Adhesive Composition, Adhesive Layer, and Adhesive Sheet

Abstract

To provide an adhesive sheet that shows sufficient initial adhesiveness to an adherend in a wet condition and high adhesion power and can suppress corrosion of the adherend.SOLUTION: The present invention relates to an adhesive composition including a base polymer, wherein the base polymer is a copolymer including structures derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogenous hydrophilic monomer and the base polymer has a content of structures derived from the water-insoluble hydrophilic monomer (a) of 40 mass% or higher.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive layer, and an adhesive sheet.

Background Art

[0002] Conventionally, adhesives and pressure-sensitive adhesives have been used for adhesion and fixation in various fields, and development has been underway for materials that can exhibit sufficient adhesive strength and tackiness even for adherends in a wet state where it is difficult to obtain adhesive strength.

[0003] For example, Patent Document 1 describes a pressure-sensitive adhesive that rapidly adheres to a wet or dry substrate surface and contains a polymerization product of a (meth)acrylate ester monomer, a hydrophilic acidic comonomer, and a non-reactive plasticizer, and a method for producing the same. Patent Document 2 describes an adhesive sheet that covers the surface of a cementitious material such as concrete, mortar, or cement, and has an adhesive containing a polymer derived from a monomer component containing an alkyl (meth)acrylate having 4 to 18 carbon atoms and a monomer having at least one nitrogen-containing functional group, wherein the adhesive layer can adhere to the surface of the cementitious material in a wet state and can be peeled off from the surface of the cured cementitious material. Furthermore, in the manufacturing process of electronic components and electronic devices, etc., an adhesive sheet may be used for protecting members, and this adhesive sheet may be used after the electronic components and electronic devices are washed with water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, since a hydrophilic acidic comonomer is used, it causes corrosion when used in concrete or the like. Further, when used in the manufacture of electronic components such as printed wiring boards and electronic devices, there is a risk that the adherend will be affected by the acid. Furthermore, when used after washing electronic components and electronic devices with water, a drying process is required. And in the conventional technology, there are problems such as insufficient initial adhesiveness to an adherend with a high water content or an adherend in a state of being wet with water, and poor workability. There is a demand for the development of an adhesive sheet that exhibits sufficient adhesive force to a wet adherend.

[0006] Therefore, an object of the present invention is to provide an adhesive sheet that suppresses corrosion of an adherend, exhibits sufficient initial adhesiveness and high adhesive force to a wet adherend, an adhesive composition capable of producing the adhesive sheet, and an adhesive layer.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved, and the present invention has been completed. That is, the present invention is as follows.

[0008] 〔1〕 An adhesive composition containing a base polymer, wherein the base polymer is a copolymer containing structures derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer, and the content ratio of the structure derived from the (a) water-insoluble hydrophilic monomer in the base polymer is 40% by mass or more. 〔2〕 An adhesive composition containing a base polymer, wherein the adhesive layer formed by the adhesive composition has a water absorption of 9.0 mg or more measured by the following method. Method for measuring water absorption: A measurement sample obtained by attaching the adhesive layer with a thickness of 100 μm to a PET film with a thickness of 50 μm and cutting it into 2.5 cm × 5 cm is calculated from the difference between the mass after immersion in pure water under the following conditions and the mass before immersion. Immersion temperature: 23 °C Immersion time: 5 minutes 〔3〕 The adhesive composition according to 〔1〕, wherein the (a) water-insoluble hydrophilic monomer is at least one selected from methoxyethyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-dipropylene glycol acrylate, and methoxy-triethylene glycol acrylate. 〔4〕 The adhesive composition according to 〔1〕 or 〔3〕, wherein the (b) nitrogen-containing hydrophilic monomer is at least one selected from N-vinyl-2-pyrrolidone, hydroxyethyl acrylamide, acryloylmorpholine, vinylformamide, and vinylacetamide. 〔5〕 The adhesive composition according to any one of 〔1〕 to 〔4〕, further containing a crosslinking agent, wherein the crosslinking agent is at least one selected from a photocuring agent or an isocyanate compound. 〔6〕 The adhesive composition according to 〔5〕, wherein the photocuring agent is a photocurable monomer or a photocurable oligomer. 〔7〕 An adhesive layer comprising the adhesive composition according to any one of 〔1〕 to 〔6〕. 〔8〕 The swelling degree after immersion in water at 5 °C for 24 hours is 2.5 to 10, The swelling degree after immersion in water at 23 °C for 24 hours is 1.0 to 2.5. The adhesive layer according to 〔7〕. 〔9〕 An adhesive sheet comprising the adhesive layer according to 〔7〕 or 〔8〕. 〔10〕 The adhesive sheet according to 〔9〕, wherein the adhesive layer is formed on a substrate.

Advantages of the Invention

[0009] According to the present invention, there can be provided an adhesive sheet that exhibits sufficient initial adhesiveness to a wet adherend, shows a high adhesive force, and can suppress corrosion of the adherend, an adhesive composition capable of producing the adhesive sheet, and an adhesive layer.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011] Hereinafter, modes for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

[0012] 〔Adhesive Composition〕 The adhesive composition according to an embodiment of the present invention is an adhesive composition containing a base polymer, wherein the base polymer is a copolymer containing a structure derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer, and the content ratio of the structure derived from the (a) water-insoluble hydrophilic monomer in the base polymer is 40% by mass or more. The adhesive composition according to another embodiment of the present invention is an adhesive composition containing a base polymer, The adhesive layer formed by the adhesive composition has a water absorption of 9.0 mg or more as measured by the following method. Method for measuring water absorption: A measurement sample obtained by attaching the adhesive layer having a thickness of 100 μm to a PET film having a thickness of 50 μm and cutting it into 2.5 cm × 5 cm is calculated from the difference between the mass after immersion in pure water under the following conditions and the mass before immersion. Immersion temperature: 23°C Immersion time: 5 minutes

[0013] (Base polymer) The base polymer in the pressure-sensitive adhesive composition according to this embodiment refers to the main component of the polymer contained in the pressure-sensitive adhesive composition. Also, in this specification, the "main component" refers to a component contained in an amount exceeding 50% by mass unless otherwise specified.

[0014] The base polymer used in the pressure-sensitive adhesive composition according to this embodiment may be a temperature-responsive polymer. A temperature-responsive polymer refers to a polymer that causes reversible changes such as dissolution / insolubility and hydrophilicity / hydrophobicity due to temperature changes. Among them, it is preferable that the polymer changes its solubility in water due to temperature changes, dissolves in water at low temperatures, but becomes insoluble and turbid / precipitates when heated to a certain temperature (for example, the lower critical solution temperature: LCST). By adjusting the type and blending ratio of the monomers used for the base polymer, it is possible to obtain a temperature-responsive polymer.

[0015] The base polymer contained in the pressure-sensitive adhesive composition according to the embodiment of the present invention contains a structure derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer, and the content ratio of the structure derived from the (a) water-insoluble hydrophilic monomer in the base polymer is 40% by mass or more. The base polymer may be a polymer containing a structure derived from a water-insoluble hydrophilic monomer and a nitrogen-containing hydrophilic monomer, or may be a copolymer of (c) other monomer components and (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer. Also, a mixture of a polymer containing a structure derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer and a known polymer composed of (c) other monomers may be used as the base polymer. The base polymer contains structures derived from (a) a water-insoluble hydrophilic monomer and (b) a nitrogen-containing hydrophilic monomer, and the content ratio of the structure derived from the (a) water-insoluble hydrophilic monomer in the base polymer is 40% by mass or more, so that the water absorption of the pressure-sensitive adhesive composition is good, and when the pressure-sensitive adhesive sheet is applied to an adherend in a wet state, there is an effect of absorbing and removing the remaining moisture that inhibits adhesion.

[0016] (a) Water-insoluble hydrophilic monomer (a) The water-insoluble hydrophilic monomer refers to a monomer that separates into an aqueous phase and an oil phase when the monomer is mixed with water. The water-insoluble hydrophilic monomer according to the present embodiment preferably has a hydrophilic group. Examples of the hydrophilic group include alkoxy groups such as methoxy group and ethoxy group, hydroxy group, amine group, carboxylic acid group and the like. In the base polymer according to the embodiment of the present invention, the content ratio of the structure derived from the (a) water-insoluble hydrophilic monomer needs to be 40% by mass or more, and it is preferable to use the (a) water-insoluble hydrophilic monomer as the main monomer constituting the base polymer. When the base polymer contains the (a) water-insoluble hydrophilic monomer as the main monomer, there is an effect of suppressing swelling and dissolution in water. Further, the main monomer is preferably a low-Tg monomer. When the content of the low-Tg monomer in the base polymer is large, the storage elastic modulus G' tends to decrease and adhesiveness tends to be exhibited. The low-Tg monomer means a monomer having a low glass transition temperature (Tg) of the homopolymer. The low-Tg monomer preferably has a Tg in the range of -70°C to 0°C.

[0017] As the (a) water-insoluble hydrophilic monomer according to the present embodiment, a hydrophilic (meth)acrylate is preferable. The hydrophilic (meth)acrylate ester according to this embodiment is a (meth)acrylate ester having a hydrophilic ester residue, and it may be a single kind thereof, or may contain two or more kinds. As the hydrophilic (meth)acrylate ester, it is preferably at least one selected from the group consisting of (meth)acrylate alkoxyalkyl esters, (meth)acrylate polyalkylene glycol esters, (meth)acrylate hydroxyalkyl esters, and (meth)acrylate hydroxyaralkyl esters.

[0018] Specifically, examples thereof include (meth)acrylate alkoxyalkyl esters such as methoxyethyl acrylate (MEA) and ethoxyethoxyethyl acrylate (EEEA). In addition, as the (meth)acrylate polyalkylene glycol ester, the formula: CH2=CR 1 -CO-(O-CH2CHR 2 )n-OR 3 (wherein, R 1 and R 2 : each independently a hydrogen atom or a methyl group, R 3 : an alkyl group having 1 to 20 carbon atoms, n: an integer of 1 to 12), such as methoxypolyethylene glycol (meth)acrylate or methoxypolypropylene glycol (meth)acrylate. Preferred hydrophilic (meth)acrylate esters are (meth)acrylate alkoxyalkyl esters having an alkoxy group having 1 to 4 carbon atoms, or (meth)acrylate methoxypolyethylene glycol.

[0019] More specifically, it is preferably at least one selected from methoxyethyl acrylate (MEA), ethoxy-diethylene glycol acrylate (ethoxy-diethylene glycol acrylate), methoxy-dipropylene glycol acrylate (methoxy-dipropylene glycol acrylate), and methoxy-triethylene glycol acrylate (methoxy-triethylene glycol acrylate), and more preferably methoxyethyl acrylate (MEA).

[0020] Among all the monomer components constituting the base polymer, it is preferable to use (a) a water-insoluble hydrophilic monomer as the main monomer. From the viewpoint of suppressing swelling and dissolution in water, the content ratio of (a) the water-insoluble hydrophilic monomer needs to be 40% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 75% by mass or more. Also, from the viewpoint of adhesiveness to the wet surface, it is preferably 99% by mass or less, more preferably 95% by mass or less, and still more preferably 90% by mass or less.

[0021] (b) Nitrogen-containing hydrophilic monomer The (b) nitrogen-containing hydrophilic monomer according to the present embodiment refers to a monomer containing a nitrogen atom and a hydrophilic group. Examples of the hydrophilic group include a carboxylic acid group, a hydroxy group, an amine group, etc. The homopolymer of the (b) nitrogen-containing hydrophilic monomer is preferably water-soluble, and preferably has a mass increase of 5% or more after standing for 1 day in a humid environment at 40 °C and 92%.

[0022] (b) The nitrogen-containing hydrophilic monomer dissolves in water without separating into an oil layer and a water layer, and can be a water-absorbing component in the base polymer according to the embodiment of the present invention. Here, the water-absorbing component represents a component that can absorb and hold moisture. When the base polymer contains a water-absorbing component, Adhesive sheet when it is attached to the wet surface of the adherend, the water-absorbing component contained in the adhesive layer Adhesive sheet absorbs and holds the moisture on the wet surface that hinders the adhesion between the adherend and the adherend, thereby Adhesive sheet the initial adhesive force to the adherend becomes good. Also, since the moisture on the wet surface of the adherend is absorbed and removed by the water-absorbing component, the initial adhesiveness to the wet surface is more likely to be improved.

[0023] Further, the nitrogen-containing hydrophilic monomer (b) according to the present embodiment is preferably a water-soluble monomer. For example, dialkyl (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, monoalkyl (meth)acrylamides such as N-isopropyl (meth)acrylamide, alkoxydiacetone acrylamide, hydroxyethyl acrylamide (HEAA), acryloylmorpholine (ACMO), nitrogen-containing water-soluble monomers such as N-vinyl-2-pyrrolidone (NVP), vinylformamide (NVF), N-vinylacetamide (NVA), etc. may be mentioned. Note that these may be used alone as only one kind, or in combination of two or more kinds. The nitrogen-containing hydrophilic monomer (b) is preferably at least one selected from N-vinyl-2-pyrrolidone, hydroxyethyl acrylamide, acryloylmorpholine, vinylformamide, and vinylacetamide.

[0024] From the viewpoint of adhesion to a wet surface, the content ratio of the nitrogen-containing hydrophilic monomer (b) in all monomer components constituting the base polymer is preferably 1% by mass or more, more preferably 2.5% by mass or more, and even more preferably 5% by mass or more. Further, from the viewpoint of suppressing swelling and dissolution in water, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0025] (c) Other monomers The (c) other monomers other than the (a) water-insoluble hydrophilic monomer and the (b) nitrogen-containing hydrophilic monomer are not particularly limited, and monomers corresponding to known polymers used in adhesives can be used. When the base polymer contains the (c) other monomers, there is an effect of improving the cohesive force due to crosslinking of the polymer.

[0026] Examples of the (c) other monomers include hydroxyl group-containing monomers. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; polypropylene glycol mono (meth) acrylate; N-hydroxyethyl (meth) acrylamide and the like. Among them, preferred hydroxyl group-containing monomers include hydroxyalkyl (meth) acrylates in which the alkyl group is a straight chain having 2 to 4 carbon atoms, and 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA) are preferred.

[0027] (c) As other monomers, water-insoluble hydrophobic monomers are further included. Examples of the water-insoluble hydrophobic monomers include (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters (alkyl (meth)acrylic acid esters having a linear or branched alkyl group). Examples of the above (meth)acrylic acid alkyl esters include (meth)acrylic acid methyl, (meth)acrylic acid ethyl, (meth)acrylic acid propyl, (meth)acrylic acid isopropyl, (meth)acrylic acid n-butyl, (meth)acrylic acid isobutyl, (meth)acrylic acid s-butyl, (meth)acrylic acid t-butyl, (meth)acrylic acid pentyl, (meth)acrylic acid isopentyl, (meth)acrylic acid hexyl, (meth)acrylic acid heptyl, (meth)acrylic acid octyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid nonyl, (meth)acrylic acid isononyl, (meth)acrylic acid decyl, (meth)acrylic acid isodecyl, (meth)acrylic acid undecyl, (meth)acrylic acid dodecyl, (meth)acrylic acid tridecyl, (meth)acrylic acid tetradecyl, (meth)acrylic acid pentadecyl, (meth)acrylic acid hexadecyl, (meth)acrylic acid heptadecyl, (meth)acrylic acid octadecyl, (meth)acrylic acid nonadecyl, (meth)acrylic acid eicosyl and the like, which are (meth)acrylic acid alkyl esters having an alkyl group with 1 to 20 carbon atoms. Among them, (meth)acrylic acid alkyl esters having an alkyl group with 1 to 14 carbon atoms are preferable, and (meth)acrylic acid alkyl esters having an alkyl group with 2 to 10 carbon atoms are more preferable. Note that the above "(meth)acrylic acid ester" represents "acrylic acid ester" and / or "methacrylic acid ester", and the same applies to others.

[0028] In addition, examples of (meth)acrylic acid esters other than the above (meth)acrylic acid alkyl esters include (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and (meth)acrylic acid esters having an aromatic hydrocarbon group such as phenyl (meth)acrylate.

[0029] The above (meth)acrylic acid ester can be used alone or in combination of two or more. Further, as long as it is a monomer having no polar functional group, a monomer other than the acrylic monomer may be copolymerized with the (meth)acrylic acid ester.

[0030] In the present embodiment, among the (meth)acrylic acid esters, it is preferable that 80% by mass or more is an alkyl (meth)acrylate, more preferably 90% by mass or more, and still more preferably 100% by mass.

[0031] The content ratio of (c) other monomers (preferably monomers containing a hydroxyl group) in all the monomer components constituting the base polymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and still more preferably 2% by mass or more from the viewpoint of the number of crosslinking points of the polymer. Further, from the viewpoint of preventing gelation of the pressure-sensitive adhesive, it is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. In addition, the content ratio of the water-insoluble hydrophobic monomer as (c) other monomers in all the monomer components constituting the base polymer is preferably 45% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less from the viewpoint of absorbing moisture on the wet surface.

[0032] (Other polymers) In addition, the pressure-sensitive adhesive composition may contain a known polymer such as a modifier (hereinafter also referred to as other polymers) in addition to the above-described base polymer as long as the effects of the present invention are not significantly inhibited. In that case, the content ratio of the other polymer with respect to the entire base polymer (100% by mass) is preferably 75% by mass or less, and more preferably 60% by mass or less.

[0033] (Crosslinking agent) The pressure-sensitive adhesive composition according to an embodiment of the present invention preferably further contains a crosslinking agent. By introducing a crosslinked structure into the base polymer, an appropriate cohesive force can be imparted to the pressure-sensitive adhesive layer, and residue of the adhesive at the time of peeling of the pressure-sensitive adhesive can be prevented. For example, by adding a crosslinking agent to the solution after polymerization of the base polymer and performing irradiation with active light or heating as necessary, a crosslinked structure is introduced and crosslinking proceeds. Examples of the crosslinking agent include photocuring agents such as photocurable monomers and photocurable oligomers, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, and metal chelate-based crosslinking agents. These crosslinking agents react with functional groups such as hydroxy groups and carboxy groups introduced into the base polymer to form a crosslinked structure. Since they have high reactivity with the hydroxy groups and carboxy groups of the base polymer and it is easy to introduce a crosslinked structure, a photocurable monomer, a photocurable oligomer, or an isocyanate-based crosslinking agent is preferred as the crosslinking agent. From the viewpoint of increasing the thickness of the pressure-sensitive adhesive layer, it is preferable to use a photocuring agent. Note that only one type of crosslinking agent may be used alone, or two or more types may be used in combination.

[0034] As the photocuring agent, a photocurable monomer or a photocurable oligomer is preferably used. As the photocuring agent, a compound having two or more ethylenically unsaturated bonds in one molecule is preferable. Further, the photocuring agent is preferably a compound that shows compatibility with the base polymer. Since it shows appropriate compatibility with the base polymer, the photocuring agent is preferably liquid at room temperature. When the photocuring agent is compatible with the base polymer and is uniformly dispersed in the composition, it becomes possible to secure the contact area with the adherend. Further, since the base polymer and the photocuring agent show appropriate compatibility, a photo-crosslinked structure can be uniformly introduced into the pressure-sensitive adhesive layer. When the photocurable pressure-sensitive adhesive composition containing a photocuring agent in addition to the base polymer is photocured, the crosslinked structure of the pressure-sensitive adhesive is formed, so that the cohesive force of the polymer is improved and the adhesive force to the adherend is improved.

[0035] For improving the cohesive force of the polymer, it is preferable to use a polyfunctional (meth)acrylate as a photoinitiator. Examples of the polyfunctional (meth)acrylate include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, bisphenol A ethylene oxide-modified di(meth)acrylate, bisphenol A propylene oxide-modified di(meth)acrylate, alkane diol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, dipentaerythritol hexa(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin di(meth)acrylate, urethane (meth)acrylate, epoxy (meth)acrylate, butadiene (meth)acrylate, isoprene (meth)acrylate, etc. Among them, alkane diol di(meth)acrylate is preferable, and hexanediol diacrylate (HDDA) and trimethylolpropane tri(meth)acrylate (TMPTA) are more preferable.

[0036] Since the photocurable compound is included in the pressure-sensitive adhesive composition as an uncured monomer or oligomer, a photocurable pressure-sensitive adhesive layer can be obtained. In order to include the photoinitiator in the composition in an uncured state, it is preferable to add the photoinitiator to the polymer solution after polymerization of the base polymer.

[0037] The compatibility between the base polymer and the photoinitiator is also affected by the molecular weight of the compound. The smaller the molecular weight of the photocurable compound, the higher the compatibility with the base polymer tends to be. From the viewpoint of compatibility with the base polymer, the molecular weight of the photoinitiator is preferably 1500 or less, and more preferably 1000 or less.

[0038] The crosslinking agent in this embodiment may be an isocyanate compound. Isocyanate compounds (isocyanates) are hydrolyzed in the presence of water to form amines, and the isocyanates and amines react to form urea bonds, thereby curing. In addition, chemical bonds can be formed with hydroxyl groups, amino groups, carboxyl groups, etc. on the surface of the adherend.

[0039] Examples of isocyanate compounds include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates. Among them, aliphatic isocyanates and alicyclic isocyanates are preferred because they have good compatibility with base polymers, especially rubber-based polymers, and have moderate reactivity with moisture and water.

[0040] Examples of aliphatic isocyanates include ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHMDI), dodecamethylene diisocyanate, lysine diisocyanate (LDI), lysine triisocyanate (LTI), etc. Among them, hexamethylene diisocyanate is preferred.

[0041] Examples of alicyclic isocyanates include isophorone diisocyanate (IPDI), cyclohexylene diisocyanate (CHDI), 4,4'-dicyclohexylmethane diisocyanate, hydrogenated XDI (H6XDI), hydrogenated MDI (H 12 MDI), norbornene diisocyanate (NBDI), etc.

[0042] Examples of the aromatic isocyanate include diphenylmethane diisocyanate (MDI) such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate; crude diphenylmethane diisocyanate; polynuclear polyphenylene polymethyl polyisocyanate (polymeric MDI); tolylene diisocyanate (TDI) such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; naphthalene diisocyanate (NDI) such as 1,4-naphthalene diisocyanate and 1,5-naphthalene diisocyanate; 1,5-tetrahydronaphthalene diisocyanate; phenylene diisocyanate (PDI) such as 1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene diisocyanate; xylylene diisocyanate (XDI); tetramethylxylylene diisocyanate (TMXDI); tolidine diisocyanate (TODI); 2,4,6-trimethylphenyl-1,3-diisocyanate, 2,4,6-triisopropylphenyl-1,3-diisocyanate, chlorophenylene-2,4-diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-phenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, and trimethylolpropane adduct of tolylene diisocyanate, etc.

[0043] The content of the crosslinking agent in the pressure-sensitive adhesive composition in the present embodiment is not particularly limited. From the viewpoint of obtaining high adhesive strength, it is preferably 0.005 parts by mass or more, more preferably 0.0075 parts by mass or more, and still more preferably 0.01 parts by mass or more with respect to 100 parts by mass of the monomer constituting the base polymer. Further, from the viewpoint of suppressing the increase in the storage elastic modulus due to crosslinking, it is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, and still more preferably 0.1 part by mass or less. Incidentally, the preferable range of the content of the crosslinking agent with respect to 100 parts by mass of the base polymer in the pressure-sensitive adhesive layer is substantially the same as the preferable range of the content of the crosslinking agent with respect to 100 parts by mass of the monomer constituting the base polymer in the pressure-sensitive adhesive composition, and the same applies to other components that can be contained in the pressure-sensitive adhesive composition (pressure-sensitive adhesive layer).

[0044] The pressure-sensitive adhesive composition according to this embodiment may contain a tackifier (adhesion-imparting agent) for the purpose of adjusting the elastic modulus and imparting tack during initial adhesion. Examples of the tackifier include polybutenes, rosin resins, terpene resins, petroleum resins (e.g., petroleum aliphatic hydrocarbon resins, petroleum aromatic hydrocarbon resins, petroleum aliphatic-aromatic copolymer hydrocarbon resins, petroleum alicyclic hydrocarbon resins (hydrogenated aromatic hydrocarbon resins), etc.), coumarone resins, and the like. From the viewpoint of compatibility with the base polymer, petroleum resins and rosin resins are preferable. The tackifier may be used alone or in combination of two or more.

[0045] When the pressure-sensitive adhesive composition contains a tackifier, the content is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more with respect to 100 parts by mass of the base polymer from the viewpoint of reducing the elastic modulus. Also, the content of the tackifier is preferably 500 parts by mass or less, more preferably 400 parts by mass or less, and even more preferably 250 parts by mass or less with respect to 100 parts by mass of the base polymer from the viewpoint of giving the pressure-sensitive adhesive appropriate cohesive force.

[0046] In addition, additives usually added to the pressure-sensitive adhesive composition, such as a polymerization initiator, a viscosity modifier, a release modifier, a plasticizer, a softening agent, a filler, a coloring agent (pigment, dye, etc.), an antioxidant, a surfactant, a leveling agent, an antifoaming agent, a light stabilizer, etc., may be further added to the pressure-sensitive adhesive composition of this embodiment as long as the effects of the present invention are not inhibited.

[0047] Examples of the polymerization initiator include azo compounds, benzoin ethers, benzyl ketals, acetophenones, and alkylphenones. 、 Examples of the monoacylphosphine oxides include bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. Alkylphenone-based photoinitiators are preferred, and 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, (2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one are more preferred. Examples of the commercially available products include Irgacure 127, 184, 369, 651, 500, 891, 907, 2959, Darocure 1173, and TPO (manufactured by BASF Japan Ltd., trade name). The polymerization initiator may be used alone or in combination of two or more.

[0048] The polymerization initiator is preferably 0.01 part by mass or more, more preferably 0.025 part by mass or more, and even more preferably 0.05 part by mass or more with respect to 100 parts by mass of the monomer contained in the pressure-sensitive adhesive composition. From the viewpoint of the molecular weight of the obtained polymer, it is preferably 1 part by mass or less, more preferably 0.5 part by mass or less, and even more preferably 0.25 part by mass or less.

[0049] Examples of the filler include inorganic fillers such as talc, titanium oxide, calcium oxide, magnesium oxide, zinc oxide, titanium oxide, calcium carbonate, carbon, silica, clay, mica, barium sulfate, whisker, and magnesium hydroxide. From the viewpoint of the rough surface adhesiveness, the content of the filler is preferably 500 parts by mass or less, more preferably 300 parts by mass or less with respect to 100 parts by mass of the base polymer.

[0050] In addition, as the solvent used in the pressure-sensitive adhesive composition, various general solvents can be used. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvents may be used alone or in combination of two or more.

[0051] The pressure-sensitive adhesive composition according to this embodiment preferably has a Young's modulus at 25°C of the pressure-sensitive adhesive layer of 0.1 kPa or more, more preferably 1 kPa or more, still more preferably 5 kPa or more, and particularly preferably 10 kPa or more when the pressure-sensitive adhesive layer is formed. If the Young's modulus is 0.1 kPa or more, deformation of the pressure-sensitive adhesive layer is less likely to occur, and the shape stability of the pressure-sensitive adhesive sheet is good. In addition, defects such as paste oozing due to stress applied after adhesion are less likely to occur. From the viewpoint of adhesion to a wet surface, the Young's modulus is preferably 400 kPa or less, preferably 200 kPa or less, and more preferably 100 kPa or less. If the Young's modulus is 400 kPa or less, good adhesive strength can be exhibited even on a wet adherend, and excellent water resistance can be demonstrated.

[0052] Here, the Young's modulus of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is formed can be calculated from the stress-strain curve measured when a sample in which the pressure-sensitive adhesive layer is formed in a string shape is prepared and pulled at a speed of 50 mm / min using a tensile testing machine (AG-IS manufactured by Shimadzu Corporation).

[0053] 〔Pressure-sensitive adhesive layer〕 The pressure-sensitive adhesive layer according to the embodiment of the present invention can be formed by the above pressure-sensitive adhesive composition. The pressure-sensitive adhesive layer according to the embodiment of the present invention preferably has a water absorption of 9.0 mg or more as measured by the following method. Method for measuring water absorption: A measurement sample obtained by attaching the adhesive layer with a thickness of 100 μm to a PET film with a thickness of 50 μm and cutting it into 2.5 cm × 5 cm is calculated from the difference between the mass after immersion in pure water under the following conditions and the mass before immersion. Immersion temperature: 23 °C Immersion time: 5 minutes

[0054] By setting the water absorption of the adhesive layer according to the embodiment of the present invention to 9.0 mg or more, Adhesive sheet when it is attached to the wet surface of the adherend, the adhesive layer Adhesive sheet absorbs and retains the moisture on the wet surface that hinders the adhesion between the adhesive layer and the adherend, Adhesive sheet the initial adhesive strength to the adherend is good. In addition, since the moisture on the wet surface of the adherend is absorbed and removed, the initial adhesiveness to the wet surface is more likely to be improved.

[0055] The adhesive layer according to this embodiment preferably has a water absorption of 9.0 mg or more, more preferably 15 mg or more, even more preferably 17.5 mg or more, and still more preferably 20 mg or more. Also, from the viewpoint of swelling during immersion in water, it is preferably 50 mg or less, more preferably 45 mg or less, and even more preferably 40 mg or less.

[0056] In addition, the adhesive layer according to the embodiment of the present invention preferably has temperature responsiveness. Specifically, the swelling degree of the adhesive layer after immersion in water at 5 °C for 24 hours is preferably 2.5 or more, more preferably 3 or more, and even more preferably 5 or more. Also, it is preferably 10 or less, more preferably 9 or less, and even more preferably 7.5 or less. The swelling degree of the adhesive layer after immersion in water at 23 °C for 24 hours is preferably 1.0 or more, more preferably 1.1 or more, and even more preferably 1.5 or more. Also, it is preferably 2.5 or less, more preferably 2.25 or less, and even more preferably 2 or less.

[0057] The adhesive layer preferably has a swelling degree of 2.5 to 10 after being immersed in water at 5°C for 24 hours and a swelling degree of 1.0 to 2.5 after being immersed in water at 23°C for 24 hours. The swelling degree can be calculated by the following formula. Swelling degree = (mass after 24-hour immersion / initial mass) × 100

[0058] By using a temperature-responsive polymer as the base polymer used in the adhesive composition according to this embodiment, temperature responsiveness can be imparted to the adhesive layer according to the embodiment of the present invention.

[0059] The adhesive layer in this embodiment is formed using the above adhesive composition. The forming method is not particularly limited, and known methods can be adopted. For example, the adhesive composition can be applied to a base material described later using a known coating method and dried to obtain it in the form of an adhesive sheet. Note that the preferable range of the amount of each component in the adhesive layer is the same as the preferable range of the amount of each component excluding the solvent in the adhesive composition.

[0060] Also, the adhesive layer may be formed by applying the adhesive composition to a release liner (which may be a sheet-like base material having a release surface). After forming the adhesive layer by applying the adhesive composition to a surface having releasability and drying or curing it, the adhesive layer may be bonded to a non-releasable base material and transferred.

[0061] The method of applying the adhesive composition to the base material is not particularly limited, and for example, it can be carried out using a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a fountain die coater, a closed edge die coater, etc. The adhesive composition is applied onto the base material, and the solvent is dried and removed as necessary to form the adhesive layer. As the drying method, an appropriate method can be adopted as appropriate. The drying temperature can be, for example, 50 to 150°C. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 15 minutes, and even more preferably 10 seconds to 10 minutes.

[0062] When the adhesive composition contains a crosslinking agent, it is preferable to cure the adhesive layer by advancing crosslinking by irradiating active light, heating, or aging simultaneously with or after drying the solvent.

[0063] Examples of the active light include ultraviolet rays, visible light, infrared rays, X-rays, α-rays, β-rays, and γ-rays. Since it is possible to suppress the curing of the adhesive layer in the storage state and the curing is easy, ultraviolet rays are preferable as the active light. The irradiation intensity and irradiation time of the active light may be appropriately set according to the composition and thickness of the adhesive layer.

[0064] The heating temperature and heating time are appropriately set according to the type of crosslinking agent used, and usually, crosslinking is carried out by heating in the range of 20°C to 160°C for about 1 minute to 7 days. The heating for drying and removing the solvent may also serve as the heating for crosslinking.

[0065] The thickness of the adhesive layer after drying is not particularly limited, but from the viewpoint of exhibiting good adhesive strength to the adherend, it is preferably 5 to 5000 μm, and more preferably 10 to 1000 μm.

[0066] Note that the adhesive layer is typically formed continuously, but is not limited to such a form, and may be a layer formed in a regular or random pattern such as dots or stripes.

[0067] The adhesive layer may be formed using a solventless coating method such as rolling or extrusion. In this case, the adhesive composition can be obtained as a kneaded product by heating and kneading. For kneading, for example, batch kneaders such as kneaders, Banbury mixers, and mixing rolls, or continuous kneaders such as twin-screw kneaders are used. The heating temperature in kneading can be, for example, 80 to 180°C. The adhesive composition obtained as described above can be heated by a molding device such as an extruder, calender roll, press machine (hot press machine), etc. to form an adhesive layer in a sheet form.

[0068] 〔Adhesive Sheet〕 The adhesive sheet according to an embodiment of the present invention includes an adhesive layer according to an embodiment of the present invention. The adhesive layer according to an embodiment of the present invention is composed of the adhesive composition according to an embodiment of the present invention. Further, in the adhesive sheet according to an embodiment of the present invention, it is preferable that the adhesive layer is formed on a base material. Here, when referring to an "adhesive sheet" in this specification, those referred to as "adhesive tape", "adhesive label", "adhesive film", etc. may be included. It may be a base material-free adhesive sheet in a form in which the above adhesive layer is held by a release liner. Further, the adhesive sheet of the present embodiment may include another adhesive layer having a composition different from that of the above adhesive layer. The "adhesive surface" is the surface (attachment surface) on the side of the adhesive sheet that is attached to the adherend. In the adhesive sheet of the present invention, only one side may be the adhesive surface, or both sides may be the adhesive surfaces. Also, the "unreacted state" represents a state in which a curing reaction by water or a compound having active hydrogen does not occur. Or, it represents a state in which a functional group capable of chemically bonding to the adherend remains. In the adhesive sheet of the present invention, only one side may be the adhesive surface, or both sides may be the adhesive surfaces. Also, in this specification, "(meth)acrylic" means acrylic or methacrylic, and similarly, "(meth)acrylate" means acrylate or methacrylate.

[0069] FIG. 1 is an example of a schematic cross-sectional view of an adhesive sheet according to an embodiment of the present invention. The adhesive sheet 10 of the present embodiment includes a base material 11 and an adhesive layer 12, and the surface of the adhesive layer 12 on the side opposite to the base material 11 may be detachably covered by a release liner 13. The pressure-sensitive adhesive sheet 10 of the present embodiment is used by peeling off the release liner 13 and attaching it to an adherend through the pressure-sensitive adhesive layer 12. That is, in the pressure-sensitive adhesive layer 12 in the present embodiment, the surface on the release liner 13 side is the pressure-sensitive adhesive surface.

[0070] The pressure-sensitive adhesive sheet according to the embodiment of the present invention may include pressure-sensitive adhesive layers on both sides of a base material as shown in FIG. 2, and the pressure-sensitive adhesive layers may be protected by release liners. The pressure-sensitive adhesive sheet 30 of the present embodiment may include a first release liner 33A, a first pressure-sensitive adhesive layer 32A, a base material 31, a second pressure-sensitive adhesive layer 32B, and a second release liner 33B in this order. The pressure-sensitive adhesive sheet 30 of the present embodiment is used by peeling off the first release liner 33A and the second release liner 33B and attaching the first pressure-sensitive adhesive layer 32A and the second pressure-sensitive adhesive layer 32B to different adherends, respectively. That is, in the present embodiment, both the surface of the first pressure-sensitive adhesive layer 32A on the first release liner 33A side and the surface of the second pressure-sensitive adhesive layer 32B on the second release liner 33B side are pressure-sensitive adhesive surfaces.

[0071] The base material 31, the first and second pressure-sensitive adhesive layers 32A and 32B, and the first and second release liners 33A and 33B in the present embodiment are the same as the base material 11, the pressure-sensitive adhesive layer 12, and the release liner 13 described above.

[0072] Further, the pressure-sensitive adhesive sheet 30 in the present embodiment may be wound. That is, the pressure-sensitive adhesive sheet 30 of the present embodiment may be wound, for example, without including the second release liner 33B, such that the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer 32B is attached to the surface of the first release liner 33A opposite to the first pressure-sensitive adhesive layer 32A.

[0073] The pressure-sensitive adhesive sheet according to the embodiment of the present invention may not include a base material and may protect both sides of the pressure-sensitive adhesive layer with release liners as shown in FIG. 3. That is, the pressure-sensitive adhesive sheet 40 of the present embodiment may include a first release liner 43A, a pressure-sensitive adhesive layer 42, and a second release liner 43B in this order. The pressure-sensitive adhesive sheet 40 of the present embodiment is used by peeling off the first release liner 43A and the second release liner 43B and attaching one surface and the other surface of the pressure-sensitive adhesive layer 42 to different adherends, respectively. That is, in the present embodiment, both the surface of the pressure-sensitive adhesive layer 42 on the side of the first release liner 43A and the surface on the side of the second release liner 43B are pressure-sensitive adhesive surfaces.

[0074] The pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a pressure-sensitive adhesive sheet in which the adhesive strength of the pressure-sensitive adhesive layer decreases by irradiating active energy rays. When the pressure-sensitive adhesive sheet according to the embodiment of the present invention is used for protecting members in the manufacturing process of electronic components or electronic devices, etc., by irradiating active energy rays, the adhesive strength of the pressure-sensitive adhesive layer decreases, so that a decrease in yield due to deformation or breakage of the members during peeling can be suppressed.

[0075] Examples of the active energy rays include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays; electromagnetic waves such as X-rays and γ-rays; electron beams; proton beams; neutron beams; and the like. In the embodiment of the present invention, ultraviolet rays are preferable in terms of being able to more effectively exhibit the effects of the present invention.

[0076] When irradiating the pressure-sensitive adhesive sheet according to the embodiment of the present invention with active energy rays, the irradiation direction can adopt any appropriate irradiation direction as long as the effects of the present invention are not impaired. As such an irradiation direction, the incident angle with respect to the sheet surface of the pressure-sensitive adhesive sheet according to the embodiment of the present invention is preferably more than 0° and 90° or less, more preferably 30° to 90°, still more preferably 45° to 90°, and particularly preferably 60° to 90°.

[0077] The 180-degree peel strength of the pressure-sensitive adhesive sheet according to the embodiment of the present invention against the SUS plate after ultraviolet irradiation is preferably 0.5 N / 20 mm or less, more preferably 0.3 N / 20 mm or less, and still more preferably 0.22 N / 20 mm or less. The lower limit of the peel strength of the pressure-sensitive adhesive sheet according to the embodiment of the present invention after ultraviolet irradiation can take any appropriate lower limit as long as the effects of the present invention are not impaired. As such a lower limit of the peel strength of the pressure-sensitive adhesive sheet of the present invention after ultraviolet irradiation, for example, it is 0.01 N / 20 mm or more. If the peel strength of the pressure-sensitive adhesive sheet according to the embodiment of the present invention after ultraviolet irradiation is 0.5 N / 20 mm or less, the pressure-sensitive adhesive sheet can exhibit excellent easy-peelability by ultraviolet irradiation. When the peel strength of the pressure-sensitive adhesive sheet according to the embodiment of the present invention after ultraviolet irradiation exceeds 0.5 N / 20 mm, the pressure-sensitive adhesive sheet may be inferior in easy-peelability even when ultraviolet irradiation is performed.

[0078] The adhesive strength after ultraviolet irradiation is measured according to JIS Z0237:2009. However, after the pressure-sensitive adhesive sheet is attached to the test plate and allowed to stand for 30 minutes, ultraviolet irradiation is performed for 1 minute (high-pressure mercury lamp, 500 mJ / cm 2 ), and the peel adhesive strength (peel strength) is measured. The test plate is a SUS plate, and toluene is used as the cleaning solvent for the test plate. More specifically, it will be described later in the column of Examples.

[0079] (Base material) Examples of the material for forming the base material include polyolefin films such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester films such as polyethylene terephthalate; plastic films such as polyvinyl chloride; papers such as kraft paper and Japanese paper; cloths such as cotton cloth and spunbonded cloth; polyester nonwoven fabrics, Non-woven fabric such as vinylon non-woven fabric etc.; and metal foils. The thickness of the base material is not particularly limited.

[0080] The plastic films may be unstretched films or stretched (uniaxially stretched or biaxially stretched) films. Further, surface treatments such as application of a primer and corona discharge treatment may be performed on the surface of the base material where the adhesive layer is provided.

[0081] In this embodiment, the adhesive sheet may be perforated to provide through-holes. By doing so, when the adhesive sheet is attached to the adherend, the moisture on the wet surface of the adherend can escape through the through-holes to the back side (the side opposite to the attachment surface) of the adhesive sheet, so that more moisture on the wet surface of the adherend can be removed.

[0082] (Release liner) In the adhesive sheet of this embodiment, the adhesive layer and other adhesive layers according to the embodiment of the present invention may be protected by a release liner (separator, release film) until use.

[0083] As the release liner, conventional release paper or the like can be used and is not particularly limited. For example, a base material having a release treatment layer, a low-adhesion base material made of a fluoropolymer, a low-adhesion base material made of a nonpolar polymer, etc. can be used. Examples of the base material having a release treatment layer include a plastic film or paper surface-treated with a release treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, etc. Examples of the fluoropolymer of the low-adhesion base material made of a fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride copolymer, etc. Examples of the nonpolar polymer of the low-adhesion base material made of a nonpolar polymer include olefin resins (for example, polyethylene, polypropylene, etc.). The release liner can be formed by a known or conventional method. Also, the thickness of the release liner is not particularly limited.

[0084] (Adherend) Examples of the adherend include, for example, concrete, mortar, asphalt, metals (e.g., SUS plates, Al plates, etc.), wood, tiles, plastic materials (e.g., acrylic plates, baking plates, etc.), building exterior and interior materials such as coating surfaces and the inner walls of bathrooms, underwater and water surface structures such as ships and buoys, water tanks, bathtubs, sports equipment, etc.), fabrics such as woven fabrics and non-woven fabrics, paper, porous bodies such as electrolyte membranes, separation membranes, filters, and printed wiring boards. Further, the adherend may be a living organism, and may be the outside of a living organism (e.g., skin, outer shell, scales, etc.) or the inside of a living organism (e.g., teeth, bones, etc.).

Example

[0085] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples at all.

[0086] (Example 1) (Preparation of Adhesive Composition) To a mixture composed of 90 parts by mass of methoxyethyl acrylate (MEA) (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 5 parts by mass of N-vinyl-2-pyrrolidone (NVP) (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4HBA) (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer, 0.1 part by mass of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by BASF) and 0.1 part by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651 manufactured by BASF) were added as photoinitiators. After performing nitrogen substitution for 30 minutes under the condition of 0.3 L / min, the composition was irradiated with ultraviolet rays, and prepolymerization was carried out until the viscosity at room temperature (25 °C) reached about 20 Pa·s, and prepolymer 1 with a polymerization rate of about 8% was obtained.

[0087] Next, 0.02 parts by mass of hexanediol diacrylate (HDDA, Biscoat #230 manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a crosslinking agent and 0.1 part by mass of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by BASF) as a photopolymerization initiator were added to the prepolymer 1 and stirred. This mixed solution was applied onto a release liner of a PET film (trade name "Diafoil MRF", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) to a thickness of 100 μm to form a coating layer, and a release liner of a PET film (trade name "Diafoil MRE", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) was laminated on the surface of the coating layer as a cover release film to obtain a laminate. The laminate was irradiated with ultraviolet rays under the conditions of an illuminance of 6.5 mW / cm 2 , an integrated light quantity of 3000 mJ / cm 2 to cure the coating layer by photocuring to form an adhesive layer, and an adhesive sheet having release films on both sides was prepared. Thereafter, the cover release film was peeled off, and a 50-μm-thick PET film (Diafoil T100-50 manufactured by Mitsubishi Resin Corporation) was laminated to prepare an adhesive sheet.

[0088] (Example 2) An adhesive sheet of Example 2 was prepared in the same manner as in Example 1, except that the monomers used were changed to 85 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer.

[0089] (Example 3) An adhesive sheet of Example 3 was prepared in the same manner as in Example 1, except that the monomers used were changed to 80 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 15 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer.

[0090] (Example 4) The monomer used was changed to 70 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, and 25 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer. Otherwise, the pressure-sensitive adhesive sheet of Example 4 was prepared in the same manner as in Example 1.

[0091] (Example 5) The monomer used was changed to 50 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, and 45 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer. Otherwise, the pressure-sensitive adhesive sheet of Example 5 was prepared in the same manner as in Example 1.

[0092] (Example 6) Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 85 parts by volume of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer, 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.), a hydroxyl group-containing monomer, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 300 parts by mass of ethyl acetate were charged. While gently stirring, nitrogen gas was introduced, and the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 60°C to prepare Acrylic Polymer Ethyl Acetate Solution 1 (solid content concentration: 25%). Next, 0.5 part by mass of a trimethylolpropane adduct of tolylene diisocyanate (Coronate L manufactured by Tosoh Corporation), as a crosslinking agent, was added to 1 part by mass of an ethyl acetate solution of an acrylic polymer and stirred. This mixed solution was applied onto a PET film release liner (trade name "Diafoil MRF", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm), and heat-dried at 130°C for 10 minutes to create a coating layer with a thickness of 100 μm. Thereafter, a PET film release liner (trade name "Diafoil MRE", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) was laminated onto the surface of the coating layer as a cover release film, and heat-treated at 50°C for 48 hours to form an adhesive layer, thereby creating the pressure-sensitive adhesive sheet of Example 6.

[0093] (Example 7) A pressure-sensitive adhesive sheet of Example 7 was created in the same manner as in Example 1, except that the monomers used were changed to 90 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 5 parts by mass of acryloylmorpholine (ACMO manufactured by KJ Chemicals Co., Ltd.) as a water-soluble hydrophilic monomer.

[0094] (Example 8) A pressure-sensitive adhesive sheet of Example 8 was created in the same manner as in Example 1, except that the monomers used were changed to 70 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 25 parts by mass of acryloylmorpholine (ACMO manufactured by KJ Chemicals Co., Ltd.) as a water-soluble hydrophilic monomer.

[0095] (Example 9) A pressure-sensitive adhesive sheet of Example 9 was created in the same manner as in Example 1, except that the monomers used were changed to 90 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 5 parts by mass of hydroxyethyl acrylamide (HEAA manufactured by KJ Chemicals Co., Ltd.) as a water-soluble hydrophilic monomer.

[0096] (Example 10) The pressure-sensitive adhesive sheet of Example 10 was prepared in the same manner as in Example 1, except that the monomers used were changed to 70 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, and 25 parts by mass of hydroxyethylacrylamide (HEAA manufactured by KJ Chemicals Co., Ltd.), a water-soluble hydrophilic monomer.

[0097] (Example 11) The pressure-sensitive adhesive sheet of Example 11 was prepared in the same manner as in Example 1, except that the monomers used were changed to 85 parts by mass of ethoxy-diethylene glycol acrylate (Light Acrylate EC-A manufactured by Kyoeisha Chemical Co., Ltd.), a water-insoluble hydrophilic monomer, and 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer.

[0098] (Example 12) The pressure-sensitive adhesive sheet of Example 12 was prepared in the same manner as in Example 1, except that the monomers used were changed to 85 parts by mass of methoxy-dipropylene glycol acrylate (Light Acrylate DPM-A manufactured by Kyoeisha Chemical Co., Ltd.), a water-insoluble hydrophilic monomer, and 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer.

[0099] (Example 13) The pressure-sensitive adhesive sheet of Example 13 was prepared in the same manner as in Example 1, except that the monomers used were changed to 85 parts by mass of methoxy-triethylene glycol acrylate (Light Acrylate MTG-A manufactured by Kyoeisha Chemical Co., Ltd.), a water-insoluble hydrophilic monomer, and 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer.

[0100] (Example 14) The monomer used was changed to 85 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, and 10 parts by mass of N-vinylformamide (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer. An adhesive sheet of Example 14 was prepared in the same manner as in Example 1 except for this change.

[0101] (Example 15) The monomer used was changed to 85 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, and 10 parts by mass of N-vinylacetamide (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer. An adhesive sheet of Example 15 was prepared in the same manner as in Example 1 except for this change.

[0102] (Example 16) The monomer used was changed to 21.25 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation), a water-insoluble hydrophobic monomer, 63.75 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.), a hydroxyl group-containing monomer. An adhesive sheet of Example 16 was prepared in the same manner as in Example 1 except for this change.

[0103] (Example 17) The monomer used was changed to 42.5 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation), a water-insoluble hydrophobic monomer, 42.5 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.), a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.), a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.), a hydroxyl group-containing monomer. An adhesive sheet of Example 17 was prepared in the same manner as in Example 1 except for this change.

[0104] (Comparative Example 1) A pressure-sensitive adhesive sheet of Comparative Example 1 was prepared in the same manner as in Example 1, except that the monomers used were changed to 95 parts by mass of methoxyethyl acrylate (Acryx C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer.

[0105] (Comparative Example 2) A pressure-sensitive adhesive sheet of Comparative Example 2 was prepared in the same manner as in Example 1, except that the monomers used were changed to 95 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer.

[0106] (Comparative Example 3) A pressure-sensitive adhesive sheet of Comparative Example 3 was prepared in the same manner as in Example 1, except that the monomers used were changed to 85 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer.

[0107] (Comparative Example 4) A pressure-sensitive adhesive sheet of Comparative Example 4 was prepared in the same manner as in Example 1, except that the monomers used were changed to 65 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 30 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer.

[0108] (Comparative Example 5) The monomer used was changed to 90 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 5 parts by mass of Acrylic Acid (AA) (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. Otherwise, the pressure-sensitive adhesive sheet of Comparative Example 5 was prepared in the same manner as in Example 1.

[0109] (Comparative Example 6) The monomer used was changed to 60 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 35 parts by mass of acrylic acid (Acrylic Acid (AA) manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. Otherwise, the pressure-sensitive adhesive sheet of Comparative Example 6 was prepared in the same manner as in Example 1.

[0110] (Comparative Example 7) The monomer used was changed to 63.75 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 21.25 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. Otherwise, the pressure-sensitive adhesive sheet of Comparative Example 7 was prepared in the same manner as in Example 1.

[0111] (Example 18) The monomer used was changed to 10 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 75 parts by mass of methoxyethyl acrylate (Aclic C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. An adhesive sheet of Example 18 was prepared in the same manner as in Example 1 except for the above changes.

[0112] (Example 19) The monomer used was changed to 25 parts by mass of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 60 parts by mass of methoxyethyl acrylate (Aclic C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. An adhesive sheet of Example 19 was prepared in the same manner as in Example 1 except for the above changes.

[0113] (Example 20) The monomer used was changed to 10 parts by mass of normal butyl acrylate (BA) as a water-insoluble hydrophobic monomer, 75 parts by mass of methoxyethyl acrylate (Aclic C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. An adhesive sheet of Example 20 was prepared in the same manner as in Example 1 except for the above changes.

[0114] (Example 21) The monomer used was changed to 25 parts by mass of normal butyl acrylate (BA) as a water-insoluble hydrophobic monomer, 60 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. A pressure-sensitive adhesive sheet of Example 21 was prepared in the same manner as in Example 1 except for the above changes.

[0115] (Example 22) The monomer used was changed to 10 parts by mass of isononyl acrylate (INAA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a water-insoluble hydrophobic monomer, 75 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. A pressure-sensitive adhesive sheet of Example 22 was prepared in the same manner as in Example 1 except for the above changes.

[0116] (Example 23) The monomer used was changed to 25 parts by mass of isononyl acrylate (INAA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a water-insoluble hydrophobic monomer, 60 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. A pressure-sensitive adhesive sheet of Example 23 was prepared in the same manner as in Example 1 except for the above changes.

[0117] (Comparative Example 8) The monomer used was changed to 50 parts by mass of isononyl acrylate (INAA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a water-insoluble hydrophobic monomer, 35 parts by mass of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 10 parts by mass of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, and 5 parts by mass of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer. A pressure-sensitive adhesive sheet of Comparative Example 8 was prepared in the same manner as in Example 1 except for the above changes.

[0118] <Measurement of water absorption> Method for measuring water absorption: The pressure-sensitive adhesive layer obtained above with a thickness of 100 μm was attached to a PET film subjected to corona treatment with a thickness of 50 μm, cut into 2.5 cm × 5 cm, and the measurement sample obtained by peeling off the separator was immersed in pure water under the following conditions, and then the mass after removing the adhering moisture with a blower and the mass before immersion were calculated from the difference. Immersion temperature: 23°C Immersion time: 5 minutes

[0119] <Measurement of 180-degree peel strength from a slate board> The 180-degree peel strength from a slate board was measured in the following manner. The results are shown in Tables 1 to 3. First, the pressure-sensitive adhesive sheets of each example were cut to a width of 20 mm and a length of 10 cm.

[0120] Next, a slate standard board manufactured by Nippon Test Panel Co., Ltd., product name "JIS A5430 (FB)" (hereinafter also referred to as a slate board), with a size of 3 mm in thickness, 30 mm in width, and 125 mm in length was prepared. The glossy surface of this slate board was used.

[0121] Subsequently, the prepared slate board was immersed in water and degassed for 1 hour with an ultrasonic degassing device (BRANSON 3510 manufactured by Yamato Scientific Co., Ltd.), allowed to stand overnight, and then taken out of the water.

[0122] Subsequently, the water on the slate board was wiped off, and each example of the adhesive sheet (test piece) created on the glossy surface was pressed and pasted with a 2 kg roller in one round trip, wrapped with wrap and aluminum foil, and left standing at 23°C for the times (1 minute, 5 minutes, 30 minutes) described in Tables 1 to 3. Then, using a tensile testing machine (Autograph AGS-50NX manufactured by Shimadzu Corporation), the 180-degree peel strength (N / 20 mm) against the slate board at a peel temperature of 23°C and a peel rate of 300 mm / min was measured.

[0123] <Measurement of 180-degree peel strength against mortar board> Except for changing the slate board to a mortar board, in the same manner as the measurement of the 180-degree peel strength against the slate board described above, the mortar board with the adhesive sheet (test piece) attached was wrapped with wrap and aluminum foil, left standing, and the 180-degree peel strength (N / 20 mm) was measured after 1 minute and 5 minutes.

[0124] <Corrosion test against aluminum plate> After each adhesive sheet was bonded to an aluminum foil with a thickness of 20 μm, it was stored in a high-temperature and high-humidity environment of 85°C and 85% humidity for 72 hours, and then the discoloration (degree of corrosion) of the bonding surface of the adhesive sheet was visually judged. 〇: No discoloration of aluminum foil △: Some discoloration of aluminum foil ×: Discoloration over the entire pasted area

[0125] <Measurement of water contact angle> A 10 μL droplet was dropped onto the adhesive surface of each adhesive sheet, and after 5 minutes had elapsed, the water contact angle on the surface of the adhesive layer was measured using a contact angle meter (Dropmaster manufactured by Kyowa Interface Science Co., Ltd.) by the sessile drop method according to JIS R3257.

[0126] The materials used in each example and comparative example and the evaluation results are shown in Tables 1 to 3.

[0127]

Table 1

[0128]

Table 2

[0129]

Table 3

[0130] The structures of the monomers and crosslinking agents used in the examples and comparative examples are shown in Tables 4 to 6.

[0131]

Table 4

[0132]

Table 5

[0133]

Table 6

[0134] In the pressure-sensitive adhesive sheets of Examples 1 to 23, adhesion was immediately exhibited to the adherend in a wet state. On the other hand, Comparative Examples 1 to 4 and Comparative Example 7 with a small water absorption amount of the pressure-sensitive adhesive showed no adhesiveness regardless of the sticking time. Further, Comparative Examples 5 to 6 showed adhesiveness to the adherend in a wet state, but corrosion to the metal occurred due to the inclusion of an acidic component.

[0135] (Example 24) Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 70.8 parts by mass (100 mol%) of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 0.6 parts by mass (1 mol%) of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, 15.7 parts by mass (20 mol%) of 4-hydroxybutyl acrylate (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 300 parts by mass of ethyl acetate were charged. While gently stirring, nitrogen gas was introduced, and the polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 60°C to prepare an ethyl acetate solution 2 (solid content concentration 25%) of an acrylic polymer.

[0136] Thereafter, 13.5 parts by mass (16 mol%) of methacryloyloxyethyl isocyanate (MOI) was added, and the liquid temperature in the flask was maintained at around 50°C to carry out an addition reaction. Next, 1.0 part by mass of a trimethylolpropane adduct of tolylene diisocyanate (Coronate L manufactured by Tosoh Corporation) as a crosslinking agent and 1 part by mass of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by BASF) as a photopolymerization initiator were added to the ethyl acetate solution 2 of the acrylic polymer after the above addition reaction and stirred. This mixed solution was applied onto a release liner of a PET film (trade name "Diafoil MRF", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) and dried by heating at 130°C for 10 minutes to create an adhesive layer with a thickness of 100 μm. Thereafter, a release liner of a PET film (trade name "Diafoil MRE", manufactured by Mitsubishi Chemical Corporation, thickness 38 μm) was laminated on the surface of the coated layer as a cover release film, and heat treatment was carried out at 50°C for 48 hours to create the adhesive sheet of Example 24.

[0137] (Example 25) The monomers used were changed to 67.6 parts by mass (95 mol%) of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 3.0 parts by mass (5 mol%) of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, 15.8 parts by mass (20 mol%) of 4-hydroxybutyl acrylate (4HBA) (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer, and 10.8 parts by mass (16 mol%) of methacryloyloxyethyl isocyanate (MOI). A pressure-sensitive adhesive sheet of Example 25 was prepared in the same manner as in Example 24 except for the above changes.

[0138] (Example 26) The monomers used were changed to 57.8 parts by mass (80 mol%) of methoxyethyl acrylate (Acrilex C-1 manufactured by Toagosei Co., Ltd.) as a water-insoluble hydrophilic monomer, 12.4 parts by mass (20 mol%) of N-vinyl-2-pyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble hydrophilic monomer, 16.0 parts by mass (20 mol%) of 4-hydroxybutyl acrylate (4HBA) (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer, and 13.8 parts by mass (16 mol%) of methacryloyloxyethyl isocyanate (MOI). A pressure-sensitive adhesive sheet of Example 26 was prepared in the same manner as in Example 24 except for the above changes.

[0139] (Comparative Example 9) The monomers used were changed to 77.4 parts by mass (100 mol%) of 2-ethylhexyl acrylate (2EHA manufactured by Mitsubishi Chemical Corporation) as a water-insoluble hydrophobic monomer, 12.1 parts by mass (20 mol%) of 4-hydroxybutyl acrylate (4HBA) (4-HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a hydroxyl group-containing monomer, and 10.4 parts by mass (16 mol%) of methacryloyloxyethyl isocyanate (MOI). A pressure-sensitive adhesive sheet of Comparative Example 9 was prepared in the same manner as in Example 24 except for the above changes.

[0140] For the pressure-sensitive adhesive sheets of Examples 24 to 26 and Comparative Example 9, the 180-degree peel strength with respect to the SUS plate was measured in the following manner. The results are shown in Table 7.

[0141] First, the adhesive sheets of each example were cut into a width of 20 mm and a length of 10 cm. Next, SUS304BA was used as the adherend, and a SUS plate with a thickness of 1 mm, a width of 30 mm, and a length of 125 mm was prepared. The surface of this adherend that had been thoroughly cleaned with toluene and degreased was used.

[0142] <Measurement of peel strength (Dry surface) before UV irradiation> Each example's adhesive sheet (test piece) prepared on the glossy surface of the dried SUS plate was pressed and adhered with a 2 kg roller in one round trip, and left standing for 30 minutes. Subsequently, using a tensile testing machine (Autograph AGS-50NX manufactured by Shimadzu Corporation), the 180-degree peel strength (N / 20 mm) of each example's adhesive sheet with respect to the SUS plate at a peel temperature of 23°C and a peel rate of 300 mm / min was measured.

[0143] <Measurement of peel strength (Dry surface) after UV irradiation> Each example's adhesive sheet (test piece) prepared on the glossy surface of the dried SUS plate was pressed and adhered with a 2 kg roller in one round trip, and left standing for 30 minutes. Subsequently, ultraviolet irradiation (high-pressure mercury lamp, 500 mJ / cm 2 ) was performed for 1 minute. Subsequently, using a tensile testing machine (Autograph AGS-50NX manufactured by Shimadzu Corporation), the 180-degree peel strength (N / 20 mm) of each example's adhesive sheet with respect to the SUS plate at a peel temperature of 23°C and a peel rate of 300 mm / min was measured.

[0144] <Measurement of peel strength (Wet adhesion) before UV irradiation> The degreased SUS plate was immersed in water and then taken out.

[0145] Subsequently, with moisture remaining on the surface of the SUS plate, each example's adhesive sheet (test piece) prepared on the glossy surface was pressed and adhered with a 2 kg roller in one round trip, and left standing for 30 minutes.

[0146] Subsequently, using a tensile testing machine (Autograph AGS-50NX manufactured by Shimadzu Corporation), the 180-degree peel strength (N / 20 mm) of the adhesive sheet of each example against the SUS plate at a peel temperature of 23°C and a peel rate of 300 mm / min was measured.

[0147] <Measurement of Peel Strength after UV Irradiation (Wet Attachment)> The degreased SUS plate was immersed in water and then taken out of the water.

[0148] Subsequently, with moisture remaining on the surface of the SUS plate, the adhesive sheet (test piece) of each example prepared on the glossy surface was pressed and attached with a 2 kg roller in one round trip and left standing for 30 minutes.

[0149] Subsequently, ultraviolet irradiation (high-pressure mercury lamp, 500 mJ / cm 2 ) was performed for 1 minute. Subsequently, using a tensile testing machine (Autograph AGS-50NX manufactured by Shimadzu Corporation), the 180-degree peel strength (N / 20 mm) of the adhesive sheet of each example against the SUS plate at a peel temperature of 23°C and a peel rate of 300 mm / min was measured.

[0150]

Table 7

[0151] In Table 7, "phr" represents the compounding amount (parts by mass) of the additive with respect to 100 parts by mass of the polymer.

Explanation of Symbols

[0152] 10, 30, 40 Adhesive Sheet 11, 31 Substrate 12, 42 Adhesive Layer 13 Release Liner 32A First Adhesive Layer 32B Second Adhesive Layer 33A, 43A First Release Liner 33B, 43B Second Release Liner

Claims

1. An adhesive composition containing a base polymer, wherein the base polymer is a copolymer containing a structure derived from (a) at least one monomer selected from methoxyethyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-dipropylene glycol acrylate, and methoxy-triethylene glycol acrylate, and (b) at least one monomer selected from N-vinyl-2-pyrrolidone, hydroxyethyl acrylamide, vinyl formamide, and N-vinyl acetamide, and the content ratio of the structure derived from the monomer of (a) in the base polymer is 40% by mass or more. An adhesive composition.

2. The adhesive composition according to Claim 1, wherein the adhesive layer formed from the adhesive composition has a water absorption of 9.0 mg or more as measured by the following method. An adhesive composition. Method for measuring water absorption: The adhesive layer with a thickness of 100 μm is attached to a PET film with a thickness of 50 μm, and the measurement sample obtained by cutting it into 2.5 cm × 5 cm is calculated from the difference between the mass after immersion in pure water under the following conditions and the mass before immersion. Immersion temperature: 23°C Immersion time: 5 minutes

3. The adhesive composition according to Claim 1 or 2, further containing a crosslinking agent, wherein the crosslinking agent is at least one selected from a photocuring agent or an isocyanate compound.

4. The adhesive composition according to Claim 3, wherein the photocuring agent is a photocurable monomer or a photocurable oligomer.

5. An adhesive layer comprising the adhesive composition according to any one of Claims 1 to 4.

6. The swelling degree after immersion in water at 5°C for 24 hours is 2.5 to 10, The adhesive layer according to Claim 5, wherein the swelling degree after immersion in water at 23°C for 24 hours is 1.0 to 2.

5.

7. An adhesive sheet comprising the adhesive layer according to Claim 5 or 6.

8. The adhesive sheet according to Claim 7, wherein the adhesive layer is formed on a substrate.

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