JP2021134321A - Tacky material, tacky sheet and flexible laminate member - Google Patents

Abstract

To provide a tacky material capable of suppressing crack and deformation at a flexible position, even when the flexible laminate member is repeatedly bent, when used for adhesion of the flexible member constituting the flexible laminate member.SOLUTION: The tacky material is used to affix one flexible member and another flexural member, and the tacky material is a cured material of a tacky material containing the (meth)acrylic copolymer having a reactive functional group and a crosslinking gent, the (meth)acrylic copolymer is obtained from living radical polymerization, the molecular weight distribution is 3.0 or smaller, and the shear storage modulus of the tacky material at 23°C is 0.8×104 to 30×104 Pa, the Young's modulus of the tacky material is 10 to 1000 kPa, and after the tacky material is stretched until the tensile stress reaches 50 kPa, when the shrinkage test to release the tensile stress is repeated 10 times, the ratio of the modulus at the tenth shrinkage to the modulus at the first shrinkage is 60% or larger.SELECTED DRAWING: None

Description

The present invention relates to an adhesive material used for bonding one flexible member and another flexible member constituting a flexible laminated member that is repeatedly bent and used.

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, for example, in the form of a base material-attached pressure-sensitive adhesive sheet having a pressure-sensitive 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, a flexible display that is repeatedly bent and used in an image display device such as a liquid crystal display device or an organic electroluminescence (organic EL) display device has 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 1000% of the surfaces are displaced in opposite directions and the gel fraction are controlled within a predetermined range. The agent is disclosed (see Patent Document 1 (claim 1)).

Japanese Unexamined Patent Publication No. 2019-108498

In the conventional flexible member having an adhesive layer, when it is repeatedly bent, the recovery from the bent state to the original state is insufficient. Therefore, if the flexible laminated member is repeatedly bent, there is a risk 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. rice field.

The present invention has been made in view of the above circumstances, and when the flexible laminated member is used for bonding the flexible laminated member, even if the flexible laminated member is repeatedly bent, cracks are generated at the bent portion. It is an object of the present invention to provide an adhesive material capable of suppressing the occurrence of appearance defects such as waviness and waviness.

The pressure-sensitive adhesive material of the present invention that has been able to solve the above problems is a pressure-sensitive adhesive material used for bonding one flexible member and another flexible member, and the pressure-sensitive adhesive material has a reactive functional group. It is a cured product of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer and a cross-linking agent, and the (meth) acrylic copolymer is obtained by living radical polymerization, and the molecular weight distribution thereof. (Mw / Mn) of 3.0 or less, wherein a shear storage modulus of ^{0.8 × 10 4 Pa~30 × 10 4} Pa at 23 ° C. of the adhesive material, the Young's modulus of the adhesive material is 10kPa~ The pressure is 1000 kPa, and when the adhesive material is stretched until the tensile stress reaches 50 kPa and then the shrinkage test for releasing the tensile stress is repeated 10 times, the elastic modulus during contraction of the 10th time is higher than the elastic modulus during contraction of the first time. The ratio is 60% or more.

In the copolymer produced by free radical polymerization, the length of the obtained molecular chain is non-uniform, and the composition of each molecular chain is also non-uniform. Therefore, when such a copolymer is used as a pressure-sensitive adhesive, the distance between the cross-linking points cross-linked by the cross-linking agent becomes non-uniform, and it is considered that the obtained pressure-sensitive adhesive has a location where the elastic modulus is locally different. It is considered that the adhesive material having a non-uniform distance between the cross-linking points has a non-uniform elastic modulus when bent and stretched repeatedly, so that local fracture is likely to occur and plastic deformation is likely to occur.

The (meth) acrylic copolymer produced by living radical polymerization has a narrow molecular weight distribution and a uniform composition of each molecular chain. That is, the number of reactive functional groups contained in each molecular chain of the (meth) acrylic polymer becomes uniform. Therefore, when such a (meth) acrylic copolymer is used as the pressure-sensitive adhesive, the distances between the cross-linking points cross-linked by the cross-linking agent are uniform, and the obtained cured product (adhesive material) has almost the same elastic modulus as a whole. Come to have a rate. Since the entire adhesive material has almost the same elastic modulus, the occurrence of local breakage is suppressed even when bending and stretching are repeated, and the decrease in the force for returning to the original shape is suppressed even when bending and stretching are repeated. can.

Further, if the adhesive material has a predetermined shear storage elastic modulus and Young's modulus, and the maintenance rate of the elastic modulus at shrinkage in repeated shrinkage tests is high, the adhesive material follows the deformation of bending and stretching of the flexible member. be able to. Therefore, by using the adhesive material of the present invention, the occurrence of appearance defects such as cracks and waviness is suppressed without the occurrence of floating or peeling at the interface between the adhesive layer and the flexible member at the bent portion of the flexible laminated member. can.

When the adhesive material of the present invention is used for laminating the flexible members constituting the flexible laminated member, even if the flexible laminated member is repeatedly bent, the adhesive layer and the flexible member are at the interface at the bent portion. It is possible to suppress the occurrence of appearance defects such as cracks and waviness without the occurrence of floating or peeling.

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

Hereinafter, an example of a preferred embodiment in which the present invention has been carried out 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 methacryl". "(Meta) acrylate" refers to "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 capable of radical polymerization in the molecule. The "structural unit derived from a vinyl monomer" means a structural unit in which a radically polymerizable carbon-carbon double bond of a vinyl monomer is polymerized 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” refers to a structural unit in which a radically polymerizable carbon-carbon double bond of the (meth) acrylic monomer is polymerized into a carbon-carbon single bond.

[Adhesive]
The adhesive material of the present invention is an adhesive material used for bonding one flexible member and another flexible member constituting a flexible laminated member that is repeatedly bent and used. The pressure-sensitive adhesive is a cured product of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a reactive functional group and a cross-linking agent, and the (meth) acrylic copolymer is subjected to living radical polymerization. It is obtained, and its molecular weight distribution (Mw / Mn) is 3.0 or less. Also, the shear storage modulus at 23 ° C. of the adhesive material is ^{0.8 × 10 4 Pa~30 × 10 4} Pa, a Young's modulus of the adhesive material is 10KPa～1000kPa, the adhesive tensile stress When the shrinkage test for releasing the tensile stress is repeated 10 times after stretching to 50 kPa, the ratio of the elastic modulus at the 10th contraction to the elastic modulus at the first contraction is 60% or more. And.

The shear storage elastic modulus (G') of the pressure-sensitive adhesive at 23 ° C. is 0.8 × 10 ⁴ Pa or more, preferably 1.0 × 10 ⁴ Pa or more, and more preferably 2.0 × 10 ⁴ Pa or more. , 30 × 10 ⁴ Pa or less, more preferably 20 × 10 ⁴ Pa or less, further preferably 10 × 10 ⁴ Pa or less, and particularly preferably 8.0 × 10 ⁴ Pa or less. When the shear storage elastic modulus (G') is 0.8 × 10 ⁴ Pa or more, the adhesive material has appropriate flexibility and the shape followability is better, and when it is 30 × 10 ⁴ Pa or less, the adhesive material The cohesive force and adhesiveness of the material are improved. The method for measuring the shear storage elastic modulus (G') of the adhesive material will be described later.

The shear loss elastic modulus (G ″) of the pressure-sensitive adhesive at 23 ° C. ^{is preferably 0.40 × 10 4} Pa or more, more preferably 0.50 × 10 ⁴ Pa or more, and further preferably 1.0 × 10 ⁴ Pa or more. As described above, 27 × 10 ⁴ Pa or less is preferable, more preferably 18 × 10 ⁴ Pa or less, still more preferably 9.0 × 10 ⁴ Pa or less. Shear loss elastic modulus (G ″) is 0.40 ×. If it is 10 ⁴ Pa or more, the adhesive has appropriate flexibility and the shape followability to the adherend is good, and ^{if it is 27 × 10 4} Pa or less, the cohesive force and adhesiveness of the adhesive are better. Become. The method for measuring the shear loss elastic modulus (G ″) of the adhesive material will be described later.

The stress of the adhesive material immediately after applying the shear stress so as to have a shear strain of 200% ^{is preferably 5.0 × 10 4} Pa or more, more preferably 7.0 × 10 ⁴ Pa or more, and further preferably 7.0 × 10 4 Pa or more. It is 10 × 10 ⁴ Pa or more, ^{preferably 150 × 10 4} Pa or less, more preferably 100 × 10 ⁴ Pa or less, and further preferably 50 × 10 ⁴ Pa or less. When the stress is 5.0 × 10 ⁴ Pa or more, the cohesive force and adhesiveness of the adhesive material become better. When the stress is 150 × 10 ⁴ Pa or less, the adhesiveness is good.

The pressure of the adhesive material when a shear stress is applied so as to have a shear strain of 200% and the material is held for 10 minutes ^{is preferably 0.50 × 10 4} Pa or more, more preferably 0.70 × 10 ⁴ Pa. Above, more preferably 1.0 × 10 ⁴ Pa or more, preferably 8.0 × 10 ⁴ Pa or less, more preferably 5.0 × 10 ⁴ Pa or less, still more preferably 2.0 × 10 ⁴ Pa or less. Is. When the stress is 0.50 × 10 ⁴ Pa or more, the cohesive force and adhesiveness of the adhesive material become better. When the stress is 8.0 × 10 ⁴ Pa or less, when the adhesive material is used for the flexible laminate and bent, the stress applied to the bent portion can be satisfactorily relaxed to make it smaller. Therefore, it is possible to suppress the occurrence of cracks in the flexible member and the occurrence of floating or peeling at the interface between the adhesive layer and the flexible member.

The pressure-sensitive adhesive preferably has a recovery rate of 60% or more after applying shear stress so as to have a shear strain of 200%, holding the adhesive for 10 minutes, unloading the stress, and leaving the adhesive for 10 minutes. When the restoration rate is 60% or more, the deformation that occurs when the flexible laminated member is left in the bent state for a long time and then stretched is likely to be restored, so that the occurrence of appearance defects such as waviness at the bent portion is suppressed. can. The restoration rate is more preferably 65% or more, further preferably 75% or more, particularly preferably 85% or more, and the upper limit is 100%.

The Young's modulus of the pressure-sensitive adhesive is preferably 10 kPa or more, 25 kPa or more, more preferably 50 kPa or more, still more preferably 90 kPa or more, preferably 1000 kPa or less, 600 kPa or less, more preferably 500 kPa or less, still more preferably 400 kPa or less. be. If the Young's modulus is 10 kPa or more, appearance defects such as waviness can be suppressed even in a high temperature environment, and if it is 1000 kPa or less, floating and peeling at the time of bending can be suppressed even in a low temperature environment.

When the adhesive material was stretched to a tensile stress of 50 kPa and then the shrinkage test for releasing the tensile stress was repeated 10 times, the ratio of the elastic modulus at contraction of the 10th time to the elastic modulus at contraction of the first time was 60. % Or more. When the ratio is 60% or more, the amount of plastic deformation of the adhesive material becomes small even when the adhesive material is repeatedly bent and stretched. Therefore, when it is used for a flexible laminated member, it is possible to suppress the occurrence of appearance defects such as deformation marks at the bent portion. The ratio is preferably 70% or more, more preferably 80% or more, and the upper limit is 100%.

The elastic modulus at the time of the first shrinkage of the pressure-sensitive adhesive is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, further preferably 0.5 MPa or more, preferably 10 MPa or less, and more preferably 5.0 MPa or less. , More preferably 3.0 MPa or less.

In a shrinkage test in which the adhesive material is stretched until the tensile stress reaches 50 kPa and then the tensile stress is released, the elongation (first elongation) when the tensile stress is 50 kPa is preferably 10% or more, more preferably. It is 100% or more, more preferably 250% or more, and particularly preferably 500% or more. If the elongation is 10% or more, the aberration of the film at the time of bending can be absorbed. The upper limit of the elongation is not particularly limited, but is usually about 1000%.
The elongation is calculated by the following formula.
λ = (l _{1 −} l ₀ ) / l ₀ × 100
[Λ: Elongation (%), l ₀ : Length before extension (mm), l ₁ : Length after extension (mm)]

The gel fraction of the pressure-sensitive adhesive is preferably 20% to 100%, more preferably 50% to 100%, and particularly preferably 70% to 100% from the viewpoint of durability and adhesive strength. preferable. If the gel fraction is too low, lack of durability due to insufficient cohesive force is likely to occur. The gel fraction can be controlled by the blending amount of the cross-linking agent in the pressure-sensitive adhesive composition, the cross-linking treatment temperature, and the cross-linking treatment time.

(Adhesive composition)
The pressure-sensitive adhesive is a cured product of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a reactive functional group and a cross-linking agent. The pressure-sensitive adhesive composition contains (A) a (meth) acrylic copolymer having a reactive functional group and (B) a cross-linking agent.

((A) (meth) acrylic copolymer having a reactive functional group)
The (meth) acrylic copolymer having the (A) reactive functional group (hereinafter, may be simply referred to as “(A) copolymer”) is obtained by living radical polymerization. It is a (meth) acrylic copolymer having a molecular weight distribution (Mw / Mn) of less than 3.0 and having a reactive functional group.

The (meth) acrylic copolymer may be a copolymer containing 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 copolymer (A) is preferably 80% by mass or more, more preferably 90% by mass or more, based on 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, based on 100% by mass of the entire copolymer.

The copolymer (A) has a reactive functional group. The reactive functional group is a functional group that can react with the functional group of the (B) cross-linking agent described later. Examples of the reactive functional group include one or more selected from the group consisting of a hydroxy group, a carboxy group and an epoxy group, and a hydroxy group and / or a carboxy group are preferable.

The amount of the reactive functional group per 100 g of the (A) copolymer is preferably 0.5 mmol / 100 g or more, more preferably 5 mmol / 100 g or more, still more preferably 10 mmol / 100 g or more, and particularly preferably 15 mmol / 100 g or more. It is preferably 150 mmol / 100 g or less, more preferably 100 mmol / 100 g or less, still more preferably 70 mmol / 100 g or less, and particularly preferably 50 mmol / 100 g or less. When the amount of the reactive functional group is 0.5 mmol / 100 g or more, the durability of the pressure-sensitive adhesive is excellent, and when it is 150 mmol / 100 g or less, the adhesion of the pressure-sensitive adhesive to the adherend is excellent.

When the (A) copolymer has a carboxy group, the amount of the carboxy group per 100 g of the (A) copolymer is preferably 0.5 mmol / 100 g or more, more preferably 5 mmol / 100 g or more, still more preferably. It is 10 mmol / 100 g or more, particularly preferably 15 mmol / 100 g or more, preferably 150 mmol / 100 g or less, more preferably 100 mmol / 100 g or less, still more preferably 70 mmol / 100 g or less, and particularly preferably 50 mmol / 100 g or less.

When the (A) copolymer has a hydroxy group, the amount of carboxy group per 100 g of the (A) copolymer is preferably 0.5 mmol / 100 g or more, more preferably 5 mmol / 100 g or more, still more preferably. It is 10 mmol / 100 g or more, particularly preferably 15 mmol / 100 g or more, preferably 150 mmol / 100 g or less, more preferably 100 mmol / 100 g or less, still more preferably 70 mmol / 100 g or less, and particularly preferably 50 mmol / 100 g or less.

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

The content of the structural unit (structural unit (a-1) having a reactive functional group) derived from the vinyl monomer having a reactive functional group in the (A) copolymer is 100% by mass of the whole copolymer. In, 0.1% by mass or more is preferable, more preferably 0.5% by mass or more, further preferably 1% by mass or more, particularly preferably 3% by mass or more, preferably 20% by mass or less, and more preferably. Is 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 8% by mass or less. When the content of the structural unit (a-1) is within the above range, an adhesive material having an excellent balance between adhesion to an adherend and durability can be obtained. The vinyl monomer having a reactive functional group includes a (meth) acrylic monomer having a reactive functional group and a vinyl monomer other than the (meth) acrylic monomer having a reactive functional group.

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

The (meth) acrylic monomer having no reactive functional group (b1) includes a (meth) acrylate having a linear alkyl group, a (meth) acrylate having a branched alkyl group, and an alkoxy group (meth). ) Acrylate, (meth) acrylate having a polyalkylene glycol structural unit, (meth) acrylate having an alicyclic hydrocarbon group, (meth) acrylate having an aromatic group, (meth) acrylate having a tertiary amino group, ( Meta) acrylamides and the like can be mentioned. 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 the 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) acrylate linear alkyl Acrylate 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 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 the 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. Polypropylene glycol (meth) acrylate having polyethylene glycol structural units 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 (degree of polymerization = 2-10) ethyl ether (meth) acrylate, polypropylene glycol (degree of polymerization = 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 a (meth) acrylate having a cyclic alkyl group and a (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 in the cyclic alkyl group. Examples of the cyclic alkyl group include a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group), and may also 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 also 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 in the aromatic group. Examples of the aromatic group include an aryl group and the like, and may have a chain portion such as an alkylaryl group, an aralkyl 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 aralkyl group preferably has 6 to 12 carbon atoms. 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 meta) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, and N- (meth) acrylmorpholin. The (meth) acrylamides are (meth) acrylic monomers, but are not included in the (meth) acrylate monomers.

Examples of the (meth) acrylic monomer having the (b2) reactive functional group include a (meth) acrylic monomer having a hydroxy group (preferably a (meth) acrylate monomer) and a (meth) acrylic monomer having a carboxy group (preferably (meth) acrylic monomer. Examples thereof include (meth) acrylic acid) and (meth) acrylic monomers having an epoxy group (preferably (meth) acrylate monomers). 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) acrylate is preferable, and (meth) acrylate having a hydroxyalkyl group having 1 to 5 carbon atoms is 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 reactive functional group and (b4) a vinyl monomer other than the (meth) acrylic monomer having a reactive functional group. Vinyl monomers can be mentioned. 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 reactive functional group (b3) include an aromatic vinyl monomer, a vinyl monomer containing a heterocycle, vinyl carboxylate, and a vinyl monomer containing a tertiary amino group. , Vinyl monomers containing a quaternary ammonium base, vinylamides, 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 vinylamides 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 and 1,2-dichloro-1,2-difluoroethylene.

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

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, cinnamic acid and the like.
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 200,000 or more, more preferably 300,000 or more, further preferably 400,000 or more, 2 million or less, and more preferably 1.8 million or less. , More preferably 1.5 million or less, and particularly preferably 1 million or less. When the Mw of the copolymer (A) is 200,000 or more, the cohesive force is increased and the heat resistance of the pressure-sensitive adhesive is improved, and when it is 2 million or less, the coating workability of the pressure-sensitive adhesive composition is further improved. The method for measuring the weight average molecular weight (Mw) will be described later.

The molecular weight distribution (PDI) of the copolymer (A) is 3.0 or less, preferably less than 3.0, more preferably less than 2.5, and even more preferably less than 2.2. Particularly preferably, it is less than 1.8. The smaller the PDI, the narrower the width of the molecular weight distribution, and the copolymer has a uniform molecular weight. When the value is 1.0, the width of the molecular weight distribution is the narrowest. When the PDI is 3.0 or less, the content of the one having a small molecular weight or the one having a large molecular weight is low as compared with the molecular weight of the designed copolymer, and an adhesive material 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 copolymer (A) 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. If the glass transition temperature is −70 ° C. or higher, sufficient cohesive force is given to the adhesive material and the durability of the adhesive material is improved. Etc. are suppressed and durability is improved.

The glass transition temperature (Tg) of the copolymer (A) is a value calculated by the following FOX formula (mathematical 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 to 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. It is easy to produce a polymer with a uniform composition and precise control. 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 copolymer (A). Further, a block copolymer can be obtained 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 organotellurium 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. It is 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 of polymerizing a vinyl monomer using an organic tellurium compound represented by the formula (1).
(B) A method of 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 of 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 of 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 the formula (2), R ¹ is an alkyl group having 1 to 8 carbon atoms, an aryl group or an aromatic heterocyclic group. ]

Specifically, the organic tellurium compound represented by the formula (1) is 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, dibutyl diterlide and the like. 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 the reaction according to 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 aprotic solvents 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 according to 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 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 derived from the tellurium compound (R ¹ is the same as above in the formula), and is inactivated by an operation in air after the completion of the polymerization reaction. However, tellurium atoms may remain. It is preferable to remove the tellurium atom because the copolymer in which the tellurium atom remains at the terminal is colored or has poor thermal stability. 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. It is the same ^{as R 2} , R ³ and R ^{4 in} (1)).

((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 reactive groups in one molecule capable of reacting with the reactive functional groups 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, epoxy-based cross-linking agents, and aziridine-based cross-linking agents are preferable, and from the viewpoint of easy control of the degree of progress of the cross-linking reaction and bending resistance, isocyanate-based cross-linking agents or epoxy-based cross-linking agents are used. The agent is more preferred.

(Isocyanate 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 reactive group in one molecule. 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 aromatic polyisocyanates, alicyclic polyisocyanates, aliphatic polyisocyanates, adducts of these and various polyols, isocyanurate bonds, burette bonds, allophanate bonds, and the like. Examples thereof include polyisocyanates. More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, 1,3-bis (isocyanatomethyl). ) Alicyclic polyisocyanates such as cyclohexane; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate Aromatic polyisocyanates such as isocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalenediocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate; trimethylol propane / tolylene diisocyanate trimer adduct, trimethylol propane / Hexamethylene diisocyanate trimeric adduct, isocyanate adduct such as isocyanurate of hexamethylene diisocyanate; trimethylol propane adduct of xylylene diisocyanate; trimethylol propane adduct of hexamethylene diisocyanate; polyether polyisocyanate, polyester poly One or more selected from isocyanates and adducts of these with various polyols, polyisocyanates polyfunctionalized by isocyanurate bond, burette bond, allophanate bond and the like can be used. Of these, it is preferable to use an aliphatic polyisocyanate, and an isocyanurate form of an aliphatic diisocyanate (for example, an isocyanurate form of hexamethylene diisocyanate) is more 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 reactive group. The epoxy-based cross-linking agent may be used alone or in combination of two or more.

Examples of the epoxy cross-linking agent include bisphenol A, epichlorohydrin type epoxy 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 , Adipate diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether and the like.

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

Examples of the aziridine-based cross-linking agent include tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, and hexa [1- (2). -Methyl) -aziridinyl] Triphosphatriazine and the like can be mentioned.

The content of the reactive group of the cross-linking agent (B) is preferably 0.5 mmol / g or more, more preferably 1.0 mmol / g or more, still more preferably 3.0 mmol / g or more, and particularly preferably 6. It is 0 mmol / g or more, preferably 20 mmol / g or less, more preferably 15.0 mmol / g or less, still more preferably 12.0 mmol / g or less. When the content of the reactive group of the cross-linking agent (B) is within this range, the cohesive force of the pressure-sensitive adhesive becomes preferable, and even if it is bent, the occurrence of deformation at the bent portion can be further suppressed.

The content of the cross-linking agent (B) in the pressure-sensitive adhesive composition is preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, and 1 part by mass with respect to 100 parts by mass of the copolymer (A). The following is preferable, and more preferably 0.5 parts by mass or less. When the content of the cross-linking agent (B) is 0.01 parts by mass or more, sufficient cohesive force is exhibited and excellent flexibility is exhibited. If it is 1 part by mass or less, sufficient adhesion to the base material can be exhibited and the occurrence of floating and peeling at the time of bending can be suppressed.

The pressure-sensitive adhesive composition has a molar ratio of reactive functional groups (molar amount of reactive functional groups / molar amount of reactive groups) of the copolymer (A) to the reactive groups of the cross-linking agent (B). It is preferably 1 or more, more preferably 2 or more, still more preferably 10 or more, preferably 1000 or less, more preferably 200 or less, still more preferably 100 or less.

(Other additives)
In addition to the (A) copolymer and (B) cross-linking agent, other additives may 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, etc. Antistatics, wetting agents, surfactants, thickeners, fungicides, preservatives, oxygen absorbers, UV absorbers, antioxidants, near-infrared absorbers, water-soluble quenchers, fragrances, metal deactivators , 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 blended and used in the pressure-sensitive adhesive composition. Examples of the cross-linking accelerator include an organotin compound and a metal chelate compound. The cross-linking accelerator may be used alone or in combination of two or more.

Examples of the organotin compound include dibutyltin dilaurate, dioctiolstin dilaurylate, and dibutyltin dioctylate. The metal chelate compound is a complex in which ligands having two or more coordination atoms form a ring and are 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 within the above range, it is possible to obtain an excellent cross-linking promoting effect.

(Crosslink retarder)
If necessary, a cross-linking retarder can be blended and used in the pressure-sensitive adhesive composition. The cross-linking retarder is a compound in a pressure-sensitive adhesive composition containing a cross-linking agent, which can suppress an excessive increase in viscosity of the pressure-sensitive adhesive composition by blocking the functional groups of the cross-linking agent. The type of the cross-linking retarder is not particularly limited, but β-diketones such as acetylacetone, hexane-2,4-dione, heptane-2,4-dione, octane-2,4-dione; Β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetic acid, octyl acetoacetic acid, oleyl acetoacetic acid, lauryl acetoacetic acid and stearyl acetoacetic acid; 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 within the above range, after the (B) cross-linking agent is blended into 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 Storage stability (pot life) can be extended.

(Silane coupling agent)
A silane coupling agent can be blended and used in the pressure-sensitive adhesive composition, if necessary. 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 thereof include (meth) acrylic group-containing silane coupling agents such as methacryloxypropyltriethoxysilane; and 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 parts by mass to 0.6 parts by mass. By adjusting the content of the silane coupling agent within 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.

(Adhesive imparting agent)
If necessary, the pressure-sensitive adhesive composition can be used by blending a pressure-sensitive adhesive other than the (A) copolymer. The tackifier 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 ester-based resins obtained by modifying rosin ester-based resins with unsaturated fatty acids. A rosin alcohol-based resin obtained by reducing the 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.

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), resol obtained by addition-reacting the phenols and formaldehyde with an alkali catalyst, novolac obtained by condensing the phenols and formaldehyde 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 penten-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 dimeric. Alicyclic hydrocarbon-based resins that have been embodied and then polymerized, polymers of cyclic diene compounds (cyclopentadiene, dicyclopentadiene, etilidennorbornene, dipentene, etc.) or their hydrogen additions, the following aromatic hydrocarbon resins, and Alicyclic hydrocarbon-based resins with hydrogenated aromatic rings of aliphatic / aromatic petroleum resins], aromatic hydrocarbon resins [vinyl group-containing aromatic hydrocarbons with 8 to 10 carbon atoms (styrene) , Vinyl toluene, α-methylstyrene, inden, methylindene, 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 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, still more preferably 10 parts by mass or more, based on 100 parts by mass of the (A) copolymer. It is 20 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 to the above range, sufficient adhesion to the adherend can be ensured, and floating and peeling at the time of bending can be suppressed.

(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 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. Such as ketones; 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 these solvents 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 material)
The use of the adhesive material is not particularly limited and can be used for a wide range of applications, but is particularly preferably used for a flexible display that can be repeatedly bent and used, and a member 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 tubular shape. Flexible displays are expected to be used in mobile terminals such as smartphones and tablet terminals, and stationary displays that can be stored.

[Adhesive sheet]
The adhesive sheet of the present invention has an adhesive layer used for adhering one flexible member and another flexible member, and a flexible sheet member attached to at least one surface of the adhesive layer. However, the pressure-sensitive adhesive layer is characterized in that it 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 adhesive sheet 10 of FIG. 1 is composed of an adhesive layer 12, a first flexible sheet member 14 that sandwiches the 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 thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and particularly preferably 20 μm or more. When the thickness of the adhesive layer is 5 μm or more, sufficient adhesion to the flexible sheet member can be obtained. The thickness of the adhesive layer is preferably 100 μm or less, more preferably 75 μm or less, and further preferably 50 μm or less. When the thickness of the adhesive layer is 100 μm or less, the adhesive layer can be suppressed from protruding.

The adhesive force of the adhesive layer on the flexible sheet member (excluding the release sheet) at 23 ° C. is preferably 10 N / 25 mm or more, more preferably 15 N / 25 mm or more, still more preferably 20 N / 25 mm or more. If it is 10 N / 25 mm or more, it is possible to suppress the floating and peeling of the adhesive material. The upper limit of the adhesive strength is not particularly limited, but is usually 50 N / 25 mm or less, preferably 40 N / 25 mm or less.

(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 this 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, a "sheet" is a flat product that is thin by definition in JIS and whose thickness is generally small for its length and width, and a "film" is generally referred to as a "film" in comparison with its 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 polymer material sheet and a glass sheet. 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 polyester resins such as polyethylene terephthalate resin and polyethylene naphthalate resin; polycarbonate resin; poly (meth) acrylate resin; polystyrene resin; polyamide resin; polyimide resin; polyacrylonitrile resin; polypropylene resin, polyethylene resin, and poly. Polyolefin resins such as cycloolefin resins and cycloolefin copolymer resins; cellulose resins such as triacetyl cellulose resins and diacetyl cellulose resins; polyphenylene sulfide resins; polyvinyl chloride resins; polyvinylidene chloride resins; polyvinyl alcohol resins and the like can be mentioned.

The flexible sheet member may be composed of a single layer composed of a layer containing one or more of the polymer materials, or may be composed of a layer containing one or more of the polymer materials and a 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 this 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 in 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. 1 The flexible sheet member is the first release sheet, the second flexible sheet member is the 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. It is preferable that it is worn. 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 first flexible sheet member is applied. After forming the adhesive layer on the adhesive layer, the second flexible sheet member may be attached to the 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 40 ° C.

[Flexible laminated member]
The flexible laminated member of the present invention includes 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. It is a laminated member, and the adhesive layer is 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, the interface between the adhesive layer and the flexible member at the bent portion does not float or peel off. , Appearance defects such as cracks and waviness 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 located between the first flexible member 22, the second flexible member 24, and the first flexible member 22 and the second flexible member 24, and these bending members are connected to each other. It is provided with an adhesive layer 12 to be bonded.

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 Examples thereof include a configuration in which the flexible member is a functional sheet member bonded to the flexible device. Examples of the flexible device include a foldable foldable display and a rollable display that can be rolled into a tubular shape. 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 and used. 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.

(Manufacturing method of flexible laminated member)
The method for producing 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. A method in which a sheet is peeled off and an exposed adhesive layer and a second flexible member are attached to obtain a flexible laminated member.
(2) An adhesive composition is applied to one surface of the first flexible member, and if necessary, it is cured by a dry heat treatment to form an adhesive layer, and then the adhesive layer is provided with the releasability of a release sheet. Attach the surface to be held. 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, it is 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 wearing and obtaining a flexible laminated member.
(4) An adhesive composition is applied onto the releasable surface of the release sheet, and if necessary, it is cured by dry heat treatment to form an adhesive layer, and then a first flexible member is attached to the adhesive layer. To wear. 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 changed.
For the formation of the pressure-sensitive adhesive layer, various coating methods and various printing methods similar to those for producing the pressure-sensitive 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 in the manufacture of the flexible laminated member may be the same as the release sheet used for the adhesive sheet.

(Specific example of flexible laminated member)
Hereinafter, a preferred embodiment of the flexible laminated member of the present invention will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view of a specific example of the flexible laminated member of the present invention. The flexible laminated member 30 shown in FIG. 3 is located between the first flexible member 32, the second flexible member 34, and the first flexible member 32 and the second flexible member 34. It is provided with an adhesive layer 12 for adhering each other. The first flexible member 32 is a cover film, which has a cover film base material 32a and a hard coat layer 32b, and the cover film base material 32a is attached to the adhesive layer 12. ing. Further, the second flexible member 34 is a polarizing film.

The adhesive layer 12 suppresses floating and peeling of the interface with the first flexible member 32 and the second flexible member 34 at the bent portion. Therefore, it is possible to suppress the occurrence of cracks in the hard coat layer 32b provided on the cover film (first flexible member) 32 when the flexible laminated member 30 is repeatedly bent.

(Cover film base material)
The cover film base material 32a is not particularly limited as long as it has flexibility and transparency. Examples of the cover film base material 32a include a transparent polymer film and a transparent glass film. Transparency means that the total light transmittance in the visible light wavelength region is 50% or more. The total light transmittance is more preferably 85% or more. The total light transmittance is measured according to JIS K7361-1 (1997).

The yellowness (YI value) of the cover film base material 32a is preferably 20 or less, more preferably 10 or less, and further preferably 5 or less. As a result, it is possible to obtain a display that displays an image having high transparency and high color reproducibility. The yellowness (YI value) is measured according to JIS K 7373 (2006).

The thickness of the cover film base material 32a is not particularly limited, but is preferably 2 μm to 500 μm, and more preferably 2 μm to 200 μm from the viewpoint of handleability.

Examples of the polymer material of the polymer film used as the cover film base material 32a include polyester resin (polyethylene terephthalate resin, polyethylene naphthalate resin, etc.), polycarbonate resin, poly (meth) acrylate resin, polystyrene resin, polyamide resin, and polyimide. Resin, polyacrylonitrile resin, polyolefin resin (polypropylene resin, polyethylene resin, polycycloolefin resin, cycloolefin copolymer resin, etc.), cellulose-based resin (triacetylcellulose resin, diacetylcellulose resin, etc.), polyphenylene sulfide resin, polyvinyl chloride resin , Polyvinylidene chloride resin, polyvinyl alcohol resin and the like.

The polymer material may be composed of only one type, or may be composed of a combination of two or more types. From the viewpoint of optical properties, durability, etc., the polymer material consists of a group consisting of polyethylene terephthalate resin, polyimide resin, polycarbonate resin, poly (meth) acrylate resin, polycycloolefin resin, cycloolefin copolymer resin and triacetylcellulose resin. It is preferable to contain at least one selected, and it is particularly preferable to contain a polyimide resin. The film containing the polyimide resin has flexibility to withstand repeated bending, and is excellent in surface hardness and heat resistance. The content of the polyimide resin in the polymer material is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. The polymer material may be composed only of the polyimide resin.

The cover film base material 32a may have a single-layer structure or a multi-layer structure having two or more layers. Further, each layer of the cover film base material 32a may be composed of only one kind of the polymer material, or may be composed of two or more kinds of the polymer material.

(Hard coat layer)
The pencil hardness of the hard coat layer 32b is preferably 3H or more, more preferably 4H or more. The pencil hardness of the hard coat layer 32b is the pencil hardness of the surface of the hard coat layer 32b formed on one surface of the cover film base material 32a, and the adhesive layer 12 is formed on the other surface of the cover film base material 32a. It is measured in the unfinished state. The pencil hardness of the hard coat layer 32b is measured according to JIS K 5600-5-4.

The thickness of the hard coat layer 32b is preferably 0.5 μm or more, more preferably 1.0 μm or more, further preferably 3.0 μm or more, preferably 10.0 μm or less, more preferably 8.0 μm or less, and further. It is preferably 6.0 μm or less. When the thickness is 0.5 μm or more, the pencil hardness of the cover film 32 is sufficiently secured. When the thickness is 10.0 μm or less, the cover film has sufficient flexibility to withstand repeated bending, and the cover film 32 due to the difference in heat shrinkage between the hard coat layer 32b and the cover film base material 32a. Curl is suppressed. The thickness of the hard coat layer 32b is the thickness of the smooth portion, and when the hard coat layer contains particles, it is the thickness of the smooth portion in the portion without unevenness caused by the particles in the thickness direction. be.

The hard coat layer 32b is preferably composed of a cured product of a curable composition containing an ultraviolet curable compound from the viewpoints of high hardness, high flexibility, productivity and the like.

Examples of the ultraviolet curable compound include monomers, oligomers, prepolymers and the like having an ultraviolet reactive reactive group. Examples of the ultraviolet-reactive reactive group include a radical polymerization type reactive group having an ethylenically unsaturated bond such as a (meth) acryloyl group, an allyl group and a vinyl group; and a cationic polymerization type reactive group such as an oxetanyl group. Can be mentioned. Among these, as the UV-reactive reactive group, a (meth) acryloyl group and an oxetanyl group are more preferable, and a (meth) acryloyl group is particularly preferable.

Examples of the compound having a (meth) acryloyl group include urethane (meth) acrylate, silicone (meth) acrylate, alkyl (meth) acrylate, and aryl (meth) acrylate. In particular, urethane (meth) acrylate is preferable from the viewpoint of being relatively flexible and improving the flexibility of the hard coat film.

The urethane (meth) acrylate is obtained by an addition reaction with a polyol, an isocyanate compound, and a (meth) acrylate having a hydroxy group. Examples of the polyol include polyether polyols, polyester polyols, polycarbonate polyols and the like, which can be appropriately selected from the viewpoints of flexibility, heat resistance, chemical resistance and the like.

Examples of the isocyanate compound include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; 1,4-cyclohexanediisocyanate, isophorone diisocyanate, and 4,4'-dicyclohexylmethane. Examples thereof include alicyclic diisocyanates such as diisocyanate, methylcyclohexanediisocyanate, isopropyridene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, and 4-methyl-1,3-cyclohexylene diisocyanate. ..

The compound having a (meth) acryloyl group may be a monofunctional (meth) acrylate having one (meth) acryloyl group in the molecule, or a polyfunctional (meth) acryloyl group having two or more (meth) acryloyl groups in the molecule. It may be (meth) acrylate. The compound having a (meth) acryloyl group preferably contains a polyfunctional (meth) acrylate.

Examples of the monofunctional (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, and isobutyl (meth) acrylate. , T-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl ( Meta) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) ) Acrylate, Isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, Bornyl (meth) acrylate, tricyclodeca Nyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate, 2-naphthylmethyl (meth) ) Acrylate, phenoxyethyl (meth) acrylate, phenoxy-2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, 2-phenylphenoxyethyl (meth) Acrylate, 4-phenylphenoxyethyl (meth) acrylate, 3- (2-phenylphenyl) -2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) ) Acrylate, ethoxye Examples thereof include chill (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate.

Examples of the polyfunctional (meth) acrylate include bifunctional (meth) acrylate, trifunctional (meth) acrylate, and tetrafunctional (meth) acrylate. Specifically, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol. Di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylpropantri (meth) acrylate, Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra (meth) acrylate, tripentaerythritol penta (meth) Examples thereof include acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, and tripentaerythritol octa (meth) acrylate.

The curable composition may or may not contain a non-UV curable resin in addition to the UV curable compound. In addition, the curable composition may contain a photopolymerization initiator. In addition, the curable composition may contain an additive and a solvent, if necessary. Examples of the additive include inorganic particles, resin particles, antifouling agent, dispersant, leveling agent, defoaming agent, stiffener, antifouling agent, antibacterial agent, flame retardant, slip agent and the like.

Examples of the non-ultraviolet curable resin include thermoplastic resins and thermosetting resins. Examples of the thermoplastic resin include polyester resin, polyether resin, polyolefin resin, and polyamide resin. Examples of the thermosetting resin include unsaturated polyester resin, epoxy resin, alkyd resin, and phenol resin.

Examples of the photopolymerization initiator include alkylphenone-based, acylphosphine oxide-based, and oxime ester-based photopolymerization initiators. Examples of the alkylphenone-based photopolymerization initiator include 2,2'-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-hydroxy-2-methyl-1-phenyl-. Propane-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-1- {4- [4-( 2-Hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 2-benzylmethyl-2- (dimethylamino) -1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- (4-morpholino) Examples thereof include phenyl) -1-butanone, 2- (4-methylbenzyl) -2- (dimethylamino) -1- (4-morpholinophenyl) -1-butanone, and N, N-dimethylaminoacetophenone. Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and bis (2,6-dimethoxybenzoyl) -2. , 4,4-trimethyl-Pentylphosphine oxide and the like. Examples of the oxime ester-based photopolymerization initiator include 1,2-octanedione, 1- [4- (phenylthio) phenyl] -2- (O-benzoyloxime), and ethanone-1- [9-ethyl-6- (2-). Methylbenzoyl) -9H-carbazole-3-yl] -1- (O-acetyloxime) and the like can be mentioned. The photopolymerization initiator may be used alone or in combination of two or more.

The content of the photopolymerization initiator is preferably 0.1% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, based on the total solid content of the curable composition.

Inorganic particles and resin particles are added to the hard coat layer for the purpose of preventing blocking, improving the hardness of the hard coat layer, imparting antiglare property, and the like. Examples of the inorganic particles include metal oxide particles made of metal oxides such as silica, titanium, zirconium, tin, zinc, silicon, niobium, aluminum, chromium, magnesium, germanium, gallium, antimony, and platinum. These inorganic particles may be used alone or in combination of two or more. Among these, titanium oxide particles, zirconium oxide particles, and tin oxide particles are preferable from the viewpoint of excellent compatibility between high hardness and transparency.

The resin particles include, for example, resin particles made of a resin such as (meth) acrylic resin, styrene resin, styrene- (meth) acrylic resin, urethane resin, polyamide resin, silicone resin, epoxy resin, phenol resin, polyethylene resin, and cellulose. Can be mentioned. These resin particles may be used alone or in combination of two or more.

Examples of the antifouling agent include fluorine-containing compounds. Examples of the fluorine-containing compound include (meth) acrylates containing a perfluoroalkyl group. Examples of such compounds include "X-71-1203M" manufactured by Shin-Etsu Chemical, "Megafuck (registered trademark) RS-75" manufactured by DIC, "Optur (registered trademark) DAC-HP" manufactured by Daikin Industries, and "Neos". "Futagent (registered trademark) 601AD" and the like can be mentioned. The fluorine-containing compound can suppress the adhesion of stains and fingerprints and facilitate the removal of stains and fingerprints. The content of the fluorine-containing compound is preferably 0.01% by mass to 15% by mass, more preferably 0.05% by mass to 10% by mass, still more preferably 0.2% by mass, based on the total amount of the hard coat layer 32b. ~ 5% by mass. When the content of the fluorine-containing compound is within the above range, excellent antifouling property and anti-fingerprint property can be obtained.

Examples of the solvent used in the curable composition forming the hard coat layer 32b include alcohol solvents (ethanol, isopropyl alcohol, n-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, and diethylene glycol mono). Butyl ether, etc.), Ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, etc.), aromatic solvents (toluene, xylene, etc.), ester solvents (ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, etc.), amides Examples include system solvents (N-methylpyrrolidone, acetamide, dimethylformamide, etc.) and the like. These solvents may be used alone or in combination of two or more.

The solid content concentration (concentration of components other than the solvent) of the curable composition may be appropriately determined in consideration of coatability, film thickness, etc., and is, for example, 1% by mass to 90% by mass, preferably 1. It is 5% by mass to 80% by mass, more preferably 2% by mass to 70% by mass.

(Manufacturing of cover film)
The cover film can be manufactured by forming the hard coat layer 32b on one surface of the cover film base material 32a. The hard coat layer 32b can be formed by applying a composition for forming the hard coat layer on one surface of the cover film base material 32a, and if necessary, drying, irradiating with ultraviolet rays, or the like.

In order to improve the adhesion between the cover film base material 32a and the hard coat layer 32b, the surface of the cover film base material 32a is subjected to surface treatment such as corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment. You may. Further, an easy-adhesion layer may be provided on the surface of the cover film base material 32a. Further, various functional layers such as a gas barrier property improving layer, an antistatic layer, and an oligomer block layer may be provided on the surface of the cover film base material 32a. Further, another hard coat layer may be provided between the cover film base material 32a and the adhesive layer 12.

For coating the composition forming the hard coat layer 32b, coating methods (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) are performed. The method, spray coating method, knife coating method, kiss coating method, etc.), inkjet method, printing method (offset printing, screen printing, flexo printing, etc.) can be adopted.

The drying is not particularly limited as long as the solvent used in the coating liquid can be removed, but the drying is preferably performed at 50 ° C. to 150 ° C. for about 10 seconds to 180 seconds, and particularly preferably 50 ° C. to 120 ° C.

For ultraviolet irradiation, a high-pressure mercury lamp, an electrodeless (microwave method) lamp, a xenon lamp, a metal halide lamp, or any other ultraviolet irradiation device can be used. The ultraviolet irradiation may be carried out in an atmosphere of an inert gas such as nitrogen, if necessary. UV irradiation dose, but are not limited to, preferably ^{50mJ / cm 2 ~800mJ / cm 2} , 100mJ / cm 2 ~300mJ / cm 2 is more preferable.

(Polarizing film)
The polarizing film can be, for example, one in which a protective film is attached to at least one surface of the polarizer via an adhesive layer. Further, another optical functional film such as a retardation film or a barrier film may be laminated on the polarizer or the protective film via an adhesive layer or an adhesive material.

The polarizer is a film having a function of passing only light polarized in a specific direction, and for example, a polyvinyl alcohol-based resin film that is uniaxially stretched and iodine is oriented can be used. The thickness of the polarizer is, for example, 1 μm to 12 μm, preferably 1 μm to 9 μm, and more preferably 3 μm to 6 μm.

The protective film may be the same as the base material used for the cover film. The thickness of the protective film is not particularly limited, but is preferably 2 μm to 500 μm, and more preferably 2 μm to 200 μm from the viewpoint of handleability.

Further, this protective film may also function as a retardation film. The retardation film is an optical film that exhibits optical anisotropy, and can be formed by stretching a film made of a resin or the like that can be used as a protective film, or by applying a liquid crystal compound to a base film. It can be formed by a method of orientation and hardening. When the polarizing film is used as an antireflection circular polarizing plate of an organic EL display device, the retardation film gives a retardation of λ / 4 (90 °) and changes linearly polarized light into circularly polarized light, λ / 4 It is preferably a plate.

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. The polymerization modulus of block copolymer, weight average molecular weight (Mw), molecular weight distribution (PDI), gel fraction of adhesive material, adhesive layer thickness, Young's modulus, elastic modulus at shrinkage, shear storage elastic modulus, shear stress , Restoration rate, etc. were evaluated according to the following method.

The meanings of the abbreviations are as follows.
BA: n-butyl acrylate LA: lauryl acrylate EHA: 2-ethylhexyl acrylate IBXA: isobornyl acrylate ACMO: acryloylmorpholin AA: acrylic acid HBA: 4-hydroxybutyl acrylate DMAAm: dimethylacrylamide 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 peaks of the vinyl group derived from the monomer and the ester side chain 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 as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were a column temperature of 40 ° C., a sample concentration of 10 mg / mL, a sample injection amount of 10 μm, and a flow velocity of 0.2 mL / min. Polystyrene (molecular weight 2,890,000, 1,090,000, 775,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630,440) is used as a standard substance. Then, a calibration curve (calibration curve) was prepared, 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.

(Gel fraction)
The mass W1 of a wire mesh (400 mesh) cut out having a width of 50 mm and a length of 120 mm was measured. 0.1 g of a sheet-shaped adhesive was collected and wrapped with a wire mesh so that the adhesive did not fall off to prepare a test piece, and the mass W2 of this test piece was measured. 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 76 hours. After allowing to stand, the test piece was taken out from the glass bottle, left at room temperature for 12 hours, 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 (mass%) = ((W3-W1) / (W2-W1)) x 100

(Young's modulus)
A sheet-shaped adhesive (thickness 1 mm) was cut into a size of 5 mm in width and 70 mm in length to prepare a test piece. The tensile test was performed using a precision universal testing machine (AUTOGRAPH® AGX manufactured by Shimadzu Corporation). In the test, the distance between the gripping tools was 30 mm, the tensile speed was 30 mm / min, and the tensile stress was extended from 0 kPa to 50 kPa in an environment of 23 ° C. and 50%. For the obtained stress-strain curve, the average value of the slopes of the tangents at the distance between the grips of 30.9 to 31.8 mm (displacement from the initial distance between the grips of 3 to 6%) was defined as Young's modulus.

(Elastic modulus during contraction)
A sheet-shaped adhesive (thickness 1 mm) was cut into a size of 5 mm in width and 70 mm in length to prepare a test piece. The test was carried out using a precision universal testing machine (AUTOGRAPH® AGX manufactured by Shimadzu Corporation). In the test, the distance between the gripping tools was 30 mm and the tensile speed was 30 mm / min in an environment of 23 ° C. and 50%. In the test, the tensile stress was extended from 0 kPa until the tensile stress became 50 kPa, then contracted until the tensile stress became 0 kPa, and the tensile stress at each elongation at the time of contraction was recorded. This stretching and contraction was repeated 10 times, and the elastic modulus at the time of contraction at the time of the first contraction and the tenth contraction was calculated.
The contractile elastic modulus is the tensile stress and displacement at a displacement of 0.97, where 1 is the displacement from the test piece length at the tensile stress of 50 kPa at the nth contraction to the test piece length at the tensile stress of 0 kPa at the nth contraction. It was obtained from the tensile stress at 0.94.

(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.

(Shear storage elastic modulus, shear loss elastic modulus)
Adhesive layers (sheet-like adhesives) constituting the adhesive sheet were bonded and laminated using a hand roller to prepare a laminated body having a thickness of 0.5 mm. Using this laminate as a sample, using a viscoelasticity measuring device (Discovery HR-2, manufactured by TA instrument), in an environment of 23 ° C. and 50%, shear mode, geometry: 8 mm diameter parallel plate, frequency: 1 Hz, strain: The shear storage elastic modulus and the shear loss elastic modulus were measured at 1%.

(Stress when shear stress is applied and held for 10 minutes, and restoration rate)
Adhesive layers (sheet-like adhesives) constituting the adhesive sheet were bonded and laminated using a hand roller to prepare a laminated body having a thickness of 0.5 mm. Using this laminate as a sample, a viscoelasticity measuring device (Discovery HR-2, manufactured by TA instrument) was used to apply shear stress to a parallel plate with a diameter of 8 mm so as to have a strain of 200% in an environment of 23 ° C. and 50%. Immediately after the application and after continuing to apply the shear stress, the stress was measured after 10 minutes.
Next, the applied shear stress was released, the shear stress was set to 0 kPa, and the strain when left for 10 minutes was measured. From the obtained strain, the restoration rate (%) was calculated based on the following formula.
Restoration rate (%) = (strain when left for 200-10 minutes) / 200

(Adhesive force)
One release sheet of the pressure-sensitive adhesive sheet is peeled off from the pressure-sensitive adhesive layer, and a polyethylene terephthalate (PET) film (Toyobo Ester (registered trademark) film E5100: manufactured by Toyobo Co., Ltd., thickness 50 μm) is attached to the surface of the pressure-sensitive adhesive layer, and then the other release sheet is attached. Was peeled off from the adhesive layer, and the adhesive layer surface was pressure-bonded to a polyimide film (Capton (registered trademark) 200 V: manufactured by Toyobo, 50 μm in thickness) by reciprocating a 2 kg roller twice.
One hour after laminating, it was cut out to a size of 25 mm in width and 150 mm in length, and according to the method of JIS Z 0237 (2009), a precision universal testing machine "AUTOGRAPH (registered trademark) AGS-1kNX, 50N load cell" manufactured by Shimadzu Corporation was used. The adhesive strength of the adhesive layer on the polyimide film was measured under the conditions of a peeling speed of 0.5 mm / s and a peeling angle of 180 ° in an environment of 23 ° C. and 50%.

(Repeated bending test)
One release sheet of the pressure-sensitive adhesive sheet is peeled off from the pressure-sensitive adhesive layer, and a polyethylene terephthalate (PET) film (Toyobo ester (registered trademark) film E5100: manufactured by Toyobo Co., Ltd., thickness 50 μm) is attached to the surface of the pressure-sensitive adhesive layer, and then the other release sheet is attached. Was peeled off from the adhesive layer, and the adhesive layer surface was pressure-bonded to a polyethylene terephthalate (PET) film (Diafoil (registered trademark) T330E: manufactured by Mitsubishi Chemical, thickness 150 μm) by reciprocating a 2 kg roller twice.
The obtained test piece for bending test is cut into a size of 25 mm in width and 90 mm in length, and both short sides are endurance tester (manufactured by Yuasa System Equipment Co., Ltd., surface body no-load U-shaped expansion / contraction tester, "DLDM111LH". ), A polyethylene terephthalate (PET) film having a thickness of 150 μm is fixed so as to bend with the film side as the outside, and the film is bent 200,000 times at a bending diameter (inner diameter / diameter) of 5 mm and a reciprocating speed of 60 spm (bending 60 times per minute). rice field. The test piece taken out from the testing machine was visually observed and evaluated according to the following criteria.
〇: There is no floating or peeling between the polyester film and the adhesive layer, and there are no cracks.
X: There is floating or peeling between the polyester film and the adhesive layer, or there are cracks.

<Manufacturing of copolymer>
(Synthesis Example 1: Copolymer No. A)
BA (1742.0 g), AA (3.6 g), HBA (54.0 g), AIBN (87.6 mg), AcOEt (1340 g) were charged into a flask equipped with an argon gas introduction tube and a stirrer, and argon was replaced. After that, BTEE (400 mg) was added, and the mixture was reacted at 60 ° C. for 24 hours to polymerize.

After completion of the reaction, AcOEt was added to the reaction solution to obtain copolymer No. A copolymer solution containing A was obtained. The obtained copolymer No. The Mw of A was 894,000, the PDI was 2.06, and the solid content of the solution was 20.1% by mass.

(Synthesis Examples 2 to 6: Copolymers No. B to F)
Copolymer No. In the same manner as in the production method of A, the copolymer No. B to F were prepared. 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. Table 3 shows the composition, Mw, PDI, and glass transition temperature of each copolymer.

(Synthesis Example 7: Copolymer No. G)
BA (364.5 g), ACMO (67.5 g), AA (13.5 g), HBA (4.5 g), AcOEt (276.5 g) in a flask equipped with an argon gas introduction tube, a dropping funnel and a stirrer. Was charged, replaced with argon, and then heated to 80 ° C. A solution of AIBN (197.1 mg) in AcOEt (45 g) was added over 2 hours, and the mixture was further reacted for 4 hours to polymerize.
After completion of the reaction, AcOEt was added to the reaction solution to obtain copolymer No. A copolymer solution containing F was obtained. The obtained copolymer No. The Mw of F was 873,000, the PDI was 6.48, and the solid content of the solution was 20.0% by mass.

(Synthesis Example 8: Copolymer No. H)
Copolymer No. In the same manner as in the production method of G, the copolymer No. H was prepared. Table 2 shows the raw material monomers used, the azo-based polymerization initiator, the solvent, the reaction conditions, and the polymerization rate. In addition, Table 3 shows the composition of the copolymer, Mw, PDI, and the glass transition temperature.

<Manufacturing of adhesive composition>
(Adhesive Composition No. 1)
The copolymer No. 1 obtained in Synthesis Example 1 0.076 parts by mass of a cross-linking agent (Duranate (registered trademark) TPA-100) and 0.023 parts by mass of a cross-linking accelerator (Neostan (registered trademark) U-810) with respect to 100 parts by mass of the copolymer component of A. Parts, 0.33 parts by mass of the cross-linking retarder (acetylacetone), 30 parts by mass of the tackifier (FTR (registered trademark) 6100), AcOEt were added, and the mixture was stirred to obtain the pressure-sensitive adhesive composition No. I got 1.

(Adhesive Composition Nos. 2 to 16)
Adhesive Composition No., except that the formulation was changed as shown in Table 4. In the same manner as in No. 1, the adhesive composition No. 2 to 16 were prepared.

ＴＥＴＲＡＤ（登録商標）−Ｃ：三菱ガス化学社製、１，３−ビス（Ｎ，Ｎ−ジグリシジルアミノエチル）シクロヘキサン（エポキシ基量；９．７６ｍｍｏｌ／ｇ）
ＴＰＡ−１００：旭化成社製、デュラネート（登録商標）ＴＰＡ−１００（ヘキサメチレンジイソシアネートのイソシアヌレート体（ＮＣＯ％；２３．１質量％））
Ｕ−８１０：日東化成社製、ネオスタン（登録商標）Ｕ−８１０（ジオクチル錫）
ＡｃＡｃ；アセチルアセトン
ＦＴＲ６１００：三井化学製、ＦＴＲ（登録商標）６１００（芳香族系炭化水素樹脂）
ＦＴＲ８１２０：三井化学製、ＦＴＲ（登録商標）８１２０（芳香族系炭化水素樹脂）

TETRAD®-C: Mitsubishi Gas Chemical Company, Ltd., 1,3-bis (N, N-diglycidylaminoethyl) cyclohexane (epoxy group amount; 9.76 mmol / g)
TPA-100: Duranate (registered trademark) TPA-100 manufactured by Asahi Kasei Corporation (isocyanurate form of hexamethylene diisocyanate (NCO%; 23.1% by mass))
U-810: Neostan (registered trademark) U-810 (Dioctyl tin) manufactured by Nitto Kasei Co., Ltd.
AcAc; Acetylacetone FTR6100: Mitsui Chemicals, FTR® 6100 (aromatic hydrocarbon resin)
FTR8120: Mitsui Chemicals, FTR® 8120 (aromatic hydrocarbon resin)

<Sheet-like adhesive>
Using a release sheet (polyethylene terephthalate (PET) film with mold release treatment on the surface, Clean Sepa (registered trademark) HY-S10: manufactured by Higashiyama Film, thickness 38 μm), the surface that has undergone mold release treatment is on the inside. A container having a length of 70 mm, a width of 70 mm, and a height of 20 mm was produced in such a manner. Each adhesive composition is added to this container so that the film thickness after drying is 1.0 mm, dried at 60 ° C. for 12 hours using a constant temperature dryer, and then taken out from the container to prepare a sheet-like adhesive material. bottom. The evaluation results of each sheet-shaped adhesive are shown in Table 5.

As shown in Table 5, the sheet-like adhesive No. 1 to 13 are cured products of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a reactive functional group and a cross-linking agent, and the (meth) acrylic copolymer is subjected to living radical polymerization. It is obtained, and the pressure-sensitive adhesive has a predetermined Young ratio and a retention rate of elastic ratio at the time of shrinkage.

<Manufacturing of adhesive sheet>
A film after drying using a baker-type applicator on the release surface of the first release sheet (PET film with a release treatment on the surface, Clean Sepa (registered trademark) HY-S10: manufactured by Higashiyama Film, thickness 38 μm). After applying the pressure-sensitive adhesive composition so as to have a thickness of 25 μm, it was dried at 120 ° C. for 3 minutes using a constant temperature dryer. Next, the adhesive layer formed on the first release sheet was coated with the second release sheet (PET film whose surface was subjected to a mold release treatment, Clean Sepa (registered trademark) HY-S10: manufactured by Higashiyama Film, thickness 38 μm). After the release surfaces were bonded together, aging was performed at 40 ° C. for 3 days to prepare an adhesive layer sandwiched between two release sheets. The evaluation results of each adhesive sheet are shown in Table 6.

As shown in Table 6, the adhesive sheet No. In 21, 22, 23 and 25, the adhesive layer is the sheet-like adhesive No. It is made up of 4, 9, 11 and 13. Even when these adhesive sheets were repeatedly bent, the occurrence of appearance defects such as cracks and waviness was suppressed without the occurrence of floating or peeling at the interface between the layered layer and the flexible member at the bent portion.

In the adhesive material of the present invention, one flexible member (for example, a functional sheet member) constituting a flexible display that can be repeatedly bent and extended and used is bonded to another flexible member (for example, a display element). Can be used to

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 30: Flexible laminated member 32: Cover film 32a: Cover film base material 32b: Hard coat layer 34: Polarizing film

Claims (9)

An adhesive material used to bond one flexible member to another.
The pressure-sensitive adhesive is a cured product of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a reactive functional group and a cross-linking agent.
The (meth) acrylic copolymer is obtained by living radical polymerization, and its molecular weight distribution (Mw / Mn) is 3.0 or less.
Shear storage modulus at 23 ° C. of the adhesive material is a ^{0.8 × 10 4 Pa~30 × 10 4} Pa,
The Young's modulus of the adhesive material is 10 kPa to 1000 kPa.
When the adhesive material was stretched until the tensile stress reached 50 kPa and then the shrinkage test for releasing the tensile stress was repeated 10 times, the ratio of the elastic modulus at contraction of the 10th time to the elastic modulus at contraction of the first time was determined. An adhesive material having a content of 60% or more. The pressure-sensitive adhesive according to claim 1, wherein the (meth) acrylic copolymer has a weight average molecular weight of 200,000 to 2 million. The pressure-sensitive adhesive according to claim 1 or 2, wherein the reactive functional group is a carboxy group and / or a hydroxy group. The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the cross-linking agent has an epoxy group and / or an isocyanate group. An adhesive sheet having an adhesive layer used for bonding one flexible member and another flexible member, and a flexible sheet member attached to at least one surface of the adhesive layer.
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive material according to any one of claims 1 to 4. 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 according to claim 5, 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 any one of claims 1 to 4. The flexible laminated member according to claim 7, wherein at least one of the first flexible member and the second flexible member is a display element. An apparatus comprising the flexible laminated member according to claim 7 or 8.

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