CN117625051A

CN117625051A - Double-sided adhesive sheet

Info

Publication number: CN117625051A
Application number: CN202311095583.6A
Authority: CN
Inventors: 定司健太; 藤田卓也; 箕浦一树; 尾崎智行; 几波勇人
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2022-08-31
Filing date: 2023-08-29
Publication date: 2024-03-01
Also published as: JP2024033676A

Abstract

The present invention relates to a double-sided adhesive sheet. The invention provides a double-sided adhesive sheet which has excellent impact resistance and is not easy to generate adhesive paste protrusion. The double-sided adhesive sheet (1) has a base material (2) and adhesive layers (3, 4) provided on at least one surface of the base material (2). The thickness of the adhesive layers (3, 4) is 12 μm or more. The thickness of the double-sided adhesive sheet (1) is 60 μm or more. In the following compression test, the reduction rate of the thickness after 1000 th compression was 30% or less, compression test: the double-sided adhesive sheet (1) was laminated to a thickness of 1mm or more in a size of 5mm by 5mm, and the operation of applying a load of 1.5MPa in the thickness direction and then releasing the load was repeated 1000 times.

Description

Double-sided adhesive sheet

Technical Field

The present invention relates to a double-sided adhesive sheet.

Background

Various performances such as high adhesion are required for an adhesive sheet used for a portable electronic device such as a mobile phone, a digital camera, and a PDA (portable information terminal). For example, in addition to having high adhesion, there is also a need for not to peel off even in the case of applying an impact, and not to apply a strong impact to a member

Patent documents 1 and 2 disclose a double-sided adhesive tape having an adhesive layer formed of an adhesive composition containing a specific filler as a double-sided adhesive sheet capable of exhibiting excellent impact resistance.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-128454

Patent document 2: japanese patent application laid-open No. 2021-24907

Disclosure of Invention

Problems to be solved by the invention

When attempting to further improve the impact resistance of the adhesive sheet, it is considered to improve the softness of the adhesive layer. However, when the pressure-sensitive adhesive layer has high flexibility, the pressure-sensitive adhesive layer tends to protrude from the adhesive region, for example, when the pressure-sensitive adhesive sheet is repeatedly bent, and there is a problem that so-called sticking out occurs.

The present invention has been made in view of such circumstances, and an object thereof is to provide a double-sided pressure-sensitive adhesive sheet which is excellent in impact resistance and is less likely to cause sticking out.

Means for solving the problems

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a double-sided adhesive sheet having a specific structure and properties can provide a double-sided adhesive sheet which is excellent in impact resistance and less prone to occurrence of sticking out. The present invention has been completed based on these findings.

That is, the present invention provides a double-sided adhesive sheet having a substrate and an adhesive layer provided on at least one face of the substrate, wherein,

the thickness of the adhesive layer is 12 μm or more,

The thickness of the double-sided adhesive sheet is 60 μm or more,

in the following compression test, the reduction rate of the thickness after 1000 th compression was 30% or less,

compression test:

the double-sided adhesive sheet was laminated to a thickness of 1mm or more in a size of 5mm×5mm, and the operation of applying a load of 1.5MPa in the thickness direction and then releasing the load was repeated 1000 times.

The storage modulus of the base material is preferably 2MPa or more, and the ratio of the thickness of the base material to the thickness of the double-sided adhesive sheet is preferably 10% or more.

The thickness of the substrate is preferably 20 μm or more.

The Z-axis adhesive strength of the adhesive layer at 23℃is preferably 0.6MPa or more.

The adhesive constituting the adhesive layer preferably contains at least an acrylic adhesive, a polyester adhesive, a rubber adhesive, or a urethane adhesive.

The double-sided adhesive sheet is preferably a double-sided adhesive sheet for fixing members in electrical and electronic equipment to each other.

In addition, the present invention provides an electric and electronic apparatus having the double-sided adhesive sheet that fixes members to each other through two adhesive faces.

Effects of the invention

According to the double-sided adhesive sheet of the present invention, a double-sided adhesive sheet having excellent impact resistance and less prone to occurrence of sticking out can be provided. Therefore, for example, when used in a portable electronic device, breakage and peeling are less likely to occur even when the adherend is deformed by a falling impact, and the adhesive layer is less likely to protrude from the adhesive region even when repeatedly bent.

Drawings

Fig. 1 is a schematic cross-sectional view showing one embodiment of the double-sided adhesive sheet of the present invention.

Fig. 2 is a schematic cross-sectional view for explaining an evaluation method of the compression test.

Description of the reference numerals

1 double-sided pressure-sensitive adhesive sheet

2 substrate

3. 4 adhesive layer

5. 6 Release liner

7 evaluation sample

8PET film

9 working table

Detailed Description

[ double-sided adhesive sheet ]

The double-sided adhesive sheet according to one embodiment of the present invention includes a substrate and adhesive layers provided on both sides of the substrate.

Fig. 1 is a schematic cross-sectional view showing an embodiment of the double-sided adhesive sheet of the present invention. As shown in fig. 1, the double-sided adhesive sheet 1 has a substrate 2, an adhesive layer 3 provided on one face of the substrate 2, and an adhesive layer 4 provided on the other face of the substrate 2. A release liner 5 and a release liner 6 may be provided on the surfaces of the adhesive layer 3 and the adhesive layer 4, respectively.

The thickness of the double-sided adhesive sheet of the present invention is 60 μm or more, preferably 100 μm or more. The above thickness of 60 μm or more is excellent in impact resistance. The thickness is preferably 500 μm or less, more preferably 400 μm or less. When the thickness is 500 μm or less, the sticking out of the paste is less likely to occur. In addition, the workability is excellent. The thickness of the double-sided adhesive sheet refers to the thickness from one adhesive surface to the other, that is, the thickness of the adherend, and does not include a release liner.

In the following compression test, the reduction ratio of the thickness of the double-sided adhesive sheet after 1000 th compression of the present invention is 30% or less, preferably 28% or less, more preferably 24% or less, still more preferably 20% or less, and the compression test: the double-sided adhesive sheet was laminated to a thickness of 1mm or more in a size of 5mm×5mm, and the operation of applying a load of 1.5MPa in the thickness direction and then releasing the load was repeated 1000 times. By the above reduction ratio being 30% or less, the thickness of the double-sided adhesive sheet is less likely to change even when subjected to repeated bending, and the occurrence of sticking out is less likely to occur. The reduction rate is, for example, 1% or more, preferably 5% or more, and may be 10% or more from the viewpoint of excellent impact resistance.

In the compression test, an adhesive sheet laminate obtained by laminating a double-sided adhesive sheet (adhesive body without release liner) to a thickness of 1mm or more in a size of 5mm×5mm was evaluated and calculated according to the following formula. The pressure-sensitive adhesive sheet laminate may be obtained by laminating the pressure-sensitive adhesive sheet laminate to a thickness of 1mm or more, and when the thickness is 1mm or more, the lamination of the next double-sided pressure-sensitive adhesive sheet is not performed. The above-mentioned thickness reduction ratio can be appropriately designed by adjusting the thickness ratio of the base material, the storage modulus, the thickness ratio of the adhesive layer, and the like in the double-sided adhesive sheet.

Thickness reduction rate (%) = (initial thickness-thickness after test)/initial thickness×100

The ratio of the thickness of the base material to the total thickness of the double-sided adhesive sheet (thickness of the adhesive body) is preferably 10% or more, more preferably 20% or more, and still more preferably 30% or more. When the above ratio is 10% or more, the thickness reduction ratio can be further reduced. In addition, the easy-to-detach property (reworkability) of the double-sided adhesive sheet, which can be easily detached at any timing by a simple method, is excellent. The above ratio is preferably 80% or less, more preferably 65% or less, and further preferably 50% or less. When the above ratio is 80% or less, the thickness of the adhesive layer becomes relatively thick, and the impact resistance is more excellent.

The ratio of the total thickness of the pressure-sensitive adhesive layer to the total thickness of the double-sided pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive body) is preferably 20% or more, more preferably 35% or more, and still more preferably 50% or more. When the above ratio is 20% or more, impact resistance is more excellent. The above ratio is preferably 90% or less, more preferably 80% or less, and further preferably 70% or less. When the ratio is 90% or less, the thickness reduction ratio can be further reduced, and reworkability is excellent.

The ratio of the total thickness of the single-sided pressure-sensitive adhesive layer to the total thickness of the double-sided pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive body) is preferably 17% or more, more preferably 20% or more, and still more preferably 25% or more. When the above ratio is 17% or more, impact resistance is more excellent. The above ratio is preferably 45% or less, more preferably 40% or less, and further preferably 35% or less. When the ratio is 45% or less, the thickness reduction ratio can be further reduced, and reworkability is excellent.

The impact absorption amount of the double-sided pressure-sensitive adhesive sheet is preferably 0.4J or more, more preferably 0.5J or more, still more preferably 0.6J or more, still more preferably 0.7J or more, and particularly preferably 0.8J or more. When the impact absorption amount is 0.4J or more, the impact resistance is more excellent. In addition, from the viewpoint of excellent impact resistance of the double-sided adhesive sheet, the double-sided adhesive sheet preferably satisfies that the adhesive layer contains at least one of a filler and a total thickness of the adhesive layer in the double-sided adhesive sheet is 150 μm or more.

(substrate)

The base material is an element that functions as a support in the double-sided adhesive sheet. The substrate may be a single layer, or may be a laminate of substrates of the same kind or different kinds.

The storage modulus of the substrate is preferably 2MPa or more, more preferably 5MPa or more, and may be 1000MPa or more. When the storage modulus is 2MPa or more, the thickness reduction ratio can be further reduced. The storage modulus is measured when dynamic viscoelasticity is performed at a frequency of 1Hz in a room temperature environment.

The maximum value of the loss tangent tan delta of the substrate at 23 ℃ and a frequency of 10kHz to 3.5MHz is preferably 0.83 or less, more preferably 0.80 or less, further preferably 0.75 or less, further preferably 0.70 or less, further preferably 0.65 or less, further preferably 0.60 or less, and particularly preferably 0.50 or less. The maximum value of tan δ is, for example, 0.20 or more, preferably 0.25 or more, more preferably 0.30 or more, and still more preferably 0.35 or more, from the viewpoint of further excellent impact resistance. In the case where the substrate is composed of a plurality of layers (laminate), the maximum value of tan δ is preferably 0.83 or less for all the substrates. The range of the above-mentioned frequency is a frequency corresponding to the falling impact, and when the maximum value of tan δ in the above-mentioned frequency region is 0.83 or less, the impact resistance is excellent and the reworkability is also excellent.

Examples of the substrate include porous materials such as plastic substrates (e.g., plastic films), papers, cloths, and nonwoven fabrics, nets, and foam sheets. As the base material, a plastic base material (particularly, a plastic film) is preferable. The base material is preferably a non-foamed sheet.

Examples of the resin constituting the plastic base material include: polyolefin resins such as polyethylene (low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, etc.), polypropylene (random copolymer polypropylene, block copolymer polypropylene, homo polypropylene, etc.), polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc.; polyurethane resin; rubber-based resins (natural rubber-based, synthetic rubber-based, mixed systems thereof, etc.): polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, polybutylene terephthalate (PBT), and the like; a polycarbonate; polyimide; polyether ether ketone; a polyetherimide; polyamides such as aromatic polyamides and wholly aromatic polyamides; polyphenylene sulfide; fluorine-containing resin; polyvinyl chloride; polyvinylidene chloride; a cellulose resin; polysiloxane resins, and the like. The resin may be used alone or in combination of two or more.

The resin may be a thermoplastic resin or a thermosetting resin, and is preferably a thermoplastic resin. The thermoplastic resin may be a thermoplastic elastomer such as a thermoplastic polyurethane elastomer. The thermoplastic polyurethane elastomer (TPU) includes a hard phase (hard segment) and a soft phase (soft segment).

Among these, the base material preferably contains at least a polyurethane resin, a rubber resin, a polyester resin, or a polyolefin resin, from the viewpoint of facilitating the storage modulus to be within the above range.

The polyurethane resin is usually obtained by reacting a polyisocyanate, a long-chain polyol, a chain extender (chain extender), and, if necessary, another isocyanate-reactive compound.

The polyisocyanate is a compound having two or more isocyanate groups in the molecule. Examples of the polyisocyanate include; aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, and the like. The polyisocyanates mentioned above may also be exemplified by: dimers, trimers, reaction products or polymers (e.g., dimers, trimers, reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, etc.) obtained from the above aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate and/or aromatic aliphatic polyisocyanate. The polyisocyanate may be used alone or in combination of two or more.

Examples of the long-chain polyol include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and polyacrylic polyols. The number average molecular weight of the long-chain polyol is usually 500 or more, preferably 500 to 10000, more preferably 600 to 6000, still more preferably 800 to 4000. The long-chain polyol may be used alone or in combination of two or more.

The chain extender used in the production of polyurethane elastomers may be, for example, a low molecular weight polyol, a polyamine, or the like. The molecular weight of the chain extender is generally less than 500, preferably 300 or less. The chain extender may be used alone or in combination of two or more.

From the viewpoint of easily making the maximum value of tan δ within the above range, the polyurethane resin preferably includes a polyurethane resin (polyether polyol polyurethane resin) containing a polyether polyol as the long chain polyol. Further, a polyurethane resin (polyester polyol polyurethane resin) containing a polyester polyol as the long-chain polyol may be included.

The polyurethane resin preferably contains a hard polyurethane resin from the viewpoint of easily adjusting the storage modulus of the base material within the above range. When two or more kinds of polyurethane resins are contained, the hard polyurethane resin is the polyurethane resin having the highest hardness. The hardness D of the hard polyurethane resin is preferably 30 or more, more preferably 40 or more. The hardness D of the hard polyurethane resin is, for example, 50 or less.

The polyurethane resin may contain a polyurethane resin (soft polyurethane resin) having a lower hardness than the hard polyurethane, together with the hard polyurethane. The shore a hardness of the soft polyurethane resin is preferably 70 or less, and more preferably 66 or less. The shore a hardness of the soft polyurethane resin is preferably 40 or more, and more preferably 50 or more.

From the viewpoint of easy adjustment of the storage modulus of the base material within the above range, the proportion of the hard polyurethane resin in the polyurethane resin is preferably greater than 50 mass%, more preferably 60 mass% or more, still more preferably 70 mass% or more, and even more preferably 80 mass% or more, relative to the total amount (100 mass%) of the polyurethane resin. The proportion is not particularly limited, and may be 99 mass% or less, or 95 mass% or less.

The base material may contain other resins such as a rubber resin in addition to the polyurethane resin. From the viewpoint of easy adjustment of the maximum value of tan δ within the above range, the ratio of the urethane resin in the base material to the total of the urethane resin and the rubber resin is preferably more than 50 mass%, more preferably 60 mass% or more, still more preferably 70 mass% or more, and still more preferably 80 mass% or more. The proportion is not particularly limited, and may be 99% by mass or less and may be 90% by mass or less.

The base material may be produced by a known or conventional method, and examples thereof include extrusion molding, inflation molding, T-die casting molding, calender roll molding, and the like.

The proportion of the thermoplastic resin (particularly, one or more resins selected from the group consisting of polyurethane-based resins, rubber-based resins, and polyolefin-based resins) in the base material is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to the total amount (100% by mass) of the base material.

The base material may contain various additives such as fillers (inorganic fillers, organic fillers, etc.), colorants (pigments, dyes), dispersants (surfactants, etc.), antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, etc. The blending proportion of each additive is less than about 30 mass% (for example, less than about 20 mass%, typically less than about 10 mass%) with respect to 100 mass% of the total mass of the above-described base material.

The substrate may include an auxiliary layer. Examples of the auxiliary layer include a colored layer, a reflective layer, an undercoat layer, and an antistatic layer provided on the surface of the base material.

Physical treatments such as corona discharge treatment, plasma treatment, sanding treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, and ionizing radiation treatment may be applied to the surface of the substrate in order to improve adhesion to the adhesive layer, retention property, and the like; chemical treatments such as chromic acid treatment; surface treatment such as easy adhesion treatment with a coating agent (primer). The entire surface of the substrate is preferably subjected to a surface treatment for improving adhesion.

The thickness of the substrate is not particularly limited, but is preferably 20 μm or more, more preferably 30 μm or more, further preferably 40 μm or more, and particularly preferably 50 μm or more. When the thickness is 20 μm or more, reworkability is more excellent. The thickness is not particularly limited, and is, for example, 400 μm or less, preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 100 μm or less.

(adhesive layer)

The pressure-sensitive adhesive layers provided on both sides of the substrate in the double-sided pressure-sensitive adhesive sheet may be the same pressure-sensitive adhesive layer or may be pressure-sensitive adhesive layers having different compositions, thicknesses, physical properties, and the like. The pressure-sensitive adhesive layer provided on one surface of the substrate may be a single layer or may be a plurality of layers having the same composition or different layers having different thicknesses, physical properties, or the like.

As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, known or conventional pressure-sensitive adhesives can be used, and examples thereof include: acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixed systems thereof, and the like), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, fluorine-containing adhesives, styrene adhesives, and the like. Among them, acrylic adhesives, polyester adhesives, rubber adhesives, and urethane adhesives are preferable as the adhesive constituting the adhesive layer in terms of adhesion, weather resistance, cost, and ease of designing the adhesive. The binder may be used alone or in combination of two or more.

The acrylic adhesive contains an acrylic polymer as a base polymer. The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth) acryloyl group in a molecule) as a monomer component constituting the polymer. That is, the acrylic polymer contains a structural unit derived from an acrylic monomer. The acrylic polymer may be used alone or in combination of two or more. The acrylic polymer may contain only one kind of acrylic monomer as a monomer component, or may contain two or more kinds. In the present specification, "(meth) acrylic acid" means "acrylic acid" and/or "methacrylic acid" ("acrylic acid" and "methacrylic acid" either or both), and the other is the same.

In the present specification, the base polymer means a main component of polymer components in the adhesive constituting the adhesive layer, for example, a polymer component having a content of more than 50 mass%. The content of the base polymer in the pressure-sensitive adhesive layer is preferably 60 mass% or more, more preferably 70 mass% or more, based on 100 mass% of the total pressure-sensitive adhesive layer.

The acrylic polymer is preferably a polymer having the highest content of structural units derived from (meth) acrylic esters in terms of mass ratio. Examples of the (meth) acrylate include hydrocarbon group-containing (meth) acrylates. Examples of the hydrocarbon group-containing (meth) acrylate include: alkyl (meth) acrylates having a linear aliphatic hydrocarbon group or a branched aliphatic hydrocarbon group, (meth) acrylates having an alicyclic hydrocarbon group such as cycloalkyl (meth) acrylate, and (meth) acrylates having an aromatic hydrocarbon group such as aryl (meth) acrylate. The hydrocarbon group-containing (meth) acrylate may be used alone or in combination of two or more.

Examples of the alkyl (meth) acrylate include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate.

Among these alkyl (meth) acrylates, preferred are alkyl (meth) acrylates having a linear aliphatic hydrocarbon group or a branched aliphatic hydrocarbon group having 1 to 20 carbon atoms (preferably 2 to 12 carbon atoms, more preferably 4 to 10 carbon atoms). When the number of carbon atoms is within the above range, the glass transition temperature of the acrylic polymer can be easily adjusted, and the adhesiveness can be easily improved.

Examples of the alicyclic hydrocarbon group-containing (meth) acrylate include: (meth) acrylic esters having a monocyclic aliphatic hydrocarbon ring such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate; (meth) acrylic esters having a double-ring aliphatic hydrocarbon ring such as isobornyl (meth) acrylate; and (meth) acrylic esters having an aliphatic hydrocarbon ring having three or more rings, such as tetrahydrodicyclopentadiene (meth) acrylate, tetrahydrodicyclopentadiene oxyethyl (meth) acrylate, tetrahydrotricyclopentadienyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate.

Examples of the (meth) acrylic acid ester having an aromatic hydrocarbon group include phenyl (meth) acrylate and benzyl (meth) acrylate.

In order to properly exhibit basic properties such as adhesiveness obtained from the hydrocarbon group-containing (meth) acrylate in the pressure-sensitive adhesive layer, the proportion of the hydrocarbon group-containing (meth) acrylate in the total monomer components constituting the acrylic polymer is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and may be 80% by mass or more, 90% by mass or more, or 95% by mass or more, relative to the total amount (100% by mass) of the total monomer components. The proportion may be 99.9% by mass or less, or 98% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less, from the viewpoint of obtaining the effect of the other monomer component by copolymerizing the other monomer component.

The acrylic polymer may contain a structural unit derived from another monomer component copolymerizable with the hydrocarbon group-containing (meth) acrylate for the purpose of improving the cohesive force, introducing a crosslinking point, and the like. Examples of the other monomer component include: and polar group-containing monomers such as hydroxyl group-containing monomers, nitrogen atom-containing monomers, carboxyl group-containing monomers, acid anhydride monomers, ketone group-containing monomers, alkoxysilyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers. The other monomer components may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4-hydroxymethylcyclohexyl (meth) acrylate, and the like.

Examples of the nitrogen atom-containing monomer include amide group-containing monomers, amino group-containing monomers, cyano group-containing monomers, and monomers having a nitrogen atom-containing ring. Examples of the amide group-containing monomer include: (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol propane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and the like. Examples of the amino group-containing monomer include: aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and the like. Examples of the cyano group-containing monomer include: acrylonitrile, methacrylonitrile. Examples of the monomer having a nitrogen atom-containing ring include: n-vinyl-2-pyrrolidone, N-methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinylOxazole, N-vinylmorpholine, N-vinylcaprolactam, N- (meth) acryloylmorpholine and the like.

Examples of the carboxyl group-containing monomer include: acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. Examples of the acid anhydride monomer include maleic anhydride and itaconic anhydride.

Examples of the ketone group-containing monomer include: diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate, and the like.

Examples of the alkoxysilyl group-containing monomer include: 3- (meth) acryloxypropyl trimethoxysilane, 3- (meth) acryloxypropyl triethoxysilane, 3- (meth) acryloxypropyl methyldimethoxysilane, 3- (meth) acryloxypropyl methyldiethoxysilane, and the like.

Examples of the glycidyl group-containing monomer include: glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and the like.

Examples of the sulfonic acid group-containing monomer include: styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloxynaphthalene sulfonic acid.

Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

The total of the proportions of the polar group-containing monomers in the total monomer components (100 mass%) constituting the acrylic polymer is not particularly limited, but is preferably 0.1 mass% or more, more preferably 1 mass% or more, from the viewpoint of better effects due to the use of the polar group-containing monomers. In addition, from the viewpoint of obtaining an adhesive layer having moderate flexibility, the total of the above proportions is preferably 10 mass% or less, more preferably 8 mass% or less.

Other monomers may be contained as the monomer component constituting the acrylic polymer. Examples of the other monomer include: vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α -methylstyrene, etc.), and vinyl toluene; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether, and the like.

The proportion of the other monomer in 100 mass% of the total monomer components constituting the acrylic polymer may be, for example, 0.05 mass% or more and 0.5 mass% or more. The proportion may be, for example, 20 mass% or less, 10 mass% or less, or 5 mass% or less, and may be substantially absent.

The weight average molecular weight (Mw) of the acrylic polymer is preferably 5X 10 ⁴ The above is more preferably 10×10 ⁴ The above is more preferably 20×10 ⁴ The above is particularly preferably 30×10 ⁴ The above. When the Mw is 5X 10 ⁴ In this way, an adhesive exhibiting good cohesiveness can be easily obtained. In addition, the Mw is preferably 500X 10 ⁴ The following is given. When the Mw is 500X 10 ⁴ In the following, since an adhesive exhibiting moderate fluidity (mobility of the polymer chain) is easily formed, reworkability is excellent.

The acrylic polymer may be obtained by polymerizing a composition containing at least an acrylic monomer. The polymerization methods are not particularly limited, and examples thereof include: solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, polymerization by irradiation with active energy rays (active energy ray polymerization), and the like. Among them, bulk polymerization, thermal polymerization, and active energy ray polymerization are preferable in terms of transparency of the adhesive layer, cost, and the like. The acrylic polymer obtained may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

The polyester-based adhesive contains a polyester-based resin as a base polymer. The polyester resin is a polymer containing a polyhydric alcohol and a polycarboxylic acid as monomer components constituting the polymer. That is, the polyester resin contains a structural unit derived from a polyhydric alcohol and a structural unit derived from a polycarboxylic acid. The polyester resin may be used alone or in combination of two or more.

Examples of the polycarboxylic acid include dicarboxylic acids and tri-or higher carboxylic acids. Examples of dicarboxylic acids include: aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, dimethylglutaric acid, adipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, sebacic acid, thiodipropionic acid, and diglycolic acid; dimer acids of unsaturated fatty acids; alicyclic dicarboxylic acids such as 1, 2-cyclopentanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 4-methyl-1, 2-cyclohexanedicarboxylic acid, norbornanedicarboxylic acid, and adamantanedicarboxylic acid; unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, and dodecenyl succinic anhydride; aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, phthalic acid, benzyl malonic acid, 2 '-biphenyl dicarboxylic acid, 4' -dicarboxydiphenyl ether, and naphthalene dicarboxylic acid; derivatives thereof, and the like. Examples of the derivative include carboxylate, carboxylic anhydride, carboxylic halide, and carboxylic ester. Examples of the tri-or higher carboxylic acid include: trimellitic acid, pyromellitic acid, adamantane tricarboxylic acid, trimesic acid, and the like. The polycarboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include dihydric alcohols and trihydric or higher polyhydric alcohols. Examples of the diol include: (poly) alkylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, and polytetramethylene glycol; aliphatic diols such as 1, 3-propanediol, 2-methyl-1, 3-propanediol, 2-dimethyl-1, 3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1, 3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, 2-methyl-1, 3-hexanediol, 2, 4-trimethyl-1, 6-hexanediol, 1, 8-octanediol, 1, 9-nonanediol, and 1, 10-decanediol; a dimer diol; alicyclic diols such as 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, and 2, 4-tetramethyl-1, 3-cyclobutanediol; and aromatic diols such as 4,4' -thiodiphenol, 4' -methylenediphenol, 4' -dihydroxydiphenyl, catechol, resorcinol, hydroquinone, 2, 5-naphthalene diol, paraxylene diol, and ethylene oxide and propylene oxide adducts thereof. The three or more polyols include: pentaerythritol, dipentaerythritol, tripentaerythritol, glycerol, trimethylolpropane, trimethylolethane, 1,3, 6-hexanetriol, adamantanamine and the like. The above-mentioned polyhydric alcohol may be used alone or in combination of two or more.

The total content of the dicarboxylic acid-derived structural units and the diol-derived structural units in the polyester resin is preferably 90 mass% or more, more preferably 95 mass% or more, still more preferably 98 mass% or more, and particularly preferably 99 mass% or more (for example, 99 to 100 mass%) based on 100 mass% of the total of the structural units derived from the monomers constituting the polyester resin.

The content of the structural unit derived from the polycarboxylic acid in the polyester resin is, for example, 0.5 equivalent or more, preferably 0.58 equivalent or more, more preferably 0.66 equivalent or more, still more preferably 0.83 equivalent or more, still more preferably 0.88 equivalent or more, and particularly preferably 0.95 equivalent or more per 1 equivalent of the polyol. The content is, for example, 2.0 equivalents or less, preferably 1.7 equivalents or less, more preferably 1.5 equivalents or less, still more preferably 1.2 equivalents or less, still more preferably 1.1 equivalents or less, and particularly preferably 1.05 equivalents or less per 1 equivalent of the polyol.

The equivalent ratio of the structural unit derived from the polycarboxylic acid to the structural unit derived from the polyhydric alcohol in the polyester-based resin is not particularly limited, and may be set to an appropriate equivalent ratio in consideration of the physical properties, the synthesis properties, and the like of the target polymer. When the equivalent ratio of the polycarboxylic acid is high, the polycarboxylic acid-based characteristics can be easily exhibited. In addition, when the equivalent ratio of the polyol is high, the characteristics based on the polyol can be easily exhibited.

In the polymerization of the monomer component, various general solvents can be used. Examples of the solvent include: esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; organic solvents such as ketones including methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of two or more.

The polymerization initiator, chain transfer agent, emulsifier, etc. used for radical polymerization of the monomer component are not particularly limited, and may be appropriately selected and used. The weight average molecular weight of the polymer may be controlled by the polymerization initiator, the amount of the chain transfer agent, and the reaction conditions, and the amount thereof may be appropriately adjusted according to the kind thereof.

As the polymerization initiator used for polymerization of the monomer component, a thermal polymerization initiator, a photopolymerization initiator (photoinitiator), or the like may be used depending on the kind of polymerization reaction. The polymerization initiator may be used alone or in combination of two or more.

The thermal polymerization initiator is not particularly limited, and examples thereof include: azo-based polymerization initiators, peroxide-based polymerization initiators (e.g., persulfates such as dibenzoyl peroxide, t-butyl peroxymaleate, and potassium persulfate), phenyl-substituted ethane-based initiators such as benzoyl peroxide, and hydrogen peroxide, and redox-based polymerization initiators. Among them, the azo-based polymerization initiator disclosed in Japanese patent application laid-open No. 2002-69411 is preferable. The azo-based polymerization initiator may be: 2,2 '-azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, dimethyl 2,2 '-azobis (2-methylpropionate), 4' -azobis (4-cyanovaleric acid), and the like. The amount of the thermal polymerization initiator to be used may be any amount as long as it is a usual amount, and may be selected from, for example, 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the monomer component.

The photopolymerization initiator is not particularly limited, and examples thereof include: benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, alpha-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzil photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, and the like. Furthermore, there may be mentioned: acyl phosphine oxide photopolymerization initiator and titanocene photopolymerization initiator. Examples of the benzoin ether photopolymerization initiator include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-1, 2-diphenylethane-1-one, anisoin methyl ether, and the like. Examples of the acetophenone photopolymerization initiator include: 2, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4- (tert-butyl) dichloroacetophenone, and the like. Examples of the α -ketol photopolymerization initiator include: 2-methyl-2-hydroxy propiophenone, 1- [4- (2-hydroxyethyl) phenyl ] -2-methylpropan-1-one, and the like. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime-type photopolymerization initiator include 1-phenyl-1, 2-propanedione-2- (O-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzil photopolymerization initiator include benzil. Examples of the benzophenone photopolymerization initiator include: benzophenone, benzoyl benzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α -hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzildimethyl ketal. Examples of the thioxanthone photopolymerization initiator include: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-diisopropylthioxanthone, dodecylthioxanthone, and the like. Examples of the acylphosphine oxide photopolymerization initiator include: 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like. Examples of the titanocene-based photopolymerization initiator include: bis (. Eta.5-2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) -titanium, and the like. The amount of the photopolymerization initiator to be used may be any amount as long as it is a usual amount, and may be selected, for example, from 0.01 to 5 parts by mass, preferably from 0.05 to 3 parts by mass, based on 100 parts by mass of the monomer component.

The acrylic polymer and the polyester resin may contain a structural part derived from the crosslinking agent. That is, the acrylic polymer and the polyester resin may be an acrylic polymer and a polyester resin obtained by crosslinking with the crosslinking agent. By using a crosslinking agent, a crosslinked structure can be formed in the acrylic polymer in the acrylic adhesive layer, and the gel fraction can be controlled. The crosslinking agent has a function of crosslinking polyesters with each other, and may function as a chain extender for polyester resins. When the above-mentioned crosslinking agent is used, a crosslinked structure of the base polymer is formed in the adhesive layer, and the cohesive force is improved. The crosslinking agent may be used alone or in combination of two or more.

The crosslinking agent is not particularly limited, and examples thereof include: isocyanate-based crosslinking agent, epoxy-based crosslinking agent, melamine-based crosslinking agent, peroxide-based crosslinking agent, urea-based crosslinking agent, metal alkoxide-based crosslinking agent, and metal chelate-based crosslinking agentA metal salt cross-linking agent, a carbodiimide cross-linking agent, a metal salt cross-linking agent,Oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, hydrazine-based crosslinking agents, polysiloxane-based crosslinking agents, silane-based crosslinking agents (silane coupling agents), and the like.

The content of the crosslinking agent is not particularly limited, but is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 15 parts by mass, and particularly preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the total amount of the monomer components constituting the acrylic polymer and/or the polyester resin.

The isocyanate-based crosslinking agent is a compound having an average of two or more isocyanate groups per molecule (polyfunctional isocyanate compound). Examples of the isocyanate-based crosslinking agent include: aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like.

Examples of the aliphatic polyisocyanate include: 1, 2-ethylene diisocyanate; butylene diisocyanate such as 1, 2-butylene diisocyanate, 1, 3-butylene diisocyanate, and 1, 4-tetramethylene diisocyanate; hexamethylene diisocyanate such as 1, 2-hexamethylene diisocyanate, 1, 3-hexamethylene diisocyanate, 1, 4-hexamethylene diisocyanate, 1, 5-hexamethylene diisocyanate, 1, 6-hexamethylene diisocyanate and 2, 5-hexamethylene diisocyanate; 2-methyl-1, 5-pentane diisocyanate, 3-methyl-1, 5-pentane diisocyanate, lysine diisocyanate, and the like.

Examples of the alicyclic polyisocyanate include: isophorone diisocyanate; cyclohexyl diisocyanate such as 1, 2-cyclohexyl diisocyanate, 1, 3-cyclohexyl diisocyanate, and 1, 4-cyclohexyl diisocyanate; cyclopentyl diisocyanate such as 1, 2-cyclopentyl diisocyanate and 1, 3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, 4' -dicyclohexylmethane diisocyanate.

Examples of the aromatic polyisocyanate include: 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4' -diphenylmethane diisocyanate, 2' -diphenylmethane diisocyanate, 4' -diphenyl ether diisocyanate, 2-nitrodiphenyl-4, 4' -diisocyanate, 2' -diphenylpropane-4, 4' -diisocyanate 3,3' -dimethyldiphenylmethane-4, 4' -diisocyanate, 4' -diphenylpropane diisocyanate, isophthalate diisocyanate, p-phenylene diisocyanate, naphthylene 1, 4-diisocyanate, naphthylene 1, 5-diisocyanate, 3' -dimethoxydiphenyl-4, 4' -diisocyanate, xylylene-1, 4-diisocyanate, xylylene-1, 3-diisocyanate, and the like.

Examples of the isocyanate-based crosslinking agent include: commercially available products such as trimethylolpropane/toluene diisocyanate adduct (trade name "Coronate L", manufactured by Tosoh Co., ltd.), trimethylolpropane/hexamethylene diisocyanate adduct (trade name "Coronate HL", manufactured by Tosoh Co., ltd.), and trimethylolpropane/xylylene diisocyanate adduct (trade name "Takenate D-110N", manufactured by Sanchio chemical Co., ltd.).

In the aqueous dispersion of the modified acrylic polymer produced by emulsion polymerization, an isocyanate-based crosslinking agent may not be used, but if necessary, an isocyanate-based crosslinking agent that has been blocked may be used because it reacts with water easily.

The content of the isocyanate-based crosslinking agent in the case of using the isocyanate-based crosslinking agent as the crosslinking agent is not particularly limited, but is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, based on 100 parts by mass of the total amount of the monomer components constituting the acrylic polymer and/or the polyester-based resin. The content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 5 parts by mass or less.

Examples of the epoxy-based crosslinking agent (polyfunctional epoxy compound) include: n, N '-tetraglycidyl m-xylylenediamine, diglycidyl aniline, 1, 3-bis (N, N' -diglycidyl aminomethyl) 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, sorbitol anhydride polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (2-hydroxyethyl) isocyanurate triglycidyl ester, resorcinol diglycidyl ether, bisphenol S diglycidyl ether, epoxy resins having two or more epoxy groups in the molecule, and the like. Further, examples of the epoxy-based crosslinking agent include commercial products such as "tetra C" (manufactured by mitsubishi gas chemical Co., ltd.).

The content of the epoxy-based crosslinking agent in the case of using the epoxy-based crosslinking agent as the crosslinking agent is not particularly limited, but is preferably more than 0 part by mass and 1 part by mass or less, more preferably 0.001 part by mass to 0.5 part by mass, still more preferably 0.002 part by mass to 0.2 part by mass, still more preferably 0.005 part by mass to 0.1 part by mass, still more preferably 0.008 part by mass to 0.1 part by mass, and particularly preferably 0.009 part by mass to 0.05 part by mass, relative to 100 parts by mass of the total amount of the monomer components constituting the acrylic polymer and/or the polyester resin.

The peroxide-based crosslinking agent may be used as long as it is a peroxide-based crosslinking agent that crosslinks a base polymer by heat generation of a radical active species, but in view of handleability and stability, it is preferable to use a peroxide having a 1-minute half-life temperature of 80 to 160 ℃, and more preferable to use a peroxide having a 1-minute half-life temperature of 90 to 140 ℃.

Examples of the peroxide-based crosslinking agent include: di (2-ethylhexyl) peroxydicarbonate (1-min half-life temperature: 90.6 ℃), di (4-t-butylcyclohexyl) peroxydicarbonate (1-min half-life temperature: 92.1 ℃), di (sec-butyl) peroxydicarbonate (1-min half-life temperature: 92.4 ℃), t-butyl peroxyneodecanoate (1-min half-life temperature: 103.5 ℃), t-hexyl peroxypivalate (1-min half-life temperature: 109.1 ℃), t-butyl peroxypivalate (1-min half-life temperature: 110.3 ℃), dilauroyl peroxide (1-min half-life temperature: 116.4 ℃), di (1-min half-life temperature: 117.4 ℃), 1, 3-tetramethylbutyl peroxide (1-min half-life temperature: 124.3 ℃), di (4-methylbenzoyl) (1-min half-life temperature: 128.2 ℃), dibenzoyl peroxide (1-min half-life temperature: 130.0 ℃), t-butyl peroxide (1-half-life temperature: 1-min half-life temperature: 109.1 ℃), 1-t-hexyl peroxide (1-t-hexane) and the like.

The half-life of the peroxide-based crosslinking agent is an index indicating the decomposition rate of the peroxide, and means the time for which the residual amount of the peroxide reaches half. The decomposition temperature for obtaining the half-life at any time and the half-life time at any temperature are described in the manufacturer's catalog, for example, in "organic peroxide catalog 9 th edition (5 months in 2003)" of the japanese oil company. The method for measuring the peroxide decomposition amount remaining after the reaction treatment may be, for example, by HPLC (high performance liquid chromatography). More specifically, for example, about 0.2g of the reaction-treated adhesive was taken out each time, immersed in 10ml of ethyl acetate, extracted with shaking at 120rpm at 25℃for 3 hours using a shaker, and then allowed to stand at room temperature for 3 days. Next, 10ml of acetonitrile was added thereto, and the mixture was shaken at 25℃and 120rpm for 30 minutes, and about 10. Mu.l of the extract obtained by filtration through a membrane filter (0.45 μm) was poured into HPLC for analysis, whereby the peroxide amount after the reaction treatment was obtained.

The content of the crosslinking agent in the case of using a peroxide-based crosslinking agent as the crosslinking agent is not particularly limited, but is preferably 2 parts by mass or less, more preferably 0.02 parts by mass to 2 parts by mass, and still more preferably 0.05 parts by mass to 1 part by mass, based on 100 parts by mass of the total amount of the monomer components constituting the acrylic polymer and/or the polyester-based resin.

The crosslinking agent may be an organic crosslinking agent or a polyfunctional metal chelate. The multifunctional metal chelate is a multifunctional metal chelate in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of the polyvalent metal atom include: al, cr, zr, co, cu, fe, ni, V, zn, in, ca, mg, mn, Y, ce, sr, ba, mo, la, sn, ti, etc. Examples of the atoms in the covalently or coordinately bonded organic compound include oxygen atoms, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

Among these, the isocyanate-based crosslinking agent is preferably contained. In addition, it is more preferable to include other crosslinking agents together with the isocyanate-based crosslinking agent. As the other crosslinking agent, an epoxy-based crosslinking agent is preferable. When such a crosslinking agent is used, an adhesive layer having more excellent adhesion even when it is thin can be produced by combining the acrylic polymer and/or the polyester-based resin (particularly, by combining the acrylic polymer and/or the polyester-based resin which are preferable).

Examples of the rubber-based adhesive include: a natural rubber-based adhesive; isoprene rubber, polyisobutylene rubber, butyl rubber, ethylene-propylene rubber, styrene-butadiene rubber, styrene-isoprene rubber, styrene-ethylene-propylene-styrene rubber, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene block copolymer, reclaimed rubber, modified products thereof, and the like. In addition, when the rubber-based adhesive is a copolymer, the adhesive may be either a block copolymer or a random copolymer.

Examples of the silicone-based adhesive include silicone rubber and silicone resin containing an organopolysiloxane as a main component, and an adhesive obtained by adding a crosslinking agent such as a silicone-based crosslinking agent or a peroxide-based crosslinking agent to these components and crosslinking and polymerizing them.

The adhesive layer may contain a tackifying resin. When the tackifier resin is contained, the adhesive layer tends to have better adhesion even if it is thin. When the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive and/or a polyester pressure-sensitive adhesive and a tackifying resin, the pressure-sensitive adhesive layer has excellent adhesion to an adherend and is less likely to peel off.

Examples of the tackifying resin include: phenolic tackifying resins, terpene tackifying resins, rosin tackifying resins, hydrocarbon tackifying resins, epoxy tackifying resins, polyamide tackifying resins, elastomeric tackifying resins, ketone tackifying resins, and the like. The tackifying resin may be used alone or in combination of two or more.

The phenolic tackifying resins include: terpene phenol resins, hydrogenated terpene phenol resins, alkyl phenol resins, rosin phenol resins. The terpene-phenol resin is a polymer containing terpene residues and phenol residues, and examples thereof include: copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins), and resins obtained by phenol modification of homopolymers or copolymers of terpenes (phenol modified terpene resins). Examples of terpenes constituting the terpene phenol resin include: mono-terpenes such as α -pinene, β -pinene, limonene (d-isomer, l-isomer, d/l-isomer (terpineol), etc.). The hydrogenated terpene phenol resin is a resin having a structure obtained by hydrogenating the terpene phenol resin. The alkylphenol resin is a resin (oleo-phenolic resin) obtained from alkylphenol and formaldehyde. Examples of the alkylphenol resins include novolac-type and resol-type alkylphenol resins. The rosin phenol resin is a phenol modified product of rosins or various rosin derivatives described later. The rosin phenol resin can be obtained, for example, by a method in which phenol is added to rosin or various rosin derivatives described later by an acid catalyst and subjected to thermal polymerization.

The terpene-based tackifying resins include: polymers of terpenes (typically monoterpenes) such as alpha-pinene, beta-pinene, d-limonene, l-limonene, terpineol and the like. The terpene polymer may be a terpene homopolymer or a terpene copolymer of two or more kinds. Examples of the terpene homopolymer include α -pinene polymer, β -pinene polymer, and terpineol polymer. The modified terpene-based tackifying resin is a resin obtained by modifying the terpene resin (modified terpene resin). Examples of the modified terpene resin include styrene modified terpene resins and hydrogenated terpene resins.

The rosin-based tackifying resin includes rosin-based and rosin derivative resins. Examples of the rosin include: unmodified rosins (raw rosins) such as gum rosin, wood rosin, tall oil rosin, and the like; modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, other chemically modified rosins, etc.) obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc., and the like. The rosin derivative resin may be a rosin derivative. Examples of the rosin derivative resin include: rosin esters such as unmodified rosin esters which are esters of unmodified rosin and alcohols, and modified rosin esters which are esters of modified rosin and alcohols; unsaturated fatty acid-modified rosins obtained by modifying rosins with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing carboxyl groups of rosins or various rosin derivatives described above; rosin or metal salts of various rosin derivatives described above. Specific examples of the rosin esters include methyl esters, triethylene glycol esters, glycerol esters, pentaerythritol esters, and the like of unmodified or modified rosin.

The hydrocarbon tackifying resins include: aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic/aromatic petroleum resins (styrene-olefin copolymers and the like), aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone indene resins and the like.

The content of the tackifying resin in the pressure-sensitive adhesive layer is not particularly limited, but is, for example, 1 part by mass or more (for example, 1 part by mass to 100 parts by mass), preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the total amount of the base polymer. When the content is 1 part by mass or more, the adhesive layer has more excellent adhesion even if it is thin. The content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less, from the viewpoint of excellent heat-resistant cohesive force.

The adhesive layer may or may not contain a filler. When the filler is contained, the adhesiveness of the adhesive layer when the double-sided adhesive sheet is intentionally peeled is reduced, and reworkability is further excellent. The filler may be used alone or in combination of two or more.

The filler may be a particulate organic material or an inorganic material. Examples of the material constituting the inorganic substance include: metals such as copper, silver, gold, platinum, nickel, aluminum, chromium, iron, stainless steel, and the like; metal oxides such as aluminum oxide, silicon oxide (silicon dioxide, silicon oxide), titanium oxide, zirconium oxide, zinc oxide, tin oxide, copper oxide, and nickel oxide; metal hydroxides and hydrated metal compounds such as aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, hydrotalcite, dawsonite, borax, and zinc borate; carbides such as silicon carbide, boron carbide, nitrogen carbide, and calcium carbide; nitrides such as aluminum nitride, silicon nitride, boron nitride, and gallium nitride; carbonates such as calcium carbonate; titanates such as barium titanate and potassium titanate; carbon substances such as carbon black, carbon tubes (carbon nanotubes), carbon fibers, and diamond; inorganic materials such as glass; and natural raw material particles such as volcanic sand, clay, sand and the like.

Examples of the material constituting the organic substance include: polystyrene, acrylic resins (e.g., polymethyl methacrylate), phenol resins, benzoguanamine resins, urea resins, polysiloxane resins, polyesters, polyurethanes, polyolefins (polymers containing one or more α -olefins as a monomer component; e.g., polyethylene such as LLDPE, LDPE, HDPE, polypropylene, etc.), polyamides (e.g., nylon, etc.), polyimides, polymers such as polyvinylidene chloride, etc.

The filler may be a filler having a hollow body structure. The hollow portion (the inner space of the hollow particles) of the filler having the hollow body structure may be in a vacuum state or may be filled with a medium. Examples of the medium include inert gases such as nitrogen and argon, air, and volatile solvents.

Among these fillers, fillers whose surface is composed of an organic or inorganic substance other than the base polymer type and fillers having a hollow body structure are preferable. For example, when the base polymer is an acrylic polymer, the organic substance other than the type of the base polymer is an organic substance other than the acrylic polymer, and when the base polymer is a polyester resin, the organic substance other than the type of the base polymer is an organic substance other than the polyester resin.

The filler may be a filler having a composition different from that of the outside (core-shell filler), or may be a filler having a composition identical to that of the inside (filler having no boundary between the inside and the outside).

Examples of the filler whose surface is made of an organic substance other than the base polymer type include a filler whose surface is made of an olefin-based resin and a filler whose surface is made of a polysiloxane-based resin. Examples of the filler having an olefin resin surface include olefin fillers having an olefin resin as a whole and fillers having an olefin resin surface and a different material inside. As the filler having a surface made of a silicone resin, there may be mentioned a silicone filler having a surface made of a silicone resin as a whole and a filler having a surface made of a silicone resin and having an interior made of a different material. The filler has a small interaction with the acrylic component in the acrylic pressure-sensitive adhesive layer and the monomer component in the polyester pressure-sensitive adhesive layer, is less likely to break when the pressure-sensitive adhesive layer is stretched, and has more excellent reworkability.

The shape of the filler may be: spherical, lamellar (scaly), dendritic, fibrous, irregularly shaped (polyhedral), and the like. Among them, spherical shape is preferable from the viewpoint of excellent uniform dispersibility.

The average particle diameter of the filler as a whole is, for example, 0.5 μm or more, preferably 0.8 μm or more (for example, 3 μm or more, and typically 5 μm or more). When the average particle diameter is not less than the above value, it is preferable in terms of maintaining the viscosity and dispersibility of the adhesive composition satisfactorily. The upper limit of the average particle diameter is, for example, 50 μm or less, preferably 30 μm or less, more preferably 25 μm or less, and still more preferably 15 μm or less. When the average particle diameter becomes smaller, the adhesive property tends to be suppressed from decreasing. From the viewpoint of the appearance of the adhesive layer, the average particle diameter is preferably small. In the present specification, the average particle diameter of the filler means a particle diameter (50% median particle diameter) at which the cumulative particle size on a weight basis in the particle size distribution obtained by measurement by a sieving method is 50%.

The volume ratio of the filler to the total mass of the adhesive layer is preferably 0.01X10 ^-2 cm ³ /g～30×10 ^-2 cm ³ Preferably 0.1X10 g ^-2 cm ³ /g～25×10 ^-2 cm ³ Preferably 0.5X10 g ^-2 cm ³ /g～20×10 ^-2 cm ³ Preferably 0.7X10 g ^-2 cm ³ /g～10×10 ^-2 cm ³ Per g, particularly preferably 1X 10 ^-2 cm ³ /g～7×10 ^-2 cm ³ And/g. When the above volume ratio is within the above range, both impact resistance and reworkability are more excellent. The above-mentioned filler volume ratio is represented by [ the volume (cm) of filler in the adhesive layer ³ ) Total mass of adhesive layer (g)]And (5) calculating.

The content of the filler in the adhesive layer is preferably more than 0 part by mass and 40 parts by mass or less, more preferably 0.008 parts by mass to 30 parts by mass, still more preferably 0.1 parts by mass to 20 parts by mass, still more preferably 0.2 parts by mass to 10 parts by mass, and particularly preferably 0.4 parts by mass to 6 parts by mass, relative to 100 parts by mass of the total amount of the base polymer. When the content is 40 parts by mass or less, both impact resistance and reworkability are more excellent.

The proportion of the filler in the pressure-sensitive adhesive layer is preferably 0.05 to 30% by mass, more preferably 0.1 to 20% by mass, still more preferably 0.5 to 10% by mass, and particularly preferably 1 to 5% by mass, relative to 100% by mass of the total amount of the pressure-sensitive adhesive layer. When the ratio is within the above range, the hardness of the adhesive layer can be made moderate. In addition, reworkability is excellent.

The pressure-sensitive adhesive layer may contain additives such as a crosslinking agent, a crosslinking accelerator, an antioxidant, a plasticizer, a softener, a surfactant, an antistatic agent, a surface lubricant, a leveling agent, a light stabilizer, an ultraviolet absorber, a polymerization inhibitor, a foil, an anticorrosive agent, and a colorant (dye, pigment, etc.), as necessary, within a range that does not impair the effects of the present invention. The above additives may be used singly or in combination of two or more.

The rust inhibitor is a compound for preventing rust (rusting) and corrosion of metals. When the adherend is a metal, rust and corrosion can be suppressed when the double-sided pressure-sensitive adhesive sheet is bonded. Examples of the rust inhibitor include: amine compounds, benzotriazole compounds, nitrite salts, and the like. Furthermore, there may be mentioned: ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, cyclohexylammonium N-cyclohexylcarbamate (CHC), and the like. The rust inhibitor may be used alone or in combination of two or more.

The content of the rust inhibitor is not particularly limited, but is preferably 0.02 to 15 parts by mass based on 100 parts by mass of the base polymer. When the content is 0.02 parts by mass or more, good corrosion resistance is easily obtained. When the content is 15 parts by mass or less, transparency is easily ensured.

Among them, benzotriazole compounds are preferable as the rust inhibitor, in terms of the ability to obtain the compatibility with the base polymer, the adhesion reliability, the transparency and the corrosion resistance at a high level in a balanced manner, and in terms of the ability to obtain excellent appearance.

The content of the benzotriazole compound is not particularly limited, but is preferably 0.02 to 3 parts by mass, more preferably 0.02 to 2.5 parts by mass, and still more preferably 0.02 to 2 parts by mass, based on 100 parts by mass of the base polymer.

The thickness of the pressure-sensitive adhesive layer (total thickness of the pressure-sensitive adhesive layer on one side) is 12 μm or more, preferably 20 μm or more, more preferably 40 μm or more, still more preferably 50 μm or more, and particularly preferably 60 μm or more. The above thickness of 12 μm or more gives an adhesive sheet excellent in impact resistance. The thickness of the pressure-sensitive adhesive layer is, for example, 200 μm or less, preferably 100 μm or less. When the thickness is 200 μm or less, the thickness of the double-sided adhesive sheet can be made thinner. The thickness of the adhesive layers on the two sides may be the same or different.

The total thickness of the adhesive layers (the total of the adhesive layers on both sides of the substrate) in the double-sided adhesive sheet of the present invention is not particularly limited, and is preferably 25 μm or more, more preferably 40 μm or more, and still more preferably 100 μm or more. When the thickness is 25 μm or more, the impact resistance of the double-sided adhesive sheet is more excellent. The total thickness of the adhesive layer on one side is, for example, 300 μm or less, preferably 200 μm or less. When the thickness is 300 μm or less, the thickness of the double-sided adhesive sheet can be made thinner.

The Z-axis adhesive strength of the adhesive layer at 23℃is preferably 0.6MPa or more, more preferably 0.7MPa or more. When the Z-axis adhesive force is 0.6MPa or more, the double-sided adhesive sheet is less likely to peel from the adherend when impacted. In the case where the double-sided adhesive sheet has a plurality of adhesive layers on one side of the substrate, the Z-axis adhesive strength of at least one of the adhesive layers is preferably within the above range at 23 ℃, and more preferably the Z-axis adhesive strength of all the adhesive layers is within the above range at 23 ℃.

The pressure-sensitive adhesive layer may be in any form, and may be, for example, emulsion type, solvent type (solution type), active energy ray-curable type, hot melt type (hot melt type), or the like. Among them, a solvent-based or active energy ray-curable adhesive composition is preferable in that an adhesive layer excellent in productivity can be easily obtained.

Examples of the active energy ray include ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron rays, ultraviolet rays, and the like, and ultraviolet rays are particularly preferred. That is, the active energy ray-curable adhesive layer is preferably an ultraviolet ray-curable adhesive layer.

The adhesive layer may be produced, for example, as follows: coating (coating) an adhesive composition for forming an adhesive layer on a release liner, and drying and curing the resulting adhesive composition layer; the adhesive composition is coated (coated) on a release liner, and the resulting adhesive composition layer is cured by irradiation with active energy rays. If necessary, the material may be further dried by heating.

(Release liner)

The double-sided adhesive sheet may be attached with a release liner on the surface (adhesive surface) of the adhesive layer before use. Each of the two surfaces of the double-sided pressure-sensitive adhesive sheet may be protected by two release liners, or may be protected by one release liner having two surfaces as release surfaces in a roll-like form (roll). The release liner is used as a protective material for the adhesive layer and is peeled off when attached to an adherend. The release liner may not be necessarily provided.

The release liner may be a conventional release paper, and examples thereof include, but are not particularly limited to, a substrate having a release treatment layer, a low-tackiness substrate containing a fluoropolymer, a low-tackiness substrate containing a nonpolar polymer, and the like. Examples of the substrate having the release-treated layer include plastic films and papers obtained by surface treatment with a release-treating agent such as polysiloxanes, long-chain alkyl groups, fluorine-containing agents, and molybdenum sulfide. The fluoropolymer in the low-tackiness base material containing a fluoropolymer may be exemplified by: polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylfluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, and the like. Examples of the nonpolar polymer include an olefin resin (e.g., polyethylene, polypropylene, etc.). The release liner may be formed by a known or conventional method. In addition, the thickness of the release liner is not particularly limited.

The double-sided adhesive sheet is preferably used for attaching an electric and electronic component to a component of an electric and electronic device. The double-sided adhesive sheet is preferably used for the purpose of attaching components of the electric and electronic devices to the two adhesive surfaces, that is, for the purpose of fixing members of the electric and electronic devices to each other. The double-sided adhesive sheet may be used for any of the purposes of fixing the members to each other and the purposes of temporary fixation. For example, when the double-sided adhesive sheet is used for fixing and temporarily fixing components of an electrical and electronic apparatus, there are cases where the double-sided adhesive sheet must be peeled off and reworked due to occurrence of a defect in the adhesion work of the double-sided adhesive sheet, or where the double-sided adhesive sheet must be peeled off for repair, replacement, inspection, reuse, or the like of a member having an adherend to which the double-sided adhesive sheet is adhered. In this way, when the double-sided adhesive sheet is used for fixing and temporarily fixing components of, for example, electrical and electronic equipment, the frequency of removing the double-sided adhesive sheet is high.

Among them, the double-sided adhesive sheet is preferably used by bonding outer frames of optical members (particularly, electric and electronic devices) to each other. Therefore, the double-sided pressure-sensitive adhesive sheet can be preferably used even if the width is 5mm or less, preferably 3mm or less.

The term "electric and electronic equipment" refers to equipment corresponding to at least one of electric equipment and electronic equipment. Examples of the electric and electronic devices include: image display devices such as liquid crystal displays, electroluminescent displays, and plasma displays, portable electronic devices, and the like.

Examples of the portable electronic device include: a mobile phone, a smart phone, a tablet personal computer, a notebook personal computer, various wearable devices (for example, wrist wearing type worn on a wrist such as a wristwatch, modularized type worn on a part of a body with a clip, a band, or the like, eye wearing (eye wearing) type including glasses type (monocular type, binocular type, helmet type is also included), clothing type worn on a shirt, socks, hat, or the like in the form of, for example, ornaments, ear wearing type worn on an ear such as an earphone, or the like), a digital camera, a digital video camera, an acoustic device (portable music player, recording pen, or the like), a calculator (desktop calculator, or the like), a portable game device, an electronic dictionary, an electronic notepad, an electronic book, a vehicle-mounted information device, a portable radio, a portable television, a portable printer, a portable scanner, a portable modem, or the like. In this specification, "portable" means that portability is insufficient only in that it can be carried, and that it has a level that an individual (a standard adult) can relatively easily carry. The double-sided adhesive sheet is used, for example, such that an adhesive layer is in close contact with a member of the portable electronic device.

The double-sided adhesive sheet of the present invention is excellent in impact resistance and less prone to occurrence of sticking out. Therefore, for example, when used in a portable electronic device, breakage and peeling are less likely to occur even when a drop impact is applied or when an adherend is deformed, and the adhesive layer is less likely to protrude from the adhesive region even when repeatedly bent. In addition, the double-sided adhesive sheet of the present invention may have a structure excellent in bendability, and in this case, the adhesive layer is less likely to protrude from the adhesive region even when subjected to repeated bending.

Examples

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The amounts and physical properties of the components in the base material, the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive sheet produced in each of examples and comparative examples are shown in the table. The blending amount of each component in the table represents parts by mass.

Example 1

(preparation of adhesive layer)

68 parts by mass of toluene, 95 parts by mass of Butyl Acrylate (BA) and 5 parts by mass of Acrylic Acid (AA) were charged into a reactor having a thermometer, a stirrer, a nitrogen inlet pipe and a reflux cooler, and nitrogen substitution was performed for 1 hour or more. 0.2 parts by mass of Azobisisobutyronitrile (AIBN) as an initiator was added, and then the internal bath temperature was raised to 62℃and the same temperature was maintained, and the reaction was continued until the completion of the reaction, followed by cooling, to terminate the polymerization reaction. Relative to the polymer obtained: 100 parts by mass of an isocyanate compound (trade name "cornonate L", manufactured by eastern co., ltd.) was added: 5 parts by mass and an epoxy compound (trade name "tetra C", mitsubishi gas chemical Co., ltd.): 0.02 part by mass of a terpene phenol tackifying resin (trade name "YS Polyster T115", manufactured by Ann Chemicals Co., ltd.): 20 parts by mass of polyethylene powder (trade name "Flowsen UF-80", manufactured by Sumitomo Co., ltd.) as a filler: 2 parts by mass and benzotriazole: 0.8 part by mass, thereby preparing an adhesive composition.

The adhesive composition was applied to a release-treated layer of a polyethylene terephthalate film (product name "MRF#38", manufactured by Mitsubishi chemical corporation) having a thickness of 38 μm, which was obtained by release-treating one side with polysiloxane, and dried at 100℃for 3 minutes, thereby producing an adhesive layer.

(production of adhesive sheet)

A double-sided pressure-sensitive adhesive sheet with a substrate of example 1 was produced by bonding the pressure-sensitive adhesive layers obtained above to both surfaces of a polyethylene terephthalate (PET) film (trade name "Lumirror S10", manufactured by ori corporation) as a substrate. In the examples and comparative examples, the adhesive layer provided on one surface of the substrate is sometimes referred to as a "first adhesive layer", and the adhesive layer provided on the other surface is sometimes referred to as a "second adhesive layer".

Example 2

A double-sided adhesive sheet with a substrate of example 2 was produced in the same manner as in example 1, except that a urethane film (trade name "Esmer URS ET-B", polyether polyol, maximum value of loss tangent tan δ at a frequency of 10kHz to 3.5 MHz: 0.40, shore D hardness: 90, manufactured by japan macadam co., ltd.) was used as the substrate, and the thickness of the adhesive layer was changed as shown in table 1.

Example 3

A double-sided adhesive sheet with a substrate of example 3 was produced in the same manner as in example 1, except that a polypropylene film (trade name "Trefan", manufactured by eastern co.) was used as the substrate.

Example 4

A double-sided adhesive sheet with a substrate of example 4 was produced in the same manner as in example 2, except that the thickness of the substrate and the thicknesses of the adhesive layers (the thicknesses of the first adhesive layer and the second adhesive layer) formed on both sides of the substrate were changed as shown in table 1.

Example 5

(preparation of adhesive layer)

68 parts by mass of toluene, 95 parts by mass of Butyl Acrylate (BA) and 5 parts by mass of Acrylic Acid (AA) were charged into a reactor having a thermometer, a stirrer, a nitrogen inlet pipe and a reflux cooler, and nitrogen substitution was performed for 1 hour or more. 0.2 part by mass of azobisisobutyronitrile as an initiator was added, and then the internal bath temperature was raised to 62℃and kept at the same temperature, and the reaction was continued until the reaction was substantially completed, followed by cooling, to complete the polymerization reaction. Relative to the polymer obtained: 100 parts by mass of an isocyanate compound (trade name "cornonate L", manufactured by eastern co., ltd.) was added: 5 parts by mass and an epoxy compound (trade name "tetra C", mitsubishi gas chemical Co., ltd.): 0.02 part by mass of a terpene phenol tackifying resin (trade name "YS Polyster T115", manufactured by Ann Chemicals Co., ltd.): 20 parts by mass of benzotriazole: 0.8 part by mass, thereby preparing an adhesive composition.

(production of adhesive sheet)

A double-sided pressure-sensitive adhesive sheet with a substrate of example 5 was produced by bonding the pressure-sensitive adhesive layers obtained above to both surfaces of a substrate, using a urethane film (trade name "DUS604", manufactured by dow co.) as the substrate.

Example 6

(preparation of adhesive layer)

68 parts by mass of toluene, 95 parts by mass of Butyl Acrylate (BA) and 3 parts by mass of Acrylic Acid (AA) were charged into a reactor having a thermometer, a stirrer, a nitrogen inlet pipe and a reflux cooler, and nitrogen substitution was performed for 1 hour or more. 0.2 part by mass of azobisisobutyronitrile as an initiator was added, and then the internal bath temperature was raised to 62℃and kept at the same temperature, and the reaction was continued until the reaction was substantially completed, followed by cooling, to complete the polymerization reaction. Relative to the polymer obtained: 100 parts by mass of a hydrogenated styrene-based thermoplastic elastomer (SEBS) (trade name "Tuftec", manufactured by Asahi Kabushiki Kaisha): 2 parts by mass of an isocyanate compound (trade name "cornonate L", manufactured by Tosoh corporation): 5 parts by mass and an epoxy compound (trade name "tetra C", mitsubishi gas chemical Co., ltd.): 0.02 part by mass of a terpene phenol tackifying resin (trade name "YS Polyster T115", manufactured by Ann Chemicals Co., ltd.): 20 parts by mass of polyethylene powder (trade name "Flowsen UF-80", manufactured by Sumitomo Co., ltd.) as a filler: 2 parts by mass and benzotriazole: 0.8 part by mass, thereby preparing an adhesive composition.

(production of adhesive sheet)

The double-sided pressure-sensitive adhesive sheet with a substrate of example 6 was produced by bonding the pressure-sensitive adhesive layers obtained above to both surfaces of a substrate, using a urethane film (trade name "Esmer URS ET-B", manufactured by japan macadam corporation) as the substrate.

Examples 7 and 8

The same procedure as in example 2 was repeated except that the thicknesses of the adhesive layers (thicknesses of the first adhesive layer and the second adhesive layer) formed on both sides of the substrate were changed as shown in table 1, thereby producing double-sided adhesive sheets with substrates of examples 7 and 8.

Comparative example 1

(production of base Material)

To 63 parts by mass of ethyl acetate, a resin component relative to a polyester-based polymer solution (trade name "Nichigo Polyester NP-110S50EO", solid content concentration: 50% by mass, manufactured by Mitsubishi chemical corporation) was added in a reactor having a thermometer, a stirrer, a nitrogen inlet pipe, and a reflux cooler: 100 parts by mass of an isocyanate compound (trade name "cornate HX", manufactured by eastern co., ltd.): 3 parts by mass of a terpene phenol tackifying resin (trade name "YS Polyster T115", manufactured by Ann Chemicals Co., ltd.): 20 parts by mass, thereby preparing an adhesive composition.

The adhesive composition was applied to a release-treated layer of a polyethylene terephthalate film (product name "MRF#38", manufactured by Mitsubishi chemical corporation) having a thickness of 38 μm, which was obtained by release-treating one side with polysiloxane, and dried at 100℃for 3 minutes, thereby forming an adhesive layer X as a base material.

(production of adhesive sheet)

The adhesive layers produced in example 1 were bonded to both surfaces of the obtained adhesive layer X, respectively, to produce a double-sided adhesive sheet of comparative example 1.

Comparative example 2

A double-sided adhesive sheet with a substrate of comparative example 2 was produced in the same manner as in example 1, except that the thickness of the substrate and the thicknesses of the adhesive layers formed on both sides of the substrate (the thicknesses of the first adhesive layer and the second adhesive layer) were changed as shown in table 1.

Comparative example 3

A double-sided adhesive sheet with a substrate of comparative example 3 was produced in the same manner as in example 2, except that the thickness of the substrate and the thicknesses of the adhesive layers formed on both sides of the substrate (the thicknesses of the first adhesive layer and the second adhesive layer) were changed as shown in table 1.

Comparative example 4

A double-sided adhesive sheet with a substrate of comparative example 4 was produced in the same manner as in example 1, except that the thickness of the substrate and the thicknesses of the adhesive layers formed on both sides of the substrate (the thicknesses of the first adhesive layer and the second adhesive layer) were changed as shown in table 1.

< evaluation >

The double-sided adhesive sheets obtained in examples and comparative examples were evaluated as follows. The results are shown in the table.

(1) Storage modulus of the substrate

The substrates produced in examples and comparative examples were cut into a width of 5mm×30mm, the long side of 30mm was clamped at a chuck pitch of 15mm on a dynamic viscoelasticity measuring apparatus (trade name "Rheogel-E4000", manufactured by UBM corporation), the temperature rise rate was set to 5 ℃/min, the tensile viscoelasticity modulus was measured in a range of-60 ℃ to 100 ℃, and a calibration curve was synthesized at a reference temperature of 23 ℃, whereby the maximum value of the loss tangent tan δ at 23 ℃ and at a frequency of 10kHz to 3.5MHz was calculated.

(2) Compression test

Compression tests were performed as shown in fig. 2. Specifically, first, the release liner was peeled off from the double-sided adhesive sheets produced in examples and comparative examples, and a plurality of the double-sided adhesive sheets were laminated to a total thickness of 1mm or more, thereby producing a double-sided adhesive sheet laminate. Subsequently, the double-sided adhesive sheet laminate was cut into a square of 5mm×5mm, whereby an evaluation sample 7 was produced. The evaluation sample 7 was placed on a flat table 9, and a PET film 8 (product name "MRF25", manufactured by mitsubishi chemical corporation) having a thickness of 25 μm, which was obtained by subjecting one surface to a peeling treatment with polysiloxane, was attached to the upper surface of the evaluation sample 7. Then, a compression test was performed by applying a load P in the thickness direction of the sample 7 from the upper side of the PET film under a condition of a stress of 1.5MPa and a frequency of 0.5Hz using a micro servo (model "MMT-250NM-10", manufactured by Shimadzu Access corporation) and repeating the operation of releasing the load P1000 times. The thickness reduction rate was calculated by the following equation with the thickness of the evaluation sample 7 before the compression test as the initial thickness and the thickness of the evaluation sample 7 after the compression test as the thickness after the test.

(3) Z-axis adhesive force

The double-sided pressure-sensitive adhesive sheets produced in examples and comparative examples were punched out in a frame shape having an outer diameter of 24.5mm square and a width of 2mm in a state of being sandwiched between release liners. Then, the release liner was peeled off from the double-sided adhesive sheet, sandwiched and pressure-bonded between a stainless steel plate having a square hole with a thickness of 2mm and an outer shape of 50mm and a square stainless steel plate having a thickness of 3mm and an outer shape of 25mm, and allowed to stand at 50℃for 2 hours, and returned to normal temperature to give an evaluation sample. A column having a diameter of 10mm was mounted on an upper jig of a tensile tester by using a tensile tester "Autograph AG-IS" (manufactured by Shimadzu corporation), and a base was provided on the lower side, and a test piece was placed thereon with a square stainless steel plate (stainless steel plate without holes) as the lower side. Then, a square stainless steel plate (stainless steel plate without holes) was pressed into a cylinder having a diameter of 10mm at a speed of 50 mm/min, and the stress and strain amount at the time of peeling were converted into energy.

Z-axis adhesive force (MPa) =until peelingStress (N)/adhesive area (mm) from separation ² )

(4) Impact resistance

The double-sided pressure-sensitive adhesive sheets produced in examples and comparative examples were punched out in a frame shape having an outer diameter of 24.5mm square and a width of 2mm in a state of being sandwiched between release liners. Then, the release liner was peeled from the double-sided adhesive sheet, sandwiched and pressure-bonded between a stainless steel plate having a square hole with a thickness of 2mm and an outline of 50mm and a square stainless steel plate having a thickness of 3mm and an outline of 25mm, and allowed to stand in an environment at a temperature of 50℃for 2 hours, and then returned to room temperature to give an evaluation sample. A cylindrical measuring table having a length of 50mm, an outer diameter of 49mm and an inner diameter of 43mm was set on a base of a Du Bangshi impact tester (manufactured by Toyo Seisakusho Co., ltd.), and a test piece was placed thereon with a square stainless steel plate (stainless steel plate without holes) as a lower side. A stainless steel core with a tip radius of 3.1mm was placed on a test piece, the falling weight and falling height were changed, energy was increased until peeling was generated, the falling height was changed 50mm to 500mm each time under the condition that the falling weight was 100g, the falling height was changed 50mm to 500mm each time under the condition that the falling weight was 150g, the falling height was changed 50mm to 500mm each time under the condition that the falling weight was 200g, the falling height was changed 50mm to 500mm each time under the condition that the falling weight was 400mm, and the falling height was changed 50mm to 500mm each time under the condition that the falling weight was 300 g. At this time, no test was performed on the evaluated energy, and the load and the height were set so that the energy was not repeated. Then, the energy of at least any one of the stainless steel plates until peeling was calculated as load×height, and as a result, the obtained value was shown as an impact absorption amount in the table.

(5) Glue paste protrusion

After the compression test (2), the case where the protrusion of the adhesive was not visually confirmed at the end of the evaluation sample was evaluated as "good (∈)", and the case where the protrusion of the adhesive was confirmed was evaluated as "poor (×)".

As shown in Table 1, the double-sided pressure-sensitive adhesive sheets of examples were excellent in impact absorption, impact resistance, and adhesive sticking out was not confirmed, and were evaluated as good, since the thickness was 60 μm to 400 μm and the reduction rate of the thickness was 30% or less. On the other hand, when the thickness reduction ratio of the double-sided adhesive sheet was more than 30% (comparative examples 1 and 2), the sticking out was confirmed, and the evaluation was poor. In addition, when the thickness of the adhesive layer was small (comparative examples 3 and 4), it was evaluated that the impact resistance was poor.

The following describes modifications of the disclosed invention.

[ appendix 1] A double-sided adhesive sheet having a substrate and an adhesive layer provided on at least one face of the substrate, wherein,

the thickness of the adhesive layer is 12 μm or more,

the thickness of the double-sided adhesive sheet is 60 μm or more,

Compression test:

The double-sided adhesive sheet according to appendix 2, wherein the storage modulus of the substrate is 2MPa or more and the ratio of the thickness of the substrate to the thickness of the double-sided adhesive sheet is 10% or more.

The double-sided adhesive sheet according to any one of supplementary notes 3 to 1 or 2, wherein the thickness of the base material is 20 μm or more.

[ additional note 4] the double-sided adhesive sheet according to any one of additional notes 1 to 3, wherein the Z-axis adhesive strength of the adhesive layer is 0.6MPa or more at 23 ℃.

The double-sided adhesive sheet according to any one of supplementary notes 5 to 1 to 4, wherein the adhesive constituting the adhesive layer comprises at least an acrylic adhesive, a polyester adhesive, a rubber adhesive or a urethane adhesive.

The double-sided adhesive sheet according to any one of supplementary notes 6 to 1 to 5, wherein the double-sided adhesive sheet is a double-sided adhesive sheet for fixing members in an electric and electronic apparatus to each other.

Supplementary note 7 an electric and electronic apparatus having the double-sided adhesive sheet described in supplementary note 6, the double-sided adhesive sheet fixing members to each other by two adhesive faces.

Claims

1. A double-sided adhesive sheet having a substrate and an adhesive layer provided on at least one face of the substrate, wherein,

the thickness of the adhesive layer is 12 μm or more,

the thickness of the double-sided adhesive sheet is 60 μm or more,

compression test:

2. The double-sided adhesive sheet according to claim 1, wherein the storage modulus of the substrate is 2MPa or more,

the ratio of the thickness of the base material to the thickness of the double-sided adhesive sheet is 10% or more.

3. The double-sided adhesive sheet according to claim 1 or 2, wherein the thickness of the substrate is 20 μm or more.

4. The double-sided adhesive sheet according to claim 1 or 2, wherein the adhesive layer has a Z-axis adhesive force of 0.6MPa or more at 23 ℃.

5. The double-sided adhesive sheet according to claim 1 or 2, wherein the adhesive constituting the adhesive layer comprises at least an acrylic adhesive, a polyester adhesive, a rubber adhesive or a urethane adhesive.

6. The double-sided adhesive sheet according to claim 1 or 2, wherein the double-sided adhesive sheet is a double-sided adhesive sheet for fixation of members in an electric and electronic apparatus to each other.

7. An electrical and electronic apparatus having the double-sided adhesive sheet according to claim 6,

the double-sided adhesive sheet fixes the members to each other by two adhesive faces.