KR102572377B1 - variable color adhesive sheet - Google Patents

Abstract

The pressure-sensitive adhesive sheet (S) as a variable color pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer (10). The pressure-sensitive adhesive layer 10 contains a base polymer and a monomer component, or contains a polymer of the monomer component as a base polymer. In the pressure-sensitive adhesive sheet S, the monomer component contains an acid generator having a polymerizable functional group, and the pressure-sensitive adhesive layer 10 contains a color-developing compound that develops color by reaction with an acid. Alternatively, the monomer component contains a color-developing compound that has a polymerizable functional group and develops color by reaction with an acid, and the pressure-sensitive adhesive layer 10 contains an acid generator. Alternatively, the monomer component includes an acid generator having a polymerizable functional group and a color-developing compound having a polymerizable functional group and developing color by reaction with an acid.

Description

variable color adhesive sheet

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 manufacturing process of such a display panel, for example, a transparent adhesive sheet is used for bonding the elements included in the laminated structure.

In addition, as a transparent adhesive sheet disposed on the light output side (image display side) of a pixel panel in a display panel, a colored portion for imparting design, shielding, antireflection, etc. to a predetermined portion of the sheet is formed in advance. It has been proposed to use a pressure-sensitive adhesive sheet. Such an adhesive sheet is described, for example, in Patent Literature 1 below. Patent Literature 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 case of using a PSA sheet having pre-formed colored portions in the manufacturing process of the display panel, after bonding the PSA sheet to the adherend, foreign matter and air bubbles between the adherend and the colored portion of the PSA sheet are removed. The presence or absence cannot be properly checked. In bonding of the adhesive sheet in the display panel manufacturing process, it is required to be able to properly 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 securing the function of the colored portion provided on the transparent adhesive sheet for display panels, it is required that the deterioration of the colored portion be suppressed.

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

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

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, [1 ].

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 absorbance X of the photoacid generator is described above. It includes the variable color adhesive sheet according to [1] or [2] above, which has a wavelength region in which the ratio of absorbance Y of the photopolymerization initiator is 2 or more within a wavelength range of 300 nm or more and 500 nm or less.

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

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

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-described specific aspect. Therefore, after bonding the variable color PSA sheet to the adherend, an acid is generated from an acid generator by applying an external stimulus to the portion where the color change is expected (at least a part of the PSA layer) of the PSA layer, A color developing compound can be made to develop color with the said acid. According to such a color-changing pressure-sensitive adhesive sheet, the presence or absence of foreign substances and air bubbles between the sheet and the adherend can be inspected after bonding and before formation of the discolored portion of the pressure-sensitive adhesive layer.

In addition, as described above, the pressure-sensitive adhesive layer of the variable color pressure-sensitive adhesive sheet contains at least one of a color-developing compound that develops color by reaction with an acid and an acid generator in a state in which the base polymer is incorporated or in a state in which it can be copolymerized as a monomer component. (In the case of taking the latter state, at least one of the color-developing compound and the acid generator can be incorporated into the polymer network by undergoing a polymerization reaction of the monomer components in the pressure-sensitive adhesive layer). Such a color-changing pressure-sensitive adhesive sheet is suitable for suppressing diffusion of a color-developing compound after a color-changing portion is formed in the pressure-sensitive adhesive layer (that is, after the color-developing compound develops color by reaction with an acid derived from an acid generator). do. Deterioration of the discolored portion (bleeding, color fading, non-uniformity of color, etc.) is suppressed by suppressing the diffusion of the color-developing compound that has developed color.

1 is a cross-sectional schematic view of an embodiment of a variable color pressure-sensitive adhesive sheet of the present invention.
Fig. 2 is a schematic cross-sectional view of a modified example of the variable-color PSA sheet of the present invention (where the variable-color PSA sheet is a single-sided PSA sheet with a base material).
3 shows an example of a method of using the variable color pressure-sensitive adhesive sheet of the present invention. Fig. 3A shows a step of preparing a variable color PSA sheet and a member (adhered body), and Fig. 3B shows a step of bonding the members to each other via the variable color PSA sheet. Fig. 3C shows a step of curing the pressure-sensitive adhesive layer of the variable-color pressure-sensitive adhesive sheet as necessary, and Fig. 3D shows a step of forming a color-changing portion in the pressure-sensitive adhesive layer of the variable-color pressure-sensitive adhesive sheet.

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

The pressure-sensitive adhesive layer 10 is a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition and having transparency (visible light transmission). The adhesive composition is any one of the following 1st to 6th adhesive composition.

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.

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

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

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

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

The base polymer in the first adhesive composition exhibits rubber elasticity in the room temperature region. 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 adhesiveness of the pressure-sensitive adhesive layer 10, an acrylic polymer is preferably used as the base polymer.

The content 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, from the viewpoint of appropriately expressing the function of the base polymer in the pressure-sensitive adhesive layer 10. More preferably, it is 70 mass % or more.

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

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

As an alkyl (meth)acrylate, the (meth)acrylic acid alkylester which has a linear or branched C1-C20 alkyl group is mentioned, for example. Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylate. ) Isobutyl acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, (meth) Heptyl acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, (meth)acrylic acid Isodecyl, (meth)acrylate undecyl, (meth)acrylate dodecyl, (meth)acrylate isotridecyl, (meth)acrylate tetradecyl, (meth)acrylate isotetradecyl, (meth)acrylate pentadecyl, (meth)acrylate hexadecyl acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. As the (meth)acrylic acid alkyl ester, preferably, an alkyl acrylate ester having an alkyl group of 1 to 12 carbon atoms is used, more preferably, methyl acrylate and an alkyl acrylate ester having an alkyl group of 2 to 12 carbon atoms are used together , More preferably, methyl acrylate and 2-ethylhexyl acrylate are used together.

As (meth)acrylic acid alkoxyalkyl ester, the (meth)acrylic acid alkoxyalkyl ester which has a C1-C4 alkoxy group and a C1-C4 alkylene group is mentioned, for example. Examples of such (meth)acrylic acid alkoxyalkyl esters include 2-methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, and (meth)acrylic acid. 2-ethoxyethyl, 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, 2-ethoxymethyl (meth)acrylate is preferably used, and 2-ethoxymethyl acrylate is more preferably used.

(meth)acrylic acid ester may be used independently, and 2 or more types may be used together.

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

The first monomer component may also contain a copolymerizable monomer copolymerizable with (meth)acrylic acid ester. As a copolymerizable monomer, the monomer which has a polar group is mentioned, for example. 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 crosslinking point into the acrylic polymer and securing cohesive force of the acrylic polymer.

The copolymerizable monomer preferably includes 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 includes 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, ( 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of the hydroxyl group-containing monomer include preferably 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, more preferably 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. can be heard

The ratio of the hydroxyl group-containing monomer in the first monomer component is preferably 1% by mass or more, more preferably 1% by mass or more, from the viewpoint of introduction of a crosslinked structure into the acrylic polymer and securing of cohesive force in the pressure-sensitive adhesive layer 10. is 3% by mass or more, more preferably 5% by mass or more. The ratio is preferably from the viewpoint of adjusting the viscosity of the polymerization reaction solution during polymerization of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to 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, and N- Vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylphy Peridine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine- 2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. As a monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone is preferably used.

The ratio of the monomer having a nitrogen atom-containing ring in the first monomer component is a factor in securing cohesive force in the pressure-sensitive adhesive layer 10 and securing adhesion to an adherend in the pressure-sensitive adhesive layer 10. From the viewpoint, it is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more. The 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 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 carboxyl 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 carboxyl group-containing monomer in the first monomer component is determined by introducing a crosslinked structure into the acrylic polymer, securing cohesive force in the pressure-sensitive adhesive layer 10, and securing adherence to the adherend in the pressure-sensitive adhesive layer 10. From the viewpoint of, it is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more. The 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, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, amide group-containing monomers, monomers having a succinimide skeleton, maleimides, itaconimides, vinyl esters, vinyl ethers, and aromatic vinyl compounds.

As an acid anhydride monomer, maleic acid anhydride and itaconic acid anhydride are mentioned, for example.

Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, and sulfonic acid. propyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

As a phosphoric acid group containing monomer, 2-hydroxyethyl acryloyl phosphate is mentioned, for example.

As the epoxy group-containing monomer, for example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl (meth)acrylate, allyl glycidyl ether, and glycidyl (meth)acrylate ether.

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. , N-hydroxyalkyl (meth)acrylamide, N-alkoxyalkyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, and N-(meth)acryloylmorpholine. . Examples of N,N-dialkyl (meth)acrylamide include N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and N,N-dipropyl (meth)acrylamide. acrylamide, N,N-diisopropyl (meth)acrylamide, N,N-di(n-butyl) (meth)acrylamide, and N,N-di(t-butyl) (meth)acrylamide. can Examples of N-alkyl (meth)acrylamides include N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, and N-n-butyl (meth)acrylamide. amides. As N-hydroxyalkyl (meth)acrylamide, for example, N-(2-hydroxyethyl) (meth)acrylamide, N-(2-hydroxypropyl) (meth)acrylamide, N-(1 -Hydroxypropyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(2-hydroxybutyl) (meth)acrylamide, N-(3-hydroxybutyl) (meth)acrylamide, and N-(4-hydroxybutyl) (meth)acrylamide. Examples of N-alkoxyalkyl (meth)acrylamide include N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide. can

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

As maleimides, N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, and N-phenyl maleimide are mentioned, for example.

Examples of itaconimides include N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, and N-2-ethylhexyl itaconimide. imide, N-cyclohexylitaconimide, and N-laurylitaconimide.

Examples of vinyl esters include vinyl acetate and vinyl propionate.

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

As an aromatic vinyl compound, styrene, (alpha)-methylstyrene, and vinyltoluene are mentioned, for example. As olefins, ethylene, butadiene, isoprene, and isobutylene are mentioned, for example.

A copolymerizable monomer may be used independently and two or more types may be used together.

An 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, preferably solution polymerization. In solution polymerization, for example, after blending the first monomer component and the polymerization initiator in a solvent to prepare a reaction solution, the reaction solution is heated. Then, an acrylic polymer solution containing an acrylic polymer can be obtained by subjecting the first monomer component to a polymerization reaction in the reaction solution. As a polymerization initiator, a thermal polymerization initiator is used, for example. The usage amount of the polymerization initiator is, for example, 0.05 part 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.

As a thermal polymerization initiator, an azo polymerization initiator and a peroxide polymerization initiator are mentioned, for example. 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-cyanovalerian acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2' -azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, and 2,2 '-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride. As a peroxide polymerization initiator, dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxide are mentioned, for example.

The weight average molecular weight of the acrylic polymer is preferably 100000 or more, more preferably 300000 or more, still more preferably 500000 or more, from the viewpoint of securing the cohesive force in the pressure-sensitive adhesive layer 10. The same weight average molecular weight is preferably 5000000 or less, more preferably 3000000 or less, still more preferably 2000000 or less. The weight average molecular weight of the acrylic polymer is measured by a gel permeation chromatograph (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 copper glass transition temperature is, for example, -80°C or higher.

Regarding the glass transition temperature (Tg) of the polymer, a glass transition temperature (theoretical value) obtained based on the following formula of Fox can be used. Fox's formula is a relational expression between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of a homopolymer of monomers constituting the polymer. In Fox's formula below, Tg represents the glass transition temperature (°C) of a polymer, Wi represents the weight fraction of monomer i constituting the polymer, and Tgi represents the glass transition temperature of a homopolymer formed from monomer i. (°C) is shown. For the glass transition temperature of the homopolymer, literature values can be used, for example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Library 7 Synthesis for Paints" Introduction to resins” (Kyojo Kitaoka, Polymer Publishing Society, 1995) lists the glass transition temperatures of various homopolymers. On the other hand, about the glass transition temperature of the homopolymer of a monomer, it is also possible to obtain|require by the method specifically described in Unexamined-Japanese-Patent No. 2007-51271.

Fox's equation 1/(273+Tg)=Σ[Wi/(273+Tgi)]

The first adhesive composition may contain a crosslinking agent from the viewpoint of introducing a crosslinked structure into the base polymer. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. A crosslinking agent may be used independently and two or more types may be used together.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate. nate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthaline diisocyanate, triphenylmethane triisocyanate , and polymethylene polyphenyl isocyanate. Moreover, derivatives of these isocyanates are also mentioned as an isocyanate crosslinking agent. As the said isocyanate derivative, an isocyanurate modified body and a polyol modified body are mentioned, for example. As a commercially available isocyanate crosslinking agent, for example, Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), Coronate HL (of hexamethylene diisocyanate) Trimethylolpropane adduct, manufactured by Tosoh), Coronate HX (isocyanurate of hexamethylene diisocyanate, manufactured by Tosoh), and Takenate D110N (trimethyl of xylylene diisocyanate) All-propane adducts, manufactured by Mitsui Chemicals) are exemplified.

Examples of the epoxy crosslinking 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, trimethylolpropane triglycidyl ether, diglycidylaniline, diamineglycidylamine, N,N,N',N'-tetraglycidyl-m-xyl relendiamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

The blending amount of the crosslinking agent is, for example, 0.01 part by mass or more, preferably 0.05 part by mass or more, and more preferably 0.07 part by mass with respect to 100 parts by mass of the base polymer, from the viewpoint of securing the cohesive force of the pressure-sensitive adhesive layer 10. More than that. From the viewpoint of ensuring good tackiness in the pressure-sensitive adhesive layer 10, the compounding amount of the crosslinking agent relative 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. is less than

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

When a crosslinking catalyst is used, a crosslinking inhibitor that can be removed from the first adhesive composition post facto may be incorporated into the first adhesive composition. When dibutyltin dilaurate is used as a crosslinking catalyst, acetylacetone is preferably used as a crosslinking inhibitor. In this case, in the first adhesive composition, acetylacetone is coordinated with dibutyltin dilaurate, and the crosslinking reaction of the crosslinking agent with respect to the base polymer is suppressed. In the manufacturing process of the adhesive sheet S described later, after the adhesive composition is applied on the peeling film to form a coating film, acetylacetone can be volatilized and removed from the coating film by heating at a desired timing. Thereby, the crosslinking reaction of the crosslinking agent can be advanced.

The blending amount of the crosslinking inhibitor is, for example, 100 parts by mass or more, preferably 1000 parts by mass or more, based on 100 parts by mass of the crosslinking catalyst. The blending amount of copper is, for example, 5000 parts by mass or less.

As described above, the monomer component (second monomer component) blended together with the base polymer in the first adhesive composition includes an acid generator having a polymerizable functional group, and in the present embodiment, other monomer components having a polymerizable functional group A compound (another polymerizable compound) is further included. The polymerizable functional group has an ethylenically unsaturated double bond. As a polymerizable functional group, vinyl groups, such as a styrene group, a propenyl group, and a (meth)acryloyl group are mentioned, for example. A (meth)acryloyl group means an acryloyl group and/or a methacryloyl group. As a polymerizable functional group preferable from a reactive viewpoint, vinyl groups, such as a styrene group, and a (meth)acryloyl group are mentioned.

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

Examples of the first photoacid generator include an onium compound that generates an acid by ultraviolet irradiation and has a polymerizable functional group. The onium compound is provided in the form of, for example, an onium salt of an onium cation and an anion. As an onium cation, iodonium and sulfonium are mentioned, for example. Examples of the anion include sulfonic acid derivative anions, sulfonimide derivative anions, and sulfomethide derivative anions. Preferably, the anion has a polymerizable functional group. As the first photoacid generator, preferably, an onium salt of a sulfonic acid derivative anion having a polymerizable functional group and sulfonium is used, and more preferably, a sulfonic acid derivative anion having a (meth)acryloyl group and a sulfonium An onium salt of is used, more preferably triphenylsulfonium 4-vinylbenzene sulfonate. A method for synthesizing this photoacid generator is described, for example, in "Novel polymeric anionic photoacidgenerators (PAGs) and corresponding polymers for 193 nm lithography" (Journal of Materials Chemistry, 2006, Vol. 16, p 3701-3707). . 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, still 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, still more 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. More than that. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less.

Examples of the other polymerizable compound included 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). .

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, butoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, Stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Cyclopentenyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate Latex, 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 methacrylic acid phosphate, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, acryloylmo polyne, morpholinoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and N,N-dimethylaminoethyl (meth)acrylate. .

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

Examples of the difunctional monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. Methacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate ) acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, di(meth)acryloyl isocyanurate, and alkylene oxide-modified bisphenol di(meth)acrylate can be heard

As a trifunctional monomer, trimethylolpropane tri (meth)acrylate, pentaerythritol tri (meth)acrylate, and tris (acryloyloxyethyl) isocyanurate are mentioned, for example.

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

From the viewpoint of the rapid curing property of the pressure-sensitive adhesive layer 10, as the other polymerizable compound, preferably a polyfunctional monomer, more preferably a tetrafunctional or higher functional monomer, still more preferably dipentaerythritol hexa( meth)acrylates, particularly preferably dipentaerythritol hexaacrylate.

The blending amount of the second monomer component is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, 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. More preferably, it is 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 pressure-sensitive adhesive layer 10 after curing, the blending amount of the polymerizable compound relative 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 It is 40 parts by mass or less.

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

As 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, for example, leuco pigment, triarylmethane pigment, diphenylmethane pigment, fluorane pigments, spirophyran pigments, and rhodamine pigments. A color developing compound may be used independently, and 2 or more types may be used together.

Examples of the leuco dye include 2'-anilino-6'-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalide-3,9'-[9H]xanthene]; 3-Dibutylamino-6-methyl-7-anilinofluoran, 3-dipropylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran , 3-dimethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, and 3-(4-diethylamino-2-ethoxyphenyl )-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide.

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 fluoran dye include 3-diethylamino-6-methyl-7-chlorofluorane.As the spiropyran dye, Examples of the rhodamine pigment include 3-methylspirodinaphthopyran, and rhodamine-B-anilinolactam.

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 compounding 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, 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 1st adhesive composition may contain other components as needed. Examples of other components include silane coupling agents, tackifiers, plasticizers, softeners, antioxidants, surfactants, and antistatic agents.

The second adhesive composition has the same configuration as the above-described configuration of the first adhesive composition except for the following. In the second adhesive composition, the second monomer component contains a color-developing compound (second color-developing compound) that has a polymerizable functional group and develops color by reaction with an acid instead of the first acid generator having a polymerizable functional group. The second adhesive 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.

As the second color-developing compound (having a polymerizable functional group), for example, 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 A fluoran dye having a polymerizable functional 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. As a polymerizable functional group, a vinyl group, a propenyl group, and a (meth)acryloyl group are mentioned, for example. A (meth)acryloyl group means an acryloyl group and/or a methacryloyl group. From the viewpoint of reactivity, a compound having a (meth)acryloyl group as a polymerizable functional group is preferably used 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, preferably, a leuco dye having a polymerizable functional group is used, more preferably a leuco dye having a (meth)acryloyl group is used, and still more preferably a leuco dye having an acryloyl group is used Examples of the leuco dye having a polymerizable functional group include the acryloyl group-containing leuco dye described in International Publication No. 2013/048993.

As the second acid generator (not having a polymerizable functional group), a photoacid generator (second photoacid generator not having a polymerizable functional group) that generates an acid when irradiated with active energy rays is preferably used. . As the second photo-acid generator, for example, an onium compound that generates an acid by irradiation with ultraviolet light is exemplified. The onium compound is provided in the form of, for example, an onium salt of an onium cation and an anion. As an onium cation, iodonium and sulfonium are mentioned, for example. 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 2nd photo-acid generator may be used independently, and 2 or more types may be used together. The second adhesive composition preferably contains an onium salt (onium compound) composed of sulfonium and C ₄ F ₉ HSO ₃ ^- as the second photo-acid generator.

In the second adhesive composition, the blending amount of the second acid generator relative 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. More than that. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, still more 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; Especially preferably, it is 6 mass parts or more. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less.

The 3rd adhesive composition has the same structure as the above-mentioned structure with respect to the 1st adhesive composition except the following. In the third adhesive composition, the second monomer component further contains a second color-developing compound that has a polymerizable functional group and develops color by reaction with an acid. The third adhesive composition, in the present embodiment, 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 compounds described above as the second color-developing compound in the second adhesive composition.

In the third adhesive composition, the compounding 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. More than that. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, still more preferably 500 parts by mass or less.

The 4th adhesive composition has the same structure as the above-mentioned structure with respect to the 1st adhesive composition except the following. In the fourth adhesive composition, the monomer component (first monomer component) forming the base polymer contains an acid generator having a polymerizable functional group (first acid generator). The fourth adhesive composition does not substantially contain the second monomer component in the present embodiment.

Examples of the first acid generator in the fourth adhesive composition include the compounds described above as the first acid generator in the first adhesive 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. More than that. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, still more preferably 500 parts by mass or less.

The compounding 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, particularly preferably It 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, still more preferably 12 parts by mass or less.

The fifth adhesive composition has the same configuration as the above-described configuration of 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 having a polymerizable functional group (second color-developing compound). The fifth adhesive 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 adhesive 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 compounds described above as the second color-developing compound in the second adhesive composition. Examples of the second acid generator in the fifth adhesive composition include the compounds described above as the second acid generator in the second adhesive composition.

In the fifth adhesive composition, the blending amount of the second acid generator (with no polymerizable functional group) relative 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. , 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, still more preferably 500 parts by mass or less.

In the fifth 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; Especially preferably, it is 6 mass parts or more. The blending amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less.

The 6th adhesive composition has the same structure as the above-mentioned structure with respect to the 1st adhesive composition except the following. In the sixth adhesive composition, the monomer component (first monomer component) forming the base polymer is an acid generator having a polymerizable functional group (first acid generator) and a color-developing compound having a polymerizable functional group (second color-developing compound). ). In the present embodiment, the sixth adhesive 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 adhesive composition include the compounds described above as the first acid generator in the first adhesive composition. Examples of the second color-developing compound in the sixth adhesive composition include the compounds described above 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. More than that. The blending amount is preferably 1000 parts by mass or less, more preferably 700 parts by mass or less, still more preferably 500 parts by mass or less.

The compounding 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, particularly preferably It 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, still more preferably 12 parts by mass or less.

The adhesive sheet S is formed by applying, for example, the first, second, third, fourth, fifth, or sixth adhesive composition described above on a release film (first release film) to form a coating film. , It can manufacture by drying the said coating film (in FIG. 1, the adhesive sheet S is arrange|positioned on the peeling film L shown by the virtual line).

As a peeling film, the plastic film which has flexibility is mentioned, for example. As the said plastic film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, and a polyester film are mentioned, for example. The thickness of the peeling film is, for example, 3 μm or more, and is, for example, 200 μm or less. The surface of the release film is preferably subjected to release treatment.

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

When the adhesive composition contains a crosslinking agent, a crosslinking reaction proceeds simultaneously with the drying described above or by aging thereafter. Aging conditions are appropriately set depending on the type of crosslinking agent. The aging temperature is, for example, 20°C to 160°C. The aging time is, for example, 1 minute to 7 days.

Moreover, you may laminate|stack a peeling film (2nd peeling film) further on the adhesive layer 10 on the 1st peeling film before or after aging. The second release film is a flexible plastic film subjected to surface release treatment, and the same one as described above for the first release film can be used.

As described above, the adhesive sheet S in which the adhesive face is covered and protected by the release film can be manufactured. Each peeling film is peeled off from the adhesive sheet S as needed when using the 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 standpoint of the handleability of the PSA sheet S, the thickness of the PSA layer 10 is preferably 300 μm or less, more preferably 200 μm or less, even 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 still more preferably 1% or less. Such a structure is suitable for inspecting the presence or absence of foreign matter and air bubbles between the adhesive sheet S and the adherend after bonding the adhesive sheet S to the adherend. The haze of the adhesive layer 10 can be measured using a haze meter based on JIS K7136 (2000). As a haze meter, "NDH2000" by Nippon Denshoku Kogyo Co., Ltd. and "HM-150 type|mold" by Murakami Color Technology Laboratory Co., Ltd. are mentioned, for example.

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

After the pressure-sensitive adhesive sheet S is bonded to the glass plate, the adhesive strength to the stainless plate in a peeling test under peeling conditions of 23°C, a peeling angle of 180°, and a peeling speed of 300 mm/min is, for example, 1 N/min. It is 25 mm or more and, for example, 50 N/25 mm or less.

When the pressure-sensitive adhesive layer 10 is formed of 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 composed of a photoacid generator. The wavelength region in which the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X is 2 or more is within the range 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 PSA sheet S may be a single-sided PSA sheet with a base material including a base material 20 in addition to the PSA layer 10 . In this case, the pressure-sensitive adhesive sheet S specifically includes the pressure-sensitive adhesive layer 10 and the base material 20 disposed on one side in the thickness direction. Preferably, the substrate 20 contacts one side of the pressure-sensitive adhesive layer 10 in the thickness direction.

The substrate 20 is an element that functions as a transparent support. The substrate 20 is, for example, a plastic film having flexibility. 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 ethylene. • Ethyl acrylate copolymer, and ethylene/vinyl alcohol copolymer. As polyester, polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate are mentioned, for example. Examples of the polyamide include polyamide 6, polyamide 6 and 6, and partially aromatic polyamide. In the base material 20, from the viewpoint of achieving both transparency and mechanical strength, the plastic material of the base material 20 is preferably polyester, more preferably polyethylene terephthalate.

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

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

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

The PSA sheet S shown in FIG. 2 can be manufactured, for example, by the same method as the PSA sheet manufacturing method described above, except that the substrate 20 is used instead of the first peeling film.

3A to 3D show an example of a method of using the pressure-sensitive adhesive sheet S. This method includes a preparation process, a bonding process, and a discoloration part formation process.

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 substrate. As a transparent substrate, a transparent plastic substrate and a transparent glass substrate are mentioned.

Next, in the joining step, as shown in Fig. 3B, the first member 31 and the second member 32 are joined with the adhesive sheet S interposed therebetween. In this way, the layered product Z is obtained. In the layered body Z, the adhesive sheet S is disposed so as to contact one surface of the first member 31 in the thickness direction, and the second member 32 is disposed on one side of the adhesive sheet S in the thickness direction. It is placed so as to contact the surface.

After the bonding step, the presence or absence of foreign substances and air bubbles between the members 31 and 32 and the adhesive sheet S is inspected as necessary.

In the PSA sheet S provided with the PSA layer 10 formed of the first, second or third PSA composition, the PSA layer 10 is then cured (curing step) as shown in FIG. 3C. . Specifically, active energy rays are applied to the pressure-sensitive adhesive layer 10 in the layered product Z (when the above inspection is performed, the layered product Z that has passed the inspection) is irradiated with a polymerization reaction of the second monomer component. advance

The active energy rays in this step are irradiated to the pressure-sensitive adhesive layer 10 from the side of the transparent second member 32 . As a light source for active energy ray irradiation in this process, an ultraviolet LED lamp (UV-LED lamp), a black light, a high-pressure mercury lamp, and a metal halide lamp are mentioned, for example. In the active 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 necessary.

The active energy ray (first active energy ray) has a different wavelength range from the above-described active energy ray (second active energy ray) for generating acid from the acid generator. In the present embodiment, the first active energy ray has a wavelength that does not substantially generate 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, even more preferably 380 nm, still more preferably 385 nm, still more preferably 390 nm, particularly preferably is 395 nm. In the present embodiment, preferably, a photopolymerization initiator that initiates a polymerization reaction of the second monomer component by receiving active energy ray irradiation of such a wavelength is incorporated into the pressure-sensitive adhesive layer 10 .

In this step, in the pressure-sensitive adhesive layer 10 that has been 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 modulus of elasticity of the pressure-sensitive adhesive layer 10 increases.

As described above, the pressure-sensitive adhesive layer 10 preferably has a wavelength range (wavelength range 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 a wavelength range of 300 nm or more and 500 nm or less. do. The ratio (Y/X) in the wavelength range R is preferably 3 or more, more preferably 10 or more, still more preferably 100 or more. Preferably, at least a part of the wavelength of the irradiated first active energy ray is within the wavelength range R. More preferably, all of the wavelengths of the first active energy ray to be irradiated are within the wavelength range R. The configuration of irradiating the pressure-sensitive adhesive layer 10 with the first active energy ray having a wavelength within such a wavelength range is to cure the pressure-sensitive adhesive layer 10 while suppressing discoloration in the pressure-sensitive adhesive layer 10 in the curing step. Suitable. In the curing step, from the viewpoint of curing the pressure-sensitive adhesive layer 10 while suppressing discoloration in the pressure-sensitive adhesive layer 10, the ratio of the absorbance Y of the photopolymerization initiator to the absorbance X of the photoacid generator is preferably larger. .

Next, in the discoloration portion forming step, as shown in Fig. 3D, the discoloration scheduled location in the adhesive layer 10 of the layered product Z is irradiated with a second active energy ray, and the adhesive layer 10 is discolored. Form part (11). Specifically, through a mask pattern (not shown) for masking a predetermined area in the pressure-sensitive adhesive layer 10 from the side of the transparent second member 32, the second active energy ray is transmitted to the pressure-sensitive adhesive layer 10. investigate As a result, the portion of the pressure-sensitive adhesive layer 10 not masked by the mask pattern is discolored.

Examples of the light source for the second active energy ray irradiation include an ultraviolet LED lamp (UV-LED lamp), a black light, a high-pressure mercury lamp, and a metal halide lamp. In addition, 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 as necessary.

The second active energy ray has a different wavelength range from the first active energy ray described above. The wavelength range of the second active energy ray preferably includes at least a smaller range (wavelength range on the shorter wavelength side) than the wavelength range of the first active energy ray (the wavelength range of the second active energy ray is equal to the wavelength of the first active energy ray). ranges and overlapping ranges). When the second active energy ray has a lower limit in the wavelength range, or when a lower limit is provided in the wavelength range of the second active energy ray, for example, using a wavelength cut filter, the lower limit of the wavelength range of the second active energy ray is, It is preferably 300 nm, more preferably 305 nm, even more preferably 310 nm, even more preferably 315 nm, still more preferably 320 nm, still more preferably 325 nm, and particularly preferably 330 nm. Alternatively, light with a wavelength of less than 300 nm may be contained in the second active energy ray. As a light source of such light, a high pressure mercury lamp and a metal halide lamp are mentioned, for example. When the second active energy ray has an upper limit in the wavelength range, or when an upper limit is provided in the wavelength range of the second active energy ray, for example, using 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, even 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 an active energy ray of such a wavelength is blended into the pressure-sensitive adhesive layer 10 .

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

For example, as described above, the adhesive sheet S can be used for bonding between members. When the first member 31 is a display panel such as an organic EL panel, by providing the discoloration 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 the said metal wiring can be suppressed.

In the pressure-sensitive adhesive sheet S, the pressure-sensitive adhesive layer 10 (the pressure-sensitive adhesive layer formed of the first, second, third, fourth, fifth, or sixth pressure-sensitive adhesive composition described above) has color developing properties by reaction with an acid. The compound and the acid generator are contained in the above-described specific aspect. Therefore, after bonding the PSA sheet S to the adherend, in the area where the color change is expected to occur in the PSA layer 10 (at least a part of the PSA layer 10), acid is generated by application of an external stimulus to the area in question. An acid can be generated from the agent, and the color-developing compound can be developed by the acid. According to such an adhesive sheet S, the presence or absence of foreign matter and air bubbles between the sheet and the adherend can be inspected after bonding and before formation of the discolored portion of the adhesive layer 10.

In the pressure-sensitive adhesive layer 10 of the pressure-sensitive adhesive sheet S, at least one of a color-developing compound that develops color by reaction with acid and an acid generator is incorporated into the base polymer or in a copolymerizable state as the second monomer component. (In the case of taking the latter state, at least one of the color developing compound and the acid generator can be incorporated into the polymer network by undergoing a polymerization reaction of the second monomer component in the pressure-sensitive adhesive layer 10.) . Such a pressure-sensitive adhesive sheet S prevents the color-developing compound from spreading after the color-changing portion is formed on the pressure-sensitive adhesive layer 10 (that is, after the color-developing compound develops color by reaction with an acid derived from the acid generator). suitable for suppression Deterioration of the discolored portion (bleeding, color fading, non-uniformity of color, etc.) is suppressed by suppressing the diffusion of the color-developing compound that has developed color.

As described above, the pressure-sensitive adhesive sheet S is capable of discoloring at least a part of the pressure-sensitive adhesive layer 10 after bonding to an adherend, and is suitable for suppressing deterioration of the discolored portion of the pressure-sensitive adhesive layer 10. Suppression of deterioration of the discolored portion in the pressure-sensitive adhesive layer 10 is useful for maintenance of functional characteristics of the discolored portion, such as design, shielding, and antireflection.

In the above-mentioned embodiment, the 4th, 5th, and 6th adhesive composition are the other polymeric compounds (monofunctional monomer, polyfunctional monomer, etc. ) may be contained together with, for example, a photopolymerization initiator. In addition, the said 4th, 5th, and 6th adhesive composition may respectively contain the said 1st acid generator and/or the 2nd color developing compound as a 2nd monomer component.

According to the pressure-sensitive adhesive sheet S having the pressure-sensitive adhesive layer 10 formed of the fourth, fifth or sixth pressure-sensitive adhesive composition, the curing step described above with reference to FIG. 3C can be performed. Specifically, the elastic modulus of the pressure-sensitive adhesive layer 10 can be increased by irradiating the pressure-sensitive adhesive layer 10 in the layered product Z with active energy rays to advance the polymerization reaction of the second monomer component.

Further, the first and fourth adhesive compositions may each contain the aforementioned second acid generator. The second and fifth adhesive compositions may each contain the first color-developing compound described above. The third and sixth adhesive compositions may contain a second acid generator and a first color developing compound, respectively.

Example

The present invention will be described in detail by showing examples below, but the present invention is not limited to the examples. In addition, the specific numerical values such as the compounding amount (content), physical property values, and parameters described below are the compounding amounts (content), physical property values, and parameters corresponding to them described in the above-mentioned “Specific Content for Carrying Out the Invention”. It can be substituted with the upper limit (numerical value defined as "below" or "less than") or the lower limit (numerical value defined as "greater than" or "exceeding") of the same.

[Example 1]

<Preparation of base polymer>

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet pipe, 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of methyl methacrylate (MMA), and 2-hydroxy acrylate 13 parts by mass of ethyl (HEA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 0.2 part by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and a solvent A mixture containing 233 parts by mass of ethyl acetate as the mixture was stirred at 60°C for 7 hours in a nitrogen atmosphere (polymerization reaction). Thus, a polymer solution (polymer solution P ₁ ) containing an acrylic polymer was obtained. The weight average molecular weight (Mw) of the acrylic polymer in this polymer fluid _P1 was 1,200,000.

<Preparation of adhesive composition>

To the polymer solution P ₁ containing the acrylic polymer, per 100 parts by mass of the acrylic polymer (base polymer), an isocyanate crosslinking agent as a crosslinking agent (trade name “Takenate D110N”, trimethylolpropane of xylylene diisocyanate) 75% ethyl acetate solution of duct body, manufactured by Mitsui Chemicals) 0.25 parts by mass (solid content equivalent) and dibutyltin dilaurate (trade name "OL-1", 1 mass% ethyl acetate solution, Tokyo Pine) as a crosslinking catalyst Chemical Co., Ltd.) 0.01 parts by mass (in terms of solid content), 3 parts by mass of acetylacetone as a crosslinking inhibitor (ligand for crosslinking catalyst), and a leuco dye (trade name "S-205", 2'-anilino- 2 parts by mass of 6'-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalide-3,9'-[9H]xanthene], manufactured by Yamada Chemical Industry Co., Ltd., and a copolymerizable monomer component (Second monomer component) 30.75 parts by mass and 0.38 parts by mass of a photopolymerization initiator (trade name "Omnirad 819", bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins BV) were added and mixed to achieve adhesiveness. composition was prepared. The second monomer component is 22.5 parts by mass of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a monofunctional monomer and dipentaerythritol hexaacrylate (as a polyfunctional monomer) per 100 parts by mass of the acrylic polymer (base polymer). manufactured by Daicell Allnex Co., Ltd.) 2 parts by mass and 6.25 parts by mass of triphenylsulfonium 4-vinylbenzene sulfonate as a photoacid generator having a polymerizable functional group.

<Formation of pressure-sensitive adhesive layer>

On a polyethylene terephthalate film (base film) having a thickness of 38 μm, the surface of which was subjected to release treatment, the adhesive composition was applied with a fountain roll to form a coating film. Next, this coating film was dried by heating at 132°C for 3 minutes. In this way, an adhesive layer having a thickness of 25 μm was formed on the base film. Next, the release-treated surface of the separator (a polyethylene terephthalate film having a thickness of 38 µm and subjected to release treatment on one side) was bonded to the pressure-sensitive adhesive layer on the base film. Thereafter, aging treatment was performed at 60°C for 24 hours to promote crosslinking reaction in the pressure-sensitive adhesive layer. In the above manner, the pressure-sensitive adhesive sheet of Example 1 was produced.

[Example 2]

<Synthesis of Leuco Dye Containing Polymerizable Functional Group>

First, in the flask, 5.5 mL of 3-methyl-4-aminophenol methyl ether was added dropwise to 40 g of concentrated sulfuric acid (97%) while stirring the concentrated sulfuric acid, 1 µL at a time. Next, to the obtained mixture, 16.4 g of 2-(2-hydroxy-4-dimethylamino)benzoylbenzoic acid was added. Next, the obtained mixture was stirred at 35°C for 72 hours. Next, the mixture was gradually added into a 1 L flask containing 320 g of ice. Next, 290 g of 11% sodium hydroxide solution was added into the flask. Next, the obtained mixture was stirred at 96°C for 4 hours. Next, after adding 80 mL of toluene to the mixture, the mixture was stirred at 96°C for 2 hours. Next, after this reaction solution was allowed to stand for 30 minutes, the organic layer formed as the upper layer of the reaction solution was collected in a flask using a pipette. Next, the contents of the flask were cooled in a 3.5°C water bath for 30 minutes. Next, the contents were filtered with a filter paper (2.5 µm eye size), and then washed with 5 mL of toluene. Next, the filtrate was dried at 65°C for 4 hours in a vacuum to obtain 5.2 g of compound P ₁ represented by the following formula (1). Next, 2.4 g of Compound P ₁ was put into the flask, along with 30 mL of tetrahydrofuran, 2 mL of dimethylformamide, and 2 mL of triethylamine. Next, after gradually adding 0.64 mL of acryloyl chloride to the mixture in the flask, the mixture was stirred at room temperature for 24 hours. Next, the obtained mixture was poured into 20 mL of ion-exchanged water. Next, the resulting precipitate was filtered with a filter paper (2.5 µm eye size). Next, the solid material (filtrate) 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 formula (2).

[Formula 1]

[Formula 2]

<Preparation of base polymer>

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, 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 - 15 parts by mass of pyrrolidone (NVP), 2 parts by mass of the leuco dye (compound P ₂ ) having a polymerizable functional group, and 0.2 mass parts of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator part, and a mixture containing 210 parts by mass of ethyl acetate as a solvent was stirred at 60°C for 7 hours in a nitrogen atmosphere (polymerization reaction). In this way, a polymer solution (polymer solution P ₂ ) containing an acrylic polymer was obtained. The weight average molecular weight (Mw) of the acrylic polymer in this polymer fluid _P2 was 240,000.

<Preparation of adhesive composition>

In the polymer solution P ₂ containing the acrylic polymer, 0.25 parts by mass (in terms of solid content) of an isocyanate crosslinking agent (trade name “Takenate D110N”, manufactured by Mitsui Chemicals) as a crosslinking agent per 100 parts by mass of the acrylic polymer (base polymer); Dibutyltin dilaurate (trade name "OL-1", manufactured by Tokyo Fine Chemical Co., Ltd.) as a crosslinking catalyst 0.01 parts by mass (in terms of solid content), 3 parts by mass of acetylacetone as a crosslinking inhibitor, and a photoacid generator (trade name " CPI-310B”, sulfonium and (C ₆ F ₅ ) ₄ B ^- onium salt, manufactured by San-Apro Co., Ltd.) were added and mixed with 7 parts by mass to prepare an adhesive composition.

<Formation of pressure-sensitive adhesive layer>

On a polyethylene terephthalate film (base film) having a thickness of 38 μm, the surface of which was subjected to release treatment, the adhesive composition was applied with a fountain roll to form a coating film. Next, this coating film was dried by heating at 132°C for 3 minutes. In this way, an adhesive layer having a thickness of 25 μm was formed on the base film. Next, the release-treated surface of the separator (a polyethylene terephthalate film having a thickness of 38 µm and subjected to release treatment on one side) was bonded to the pressure-sensitive adhesive layer on the base film. Thereafter, aging treatment was performed at 60°C for 24 hours to promote crosslinking reaction in the pressure-sensitive adhesive layer. In the above manner, the PSA sheet of Example 2 was produced.

[Comparative Example 1]

A PSA sheet of Comparative Example 1 was produced in the same manner as the PSA sheet of Example 1 except for the following.

Diphenyl-2,4,6-trimethylphenylsulfonium p-toluene sulfonate as a photoacid generator not having a polymerizable functional group in place of 6.25 parts by mass of the photoacid generator containing a polymerizable functional group in the preparation of the adhesive composition (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 6.25 parts by mass was used.

<Durability test>

With respect to the pressure-sensitive adhesive layer of each pressure-sensitive adhesive sheet in Examples 1 and 2 and Comparative Example 1, the degree of blurring suppression of the formed discolored portion was investigated as follows.

First, a plurality of PSA sheets were prepared for each PSA sheet in Examples 1 and 2 and Comparative Example 1.

Next, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was irradiated with ultraviolet light in an environment at 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 ultraviolet light irradiation). In this ultraviolet irradiation, a UV-LED lamp with a wavelength of 405 nm in a UV-LED irradiation device manufactured by Quark Technologies (model number "QEL-350-RU6W-CW-MY") was used as a light source, and the pressure-sensitive adhesive layer was applied over the base film. Ultraviolet rays were irradiated, and the integrated irradiation light amount was 2000 mJ/cm ² (the integrated irradiation light amount in a wavelength range of 395 to 445 nm).

Next, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was irradiated with ultraviolet light through a photomask having linear openings to form linear discolored portions in the pressure-sensitive adhesive layer. The photomask is formed of a dry film photoresist disposed on the surface of the 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 differs for each photomask). In the ultraviolet irradiation, a UV-LED lamp with a wavelength of 365 nm in a UV-LED irradiation device manufactured by Quark Technology (model number "QEL-350-RU6W-CW-MY") was used as a light source, and an adhesive was applied over a photomask and base film. The layer was irradiated with ultraviolet rays, and the cumulative amount of irradiation light was 2000 mJ/cm ² (the integrated amount of irradiation light in the range of wavelength 320 to 390 nm).

Next, the line width of the linear discoloration portion formed on the pressure-sensitive adhesive layer was measured (measurement of initial line width). Specifically, first, the linear discoloration portion formed on the pressure-sensitive adhesive layer was observed with a digital microscope (trade name "VHX-900", manufactured by KEYENCE), and the area including a part of the discoloration portion and its vicinity was magnified 50 times. was filmed with 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 discoloration portion was measured.

Next, the pressure-sensitive adhesive sheet in which linear discoloration portions were formed in the pressure-sensitive adhesive layer was subjected to heat treatment 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. A specific measurement method is the same as the measurement method described above regarding the measurement of the initial line width. Table 1 shows the line width W1 of the linear discoloration portion before the durability test, the line width W2 of the linear discoloration portion after the durability test, and the increase rate (W2/W1) of the line width W2 relative to the line width W1.

The rate of increase in line width (W2/W1) of the linear discoloration portion after the durability test was smaller in each of the PSA sheets of Examples 1 and 2 than that of the PSA sheet of Comparative Example 1. That is, in each of the PSA sheets of Examples 1 and 2, the bleeding of the discolored portion of the PSA layer was suppressed more than that of the PSA sheet in Comparative Example 1.

The embodiment described above is an illustration of the present invention, and the present invention should not be interpreted limitedly by the embodiment. Modifications of the present invention obvious to those skilled in the art in the art are included in the scope of the later claims.

The variable-color adhesive sheet of the present invention is used, for example, in the manufacturing process of a display panel for bonding elements included in a laminated structure of a display panel.

S Adhesive Sheet (Variable Color Adhesive Sheet)
10 adhesive layer
11 discoloration part
20 entries
31 first member
32 Second member

Claims (5)

A pressure-sensitive adhesive layer containing a base polymer and a monomer component or a polymer of the monomer component as the 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 acid,
The monomer component contains a color-developing compound that has a polymerizable functional group and develops color by reaction with an acid, and the pressure-sensitive adhesive layer further contains an acid generator, or
The color-changing pressure-sensitive adhesive sheet, wherein the monomer component includes an acid generator having a polymerizable functional group and a color-developing compound having a polymerizable functional group and developing color by reaction with an acid. According to claim 1,
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. According to claim 1,
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,
A variable color pressure-sensitive adhesive sheet having a wavelength range 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 a wavelength range of 300 nm or more and 500 nm or less. According to claim 1,
The pressure-sensitive adhesive layer has a thickness of 10 μm or more and 300 μm or less. According to claim 1,
The variable color pressure-sensitive adhesive sheet further comprising a base material disposed on one side of the pressure-sensitive adhesive layer in the thickness direction.