JP2022046284A - Color-changeable adhesive sheet - Google Patents

Abstract

To provide a color-changeable adhesive sheet that can change the color of at least part of an adhesive layer after bonded to an adherend, and is suitable for suppressing the degradation of the color-change portion of the adhesive layer.SOLUTION: An adhesive sheet S (color-changeable adhesive sheet) according to the present invention comprises an adhesive layer 10. The adhesive layer 10 either includes a base polymer and a monomer ingredient, or includes as a base polymer a polymerization product of a monomer ingredient. In the adhesive sheet S, the monomer ingredient contains an acid-generating agent having a polymerizable functional group, and the adhesive layer 10 contains a chromogenic compound producing a color by reaction with an acid. Alternatively, the monomer ingredient contains a chromogenic compound having a polymerizable functional group and producing a color by reaction with an acid, and the adhesive layer 10 contains an acid-generating agent. Alternatively, the monomer ingredient contains an acid-generating agent having a polymerizable functional group, and a chromogenic compound having a polymerizable functional group and producing a color by reaction with an acid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a variable color adhesive sheet.

A display panel such as an organic EL panel has a laminated structure including a pixel panel, a cover member, and the like. In the process of manufacturing such a display panel, for example, a transparent adhesive sheet is used for bonding the elements included in the laminated structure.

Further, as a transparent adhesive sheet arranged on the light emitting side (image display side) of the pixel panel in the display panel, a colored portion for imparting design, shielding, antireflection, etc. to a predetermined portion of the sheet is previously provided. It has been proposed to use the formed pressure-sensitive adhesive sheet. Such an adhesive sheet is described in, for example, Patent Document 1 below. Patent Document 1 specifically describes an adhesive sheet having a colored portion containing a carbon black pigment.

Japanese Unexamined Patent Publication No. 2017-203810

However, in the process of manufacturing a display panel, when an adhesive sheet having a colored portion formed in advance is used, a foreign substance between the adherend and the colored portion of the adhesive sheet is used after the adhesive sheet is attached to the adherend. And the presence or absence of air bubbles cannot be properly inspected. In the bonding of adhesive sheets in the process of manufacturing a display panel, it is required to be able to appropriately inspect the presence or absence of foreign matter and air bubbles between the adherend and the adhesive sheet after the bonding.

On the other hand, from the viewpoint of ensuring the function of the colored portion provided on the transparent adhesive sheet for the display panel, it is required to suppress the deterioration of the colored portion.

The present invention provides a variable color pressure-sensitive adhesive sheet capable of discoloring at least a part of the pressure-sensitive adhesive layer after being attached to an adherend and suitable for suppressing deterioration of the discolored portion of the pressure-sensitive adhesive layer. ..

The present invention [1] comprises a pressure-sensitive adhesive layer containing a base polymer and a monomer component, or a polymer of the monomer component as a base polymer, and the monomer component is an acid generator having a polymerizable functional group. The pressure-sensitive adhesive layer further contains a chromogenic compound that develops color by reaction with an acid, or the monomer component contains a chromogenic compound that has a polymerizable functional group and develops color by reaction with an acid. , The pressure-sensitive adhesive layer further contains an acid generator, or the monomer component is a color-developing compound having a polymerizable functional group and having a polymerizable functional group and developing a color by reaction with the acid. Includes variable color adhesive sheets, including.

In the present invention [2], the content of the monomer component in the pressure-sensitive adhesive layer containing the base polymer and the monomer component is 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base polymer. The variable color adhesive sheet according to the above [1] is included.

In the present invention [3], the pressure-sensitive adhesive layer containing the base polymer and the monomer component further contains a photopolymerization initiator, the acid generator is a photoacid generator, and the photoacid generator. The variable color pressure-sensitive adhesive sheet according to the above [1] or [2], which has a wavelength region in which the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the above is 2 or more within a wavelength range of 300 nm or more and 500 nm or less. include.

The present invention [4] includes the variable color pressure-sensitive adhesive sheet according to any one of the above [1] to [3], wherein the pressure-sensitive adhesive layer has a thickness of 10 μm or more and 300 μm or less.

The present invention [5] includes the variable color pressure-sensitive adhesive sheet according to any one of the above [1] to [4], further comprising a base material arranged on one side in the thickness direction of the pressure-sensitive adhesive layer.

In the variable color pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer contains a color-developing compound that develops color by reaction with an acid and an acid generator in the above-mentioned predetermined embodiment. Therefore, after the variable color pressure-sensitive adhesive sheet is attached to the adherend, acid is generated from the acid generator in the part to be discolored (at least a part of the pressure-sensitive adhesive layer) of the pressure-sensitive adhesive layer by applying an external stimulus to the part. , The color-developing compound can be colored by the acid. According to such a variable color pressure-sensitive adhesive sheet, it is possible to inspect the presence or absence of foreign matter and air bubbles between the sheet and the adherend after bonding and before forming a discolored portion of the pressure-sensitive adhesive layer.

Further, in the pressure-sensitive adhesive layer of the variable-color pressure-sensitive adhesive sheet, as described above, at least one of the color-developing compound and the acid generator that develop color by reaction with the acid is incorporated in the base polymer or as a monomer component. It is contained in a copolymerizable state (in the latter state, at least one of the color-developing compound and the acid generator is incorporated into the polymer network by undergoing a polymerization reaction of the monomer component in the pressure-sensitive adhesive layer. Can be done). In such a variable color pressure-sensitive adhesive sheet, the color-developing compound is diffused after the discolored portion is formed in the pressure-sensitive adhesive layer (that is, after the color-developing compound is colored by the reaction with the acid derived from the acid generator). Suitable for suppressing. By suppressing the diffusion of the color-developing compound, deterioration of the discolored portion (bleeding, fading, non-uniformity of color, etc.) is suppressed.

It is sectional drawing of one Embodiment of the variable color adhesive sheet of this invention. It is sectional drawing of the modification of the variable color pressure-sensitive adhesive sheet of this invention (when the variable color pressure-sensitive adhesive sheet is a single-sided pressure-sensitive adhesive sheet with a base material). An example of how to use the variable color adhesive sheet of the present invention is shown. FIG. 3A shows a step of preparing a variable color adhesive sheet and a member (adhesive body), and FIG. 3B shows a step of joining the members to each other via the variable color adhesive sheet. FIG. 3C shows a step of curing the pressure-sensitive adhesive layer of the variable-color pressure-sensitive adhesive sheet as needed, and FIG. 3D shows a step of forming a discolored portion on the pressure-sensitive adhesive layer of the variable-color pressure-sensitive adhesive sheet.

As shown in FIG. 1, the pressure-sensitive adhesive sheet S as an embodiment of the variable-color pressure-sensitive adhesive sheet of the present invention includes the pressure-sensitive adhesive layer 10. The adhesive sheet S has a sheet shape having a predetermined thickness and extends in a direction (plane direction) orthogonal to the thickness direction. The adhesive sheet S is used, for example, as a transparent adhesive sheet arranged on the image display side of the pixel panel in a display panel such as an organic EL panel (having a laminated structure including a pixel panel and a cover member).

The pressure-sensitive adhesive layer 10 is a pressure-sensitive adhesive layer having transparency (visible light transmission) formed from the pressure-sensitive adhesive composition. The adhesive composition is any one of the following first to sixth adhesive compositions.

The first adhesive composition contains a base polymer, a monomer component (polymerizable compound), and a color-developing compound that develops color by reaction with an acid, and the monomer component contains an acid generator having a polymerizable functional group. include.

The second tacky composition contains a base polymer, a monomer component, and an acid generator, and the monomer component contains a color-developing compound having a polymerizable functional group and developing a color by reaction with an acid.

The third adhesive composition contains a base polymer and a monomer component (polymerizable compound), and the monomer component comprises an acid generator having a polymerizable functional group and an acid having a polymerizable functional group. Includes a color-developing compound that develops color by reaction.

The fourth tacky composition contains a base polymer and a color-developing compound that develops color by reaction with an acid, and the monomer component forming the base polymer contains an acid generator having a polymerizable functional group.

The fifth adhesive composition contains a base polymer and an acid generator, and the monomer component forming the base polymer contains a color-developing compound having a polymerizable functional group and developing a color by reaction with an acid.

The sixth adhesive composition contains a base polymer, and the monomer component forming the base polymer develops a color by reacting with an acid generator having a polymerizable functional group and having a polymerizable functional group. Includes sex compounds.

The base polymer in the first adhesive composition exhibits rubber elasticity at room temperature. Examples of the base polymer include acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers. From the viewpoint of ensuring good transparency and tackiness in the pressure-sensitive adhesive layer 10, an acrylic polymer is preferably used as the base polymer.

The content ratio of the base polymer in the pressure-sensitive adhesive layer 10 is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass, from the viewpoint of appropriately expressing the function of the base polymer in the pressure-sensitive adhesive layer 10. % Or more.

The acrylic polymer is, for example, a polymer obtained by polymerizing a monomer component (first monomer component) containing a (meth) acrylic acid ester in a proportion of 50% by mass or more. "(Meta) acrylic acid" means acrylic acid and / or methacrylic acid.

Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester.

Examples of the (meth) acrylic acid alkyl ester include a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms. Examples of such (meth) acrylic acid alkyl esters include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and (meth) acrylic acid. Isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, (meth) ) Hexyl acrylate, (meth) heptyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) octyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, ( Meta) decyl acrylate, (meth) isodecyl acrylate, (meth) undecyl acrylate, (meth) dodecyl acrylate, (meth) isotridecyl acrylate, (meth) tetradecyl acrylate, (meth) isotetradecyl acrylate, Pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isooctadecyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate. Can be mentioned. As the (meth) acrylic acid alkyl ester, an acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms is preferably used, and more preferably, it has methyl acrylate and an alkyl group having 2 to 12 carbon atoms. Acrylic acid alkyl ester is used in combination, and more preferably, methyl acrylate and 2-ethylhexyl acrylate are used in combination.

Examples of the (meth) acrylic acid alkoxyalkyl ester include a (meth) acrylic acid alkoxyalkyl ester having an alkoxy group having 1 to 4 carbon atoms and an alkylene group having 1 to 4 carbon atoms. Examples of such (meth) acrylic acid alkoxyalkyl esters include (meth) acrylic acid 2-methoxymethyl, (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid 2-ethoxymethyl, and (meth) acrylic. Examples thereof include 2-ethoxyethyl acid, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate. As the (meth) acrylic acid alkoxyalkyl ester, preferably, (meth) acrylic acid 2-ethoxymethyl is used, and more preferably acrylic acid 2-ethoxymethyl is used.

The (meth) acrylic acid ester may be used alone or in combination of two or more.

The ratio of the (meth) acrylic acid ester in the first monomer component is preferably 50% by mass or more, more preferably 60% by mass or more, and further, from the viewpoint of appropriately expressing basic properties such as adhesiveness in the pressure-sensitive adhesive layer 10. It is preferably 70% by mass or more. The same ratio is, for example, 99% by mass or less.

The first monomer component may contain a copolymerizable monomer copolymerizable with the (meth) acrylic acid ester. Examples of the copolymerizable monomer include a monomer having a polar group. Examples of the polar group-containing monomer include a hydroxyl group-containing monomer, a monomer having a nitrogen atom-containing ring, and a carboxy group-containing monomer. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing a cross-linking point into the acrylic polymer and ensuring the cohesive force of the acrylic polymer.

The copolymerizable monomer preferably contains at least one selected from the group consisting of a hydroxyl group-containing monomer, a monomer having a nitrogen atom-containing ring, and a carboxy group-containing monomer. More preferably, the copolymerizable monomer comprises a hydroxyl group-containing monomer and / or a monomer having a nitrogen atom-containing ring.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth). ) 4-Hydroxybutyl acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and ( Examples thereof include 4-hydroxymethylcyclohexyl) methyl (meth) acrylate. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, and more preferably 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. ..

The ratio of the hydroxyl group-containing monomer in the first monomer component is preferably 1% by mass or more, more preferably 3% by mass, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring the cohesive force in the pressure-sensitive adhesive layer 10. Above, more preferably 5% by mass or more. The same ratio is preferable from the viewpoint of adjusting the viscosity of the polymerization reaction solution during the polymerization of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the pressure-sensitive adhesive layer 10 and the acrylic polymer). Is 30% by mass or less, more preferably 20% by mass or less.

Examples of the monomer having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, and N-vinylpyrazine. N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl. -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N -Vinylthiazole and N-vinylisothiazole are mentioned. As the monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

The proportion of the monomer having a nitrogen atom-containing ring in the first monomer component is preferably 1 from the viewpoint of ensuring the cohesive force in the pressure-sensitive adhesive layer 10 and the adhesion to the adherend in the pressure-sensitive adhesive layer 10. By mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more. The same ratio is preferably 30 mass from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the pressure-sensitive adhesive layer 10 and the acrylic polymer). % Or less, more preferably 20% by mass or less.

Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The ratio of the carboxy group-containing monomer in the first monomer component is determined from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring the cohesive force in the pressure-sensitive adhesive layer 10, and ensuring the adhesion to the adherend in the pressure-sensitive adhesive layer 10. Is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more. The same ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid.

The first monomer component may contain other copolymerizable monomers. Examples of other copolymerizable monomers include acid anhydride monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, amide group-containing monomers, monomers having a succinimide skeleton, and maleimides. Classes, itaconimides, vinyl esters, vinyl ethers, and aromatic vinyl compounds.

Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, and sulfopropyl (meth). Examples include acrylates and (meth) acryloyloxynaphthalene sulfonic acid.

Examples of the phosphoric acid group-containing monomer include 2-hydroxyethylacryloyl phosphate.

Examples of the epoxy group-containing monomer include epoxy group-containing acrylates such as glycidyl (meth) acrylate and -2-ethyl glycidyl ether (meth) acrylate, allyl glycidyl ether, and glycidyl ether (meth) acrylate.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the amide group-containing monomer include N-vinylcarboxylic acid amides such as (meth) acrylamide, N, N-dialkyl (meth) acrylamide, N-alkyl (meth) acrylamide, and N-vinylacetamide, and N-hydroxyalkyl. Examples include (meth) acrylamide, N-alkoxyalkyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, and N- (meth) acryloylmorpholin. Examples of N, N-dialkyl (meth) acrylamide include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, and N, N-diisopropyl ( Examples include meth) acrylamide, N, N-di (n-butyl) (meth) acrylamide, and N, N-di (t-butyl) (meth) acrylamide. Examples of N-alkyl (meth) acrylamide include N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and Nn-butyl (meth) acrylamide. Examples of N-hydroxyalkyl (meth) acrylamide include N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, and N- (1-hydroxypropyl) (meth). Acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, and N- (4-hydroxybutyl) Examples include (meth) acrylamide. Examples of N-alkoxyalkyl (meth) acrylamide include N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

Examples of the monomer having a succinimide skeleton include N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyhexamethylene succinimide. Be done.

Examples of maleimides include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide.

Examples of the itaconimides include N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide can be mentioned.

Examples of vinyl esters include vinyl acetate and vinyl propionate.

Examples of vinyl ethers include methyl vinyl ether and ethyl vinyl ether.

Aromatic vinyl compounds include, for example, styrene, α-methylstyrene, and vinyltoluene. Examples of olefins include ethylene, butadiene, isoprene, and isobutylene.

The copolymerizable monomer may be used alone or in combination of two or more.

The acrylic polymer can be formed by polymerizing the above-mentioned first monomer component. Examples of the polymerization method include solution polymerization, bulk polymerization, and emulsion polymerization, and solution polymerization is preferable. In solution polymerization, for example, a first monomer component and a polymerization initiator are mixed with a solvent to prepare a reaction solution, and then the reaction solution is heated. Then, an acrylic polymer solution containing an acrylic polymer can be obtained by undergoing a polymerization reaction of the first monomer component in the reaction solution. As the polymerization initiator, for example, a thermal polymerization initiator is used. The amount of the polymerization initiator used is, for example, 0.05 parts by mass or more and, for example, 1 part by mass or less with respect to 100 parts by mass of the first monomer component.

Examples of the thermal polymerization initiator include an azo polymerization initiator and a peroxide polymerization initiator. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 2,2'-azobis (2-methylpropionic acid) dimethyl. 4,4'-Azobis-4-cyanovaleric acid, azobisisobutyvaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2-) Imidazoline-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, and 2,2'-azobis (N, N'-dimethyleneisobutyramidin) dihydrochloride Can be mentioned. Examples of the peroxide polymerization initiator include dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxide.

The weight average molecular weight of the acrylic polymer is preferably 100,000 or more, more preferably 300,000 or more, still more preferably 500,000 or more, from the viewpoint of ensuring the cohesive force in the pressure-sensitive adhesive layer 10. The weight average molecular weight is preferably 5,000,000 or less, more preferably 3,000,000 or less, still more preferably 2000000 or less. The weight average molecular weight of the acrylic polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

The glass transition temperature (Tg) of the base polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower, still more preferably −20 ° C. or lower. The glass transition temperature is, for example, −80 ° C. or higher.

As the glass transition temperature (Tg) of the polymer, the glass transition temperature (theoretical value) obtained based on the following Fox formula can be used. The Fox formula is a relational expression between the glass transition temperature Tg of the polymer and the glass transition temperature Tgi of the homopolymer of the monomer constituting the polymer. In the Fox formula below, Tg represents the glass transition temperature (° C.) of the polymer, Wi represents the weight fraction of the monomer i constituting the polymer, and Tgi represents the glass transition of the homopolymer formed from the monomer i. Indicates the temperature (° C). Literature values can be used for the glass transition temperature of homopolymers, for example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Bunko 7 Introduction to Synthetic Resins for Paints". (Kyozo Kitaoka, Polymer Publications, 1995) lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of the homopolymer of the monomer can also be obtained by the method specifically described in JP-A-2007-51271.

Fox formula 1 / (273 + Tg) = Σ [Wi / (273 + Tgi)]

The first tacky composition may contain a cross-linking agent from the viewpoint of introducing a cross-linked structure into the base polymer. Examples of the cross-linking agent include an isocyanate cross-linking agent, an epoxy cross-linking agent, an oxazoline cross-linking agent, an aziridine cross-linking agent, a carbodiimide cross-linking agent, and a metal chelate cross-linking agent. The cross-linking agent may be used alone or in combination of two or more.

Examples of the isocyanate cross-linking agent include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalin diisocyanate, and triphenylmethane tri. Examples thereof include isocyanates and polymethylene polyphenyl isocyanates. Further, examples of the isocyanate cross-linking agent include derivatives of these isocyanates. Examples of the isocyanate derivative include isocyanurate-modified products and polyol-modified products. Examples of commercially available isocyanate cross-linking agents include coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), and coronate HX (hexa). Examples thereof include isocyanurate form of methylene diisocyanate (manufactured by Toso) and Takenate D110N (trimethylolpropane adduct form of xylylene diisocyanate, manufactured by Mitsui Kagaku).

Examples of the epoxy cross-linking agent include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, and trimethylolpropane triglycidyl ether. , Diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane.

From the viewpoint of ensuring the cohesive force of the pressure-sensitive adhesive layer 10, the blending amount of the cross-linking agent is, for example, 0.01 part by mass or more, preferably 0.05 part by mass or more, based on 100 parts by mass of the base polymer. It is preferably 0.07 parts by mass or more. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 10, the blending amount of the cross-linking agent with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass. It is as follows.

If a cross-linked structure is introduced into the base polymer, a cross-linking catalyst may be used to effectively proceed the cross-linking reaction. Examples of the cross-linking catalyst include dibutyltin dilaurate, tetra-n-butyl titanate, tetraisopropyl titanate, ferric nasem, and butyltin oxide, and dibutyltin dilaurate is preferably used. The amount of the cross-linking catalyst used is, for example, 0.0001 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the base polymer.

When a cross-linking catalyst is used, a cross-linking inhibitor that can be subsequently removed from the first sticky composition may be added to the first sticky composition. When dibutyltin dilaurate is used as the cross-linking catalyst, acetylacetone is preferably used as the cross-linking inhibitor. In this case, in the first adhesive composition, acetylacetone coordinates with dibutyltin dilaurate, and the cross-linking reaction of the cross-linking agent with the veil polymer is suppressed. In the manufacturing process described later for the pressure-sensitive adhesive sheet S, after the pressure-sensitive adhesive composition is applied onto the release film to form a coating film, acetylacetone can be volatilized and removed from the coating film by heating at a desired timing. This makes it possible to proceed with the cross-linking reaction of the cross-linking agent.

The blending amount of the crosslinking inhibitor is, for example, 100 parts by mass or more, preferably 1000 parts by mass or more with respect to 100 parts by mass of the crosslinking catalyst. The blending amount is, for example, 5000 parts by mass or less.

As described above, the monomer component (second monomer component) blended with the base polymer in the first adhesive composition contains an acid generator having a polymerizable functional group, and in the present embodiment, the polymerizable functional group is used. Further contains other compounds having (other polymerizable compounds). The polymerizable functional group has an ethylenically unsaturated double bond. Examples of the polymerizable functional group include a vinyl group such as a styrene group, a propenyl group, and a (meth) acryloyl group. The (meth) acryloyl group means an acryloyl group and / or a methacryloyl group. Preferred polymerizable functional groups from the viewpoint of reactivity include vinyl groups such as styrene groups and (meth) acryloyl groups.

The acid generator having a polymerizable functional group (first acid generator) is preferably a photoacid generator (first light) that generates an acid by being irradiated with active energy rays and has a polymerizable functional group. Acid generator) is used. The type of the active energy ray is determined by the type of the first photoacid generator (specifically, the wavelength of the active energy ray in which the first photoacid generator generates an acid). Examples of the active energy ray include ultraviolet rays, visible light, infrared rays, X-rays, α rays, β rays, and γ rays. From the viewpoint of variety of equipment used and ease of handling, the active energy ray preferably includes ultraviolet rays.

Examples of the first photoacid generator include an onium compound that generates an acid by irradiation with ultraviolet rays and has a polymerizable functional group. Onium compounds are provided, for example, in the form of onium salts of onium cations and anions. Examples of onium cations include iodonium and sulfonium. Examples of the anion include a sulfonic acid derivative anion, a sulfonimide derivative anion, and a sulfonmethide derivative anion. Preferably, the anion has a polymerizable functional group. As the first photoacid generator, an onium salt of a sulfonic acid derivative anion having a polymerizable functional group and sulfonium is preferably used, and more preferably, a sulfonic acid derivative anion having a (meth) acryloyl group and sulfonium. Onium salt is used, and more preferably triphenylsulfonium / 4-vinylbenzenesulfonate is used. A method for synthesizing this photoacid generator is described in, for example, “Novel Polymer anionic photoacid generators (PAGs) and corresponding polymers for 193 nm lithography” (Journal of Materials Chemistry, 2006, Vol. 16, p3701-3707). .. The first acid generator may be used alone or in combination of two or more.

The blending amount of the first acid generator with respect to 100 parts by mass of the color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, and further preferably 300 parts by mass or more. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

The blending amount of the first acid generator with respect to 100 parts by mass of the base polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 6 parts by mass or more. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

Examples of the other polymerizable compound contained in the second monomer component include a monomer having one polymerizable functional group (monofunctional monomer) and a monomer having a plurality of polymerizable functional groups (polyfunctional monomer). Can be mentioned.

Examples of the monofunctional monomer include ethyl (meth) acrylate, n-butyl (meth) acrylate, ter-butyl (meth) acrylate, isobutyl methacrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, and butoxydiethylene glycol (. Meta) acrylate, methoxypolyethylene glycol (meth) acrylate, glycidyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, cyclohexyl (meth) Meta) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) Meta) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , 2-Hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, trifluoroethyl (meth) acrylate, methacryloxyoxyethyl acid phosphate, 2-hydroxyethyl methacrylate phosphate, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, acryloylmorpholin, morpholinoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and N, N-dimethylamino Ethyl (meth) acrylate can be mentioned.

Examples of the polyfunctional monomer include a bifunctional monomer, a trifunctional monomer, and a tetrafunctional or higher polyfunctional monomer.

Examples of the bifunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethierlenglucol dimethacrylate, 1,6-hexanediol di (meth). Acrylate, 1,9-nonandiol di (meth) acrylate, glycerin di (meth) acrylate, neopentyl glycol di (meth) acrylate, stearic acid-modified pentaerythritol di (meth) acrylate, dicyclopentenyl diacrylate, di (meth) ) Acryloyl isocyanurate, and alkylene oxide-modified bisphenol di (meth) acrylates.

Examples of the trifunctional monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and tris (acryloyloxyethyl) isocyanate.

Examples of the tetrafunctional or higher polyfunctional monomer include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, alkyl-modified dipentaerythritol pentaacrylate, and dipentaerythritol pentaacrylate. Examples thereof include pentaerythritol hexa (meth) acrylate.

From the viewpoint of the quick-curing property of the pressure-sensitive adhesive layer 10, the other polymerizable compound is preferably a polyfunctional monomer, more preferably a tetrafunctional or higher polyfunctional monomer, and further preferably a dipentaerythritol hexa (meth) acrylate. Particularly preferably, dipentaerythritol hexaacrylate is used.

The blending amount of the second monomer component is preferably 5 parts by mass or more, more preferably 7 parts by mass with respect to 100 parts by mass of the base polymer from the viewpoint of ensuring sufficient hardness in the pressure-sensitive adhesive layer 10 after curing. The above is more preferably 9 parts by mass or more, and particularly preferably 10 parts by mass or more. From the viewpoint of ensuring sufficient adhesive strength in the cured pressure-sensitive adhesive layer 10, the blending amount of the polymerizable compound with respect to 100 parts by mass of the base polymer is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, still more preferably. Is 40 parts by mass or less.

In the present embodiment, the first adhesive composition further contains a photopolymerization initiator. The photopolymerization initiator is irradiated with active energy rays to initiate the polymerization reaction of the second monomer component. Examples of the photopolymerization initiator include a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, a photoactive oxime photopolymerization initiator, and a benzoin photopolymerization initiator. Examples thereof include an initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, a thioxanthone photopolymerization initiator, and an acylphosphine oxide photopolymerization initiator.

Examples of the color-developing compound (the first color-developing compound having no polymerizable functional group in the first adhesive composition) that develops color by reaction with an acid include leuco dye, triarylmethane dye, diphenylmethane dye, and fluorane dye. , Spiropyran dyes, and rhodamine dyes. The color-developing compound may be used alone or in combination of two or more.

Examples of leuco dyes include 2'-anilino-6'-(N-ethyl-N-isopentylamino) -3'-methylspiro [phthalide-3,9'-[9H] xanthene], 3-dibutylamino-. 6-Methyl-7-anilinofluorane, 3-dipropylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dimethylamino-6- Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, and 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole) -3-yl) -4-azaphthalide can be mentioned.

Examples of the triarylmethane dye include p, p', p "-tris-dimethylaminotriphenylmethane. Examples of the diphenylmethane dye include 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether. Examples of the fluorane dye include 3-diethylamino-6-methyl-7-chlorofluorane. Examples of the spiropyran dye include 3-methylspirodinaphthopyrane. Examples of the rhodamine dye include 3-methylspirodinaphthopyrane. For example, Rhodamine-B-anilinolactum can be mentioned.

From the viewpoint of ensuring good colorability in the pressure-sensitive adhesive layer 10, the first color-developing compound is preferably a leuco dye, more preferably 2'-anilino-6'-(N-ethyl-N-isopentylamino). ) -3'-Methylspiro [phthalide-3,9'-[9H] xanthene] is used.

The blending amount of the first color-developing compound with respect to 100 parts by mass of the base polymer is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. The blending amount is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

The first adhesive composition may contain other components, if necessary. Other components include, for example, silane coupling agents, tackifiers, plasticizers, softeners, antioxidants, surfactants, and antistatic agents.

The second adhesive composition has the same composition as described above with respect to the first adhesive composition, except for the following. In the second adhesive composition, the second monomer component is a color-developing compound having a polymerizable functional group and developing a color by reaction with an acid instead of the first acid generator having a polymerizable functional group (second). Color-developing compound) is included. The second tacky composition contains an acid generator (second acid generator) having no polymerizable functional group in place of the first color-developing compound having no polymerizable functional group.

Examples of the second color-developing compound (having a polymerizable functional group) include a leuco dye having a polymerizable functional group, a triarylmethane dye having a polymerizable functional group, a diphenylmethane dye having a polymerizable functional group, and a polymerizable functional group. Examples thereof include a fluorane dye having a group, a spiropyran dye having a polymerizable functional group, and a rhodamine dye having a polymerizable functional group. The polymerizable functional group has an ethylenically unsaturated double bond. Examples of the polymerizable functional group include a vinyl group, a propenyl group, and a (meth) acryloyl group. The (meth) acryloyl group means an acryloyl group and / or a methacryloyl group. From the viewpoint of reactivity, it is preferable to use a compound having a (meth) acryloyl group as the polymerizable functional group as the second monomer component. The second color-developing compound may be used alone or in combination of two or more. As the second color-developing compound, a leuco dye having a polymerizable functional group is preferably used, a leuco dye having a (meth) acryloyl group is more preferably used, and a leuco dye having an acryloyl group is more preferably used. Be done. Examples of the leuco dye having a polymerizable functional group include the acryloyl group-containing leuco dye described in International Publication No. 2013/048993.

The secondary acid generator (which does not have a polymerizable functional group) is preferably a photoacid generator (which does not have a polymerizable functional group) that generates an acid when irradiated with active energy rays. Agent) is used. Examples of the second photoacid generator include an onium compound that generates an acid by irradiation with ultraviolet rays. Onium compounds are provided, for example, in the form of onium salts of onium cations and anions. Examples of onium cations include iodonium and sulfonium. Examples of anions include ^{Cl- ,} Br- ^, I- ^, ZnCl _3- ^, HSO _3- ^, BF _4- ^, PF _6- ^, AsF _6- ^, SbF _6- ^, CH ₃ SO _3- ^, CF ₃ SO _3- . , C ₄ F ₉ HSO _3- ^, (C ₆ F ₅ ) ₄ B- ^, and (C ₄ H ₉ ⁾ ₄ B-. The second photoacid generator may be used alone or in combination of two or more. The second tacky composition preferably contains an onium salt (onium compound) composed of sulfonium ^and C ₄ F ₉ HSO _3- as the second photoacid generator.

In the second adhesive composition, the blending amount of the second acid generator with respect to 100 parts by mass of the second color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 300 parts by mass or more. Is. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

In the second adhesive composition, the blending amount of the second acid generator with respect to 100 parts by mass of the base polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably. Is 6 parts by mass or more. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

The third adhesive composition has the same composition as described above with respect to the first adhesive composition, except for the following. In the third tacky composition, the second monomer component further contains a second color-developing compound which has a polymerizable functional group and develops a color by reaction with an acid. In the present embodiment, the third tacky composition does not substantially contain the first color-developing compound having no polymerizable functional group.

Examples of the second color-developing compound in the third adhesive composition include the above-mentioned compounds as the second color-developing compound in the second adhesive composition.

In the third adhesive composition, the blending amount of the first acid generator with respect to 100 parts by mass of the second color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 300 parts by mass or more. Is. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

The fourth adhesive composition has the same composition as described above with respect to the first adhesive composition, except for the following. In the fourth tacky composition, the monomer component (first monomer component) forming the base polymer contains an acid generator (first acid generator) having a polymerizable functional group. The fourth sticky composition does not substantially contain the second monomer component in the present embodiment.

Examples of the first acid generator in the fourth sticky composition include the above-mentioned compounds as the first acid generator in the first sticky composition.

In the fourth adhesive composition, the blending amount of the first acid generator with respect to 100 parts by mass of the first color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 300 parts by mass or more. Is. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

The blending amount of the first acid generator in 100 parts by mass of the first monomer component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 6 parts by mass or more. be. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

The fifth adhesive composition has the same composition as described above with respect to the first adhesive composition, except for the following. In the fifth adhesive composition, the monomer component (first monomer component) forming the base polymer contains a color-developing compound (second color-developing compound) having a polymerizable functional group. The fifth tacky composition contains a second acid generator having no polymerizable functional group in place of the first color-developing compound having no polymerizable functional group. The fifth sticky composition does not substantially contain the second monomer component in the present embodiment.

Examples of the second color-developing compound in the fifth adhesive composition include the above-mentioned compounds as the second color-developing compound in the second adhesive composition. Examples of the second acid generator in the fifth sticky composition include the above-mentioned compounds as the second acid generator in the second sticky composition.

In the fifth adhesive composition, the blending amount of the second acid generator (having no polymerizable functional group) with respect to 100 parts by mass of the second color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass. The above is more preferably 300 parts by mass or more. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

In the fifth adhesive composition, the blending amount of the secondary acid generator with respect to 100 parts by mass of the base polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably. Is 6 parts by mass or more. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

The sixth adhesive composition has the same composition as described above with respect to the first adhesive composition, except for the following. In the sixth adhesive composition, the monomer component (first monomer component) forming the base polymer has an acid generator having a polymerizable functional group (first acid generator) and a color-developing property having a polymerizable functional group. Contains a compound (second color-developing compound). In the present embodiment, the sixth tacky composition does not substantially contain the second monomer component and the first color-developing compound having no polymerizable functional group.

Examples of the first acid generator in the sixth sticky composition include the above-mentioned compounds as the first acid generator in the first sticky composition. Examples of the second color-developing compound in the sixth adhesive composition include the above-mentioned compounds as the second color-developing compound in the second adhesive composition.

In the sixth adhesive composition, the blending amount of the first acid generator with respect to 100 parts by mass of the second color-developing compound is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 300 parts by mass or more. Is. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, and further preferably 500 parts by mass or less.

The blending amount of the first acid generator in 100 parts by mass of the first monomer component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 6 parts by mass or more. be. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less.

For the pressure-sensitive adhesive sheet S, for example, the above-mentioned first, second, third, fourth, fifth, or sixth adhesive composition was applied onto a release film (first release film) to form a coating film. After that, it can be manufactured by drying the coating film (in FIG. 1, the adhesive sheet S is arranged on the release film L shown by the virtual line).

Examples of the release film include a flexible plastic film. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. The thickness of the release film is, for example, 3 μm or more, and is, for example, 200 μm or less. The surface of the release film is preferably mold-released.

Examples of the method of applying the adhesive composition include roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, and lip coat. , And die coat. The drying temperature of the coating film is, for example, 50 ° C to 200 ° C. The drying time is, for example, 5 seconds to 20 minutes.

When the tacky composition contains a cross-linking agent, the cross-linking reaction proceeds by aging at the same time as or after the above-mentioned drying. The aging conditions are appropriately set depending on the type of the cross-linking agent. The aging temperature is, for example, 20 ° C to 160 ° C. The aging time is, for example, 1 minute to 7 days.

Further, the release film (second release film) may be further laminated on the pressure-sensitive adhesive layer 10 on the first release film before or after aging. The second release film is a flexible plastic film that has been subjected to a surface release treatment, and the same film as described above can be used for the first release film.

As described above, the pressure-sensitive adhesive sheet S whose adhesive surface is covered and protected by the release film can be manufactured. Each release film is peeled off from the pressure-sensitive adhesive sheet S as needed when using the pressure-sensitive adhesive sheet S.

The thickness of the pressure-sensitive adhesive layer 10 is preferably 10 μm or more, more preferably 15 μm or more, from the viewpoint of ensuring sufficient adhesiveness to the adherend. From the viewpoint of handleability of the pressure-sensitive adhesive sheet S, the thickness of the pressure-sensitive adhesive layer 10 is preferably 300 μm or less, more preferably 200 μm or less, still more preferably 100 μm or less, and particularly preferably 50 μm or less.

The haze of the pressure-sensitive adhesive layer 10 is preferably 3% or less, more preferably 2% or less, and more preferably 1% or less. Such a configuration is suitable for inspecting the presence or absence of foreign matter and air bubbles between the pressure-sensitive adhesive sheet S and the adherend after the pressure-sensitive adhesive sheet S is attached to the adherend. The haze of the pressure-sensitive adhesive layer 10 can be measured using a haze meter in accordance with JIS K7136 (2000). Examples of the haze meter include "NDH2000" manufactured by Nippon Denshoku Kogyo Co., Ltd. and "HM-150 type" manufactured by Murakami Color Technology Research Institute.

The average transmittance of the pressure-sensitive adhesive layer 10 at a wavelength of 400 to 700 nm (the average transmittance before applying a second external stimulus to the pressure-sensitive adhesive layer 10) is preferably 80% or more, more preferably 85% or more, still more preferably. 90% or more. Such a configuration is suitable for inspecting the presence or absence of foreign matter and air bubbles between the pressure-sensitive adhesive sheet S and the adherend after the pressure-sensitive adhesive sheet S is attached to the adherend.

The adhesive force exhibited by the adhesive sheet S on the stainless steel plate in a peeling test under the peeling conditions of 23 ° C., a peeling angle of 180 ° and a peeling speed of 300 mm / min after being bonded to the glass plate is, for example, 1 N / 25 mm or more. It is, for example, 50 N / 25 mm or less.

When the pressure-sensitive adhesive layer 10 is formed from the first, second or third pressure-sensitive adhesive composition and contains both a photoacid generator and a photopolymerization initiator, the pressure-sensitive adhesive layer 10 is preferably light. A wavelength region in which the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the acid generator is 2 or more is in the range of a wavelength of 300 nm or more and 500 nm or less. The ratio is preferably 3 or more, more preferably 10 or more, still more preferably 50 or more, and particularly preferably 100 or more. The same ratio is, for example, 1 million or less.

As shown in FIG. 2, the pressure-sensitive adhesive sheet S may be a single-sided pressure-sensitive adhesive sheet with a base material, which comprises a base material 20 in addition to the pressure-sensitive adhesive layer 10. In this case, the pressure-sensitive adhesive sheet S specifically includes a pressure-sensitive adhesive layer 10 and a base material 20 arranged on one side in the thickness direction thereof. Preferably, the substrate 20 contacts one side of the pressure-sensitive adhesive layer 10 in the thickness direction.

The base material 20 is an element that functions as a transparent support. The base material 20 is, for example, a flexible plastic film. Examples of the constituent material of the plastic film include polyolefin, polyester, polyamide, polyimide, polyvinyl chloride, polyvinylidene chloride, cellulose, polystyrene, and polycarbonate. Examples of the polyolefin include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, and the like. Examples thereof include an ethylene / ethyl acrylate copolymer and an ethylene / vinyl alcohol copolymer. Examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Examples of the polyamide include polyamide 6, polyamide 6, 6 and partially aromatic polyamide. From the viewpoint of achieving both transparency and mechanical strength of the base material 20, the plastic material of the base material 20 is preferably polyester, more preferably polyethylene terephthalate.

The base material 20 has transparency. The haze of the base material 20 is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less. The haze of the base material 20 can be measured using a haze meter in accordance with JIS K7136 (2000).

The surface of the base material 20 on the pressure-sensitive adhesive layer 10 side may be subjected to a physical treatment, a chemical treatment, or an undercoating treatment for enhancing the adhesion to the pressure-sensitive adhesive layer 10. Physical treatments include, for example, corona treatment and plasma treatment. Examples of the chemical treatment include acid treatment and alkali treatment.

The thickness of the base material 20 is preferably 5 μm or more, more preferably 10 μm or more, and more preferably 20 μm or more from the viewpoint of ensuring the strength for the base material 20 to function as a support. Further, from the viewpoint of realizing appropriate flexibility in the pressure-sensitive adhesive sheet S, the thickness of the base material 20 is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less.

The pressure-sensitive adhesive sheet S shown in FIG. 2 can be manufactured by the same method as the above-mentioned pressure-sensitive adhesive sheet manufacturing method except that the base material 20 is used instead of the first release film, for example.

FIG. 3 shows an example of how to use the adhesive sheet S. The method includes a preparation step, a joining step, and a discolored portion forming step.

First, in the preparation step, as shown in FIG. 3A, the adhesive sheet S, the first member 31, and the second member 32 are prepared. The first member 31 is, for example, a display panel such as an organic EL panel. The first member 31 may be another electronic device or an optical device. The second member 32 is, for example, a transparent base material. Examples of the transparent base material include a transparent plastic base material and a transparent glass base material.

Next, in the joining step, as shown in FIG. 3B, the first member 31 and the second member 32 are joined via the pressure-sensitive adhesive sheet S. As a result, the laminated body Z is obtained. In the laminated body Z, the adhesive sheet S is arranged so as to be in contact with one surface in the thickness direction of the first member 31, and the second member 32 is arranged so as to be in contact with one surface in the thickness direction of the adhesive sheet S. Will be done.

After the joining step, if necessary, the presence or absence of foreign matter and air bubbles between the members 31, 32 and the pressure-sensitive adhesive sheet S is inspected.

In the pressure-sensitive adhesive sheet S provided with the pressure-sensitive adhesive layer 10 formed from the first, second or third pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer 10 is then cured (curing step) as shown in FIG. 3C. Specifically, the pressure-sensitive adhesive layer 10 in the laminate Z (in the case of performing the above inspection, the laminate Z that has passed the inspection) is irradiated with active energy rays to promote the polymerization reaction of the second monomer component. ..

The active energy ray of this step is applied to the pressure-sensitive adhesive layer 10 from the side of the transparent second member 32. Examples of the light source for irradiating the active energy ray in this step include an ultraviolet LED light, a black light, a high-pressure mercury lamp, and a metal halide lamp. Further, in the activation energy ray irradiation in this step, a wavelength cut filter for cutting a part of the wavelength region in the active energy ray emitted from the light source may be used as needed.

The active energy ray (first active energy ray) has a different wavelength range from the above-mentioned active energy ray (second active energy ray) for generating an acid from an acid generator. In the present embodiment, the first active energy ray has a wavelength that does not substantially generate an acid in the acid generator. The lower limit of the wavelength range of the first active energy ray is preferably 365 nm, more preferably 370 nm, still more preferably 375 nm, still more preferably 380 nm, still more preferably 385 nm, still more preferably 390 nm, and particularly preferably 395 nm. In the present embodiment, preferably, a photopolymerization initiator that initiates the polymerization reaction of the second monomer component by being irradiated with active energy rays having such a wavelength is blended in the pressure-sensitive adhesive layer 10.

In this step, in the pressure-sensitive adhesive layer 10 irradiated with the first active energy ray, the polymerization reaction of the second monomer component is started by the photopolymerization initiator, and the polymerization reaction proceeds. As a result, the elastic modulus of the pressure-sensitive adhesive layer 10 increases.

As described above, the pressure-sensitive adhesive layer 10 has a wavelength region (wavelength region R) in which the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the photoacid generator is 2 or more within the range of a wavelength of 300 nm or more and 500 nm or less. It is preferable to have it in. The ratio (Y / X) in the wavelength region R is preferably 3 or more, more preferably 10 or more, and further preferably 100 or more. Preferably, at least a part of the wavelength of the first active energy ray to be irradiated is in the wavelength region R. More preferably, all the wavelengths of the first active energy rays to be irradiated are within the wavelength region R. The configuration in which the pressure-sensitive adhesive layer 10 is irradiated with the first active energy ray having a wavelength within the wavelength region is such that the pressure-sensitive adhesive layer 10 is cured while suppressing discoloration in the pressure-sensitive adhesive layer 10 in the curing step. Suitable. From the viewpoint of curing the pressure-sensitive adhesive layer 10 while suppressing discoloration in the pressure-sensitive adhesive layer 10 in the curing step, the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the photoacid generator is larger. preferable.

Next, in the discoloration portion forming step, as shown in FIG. 3D, the second active energy ray is irradiated to the planned discoloration portion in the pressure-sensitive adhesive layer 10 of the laminated body Z to form the discoloration portion 11 in the pressure-sensitive adhesive layer 10. .. Specifically, the second active energy ray is sent to the pressure-sensitive adhesive layer 10 from the side of the transparent second member 32 via a mask pattern (not shown) for masking a predetermined region in the pressure-sensitive adhesive layer 10. Irradiate. As a result, the portion of the pressure-sensitive adhesive layer 10 that is not masked by the mask pattern is discolored.

Examples of the light source for irradiating the second active energy ray include an ultraviolet LED light, a black light, a high-pressure mercury lamp, and a metal halide lamp. Further, in the second active energy ray irradiation, a wavelength cut filter for cutting a part of the wavelength region in the active energy ray emitted from the light source may be used, if necessary.

The wavelength range of the second active energy ray is different from that of the above-mentioned first active energy ray. The wavelength range of the second active energy ray preferably includes at least a range smaller than the wavelength range of the first active energy ray (wavelength range on the short wavelength side) (the wavelength range of the second active energy ray is the first active energy). It may include a range that overlaps with the wavelength range of the line). When the second active energy ray has a lower limit in the wavelength range, or when the lower limit is set in the wavelength range of the second active energy ray by using, for example, a wavelength cut filter, the lower limit of the wavelength range of the second active energy ray is set. It is preferably 300 nm, more preferably 305 nm, more preferably 310 nm, still more preferably 315 nm, still more preferably 320 nm, still more preferably 325 nm, and particularly preferably 330 nm. Alternatively, the second active energy ray may contain light having a wavelength of less than 300 nm. Light sources of such light include, for example, high pressure mercury lamps and metal halide lamps. When the second active energy ray has an upper limit in the wavelength range, or when the upper limit is set in the wavelength range of the second active energy ray by using, for example, a wavelength cut filter, the upper limit of the wavelength range of the second active energy ray is It is preferably 400 nm, more preferably 395 nm, still more preferably 390 nm, even more preferably 385 nm, still more preferably 380 nm, still more preferably 375 nm, and particularly preferably 370 nm. In the present embodiment, preferably, a photoacid generator that generates an acid by being irradiated with active energy rays having such a wavelength is blended in the pressure-sensitive adhesive layer 10.

In this step, an acid is generated from the photoacid generator at the portion of the pressure-sensitive adhesive layer 10 that has been irradiated with the second active energy ray, and the color-developing compound is developed by the reaction with the acid. As a result, the discolored portion 11 is formed on the pressure-sensitive adhesive layer 10.

For example, as described above, the adhesive sheet S can be used for joining the members. When the first member 31 is a display panel such as an organic EL panel, the metal is provided by providing the discolored portion 11 in a pattern shape corresponding to (that is, facing) the metal wiring formed on the pixel panel included in the panel. External light reflection in wiring can be suppressed.

In the pressure-sensitive adhesive sheet S, the pressure-sensitive adhesive layer 10 (the pressure-sensitive adhesive layer formed from the above-mentioned first, second, third, fourth, fifth or sixth pressure-sensitive adhesive composition) develops color by reaction with an acid. The color-developing compound and the acid generator are contained in the above-mentioned predetermined embodiments. Therefore, after the pressure-sensitive adhesive sheet S is attached to the adherend, acid is generated from the acid generator in the part to be discolored (at least a part of the pressure-sensitive adhesive layer 10) of the pressure-sensitive adhesive layer 10 by applying an external stimulus to the portion. The acid can be used to develop a color-developing compound. According to such a pressure-sensitive adhesive sheet S, the presence or absence of foreign matter and air bubbles between the sheet and the adherend can be inspected after the bonding and before the formation of the discolored portion of the pressure-sensitive adhesive layer 10.

Further, in the pressure-sensitive adhesive layer 10 of the pressure-sensitive adhesive sheet S, at least one of a color-developing compound and an acid generator that develops color by reaction with an acid can be copolymerized in a state of being incorporated in a base polymer or as a second monomer component. (In the latter state, at least one of the color-developing compound and the acid generator is incorporated into the polymer network by undergoing a polymerization reaction of the second monomer component in the pressure-sensitive adhesive layer 10. Can be done). In such a pressure-sensitive adhesive sheet S, after the discolored portion is formed in the pressure-sensitive adhesive layer 10 (that is, after the color-developing compound is colored by the reaction with the acid derived from the acid generator), the color-developing compound is diffused. Suitable for suppressing. By suppressing the diffusion of the color-developing compound, deterioration of the discolored portion (bleeding, fading, non-uniformity of color, etc.) is suppressed.

As described above, the pressure-sensitive adhesive sheet S can discolor at least a part of the pressure-sensitive adhesive layer 10 after being attached to the adherend, and is suitable for suppressing deterioration of the discolored portion of the pressure-sensitive adhesive layer 10. Suppressing the deterioration of the discolored portion in the pressure-sensitive adhesive layer 10 is useful for maintaining the functional characteristics of the discolored portion such as designability, shielding property, and antireflection property.

In the above embodiments, the fourth, fifth and sixth sticky compositions are the other polymerizable compounds (monofunctional monomer and poly) described above with respect to the second monomer component of the first to third sticky compositions, respectively. It may contain, for example, a functional monomer) together with a photopolymerization initiator. In addition, the fourth, fifth, and sixth adhesive compositions may each contain the above-mentioned first acid generator and / or second color-developing compound as the second monomer component.

According to the pressure-sensitive adhesive sheet S provided with the pressure-sensitive adhesive layer 10 formed from such a fourth, fifth or sixth pressure-sensitive adhesive composition, the above-mentioned curing step can be carried out with reference to FIG. 3C. Specifically, the pressure-sensitive adhesive layer 10 in the laminated body Z is irradiated with active energy rays to promote the polymerization reaction of the second monomer component, and the elastic modulus of the pressure-sensitive adhesive layer 10 can be increased.

In addition, the first and fourth adhesive compositions may each contain the above-mentioned second acid generator. The second and fifth adhesive compositions may each contain the above-mentioned first color-developing compound. The third and sixth sticky compositions may contain a second acid generator and a first color-developing compound, respectively.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), the physical property value, the parameter, etc. described below are the compounding amounts corresponding to them described in the above-mentioned "form for carrying out the invention" (forms for carrying out the invention). It can be replaced with an upper limit (numerical value defined as "less than or equal to" or "less than") or a lower limit (numerical value defined as "greater than or equal to" or "greater than or equal to") such as content), physical property value, and parameter.

[Example 1]
<Preparation of base polymer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen gas introduction tube, 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of methyl methacrylate (MMA), and 2-acrylic acid. 13 parts by mass of hydroxyethyl (HEA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator. The mixture containing 233 parts by mass of ethyl acetate as a solvent was stirred at 60 ° C. for 7 hours under a nitrogen atmosphere (polymerization reaction). As a result, a polymer solution containing an acrylic polymer (polymer solution P ₁ ) was obtained. The weight average molecular weight (Mw) of the acrylic polymer in this polymer solution P1 was _1.2 million.

<Preparation of adhesive composition>
In a polymer solution P1 containing an acrylic polymer, an isocyanate cross-linking agent as a cross-linking agent (trade name "Takenate D110N", 75% acetic acid of a trimethylol propan adduct of xylylene diisocyanate) _per 100 parts by mass of the acrylic polymer (base polymer). Ethyl solution, manufactured by Mitsui Chemicals, Inc. 0.25 parts by mass (solid content equivalent amount) and dibutyltin dilaurate as a cross-linking catalyst (trade name "OL-1", 1 mass% ethyl acetate solution, manufactured by Tokyo Fine Chemicals Co., Ltd.) 0. 01 parts by mass (solid content equivalent amount), 3 parts by mass of acetylacetone as a cross-linking inhibitor (ligand to a cross-linking catalyst), and leuco dye as a color-developing compound (trade name "S-205", 2'-anilino) -6'-(N-ethyl-N-isopentylamino) -3'-methylspiro [phthalide-3,9'-[9H] xanthene], manufactured by Yamada Chemical Industry Co., Ltd.) and a monomer copolymerizable with 2 parts by mass. Ingredient (second monomer component) 30.75 parts by mass and photopolymerization initiator (trade name "Omnirad 819", bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, manufactured by IGM Resins BV) 0.38 Parts by weight were added and mixed to prepare a tacky composition. The second monomer component is 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 22.5 parts by mass as a monofunctional monomer and dipenta as a polyfunctional monomer per 100 parts by mass of an acrylic polymer (base polymer). It contains 2 parts by mass of erythritol hexaacrylate (manufactured by Dycel Ornex) and 6.25 parts by mass of triphenylsulfonium / 4-vinylbenzenesulfonate as a photoacid generator having a polymerizable functional group.

<Formation of adhesive layer>
An adhesive composition was applied by a fountain roll onto a 38 μm-thick polyethylene terephthalate film (base film) whose surface had been mold-released to form a coating film. The coating was then dried by heating at 132 ° C. for 3 minutes. As a result, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the base film. Next, a mold release-treated surface of a separator (a polyethylene terephthalate film having a thickness of 38 μm whose one side was mold-released) was attached to the pressure-sensitive adhesive layer on the base film. Then, it was aged at 60 ° C. for 24 hours to allow the cross-linking reaction in the pressure-sensitive adhesive layer to proceed. As described above, the pressure-sensitive adhesive sheet of Example 1 was produced.

[Example 2]
<Synthesis of leuco dye containing polymerizable functional group>
First, 5.5 mL of 3-methyl-4-aminophenol methyl ether was added dropwise to 40 g of concentrated sulfuric acid (97%) in a flask while stirring the concentrated sulfuric acid. Next, 16.4 g of 2- (2-hydroxy-4-dimethylamino) benzoylbenzoic acid was added to the resulting mixture. The resulting mixture was then stirred at 35 ° C. for 72 hours. The mixture was then added slowly into a 1 L flask containing 320 g of ice. Next, 290 g of 11% sodium hydroxide solution was added to the flask. The resulting mixture was then stirred at 96 ° C. for 4 hours. Next, 80 mL of toluene was added to the mixture, and then the mixture was stirred at 96 ° C. for 2 hours. Next, after allowing the reaction solution to stand for 30 minutes, the organic layer formed as the upper layer of the reaction solution was collected in the flask using a pipette. Next, the contents of the flask were cooled in a water bath at 3.5 ° C. for 30 minutes. Next, the contents were filtered through a filter paper (opening size 2.5 μm) and then washed with 5 mL of toluene. Next, the filtrate was dried under vacuum at 65 ° C. for 4 hours to obtain 5.2 g of compound P represented by the following chemical formula ( ₁ ). Next, 2.4 g of compound P ₁ was placed in a flask with 30 mL of tetrahydrofuran, 2 mL of dimethylformamide, and 2 mL of triethylamine. Next, 0.64 mL of acryloyl chloride was added little by little to the mixture in the flask, and then the mixture was stirred at room temperature for 24 hours. The resulting mixture was then poured into 20 mL of ion-exchanged water. Next, the precipitate formed thereby was filtered through a filter paper (opening size 2.5 μm). Next, the solid substance (filter) was dried under vacuum at room temperature for 72 hours to obtain compound P ₂ (leuco dye having a polymerizable functional group) represented by the following chemical formula (2).

<Preparation of base polymer>
In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen gas introduction tube, 68 parts by mass of 2-ethoxymethyl acrylate, 10 parts by mass of 4-hydroxybutyl acrylate (4HBA), and N-vinyl. -2-Pyrrolidone (NVP) 15 parts by mass, 2 parts by mass of the leuco dye (Compound P ₂ ) having a polymerizable functional group, and 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator. A mixture containing 0.2 parts by mass and 210 parts by mass of ethyl acetate as a solvent was stirred at 60 ° C. for 7 hours under a nitrogen atmosphere (polymerization reaction). As a result, a polymer solution containing an acrylic polymer (polymer solution P ₂ ) was obtained. The weight _average molecular weight (Mw) of the acrylic polymer in this polymer solution P2 was 240,000.

<Preparation of adhesive composition>
_In a polymer solution P2 containing an acrylic polymer, 0.25 parts by mass (solid content equivalent) of an isocyanate cross-linking agent (trade name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent per 100 parts by mass of the acrylic polymer (base polymer). Amount), 0.01 parts by mass (solid content equivalent amount) of dibutyltin dilaurate (trade name "OL-1", manufactured by Tokyo Fine Chemicals Co., Ltd.) as a cross-linking catalyst, 3 parts by mass of acetylacetone as a cross-linking inhibitor, and light. An acid generator (trade name "CPI-310B", onium salt of sulfonium ^and (C ₆ F ₅ ) ₄ B-, manufactured by San-Apro Co., Ltd.) was added and mixed by 7 parts by mass to prepare a tacky composition.

<Formation of adhesive layer>
An adhesive composition was applied by a fountain roll onto a 38 μm-thick polyethylene terephthalate film (base film) whose surface had been mold-released to form a coating film. The coating was then dried by heating at 132 ° C. for 3 minutes. As a result, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the base film. Next, the mold release-treated surface of the separator (a polyethylene terephthalate film having a thickness of 38 μm on which one surface was mold-released) was attached to the pressure-sensitive adhesive layer on the base film. Then, it was aged at 60 ° C. for 24 hours to allow the cross-linking reaction in the pressure-sensitive adhesive layer to proceed. As described above, the pressure-sensitive adhesive sheet of Example 2 was produced.

[Comparative Example 1]
The pressure-sensitive adhesive sheet of Comparative Example 1 was produced in the same manner as the pressure-sensitive adhesive sheet of Example 1 except for the following.

In the preparation of the tacky composition, diphenyl-2,4,6-trimethylphenyl as a photoacid generator having no polymerizable functional group instead of 6.25 parts by mass of the photoacid generator containing a polymerizable functional group. 6.25 parts by mass of sulfonium p-toluene sulfonate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was used.

<Durability test>
With respect to the pressure-sensitive adhesive layer of each of the pressure-sensitive adhesive sheets of Examples 1 and 2 and Comparative Example 1, the degree of suppression of bleeding of the discolored portion formed was examined as follows.

First, a plurality of pressure-sensitive adhesive sheets were prepared for each of the pressure-sensitive adhesive sheets of Examples 1 and 2 and Comparative Example 1.

Next, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was irradiated with ultraviolet rays in an environment of 23 ° C. and a relative humidity of 50% (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of Example 1 was cured by the UV irradiation). In this ultraviolet irradiation, a UV-LED lamp having a wavelength of 405 nm in a UV-LED irradiation device (model number "QEL-350-RU6W-CW-MY") manufactured by Quark Technology Co., Ltd. is used as a light source, and an adhesive is applied through the base film. The layer was irradiated with ultraviolet rays, and the integrated irradiation light amount was set to 2000 mJ / cm ² (the integrated irradiation light amount in the wavelength range of 395 to 445 nm).

Next, a linear discolored portion was formed on the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with ultraviolet rays through a photomask having a linear opening. The photomask is formed of a dry film photoresist arranged on the surface of the pressure-sensitive adhesive sheet on the base film side, and the line width of the opening of the photomask is about 230 to 270 μm (the line width of the opening is the photomask). Different for each). For ultraviolet irradiation, a UV-LED lamp with a wavelength of 365 nm in a UV-LED irradiation device (model number "QEL-350-RU6W-CW-MY") manufactured by Quark Technology Co., Ltd. is used as a light source through a photo mask and a base film. The pressure-sensitive adhesive layer was irradiated with ultraviolet rays, and the integrated irradiation light amount was set to 2000 mJ / cm ² (the integrated irradiation light amount in the wavelength range of 320 to 390 nm).

Next, the line width of the linear discolored portion formed on the pressure-sensitive adhesive layer was measured (measurement of the initial line width). Specifically, first, the linear discolored portion formed on the adhesive layer is observed with a digital microscope (trade name "VHX-900", manufactured by KEYENCE), and a part of the discolored portion and its vicinity are observed. The area to be included was photographed at a magnification of 50 times. Next, the captured image was binarized by image analysis software. Next, in the image after the binarization process, the line width (W1) of the linear discolored portion was measured.

Next, the pressure-sensitive adhesive sheet having the linear discolored portion formed on the pressure-sensitive adhesive layer was heat-treated at 85 ° C. for 120 hours (durability test).

Next, the line width of the linear discolored portion in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was measured. The specific measurement method is the same as the measurement method described above for the measurement of the initial line width. Table 1 shows the line width W1 of the linear discolored portion before the durability test, the line width W2 of the linear discolored portion after the durability test, and the rate of increase (W2 / W1) of the line width W2 with respect to the line width W1. Shown in.

The rate of increase in the line width (W2 / W1) of the linearly discolored portion after the durability test was smaller in each of the pressure-sensitive adhesive sheets of Examples 1 and 2 than that of the pressure-sensitive adhesive sheet of Comparative Example 1. That is, in each of the pressure-sensitive adhesive sheets of Examples 1 and 2, bleeding of the discolored portion of the pressure-sensitive adhesive layer was suppressed as compared with the pressure-sensitive adhesive sheet of Comparative Example 1.

S Adhesive sheet (variable color adhesive sheet)
10 Adhesive layer 11 Discolored part 20 Base material 31 First member 32 Second member

Claims (5)

It comprises a pressure-sensitive adhesive layer containing a base polymer and a monomer component, or a polymer of the monomer component as a base polymer.
The monomer component contains an acid generator having a polymerizable functional group, and the pressure-sensitive adhesive layer further contains a color-developing compound that develops color by reaction with an acid, or
The monomer component contains a color-developing compound having a polymerizable functional group and developing a color by reaction with an acid, and the pressure-sensitive adhesive layer further contains an acid generator, or
A variable color pressure-sensitive adhesive sheet, wherein the monomer component contains an acid generator having a polymerizable functional group and a color-developing compound having a polymerizable functional group and developing a color by reaction with an acid. The variable according to claim 1, wherein the content of the monomer component in the pressure-sensitive adhesive layer containing the base polymer and the monomer component is 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base polymer. Color adhesive sheet. The pressure-sensitive adhesive layer containing the base polymer and the monomer component further contains a photopolymerization initiator.
The acid generator is a photoacid generator and is
The variable color adhesion according to claim 1 or 2, wherein the wavelength region in which the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the photoacid generator is 2 or more is within the wavelength range of 300 nm or more and 500 nm or less. Sheet. The variable color pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a thickness of 10 μm or more and 300 μm or less. The variable color pressure-sensitive adhesive sheet according to any one of claims 1 to 4, further comprising a base material arranged on one side in the thickness direction of the pressure-sensitive adhesive layer.

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