JP2022079135A - Adhesive composition for flexible displays, adhesive material and adhesive sheet - Google Patents

Abstract

To provide an adhesive composition for flexible displays having excellent restorability.SOLUTION: An adhesive composition for flexible displays is used to form an adhesive layer 12 for bonding a first flexible sheet 14 to a second flexible sheet 16, the adhesive composition containing a (meth)acrylic copolymer having a first reactive group, and a crosslinker having a second reactive group to react with the first reactive group. An amount of the first reactive groups included in the (meth)acrylic copolymer is 0.002 mmol/g-0.4 mmol/g. A molar ratio of the second reactive groups included in the crosslinker and the first reactive groups included in the copolymer (molar amount of first reactive group/molar amount of second reactive group) is 1 or more. A molar ratio of the first reactive groups included in the copolymer to a blending amount of the crosslinker (molar amount of first reactive group/molar amount of crosslinker) is less than 12.0.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure-sensitive adhesive composition used for a flexible display, specifically, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive material used for bonding one flexible member and another flexible member.

In various displays and touch panels of televisions, mobile phones, smartphones, etc., adhesive materials are generally used for joining the members constituting these. The adhesive material is provided in the form of, for example, a pressure-sensitive adhesive sheet with a base material having an adhesive layer on a support base material or a base material-less pressure-sensitive adhesive sheet without a support base material, and the members are bonded to each other.

On the other hand, in recent years, flexible displays that are repeatedly bent and used in image display devices such as liquid crystal displays and organic electroluminescence (organic EL) display devices have attracted attention. Flexible displays include foldable foldable displays, rollable displays that can be rolled into a tubular shape, and the like, and are expected to be used for mobile terminals such as smartphones and tablet terminals, and stationary displays that can be stored.

In such a flexible display, as an adhesive material for laminating a flexible member constituting a member that is repeatedly bent and extended and another flexible member, for example, Patent Document 1 describes one surface and the other of the adhesive layer. Adhesive for repetitive bending devices in which the ratio of shear stress 60 seconds after 1000% displacement to the maximum shear stress when the surfaces are displaced 1000% in opposite directions and the gel fraction are controlled within a predetermined range. Is disclosed (see Patent Document 1 (Claim 1)).

Japanese Unexamined Patent Publication No. 2019-1084498

In the conventional flexible display having an adhesive layer, when the adhesive layer is repeatedly bent, the adhesive layer does not sufficiently recover from the bent state to the original state. Therefore, when the flexible display is repeatedly bent, there is a possibility that the interface between the adhesive layer and the flexible member at the bent portion may be lifted or peeled off, or the bent portion may appear wavy.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive material (adhesive layer) having excellent resilience.

The adhesive composition for a flexible display of the present invention, which has been able to solve the above problems, is an adhesive composition for a flexible display for bonding one flexible member constituting a flexible display to another flexible member. The pressure-sensitive adhesive composition contains a (meth) acrylic copolymer having a first reactive group and a cross-linking agent having a second reactive group that reacts with the first reactive group. ) The amount of the first reactive group possessed by the acrylic copolymer is 0.002 mmоl / g to 0.4 mmоl / g, and the second reactive group possessed by the cross-linking agent and the first reactive group possessed by the copolymer. The molar ratio with the group (molar amount of the first reactive group / molar amount of the second reactive group) is 1 or more, and the molar of the first reactive group possessed by the copolymer with respect to the blending amount of the cross-linking agent. The ratio (molar amount of the first reactive group / molar amount of the cross-linking agent) is less than 12.0.

By using the adhesive composition for a flexible display of the present invention, an adhesive material (adhesive layer) having excellent resilience can be formed. Therefore, by using the adhesive composition for a flexible display of the present invention, even if it is repeatedly bent, the interface between the adhesive layer and the flexible member at the bent portion does not float or peel off, and cracks, waviness, etc. occur. A flexible display that can suppress the occurrence of appearance defects can be manufactured.

It is sectional drawing of an example of the adhesive sheet of this invention. It is sectional drawing of an example of the flexible laminated member of this invention.

Hereinafter, an example of a preferred embodiment of the present invention will be described. However, the following embodiments are merely examples. The present invention is not limited to the following embodiments.

In the present invention, "(meth) acrylic" refers to "at least one of acrylic and methacrylic". "(Meta) acrylate" means "at least one of acrylate and methacrylate". "(Meta) acryloyl" means "at least one of acryloyl and methacryloyl". The "vinyl monomer" refers to a monomer having a carbon-carbon double bond in which radical polymerization is possible in the molecule. The "structural unit derived from a vinyl monomer" means a structural unit obtained by polymerizing a radically polymerizable carbon-carbon double bond of a vinyl monomer into a carbon-carbon single bond. The “structural unit derived from (meth) acrylate” refers to a structural unit obtained by polymerizing a radically polymerizable carbon-carbon double bond of (meth) acrylate into a carbon-carbon single bond. The "structural unit derived from the (meth) acrylic monomer" means a structural unit obtained by polymerizing a radically polymerizable carbon-carbon double bond of the (meth) acrylic monomer into a carbon-carbon single bond.

[Adhesive composition for flexible display]
The adhesive composition for a flexible display of the present invention (hereinafter, may be simply referred to as "adhesive composition") is a flexible display for bonding one flexible member constituting a flexible display to another flexible member. Adhesive composition for use. The pressure-sensitive adhesive composition contains (A) a (meth) acrylic copolymer having a first reactive group and (B) a cross-linking agent having a second reactive group that reacts with the first reactive group. do.

((A) (meth) acrylic copolymer)
The (meth) acrylic copolymer may be a copolymer having a structural unit derived from the (meth) acrylic monomer as a main component (50% by mass or more), and is a vinyl monomer other than the (meth) acrylic monomer. Can contain structural units derived from. The content of the structural unit derived from the (meth) acrylic monomer in the (A) copolymer is preferably 80% by mass or more, more preferably 90% by mass or more in 100% by mass of the entire copolymer. The copolymer (A) may be composed of only structural units derived from the (meth) acrylic monomer.

The (A) copolymer is preferably a (meth) acrylate-based copolymer. The (meth) acrylate-based copolymer may be a copolymer containing a structural unit derived from (meth) acrylate as a main component (50% by mass or more), and is derived from a vinyl monomer other than (meth) acrylate. Can contain structural units. The (meth) acrylate is an ester compound produced from (meth) acrylic acid and a compound having a hydroxy group. The content of the structural unit derived from the (meth) acrylate in the (A) copolymer is preferably 80% by mass or more, more preferably 90% by mass or more in 100% by mass of the entire copolymer.

The (A) copolymer has a first reactive group. The first reactive group is a functional group having high reactivity with the second reactive group of the (B) cross-linking agent described later. Examples of the functional group that can be the first reactive group include a functional group having reactivity. The first reactive group is preferably a hydroxy group and / or a carboxy group.

Examples of the combination of the first reactive group of the (A) copolymer and the second reactive group of the (B) cross-linking agent include the following combinations.
When the second reactive group of the (B) cross-linking agent is an isocyanate group, examples of the first reactive group include a hydroxy group.
When the second reactive group of the (B) cross-linking agent is an epoxy group, the first reactive group includes a carboxy group.

As a combination of the first reactive group of the (A) copolymer and the second reactive group of the (B) cross-linking agent, (1) the first reactive group is a hydroxy group and the second A combination in which the reactive group is an isocyanate group; (2) a combination in which the first reactive group is a carboxy group and the second reactive group is an epoxy group is preferable.

The amount of the first reactive group of the (A) copolymer is preferably 0.002 mmol / g or more, more preferably 0.006 mmol / g or more, still more preferably 0.01 mmol / g or more, and 0.4 mmol or more. It is preferably / g or less, more preferably 0.2 mmol / g or less, still more preferably 0.1 mmol / g or less. When the amount of the first reactive group is 0.002 mmol / g or more, the formed pressure-sensitive adhesive is appropriately crosslinked to exhibit a suitable restoration rate, and when it is 0.4 mmol / g or less, the formed pressure-sensitive adhesive is used. The distance between the cross-linking points is sufficiently long and the flexibility is excellent.

When the hydroxy group is the first reactive group, the copolymer (A) preferably has a carboxy group as a functional group other than the first reactive group. In this case, the carboxy group amount of the (A) copolymer is preferably 0.08 mmol / g or more, more preferably 0.16 mmol / g or more, still more preferably 0.32 mmol / g or more, and 1.3 mmol. It is preferably / g or less, more preferably 0.8 mmol / g or less, still more preferably 0.6 mmol / g or less.

When the carboxy group is the first reactive group, the copolymer (A) preferably has a group as a functional group other than the first reactive group. In this case, the amount of the carboxy group of the (A) copolymer is preferably 0.08 mmol / g or more, and preferably 1.3 mmol / g or less.

When the (A) copolymer has both a carboxy group and a hydroxy group, the molar ratio (carboxy group / hydroxy group) of the carboxy group and the hydroxy group per unit mass of the (A) copolymer is determined. 4 or more is preferable, 8 or more is more preferable, 16 or more is more preferable, 60 or less is preferable, 40 or less is more preferable, and 30 or less is further preferable. If the molar ratio (carboxy group / hydroxy group) is within the above range, the pressure-sensitive adhesive layer has high resilience and has a suitable balance between adhesive strength and flexibility.

The copolymer (A) has a first reactive group. That is, the copolymer (A) contains a structural unit (a-1) having a first reactive group in its structure. The structural unit (a-1) having the first reactive group may have only one kind or two or more kinds. The first reactive group is a structural unit derived from a (meth) acrylic monomer (preferably (meth) acrylate monomer and / or (meth) acrylic acid), and a structural unit derived from a vinyl monomer other than the (meth) acrylic monomer. You may have it in any of the above. That is, the structural unit (a-1) having the first reactive group is derived from the (meth) acrylic monomer having the first reactive group (preferably (meth) acrylate monomer and / or (meth) acrylic acid). Examples thereof include a structural unit to be used, or a structural unit derived from a vinyl monomer other than the (meth) acrylic monomer having a first reactive group.

The content of the structural unit (structural unit (a-1) having the first reactive group) derived from the vinyl monomer having the first reactive group in the (A) copolymer is 100 mass by mass of the entire copolymer. %, More preferably 0.03% by mass or more, more preferably 0.09% by mass or more, still more preferably 0.15% by mass or more, preferably 6% by mass or less, still more preferably 3% by mass or less. More preferably, it is 1.5% by mass or less. When the content of the structural unit (a-1) is within the above range, it is possible to form an adhesive material having an excellent balance between adhesion to an adherend and durability. The vinyl monomer having a first reactive group includes a (meth) acrylic monomer having a first reactive group and a vinyl monomer other than the (meth) acrylic monomer having a first reactive group.

The (meth) acrylic monomer includes (b1) a (meth) acrylic monomer having no functional group that can be a first reactive group, and (b2) a (meth) acrylic monomer having a functional group that can be a first reactive group. Can be mentioned. These monomers may be used alone or in combination of two or more. As the (b1) (meth) acrylic monomer, a (meth) acrylate monomer having no functional group that can be a (b1-1) first reactive group is preferable. Examples of the (b2) (meth) acrylic monomer include (b2-1) a (meth) acrylate monomer having a functional group that can be a first reactive group and (meth) acrylic acid.

As the (meth) acrylic monomer having no functional group that can be the (b1) first reactive group, a (meth) acrylate having a linear alkyl group, a (meth) acrylate having a branched chain alkyl group, and an alkoxy. It has a (meth) acrylate having a group, a (meth) acrylate having a polyalkylene glycol structural unit, a (meth) acrylate having an alicyclic hydrocarbon group, a (meth) acrylate having an aromatic group, and a tertiary amino group ( Examples thereof include (meth) acrylates and (meth) acrylamides. Among these, (meth) acrylate having a linear alkyl group, (meth) acrylate having a branched alkyl group, (meth) acrylate having an alicyclic hydrocarbon group, and (meth) acrylate having an aromatic group. And at least one selected from the group consisting of (meth) acrylamides is preferred.

As the (meth) acrylate having a linear alkyl group, a (meth) acrylate having a linear alkyl group having 1 to 20 carbon atoms is preferable, and carbon of the linear alkyl group is preferable. A (meth) acrylate having a linear alkyl group having a number of 1 to 10 is more preferable. Examples of the (meth) acrylate having a linear alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and n-hexyl (meth) acrylate. , N-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate and other (meth) acrylic acid linear alkyl Esther can be mentioned.

As the (meth) acrylate having a branched alkyl group, a (meth) acrylate having a branched alkyl group having 3 to 20 carbon atoms of the branched alkyl group is preferable, and the carbon of the branched alkyl group is preferable. A (meth) acrylate having a branched alkyl group having a number of 3 to 10 is preferable. Examples of the (meth) acrylate having a branched alkyl group include isopropyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, and isooctyl (meth) acrylate, 2 -Examples include (meth) acrylic acid branched chain alkyl esters such as ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and isodecyl (meth) acrylate.

Examples of the (meth) acrylate having an alkoxy group include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate.

Examples of the (meth) acrylate having a polyalkylene glycol structural unit include polyethylene glycol (polymerization degree = 2 to 10) methyl ether (meth) acrylate, polyethylene glycol (polymerization degree = 2 to 10) ethyl ether (meth) acrylate, and polyethylene. (Meta) acrylate having polyethylene glycol structural unit such as glycol (polymerization degree = 2 to 10) propyl ether (meth) acrylate, polyethylene glycol (polymerization degree = 2 to 10) phenyl ether (meth) acrylate; polypropylene glycol (polymerization degree) = 2-10) Methyl ether (meth) acrylate, polypropylene glycol (polymerization degree = 2-10) ethyl ether (meth) acrylate, polypropylene glycol (polymerization degree = 2-10) propyl ether (meth) acrylate, polypropylene glycol (polymerization) Degree = 2 to 10) Examples thereof include (meth) acrylate having a polypropylene glycol structural unit such as phenyl ether (meth) acrylate.

Examples of the (meth) acrylate having an alicyclic hydrocarbon group include (meth) acrylate having a cyclic alkyl group and (meth) acrylate having a polycyclic structure. The (meth) acrylate having a cyclic alkyl group is preferably a (meth) acrylate having a cyclic alkyl group having 6 to 12 carbon atoms. Examples of the cyclic alkyl group include a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group), and may have a chain portion. Specific examples of the (meth) acrylate having a cyclic alkyl group having a monocyclic structure include (meth) acrylic acid cyclic alkyl esters such as cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, and cyclododecyl (meth) acrylate. be able to.

The (meth) acrylate having a polycyclic structure is preferably a (meth) acrylate having a polycyclic structure having 6 to 12 carbon atoms. Examples of the polycyclic structure include a cyclic alkyl group having a crosslinked ring structure (for example, an adamantyl group, a norbonyl group, an isobornyl group), and may have a chain portion. Specific examples of the (meth) acrylate having a polycyclic structure include bornyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-adamantyl (meth) acrylate, and 2-methyl-2-. Adamanthyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, norbornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyloxyethyl (meth) Examples thereof include acrylate, dicyclopentenyloxyethyl (meth) acrylate and the like.

The (meth) acrylate having an aromatic group is preferably a (meth) acrylate having an aromatic group having 6 to 12 carbon atoms. Examples of the aromatic group include an aryl group and the like, and may have a chain portion such as an alkylaryl group, an araryl group, an aryloxyalkyl group and the like. Examples of the (meth) acrylate having an aromatic group include a compound in which an aryl group is directly bonded to a (meth) acryloyloxy group, a compound in which an aralkyl group is directly bonded to a (meth) acryloyloxy group, and a (meth) acryloyloxy group. Examples thereof include compounds in which an alkylaryl group is directly bonded. The aryl group preferably has 6 to 12 carbon atoms. The carbon number of the aralkyl group is preferably 6 to 12. The alkylaryl group preferably has 6 to 12 carbon atoms. Examples of the (meth) acrylate having an aromatic group include benzyl (meth) acrylate, phenyl (meth) acrylate, and phenoxyethyl (meth) acrylate.

Examples of the (meth) acrylate having a tertiary amino group include 2- (dimethylamino) ethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the (meth) acrylamides include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, (meth) acrylamide, and N-methyl (meth). Acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-octyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl ( Examples thereof include meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acryamide, 4- (meth) acryloylmorpholine and the like. The (meth) acrylamides are (meth) acrylic monomers, but are not included in the (meth) acrylate monomers.

Examples of the (meth) acrylic monomer having a functional group that can be the (b2) first reactive group include a (meth) acrylic monomer having a hydroxy group (preferably a (meth) acrylate monomer) and a (meth) acrylic having a carboxy group. Examples thereof include a monomer (preferably (meth) acrylic acid), a (meth) acrylic monomer having an epoxy group (preferably (meth) acrylate monomer), and the like. Among these, a (meth) acrylic monomer having a hydroxy group and / or a (meth) acrylic monomer having a carboxy group is preferable.

Examples of the (meth) acrylic monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6. Hydroxyalkyl (meth) acrylates such as -hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; (4-hydroxymethylcyclohexyl). Hydroxyalkylcycloalkane (meth) acrylates such as methyl (meth) acrylates; caprolactone adducts of hydroxyalkyl (meth) acrylates and the like can be mentioned. Among these, hydroxyalkyl (meth) acrylates are preferable, and (meth) acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are more preferable.

Examples of the (meth) acrylic monomer having a carboxy group include carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinate, and 2- (meth) acryloyloxyethyl maleate, 2. -A monomer obtained by reacting a (meth) acrylate having a hydroxy group such as (meth) acryloyloxyethyl phthalate with an acid anhydride such as maleic anhydride, succinic anhydride or phthalic anhydride, (meth) acrylic acid and the like can be mentioned. .. Among these, (meth) acrylic acid is preferable.

Examples of the (meth) acrylic acid ester having an epoxy group include glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate.

Examples of the vinyl monomer other than the (meth) acrylic monomer include (b3) a vinyl monomer other than the (meth) acrylic monomer having no functional group that can be a first reactive group, and (b4) a functional group that can be a first reactive group. Examples thereof include vinyl monomers other than (meth) acrylic monomers having a group. These monomers may be used alone or in combination of two or more.

Examples of the vinyl monomer other than the (meth) acrylic monomer having no functional group that can be the (b3) first reactive group include an aromatic vinyl monomer, a vinyl monomer containing a heterocycle, vinyl carboxylate, and a tertiary amino group. Examples thereof include vinyl monomers containing quaternary ammonium bases, vinyl amides, α-olefins, dienes, vinyl halide monomers and the like.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, 1-vinylnaphthalene and the like.
Examples of the vinyl monomer containing a heterocycle include 2-vinylthiophene, N-methyl-2-vinylpyrrole, 2-vinylpyridine, 4-vinylpyridine and the like.
Examples of the vinyl carboxylate include vinyl acetate, vinyl pivalate, vinyl benzoate and the like.
Examples of the vinyl monomer containing a tertiary amino group include N, N-dimethylallylamine and the like.
Examples of the vinyl monomer containing a quaternary ammonium base include N-methacryloylaminoethyl-N, N, N-dimethylbenzylammonium chloride and the like.
Examples of the vinyl amides include N-vinylformamide, N-vinylacetamide, 1-vinyl-2-pyrrolidone, N-vinyl-ε-captolactam and the like.
Examples of the α-olefin include 1-hexene, 1-octene, 1-decene and the like.
Examples of the diene include butadiene, isoprene, 4-methyl-1,4-hexadiene, 7-methyl-1,6-octadien and the like.
Examples of the vinyl halide monomer include vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, tetrafluoropropylene, vinylidene chloride, vinyl chloride, and 1-chloro-1-fluoro. Examples thereof include ethylene, 1,2-dichloro-1,2-difluoroethylene and the like.

Examples of the vinyl monomer other than the (meth) acrylic monomer having a functional group that can be the (b4) first reactive group include a vinyl monomer having a hydroxy group, a vinyl monomer having a carboxy group, and a vinyl monomer containing an epoxy group. Can be mentioned.

Examples of the vinyl monomer having a hydroxy group include p-hydroxystyrene and allyl alcohol.
Examples of the vinyl monomer having a carboxy group include crotonic acid, maleic acid, itaconic acid, citraconic acid, and cinnamon acid.
Examples of the vinyl monomer containing an epoxy group include 2-allyloxylane, glycidyl vinyl ether, and 3,4-epoxycyclohexylvinyl ether.

The copolymer (A) may be any of a random copolymer, a block copolymer, and a graft copolymer, and is preferably a random copolymer.

The weight average molecular weight (Mw) of the copolymer (A) is preferably 300,000 or more, more preferably 600,000 or more, further preferably 900,000 or more, 2.5 million or less, and even more preferably 2 million or less. , More preferably 1.8 million or less. When the Mw of the copolymer (A) is 300,000 or more, the cohesive force is increased and the heat resistance of the formed pressure-sensitive adhesive is improved, and when it is 2.5 million or less, the coating workability of the pressure-sensitive adhesive composition is better. It becomes. The method for measuring the weight average molecular weight (Mw) will be described later.

The molecular weight distribution (PDI) of the (A) copolymer is less than 3.0, preferably less than 2.5, more preferably less than 2.2, and even more preferably less than 1.8. The smaller the PDI, the narrower the width of the molecular weight distribution, and the copolymer has the same molecular weight. When the value is 1.0, the width of the molecular weight distribution is the narrowest. When the PDI is less than 3.0, a pressure-sensitive adhesive having a small molecular weight or a large molecular weight is low as compared with the molecular weight of the designed copolymer, and a pressure-sensitive adhesive having excellent bending resistance can be obtained. In the present invention, the molecular weight distribution (PDI) is a value calculated by (weight average molecular weight (Mw)) / (number average molecular weight (Mn)), and a method for measuring Mw and Mn will be described later.

The glass transition temperature (Tg) of the (A) copolymer is preferably −70 ° C. or higher, more preferably −60 ° C. or higher, preferably 0 ° C. or lower, more preferably −10 ° C. or lower, still more preferably −10 ° C. or lower. It is -20 ° C or lower. When Tg is −70 ° C. or higher, sufficient cohesive force is given to the adhesive material, the durability of the formed adhesive material is improved, and when Tg is 0 ° C. or lower, the adhesiveness of the formed adhesive material to the adherend is improved. It becomes high, peeling under low temperature is suppressed, and durability is improved.

The Tg of the copolymer (A) is a value calculated by the following FOX formula (formula (1)). In formula (1), Tg indicates the glass transition temperature (° C.) of the copolymer. Tgi indicates the glass transition temperature (° C.) when the vinyl monomer i forms a homopolymer. Wi indicates the mass ratio of the vinyl monomer i in all the vinyl monomers forming the copolymer, and ΣWi = 1. i is a natural number from 1 to n.

Table 1 shows the glass transition temperatures of typical homopolymers.

The copolymer (A) is produced by radically polymerizing a vinyl monomer by a living radical polymerization method. The living radical polymerization method maintains the convenience and versatility of the conventional radical polymerization method, but is less likely to cause a termination reaction or chain transfer, and grows without being hindered by a side reaction that deactivates the growth end. Precise control and production of polymers with uniform composition are easy. Therefore, in the copolymer produced by the living radical polymerization method, the reactive functional groups are uniformly distributed in each molecular chain. Therefore, if a copolymer produced by the living radical polymerization method is used, the crosslink point density in the pressure-sensitive adhesive becomes uniform as a whole.

In the living radical polymerization method, a random copolymer can be obtained by using a mixture of each monomer (vinyl monomer) constituting the (A) copolymer. Further, it is also possible to obtain a block copolymer by sequentially reacting vinyl monomers constituting the copolymer.

The living radical polymerization method includes a method using a transition metal catalyst (ATRP method); a method using a sulfur-based reversible chain transfer agent (RAFT method); and an organic tellurium compound, depending on the method for stabilizing the polymerization growth end. There are methods such as the method used (TERP method). Among these methods, it is preferable to use the TERP method from the viewpoint of the variety of monomers that can be used, the control of the molecular weight in the polymer region, the uniform composition, or the coloring.

The TERP method is a method of polymerizing a radically polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent. For example, International Publication No. 2004/14848, International Publication No. 2004/14962, International Publication No. The method described in 2004/072126 and 2004/096870.

Specific polymerization methods of the TERP method include the following (a) to (d).
(A) A method for polymerizing a vinyl monomer using an organic tellurium compound represented by the formula (1).
(B) A method for polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (1) and an azo-based polymerization initiator.
(C) A method for polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (1) and an organic diterlide compound represented by the formula (2).
(D) A method for polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (1), an azo-based polymerization initiator and an organic diterlide compound represented by the formula (2).

［式（１）において、Ｒ¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基である。Ｒ²およびＲ³は、それぞれ独立に、水素原子または炭素数１～８のアルキル基である。Ｒ⁴は、炭素数１～８のアルキル基、アリール基、置換アリール基、芳香族ヘテロ環基、アルコキシ基、アシル基、アミド基、オキシカルボニル基、シアノ基、アリル基またはプロパルギル基である。
式（２）において、Ｒ¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基である。］

[In the formula (1), R ¹ is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group. R ² and R ³ are independently hydrogen atoms or alkyl groups having 1 to 8 carbon atoms. R ⁴ is an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group or a propargyl group.
In formula (2), R ¹ is an alkyl group, an aryl group or an aromatic heterocyclic group having 1 to 8 carbon atoms. ]

The organic tellurium compound represented by the formula (1) is specifically ethyl-2-methyl-2-n-butylteranyl-propionate, ethyl-2-n-butylteranyl-propionate, (2-hydroxyethyl) -2-. Examples thereof include the organic tellurium compounds described in International Publication No. 2004/14848, International Publication No. 2004/14962, International Publication No. 2004/072126, and International Publication No. 2004/096870, such as methyl-methylteranyl-propionate. Specific examples of the organic diterlide compound represented by the formula (2) include dimethyl diterlide and dibutyl diterlide. The azo-based polymerization initiator can be used without particular limitation as long as it is an azo-based polymerization initiator used in ordinary radical polymerization. For example, 2,2'-azobis (isobutyronitrile) (AIBN), 2 , 2'-azobis (2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis (1-cyclohexanecarbonitrile) (ACHN), 2,2'-azobis (4-methoxy-2,4- Dimethylvaleronitrile) (V-70) and the like can be mentioned.

The polymerization step is a container substituted with an inert gas, and the vinyl monomer and the organic tellurium compound of the formula (1) are further azo-based for the purpose of promoting a reaction depending on the type of the vinyl monomer, controlling the molecular weight and the molecular weight distribution, and the like. The polymerization initiator and / or the organic diterlide compound of the formula (2) are mixed. At this time, examples of the inert gas include nitrogen, argon, and helium. Argon and nitrogen are preferable. The amount of the vinyl monomer used in the above (a), (b), (c) and (d) may be appropriately adjusted according to the physical characteristics of the target copolymer.

The polymerization reaction can be carried out without a solvent, but the mixture may be carried out by stirring using an aprotic solvent or a protic solvent generally used in radical polymerization. Examples of the aprotic solvent that can be used include anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, tetrahydrofuran (THF) and the like. Examples of the protonic solvent include water, methanol, 1-methoxy-2-propanol and the like. The solvent may be used alone or in combination of two or more. The amount of the solvent used may be appropriately adjusted, and for example, 0.01 ml to 50 ml is preferable with respect to 1 g of the vinyl monomer. The reaction temperature and reaction time may be appropriately adjusted depending on the molecular weight or molecular weight distribution of the obtained copolymer, but usually, the mixture is stirred at 0 ° C to 150 ° C for 1 minute to 100 hours. After the completion of the polymerization reaction, the solvent used, the residual vinyl monomer, and the like can be removed from the obtained reaction mixture by ordinary separation and purification means to separate the desired copolymer.

The growth end of the copolymer obtained by the polymerization reaction is in the form of —TeR ¹ (in the formula, R ¹ is the same as above) derived from the tellurium compound, and is inactivated by an operation in air after the completion of the polymerization reaction. However, the tellurium atom may remain. Since the copolymer in which the tellurium atom remains at the terminal is colored or has poor thermal stability, it is preferable to remove the tellurium atom. Examples of the method for removing the tellurium atom include a radical reduction method; a method of adsorbing with activated carbon or the like; a method of adsorbing a metal with an ion exchange resin or the like, and these methods can also be used in combination. The other end of the copolymer obtained by the polymerization reaction (the end opposite to the growth end) is -CR ² R ³ R ⁴ derived from the tellurium compound (in the formula, R ² , R ³ and R ⁴ are of the formula. (1) It is the same as R ² , R ³ and R ⁴ in).

((B) Crosslinking agent)
The pressure-sensitive adhesive composition contains (B) a cross-linking agent. The (B) cross-linking agent is a compound having two or more second reactive groups in one molecule that react with the first reactive group of the above-mentioned (A) copolymer. The (B) cross-linking agent is not particularly limited, and examples thereof include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, a metal chelate-type cross-linking agent, a melamine resin-based cross-linking agent, and a urea resin-based cross-linking agent. .. Among these, isocyanate-based cross-linking agents and epoxy-based cross-linking agents are preferable. In particular, an isocyanate-based cross-linking agent is more preferable because the restoration rate of the formed pressure-sensitive adhesive is improved.

The number of the second reactive groups contained in one molecule of the (B) cross-linking agent is 2 or more, preferably 6 or less, more preferably 4 or less, still more preferably 3 or less. That is, the (B) cross-linking agent is a bifunctional cross-linking agent having two second reactive groups in one molecule or a trifunctional cross-linking agent having three second reactive groups in one molecule. More preferred. (B) If the cross-linking agent is bifunctional or trifunctional, the cross-linking points are evenly distributed in the pressure-sensitive adhesive, and the average distance between the cross-linking points becomes long. Therefore, the obtained adhesive material has a low initial stress and exhibits a high restoration rate. The molecular weight of the (B) cross-linking agent is preferably 200 or more, more preferably 300 or more, further preferably 400 or more, preferably 1500 or less, still more preferably 1000 or less, still more preferably 700 or less.

The content of the second reactive group of the cross-linking agent (B) is preferably 1.5 mmol / g or more, more preferably 3 mmol / g or more, still more preferably 3.7 mmol / g or more, and 8 mmol / g or less. It is preferable, more preferably 6 mmol / g or less. If the content of the second reactive group of the cross-linking agent (B) is in this range, the valence of the cross-linking agent (B) becomes low, the cross-linking points are evenly distributed in the adhesive material, and the average distance between the cross-linking points becomes. become longer. Therefore, the obtained adhesive material has a low initial stress and exhibits a high restoration rate.

(Isocyanate-based cross-linking agent)
The isocyanate-based cross-linking agent is a compound having two or more isocyanate groups (including an isocyanate regenerated functional group in which the isocyanate group is temporarily protected by a blocking agent or quantification) as a second reactive group in one molecule. be. The isocyanate-based cross-linking agent may be used alone or in combination of two or more.

Examples of the isocyanate-based cross-linking agent include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, additives between these and various polyols, isocyanurate bonds, burette bonds, allophanate bonds, and the like. Examples thereof include polyisocyanates. Among these, a compound having two isocyanate groups (including an isocyanate regenerated functional group in which the isocyanate group is temporarily protected by a blocking agent or quantification) in one molecule (bifunctional isocyanate-based cross-linking agent), or A compound having three isocyanate groups (including an isocyanate regenerated functional group in which the isocyanate group is temporarily protected by a blocking agent or quantification) in one molecule (trifunctional isocyanate-based cross-linking agent) is preferable. (B) If the cross-linking agent is a bifunctional isocyanate-based cross-linking agent or a trifunctional isocyanate-based cross-linking agent, the cross-linking points are evenly distributed in the pressure-sensitive adhesive, and the distance between the average cross-linking points becomes long. Therefore, the obtained adhesive material has a low initial stress and exhibits a high restoration rate.

Examples of the bifunctional isocyanate-based cross-linking agent include diisocyanate compounds such as aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, and aromatic diisocyanate compounds, and adducts of these diisocyanate compounds and diol compounds can also be used. The diisocyanate compound has a general formula “O = C = N—X—N = C = O” (X is a divalent aliphatic group, a divalent alicyclic group, a divalent aromatic group, or the like. It is a compound represented by.). The diol compound is a compound represented by the general formula "HO-Y-OH" (Y is a divalent aliphatic group, a divalent alicyclic group, a divalent aromatic group, etc.). ..

Examples of the aliphatic diisocyanate compound include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, 2,2,4-. Examples thereof include trimethyl-1,6-hexamethylene diisocyanate, among which an aliphatic diisocyanate compound having 4 to 30 carbon atoms is preferable, and an aliphatic diisocyanate compound having 4 to 10 carbon atoms is more preferable.

Examples of the alicyclic diisocyanate compound include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, and the like, among which the number of carbon atoms is 7. ~ 30 alicyclic diisocyanate compounds are preferred.

Examples of the aromatic diisocyanate compound include phenylenediocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate, and aromatic diisocyanate compounds having 8 to 30 carbon atoms are preferable.

Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2-ethyl-2. -Alphatic diol compounds such as butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,6 hexanediol, polyethylene glycol and polypropylene glycol can be mentioned, and among these, the number of carbon atoms is 3 to 10. Aliphatic diol compounds are preferred.

Examples of the trifunctional isocyanate-based cross-linking agent include an adduct body of the diisocyanate compound, a burette body of the diisocyanate compound, and an isocyanurate body of the diisocyanate compound (cyclic trimer of the diisocyanate compounds).

The isocyanate-based cross-linking agent preferably does not have an aromatic ring. In particular, the isocyanate-based cross-linking agent includes a bifunctional isocyanate-based cross-linking agent selected from the group consisting of an aliphatic diisocyanate compound and an adduct of an aliphatic diisocyanate compound and an aliphatic diol compound, and an aliphatic diisocyanate compound. A trifunctional isocyanate-based cross-linking agent selected from the group consisting of an adduct, a burette of an aliphatic diisocyanate compound, and an isocyanurate of an aliphatic diisocyanate compound is preferable.

(Epoxy cross-linking agent)
The epoxy-based cross-linking agent refers to a compound having two or more epoxy groups in one molecule as a second reactive group. The epoxy-based cross-linking agent may be used alone or in combination of two or more.

Examples of the epoxy-based cross-linking agent include bisphenol A, epichlorohydrin-type epoxy-based resin, ethylene glycidyl ether, N, N, N', N'-tetraglycidyl-m-xylene diamine, diglycidyl aniline, diamine glycidyl amine, 1 , 3-Bis (N, N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether. , Adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether and the like.

Examples of the epoxy-based cross-linking agent include a compound having two epoxy groups in one molecule (bifunctional epoxy-based cross-linking agent) and a compound having three epoxy groups in one molecule (trifunctional epoxy-based cross-linking agent). preferable. (B) If the cross-linking agent is a bifunctional epoxy-based cross-linking agent or a tri-functional epoxy-based cross-linking agent, the cross-linking points are evenly distributed in the pressure-sensitive adhesive, and the distance between the average cross-linking points becomes long. Therefore, the obtained adhesive material has a low initial stress and exhibits a high restoration rate.

The pressure-sensitive adhesive composition preferably contains only an isocyanate-based cross-linking agent as (B) a cross-linking agent, and particularly, as (B) a cross-linking agent, a bifunctional isocyanate-based cross-linking agent having two isocyanate groups in one molecule, or It is preferable to contain only a trifunctional isocyanate-based cross-linking agent having three isocyanate groups in one molecule.

The content of the cross-linking agent (B) in the pressure-sensitive adhesive composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and 0.2 parts by mass with respect to 100 parts by mass of the copolymer (A). It is preferably 0 parts by mass or less, and more preferably 0.15 parts by mass or less. When the content of the cross-linking agent (B) is within the above range, the adhesive strength and the restoration rate are in the preferable range.

The molar ratio of the second reactive group of the (B) cross-linking agent to the first reactive group of the (A) copolymer (molar amount of the first reactive group / molar amount of the second reactive group). ) Is 1 or more, preferably 2 or more, more preferably 3 or more, preferably 15 or less, more preferably 10 or less, still more preferably 5 or less. When the molar ratio is 1 or more, the cross-linking agent reacts without excess or deficiency, no surplus is generated in the second reactive group, and a high restoration rate is exhibited. When the molar ratio is 15 or less, the reaction proceeds sufficiently and the restoration rate is high. Is expressed.

The molar ratio of the first reactive group (molar amount of the first reactive group / molar amount of the cross-linking agent) of the (A) copolymer to the compounding amount (molar amount) of the (B) cross-linking agent is 12. It is less than 9.0, more preferably 11.0 or less, still more preferably 8.0 or less. If the molar ratio is less than 12.0, the restoration rate decreases. The molar ratio (molar amount of the first reactive group / molar amount of the cross-linking agent) is preferably 2 or more, more preferably 4 or more.

(Other additives)
In addition to the (A) copolymer and (B) cross-linking agent, other additives can be blended and used in the pressure-sensitive adhesive composition. Other additives include cross-linking accelerators, cross-linking retarders, tackifiers, plasticizers, softeners, release aids, silane coupling agents, dyes, pigments, dyes, fluorescent whitening agents, and charging. Inhibitors, wetting agents, surfactants, thickeners, fungicides, preservatives, oxygen absorbers, UV absorbers, antioxidants, near-infrared absorbers, water-soluble quenchers, fragrances, metal deactivators, Examples include nucleating agents, alkylating agents, flame retardants, lubricants, processing aids and the like. These are appropriately selected and blended according to the use and purpose of use of the adhesive material.

(Crosslink accelerator)
If necessary, a cross-linking accelerator can be added to the pressure-sensitive adhesive composition for use. Examples of the cross-linking accelerator include organotin compounds and metal chelate compounds. The cross-linking accelerator may be used alone or in combination of two or more.

Examples of the organotin compound include dibutyltin dilaurate, dioctiolstindilaurylate, and dibutyltin dioctylate. The metal chelate compound is a complex in which a ligand having two or more coordinate atoms forms a ring and is bonded to a central metal.

The content of the cross-linking accelerator in the pressure-sensitive adhesive composition is preferably 0.01 part by mass or more, more preferably 0.02 part by mass or more, and further preferably 0. It is 04 parts by mass or more, preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and further preferably 0.3 parts by mass or less. By setting the content of the cross-linking accelerator in the above range, it is possible to obtain an excellent cross-linking promoting effect.

(Crosslink retarder)
If necessary, a cross-linking retarder can be added to the pressure-sensitive adhesive composition for use. The cross-linking retarder is a compound capable of suppressing an excessive increase in viscosity of the pressure-sensitive adhesive composition by blocking the functional groups of the cross-linking agent in the pressure-sensitive adhesive composition containing the cross-linking agent. The type of cross-linking retarder is not particularly limited, but β-diketones such as acetylacetoacetic acid, hexane-2,4-dione, heptane-2,4-dione, octane-2,4-dione; Β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, octyl acetoacetic acid, oleyl acetoacetate, lauryl acetoacetic acid, stearyl acetoacetate; benzoylacetone and the like can be used. As the cross-linking retarder, those capable of acting as a chelating agent are preferable, and β-diketones and β-ketoesters are preferable.

The content of the cross-linking retarder that can be blended in the pressure-sensitive adhesive composition is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, and further preferably 0.2 part by mass or more with respect to 100 parts by mass of the (A) copolymer. It is preferably 0.5 parts by mass or more, preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 1.5 parts by mass or less. By adjusting the content of the cross-linking retarder to the above range, after the (B) cross-linking agent is blended in the pressure-sensitive adhesive composition, excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition are suppressed, and the pressure-sensitive adhesive composition is used. Storage stability (pot life) can be extended.

(Adhesive-imparting resin)
If necessary, the pressure-sensitive adhesive composition may be blended with a pressure-sensitive adhesive resin other than the copolymer (A) and used. The tackifier resin is not particularly limited, and examples thereof include a rosin-based tackifier resin, a terpene-based tackifier resin, a phenol-based tackifier resin, and a hydrocarbon-based tackifier resin.

Examples of the rosin-based tackifier resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, and modified rosins (polymerization) obtained by polymerizing, disproportionating, or hydrogenating these unmodified rosins. Examples include rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, partially hydrogenated rosins, other chemically modified rosins, etc.), as well as various rosin derivatives.

The rosin derivative is, for example, a rosin phenol-based resin obtained by adding phenol to rosins (unmodified rosin, modified rosin) with an acid catalyst and thermally polymerizing the rosin. Ester compounds (unmodified rosin esters) and modified rosin ester compounds in which modified rosins are esterified with alcohols (polymerized rosin esters, stabilized rosin esters, disproportionated rosin esters, fully hydrogenated rosin esters, partially hydrogenated rosins. Esters, etc.) and other rosin ester-based resins; unsaturated fatty acid-modified rosin-based resins obtained by modifying unmodified rosin or modified rosin with unsaturated fatty acids; unsaturated fatty acid-modified rosin-based resins obtained by modifying rosin ester-based resins with unsaturated fatty acids. A rosin alcohol-based resin obtained by reducing a carboxyl group in an unmodified rosin, a modified rosin, an unsaturated fatty acid-modified rosin-based resin or an unsaturated fatty acid-modified rosin ester-based resin; Examples include metal salts of rosin ester-based resins).

Examples of the terpene-based tackifier resin include terpene-based resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer, and modification of these terpene-based resins (phenol modification, aromatic modification, hydrogenation modification, etc.). Examples thereof include modified terpene-based resins (for example, terpene phenol-based resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, hydrogenated terpene-based resins) that have been modified by hydrocarbons (etc.).

Examples of the phenol-based tackifier resin include a condensate of various phenols (eg, phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin) and formaldehyde (eg, alkylphenol-based resin, xyleneformaldehyde-based resin). Resin), resole obtained by addition-reacting the phenols and formaldehyde with an alkali catalyst, novolak obtained by subjecting the phenols and formaldehyde to a condensation reaction with an acid catalyst, and the like.

Examples of the hydrocarbon-based tackifier resin (petroleum-based tackifier resin) include aliphatic hydrocarbon resins [olefins having 4 to 5 carbon atoms and dienes (olefins such as butene-1, isobutylene, and pentene-1; butadiene, Polymers of aliphatic hydrocarbons such as 1,3-pentadiene and diene such as isoprene)], aliphatic cyclic hydrocarbon resins [so-called "C4 petroleum distillate" and "C5 petroleum distillate" are cyclized. Alicyclic hydrocarbon-based resins that have been embodied and then polymerized, polymers of cyclic diene compounds (cyclopentadiene, dicyclopentadiene, etilidennorbornene, dipentene, etc.) or their hydrogenated additives, the following aromatic hydrocarbon resins, and Alicyclic hydrocarbon-based resin obtained by hydrogenating the aromatic ring of an aliphatic / aromatic petroleum resin], aromatic hydrocarbon resin [vinyl group-containing aromatic hydrocarbon having 8 to 10 carbon atoms (styrene) , Vinyl toluene, α-methylstyrene, inden, methylinden, etc.)], aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.), aliphatic / alicyclic petroleum resins, Examples thereof include hydrogenated hydrocarbon resins, kumaron-based resins, and kumaron-inden-based resins.

The content of the tackifier resin that can be blended in the pressure-sensitive adhesive composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass with respect to 100 parts by mass of the copolymer (A). It is 5 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less. By adjusting the content of the tackifier resin within the above range, sufficient adhesion to the adherend can be ensured.

(Silane coupling agent)
If necessary, a silane coupling agent can be blended and used in the pressure-sensitive adhesive composition. The silane coupling agent is not particularly limited, but for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and the like. Epyl group-containing silane coupling agent such as 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- Amino group-containing silane coupling agents such as triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3- Examples include (meth) acrylic group-containing silane coupling agents such as methacryloxypropyltriethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanoppropyltriethoxysilane.

The content of the silane coupling agent that can be blended in the pressure-sensitive adhesive composition is preferably 1 part by mass or less, more preferably 0.01 part by mass to 1 part by mass, based on 100 parts by mass of the (A) copolymer. More preferably, it is 0.02 part by mass to 0.6 part by mass. By adjusting the content of the silane coupling agent to the above range, it is possible to increase the water resistance at the interface when the pressure-sensitive adhesive is applied to a hydrophilic adherend such as glass.

(Manufacturing method of adhesive composition)
The pressure-sensitive adhesive composition can be produced by mixing the (A) copolymer, (B) cross-linking agent, and other additives used as necessary. The pressure-sensitive adhesive composition may contain a solvent derived from the production of the (A) copolymer, or a suitable solvent may be further added to dilute the pressure-sensitive adhesive composition so as to have a viscosity suitable for forming the pressure-sensitive adhesive layer. It may be a solution.

Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone. Etc.; Esters such as ethyl acetate and butyl acetate; Cellosolve-based solvents such as ethyl cellosolve; Glycol ether-based solvents such as propylene glycol monomethyl ether. One of these solvents may be used alone, or two or more of them may be mixed and used.

The amount of the solvent used may be appropriately adjusted so that the pressure-sensitive adhesive composition has a viscosity suitable for coating, and is not particularly limited. However, from the viewpoint of coatability, for example, 1% by mass to 90% by mass is preferable. , More preferably 10% by mass to 80% by mass, still more preferably 20% by mass to 70% by mass.

(Use of adhesive composition)
The use of the pressure-sensitive adhesive composition is preferably used for forming a flexible display that can be repeatedly bent and stretched, and a pressure-sensitive adhesive layer (adhesive material) used for a flexible display.

Examples of the flexible display that can be repeatedly bent and stretched include a foldable foldable display and a rollable display that can be rolled into a cylinder. Flexible displays are expected to be used in mobile terminals such as smartphones and tablet terminals, and stationary displays that can be stored.

[Adhesive material for flexible display]
The pressure-sensitive adhesive material for a flexible display of the present invention is a cured product of the pressure-sensitive adhesive composition. The adhesive material can be used as an adhesive material for a flexible display for bonding one flexible member constituting a flexible display to another flexible member.

[Adhesive sheet for flexible display]
The adhesive sheet for a flexible display of the present invention has an adhesive layer used for adhering one flexible member constituting a flexible display and another flexible member, and the flexible attached to at least one surface of the adhesive layer. A pressure-sensitive adhesive sheet for a flexible display having a sheet member, wherein the pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive material.

The structure of the adhesive sheet includes an adhesive layer and a first flexible sheet member attached to one surface of the adhesive layer; the adhesive layer is attached to one surface of the adhesive layer. An embodiment having a first flexible sheet member and a second flexible sheet member attached to the other surface of the adhesive layer can be mentioned.

FIG. 1 shows an example of the pressure-sensitive adhesive sheet of the present invention. The pressure-sensitive adhesive sheet 10 of FIG. 1 is composed of a pressure-sensitive adhesive layer 12, a first flexible sheet member 14 that sandwiches the pressure-sensitive adhesive layer 12, and a second flexible sheet member 16. The adhesive layer 12 is in contact with the releasable surfaces of the first flexible sheet member 14 and the second flexible sheet member 16.

(Adhesive layer)
The adhesive layer is formed from the adhesive material. The film thickness of the adhesive layer is preferably 2 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, from the viewpoint of sufficiently ensuring the adhesiveness with the adherend. The thickness of the adhesive layer is preferably 100 μm or less, more preferably 70 μm or less, still more preferably 50 μm or less, from the viewpoint of suppressing the protrusion of the adhesive layer.

(Flexible sheet member)
Examples of the flexible sheet member include a flexible base sheet and a release sheet. The base material sheet is a sheet member that supports the adhesive layer, and the sheet member may be a functional sheet member. Examples of the functional sheet member include a cover film, a barrier film, a polarizing film, a retardation film, an optical compensation film, a brightness improving film, a diffusion film, an antireflection film and the like. The release sheet protects the adhesive layer until the adhesive layer is attached to the adherend, and is peeled off from the adhesive layer before the adhesive layer is attached to the adherend.

Generally, "sheet" is a flat product that is thin by definition in JIS and whose thickness is generally small for length and width, and "film" is generally referred to as length and width. A thin, flat product with an extremely small thickness and an arbitrarily limited maximum thickness, which is usually supplied in the form of a roll (Japanese Industrial Standards JIS K6900). For example, in terms of thickness, in a narrow sense, a film having a thickness of 100 μm or more may be referred to as a sheet, and a film having a thickness of less than 100 μm may be referred to as a film. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish between the two in the present invention, even if the term "sheet" is used in the present invention, the term "film" is included and the term "film" is used. But it includes "sheets".

Examples of the flexible sheet member include a sheet made of a polymer material, a glass sheet, and the like. The thickness of the flexible sheet member is not particularly limited, but is preferably 2 μm to 500 μm, more preferably 2 μm to 200 μm, from the viewpoint of excellent handleability and the like.

Examples of the polymer material include polyimide resin; polyester resin such as polyethylene terephthalate resin and polyethylene naphthalate resin; polycarbonate resin; poly (meth) acrylate resin; polystyrene resin; polyamide resin; polyacrylonitrile resin; polypropylene resin, polyethylene resin, and poly. Examples thereof include polyolefin resins such as cycloolefin resins; polyphenylene sulfide resins; polyvinyl chloride resins; polyvinylidene chloride resins; polyvinyl alcohol resins and the like.

The flexible sheet member may be composed of a single layer composed of a layer containing one or more of the polymer materials, or a layer containing one or more of the polymer materials and the layer containing one or more of the polymer materials. It may be composed of two or more layers, such as a layer containing one kind or two or more kinds of polymer materials different from the layer.

The flexible sheet member is preferably a release sheet in which the surface in contact with the adhesive layer is subjected to a mold release treatment. Examples of the mold release agent used for the mold release treatment include silicone-based, fluorine-based, alkyd-based, unsaturated polyester-based, polyolefin-based, and wax-based mold release agents.

The adhesive sheet has a first flexible sheet member attached to one surface of the adhesive layer and a second flexible sheet member attached to the other surface of the adhesive layer, and the first flexible sheet member. The sheet member is a first release sheet, the second flexible sheet member is a second release sheet, and the first release sheet and the second release sheet are attached so that their respective release surfaces are in contact with the adhesive layer. Is preferable. When the adhesive layer is sandwiched between two release sheets, one release sheet should be a heavy release type release sheet with a large release force, and the other release sheet should be a light release type release sheet with a small release force. Is preferable.

(Manufacturing of adhesive sheet)
The pressure-sensitive adhesive sheet can be produced, for example, by applying the above-mentioned pressure-sensitive adhesive composition onto a flexible sheet member and, if necessary, curing it by a dry heat treatment to form a pressure-sensitive adhesive layer.

For coating the adhesive composition, for example, reverse gravure coating method, direct gravure coating method, die coating method, bar coating method, wire bar coating method, roll coating method, spin coating method, dip coating method, spray coating method, knife. Various coating methods such as a coating method and a kiss coating method, and various printing methods such as an inkjet method, offset printing, screen printing, and flexographic printing can be adopted. Further, before applying the pressure-sensitive adhesive composition, the surface of the release sheet may be subjected to surface treatment such as corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

The drying and curing steps are not particularly limited as long as the solvent and the like used in the pressure-sensitive adhesive composition can be removed and cured, but the drying and curing steps are preferably performed at a temperature of 60 ° C. to 150 ° C. for about 20 seconds to 300 seconds. .. In particular, the drying temperature is preferably 100 ° C to 130 ° C.

When the first flexible sheet member is arranged on one surface of the adhesive layer and the second flexible sheet member is arranged on the other surface, the adhesive composition is applied to the first flexible sheet member, and the adhesive layer is applied on the first flexible sheet member. After forming the above, the second flexible sheet member may be attached to this adhesive layer. Furthermore, the adhesive layer may be cured if necessary. Examples of the curing conditions include, for example, about 3 to 7 days at 60 ° C.

[Flexible laminated member]
The flexible laminated member of the present invention is a flexible laminated member including a first flexible member, a second flexible member, and an adhesive layer for bonding the first flexible member and the second flexible member to each other. The adhesive layer is characterized by being made of the adhesive material. Since the adhesive layer of the flexible laminated member is formed of the adhesive material, even when the flexible laminated member is repeatedly bent, appearance defects such as the bent portion appearing to be wavy are suppressed.

FIG. 2 shows an example of the flexible laminated member of the present invention. The flexible laminated member 20 of FIG. 2 is an adhesive layer between the first flexible member 22, the second flexible member 24, the first flexible member 22 and the second flexible member 24, and the flexible members are bonded to each other. It is equipped with twelve.

As the configuration of the flexible laminated member, for example, both the first flexible member and the second flexible member are constituent members of the flexible device; the second flexible member is the flexible device, and the first flexible member is the flexible member. Examples thereof include a configuration in which the functional sheet member is attached to the flexible device. Examples of the flexible device include a foldable foldable display and a rollable display that can be rolled into a cylinder. Examples of the functional sheet member include a cover film, a barrier film, a polarizing film, a retardation film, an optical compensation film, a brightness improving film, a diffusion film, an antireflection film, a transparent conductive film, a metal mesh film, a cushion film and the like. Be done.

The first flexible member and the second flexible member are members that can be repeatedly bent or curved. Examples of the first flexible member and the second flexible member include a flexible substrate material, a functional sheet member, a display element (organic EL module, electronic paper module, etc.) and the like. It is preferable that at least one of the first flexible member and the second flexible member is a display element. The flexible laminated member can be used for a flexible display.

(Manufacturing method of flexible laminated member)
The method for manufacturing the flexible laminated member of the present invention is not particularly limited, and examples thereof include the following methods (1) to (4).

(1) The release sheet attached to one surface of the adhesive sheet is peeled off, the exposed adhesive layer is attached to the first flexible member, and then the release sheet attached to the other surface of the adhesive sheet. Is peeled off, and the exposed adhesive layer and the second flexible member are attached to each other to obtain a flexible laminated member.
(2) The pressure-sensitive adhesive composition is applied to one surface of the first flexible member and, if necessary, cured by dry heat treatment to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer has the releasability of a release sheet. Stick the surface. Then, a method of obtaining a flexible laminated member by peeling off the release sheet and attaching the exposed adhesive layer and the second flexible member.
(3) An adhesive composition is applied to one surface of the first flexible member and, if necessary, cured by a dry heat treatment to form an adhesive layer, and then the second flexible member is attached to the adhesive layer. , A method of obtaining a flexible laminated member.
(4) The adhesive composition is applied onto the releasable surface of the release sheet and, if necessary, cured by dry heat treatment to form an adhesive layer, and then the first flexible member is attached to the adhesive layer. do. Then, a method of obtaining a flexible laminated member by peeling off the release sheet and attaching the exposed adhesive layer and the second flexible member.

In any of the above cases (1) to (4), the order in which the first flexible member and the second flexible member are used may be exchanged.
For the formation of the adhesive layer, various coating methods and various printing methods similar to those for producing an adhesive sheet can be used, and the same applies to the drying and curing steps. In addition, it may be cured if necessary. Further, the release sheet used at the time of manufacturing the flexible laminated member may be the same as the release sheet used for the adhesive sheet.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented without changing the gist thereof. In addition, the polymerization rate of the block copolymer, the weight average molecular weight (Mw), the molecular weight distribution (PDI), the thickness of the adhesive layer, the gel fraction of the adhesive material, the initial stress and restoration rate when distorted by 400%, and the adhesive force. Was evaluated according to the following method.

The meanings of the abbreviations are as follows.
EHA: 2-Ethylhexyl acrylate LA: Lauryl acrylate AA: Acrylic acid HBA: 4-Hydroxybutyl acrylate BTEE: Ethyl-2-methyl-2-n-butylteranyl-propionate AIBN: Azobisisobutyronitrile AcOEt: Ethyl acetate

(Polymerization rate)
¹ H-NMR was measured (solvent: CDCl ₃ , internal standard: TMS) using a nuclear magnetic resonance (NMR) measuring device (manufactured by Bruker Biospin, model: AVANCE500 (frequency 500 MHz)). With respect to the obtained NMR spectrum, the integral ratio of the proton signal (3H) of the vinyl group derived from the monomer and the proton signal (1H) bonded to the α carbon of the carbonyl group derived from the polymer was obtained, and the polymerization rate of the monomer was calculated.

(Weight average molecular weight (Mw) and molecular weight distribution (PDI))
It was determined by gel permeation chromatography (GPC) using a high performance liquid chromatograph (manufactured by Tosoh Corporation, model HLC-8320GPC). Two TSKgel Super Multipore HZ-H (manufactured by Tosoh Corporation) were used as columns, a tetrahydrofuran solution was used for the mobile phase, and a differential refractometer was used for the detector. The measurement conditions were a column temperature of 40 ° C., a sample concentration of 0.5 mg / mL, a sample injection amount of 10 μm, and a flow rate of 0.6 mL / min. Polystyrene as a standard material (molecular weight 9,840,000, 5,480,000, 2,890,000, 1,090,000, 775,000, 427,000, 190,000, 96,400, 37,900, A calibration curve (calibration curve) was prepared using 10,200, 2,630,440), and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured. The molecular weight distribution (PDI = Mw / Mn) was calculated from this measured value.

(Adhesive layer thickness)
The thickness of the adhesive layer is measured by measuring the total thickness of the entire adhesive sheet using a thickness measuring machine (manufactured by Tester Sangyo Co., Ltd., "TH-104") and dividing the thickness of the release sheet from this total thickness. Asked.

(Gel fraction)
The mass W2 of the wire mesh (400 mesh) cut out with a width of 50 mm and a length of 120 mm was measured. An adhesive layer (adhesive material) of 80 mg to 120 mg was collected from the adhesive sheet, and the mass W1 was measured. A test piece was prepared by wrapping it in a wire mesh so that the adhesive material would not fall off. The test piece was placed in a glass bottle, 40 g of ethyl acetate was poured, and the mixture was shaken lightly and then allowed to stand at room temperature (25 ° C.) for 72 hours or more. After standing, the test piece was taken out from the glass bottle, left at room temperature for 12 hours or more, and further dried in a vacuum oven at 100 ° C. for 4 hours. The dried test piece was cooled to room temperature, the mass W3 was measured, and the gel fraction was calculated from the following formula.
Gel fraction (% by mass) = (W3-W2) / W1 × 100

(Initial stress and restoration rate when distorted by 400%)
Adhesive layers (adhesive materials) constituting the adhesive sheet were laminated by laminating them using a hand roller to prepare a laminated body having a thickness of 600 μmm. Using this laminate as a sample, using a viscoelasticity measuring device (ARES G2 manufactured by TA instruments), a strain relaxation test of 400% strain on a parallel plate with a diameter of 8 mm in a 25 ° C. atmosphere, and a stress relaxation test for 10 minutes, and a stress of 0 kPa. A 10-minute creep test was performed continuously. The initial stress was set to the value 0.1 seconds after the start of shear stress application in the stress relaxation test. Further, the restoration rate (%) was calculated from the strain after the creep test for 10 minutes based on the following formula. Then, the case where the restoration rate was 75% or more was evaluated as "◯", and the case where the restoration rate was less than 75% was evaluated as "x".
Restoration rate (%) = {(strain after creep test for 400-10 minutes) / 400} x 100

(Adhesive force)
One of the release sheets of the adhesive sheet is peeled off from the adhesive layer, and a corona-treated surface of a polyethylene terephthalate (PET) film (Toyobo Ester (registered trademark) film E5100: Toyobo, thickness 50 μm) is bonded to the adhesive layer surface to have a width of 25 mm. , A pressure-sensitive adhesive sheet with a base material was produced by cutting it into a size of 100 mm in length. With respect to this pressure-sensitive adhesive sheet with a base material, the adhesive strength against a polyimide film or glass as an adherend was measured according to the method of JIS Z 0237 (2009).
Specifically, the release sheet is peeled off from the adhesive layer, and the adhesive layer surface is made of a polyimide film (Kapton (registered trademark) 100 V: manufactured by Toray DuPont, thickness 25 μm) or white plate glass (S9111, manufactured by Matsunami Glass Industry Co., Ltd.). A 2 kg roller was reciprocated twice to a thickness of 1.0 to 1.2 mm) and crimped. Next, the adhesive strength of the adhesive layer was measured using a precision universal testing machine "AUTOGRAPH (registered trademark) AGS-1kNX, 50N load cell" manufactured by Shimadzu Corporation under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °.

<Manufacturing of copolymer>
(Synthesis Example 1: Copolymer No. A)
EHA (340.2 g), LA (240 g), AA (18 g), HBA (1.8 g), AIBN (26.1 mg), AcOEt (353.4 g) in a flask equipped with an argon gas introduction tube and a stirrer. Was charged, and after substitution with argon, BTEE (105 mg) was added, and the mixture was reacted at 60 ° C. for 24 hours for polymerization.

After completion of the reaction, AcOEt was added to the reaction solution to obtain the copolymer No. A copolymer solution containing A was obtained. The obtained copolymer No. The Mw of A was 1,624,000, the PDI was 1.77, and the solid content of the solution was 26.2% by mass. Table 2 shows the raw material monomers used, the organic tellurium compound, the azo-based polymerization initiator, the solvent, the reaction conditions, and the polymerization rate.

<Manufacturing of adhesive composition>
(Adhesive Composition No. 1)
The copolymer No. 1 obtained in Synthesis Example 1 Add 381 parts by mass of the solution of A (relative to 100 parts by mass of the copolymer component), 0.148 parts by mass of the cross-linking agent A (Duranate (registered trademark) D101), and 94.9 parts by mass of butyl acetate, and stir. Adhesive composition No. with a solid content of 21.0% by mass. I got 1. Adhesive Composition No. In No. 1, the first reactive group of the copolymer is a hydroxy group and the second reactive group of the cross-linking agent is an isocyanate group.

(Adhesive Composition No. 2-8)
Adhesive Composition No., except that the formulation was changed as shown in Table 3. In the same manner as in No. 1, the adhesive composition No. 2 to 8 were prepared. The blending amount of the cross-linking agent shown in Table 3 is the blending amount in terms of solid content. The solid content is a component other than the solvent. Adhesive Composition No. In Nos. 2 to 8, the first reactive group of the copolymer is a hydroxy group, and the second reactive group of the cross-linking agent is an isocyanate group.

<Making an adhesive sheet>
A film after drying using a baker-type applicator on the release surface of the first release sheet (PET film with a mold release treatment on the surface, Clean Sepa (registered trademark) HY-US20: manufactured by Higashiyama Film, thickness 75 μm). After applying the pressure-sensitive adhesive composition so as to have a thickness of 50 μm, drying was carried out at 60 ° C. for 3 minutes using a constant temperature dryer, followed by 150 ° C. for 3 minutes. Next, on the adhesive layer formed on the first release sheet, a second release sheet (PET film with a mold release treatment on the surface, Clean Sepa (registered trademark) HY-S10: manufactured by Higashiyama Film, thickness 38 μm) was applied. After the release surfaces were bonded together, aging was carried out at 60 for 3 days to prepare an adhesive layer sandwiched between two release sheets. Table 3 shows the evaluation results of the adhesive layer (adhesive material) formed from the adhesive composition to be written.

Crosslinking agent A: Duranate D101 (Asahi Kasei Corporation, isocyanate-based crosslinking agent (hexamethylene diisocyanate-1,6-hexanediol adduct, number of functional groups 2, solid content concentration 100% by mass, NCO amount 19.7% by mass))
Crosslinking agent B: Duranate TPA-100 (manufactured by Asahi Kasei Corporation, isocyanate-based crosslinking agent (isocyanurate form of hexamethylene diisocyanate, number of functional groups 3, solid content concentration 100% by mass, NCO amount 23.1% by mass))
Crosslinking agent C: Duranate MHG-80B (manufactured by Asahi Kasei Corporation, isocyanate-based crosslinking agent (isocyanurate form of hexamethylene diisocyanate, number of functional groups 6, solid content concentration 80% by mass, NCO amount 15.1% by mass))

Adhesive Composition No. In Nos. 1 to 3, the copolymer has a predetermined amount of the first reactive group, and the molar ratio (molar amount of the first reactive group of the copolymer / molar amount of the second reactive group of the cross-linking agent) and This is the case where the molar ratio (molar amount of the first reactive group of the copolymer / molar amount of the cross-linking agent) is within a predetermined range. These adhesive compositions No. The adhesive material formed from 1 to 3 had a practically acceptable adhesive force with respect to the polyimide film and glass, and had excellent resilience after being distorted by 400%.

Adhesive Composition No. In Nos. 4 to 8, the copolymer has a predetermined amount of the first reactive group, and the molar ratio (molar amount of the first reactive group of the copolymer / molar amount of the second reactive group of the cross-linking agent) is It is within a predetermined range, but the molar ratio (molar amount of the first reactive group of the copolymer / molar amount of the cross-linking agent) is 11.5 or more. These adhesive compositions No. The adhesive material formed from 4 to 8 had a practically acceptable adhesive strength with respect to the polyimide film and glass, but had poor resilience after being distorted by 400%.

10: Adhesive sheet 12: Adhesive layer 14: First flexible sheet member 16: Second flexible sheet member 20: Flexible laminated member 22: First flexible member 24: Second flexible member

Claims (13)

An adhesive composition for a flexible display for bonding one flexible member constituting a flexible display to another flexible member.
The pressure-sensitive adhesive composition contains a (meth) acrylic copolymer having a first reactive group and a cross-linking agent having a second reactive group that reacts with the first reactive group.
The first reactive group amount of the (meth) acrylic copolymer is 0.002 mmоl / g to 0.4 mmоl / g.
The molar ratio of the second reactive group of the cross-linking agent to the first reactive group of the copolymer (molar amount of the first reactive group / molar amount of the second reactive group) is 1 or more. ,
The copolymer is characterized in that the molar ratio of the first reactive group (molar amount of the first reactive group / molar amount of the cross-linking agent) to the compounding amount of the cross-linking agent is less than 12.0. Adhesive composition for flexible displays. Claim 1 in which the cross-linking agent contains a bifunctional cross-linking agent having two second reactive groups in one molecule or a trifunctional cross-linking agent having three second reactive groups in one molecule. The adhesive composition for a flexible display according to. The pressure-sensitive adhesive composition for a flexible display according to claim 1 or 2, wherein the cross-linking agent is an isocyanate-based cross-linking agent. The isocyanate-based cross-linking agent is an aliphatic diisocyanate compound, an adduct of an aliphatic diisocyanate compound and an aliphatic diol compound, an adduct of an aliphatic diisocyanate compound, a burette of an aliphatic diisocyanate compound, and an aliphatic diisocyanate compound. The adhesive composition for a flexible display according to claim 3, which is at least one selected from the group consisting of isocyanate compounds. The pressure-sensitive adhesive composition for a flexible display according to any one of claims 1 to 4, wherein the copolymer has a weight average molecular weight of 300,000 to 2.5 million. The pressure-sensitive adhesive composition for a flexible display according to any one of claims 1 to 5, wherein the first reactive group is a hydroxy group. The pressure-sensitive adhesive composition for a flexible display according to any one of claims 1 to 6, wherein the copolymer is obtained by living radical polymerization and has a molecular weight distribution (Mw / Mn) of less than 3.0. thing. An adhesive material for a flexible display for bonding one flexible member constituting a flexible display to another flexible member.
A pressure-sensitive adhesive material for a flexible display, wherein the pressure-sensitive adhesive material is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 7. An adhesive sheet for a flexible display having an adhesive layer used for adhering one flexible member constituting a flexible display and another flexible member, and a flexible sheet member attached to at least one surface of the adhesive layer. And,
A pressure-sensitive adhesive sheet for a flexible display, wherein the pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive material according to claim 8. The adhesive sheet has a first flexible sheet member attached to one surface of the adhesive layer and a second flexible sheet member attached to the other surface of the adhesive layer.
The first flexible sheet member is a first release sheet, and the second flexible sheet member is a second release sheet.
The adhesive sheet for a flexible display according to claim 9, wherein the first release sheet and the second release sheet are attached so that their respective release surfaces are in contact with the adhesive layer. A flexible laminated member including a first flexible member, a second flexible member, and an adhesive layer for bonding the first flexible member and the second flexible member to each other.
A flexible laminated member, wherein the adhesive layer is made of the adhesive material according to claim 8. The flexible laminated member according to claim 11, wherein at least one of the first flexible member and the second flexible member is a display element. A flexible display comprising the flexible laminated member according to claim 11 or 12.

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