent optical film, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, cycloolefin polymer film, etc. 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.

[0105] 2. Laminate The present invention includes a laminate having the above-described pressure-sensitive adhesive sheet and an adherend. Such a laminate has the 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 laminate, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state, that is, the semi-cured pressure-sensitive adhesive layer has been post-cured.

[0106] In the laminate of the present invention, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a post-cured state by irradiating active energy rays. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, it is preferable to form the laminate by irradiating active energy rays in a state where two adherends are bonded with the semi-cured pressure-sensitive adhesive sheet to post-cure the pressure-sensitive adhesive layer. Here, at least one of the adherends can include a substrate, an optical member, etc. More specifically, a resin plate, a resin film, glass, etc. are exemplified, and other known polarizing plates, etc. are also exemplified. The adherend may have a single-layer structure or a laminated structure formed by laminating different materials.

[0107] In the laminate, it is particularly preferable that at least one adherend is a resin plate. Examples of the resin film include known transparent films. When the adherends are laminated on both sides of the adhesive sheet, the adherends may be of the same type or different types.

[0108] 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, the thickness of the adherend is not particularly limited. For example, as the adherend, a resin plate having a thickness of 250 μm or more can be applied, or a resin film having a thickness of less than 250 μm can also be applied.

[0109] The type of the resin plate is not particularly limited. For example, a base material formed of a known resin can be widely used. Examples include polycarbonate (PC) plates, polymethacrylate (PMMA) plates, etc., as well as "Iupilon MR58" manufactured by Mitsubishi Gas Chemical, "Paramitei MT3LTR" manufactured by Kuraray, "Panlite PC1151" manufactured by Teijin, etc. Further, the resin plate may have a laminated structure formed of different materials. For example, it can have a two-layer structure of two types such as PMMA / PC or a three-layer structure of two types such as PMMA / PC / PMMA. The resin plate may have a known hard coat layer.

[0110] 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 configuration of a laminate 20 in which the adhesive sheet 21 of the present invention is bonded to a base material 22 and an optical member 24. As shown in FIG. 2, the adhesive sheet 21 of the present invention is preferably used for bonding to the base material 22 and is preferably used for bonding the base material 22 and other optical members 24. Note that the adhesive sheet 21 of the present invention may be used for bonding to a polarizing plate.

[0111] In the laminate, when at least one adherend is an optical member, examples of the optical member include each component member in optical products such as touch panels and image display devices, and an anti-scattering film bonded to the outermost cover lens. Examples of the component 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, a transparent conductive film in which a conductive polymer is coated on a transparent resin film, a hard coat film, and a fingerprint-resistant film. Examples of the component members of the image display device include an anti-reflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device. Examples of the materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

[0112] Figure 3 is a schematic diagram showing a cross-section of another example of the laminate of the present invention. As shown in Figure 3, the adherend may have stepped portions (27a, 27b, 27c, 27d). In Figure 3, the base material has stepped portions (27a, 27b), and the optical member has stepped portions (27c, 27d). Note that the thickness of the stepped portions (27a, 27b, 27c, 27d) is usually 5 to 60 μm. Thus, the adhesive sheet 21 of the present invention can also be bonded to a member having stepped portions and can follow the unevenness generated from the stepped portions.

[0113] The manufacturing method of the laminate is not particularly limited. For example, a manufacturing method including, in this order, step 1 of laminating an adherend on at least one surface side of the pressure-sensitive adhesive sheet of the present invention, and 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 can be used to manufacture the laminate. Before irradiating with active energy rays, since the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is in a semi-cured state, the initial adhesion to the base material is good. Thus, after laminating the pressure-sensitive adhesive sheet on the adherend, post-curing the pressure-sensitive adhesive layer with active energy rays increases the cohesive force of the pressure-sensitive adhesive layer and improves the adhesiveness to the adherend. Also, the post-cured pressure-sensitive adhesive layer can prevent the base material from deforming or being distorted.

[0114] In the present invention, examples of the active energy rays include ultraviolet rays, electron beams, visible light rays, X-rays, ion beams, etc., and they can be appropriately selected according to the photoinitiator 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.

[0115] As the light source for 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, a electrodeless ultraviolet lamp, etc. can be used.

[0116] As the electron beam, for example, electron beams emitted from various types of electron beam accelerators such as a Cockcroft-Walton type, a Van de Graaff type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high-frequency type can be used.

[0117] The irradiation output of ultraviolet rays is preferably adjusted so that the integrated light quantity becomes 100 to 10000 mJ / cm 2 and more preferably so that it becomes 500 to 5000 mJ / cm 2

[0118] ​The method for manufacturing the laminate may further include a step of processing the laminate after the step 2. In this step, for example, various processes can be performed on the laminate, specifically, punching, cutting, and the like. The processing method is not particularly limited, and for example, known processing methods can be widely adopted.

Example

[0119] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the embodiments of these examples.

[0120] (Production Example 1: Synthesis of Crosslinkable Acrylic Copolymer (A-1)) As shown in the compounding table of Table 1, a crosslinkable acrylic copolymer (A-1) was prepared by a polymerization reaction of polymerizable monomers. More specifically, butyl acrylate monomer (hereinafter, "BA") as an alkyl (meth)acrylate ester having 3 or more carbon atoms in the alkyl group, methyl acrylate monomer (hereinafter, "MA") as an alkyl (meth)acrylate ester having 2 or less carbon atoms in the alkyl group, and acrylic acid (hereinafter, "AA") as a carboxy group-containing monomer were prepared, and a monomer mixture was prepared by mixing them so as to have the mass ratios (70:22:8) shown in Table 1, respectively. This monomer mixture was dissolved in ethyl acetate, and a polymerization reaction was carried out at 60°C in the presence of AIBN (azobisisobutyronitrile) as a radical polymerization initiator. Thereby, a crosslinkable acrylic copolymer (A-1) was obtained. In the obtained crosslinkable acrylic copolymer (A-1), the glass transition temperature (Tg) determined using the FOX equation was -33°C.

[0121] (Production Example 2: Synthesis of Crosslinkable Acrylic Copolymer (A-2)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, BA was used. As the (meth)acrylic acid alkyl ester with an alkyl group having 2 or less carbon atoms, ethyl acrylate monomer (hereinafter, "EA") was used. And as the carboxy group-containing monomer, AA was prepared. A crosslinkable acrylic copolymer (A-2) was obtained in the same manner as in Production Example 1 except that a monomer mixture was prepared by mixing them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (A-2), the glass transition temperature (Tg) determined using the FOX equation was -28°C.

[0122] (Production Example 3: Synthesis of crosslinkable acrylic copolymer (A-3)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, BA was used. As the (meth)acrylic acid alkyl ester with an alkyl group having 2 or less carbon atoms, methyl methacrylate monomer (hereinafter, "MMA") was used. And as the carboxy group-containing monomer, AA was prepared. 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 them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (A-3), the glass transition temperature (Tg) determined using the FOX equation was -25°C.

[0123] (Production Example 4: Synthesis of crosslinkable acrylic copolymer (A-4)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, BA was used. As the (meth)acrylic acid alkyl ester with an alkyl group having 2 or less carbon atoms, MA was used. And as the carboxy group-containing monomer, AA was prepared. A crosslinkable acrylic copolymer (A-4) was obtained in the same manner as in Production Example 1 except that a monomer mixture was prepared by mixing them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (A-2), the glass transition temperature (Tg) determined using the FOX equation was -26°C.

[0124] (Production Example 5: Synthesis of crosslinkable acrylic copolymer (a-1)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, BA was used. As the (meth)acrylic acid alkyl ester with an alkyl group having 2 or less carbon atoms, MA was used. And hydroxyethyl acrylate (hereinafter, "HEA") was prepared. A crosslinkable acrylic copolymer (a-1) was obtained in the same manner as in Production Example 1 except that a monomer mixture was prepared by mixing them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (a-1), the glass transition temperature (Tg) determined using the FOX equation was -39°C.

[0125] (Production Example 6: Synthesis of crosslinkable acrylic copolymer (a-2)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, 2-ethylhexyl acrylate (hereinafter, "2EHA") was used. And as the carboxyl group-containing monomer, AA was used. A crosslinkable acrylic copolymer (a-2) was obtained in the same manner as in Production Example 1 except that a monomer mixture was prepared by mixing them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (a-2), the glass transition temperature (Tg) determined using the FOX equation was -60°C.

[0126] (Production Example 7: Synthesis of crosslinkable acrylic copolymer (a-3)) As the (meth)acrylic acid alkyl ester with an alkyl group having 3 or more carbon atoms, BA was used. As the (meth)acrylic acid alkyl esters with an alkyl group having 2 or less carbon atoms, MA and MMA were used. And as the carboxyl group-containing monomer, AA was used. 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 them so as to have the mass ratios shown in Table 1 respectively. In the obtained crosslinkable acrylic copolymer (a-3), the glass transition temperature (Tg) determined using the FOX equation was -44°C.

[0127]

Table 1

[0128] (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), 0.1 part by mass of an epoxy compound (Tetrad X, manufactured by Mitsubishi Gas Chemical Company) as the crosslinking agent (denoted as epoxy in Table 2), 7 parts by mass of ethylene oxide-modified diacrylate (Aronix M211B, Tg = 75°C, manufactured by Toagosei Co., Ltd.) as the polyfunctional monomer (C), and 0.5 part by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (Omnirad184, manufactured by IGM Resins B.V.) as the photopolymerization initiator (D) were mixed, and ethyl acetate was added as a solvent so that the solid content concentration became 40% by mass to prepare an adhesive composition.

[0129] The above adhesive composition was applied onto a first release sheet (heavy separator film, a polyethylene terephthalate film subjected to a release treatment, manufactured by Teijin DuPont Films). The application was carried out using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. so that the thickness after drying would be 15 μm. Then, it was dried at 100°C for 3 minutes using a hot air dryer to remove the solvent, thereby forming an adhesive sheet having an adhesive layer in a semi-cured state.

[0130] A second release sheet (light separator film, manufactured by Teijin DuPont Films) having a higher releasability than the first release sheet was laminated on one side of this adhesive sheet to obtain an adhesive sheet which is an adhesive sheet with a release sheet.

[0131] (Example 2) An adhesive composition and an 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.

[0132] (Example 3) An adhesive composition and an 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 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.).

[0133] (Example 4) An adhesive composition and an 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.

[0134] (Example 5) An adhesive composition and an adhesive sheet with a release sheet were obtained 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).

[0135] (Example 6) An adhesive composition and an adhesive sheet with a release sheet were obtained 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 2, and the photopolymerization initiator (D) was changed to phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by BASF Japan Ltd., IRGACURE 819).

[0136] (Example 7) An adhesive composition and an adhesive sheet with a release sheet were obtained in the same manner as in Example 1, except that 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-trimethylbenzoyl)phosphine oxide (manufactured by BASF Japan Ltd., IRGACURE 819).

[0137] (Example 8) An adhesive composition and an adhesive sheet with a release sheet were obtained in the same manner as in Example 1, except that the crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (A-4) obtained in Production Example 4, the amount of the crosslinking agent (B) used was changed to 0.05 part by mass, and the photopolymerization initiator (D) was changed to phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by BASF Japan Ltd., IRGACURE 819).

[0138] (Comparative Example 1) An adhesive composition and an 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.

[0139] (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 30 parts by mass of polyethylene glycol #200 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-200, Tg = 50°C). An adhesive composition and an adhesive sheet with a release sheet were obtained in the same manner as in Example 1.

[0140] (Comparative Example 3) The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (a-1) obtained in Production Example 5, and the crosslinking agent (B) was changed to 0.2 part by mass of a xylylene diisocyanate compound (manufactured by Mitsui Chemicals, Inc., Takenate D-110N) (denoted as isocyanate in Table 2). An adhesive composition and an adhesive sheet with a release sheet were obtained in the same manner as in Example 1.

[0141] (Comparative Example 4) An adhesive composition and an adhesive sheet with a release sheet were obtained 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.

[0142] (Comparative Example 5) The crosslinkable acrylic copolymer (A) was changed to the crosslinkable acrylic copolymer (a-3) obtained in Production Example 7, the amount of the crosslinking agent (B) used was changed to 0.05 part by mass, 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 part by mass. An adhesive composition and an adhesive sheet with a release sheet were obtained in the same manner as in Example 1.

[0143] (Measurement and Evaluation) <Gel Fraction> The adhesive layer was cut to a size of 100 mm × 60 mm to prepare a measurement sample in a semi-cured state. Also, the adhesive layer was cut to a size of 100 mm × 60 mm, and ultraviolet light was irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated light quantity became 3000 mJ / cm 2 to prepare a measurement sample after post-curing.

[0144] Approximately 0.1 g of the adhesive sheet of the measurement sample in the semi-cured state and the measurement sample after post-curing (denoted as "before curing" and "after curing" in Table 2, respectively) were collected in a sample bottle, 30 ml of ethyl acetate was added, and the mixture was shaken for 24 hours. Then, the contents of this 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 (mass %) = (dry mass / collected mass of the adhesive sheet) × 100 ··· Formula 1 was used to determine the gel fraction.

[0145] <Adhesive force> The second release sheet, which is a light separator film of the adhesive layer, was peeled off, bonded to a PET film with 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 heavy separator film of the adhesive sheet, was peeled off, and a 2 kg roller was reciprocated to bond the adhesive surface of the adhesive sheet to the glass. The obtained sample with the structure of PET / adhesive layer / glass was subjected to autoclave treatment (40 °C, 0.5 MPa, 30 min), and then the other end of this sample was peeled off in the peeling direction of 180 degrees at a speed of 300 mm / min, and the adhesive force to the glass at that time (that is, the adhesive force of the adhesive layer in the semi-cured state; denoted as before curing in Table 2) was measured. On the other hand, a sample with the same structure of PET / adhesive layer / glass as described above was subjected to autoclave treatment (40 °C, 0.5 MPa, 30 min), and then ultraviolet light was irradiated from the PET film side so that the integrated light quantity became 3000 mJ / cm 2Irradiated it so as to obtain a test sample. In this test sample, the other end of the adhesive sheet was peeled in the peeling direction of 180 degrees at a speed of 300 mm / min, and the adhesive force to the glass at that time (that is, the adhesive force after the post-curing of the adhesive layer (in the post-cured state); in Table 2, denoted as after curing) was measured.

[0146] <Durability Test 1> The second release sheet, which is a light separator film of the adhesive layer, was peeled off and laminated on 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 adhered to a PC board with a thickness of 1 mm (a polycarbonate board without a hard coat layer: "Panlite PC1151" manufactured by Teijin). A sample having a structure of triacetyl cellulose film / adhesive layer / PC board was autoclaved (40 °C, 0.5 MPa, 30 min), and then ultraviolet rays were irradiated from the triacetyl cellulose film side so that the integrated light amount was 3000 mJ / cm 2 to obtain a test sample with a size of 100 mm × 200 mm. This test sample was allowed to stand still in an environment of 85 °C and a relative humidity of 85% for 240 hours respectively.

[0147] Thereafter, the test sample was observed, the presence or absence of errors (lifting 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: A part had an error of 1 mm or less. C: An error exceeding 1 mm was confirmed.

[0148] <Durability Test 2> The durability was evaluated in the same method and criteria as in Durability Test 1 except that the thickness of the PC board was changed to 2 mm.

[0149] <Processability> The second release sheet, which is a light separator film of the adhesive layer, was peeled off and laminated on a PET film with a thickness of 25 μm. Next, the first release sheet, which is a heavy separator film, was peeled off and adhered to a PC board. The sample having the structure of PET / adhesive layer / PC thus obtained was subjected to autoclave treatment (40 °C, 0.5 MPa, 30 min), and then ultraviolet rays were irradiated from the PET film side so that the integrated light amount became 3000 mJ / cm 2 to obtain a test sample. Next, the end portion of the test sample was cut using a guillotine cutter, and the cut end portion was rubbed by hand from the PC board side to peel off the PET film. The processability was evaluated by measuring the peeling distance at that time. A: The peeling distance was less than 0.05 mm, indicating excellent processability. 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.

[0150]

Table 2

[0151] Table 2 also shows the results of each evaluation in addition to the production conditions of the adhesive sheets of the above-described examples and comparative examples. From this Table 2, it was shown that the adhesive sheets obtained in the examples had high adhesive strength, excellent blister resistance, were less likely to float or peel from the adherend even in a high-temperature and high-humidity environment, and were excellent in adhesion and durability. In addition, the adhesive sheets of the examples had good processability. On the other hand, the adhesive sheets of the comparative examples had inappropriate one or more of the Tg of the crosslinkable acrylic copolymer, the content ratio of the acidic functional group in the crosslinkable acrylic copolymer, and the amount of the polyfunctional monomer used, so the substrate adhesion (adhesive strength) and durability were inferior.

Claims

1. An adhesive sheet comprising an adhesive layer containing 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) having two or more polymerizable double bonds in the molecule, and a photopolymerization initiator (D); the crosslinking agent (B) is at least one epoxy compound selected from the group consisting of ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidyl xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether; the crosslinkable acrylic copolymer (A) contains a non-crosslinkable (meth)acrylate unit (a1) and a structural unit (a2) having an acidic functional group; the non-crosslinkable (meth)acrylate unit (a1) includes both a (meth)acrylate alkyl ester in which the alkyl group in the alkyl ester has 2 or less carbon atoms and a (meth)acrylate alkyl ester in which the alkyl group has 3 or more carbon atoms; the content ratio of the structural unit (a2) is 5 to 15% by mass based on all the structural units contained in the crosslinkable acrylic copolymer (A); the glass transition temperature of the crosslinkable acrylic copolymer (A) is -35 to -25°C; the polyfunctional monomer (C) is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the crosslinkable acrylic copolymer (A), an adhesive sheet.

2. the gel fraction of the adhesive layer is 50 to 80%, and The gel fraction is 75 to 90% when the pressure-sensitive adhesive layer is irradiated with active energy rays so that the integrated light quantity is 3000 mJ / cm ２ The pressure-sensitive adhesive sheet according to claim 1.

3. the adhesive strength of the adhesive layer is 5 N / 25 mm or more, and When the adhesive layer is irradiated with active energy rays so that the integrated light quantity is 3000 mJ / cm ２ The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the adhesive force when post-cured is 10 N / 25 mm or more.

4. An adhesive sheet with a release sheet, comprising a pair of release sheets having different release forces on both sides of the adhesive sheet according to any one of Claims 1 to 3.

5. An adhesive sheet according to any one of Claims 1 to 3, and an adherend provided on at least one surface side of the adhesive sheet, wherein the adhesive layer of the adhesive sheet is in a post-cured state, a laminate.

6. The laminate according to Claim 5, wherein the adherend is one or more selected from the group consisting of a resin plate and a resin film.

7. Step 1 of laminating an adherend on at least one surface side of the pressure-sensitive adhesive sheet according to any one of claims 1 to 3, and A method for manufacturing a laminate, comprising 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.

8. The method for manufacturing a laminate according to claim 7, further comprising a step of processing the laminate after Step 2.

9. The method for manufacturing a laminate according to claim 7 or 8, wherein the thickness of the pressure-sensitive adhesive layer is 5 to 150 μm.

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