TW202242050A - Pressure-sensitive adhesive sheet changeable in color - Google Patents

Abstract

A pressure-sensitive adhesive sheet (S) as this pressure-sensitive adhesive sheet changeable in color includes a pressure-sensitive adhesive layer (10). The pressure-sensitive adhesive layer (10) comprises: a polymer component having a microphase separation structure including a first phase and a second phase; and a colorant which can be colored by an external stimulus. The colorant is compatible with the first phase but incompatible with the second phase. The polymer component includes a polymer having, in the molecule, a first segment, which forms the first phase, and a second segment, which forms the second phase. The first segment has a first glass transition temperature of 10-120 DEG C, and the second segment has a second glass transition temperature, which is lower than the first glass transition temperature.

Description

Color changeable adhesive sheet

The invention relates to a color-changing adhesive sheet.

A display panel such as an organic EL panel (Electroluminescence, electroluminescence) has a laminated structure including a pixel panel, a cover member, and the like. In the manufacturing process of this kind of display panel, in order to bond the elements contained in the laminated structure to each other, for example, a transparent adhesive sheet can be used.

In addition, as a transparent adhesive sheet disposed on the light emitting side (image display side) of the pixel panel in the display panel, it is proposed to use a preformed adhesive sheet for imparting design, light-shielding, and anti-reflective properties to specific parts of the above-mentioned sheet. Adhesive sheet for colored parts. 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. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-203810

[Problem to be solved by the invention]

However, in the case of using an adhesive sheet on which a colored portion is formed in advance in the manufacturing process of a display panel, after the adhesive sheet is attached to an adherend, the relationship between the adherend and the adhesive sheet cannot be properly inspected. Check whether there are foreign matter and air bubbles between the colored parts. When the adhesive sheet is bonded in the display panel manufacturing process, it is necessary to be able to properly check whether there are foreign substances and air bubbles between the adherend and the adhesive sheet after the bonding.

On the other hand, from a viewpoint of ensuring the function of the colored part provided in the transparent adhesive sheet for display panels, it is necessary to suppress the deterioration of a colored part.

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

The present invention [1] includes a color-changing adhesive sheet, which is provided with a color-changing adhesive layer, and the adhesive layer includes: a polymer component that forms a microphase-separated structure including a first phase and a second phase; And a coloring agent, which can develop color by external stimulation; the coloring agent has compatibility with the first phase, and does not have compatibility with the second phase, and the polymer component includes a polymer, and the above-mentioned polymer is in the molecule It has a first segment that forms the first phase and a second segment that forms the second phase. The first segment has a first glass transition temperature of 10°C to 120°C, and the second segment has a temperature lower than that of the first The second glass transition temperature of the glass transition temperature.

The present invention [2] includes the color-variable adhesive sheet as described in the above [1], wherein the second glass transition temperature is 50° C. or lower.

The present invention [3] includes the color-variable adhesive sheet described in the above [1] or [2], wherein the difference between the first glass transition temperature and the second glass transition temperature is not less than 40°C and not more than 200°C.

The present invention [4] includes the color-changing adhesive sheet described in any one of the above-mentioned [1] to [3], wherein the polymer is a block polymer having the first segment as the first segment. 1 polymer block, and a 2nd polymer block as a 2nd segment.

The present invention [5] includes the color-changing adhesive sheet as described in any one of the above-mentioned [1] to [3], wherein the polymer is a graft polymer, and the graft polymer has a polymer as the second segment main chain, and the side chain of the polymer as the first segment.

The present invention [6] includes the color-variable adhesive sheet described in any one of the above-mentioned [1] to [5], wherein the mass ratio of the second phase in the polymer component is greater than that of the first phase.

The present invention [7] includes the color-variable adhesive sheet described in any one of the above-mentioned [1] to [6], wherein the colorant is a compound that develops color by reacting with an acid, and the adhesive layer further contains Photoacid generators.

The present invention [8] includes the color-variable adhesive sheet described in the above [7], wherein the photoacid generator has compatibility with the first phase and has no compatibility with the second phase.

The present invention [9] includes the color-changing adhesive sheet described in any one of the above-mentioned [1] to [8], wherein the adhesive layer is formed by linearly applying external stimuli to the adhesive layer. The first discoloration width W1 of the discoloration region, and the second discoloration width W2 of the discoloration region after heat-treating the adhesive layer at 85° C. for 120 hours satisfy 0.5≦W2/W1≦1.6.

The present invention [10] includes the color-changing adhesive sheet described in any one of the above-mentioned [1] to [9], wherein the adhesive layer is formed by linearly applying external stimuli to the adhesive layer. The first discoloration width W1 of the discoloration area, and the third discoloration width W3 of the discoloration area after heat-treating the adhesive layer at 65°C and 90% relative humidity for 120 hours satisfy 0.5≦W2/W1≦1.6. [Effect of Invention]

In the color-variable adhesive sheet of the present invention, as described above, the adhesive layer contains a coloring agent capable of developing color by external stimulation. Therefore, after attaching the color-changing adhesive sheet to the adherend, by applying an external stimulus to the portion of the adhesive layer to be discolored (at least a part of the adhesive layer), the portion can be partially discolored. In the case of such a color-changing adhesive sheet, it is possible to check whether there are foreign matter and air bubbles between the sheet and the adherend after lamination and before the discoloration of the adhesive layer is formed.

In addition, in the color-changing adhesive sheet, as described above, the adhesive layer includes a polymer component having a microphase-separated structure including a first phase and a second phase, and the coloring agent has a phase opposite to the first phase. Capacitive, and not compatible with the second phase. In addition, in the color-changing adhesive sheet, as described above, the polymer component includes a polymer having a first segment forming the first phase and a second segment forming the second phase in the molecule. The first segment has a first glass transition temperature of 10°C to 120°C, and the second segment has a second glass transition temperature lower than the first glass transition temperature. The color-changing adhesive sheet having such a configuration is suitable for suppressing movement (diffusion, etc.) of the developed colorant after the discolored portion is formed in the adhesive layer (ie, after the colorant is developed by external stimulation). By suppressing the movement of the colorant that has been developed, deterioration of the discolored portion (bleeding, fading, unevenness of the color tone, etc.) is suppressed.

As shown in FIG. 1 , the adhesive sheet S which is one embodiment of the color-changing adhesive sheet of the present invention includes an adhesive layer 10 . The adhesive sheet S has a sheet shape with a specific thickness, and extends in a direction (surface direction) perpendicular to the thickness direction. The adhesive sheet S can be used, for example, as a transparent adhesive sheet disposed on the image display side of a pixel panel in a display panel (having a laminated structure including a pixel panel, a cover member, etc.) such as an organic EL panel.

The adhesive layer 10 is a pressure-sensitive adhesive layer formed from an adhesive composition. The adhesive layer 10 has transparency (visible light transmittance). The adhesive layer 10 contains a polymer component and a coloring agent which can be colored by external stimulation described below. The portion of the adhesive layer 10 that receives external stimuli changes color. That is, the transparency of the portion of the pressure-sensitive adhesive layer 10 subjected to external stimuli can be lowered afterwards.

The polymer component is an adhesive component that exhibits adhesiveness in the adhesive layer 10 . The polymer composition exhibits rubber elasticity in the room temperature range. As polymer components, for example, acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and Fluoropolymers. From the viewpoint of securing good transparency and adhesiveness of the adhesive layer 10 , it is preferable to use an acrylic polymer as the polymer component.

The polymer component has a microphase-separated structure including a first phase and a second phase in the adhesive layer 10 . The first phase is a phase compatible with the colorant. The second phase is a phase incompatible with the colorant. As the microphase separation structure, for example, a spherical structure (sea-island structure) as shown in Figure 2A, a cylinder structure as shown in Figure 2B, a spiral structure (bicontinuous structure) as shown in Figure 2C, and Layered structure as shown in Figure 2D.

In the structure shown in Fig. 2A, the first phase M1 is a spherical dispersed phase, and the second phase M2 is a matrix. In the structure shown in Fig. 2B, the first phase M1 is a cylindrical dispersed phase, and the second phase M2 is a matrix. In the structure shown in Fig. 2C, the first phase M1 has a three-dimensional network structure, and the second phase M2 is a matrix. In the structure shown in FIG. 2D , the plate-shaped first phase M1 and the plate-shaped second phase M2 repeat alternately. From the viewpoint of inhibiting the migration of the colorant in the adhesive layer 10, the polymer component preferably has a microphase separation structure as shown in FIG. 2A, FIG. 2B or FIG. 2C.

The polymer component includes a polymer (first polymer) having a first segment forming a first phase and a second segment forming a second phase in a molecule. The first polymer may, for example, be a block polymer having a first polymer block as a first segment and a second polymer block as a second segment. A block polymer may have a plurality of first polymer blocks with different monomer compositions, and may also have a plurality of second polymer blocks with different monomer compositions (in this case, the block polymer is based on monomer A multi-block copolymer in which the number of block types in the composition is 3 or more). As the first polymer, a graft polymer having a polymer main chain as a second segment and a polymer side chain as a first segment may also be exemplified. The grafted polymer may have multiple polymer side chains with different monomer compositions, and may also have multiple polymer blocks with different monomer compositions within the polymer main chain. The polymer component may contain one kind of first polymer, or may contain plural kinds of first polymers. In addition, the polymer component may contain a polymer (second polymer) other than the first polymer. The polymer component may contain one kind of second polymer, or may contain plural kinds of second polymers.

The first segment contains more than 80% by mass of a monomer solution that is compatible with the coloring agent according to the compatibility determination test described in the examples below (in the case where the monomer solution cannot be prepared at 25°C When, it is a chain segment composed of the same monomer as the solution of the polymer formed by the monomer (the monomer is selected from the monomers listed below, for example). The coloring agent has compatibility with the first phase formed of such a first segment.

The glass transition temperature of the first segment (first glass transition temperature) is preferably 10°C or higher, more preferably 30°C or higher, still more preferably 60°C or higher, particularly preferably 90°C or higher. This configuration is suitable for suppressing the thermal mobility of the first segment forming the first phase of the adhesive layer 10 to stabilize the first phase, and therefore suitable for suppressing the heat of the toner having compatibility with the first phase. diffusion. The first glass transition temperature is preferably at most 120°C, more preferably at most 115°C, still more preferably at most 110°C. Such a configuration is suitable for achieving moderate softness in the adhesive layer 10 while ensuring good adhesion. In this embodiment, the first segment is a hard block.

Regarding the glass transition temperature (Tg) of a polymer (including a segment), a glass transition temperature (theoretical value) obtained based on the following Fox's formula can be used. Fox's formula is the relationship between the glass transition temperature Tg of the polymer and the glass transition temperature Tgi of the homopolymer of the monomers constituting the polymer. In the following formula of Fox, 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 temperature of the homopolymer formed from the monomer i (℃). Regarding the glass transition temperature of homopolymers, literature values can be used, for example, in "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) and "New Polymer Library 7 Introduction to Synthetic Resins for Coatings" (Kitaoka Association Three, Polymer Press, 1995), exemplified the glass transition temperature 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's formula 1/(273+Tg)=Σ[Wi/(273+Tgi)]

The second segment contains more than 80% by mass of the monomer solution that is judged to be incompatible with the coloring agent according to the compatibility determination test described in the examples below (the monomer solution cannot be prepared at 25° C. In this case, a segment consisting of the same monomer as the solution of the polymer formed from the monomer (the monomer is selected for example from the monomers listed below). The coloring agent has no compatibility with the second phase formed by such a second segment.

The second segment has a glass transition temperature (second glass transition temperature) lower than the above-mentioned first glass transition temperature. The second glass transition temperature is in a range lower than the first glass transition temperature, preferably not higher than 50°C, more preferably not higher than 10°C, further preferably not higher than 0°C, particularly preferably not higher than -20°C, especially preferably below -40°C. The second glass transition temperature is, for example, -150°C or higher. Also, the difference ΔTg between the first glass transition temperature and the second glass transition temperature is preferably at least 40°C, more preferably at least 80°C, still more preferably at least 100°C, particularly preferably at least 130°C, and most preferably at least 150°C. above. The difference ΔTg is preferably 200°C or lower, more preferably 190°C or lower, still more preferably 180°C or lower. These configurations related to the second glass transition temperature are suitable for achieving a moderate degree of softness in the adhesive layer 10 to ensure good adhesion. In this embodiment, such a second segment is a soft segment.

From the viewpoint of ensuring the adhesive force of the adhesive layer 10 , the mass ratio of the second segment (second phase) in the polymer component is preferably larger than the mass ratio of the first segment (first phase). The mass ratio of the second segment (second phase) in the polymer component is preferably at least 55% by mass, more preferably at least 60% by mass, still more preferably at least 65% by mass. That is, the mass ratio of the first segment (first phase) in the polymer component is preferably at most 45% by mass, more preferably at most 40% by mass, still more preferably at most 35% by mass. From the viewpoint of securing the dispersion density of the first phase in the adhesive layer 10, the mass ratio of the second segment (second phase) in the polymer component is preferably 80% by mass or less, more preferably 75% by mass or less, and more preferably 70% by mass or less. That is, the mass ratio of the first segment (first phase) in the polymer component is preferably at least 20% by mass, more preferably at least 25% by mass, and still more preferably at least 30% by mass.

When an acrylic polymer is used as a polymer component, the acrylic polymer is, for example, a copolymer containing a monomer component of an alkyl (meth)acrylate in a ratio of 50% by mass or more. "(Meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As an alkyl (meth)acrylate, the alkyl (meth)acrylate which has a linear or branched alkyl group of 1-20 carbon atoms is mentioned, for example. Such alkyl (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, Isopropyl (meth)acrylate, Isobutyl (meth)acrylate, Second-butyl (meth)acrylate, Tertiary-butyl (meth)acrylate, Amyl (meth)acrylate, (Meth) Isoamyl acrylate, Neopentyl (meth)acrylate, Hexyl (meth)acrylate, Heptyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, Octyl (meth)acrylate, Isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate Alkyl esters, lauryl (meth)acrylate, isotridecyl (meth)acrylate, myristyl (meth)acrylate, isotetradecyl (meth)acrylate, Pentadecyl (meth)acrylate, Cetyl (meth)acrylate, Heptadecyl (meth)acrylate, Octadecyl (meth)acrylate, Iso(meth)acrylate Octadecyl, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Alkyl (meth)acrylate may be used individually, or may use 2 or more types together. The preferred alkyl (meth)acrylate for forming the hard block and the preferred alkyl (meth)acrylate for forming the soft segment are described below.

From the viewpoint of making the adhesive layer 10 appropriately express basic properties such as adhesiveness, the ratio of the alkyl (meth)acrylate in the monomer component is preferably at least 50% by mass, more preferably at least 60% by mass. Furthermore, it is more preferable that it is 70 mass % or more. This ratio is, for example, 99% by mass or less.

The monomer component may contain a copolymerizable monomer copolymerizable with an alkyl (meth)acrylate. As a copolymerizable monomer, the monomer which has a polar group is mentioned, for example. As a polar group containing monomer, the monomer which has a hydroxyl group containing monomer, a nitrogen atom ring, and a carboxyl group containing monomer is mentioned, for example. Polar group-containing monomers are helpful for the modification of acrylic polymers, such as introducing crosslinking points into acrylic polymers, ensuring the cohesion of acrylic polymers, etc. From the viewpoint of modifying the acrylic polymer, the polar group-containing monomer may be included in the hard segment or in the soft segment.

The copolymerizable monomer preferably contains at least one selected from the group consisting of hydroxyl group-containing monomers, monomers having nitrogen atom rings, and carboxyl group-containing monomers. The copolymerizable monomer is more preferably a monomer containing a hydroxyl group-containing monomer and/or 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-hydroxy (meth)acrylate - Hydroxypropyl, 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. As a hydroxyl group-containing monomer, it is preferable to use 4-hydroxybutyl (meth)acrylate, and it is more preferable to use 2-hydroxybutyl acrylate.

From the viewpoint of introducing a crosslinked structure into the acrylic polymer and securing the cohesive force of the adhesive layer 10, the ratio of the hydroxyl group-containing monomer in the monomer component is preferably at least 1% by mass, more preferably 3% by mass or more, and more preferably 5% by mass or more. From the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility of various additive components in the adhesive layer 10 and the acrylic polymer), the ratio is preferably 30% by mass or less, more preferably 20% by mass. %the following.

As a monomer having a ring containing a nitrogen atom, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazole, N-vinylpyrrole, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazole, N-(meth)acryl-2 -Pyrrolidone, N-(meth)acrylpiperidine, N-(meth)acrylpyrrolidinium, N-vinyl 𠰌line, N-vinyl-3-𠰌linone, N-vinyl N-vinyl-2-caprolactamin, N-vinyl-1,3-㗁𠯤-2-one, N-vinyl-3,5-𠰌linedione, N-vinylpyrazole, N-vinyl Isoxazole, N-vinylthiazole, and N-vinylisothiazole. As a monomer having a ring containing a nitrogen atom, N-vinyl-2-pyrrolidone is preferably used.

From the viewpoint of ensuring the cohesive force of the adhesive layer 10 and the adhesion of the adhesive layer 10 to the adherend, the ratio of the monomer having a nitrogen atom ring in the monomer component is preferably 1% by mass or more, More preferably, it is 3 mass % or more, More preferably, it is 5 mass % or more. 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 of various additive components in the adhesive layer 10 and the acrylic polymer), this ratio is preferable. It is 30 mass % or less, More preferably, it is 20 mass % or less.

Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and methacrylic acid. .

From the viewpoint of introducing a cross-linked structure to the acrylic polymer, ensuring the cohesion of the adhesive layer 10, and ensuring the adhesion of the adhesive layer 10 to the adherend, the ratio of the carboxyl group-containing monomer in the monomer component is preferable. It is 1 mass % or more, More preferably, it is 3 mass % or more, More preferably, it is 5 mass % or more. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend due to acid, the ratio is preferably at most 30% by mass, more preferably at most 20% by mass.

The monomer component may also contain other copolymerizable monomers. As other copolymerizable monomers, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and Aromatic vinyl compounds.

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

As a sulfonic acid group-containing monomer, for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (methyl)sulfonic acid, base) acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloxynaphthalenesulfonic acid.

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

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

As a cyano group-containing monomer, acrylonitrile and methacrylonitrile are mentioned, for example.

As an alkoxy group-containing monomer, alkoxyalkyl (meth)acrylate and alkoxyalkylene glycol (meth)acrylate are mentioned, for example. Examples of alkoxyalkyl (meth)acrylates include 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, (meth)acrylic acid 2-Ethoxyethyl, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate. As alkoxy alkylene glycol (meth)acrylate, a methoxyethylene glycol (meth)acrylate, and a methoxy polypropylene glycol (meth)acrylate are mentioned, for example.

As an aromatic vinyl compound, styrene, (alpha)-methylstyrene, and vinyltoluene are mentioned, for example.

A copolymerizable monomer may be used individually or in combination of 2 or more types.

As a preferred monomer from the viewpoint of forming the above-mentioned hard block, for example, cyclic group-containing monomers, the above-mentioned polar group-containing monomers, and those having a relatively high glass transition temperature in homopolymers (a base) alkyl acrylate.

As a cyclic group containing monomer, an aliphatic ring containing monomer, an aromatic ring containing monomer, and a heterocyclic ring containing monomer are mentioned, for example. Examples of aliphatic ring-containing monomers include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isogeneric (IBXA) acrylate, 1,4-cyclohexyl Alkanedimethanol mono(meth)acrylate and 3,3,5-trimethylcyclohexyl acrylate are preferably IBXA. Examples of the aromatic ring-containing monomer include styrene, styrene derivatives, phenyl methacrylate, and benzyl methacrylate, and styrene is preferably used. Examples of styrene derivatives include α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethyl Styrene, and 4-ethylstyrene. As heterocyclic ring-containing monomers, for example, cyclic trimethylolpropane formal acrylate (CTFA), N-vinyl-2-pyrrolidone, and 4-acryloyl ? Preferably CTFA is used.

Examples of alkyl (meth)acrylates having a relatively high glass transition temperature in homopolymers include: methyl acrylate, alkyl acrylates having an alkyl group having 12 to 20 carbon atoms, alkyl acrylate having a carbon number of 1 Alkyl methacrylate with an alkyl group of ~6, and an alkyl methacrylate with an alkyl group with 14 to 20 carbons. As the alkyl (meth)acrylate forming the hard block, it is preferable to use an alkyl acrylate selected from methyl acrylate, an alkyl group having 12 to 20 carbons, and an alkyl group having 1 to 6 carbons. At least one selected from the group consisting of alkyl methacrylate, more preferably at least one selected from the group consisting of methyl acrylate and methyl methacrylate.

The polymer component preferably comprises a polymer selected from methyl methacrylate (MMA), a copolymer of MMA and 4-hydroxybutyl acrylate (4HBA), a polymer of styrene, a copolymer of styrene and 4HBA, Cyclic trimethylolpropane formal acrylate (CTFA) polymer, CTFA and 4HBA copolymer, isogeneric acrylate (IBXA) polymer, IBXA and 4HBA copolymer, CTFA, IBXA and 4HBA At least one of the group consisting of copolymer, methyl acrylate (MA), copolymer of IBXA and 4HBA, copolymer of IBXA and 4HBA, 4-acryloyl 𠰌line (ACMO), copolymer of acrylic acid (AA) and IBXA One as a hard block.

Alkyl (meth)acrylate whose glass transition temperature is relatively low among homopolymers is mentioned as a preferable monomer from a viewpoint of forming the said soft segment. As such an alkyl (meth)acrylate, the alkyl acrylate which has an alkyl group with 2-11 carbon atoms, and the alkyl methacrylate which has an alkyl group with 7-13 carbon atoms are mentioned, for example. As the alkyl (meth)acrylate forming the soft segment, it is preferable to use at least one selected from the group consisting of 2-ethylhexyl acrylate, dodecyl acrylate, and stearyl acrylate. A sort of. Also, the polymer component may contain a copolymer of 2EHA and 4HBA as a soft segment.

The acrylic polymer can be formed by polymerizing the above monomer components. As a polymerization method, for example, solution polymerization, block polymerization, and emulsion polymerization are mentioned, Preferably, solution polymerization is mentioned. Acrylic block polymers can be synthesized, for example, by living polymerization such as RAFT (Reversible Addition-Fragmentation Chain Transfer Polymerization) polymerization in solution to synthesize the first segment, and then containing The polymerization reaction is carried out in the solution of the monomer of the second segment and the first segment (in the RAFT polymerization, a RAFT agent as a chain transfer agent is used). Alternatively, the acrylic block polymer can also be synthesized as follows: after the second segment is synthesized by living polymerization such as RAFT polymerization in solution, the solution containing the monomer for forming the first segment and the second segment in the polymerization reaction. Acrylic graft polymers can be synthesized, for example, in a solution containing macromonomers (polymers having a polymerizable double bond at one end) for forming graft chains and monomers for elongating the polymer backbone. Polymerization. Alternatively, the acrylic graft polymer can also be synthesized, for example, by performing a polymerization reaction (graft polymerization) to elongate the polymer side chain after synthesizing the polymer main chain. As the polymerization initiator, for example, a thermal polymerization initiator can be used. The usage-amount of a polymerization initiator is 0.05 mass part or more with respect to 100 mass parts of monomer components, for example, and is 1 mass part or less, for example.

As a thermal polymerization initiator, an azo polymerization initiator and a peroxide polymerization initiator are mentioned, for example. As an azo polymerization initiator, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis( Dimethyl 2-methylpropionate, 4,4'-azobis-4-cyanopentanoic acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane)di Hydrochloride, 2,2'-Azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-Azobis(2-methyl propionamidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride. As a peroxide polymerization initiator, dibenzoyl peroxide, t-butyl peroxymaleate, and lauryl peroxide may be mentioned, for example.

From the viewpoint of securing the cohesive force of the adhesive layer 10, the weight average molecular weight of the acrylic polymer is preferably at least 100,000, more preferably at least 300,000, and still more preferably at least 500,000. The weight average molecular weight is preferably at most 5,000,000, more preferably at most 3,000,000, still more preferably at most 2,000,000. The weight-average molecular weight of the acrylic polymer can be measured by gel permeation chromatography (GPC), and calculated in terms of polystyrene.

The glass transition temperature (Tg) of the acrylic polymer is preferably at most 0°C, more preferably at most -10°C, further preferably at most -20°C. The glass transition temperature is, for example, -80°C or higher.

From the viewpoint of introducing a crosslinked structure into the polymer component, the adhesive composition may contain a crosslinking agent. As the crosslinking agent, for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an azoline crosslinking agent, an aziridine crosslinking agent, a carbodiimide crosslinking agent, and a metal chelate crosslinking agent may be mentioned. joint agent. A crosslinking agent may be used individually, or may use 2 or more types together.

As the isocyanate crosslinking agent, for example, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, Hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenylisocyanate. Moreover, as an isocyanate crosslinking agent, the derivative|guide_body of these isocyanate is also mentioned. As this isocyanate derivative, an isocyanurate modified body and a polyol modified body are mentioned, for example. Examples of commercially available isocyanate crosslinking agents include: Coronate L (trimethylolpropane adduct of toluene diisocyanate, manufactured by Tosoh), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate) Propane adduct, manufactured by Tosoh), Coronate HX (isocyanurate form of hexamethylene diisocyanate, manufactured by Tosoh), and Takenate D110N (trimethylolpropane addition of xylylene diisocyanate material, manufactured by Mitsui Chemicals).

As the epoxy crosslinking agent, bisphenol A, epichlorohydrin type epoxy resin, vinyl glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1 , 6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N,N,N',N'-tetraglycidyl-isophenylene Methylamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

From the viewpoint of securing the cohesive force of the adhesive layer 10, the compounded amount of the crosslinking agent is, for example, at least 0.01 parts by mass, preferably at least 0.05 parts by mass, and more preferably at least 0.07 parts by mass relative to 100 parts by mass of the polymer component. above. From the viewpoint of ensuring good adhesiveness of the adhesive layer 10, the compounding amount of the crosslinking agent is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass relative to 100 parts by mass of the polymer component. Parts by mass or less.

In the case of introducing a crosslinked structure into the polymer component, a crosslinking catalyst may be used in order to efficiently advance the crosslinking reaction. As the cross-linking catalyst, for example, dibutyltin dilaurate, tetra-n-butyl titanate, tetraisopropyl titanate, iron triacetylacetonate, and butyltin oxide, preferably dibutyltin dilaurate . The usage-amount of a crosslinking catalyst is 0.0001 mass part or more and 1 mass part or less with respect to 100 mass parts of polymer components, for example.

In the case of using a crosslinking catalyst, a crosslinking inhibitor that can be removed from the adhesive composition afterward can also be formulated in the adhesive composition. When dibutyltin dilaurate is used as a crosslinking catalyst, it is preferable to use acetylacetone as a crosslinking inhibitor. In this case, in the adhesive composition, acetylacetone is coordinated to dibutyltin dilaurate, and the crosslinking reaction of the crosslinking agent to the polymer component is suppressed. In the following production process of the adhesive sheet S, after the adhesive composition is coated on the release film to form a coating film, the acetylacetone can be volatilized by heating at a desired point, so that it can be self-coated. film removal. Thereby, the crosslinking reaction of a crosslinking agent can be advanced.

The compounding quantity of a crosslinking inhibitor is 100 mass parts or more with respect to 100 mass parts of crosslinking catalysts, Preferably it is 1000 mass parts or more. Moreover, this compounding quantity is 5000 mass parts or less, for example.

The coloring agent is compatible with the first phase and not compatible with the second phase. The coloring agent is preferably a compound that develops color by reaction with an acid (color-developing compound). When the coloring agent is a color-developing compound, the adhesive composition further contains a photoacid generator.

Examples of the color-forming compound include leuco dyes, triarylmethane dyes, diphenylmethane dyes, fluorane dyes, spiropyran dyes, and rhodamine dyes. A color-forming compound may be used individually or in combination of 2 or more types.

As a leuco pigment, for example, 2'-anilino-6'-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalactone-3,9'- [9H]dibenzopyran], 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dipropylamino-6-methyl-7-anilinofluoran, 3-Diethylamino-6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6- Methyl-7-xylanilinofluorane, and 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindole-3- base)-4-azaphthalide.

As a triarylmethane dye, p,p',p''-tri-dimethylaminotriphenylmethane may be mentioned, for example. As a diphenylmethane dye, 4,4-bis- dimethylaminophenyl benzhydryl benzyl ether is mentioned, for example. As a fluoran dye, 3-diethylamino-6-methyl-7-chlorofluoran is mentioned, for example. As the spiropyran dye, 3-methylspirobinapyran may, for example, be mentioned. As a rhodamine dye, rhodamine-B-anilinolactam is mentioned, for example.

From the viewpoint of ensuring good colorability of the adhesive layer 10, it is preferable to use a leuco pigment as a color-developing compound, and it is more preferable to use 2'-anilino-6'-(N-ethyl-N -isoamylamino)-3'-methylspiro[phthalide-3,9'-[9H]dibenzopyran].

The compounded amount of the color-developing compound is preferably at least 0.5 part by mass, more preferably at least 1 part by mass, relative to 100 parts by mass of the polymer component. The compounding amount is preferably at most 10 parts by mass, more preferably at most 7 parts by mass.

A photoacid generator generates an acid when it is irradiated with active energy rays as an external stimulus. Therefore, in the part of the adhesive layer 10 irradiated with active energy rays, an acid is generated by the photoacid generator, and the color-developing compound is developed by the acid. It is preferable that the photoacid generator has compatibility with the 1st phase and does not have compatibility with the 2nd phase from a viewpoint of making a color-developing compound develop color favorably. The portion of the adhesive layer 10 irradiated with active energy rays is colored, for example, in a dark color by the color development of the color-forming compound. The type of active energy ray is determined by the type of photoacid generator (specifically, the wavelength of the active energy ray that the 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 the variety of equipment used and ease of operation, ultraviolet rays are preferable as the active energy rays.

As a photoacid generator, the onium compound which generate|occur|produces acid by ultraviolet-ray irradiation is mentioned, for example. Onium compounds are provided, for example, in the form of onium salts of onium cations and anions. Examples of onium cations include iodonium and permeum. 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 ^- . A photoacid generator may be used individually or in combination of 2 or more types. The adhesive composition preferably contains an onium salt (onium compound) containing caldium and C ₄ F ₉ HSO ₃ ^- as a photoacid generator.

The compounded amount of the acid generator is preferably at least 1 part by mass, more preferably at least 2 parts by mass, further preferably at least 5 parts by mass, particularly preferably at least 7 parts by mass, based on 100 parts by mass of the polymer component. The compounding amount is preferably at most 20 parts by mass, more preferably at most 15 parts by mass, further preferably at most 12 parts by mass.

Moreover, the compounding quantity of an acid generator is 100 mass parts or more with respect to 100 mass parts of color developing compounds, Preferably it is 200 mass parts or more, More preferably, it is 300 mass parts or more, More preferably, it is 330 mass parts or more. The compounding amount is preferably at most 1000 parts by mass, more preferably at most 700 parts by mass, still more preferably at most 500 parts by mass.

The adhesive composition may contain other components as needed. As other components, a silane coupling agent, an adhesiveness imparting agent, a plasticizer, a softener, an antioxidant, a surfactant, and an antistatic agent are mentioned, for example.

The adhesive sheet S can be produced, for example, by applying the above-mentioned adhesive composition on a release film (first release film) to form a coating film, and then drying the coating film (indicated by a phantom line in FIG. 1 ). An adhesive sheet S) is disposed on the release film L.

As a release film (release liner), for example, a flexible plastic film may be mentioned. As this plastic film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, and a polyester film are mentioned, for example. The thickness of the release film is, for example, 3 μm or more and, for example, 200 μm or less. The surface of the release film is preferably subjected to a release treatment.

As the coating method of the adhesive composition, for example, roll coating, touch roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, rod coating, Blade 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. The drying time is, for example, 5 seconds to 20 minutes.

When the adhesive composition contains a crosslinking agent, the crosslinking reaction is advanced by performing aging simultaneously with the above-mentioned drying or aging after drying. Aging conditions are appropriately set according to 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.

Before aging or after aging, a release film (second release film) may be further laminated on the adhesive layer 10 on the first release film. The second release film is a flexible plastic film with surface release treatment, which is the same as that described above for the first release film.

In this way, an adhesive sheet S whose adhesive surface is protected by a release film coating can be manufactured. When using the adhesive sheet S, each peeling film peels from the adhesive sheet S as needed.

From the viewpoint of securing sufficient adhesiveness to the adherend, the thickness of the adhesive layer 10 is preferably at least 10 μm, more preferably at least 15 μm. From the viewpoint of the handleability of the adhesive sheet S, the thickness of the adhesive layer 10 is preferably 300 μm or less, more preferably 200 μm or less, further preferably 100 μm or less, especially preferably 50 μm or less.

The haze of the adhesive layer 10 (haze before an external stimulus is applied to the adhesive layer 10 ) is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less. Such a configuration is suitable for checking whether there are foreign substances and air bubbles between the adhesive sheet S and the adherend after the adhesive sheet S is bonded 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" by Murakami Color Technology Laboratory Co., Ltd. are mentioned, for example.

The average transmittance of the adhesive layer 10 at a wavelength of 400 to 700 nm (the average transmittance before an external stimulus is applied to the adhesive layer 10 ) is preferably at least 80%, more preferably at least 85%, and still more preferably at least 90%. above. Such a configuration is suitable for checking whether there are foreign substances and air bubbles between the adhesive sheet S and the adherend after the adhesive sheet S is bonded to the adherend.

The adhesion of the adhesive sheet S to the stainless steel plate in the peeling test at 23°C, a peeling angle of 180°, and a peeling speed (tensile speed) of 300 mm/min after being attached to a glass plate is as follows: It is 1 N/25 mm or more and, for example, 50 N/25 mm or less.

In the adhesive sheet S, the first discoloration width W1 of the discoloration region formed in the adhesive layer 10 by linearly applying external stimuli to the adhesive layer 10, and the adhesive layer 10 at 85°C 10 The second discoloration width W2 of the discoloration region after heat treatment for 120 hours satisfies the following formula (1).

0.5≦W2/W1≦1.6・・・(1)

Such a configuration is suitable for suppressing deterioration (bleeding, discoloration, unevenness of color tone, etc.) of the discolored part formed on the adhesive layer 10, and thus contributes to maintaining the functional characteristics of the discolored part. From this viewpoint, the ratio of W2 to W1 is preferably at least 0.65, more preferably at least 0.90, and more preferably at most 1.2.

The first discoloration width W1 of the discoloration region formed in the adhesive layer 10 by linearly imparting external stimuli to the adhesive layer 10 , and then the adhesive layer 10 was tested at 65°C and a relative humidity of 90%. The third discoloration width W3 of the discoloration region after the 120-hour heat treatment satisfies the following formula (2).

0.5≦W3/W1≦1.6・・・(2)

Such a configuration is suitable for suppressing deterioration (bleeding, discoloration, unevenness of color tone, etc.) of the discolored part formed on the adhesive layer 10, and thus contributes to maintaining the functional characteristics of the discolored part. From this viewpoint, the ratio of W3 to W1 is preferably at least 0.65, more preferably at least 0.90, and more preferably at most 1.2.

As shown in FIG. 3 , the adhesive sheet S may be a single-sided adhesive sheet with a base material 20 in addition to the adhesive layer 10 . In this case, specifically, the adhesive sheet S is provided with the adhesive layer 10 and the base material 20 arrange|positioned at one surface side of the thickness direction. Preferably, the substrate 20 is in contact with one side of the adhesive layer 10 in the thickness direction.

The substrate 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 polyolefins include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene /vinyl acetate copolymer, ethylene/ethyl acrylate copolymer, and ethylene/vinyl alcohol copolymer. As polyester, polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate may be mentioned, for example. As the polyamide, for example, polyamide 6, polyamide 6,6, and partially aromatic polyamide may be mentioned. As for the base material 20 , the plastic material of the base material 20 is preferably polyester, more preferably polyethylene terephthalate, in terms of both transparency and mechanical strength.

The base material 20 has transparency. The haze of the substrate 20 is preferably 3% or less, more preferably 2% or less, and 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 substrate 20 on the side of the adhesive layer 10 may be subjected to physical treatment, chemical treatment, or primer treatment for improving the adhesion with the adhesive layer 10 . As physical treatment, corona treatment and plasma treatment are mentioned, for example. As chemical treatment, acid treatment and alkali treatment are mentioned, for example.

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

The adhesive sheet S shown in FIG. 3 can be manufactured by the method similar to the said adhesive sheet manufacturing method except using the base material 20 instead of the 1st release film, for example.

4A to 4C show an example of how to use the adhesive sheet S. As shown in FIG. The method includes a preparation step, a joining step, and a discoloration part forming step.

First, in the preparation step, as shown in FIG. 4A , 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 can be other electronic devices and optical devices. The second member 32 is, for example, a transparent base material. As a transparent base material, a transparent plastic base material and a transparent glass base material are mentioned.

Next, in the bonding step, as shown in FIG. 4B , the first member 31 and the second member 32 are bonded via the adhesive sheet S. As shown in FIG. In this way, a laminate Z is obtained. In the laminate Z, the adhesive sheet S is arranged so as to be in contact with one side of the first member 31 in the thickness direction, and the second member 32 is arranged so as to be in contact with one side of the adhesive sheet S in the thickness direction.

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

Next, in the discoloration portion forming step, as shown in FIG. 4C , an external stimulus is applied to the adhesive layer 10 in the laminate Z to form the discoloration portion 11 in the adhesive layer 10 . Specifically, active energy rays are irradiated to the adhesive layer 10 as an external stimulus from the side of the transparent second member 32 through a mask pattern (not shown) for masking a specific region of the adhesive layer 10 . Thereby, the part of the adhesive layer 10 that is not covered by the mask pattern is changed in color.

As a light source for active energy ray irradiation in this step, an ultraviolet LED (Light Emitting Diode, light emitting diode) lamp, a high pressure mercury lamp, and a metal halide lamp are mentioned, for example. In addition, in the active energy ray irradiation in this step, a wavelength cutoff filter for cutting off a part of the wavelength region of the active energy ray emitted from the light source may be optionally used.

In this step, in the portion of the adhesive layer 10 irradiated with active energy rays, an acid is generated by the photoacid generator, and the color-developing compound is developed by reacting with the acid. Thereby, the discoloration part 11 is formed on the adhesive layer 10 .

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

In the adhesive sheet S, as mentioned above, the adhesive layer 10 contains the coloring agent which can develop color by external stimulation. Therefore, after attaching the adhesive sheet S to the adherend (in this embodiment, the members 31 and 32), by applying an external stimulus to the portion to be discolored in the adhesive layer 10, the adhesive layer 10 can be discolored. Partial discoloration. The adhesive sheet S that can form the discolored portion 11 on the adhesive layer 10 after being attached to the adherend can inspect the gap between the adhesive sheet S and the adherend after lamination and before the discolored portion 11 of the adhesive layer 10 is formed Check for foreign matter and air bubbles.

In addition, in the adhesive sheet S, as described above, the adhesive layer 10 includes a polymer component having a microphase-separated structure including a first phase and a second phase, and the color-developing compound as a colorant has an effect on Compatibility with the first phase, and no compatibility with the second phase.

In addition, in the adhesive sheet 10, as described above, the polymer component in the adhesive layer 10 includes a polymer having a first segment forming the first phase and a second segment forming the second phase in the molecule. 2 segments, the glass transition temperature of the first segment is above 10°C. This configuration is suitable for suppressing the thermal mobility of the first segment forming the first phase of the adhesive layer 10 to stabilize the first phase, and therefore suitable for suppressing the heat of the toner having compatibility with the first phase. diffusion. In such an adhesive sheet S, the color-forming compound tends to remain in the region of the first phase after the color-changing portion is formed on the adhesive layer 10 (that is, after the color-forming compound is colored by an external stimulus). , suitable for suppressing the movement (diffusion, etc.) of the color-forming compound in the adhesive layer 10 . By suppressing the movement of the color-forming compound, the deterioration of the discolored part (bleeding, fading, unevenness of the color tone, etc.) is suppressed.

Furthermore, in the adhesive sheet 10, as described above, the second glass transition temperature of the second segment of the polymer component is lower than the first glass transition temperature of the first segment, and the first glass transition temperature is 120° C. below ℃. Such a configuration is suitable for achieving moderate softness in the adhesive layer 10 while ensuring good adhesion.

As described above, the adhesive sheet S can discolor at least a part of the adhesive layer 10 after being attached to an adherend, and is suitable for suppressing deterioration of the discolored portion of the adhesive layer 10 . Inhibiting the deterioration of the discolored portion of the adhesive layer 10 helps to maintain the functional properties of the discolored portion such as designability, light-shielding properties, and anti-reflection properties. [Example]

Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to an Example. In addition, the specific numerical values such as the blending amount (content), physical property values, and parameters described below can be replaced with the corresponding upper limits of the blending amount (content), physical property values, parameters, etc. described in the above-mentioned "embodiment" (defined as A value that is "below" or "under") or a lower limit (defined as a value that is "above" or "exceeded").

[Example 1] ＜Preparation of polymer components＞ In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet pipe, 95 parts by mass of styrene, 5 parts by mass of 4-hydroxybutyl acrylate (4HBA), and trithiocarbonic acid = 1.45 parts by mass of bis{4-[ethyl-(2-acetyloxyethyl)carbamoyl]benzyl} ester, 2,2'-azobis(isobutyric acid) as a polymerization initiator A mixture of 0.12 parts by mass of dimethyl ester and 36 parts by mass of anisole as a solvent was stirred at 130° C. under a nitrogen atmosphere for 7 hours (polymerization reaction). A copolymer of styrene and 4HBA (styrene-4HBA copolymer) is thereby obtained. The weight average molecular weight (Mw) of the copolymer was 26,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned styrene-4HBA copolymer (solid A mixture of 0.04 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 57 parts by mass of ethyl acetate as a solvent was carried out under nitrogen at 75°C Stirring was carried out under atmosphere for 7 hours (polymerization). Thus, a first polymer solution containing an acrylic block polymer (polymer P ₁ ) was obtained. The weight average molecular weight (Mw) of the polymer P1 in the _first polymer solution was 86,000. In addition, polymer P1 has _a styrene-4HBA copolymer block (first polymer block) as a hard block (first segment) and a 2EHA block as a soft segment (second segment). segment (second polymer block) of an acrylic block polymer.

<Preparation of Adhesive Composition> To the _first polymer solution containing polymer P1, _an isocyanate crosslinking agent (trade name " Takenate D110N", a 75% ethyl acetate solution of a trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals Co., Ltd.) 0.25 parts by mass (converted amount of solid content), as the second crosslinking catalyst Dibutyltin laurate (trade name "OL-1", 1% by mass ethyl acetate solution, manufactured by Tokyo Fine Chemical Co., Ltd.) 0.01 parts by mass (in terms of solid content), as a crosslinking inhibitor (for the crosslinking catalyst Ligand) acetylacetone 3 parts by mass, leuco pigment (trade name "S-205", 2'-anilino-6'-(N-ethyl-N-isoamyl Amino)-3'-methylspiro[phthalactone-3,9'-[9H]dibenzopyran], manufactured by Yamada Chemical Industry Co., Ltd.) 2 parts by mass, and a photoacid generator (trade name "SP -056", an onium salt of calcite and C ₄ F ₉ HSO ₃ ^- , manufactured by ADEKA) 7 parts by mass were mixed to prepare an adhesive composition.

＜Formation of Adhesive Layer＞ An adhesive composition was applied to the release-treated surface of a 38 μm-thick base film (trade name "MRF#38", polyester film, manufactured by Mitsubishi Plastics Corporation) that had been released on one side to form a coating film. Next, this coating film was dried by heating at 132 degreeC for 3 minutes. Thereby, an adhesive layer with a thickness of 25 μm was formed on the base film. Next, attach the release-treated side of a release film with a thickness of 38 μm (trade name "MRE#38", polyester film, manufactured by Mitsubishi Plastics Corporation) that has been released on one side to the adhesive on the base film Floor. Thereafter, aging treatment was carried out at 60° C. for 24 hours, so that the cross-linking reaction in the adhesive layer proceeded. The adhesive sheet of Example 1 was produced in the above-mentioned manner. The polymer component in the adhesive sheet of Example 1 and the composition of the adhesive layer are shown in Table 1 with the unit being parts by mass (the same applies to the following Examples and Comparative Examples).

[Example 2] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction pipe, a giant solution containing 75 parts by mass of 2-ethylhexyl acrylate (2EHA) and methyl methacrylate (MMA) was 20 parts by mass of monomer (trade name "AA-6", manufactured by Toagosei Co., Ltd.), 5 parts by mass of 4-hydroxybutyl acrylate (4HBA), 2,2'-azobisisobutyronitrile as a polymerization initiator A mixture of 0.2 parts by mass of (AIBN), 80 parts by mass of ethyl acetate as a solvent, and 50 parts by mass of methyl ethyl ketone was stirred at 60° C. under a nitrogen atmosphere for 7 hours (polymerization reaction). Thus, a second polymer solution containing an acrylic acid graft polymer (polymer P ₂ ) was obtained. The weight average molecular weight (Mw) of the polymer P2 in the _second polymer solution was 350,000. In addition, polymer P2 has a polymer main chain as a soft segment ( _second segment) including the main component 2EHA, and a polymer side chain as a hard block (first segment) including the main component MMA acrylic graft polymers. Then, the adhesive sheet of Example 2 was produced in the same manner as the adhesive sheet of Example 1 except that the second polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Example 3] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 95 parts by mass of cyclic trimethylolpropane formal acrylate (CTFA), 5 parts by mass of 4-hydroxybutyl acrylate (4HBA) Parts, 1.45 parts by mass of trithiocarbonic acid=bis{4-[ethyl-(2-acetyloxyethyl)aminoformyl]benzyl} ester as a chain transfer agent, 2 parts by mass as a polymerization initiator , A mixture of 0.061 parts by mass of dimethyl 2'-azobis(isobutyrate) and 67 parts by mass of ethyl acetate as a solvent was stirred at 75° C. under a nitrogen atmosphere for 7 hours (polymerization reaction). A copolymer of CTFA and 4HBA (CTFA-4HBA copolymer) was thus obtained. The weight average molecular weight (Mw) of the copolymer was 29,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction pipe, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned CTFA-4HBA copolymer (solid matter Component conversion amount), a mixture of 0.033 parts by mass of 2,2'-azobis(isobutyrate) dimethyl ester as a polymerization initiator, and 100 parts by mass of ethyl acetate as a solvent was carried out at 75°C in a nitrogen atmosphere Stirring was continued for 7 hours (polymerization). Thus, a third polymer solution containing an acrylic block polymer (polymer P ₃ ) was obtained. The weight average molecular weight (Mw) of the polymer _P3 in the third polymer solution was 94,000. Also, polymer _P3 has a CTFA-4HBA copolymer block (first polymer block) as a hard block (first segment) and a 2EHA block as a soft segment (second segment) (2nd polymer block) acrylic block polymer.

Then, the adhesive sheet of Example 3 was produced in the same manner as the adhesive sheet of Example 1 except that the third polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Example 4] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 47.5 parts by mass of cyclic trimethylolpropane formal acrylate (CTFA) and 47.5 parts by mass of isogeneric acrylate (IBXA) , 5 parts by mass of 4-hydroxybutyl acrylate (4HBA), trithiocarbonic acid=bis{4-[ethyl-(2-acetyloxyethyl)carbamoyl]benzyl} as a chain transfer agent A mixture of 0.77 parts by mass of ester, 0.073 parts by mass of dimethyl 2,2'-azobis(isobutyrate) as a polymerization initiator, and 67 parts by mass of ethyl acetate as a solvent was carried out under a nitrogen atmosphere at 75°C Stirring was continued for 7 hours (polymerization). A copolymer of CTFA, IBXA and 4HBA (CTFA-IBXA-4HBA copolymer) was thus obtained. The weight average molecular weight (Mw) of the copolymer was 59,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction pipe, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned CTFA-IBXA-4HBA copolymer ( solid content conversion), a mixture of 0.029 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 100 parts by mass of ethyl acetate as a solvent was heated at 75°C Stir under nitrogen atmosphere for 7 hours (polymerization). Thus, a fourth polymer solution containing an acrylic block polymer (polymer P ₄ ) was obtained. The weight average molecular weight (Mw) of the polymer P4 in this _4th polymer solution was 165,000. Also, polymer P4 has a CTFA _- IBXA-4HBA copolymer block (first polymer block) as a hard block (first segment) and 2EHA as a soft segment (second segment) Block (second polymer block) acrylic block polymer.

Then, the adhesive sheet of Example 4 was produced in the same manner as the adhesive sheet of Example 1 except that the fourth polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Example 5] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 27.5 parts by mass of cyclic trimethylolpropane formal acrylate (CTFA) and 67.5 parts by mass of isogeneric acrylate (IBXA) , 5 parts by mass of 4-hydroxybutyl acrylate (4HBA), trithiocarbonic acid=bis{4-[ethyl-(2-acetyloxyethyl)carbamoyl]benzyl} as a chain transfer agent A mixture of 0.76 parts by mass of ester, 0.073 parts by mass of dimethyl 2,2'-azobis(isobutyrate) as a polymerization initiator, and 67 parts by mass of ethyl acetate as a solvent was carried out at 75°C in a nitrogen atmosphere Stirring was continued for 7 hours (polymerization). A copolymer of CTFA, IBXA and 4HBA (CTFA-IBXA-4HBA copolymer) was thus obtained. The weight average molecular weight (Mw) of the copolymer was 63,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction pipe, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned CTFA-IBXA-4HBA copolymer ( solid content conversion), a mixture of 0.029 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 100 parts by mass of ethyl acetate as a solvent was heated at 75°C Stir under nitrogen atmosphere for 7 hours (polymerization). Thus, a fifth polymer solution containing an acrylic block polymer (polymer P ₅ ) was obtained. The weight average molecular weight (Mw) of the polymer P5 in the _fifth polymer solution was 164,000. In addition, polymer _P5 has a CTFA-IBXA-4HBA copolymer block (first polymer block) as a hard block (first segment) and 2EHA as a soft segment (second segment) Block (second polymer block) acrylic block polymer.

Then, the adhesive sheet of Example 5 was produced in the same manner as the adhesive sheet of Example 1 except that the fifth polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Example 6] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 47.5 parts by mass of isogeneric acrylate (IBXA), 47.5 parts by mass of methyl acrylate (MA), 4-hydroxybutyl acrylate ( 4HBA) 5 parts by mass, 0.50 parts by mass of trithiocarbonic acid=bis{4-[ethyl-(2-acetyloxyethyl)carbamoyl]benzyl} ester as a chain transfer agent, as a polymerizer A mixture of 0.019 parts by mass of 2,2'-azobis(isobutyrate) dimethyl ester as an initiator and 67 parts by mass of ethyl acetate as a solvent was stirred at 75°C for 7 hours under a nitrogen atmosphere (polymerization reaction) . A copolymer of IBXA, MA and 4HBA (IBXA-MA-4HBA copolymer) was thus obtained. The weight average molecular weight (Mw) of the copolymer was 98,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction pipe, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned IBXA-MA-4HBA copolymer ( solid content conversion), a mixture of 0.069 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 100 parts by mass of ethyl acetate as a solvent was heated at 75°C Stir under nitrogen atmosphere for 7 hours (polymerization). Thus, a sixth polymer solution containing an acrylic block polymer (polymer P ₆ ) was obtained. The weight average molecular weight (Mw) of the polymer P6 in the _sixth polymer solution was 165,000. In addition, polymer P ₆ has an IBXA-MA-4HBA copolymer block (first polymer block) as a hard block (first segment) and 2EHA as a soft segment (second segment) Block (second polymer block) acrylic block polymer.

Then, the adhesive sheet of Example 6 was produced in the same manner as the adhesive sheet of Example 1 except that the sixth polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Example 7] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 48.5 parts by mass of 4-acryloylmethanol (ACMO), 48.5 parts by mass of isogeneric acrylate (IBXA), acrylic acid (AA) 3 parts by mass, 1.41 parts by mass of trithiocarbonic acid=bis{4-[ethyl-(2-acetyloxyethyl)aminoformyl]benzyl} ester as a chain transfer agent, as a polymerization initiator A mixture of 0.13 parts by mass of 2,2'-azobis(isobutyrate) dimethyl and 63 parts by mass of ethyl acetate as a solvent was stirred at 75° C. for 7 hours under a nitrogen atmosphere (polymerization reaction). A copolymer of ACMO, IBXA and AA (ACMO-IBXA-AA copolymer) was thus obtained. The weight average molecular weight (Mw) of the copolymer was 36,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction pipe, 70 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of the above-mentioned ACMO-IBXA-AA copolymer ( solid content conversion), a mixture of 0.19 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 67 parts by mass of ethyl acetate as a solvent was heated at 75°C Stir under nitrogen atmosphere for 7 hours (polymerization). Thus, a seventh polymer solution containing an acrylic block polymer (polymer P ₇ ) was obtained. The weight average molecular weight (Mw) of the polymer P7 in the _seventh polymer solution was 99,000. In addition, polymer P7 has an ACMO _- IBXA-AA copolymer block (first polymer block) as a hard block (first segment) and 2EHA as a soft segment (second segment) Block (second polymer block) acrylic block polymer.

Then, the adhesive sheet of Example 7 was produced in the same manner as the adhesive sheet of Example 1 except that the seventh polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Comparative Example 1] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet pipe, 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of methyl methacrylate (MMA) parts, 13 parts by mass of 2-hydroxyethyl acrylate (HEA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 2,2'-azobisisobutyronitrile ( AIBN) 0.2 mass parts, and the mixture of 233 mass parts of ethyl acetate as a solvent were stirred at 60 degreeC under nitrogen atmosphere for 7 hours (polymerization reaction). Thus, an eighth polymer solution containing an acrylic polymer (polymer P ₈ ) was obtained. The weight average molecular weight (Mw) of the polymer P8 in this _8th polymer solution was 1.2 million. Also, polymer _P8 is a random copolymer. Then, the adhesive sheet of Comparative Example 1 was produced in the same manner as the adhesive sheet of Example 1 except that the eighth polymer solution was used instead of the first polymer solution when preparing the adhesive composition.

[Comparative example 2] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet pipe, 100 parts by mass of phenoxyethyl acrylate (PEA) and trithiocarbonic acid = bis{4-[B 1.41 parts by mass of base-(2-acetyloxyethyl)carbamoyl]benzyl} ester, 0.13 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator , and a mixture of 100 parts by mass of ethyl acetate as a solvent was stirred at 75° C. under a nitrogen atmosphere for 7 hours (polymerization reaction). Thereby a PEA polymer is obtained. The polymer has a weight average molecular weight (Mw) of 42,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 66.5 parts by mass of 2-ethylhexyl acrylate (2EHA), 3.5 parts by mass of 4-hydroxybutyl acrylate (4HBA) , 30 parts by mass of the above-mentioned PEA polymer (in terms of solid content), 0.17 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 67 parts by mass of ethyl acetate as a solvent The mixture in parts by mass was stirred at 75° C. for 7 hours under a nitrogen atmosphere (polymerization). Thus, a ninth polymer solution containing an acrylic block polymer (polymer P ₉ ) was obtained. The weight average molecular weight (Mw) of the polymer P9 in the _ninth polymer solution was 295,000. In addition, polymer _P9 has a PEA polymer block (first polymer block) as a hard block (first segment) and a 2EHA-4HBA copolymer as a soft segment (second segment) Block (second polymer block) acrylic block polymer.

Then, the adhesive sheet of Comparative Example 2 was produced in the same manner as the adhesive sheet of Example 1 except that the ninth polymer solution was used instead of the above-mentioned first polymer solution when preparing the adhesive composition.

[Comparative example 3] In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, trithiocarbonic acid=bis{4-[ethyl-( 1.41 parts by mass of 2-acetyloxyethyl)carbamoyl]benzyl} ester, 0.13 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and A mixture of 100 parts by mass of ethyl acetate as a solvent was stirred at 75° C. under a nitrogen atmosphere for 7 hours (polymerization reaction). Thereby an MA polymer is obtained. The polymer has a weight average molecular weight (Mw) of 44,000.

Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 66.5 parts by mass of 2-ethylhexyl acrylate (2EHA), 3.5 parts by mass of 4-hydroxybutyl acrylate (4HBA) , 30 parts by mass of the above MA polymer (in terms of solid content), 0.15 parts by mass of 2,2'-azobis(isobutyrate) dimethyl as a polymerization initiator, and 100 parts by mass of ethyl acetate as a solvent The mixture in parts by mass was stirred at 75° C. for 7 hours under a nitrogen atmosphere (polymerization). Thus, a tenth polymer solution containing an acrylic block polymer (polymer P ₁₀ ) was obtained. The polymer P10 in the _tenth polymer solution had a weight average molecular weight (Mw) of 180,000. Also, polymer _P10 has a MA polymer block (first polymer block) as a hard block (first segment) and a 2EHA-4HBA block as a soft segment (second segment) (2nd polymer block) acrylic block polymer.

Then, the adhesive sheet of Comparative Example 3 was produced in the same manner as the adhesive sheet of Example 1 except that the tenth polymer solution was used instead of the above-mentioned first polymer solution when preparing the adhesive composition.

＜Presence or absence of microphase separation structure＞ About the adhesive layer of each adhesive sheet of Examples 1-7 and Comparative Examples 1-3, the presence or absence of a microphase separation structure was confirmed as follows. First, prepare a sample for transmission electron microscope (TEM) observation. Specifically, after the adhesive layer was dyed, it was rapidly frozen, and thin slices were cut out from the adhesive layer using an ultramicrotome (manufactured by Leica). Then, this thin section was observed and photographed using a transmission electron microscope (trade name "HT7820", manufactured by Hitachi High-Tech Co., Ltd.). Next, the obtained TEM image is analyzed and binarized by image analysis software.

In the adhesive layer of the adhesive sheet of Example 1, as shown in FIG. 5 , a microphase separation structure was confirmed. The microphase separation structure of the adhesive layer is a spherical structure as shown in FIG. 2A. Specifically, in the adhesive layer, benzene as a hard block (first segment) is dispersed in a matrix (second phase) formed by a 2EHA block as a soft segment (second segment). Disperse phase formed by ethylene-4HBA copolymer block.

In the adhesive layer of the adhesive sheet of Example 2, as shown in FIG. 6 , a microphase separation structure was confirmed. The microphase separation structure of the adhesive layer is a spherical structure as shown in FIG. 2A. Specifically, in the adhesive layer, in the matrix (second phase) formed by the polymer main chain which is the soft segment (second segment) containing the main components 2EHA and 4HBA, is dispersed as the main component The dispersed phase formed by the polymer side chains of the hard block (first segment) of MMA and 4HBA.

In the adhesive layer of the adhesive sheet of Example 4, as shown in FIG. 7 , a microphase separation structure was confirmed. It is speculated that the microphase separation structure of the adhesive layer is the cylindrical structure shown in FIG. 2B. Specifically, in the adhesive layer, CTFA as a hard block (first segment) is dispersed in a matrix (second phase) formed by a 2EHA block as a soft segment (second segment) - A dispersed phase formed by IBXA-4HBA copolymer blocks.

In the adhesive layer of the adhesive sheet of Example 5, as shown in FIG. 8 , a microphase separation structure was confirmed. It is speculated that the microphase separation structure of the adhesive layer is the cylindrical structure shown in FIG. 2B. Specifically, in the adhesive layer, CTFA as a hard block (first segment) is dispersed in a matrix (second phase) formed by a 2EHA block as a soft segment (second segment) - A dispersed phase formed by IBXA-4HBA copolymer blocks.

In the adhesive layer of Comparative Example 1, as shown in FIG. 9 , no microphase separation structure was confirmed.

In the adhesive layer of the adhesive sheet of Comparative Example 2, a microphase separation structure was confirmed. The microphase separation structure of the adhesive layer is a spherical structure as shown in FIG. 2A. Specifically, in this adhesive layer, in the matrix (second phase) formed by the isoprene block which is the soft segment (the second segment), dispersed as the hard block (the first segment) ) The dispersed phase formed by the styrene block.

In the adhesive layer of the adhesive sheet of Comparative Example 3, as shown in FIG. 10 , a microphase separation structure was confirmed. The microphase separation structure of the adhesive layer is a cylindrical structure as shown in FIG. 2B. Specifically, in this adhesive layer, in the matrix (second phase) formed by the isoprene block which is the soft segment (the second segment), dispersed as the hard block (the first segment) ) The dispersed phase formed by the styrene block.

<Glass transition temperature of segment> The glass transition temperature (first glass transition temperature) of the hard block (first segment) in the adhesive layer of each adhesive sheet of Examples 1 to 7 and Comparative Examples 2 and 3 was obtained according to the above-mentioned Fox's formula. The values thereof are shown in Table 1. On the other hand, the glass transition temperature (second glass transition temperature) of the soft segment (second segment formed by 2EHA) in the adhesive layer of each adhesive sheet of Examples 1 to 7 and Comparative Examples 2 and 3 is known. temperature) is -70°C. In any adhesive layer, the second glass transition temperature (-50° C.) is lower than the first glass transition temperature. Also, the difference between the first glass transition temperature and the second glass transition temperature is 160.6°C (Example 1), 175°C (Example 2), 93.3°C (Example 3), 122.2°C (Example 4), and 136.1°C (Example 5), 111.5°C (Example 6), 189.1°C (Example 7), 70.7°C (Comparative Example 2), and 73.2°C (Comparative Example 3).

＜Compatibility Judgment Test＞ Regarding each of the color-forming compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3, their compatibility with various monomer or polymer solutions was investigated.

Specifically, first, styrene, 4-hydroxybutyl acrylate (4HBA), methyl methacrylate (MMA), acrylic acid (AA), N-vinyl-2-pyrrolidone (NVP), acrylic acid 2 -Methoxyethyl ester (2MEA), methyl acrylate (MA), 2-ethylhexyl acrylate (2EHA), cyclic trimethylolpropane formal acrylate (CTFA), isogeneric acrylate (IBXA ), 4-acryloyl methanoline (ACMO), phenoxyethyl acrylate (PEA), lauryl acrylate (lauryl acrylate), stearyl acrylate (octadecyl acrylate) as monomer solution. As a monomer solution, a mixed solution of 95% by mass of styrene and 5% by mass of 4HBA was also prepared.

Next, in a 50 mL spiral tube, a mixture containing 7.8 g of the monomer solution and 0.2 g of compound C (color-forming compound or photoacid generator) (the ratio of compound C is 2.5% by mass) was stirred ( 1st stirring). The stirring system uses a magnetic stirrer. When stirring, the temperature was set at 25° C., the rotation speed of the stirrer was set at 500 rpm, and the stirring time was set at 5 minutes. After stirring, it was visually confirmed whether or not Compound C was dissolved in the monomer solution by such stirring without turbidity or precipitation. Color compounds and photoacid generators are dissolved in styrene, 4HBA, MMA, AA, NVP, 2MEA, CTFA, IBXA, ACMO, PEA, and MA, respectively, and 95% by mass of styrene and 5% by mass of 4HBA In the mixed solution, no turbidity or precipitation occurred (compound C showed compatibility). On the other hand, the chromogenic compound and the photoacid generator produced turbidity or precipitation to the respective solutions of 2EHA, lauryl acrylate, and stearyl acrylate (compound C did not show compatibility).

On the other hand, a polyisoprene solution was prepared as a polymer solution (a monomer solution of isoprene could not be prepared because the volatility of isoprene was too high). Next, in a 50 mL spiral tube, a mixture containing 7.8 g of the polymer solution and 0.2 g of compound C (color-developing compound or photoacid generator) (the ratio of compound C was 2.5% by mass) was stirred (para. 2 stirring). The conditions of the second stirring are the same as those of the above-mentioned first stirring. It was confirmed by observation after the second stirring that the chromogenic compound and the photoacid generator produced turbidity or precipitation with respect to the polymer solution, respectively (compound C did not show compatibility).

Then, it was determined that Compound C was a polymer formed from the monomer for a monomer solution containing 80% by mass or more of the monomer exhibiting the above-mentioned compatibility with Compound C (when the monomer solution could not be prepared at 25° C. The chain segment composed of the same monomer is compatible with the phase in the microphase separation structure formed by the polymer component having the chain segment. In addition, it was determined that compound C contained 80% by mass or more of a monomer solution that did not exhibit the above-mentioned compatibility with compound C (in the case where the monomer solution could not be prepared at 25°C, it was a polymerization reaction formed from the monomer). The chain segment composed of the same monomer is incompatible with the phase in the microphase separation structure formed by the polymer component having the chain segment. Specifically, as follows.

The color-forming compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 were formed in a microphase-separated structure with respect to the hard block (HS) containing 95% by mass of styrene and 5% by mass of 4HBA The inner phase (the first phase in Example 1) has compatibility. In HS in Example 1, the ratio of compound C showing compatibility monomer (styrene, 4HBA) was 80% by mass or more.

The color-developing compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 were formed in the microphase-separated structure of HS containing MMA as a main component (the first phase in Example 2). phase) are compatible. In HS in Example 2, the ratio of compound C showing compatibility monomers (MMA, 4HBA) was 80% by mass or more.

The chromogenic compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 were formed in the phase in the microphase separation structure (the first phase in Example 3) for HS including CTFA and 4HBA, respectively. ) are compatible. In HS in Example 3, the ratio of compound C showing compatibility monomers (CTFA, 4HBA) was 80% by mass or more.

The chromogenic compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 formed phases in the microphase-separated structure for HS including CTFA, IBXA and 4HBA (in Examples 4 and 5). Phase 1) is compatible. In HS in Examples 4 and 5, the ratio of compound C showing compatibility monomers (CTFA, IBXA, 4HBA) was 80% by mass or more.

The color-developing compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 respectively formed phases in the microphase-separated structure for HS including CTFA, MA and 4HBA (the first phase in Example 6). 1 phase) are compatible. In HS in Example 6, the ratio of compound C showing compatibility monomers (CTFA, MA, 4HBA) was 80% by mass or more.

The chromogenic compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 respectively formed phases in the microphase separation structure of HS including ACMO, IBXA and AA (the first phase in Example 7). 1 phase) are compatible. In HS in Example 7, the ratio of compound C showing compatibility monomers (ACMO, IBXA, AA) was 80% by mass or more.

The color-forming compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 were respectively for the phases in which the soft segment (SS) containing 2EHA as the main component was formed in the microphase separation structure (Example 1 to 7 and the second phase in Comparative Examples 2 and 3) are not compatible. In the SS in Examples 1 to 7 and Comparative Examples 2 and 3, the ratio of the monomer (2EHA) in which Compound C does not show compatibility was 80% by mass or more.

The color-developing compounds and photoacid generators used in Examples 1 to 7 and Comparative Examples 1 to 3 were used for the phases in which the soft segment (SS) containing isoprene as the main component was formed in the microphase separation structure. Not compatible.

＜Haze＞ About the adhesive layer of each adhesive sheet of Examples 1-7 and Comparative Examples 1-3, haze was investigated as follows. First, a sample for haze measurement is prepared. Specifically, after peeling off the release film (MRE#38) from the adhesive sheet, the adhesive layer side of the sheet (substrate film, adhesive layer) was attached to Eagle glass (thickness 0.55 mm, Matsunami Glass Co., Ltd. Manufacturing), the substrate film (MRF#38) was peeled off from the adhesive layer on the Eagle glass. Thereby, the sample for haze measurement (1st sample for measurement) was produced. Next, using a haze measurement device (trade name "HZ-1", manufactured by Suga Testing Instruments Co., Ltd.), the haze of the adhesive layer in the sample was measured (first haze measurement). In this measurement, the sample for measurement is set in the device so that light is irradiated onto the sample for measurement from the Eagle glass side of the sample for measurement. In addition, in this measurement, the measurement result obtained by measuring only about Eagle glass under the same conditions was used as a reference line. Table 1 shows the haze (before UV (ultraviolet) irradiation) of the adhesive layer obtained in this way.

On the other hand, about each adhesive sheet of Examples 1-7 and Comparative Examples 1-3, the haze after UV irradiation was investigated as follows.

First, the same sample as the above-mentioned first sample for measurement was produced. Next, the sample is irradiated with ultraviolet rays. Specifically, for the adhesive sheet (adhesive layer) in the sample, in an environment of 23°C and a relative humidity of 50%, ultraviolet rays are irradiated from the side of the Eagle glass through the glass (the adhesive layer is irradiated by the UV irradiation). The leuco pigment in it reacts with the photoacid generator). In this UV irradiation, a UV-LED lamp with a wavelength of 365 nm in a UV-LED irradiation device manufactured by Quark Technology (model "QEL-350-RU6W-CW-MY") was used as a light source, and the cumulative amount of irradiation light was set to 8000 mJ/cm ² (accumulated light intensity of irradiation within the wavelength range of 320-390 nm). A measurement sample (second measurement sample) was produced in the above-mentioned manner.

Next, for the sample for the second measurement, the haze of the adhesive layer in the sample was measured using a haze measuring device (trade name "HZ-1", manufactured by Suga Testing Instruments Co., Ltd.) (second haze measurement). Regarding the specific measurement method and conditions, the second haze measurement is the same as the above-mentioned first haze measurement. Table 1 shows the haze (after UV irradiation) of the adhesive layer obtained in this way.

＜Durability Test＞ Regarding the adhesive layer of each adhesive sheet of Examples 1-7 and Comparative Examples 1-3, the degree of change suppression of the formed discoloration part was investigated as follows.

First, a plurality of adhesive sheets were prepared for each of the adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 3.

Next, by irradiating ultraviolet rays to the adhesive layer of the adhesive sheet through a photomask having a linear opening, a linear discoloration portion is formed on the adhesive layer. The photomask is formed by the dry film photoresist arranged on the side surface of the substrate film in the adhesive sheet, and the line width of the opening of the photomask is about 200 μm (the line width of the opening of each photomask is different) . In ultraviolet irradiation, a UV-LED lamp with a wavelength of 365 nm in a UV-LED irradiation device manufactured by Quark Technology (model "QEL-350-RU6W-CW-MY") is used as a light source, and a photomask and a substrate are interposed The film was irradiated with ultraviolet rays to the adhesive layer, and the integrated light intensity of irradiation was set to 2000 mJ/cm ² (integrated light intensity of irradiation in the wavelength range of 320 to 390 nm).

Next, the line width of the linearly discolored portion formed in the adhesive layer was measured (measurement of the initial line width). Specifically, first, the linear discoloration part formed on the adhesive layer was observed with a digital microscope (trade name "VHX-900", manufactured by KEYENCE Corporation), and a part including the discoloration part and its vicinity were photographed at a magnification of 50 times. area. Next, binarize the captured image with image analysis software. Next, in the binarized image, the line width (W1) of the linearly discolored portion is measured.

Next, the adhesive sheet in which the linearly discolored portion was formed in the adhesive layer was heat-treated at 85° C. for 120 hours (first durability test).

Next, the line width of the linearly discolored portion in the adhesive layer of the adhesive sheet was measured. The specific measurement method is the same as that described above for the measurement of the initial line width. The line width W1 of the linear discolored part before the first durability test, the line width W2 of the linear discolored part after the first durability test, and the change from the line width W1 to the line width W2 (｜W2－W1｜ ), and the rate of change (W2/W1) of the line width W2 relative to the line width W1 are shown in Table 1. Also, regarding the degree of change inhibition of the discolored part, the case of 0.90≦W2/W1≦1.2 was evaluated as "excellent", and the case of 0.65≦W2/W1<0.9 or 1.2<W2/W1≦1.6 was evaluated as "good", The case where 0.50≦W2/W1<0.65 or 1.6<W2/W1≦2.0 was evaluated as "possible", and the case where W2/W1<0.50 or 2.0<W2/W1 was satisfied was evaluated as "impossible". The evaluation results are also shown in Table 1.

On the other hand, for the adhesive layers of the adhesive sheets of Examples 1 to 7 and Comparative Examples 1 to 3, the second durability test was carried out instead of the first durability test, and the same method as above was carried out. The degree of oozing inhibition of the formed linear discoloration was investigated by method. In the second durability test, the adhesive sheet having the linearly discolored portion formed in the adhesive layer was heat-treated at 65° C. and a relative humidity of 90% for 120 hours. The line width W1 of the linear discolored part before the second durability test, the line width W3 of the linear discolored part after the second durability test, and the change from the line width W1 to the line width W3 (｜W3－W1｜ ), and the rate of change (W3/W1) of the line width W3 relative to the line width W1 are shown in Table 1. Also, regarding the degree of change suppression of the discolored part, the situation of 0.90≦W3/W1≦1.2 was evaluated as "excellent", and the situation of 0.65≦W3/W1<0.9 or 1.2<W3/W1≦1.6 was evaluated as "good", The case where 0.50≦W3/W1<0.65 or 1.6<W3/W1≦2.0 was evaluated as "possible", and the case where W3/W1<0.50 or 2.0<W3/W1 was satisfied was evaluated as "impossible". The evaluation results are also shown in Table 1.

Regarding the amount of change (|W2-W1|) and rate of change (W2/W1) of the line width of the linearly discolored portion after the first durability test, the adhesive sheets of Examples 1 to 7 were smaller than those of Comparative Examples 1 to 3. Each adhesive sheet. W1 and W2 of each adhesive sheet of Examples 1-7 satisfy 0.5≦W2/W1≦1.6. Regarding the amount of change (|W3－W1|) and rate of change (W3/W1) of the line width of the linearly discolored part after the second durability test, the adhesive sheets of Examples 1 to 7 were also smaller than those of Comparative Examples 1 to 7. 3 each adhesive sheet. W1 and W3 of the adhesive sheets of Examples 1 to 7 satisfy 0.5≦W3/W1≦1.6. That is, each adhesive sheet of Examples 1-7 compared with each adhesive sheet of Comparative Examples 1-3, the change (deterioration) of the discoloration part of an adhesive layer was suppressed.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 polymer composition Polymer P ₁ Polymer P ₂ Polymer P ₃ Polymer P ₄ Polymer P ₅ Styrene 28.5(HS) - - - - MMA - 20(HS) - - - 4HBA 1.5(HS) 5(HS) 1.5(HS) 1.5(HS) 1.5(HS) CTFA - - 28.5(HS) 14.25(HS) 8.25(HS) IBXA - - - 14.25(HS) 20.25(HS) 2EHA 70(SS) 75(SS) 70(SS) 70(SS) 70(SS) Chromogenic compounds ( leuco pigments ) 2 2 2 2 2 Photoacid Generator (SP-056) 7 7 7 7 7 Crosslinking agent ( isocyanate crosslinking agent ) 0.25 0.25 0.25 0.25 0.25 Cross-linking catalyst ( dibutyltin dilaurate ) 0.01 0.01 0.01 0.01 0.01 Cross-linking inhibitor ( acetyl acetone ) 3 3 3 3 3 Hard block Tg( ℃ ) 90.6 105 23.3 52.2 66.1 Haze of adhesive layer (%) Before UV irradiation 1.0 2.7 1.0 1.0 2.9 After UV irradiation 1.0 2.2 1.0 1.0 2.2 The first durability test (85 ℃ , 120 h) W1(μm) 360.0 291.1 364.2 288.9 604.5 W2(μm) 342.2 300.0 436.5 356.0 617.8 |W2 － W1| 17.8 8.9 72.3 67.1 13.3 W2/W1 0.95 1.03 1.20 1.23 1.02 Evaluation excellent excellent excellent good excellent The second durability test (65 ℃ , 90%RH, 120 h) W1(μm) 302.2 240.0 329.6 311.1 635.6 W3(μm) 302.2 266.7 413.3 307.0 666.7 |W3 － W1| 0 26.7 83.7 4.1 31.1 W3/W1 1.00 1.11 1.25 0.98 1.05 Evaluation excellent excellent good excellent excellent

[Table 2] Example 6 Example 7 Comparative example 1 Comparative example 2 Comparative example 3 polymer composition Polymer P ₆ Polymer P ₇ Polymer P ₈ Polymer P ₉ Polymer P ₁₀ MMA - - 9 - - 4HBA 1.5(HS) - - 3.5(SS) 3.5(SS) MA 14.25(HS) - - - 30(HS) IBXA 14.25(HS) 14.55(HS) - - - HEA - - 13 - - NVP - - 15 - - PEA - - - 30(HS) - ACMO - 14.55(HS) - - - AAA - 0.9(HS) - - - 2EHA 70(SS) 70(SS) 63 66.5(SS) 66.5(SS) Chromogenic compounds ( leuco pigments ) 2 2 2 2 2 Photoacid Generator (SP-056) 7 7 7 7 7 Crosslinking agent ( isocyanate crosslinking agent ) 0.25 0.25 0.25 0.25 0.25 Cross-linking catalyst ( dibutyltin dilaurate ) 0.01 0.01 0.01 0.01 0.01 Cross-linking inhibitor ( acetyl acetone ) 3 3 3 3 3 Hard block Tg( ℃ ) 41.5 119.1 - 0.7 3.2 Haze of adhesive layer (%) Before UV irradiation 1.0 1.3 0.5 1.0 1.0 After UV irradiation 1.0 1.0 0.6 1.0 1.0 The first durability test (85 ℃ , 120 h) W1(μm) 356.1 458.4 340.0 258.2 347.0 W2(μm) 511.5 497.7 708.9 551.3 622.0 |W2 － W1| 156.4 39.3 368.9 293.1 275.0 W2/W1 1.44 1.09 2.09 2.14 1.79 Evaluation good excellent can't can't Can The second durability test (65 ℃ , 90%RH, 120 h) W1(μm) 493.4 565.1 360.0 284.5 364.3 W3(μm) 556.3 400.2 853.4 662.7 689.8 |W3 － W1| 62.9 164.9 493.4 378.2 325.5 W3/W1 1.13 0.71 2.37 2.33 1.89 Evaluation excellent good can't can't Can

10: Adhesive layer 11: Discoloration part 20: Substrate 31: 1st component 32: 2nd member L: peel film M1: Phase 1 M2: Phase 2 S: Adhesive sheet (color changeable adhesive sheet) Z: laminated body

Fig. 1 is a schematic cross-sectional view of an embodiment of the color-changing adhesive sheet of the present invention. Fig. 2 is a schematic diagram of an example of a microphase separation structure in an adhesive layer. Figure 2A shows a spherical structure, Figure 2B shows a cylindrical structure, Figure 2C shows a helical structure, and Figure 2D shows a layered structure. Fig. 3 is a schematic cross-sectional view of a variation example of the color-changing adhesive sheet of the present invention (when the color-changing adhesive sheet is a single-sided adhesive sheet with a base material). Fig. 4 shows an example of the method of using the color-changing adhesive sheet of the present invention. FIG. 4A shows a step of preparing a color-variable adhesive sheet and a member (adhered body), and FIG. 4B shows a step of bonding members to each other via a color-variable adhesive sheet. FIG. 4C shows the step of forming a discoloration part on the adhesive layer of the discoloration adhesive sheet. FIG. 5 is a TEM image of the adhesive layer of Example 1. FIG. FIG. 6 is a TEM image of the adhesive layer of Example 2. FIG. FIG. 7 is a TEM image of the adhesive layer of Example 4. FIG. Fig. 8 is a TEM image of the adhesive layer of Example 5. FIG. 9 is a TEM image of the adhesive layer of Comparative Example 1. FIG. FIG. 10 is a TEM image of the adhesive layer of Comparative Example 3.

10: Adhesive layer

L: peel film

S: Adhesive sheet (color changeable adhesive sheet)

Claims (10)

A color-changing adhesive sheet, which is provided with a color-changing adhesive layer, and The above-mentioned adhesive layer includes: a polymer component, which forms a microphase-separated structure including a first phase and a second phase; and a colorant, which can develop color by external stimulation; The above-mentioned coloring agent has compatibility with the above-mentioned first phase, and does not have compatibility with the above-mentioned second phase, The above-mentioned polymer component includes a polymer, and the above-mentioned polymer has a first segment forming the above-mentioned first phase and a second segment forming the above-mentioned second phase in the molecule, The first segment has a first glass transition temperature of 10°C to 120°C, and the second segment has a second glass transition temperature lower than the first glass transition temperature. The color-changing adhesive sheet according to claim 1, wherein the second glass transition temperature is 50°C or lower. The color-changing adhesive sheet according to claim 1, wherein the difference between the first glass transition temperature and the second glass transition temperature is not less than 40°C and not more than 200°C. The color-changing adhesive sheet according to claim 1, wherein the above-mentioned polymer is a block polymer, and the block polymer has a first polymer block as the above-mentioned first segment, and a second polymer block as the above-mentioned second segment. 2 polymer blocks. The color-changing adhesive sheet according to claim 1, wherein the above-mentioned polymer is a graft polymer, and the graft polymer has a polymer main chain as the above-mentioned second segment, and a polymer side as the above-mentioned first segment chain. The color-changing adhesive sheet according to claim 1, wherein the mass ratio of the second phase in the polymer component is greater than the mass ratio of the first phase. The color-changing adhesive sheet according to any one of claims 1 to 6, wherein the above-mentioned colorant is a compound that develops color by reacting with an acid, and The said adhesive layer further contains a photoacid generator. The color-changing adhesive sheet according to claim 7, wherein the photoacid generator is compatible with the first phase and not compatible with the second phase. The color-changing adhesive sheet according to any one of Claims 1 to 6, wherein the first color-changing width W1 of the color-changing region formed in the adhesive layer by linearly applying the external stimulus to the adhesive layer, And further, the second discoloration width W2 of the discoloration region after heat-treating the adhesive layer at 85° C. for 120 hours satisfies 0.5≦W2/W1≦1.6. The color-changing adhesive sheet according to any one of Claims 1 to 6, wherein the first color-changing width W1 of the color-changing region formed in the adhesive layer by linearly applying the external stimulus to the adhesive layer, And further, the third discoloration width W3 of the discoloration region after heat-treating the adhesive layer at 65° C. and a relative humidity of 90% for 120 hours satisfies 0.5≦W2/W1≦1.6.

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