Adhesive sheet for flexible display, laminate, and method for manufacturing flexible display

Abstract

The object of the present invention is to provide an adhesive sheet, a laminate, and a method for manufacturing a flexible display, which can form a flexible display having not only excellent bending properties but also excellent winding offset resistance and dustproof properties. The above object is solved by an adhesive sheet for a flexible display, which includes an acrylic adhesive layer on a release agent layer of an antistatic treatment release film, the surface resistance value of the release agent layer in an atmosphere of 23°C - 50% RH is 1×10<supgt;11< / supgt; Ω / square or less, the main component of the release agent layer is linear silicone, and the content of branched silicone is 1% by mass or less, and the glass transition temperature of the acrylic adhesive layer is -55°C or less.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet for forming a flexible display, a laminate having an adhesive layer formed of the adhesive sheet, and a flexible display. Background Art

[0002] In recent years, input devices that combine an image display device such as a liquid crystal display (LCD) or an organic electroluminescence (organic EL (electroluminescence)) display (organic light-emitting diode (OLED)) with a touch panel have become popular. A transparent conductive film used in a touch panel is laminated via an adhesive layer on a member such as a support glass. In addition, a polarizing plate film used in an image display device is attached via an adhesive layer to a liquid crystal module or an organic EL module.

[0003] As the image display device, flat panel displays using a glass substrate are mainstream, but in recent years, flexible displays such as foldable displays or rollable displays using a flexible substrate such as plastic have been developed. Compared with conventional flat panel displays using a glass substrate, such flexible displays have various advantages such as light weight, thinness, flexibility, and excellent design.

[0004] For the adhesive sheet, properties that do not cause foaming and peeling in a high-temperature environment or a high-temperature and high-humidity environment have been required. In recent years, flexibility has been further required. By way of example of market products, the property of having flexibility so as to be usable for a foldable display is gradually becoming a basic performance. However, although attempts have been made to improve the flexibility at a specific location, no improvement has been made to an adhesive sheet that simultaneously satisfies the flexibility at multiple locations. As the flexibility, a property that does not cause foaming, floating, and peeling during repeated bending is required.

[0005] To solve these problems, Patent Document 1 discloses an adhesive containing a base polymer, a photo-curable compound, and a photoinitiator. In addition, Patent Document 2 discloses a carrier sheet for a flexible device including a substrate having antistatic properties, an adhesive layer, and a release sheet.

[0006] [Prior Art Documents]

[0007] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2020-097737

[0009] [Patent Document 2] Japanese Patent Laid-Open Publication No. 2018-203873 Summary of the Invention

[0010] [Problems to be Solved by the Invention]

[0011] Furthermore, in recent years, as a more advanced display, a rollable display has attracted much attention. As an adhesive sheet used in a rollable display, more stringent bendability is required than before. In addition to the bendability at a specific location (foldable bendability), in order to cope with movements such as twisting, strain adaptability with bendability at multiple locations (rollable bendability) is also required. In addition, in a rollable display, in order to make the clarity of the displayed image directly visible, the market requirement level for dustproofness that does not allow dust or dirt to mix in is at a higher level than before. In addition, when curing in a state of being wound by roll-to-roll in the case of mass-producing an adhesive sheet, there is a concern that the clarity of the image quality will be impaired due to the positional deviation (winding deviation) of the adhesive layer in the shear direction.

[0012] Therefore, an object of the present invention is to provide an adhesive sheet that can form a flexible display having not only excellent bendability but also excellent winding deviation resistance and dustproofness.

[0013] In addition, an object of the present invention is to provide an adhesive sheet having excellent strain adaptability, which can also be applied to uses that require more stringent bendability such as a rollable display.

[0014] [Technical Means for Solving the Problem]

[0015] The inventors of the present invention have repeatedly made intensive studies, and as a result, found that the problems of the present invention can be solved in the following forms, and thus completed the present invention.

[0016] That is, the present invention relates to an adhesive sheet for a flexible display, which includes an acrylic adhesive layer on a release agent layer of an antistatic release film, the surface resistance value of the release agent layer in an atmosphere of 23°C - 50% RH is 1×10 11 Ω / sq or less, the main component of the release agent layer is linear silicone, and the content rate of branched silicone is 1% by mass or less, and the glass transition temperature of the acrylic adhesive layer is -55°C or less.

[0017] In addition, the present invention relates to the above-mentioned adhesive sheet for a flexible display, wherein the film thickness of the acrylic adhesive layer is 50 μm or more.

[0018] In addition, the present invention relates to the above-mentioned adhesive sheet for a flexible display, wherein the acrylic adhesive layer contains an acrylic copolymer (A), and the acrylic copolymer (A) contains an acrylic copolymer having a mass average molecular weight of 800,000 or more.

[0019] In addition, the present invention relates to an adhesive sheet for a flexible display, wherein the acrylic copolymer (A) is a copolymer of a monomer mixture containing at least one of (meth)acrylic acid alkyl ester monomers (a-1) having an alkyl group with 1 or 2 carbon atoms and (meth)acrylic acid alkyl ester monomers (a-2) having an alicyclic structure.

[0020] In addition, the present invention relates to an adhesive sheet for a flexible display, wherein the monomer mixture further contains a (meth)acrylic acid alkyl ester monomer (a-3) having an alkyl group with 8 to 12 carbon atoms, and the content of the monomer (a-3) is 80% by mass or more in 100% by mass of the monomer mixture.

[0021] In addition, the present invention relates to an adhesive sheet for a flexible display, wherein the acrylic adhesive layer contains an antistatic agent, and the surface resistance value of the acrylic adhesive layer in an atmosphere of 23°C - 50% RH is 1×10 10 Ω / sq or less.

[0022] In addition, the present invention relates to a method for manufacturing a laminate including an adherend and an acrylic adhesive layer, the method for manufacturing the laminate including: peeling the antistatic treatment release film from the adhesive sheet for a flexible display, and attaching the acrylic adhesive layer to the adherend.

[0023] In addition, the present invention relates to a method for manufacturing a flexible display including a flexible image display unit and an acrylic adhesive layer, the method for manufacturing the flexible display including: peeling the antistatic treatment release film from the adhesive sheet for a flexible display, and attaching the acrylic adhesive layer to the flexible image display unit.

[0024] [Effects of the Invention]

[0025] Through the present invention described above, it is possible to provide an adhesive sheet that can form a flexible display having not only excellent bendability but also excellent winding offset resistance and dust resistance compared to the prior art.

[0026] In addition, it can also be applied to applications that require more stringent bendability such as a rollable display, and by using the adhesive sheet of the present invention, it is possible to provide a flexible display that is small in storage, has a large screen during use, and has excellent visibility. [Brief Description of the Drawings]

[0027] Figure 1 is a schematic cross-sectional view partially showing an example of the adhesive sheet of the present invention.

[0028] Figure 2It is a schematic cross-sectional view showing in part a laminate as an example of the use of the pressure-sensitive adhesive sheet of the present invention.

[0029] Figure 3 It is a schematic cross-sectional view showing in part a display as an example of the use of the pressure-sensitive adhesive sheet of the present invention.

[0030] [Description of symbols]

[0031] 1: Adhesive layer 1

[0032] 2: Antistatic treatment release film

[0033] 3: Film base material (cover panel)

[0034] 4: Polarizing plate

[0035] 5: Adhesive layer 2

[0036] 6: Barrier layer

[0037] 7: Organic EL layer

[0038] 8: Support

[0039] 9: Organic EL unit Detailed implementation manners

[0040] Hereinafter, structural examples of the pressure-sensitive adhesive sheet, laminate, and display of the present invention will be described, but are not limited thereto.

[0041] Define the terms used in this specification. The so-called (meth)acrylate includes acrylate and methacrylate. The so-called monomer is a monomer containing an ethylenically unsaturated group. The so-called adherend refers to the object to which the pressure-sensitive adhesive sheet is to be attached. In the present invention, sheet, film, and tape are synonyms, and "RH" refers to relative humidity.

[0042] In addition, in this specification, the "acrylic copolymer (A)" is sometimes referred to as "copolymer (A)", the "adhesive for flexible display" is referred to as "adhesive", the "(meth)acrylate alkyl ester monomer (a1) having an alkyl group with 1 or 2 carbon atoms" is referred to as "monomer (a1)", the "(meth)acrylate alkyl ester monomer (a2) having an alicyclic structure" is referred to as "monomer (a2)", the "(meth)acrylate alkyl ester monomer (a3) having an alkyl group with 8 to 12 carbon atoms" is referred to as "monomer (a3)", the "monomer having a hydroxyl group or a carboxyl group (a4)" is referred to as "monomer (a4)", and the "other monomer (a5) capable of copolymerizing with monomers (a-1) to (a-4)" is referred to as "monomer (a5)".

[0043] In addition, unless otherwise noted, each of the various components appearing in this specification may be used alone independently or in combination of two or more.

[0044] "Adhesive sheet"

[0045] The adhesive sheet of the present invention includes an acrylic adhesive layer on a release agent layer of an antistatic-treated release film and is used for forming a flexible display.

[0046] The antistatic-treated release film is a film that includes an antistatic layer on one or both sides of a film substrate, and further includes a release agent layer on its upper surface with respect to the antistatic layer, and a release agent layer on the film substrate with respect to the surface that does not include the antistatic layer.

[0047] It can be formed by coating an adhesive on the release agent layer of the antistatic-treated release film by a known method.

[0048] <Acrylic adhesive layer>

[0049] Regarding the glass transition temperature (Tg) of the acrylic adhesive layer, the value obtained as a result of differential scanning calorimetry (DSC) of the adhesive layer is -55°C or lower. Preferably, it is -57°C or lower, and more preferably, it is -60°C or lower. By having the glass transition temperature of the acrylic adhesive layer be -55°C or lower, sufficient strain adaptability can be exhibited.

[0050] The acrylic adhesive layer is a sheet obtained by forming a thin film of an acrylic adhesive containing an acrylic copolymer (A) and optionally containing a hardener, additives, etc. on a release film by a known method.

[0051] The acrylic adhesive layer preferably contains an acrylic copolymer having a mass average molecular weight of 800,000 or more as the acrylic copolymer (A). In addition, it preferably contains an antistatic agent.

[0052] (Acrylic copolymer (A))

[0053] The acrylic copolymer (A) is a copolymer of a monomer mixture.

[0054] As the monomers constituting the acrylic copolymer (A), they can be classified into the following monomers (a-1) to monomers (a-5).

[0055] (a-1) An alkyl (meth)acrylate monomer having an alkyl group with 1 or 2 carbon atoms

[0056] (a-2) An alkyl (meth)acrylate monomer having an alicyclic structure

[0057] (a-3) An alkyl (meth)acrylate monomer having an alkyl group with 8 to 12 carbon atoms

[0058] (a-4) A monomer having a hydroxyl group or a monomer having a carboxyl group

[0059] (a-5) Other monomers capable of copolymerizing with monomers (a-1) to (a-4)

[0060] The acrylic copolymer (A) is a copolymer of a monomer mixture containing at least one of monomers (a-1) and (a-2), and thus has substituents that generate cohesion in the side chain. Thereby, an adhesive sheet excellent in flexibility and adhesiveness can be produced, and thus it is preferred.

[0061] In 100% by mass of the monomer mixture, the content of monomers (a-1) and (a-2) is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass. When both monomers (a-1) and (a-2) are contained, in 100% by mass of the monomer mixture, the total amount of the two is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass.

[0062] By having a content of 1% by mass or more, sufficient cohesion can be easily obtained. In addition, by having a content of 30% by mass or less, it is easy to balance cohesion and moderateness, and thus it is preferred.

[0063] [Monomer (a-1)]

[0064] Monomer (a-1) is an alkyl (meth)acrylate monomer having an alkyl group with 1 or 2 carbon atoms. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, etc. can be cited. Among them, from the viewpoints of flexibility and adhesiveness, methyl (meth)acrylate is preferred.

[0065] [Monomer (a-2)]

[0066] Monomer (a-2) is an alkyl (meth)acrylate monomer having an alicyclic structure. Specifically, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. can be cited. Among them, from the viewpoints of flexibility and adhesiveness, isobornyl (meth)acrylate is preferred.

[0067] [Monomer (a-3)]

[0068] The monomer (a-3) is an alkyl (meth)acrylate monomer having an alkyl group with 8 to 12 carbon atoms. Specifically, examples include: octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, etc. Among them, from the viewpoint of flexibility, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate are preferred.

[0069] If the alkyl (meth)acrylate monomer (a-3) having an alkyl group with 8 to 12 carbon atoms is further used, the softening property of the adhesive is improved, a tough adhesive layer can be obtained, and the flexibility can be improved, so it is more preferred.

[0070] In 100% by mass of the monomer mixture, the content of the monomer (a-3) is preferably 50% to 98% by mass, more preferably 65% to 98% by mass, and still more preferably 80% to 95% by mass.

[0071] When the content is 50% by mass or more, sufficient softening property can be easily obtained. In addition, when the content is 98% by mass or less, it is easy to ensure the contents of the monomer (a-1) or monomer (a-2) that generates cohesion and the monomer (a-4) that forms crosslinking points, and it is easy to balance softening property and cohesion, so it is preferred.

[0072] [Monomer (a-4)]

[0073] The monomer (a-4) is a monomer having a hydroxyl group or a monomer having a carboxyl group.

[0074] The monomer having a hydroxyl group is not limited as long as it has a hydroxyl group in the molecule. Specifically, examples include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, from the viewpoints of cohesion and adhesiveness, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0075] The monomer containing a carboxyl group is not limited as long as it has a carboxyl group in the molecule. Specifically, examples include: (meth)acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, monoethyl maleic acid, itaconic acid, citraconic acid, fumaric acid, etc. Among them, from the viewpoints of cohesion and adhesiveness, (meth)acrylic acid is preferred.

[0076] In addition, by containing the monomer (a-4), the cohesion of the adhesive is improved, a tough adhesive layer can be obtained, and the adhesiveness can be improved, so it is more preferred.

[0077] Regarding the content rate of monomer (a-4), it is preferably 0.5% by mass to 2.5% by mass, more preferably 0.5% by mass to 2.0% by mass in 100% by mass of the monomer mixture. In the case of containing both a monomer having a hydroxyl group and a monomer having a carboxyl group, regarding the total amount of the two, it is preferably 0.5% by mass to 2.5% by mass, more preferably 0.5% by mass to 2.0% by mass in 100% by mass of the monomer mixture.

[0078] When the content rate is 0.5% by mass or more, sufficient cohesion is easily obtained. When the content rate is 2.5% by mass or less, it is easy to balance cohesion and moderateness, so it is preferred.

[0079] From the viewpoint of easily balancing cohesion and moderateness, the case of containing both a monomer having a hydroxyl group and a monomer having a carboxyl group is preferred over the case of containing each alone.

[0080] [Monomer (a-5)]

[0081] Monomer (a-5) is another monomer capable of copolymerizing with monomers (a-1) to (a-4). The acrylic pressure-sensitive adhesive (A) of the present invention may further contain monomer (a-5) in addition to monomers (a-1) to (a-4).

[0082] Examples of monomer (a-5) include: (meth)acrylic acid alkyl ester monomers other than monomers (a-1) to (a-3), (meth)acrylic acid monomers having an epoxy group, (meth)acrylic acid monomers having an amino group, monomers having an alkyleneoxy group, other vinyl monomers, etc.

[0083] Examples of (meth)acrylic acid alkyl ester monomers other than monomers (a-1) to (a-3) include: propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, etc.

[0084] Examples of monomers having an epoxy group include: glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate, etc.

[0085] Examples of monomers having an amino group include: monoalkylamino esters of (meth)acrylic acid such as 2-(methylamino)ethyl (meth)acrylate, 2-(ethylamino)ethyl (meth)acrylate, 3-(methylamino)propyl (meth)acrylate, 3-(ethylamino)propyl (meth)acrylate, etc.

[0086] Examples of monomers having an alkyleneoxy group include monomers represented by the following general formula (1) or monomers represented by general formula (2).

[0087] [Chemical 1]

[0088]

[0089] [Chemical 2]

[0090]

[0091] In General Formulas (1) and (2), R1 and R2 are each independently a hydrogen atom or a methyl group, n and m are integers representing repeating units, and 1 ≤ n ≤ 25, 1 ≤ m ≤ 25, preferably 1 ≤ n ≤ 13, 1 ≤ m ≤ 5.

[0092] Examples of commercially available products of the monomer represented by General Formula (1) include: methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 1), methoxydiethylene glycol acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 2), methoxy triethylene glycol acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 3), methoxypolyethylene glycol #400 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 9), methoxypolyethylene glycol #600 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 13), methoxypolyethylene glycol #1000 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 23), methoxydiethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a methyl group, n = 2), methoxy triethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a methyl group, n = 3), methoxy tetraethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a methyl group, n = 4), methoxypolyethylene glycol #400 methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 9), methoxypolyethylene glycol #600 methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 13), methoxypolyethylene glycol #1000 methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (1), R1 is a hydrogen atom, n = 23).

[0093] Examples of commercially available products of the monomer represented by General Formula (2) include methoxy tripropylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in the said formula (2), R2 is a hydrogen atom, m = 3).

[0094] Examples of vinyl monomers include vinyl acetate, vinyl butenoate, styrene, acrylonitrile, and the like.

[0095] Regarding the content rate of monomer (a-5), it is preferably 5% by mass to 50% by mass in 100% by mass of the monomer mixture. If the content is 5% by mass or more, the cohesion is improved. In addition, if the content is 50% by mass or less, it is easy to balance cohesion and flexibility, so it is preferred.

[0096] [Production of acrylic copolymer (A)]

[0097] Acrylic copolymer (A) can be produced by polymerizing a monomer mixture. The polymerization can be known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc., and solution polymerization is preferred. Solvents used in solution polymerization are preferably acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone, etc. The polymerization temperature is preferably a boiling reaction at 60°C to 120°C. The polymerization time is preferably about 5 hours to 12 hours.

[0098] The polymerization initiator used in the polymerization is preferably a radical polymerization initiator. Radical polymerization initiators are generally peroxides and azo compounds. Examples of peroxides include dialkyl peroxides such as di-tert-butyl peroxide, diisopropylbenzene peroxide, tert-butyl isopropylbenzene peroxide, α,α'-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-bis(tert-butylperoxy)hexyne-3; peroxy esters such as tert-butyl peroxybenzoate, tert-butyl peroxyacetate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane; ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide; peroxyketals such as 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate; hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide; diacyl peroxides such as benzoyl peroxide, decanoyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide; and peroxydicarbonates such as bis(tert-butylcyclohexyl) peroxydicarbonate.

[0099] Examples of azo compounds include: 2,2'-azobisisobutyronitrile (abbreviation: AIBN (2,2'-azobisisobutyronitrile)), 2,2'-azobis(2-methylbutyronitrile) and other 2,2'-azobisbutyronitriles; 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile) and other 2,2'-azobisvaleronitriles; 2,2'-azobis(2-hydroxymethylpropionitrile) and other 2,2'-azobispropionitriles; 1,1'-azobis(cyclohexane-1-carbonitrile) and other 1,1'-azobis-1-alkanenitriles, etc.

[0100] Relative to 100 parts by mass of the monomer mixture, it is preferable to use 0.01 to 10 parts by mass of a polymerization initiator, and more preferably to use 0.05 to 2 parts by mass of a polymerization initiator.

[0101] [Mass average molecular weight (Mw)]

[0102] The mass average molecular weight of the copolymer (A) is preferably from 600,000 to 2,000,000, more preferably from 800,000 to 1,800,000, and still more preferably from 1,000,000 to 1,500,000. If it is in the range of 600,000 to 2,000,000, the cohesion is further improved, and the bending properties such as winding offset resistance and strain adaptability, and the adhesive strength are further improved. In addition, the mass average molecular weight is a value converted to polystyrene by gel permeation chromatography (GPC) method.

[0103] (Hardener)

[0104] The hardener improves the cohesion of the adhesive layer by reacting with the hydroxyl group and / or carboxyl group of the copolymer (A), and improves the bending property or the adhesive strength.

[0105] Examples of the hardener include: isocyanate compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, or metal chelates, etc. Among these, the bending property can be improved by using an isocyanate compound as the hardener, so it is preferred.

[0106] The isocyanate compound is an isocyanate having two or more isocyanate groups. Examples of the isocyanate compound are preferably isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and biuret bodies, allophanate bodies, and adducts thereof.

[0107] Aromatic polyisocyanates include, for example: 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4”-triphenylmethane triisocyanate, etc.

[0108] Aliphatic polyisocyanates include, for example: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (alias: HMDI (hexamethylene diisocyanate)), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

[0109] Aryl aliphatic polyisocyanates include, for example: ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylbenzene dimethyl diisocyanate, 1,3-tetramethylbenzene dimethyl diisocyanate, etc.

[0110] Cycloaliphatic polyisocyanates include, for example: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (alias: IPDI (isophorone diisocyanate), isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, etc.

[0111] The biuret body is a self-condensate of isocyanate monomers with a biuret bond formed by self-condensation. Examples of the biuret body include the biuret body of hexamethylene diisocyanate.

[0112] The urethane body is a trimer of isocyanate monomers. Examples include: the trimer of hexamethylene diisocyanate, the trimer of isophorone diisocyanate, the trimer of toluene diisocyanate, etc.

[0113] The adduct is a polyfunctional isocyanate compound formed by reacting an isocyanate monomer with a polyfunctional compound containing low-molecular-weight active hydrogen. Examples of the adduct include compounds formed by reacting trimethylolpropane with hexamethylene diisocyanate, compounds formed by reacting trimethylolpropane with toluene diisocyanate, compounds formed by reacting trimethylolpropane with xylylene diisocyanate, compounds formed by reacting trimethylolpropane with isophorone diisocyanate, compounds formed by reacting 1,6-hexanediol with hexamethylene diisocyanate, and the like.

[0114] From the viewpoint of forming a sufficient crosslinked structure, the isocyanate compound is preferably a trifunctional isocyanate compound. The isocyanate compound is more preferably an adduct that is a reaction product of an isocyanate monomer and a trifunctional compound containing low-molecular-weight active hydrogen, and a urethane body. The isocyanate compound is preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a urethane body of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, a urethane body of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate, a urethane body of isophorone diisocyanate, and more preferably a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of toluene diisocyanate, a trimethylolpropane adduct of isophorone diisocyanate.

[0115] Examples of the epoxy compound include glycerol diglycidyl ether, 1,6-hexanediol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidylaminophenylmethane, and the like.

[0116] Examples of the aziridine compound include N,N'-diphenylmethane-4,4'-bis(1-carbonylaziridine), tri-2,4,6-(1-aziridinyl)-1,3,5-triazine, 4,4'-bis(methyleneiminocarbonylamino)diphenylmethane, and the like.

[0117] The carbodiimide compound is preferably a high-molecular-weight polycarbodiimide formed by a decarbonylation condensation reaction of a diisocyanate compound in the presence of a carbodiimidization catalyst. Commercially available products of the high-molecular-weight polycarbodiimide are preferably the Carbodilite series of Nisshinbo Industries, Inc. Among them, Carbodilite V-03, 07, and 09 are preferably used because of their excellent compatibility with organic solvents.

[0118] Metal chelates are preferably, for example: coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium with acetylacetone or ethyl acetoacetate. Examples of metal chelates include: aluminum ethylacetoacetate-diisopropanolate, aluminum triacetylacetonate, aluminum bis(ethylacetoacetate)-monoacetylacetonate, and aluminum alkylacetoacetate-diisopropanolate.

[0119] Relative to 100 parts by mass of the copolymer (A), it is preferably to contain 0.01 part by mass to 1.0 part by mass of a hardener, and more preferably to contain 0.03 part by mass to 0.5 part by mass of a hardener. If the content is 0.01 part by mass or more, the cohesion is further improved, and if the content is 4 parts by mass or less, it is easy to balance cohesion and flexibility, so it is preferred.

[0120] (Antistatic agent)

[0121] Within the range that does not interfere with the effects of the present invention, the acrylic adhesive of the present specification may contain an antistatic agent. If an antistatic agent is contained, the attachment of dust or dirt can be reduced when the release film is peeled off from the adhesive sheet. On the other hand, there is a concern that the adhesive force to the adherend may be impaired. When in use, it is important to balance the dust-proof property and the adhesive force by the type and amount of the antistatic agent.

[0122] Examples of antistatic agents include: inorganic salts, ionic liquids, ionic solids, surfactants, etc. Among these, ionic liquids are preferred. In addition, "ionic liquids" are also called room-temperature molten salts and show liquid properties at 25°C.

[0123] Examples of inorganic salts include: sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate, sodium carbonate, and sodium thiocyanate, etc.

[0124] Ionic liquids are salts of cations and anions. Examples of cations are preferably imidazolium ions, pyridinium ions, ammonium ions, etc.

[0125] Examples of ionic liquids containing imidazolium ions include: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, etc.

[0126] Examples of ionic liquids containing pyridinium ions include: 1-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-methylpyridinium bis(perfluoroethylsulfonyl)imide, and 1-methylpyridinium bis(perfluorobutylsulfonyl)imide, etc.

[0127] Examples of ionic liquids containing ammonium ions include: trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, and tri-n-butylmethylammonium bis(trifluoromethanesulfonyl)imide, etc.

[0128] In addition, known ionic liquids with cations such as pyrrolidinium ions, phosphonium ions, and sulfonium ions can be suitably used.

[0129] Ionic solids, like ionic liquids, are salts of cations and anions, but exhibit solid properties at normal pressure and 25°C. Cations are preferably, for example, alkali metal ions, phosphonium ions, pyridinium ions, ammonium ions, etc.

[0130] Examples of ionic solids containing alkali metal ions include: lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium bis(heptafluoropropylsulfonyl)imide, lithium bis(nonafluorobutylsulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium bis(pentafluoroethylsulfonyl)imide, sodium bis(heptafluoropropylsulfonyl)imide, sodium bis(nonafluorobutylsulfonyl)imide, potassium bis(fluorosulfonyl)imide, potassium bis(trifluoromethylsulfonyl)imide, potassium bis(pentafluoroethylsulfonyl)imide, potassium bis(heptafluoropropylsulfonyl)imide, potassium bis(nonafluorobutylsulfonyl)imide, etc.

[0131] Examples of ionic solids containing phosphonium ions include, for example: tetrabutylphosphonium bis(fluorosulfonyl)imide, tetrabutylphosphonium bis(trifluoromethylsulfonyl)imide, tetrabutylphosphonium bis(pentafluoroethylsulfonyl)imide, tetrabutylphosphonium bis(heptafluoropropylsulfonyl)imide, tetrabutylphosphonium bis(nonafluorobutylsulfonyl)imide, tributylhexadecylphosphonium bis(fluorosulfonyl)imide, tributylhexadecylphosphonium bis(trifluoromethylsulfonyl)imide, tributylhexadecylphosphonium bis(pentafluoroethylsulfonyl)imide, tributylhexadecylphosphonium bis(heptafluoropropylsulfonyl)imide, tributylhexadecylphosphonium bis(nonafluorobutylsulfonyl)imide, tetraoctylphosphonium bis(fluorosulfonyl)imide, tetraoctylphosphonium bis(trifluoromethylsulfonyl)imide, tetraoctylphosphonium bis(pentafluoroethylsulfonyl)imide, tetraoctylphosphonium bis(heptafluoropropylsulfonyl)imide, tetraoctylphosphonium bis(nonafluorobutylsulfonyl)imide, etc.

[0132] Examples of ionic solids containing pyridinium ions include, for example: 1-hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-hexadecyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexadecyl-4-methylpyridinium bis(pentafluoroethylsulfonyl)imide, 1-hexadecyl-4-methylpyridinium bis(heptafluoropropylsulfonyl)imide, 1-hexadecyl-4-methylpyridinium bis(nonafluorobutylsulfonyl)imide, etc.

[0133] Examples of ionic solids containing ammonium ions include, for example: tributylmethyl bis(trifluoromethylsulfonyl)imide, tributylmethyl bis(pentafluoroethylsulfonyl)imide, tributylmethyl bis(heptafluoropropylsulfonyl)imide, tributylmethyl bis(nonafluorobutylsulfonyl)imide, octyltributyl bis(trifluoromethylsulfonyl)imide, octyltributyl bis(pentafluoroethylsulfonyl)imide, octyltributyl bis(heptafluoropropylsulfonyl)imide, octyltributyl bis(nonafluorobutylsulfonyl)imide, tetrabutyl bis(fluorosulfonyl)imide, tetrabutyl bis(trifluoromethylsulfonyl)imide, tetrabutyl bis(pentafluoroethylsulfonyl)imide, tetrabutyl bis(heptafluoropropylsulfonyl)imide, tetrabutyl bis(nonafluorobutylsulfonyl)imide, etc.

[0134] In addition, known ionic solids with cations such as pyrrolidinium ions, imidazolium ions, and sulfonium ions can be suitably used.

[0135] Surfactants can be classified into nonionic, anionic, cationic, and amphoteric types.

[0136] Examples of nonionic surfactants include, for example: glycerol fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amine fatty acid esters, fatty acid diethanolamides, polyether ester amide types, ethylene oxide-epichlorohydrin types, and polyether ester types, etc.

[0137] Anionic surfactants (excluding ionic liquids and ionic solids) include, for example: alkyl sulfonates, alkyl benzene sulfonates, alkyl phosphates, and polystyrene sulfonic acid types, etc.

[0138] Cationic surfactants include, for example: tetraalkylammonium salts, trialkylbenzylammonium salts, and acrylate polymer types containing a quaternary ammonium salt group, etc.

[0139] Amphoteric surfactants include, for example: alkyl betaines and alkyl imidazolium betaines, amino acid type amphoteric surfactants such as higher alkyl aminopropionates, higher alkyl dimethyl betaines, and higher alkyl dihydroxyethyl betaines, etc.

[0140] Antistatic agents are classified as liquids or solids at 25°C.

[0141] Antistatic agents that are liquids at 25°C are more likely to transfer to the interface between the adhesive layer and the adherend compared to solids at 25°C, so it is easier to obtain better antistatic properties.

[0142] In addition, antistatic agents that are solids at 25°C are more likely to exist in the form of islands in the sea-island structure in the adhesive layer compared to liquids at 25°C. As a result, the cushioning property of the adhesive layer is improved, so it is easier to obtain good flexibility.

[0143] Among these, the antistatic agent is preferably 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide or tetrabutylphosphonium bis(trifluoromethanesulfonyl)imide.

[0144] When using an antistatic agent, the surface resistance value of the acrylic adhesive layer in a 23°C - 50% RH atmosphere is preferably 1×10 5 Ω / □ or more and 1×10 10 Ω / □ or less. By blending an appropriate amount of antistatic agent, dustproofness, adhesiveness, and strain adaptability can be highly balanced.

[0145] Regarding the content of the antistatic agent for achieving the above surface resistance value, although it also depends on the structure of the antistatic agent, it is preferably 0.05 parts by mass to 1 part by mass, more preferably 0.1 parts by mass to 0.8 parts by mass, and even more preferably 0.1 parts by mass to 0.5 parts by mass based on 100 parts by mass of the acrylic copolymer (A).

[0146] (Organosilane compound)

[0147] The acrylic pressure-sensitive adhesive of the present invention may further contain an organosilane compound. Examples of the organosilane compound include: alkoxysilane compounds having (meth)acryloyloxy groups such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropyltripropoxysilane, 3-(meth)acryloyloxypropyltributoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane; alkoxysilane compounds having vinyl groups such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane; alkoxysilane compounds having amino groups such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane; alkoxysilane compounds having mercapto groups such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane; alkoxysilane compounds having epoxy groups such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane; 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, hexamethyldisilazane, silicone resins having alkoxysilyl groups in the molecule, etc.

[0148] Per 100 parts by mass of the acrylic copolymer (A), it is preferably to contain 0.01 part by mass to 2 parts by mass of the silane compound, more preferably to contain 0.05 part by mass to 1 part by mass. By containing 0.01 part by mass to 2 parts by mass of the silane compound, it is easy to form an adhesive layer with excellent strain adaptability.

[0149] In the adhesive sheet of the present invention, as long as it is within the range that can solve the problems, various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather stabilizers, plasticizers, fillers, anti-aging agents, antistatic agents, etc. can be contained as optional components.

[0150] <Antistatic-treated release film>

[0151] The antistatic-treated release film includes a release agent layer and an antistatic layer. The release agent layer and the antistatic layer are each independently formed on one or both sides of the substrate.

[0152] The layer structure is not particularly limited. Starting from the side in contact with the adhesive layer, in the case of "release agent layer / antistatic layer / substrate", the dust-proof property of the adhesive sheet can be excellent, and in the case of "release agent layer / substrate / antistatic layer", the winding deviation resistance of the adhesive sheet can be excellent, so it is preferred.

[0153] Depending on the situation, it may also be "release agent layer / antistatic layer / substrate / antistatic layer", etc.

[0154] Furthermore, within the range that does not hinder the effects of the present invention, other layers may also be provided between the respective layers.

[0155] (Substrate)

[0156] As the substrate, there is no particular limitation, and a transparent plastic substrate can be preferably used. As raw materials for the transparent plastic substrate, for example, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resins such as polymethylmethacrylate (PMMA), polycarbonate, triacetyl cellulose, polysulfone, polyarylate, polycycloolefin and other plastic materials can be cited. In addition, the plastic materials can be used alone or in combination of two or more.

[0157] Among the transparent plastic substrates as described above, a transparent plastic substrate with excellent heat resistance, that is, a transparent plastic substrate in which deformation is suppressed or prevented under harsh conditions such as high temperature and high temperature and high humidity can be preferably used. As the transparent plastic substrate, a PET film or a PEN film or a PET sheet or a PEN sheet is particularly preferred.

[0158] The thickness of the transparent plastic substrate is not particularly limited. For example, it is preferably 10 μm to 200 μm, more preferably 25 μm to 150 μm.

[0159] (Release agent layer)

[0160] The release agent layer is formed of a release agent. As the release agent, generally, silicone-based, fluorine-based, olefin-based, alkyd-based, long-chain alkyl-based, etc. can be cited. In the present invention, a silicone-based release agent is used in the sense of making the range of the release strength large.

[0161] The main component of the release agent of the present invention is linear silicone, and the content rate of branched silicone is 1 mass% or less.

[0162] The silicone-based release agent includes silicone having a siloxane bond in the main chain. As the silicone, for example, various silicones with different release properties can be obtained by combining a type (M unit) in which three organic substituents are bonded to silicon and having one oxygen atom, a type (D unit) in which two organic substituents are bonded to silicon and having two oxygen atoms, a type (T unit) in which one organic substituent is bonded to silicon and having three oxygen atoms, and a type (Q unit) in which no organic substituent is bonded to silicon and having four oxygen atoms, and the release strength can be controlled by the ratio of these. Most can be adjusted in the direction of reducing release using linear silicone containing M units and D units, and can be adjusted in the direction of increasing release using branched silicone containing T units or Q units in the structure of the linear silicone.

[0163] As the linear silicone, a composition mainly composed of D units and appropriately having M units for adjusting the molecular weight is preferred. The organic substituent represents a hydrogen atom, a hydroxyl group, an alkyl group, or an aryl group, and from the viewpoint of being easily soluble in an organic solvent, an alkyl group or an aryl group is preferred, and specifically, a methyl group or a phenyl group is preferred.

[0164] The linear silicone imparts various resistances, so a crosslinked structure can be adopted. The linear silicone preferably has two or more vinyl groups at its terminal and / or side chain as crosslinking points. As the crosslinking agent, there is hydrogen-modified silicone, etc., and it is required to have two or more SiH groups in one molecule.

[0165] Relative to 100 parts by mass of the linear silicone, it is preferably to contain 0.1 part by mass to 20 parts by mass of the hydrogen-modified silicone.

[0166] As the branched silicone, it preferably has T units and / or Q units, and preferably, the T units and / or Q units are 70 mass% or more in 100 mass% of the branched silicone. In addition to having T units and / or Q units, the branched silicone may also have M units and D units.

[0167] The release agent layer is formed from a release agent. The release agent of the present invention contains linear silicone and branched silicone at a ratio of linear silicone:branched silicone = 100:0 to 99:1 (mass ratio). By setting the content of the branched silicone to 1% by mass or less relative to the total mass of the release agent (linear silicone, hydrogen-modified silicone, and branched silicone), the dust-proof property or the resistance to winding deviation is improved. The ratio of the branched silicone is more preferably 0.5% by mass or less, and still more preferably 0.2% by mass or less.

[0168] In 100% by mass of the total mass of the release agent, the total content rate of the linear silicone, hydrogen-modified silicone, and branched silicone is preferably 50% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, and still more preferably 90% by mass to 100% by mass.

[0169] As a method for synthesizing the silicone-based release agent, there are addition reaction, peroxide condensation reaction, and ultraviolet crosslinking reaction, but it is preferably formed by the addition reaction. The addition reaction is the crosslinking of the vinyl group contained in the linear silicone and the SiH group contained in the hydrogen-modified silicone.

[0170] When synthesizing the release agent by the addition reaction, a catalyst is included. The catalyst is not particularly limited, and a platinum-based catalyst is preferred, and more preferably chloroplatinous acid, chloroplatinic acid, etc., alcohol compounds, aldehyde compounds of chloroplatinic acid, or complexes of chloroplatinic acid and various olefins.

[0171] In 100% by mass of the total mass of the release agent, the addition amount of the catalyst is preferably 0.01% by mass to 10% by mass, and more preferably 0.2% by mass to 2% by mass.

[0172] In addition to containing linear silicone and branched silicone, the release agent can contain any other appropriate components other than the catalyst within the range that does not impair the effects of the present invention. For example, reaction inhibitors, inorganic fillers, organic fillers, colorants (dyes or pigments, etc.), plasticizers, ultraviolet absorbers, antioxidants, etc. can be cited.

[0173] Regarding the method for forming the release agent layer, it is preferably formed by coating a release agent composition on a release substrate.

[0174] The release agent can contain a solvent when being coated to form the release agent layer. The solvent is not particularly limited, and for example, hydrocarbon solvents such as n-hexane, cyclohexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; alcohol solvents such as methanol, ethanol, and butanol, etc. organic solvents can be cited.

[0175] As a coating method of the release agent, there are microgravure coaters, gravure coaters, etc.

[0176] The release agent can be adjusted to 0.1 g / m 2 ~2.0g / m 2 , preferably 0.5g / m 2 ~1.2g / m 2 The coating is performed in a left-right manner, and a release agent layer is provided by curing.

[0177] As a hardening method, thermal hardening is preferred in order to promote the addition reaction. As a hardening temperature, there is no particular limitation, but it is preferably 80°C or higher and less than 130°C. If it is 80°C or higher, long-term heating is not required for sufficient hardening, and better productivity can be obtained. In addition, if it is less than 130°C, the generation of wrinkles caused by heat can be reduced in the substrate or the peeling substrate.

[0178] The thickness of the release agent layer is not particularly limited, but is preferably 0.1 to 2 μm, and more preferably 0.5 to 1.2 μm. If it is 0.1 μm or more, the release performance can be fully exhibited, and if it is 2 μm or less, winding deviation caused by the release agent layer is less likely to occur.

[0179] (Antistatic layer)

[0180] The release film of the present invention requires an antistatic layer. By forming the antistatic layer on the release film, it is possible to suppress the mixing of dust or dirt into the adhesive layer during the process of peeling or laminating in the lamination step.

[0181] The antistatic layer can be formed by an antistatic agent containing an antistatic component. As the antistatic agent, known materials can be used. As the antistatic component, there is no particular limitation, and for example, a conductive polymer can be cited. As the conductive polymer component, it is preferred to use a water-soluble conductive polymer or a water-dispersible conductive polymer. By using a conductive polymer, the peeling antistatic property based on the antistatic layer can be satisfied. In addition, the conductive polymer is "water-soluble" or "water-dispersible", but by using a crosslinking agent described later (for example, a melamine-based or isocyanate-based crosslinking agent), it can be fixed in the antistatic layer, thereby improving water resistance. By using the water-soluble conductive polymer or the water-dispersible conductive polymer, the surface resistance value of the antistatic layer can be suppressed to a low level, thereby improving dust resistance.

[0182] As the water-soluble conductive polymer, there is no particular limitation, and examples thereof include: polyaniline sulfonic acid, poly(isothianaphthene-2-sulfonate) compounds, (meth)acrylate polymers containing a quaternary ammonium salt, and the like. Further, as the water-dispersible conductive polymer, there is no particular limitation, and examples thereof include polythiophenes doped with polyanions and polyaniline. Among these, as the water-soluble conductive polymer, polyaniline sulfonic acid is preferably used, and as the water-dispersible conductive polymer, polythiophenes doped with polyanions are preferably used.

[0183] Examples of the polythiophenes that can be used as the water-dispersible conductive polymer include: polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-di-dodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutylthiophene). These can be used alone or in combination of two or more. Among them, from the viewpoint of conductivity, poly(3,4-ethylenedioxythiophene) (PEDOT) is preferred.

[0184] As for polythiophenes, the preferred degree of polymerization is 2 to 1000, more preferably 5 to 100. If the degree of polymerization is within the range of 2 to 1000, the conductivity is excellent, and thus the dust-proof property is improved.

[0185] Poly anions are polymers having structural units with anionic groups and function as dopants for polythiophenes. Examples of poly anions include: polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polypropylene sulfonic acid, polymethacrylic acid sulfonic acid, poly(2-acrylamide-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, poly(2-sulfoethyl methacrylate), poly(4-sulfobutyl methacrylate), polymethacryloxybenzenesulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polypropylene carboxylic acid, polymethacrylic acid carboxylic acid, poly(2-acrylamide-2-methylpropane carboxylic acid), polyisoprene carboxylic acid, polyacrylic acid, polysulfonated phenylacetylene, and the like. Among them, from the viewpoints of improving the conductivity and dispersibility of polythiophenes, polystyrene sulfonic acid (polystyrene sulfonic acid, PSS) is preferred. In addition, these may be homopolymers or copolymers of two or more kinds.

[0186] The mass average molecular weight (Mw) of the poly anions is preferably 1000 to 1,000,000, more preferably 2000 to 500,000. If it is within the range of 1000 to 1,000,000, the doping and dispersibility in polythiophenes are excellent, and thus it is preferred.

[0187] As an antistatic layer, for example, in the case of using poly(3,4-ethylenedioxythiophene) (PEDOT) as polythiophenes and using polystyrene sulfonic acid (PSS) as the poly anions that can dope the polythiophenes, PEDOT and PSS interact, and due to being in extremely close proximity, PSS takes away the electrons of PEDOT, enabling the antistatic layer to exhibit conductivity and improving the dust-proof property.

[0188] Examples of commercially available products of polythiophenes doped with poly anions include: the product name "Baytron P" manufactured by Bayer Co., Ltd., which is poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (PEDOT / PSS), the product name "Seplegyda" manufactured by Shin-Etsu Polymer Co., Ltd., the product name "Verazol" manufactured by Soken Chemical & Engineering Co., Ltd., and the like.

[0189] The mass average molecular weight (Mw) in terms of polystyrene conversion of polyaniline sulfonic acid that can be used as a water-soluble conductive polymer component is preferably 5×10 5 Hereinafter, more preferably 3×10 5 Hereinafter. In addition, the mass average molecular weight of these conductive polymers is generally preferably 1×103 Above, more preferably 5×10 3 Above.

[0190] Examples of commercially available products of polyaniline sulfonic acid include those with the trade name "aquaPASS" manufactured by Mitsubishi Rayon Co., Ltd.

[0191] The antistatic layer can be formed from an antistatic agent containing an antistatic component such as a conductive polymer in a known resin. There is no particular limitation on the known resin, and it is preferably a resin containing a polyester resin as a binder. The polyester resin can use a known resin material containing polyester as the main component.

[0192] In addition, as a crosslinking agent, crosslinking agents such as melamine-based, isocyanate-based, and epoxy-based ones used in general resin crosslinking can be appropriately selected and used.

[0193] The usage amount of the conductive polymer is preferably 10 parts by mass to 200 parts by mass, more preferably 25 parts by mass to 150 parts by mass, and still more preferably 40 parts by mass to 120 parts by mass with respect to 100 parts by mass of the binder. When the usage amount of the conductive polymer is 10 parts by mass to 200 parts by mass, more sufficient dustproof properties can be ensured.

[0194] As a method for forming the antistatic layer, a method of coating one or both sides of a substrate film with a coating material (antistatic agent composition) for forming the antistatic layer and drying (or hardening) it can be adopted. As the conductive polymer component for preparing the coating material, a water-soluble conductive polymer or a water-dispersible conductive polymer, or a polyester resin as a binder, can be used. Preferably, a substance in a form where the conductive polymer is dissolved / dispersed in water is used. An aqueous solution or water dispersion of the conductive polymer can be prepared, for example, by dissolving / dispersing a conductive polymer having a hydrophilic functional group in water. Examples of the hydrophilic functional group include: sulfo group, amino group, amide group, imino group, hydroxyl group, mercapto group, hydrazino group, carboxyl group, quaternary ammonium group, sulfate group, phosphate group, etc. The hydrophilic functional group can form a salt.

[0195] The thickness of the antistatic layer is preferably 3 nm to 500 nm, more preferably 3 nm to 100 nm, and still more preferably 3 nm to 50 nm. If the thickness of the antistatic layer is 3 nm to 500 nm, an adhesive sheet with excellent dustproof properties can be formed.

[0196] Regarding the release film, the surface resistance value (Ω / □) measured on the surface of the release agent is 1×10 10 Ω / □ or less, preferably 1×10 9 Ω / □ or less, more preferably 1×10 8 Ω / □ or less, still more preferably 1×10 7Ω / square or less. The surface resistance value is shown as 1×10 10 Ω / square or less, and the release film can preferably be used as a film used in the process of processing or transporting articles that avoid the mixing of dust or dirt due to static electricity.

[0197] The lower limit value of the surface resistance value is not particularly limited, and is preferably 1×10 5 Ω / square or more.

[0198] In addition, the surface resistance value can be calculated based on the surface resistance value measured using a commercially available resistance measuring device in an atmosphere of 23°C - 50% RH.

[0199] As other treatments of the release film, for example, physical treatments such as corona discharge treatment and plasma treatment; chemical treatments such as primer treatment and other suitable surface treatments can be implemented.

[0200] <Manufacture of the Adhesive Sheet>

[0201] The adhesive sheet of the present invention can be manufactured according to the usual manufacturing method of adhesive sheets. For example, it can be produced by the following methods: on the release agent layer side of the release film, an acrylic adhesive as a mixture of an acrylic copolymer (A) and a curing agent, etc. is directly coated so that the thickness after drying becomes a specified thickness to form an adhesive layer, and then another release film is attached; or on the release agent layer sides of two release films, an adhesive is coated so that the thickness after drying becomes a specified thickness to respectively form two adhesive layers, and then the adhesive layers are attached. At least one of the release films used at this time is an antistatic treatment release film, and in the antistatic treatment release film, the surface resistance value of the release agent layer in an atmosphere of 23°C - 50% RH is 1×10 11 Ω / square or less, the main component of the release agent layer is linear silicone, and the content rate of branched silicone is 1 mass% or less. Among them, it is preferable that both release films are the antistatic treatment release films.

[0202] The lower limit of the film thickness of the adhesive layer is 25 μm or more, and the upper limit is not particularly limited. For example, it is preferably 50 μm - 500 μm, and more preferably 50 μm - 200 μm. If the film thickness of the adhesive layer is 25 μm - 500 μm, sufficient cohesion is easily obtained, and strain adaptability and adhesiveness can be highly balanced, so it is preferable.

[0203] In addition, when coating the adhesive, a conventional coater can be used, such as an intaglio roll coater, a reverse roll coater, a kiss roll coater, an immersion roll coater, a bar coater, a knife coater, or a spray coater, etc.

[0204] As the adhesive sheet, it can also be cut to an appropriate width and wound into a roll shape to have the form of a wound adhesive tape.

[0205] "laminate"

[0206] The laminate includes an adherend and an acrylic adhesive layer, and the adhesive layer is formed using the adhesive sheet of the present invention.

[0207] Specifically, for example, the antistatic treatment release film can be peeled off from the adhesive sheet for flexible display of the present invention, and the adhesive layer can be attached to adherends such as a film substrate (cover panel), a touch sensor (including the case where the outermost layer is a transparent conductive layer, a refractive index adjustment layer, and a protective layer), a reinforced metal plate, a polarizing plate, or an optical element to form a laminate.

[0208] Figure 2 shows an example of a schematic cross-sectional view of a laminate that locally represents an example of the use of the adhesive sheet of the present invention. In Figure 2 , 3 is a film substrate, 1 is an adhesive layer 1, and 4 is a polarizing plate.

[0209] In Figure 2 In the laminate shown, the film substrate is attached to the polarizing plate via an adhesive layer containing the adhesive of the present invention. Thus, the adhesive sheet of the present invention can be used in a form in which an acrylic adhesive layer formed of an acrylic adhesive is attached to a film substrate (cover panel) and a polarizing plate.

[0210] The film substrate (cover panel) is not particularly limited, and a transparent plastic substrate or an ultra-thin glass (UTG) substrate can be preferably used. As raw materials for the transparent plastic substrate, for example, acrylic resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polymethyl methacrylate (PMMA), plastic materials such as polycarbonate, polycycloolefin, and polyimide can be cited. In addition, the plastic material or the glass material can be used alone or in combination of two or more.

[0211] When the film substrate (cover panel) is the transparent plastic substrate as described above, a transparent plastic substrate with excellent heat resistance, that is, a transparent plastic substrate in which deformation is suppressed or prevented under harsh conditions such as high temperature and high temperature and high humidity can be preferably used. As the transparent plastic substrate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycycloolefin, and polyimide are particularly preferred.

[0212] The thickness of the film substrate (cover panel) is not particularly limited, and for example, it is preferably 100 μm to 2000 μm, more preferably 200 μm to 1000 μm.

[0213] "flexible display"

[0214] The flexible display includes an optical element and an acrylic adhesive layer, and the adhesive layer is formed using the adhesive sheet of the present invention.

[0215] Due to its flexibility, the flexible display has the resistance to not break even when bent or twisted. As the optical element, there is no particular limitation, and examples thereof include a liquid crystal element, an organic EL element, and the like.

[0216] The optical element is, for example, an image display unit such as an organic electroluminescent element layer (hereinafter referred to as an OLED layer) or a liquid crystal element layer that can be deformed, and is a member that can be bent, folded, or otherwise deformed from a planar state. Such deformation can be either temporary or permanent.

[0217] For example, the OLED layer may have a structure in which an anode, a hole injection / transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode, a sealing material, and an inorganic barrier layer are sequentially laminated on a film substrate. Various materials, layer structures, and manufacturing methods for forming the OLED layer can use known ones.

[0218] The flexible display has an adhesive layer formed using the adhesive sheet of the present invention.

[0219] Specifically, for example, the antistatic treatment release film can be peeled off from the adhesive sheet for flexible displays of the present invention, and the exposed acrylic adhesive layer can be attached to an adherend such as a film substrate or a polarizing plate to form a laminate, and then attached to the optical element via another adhesive layer to manufacture a flexible display.

[0220] Figure 3 shows an example of a schematic cross-sectional view of a display that locally represents an example of the use of the adhesive sheet of the present invention. In Figure 3 3 is a film substrate (cover panel), 1 is an adhesive layer 1, 4 is a polarizing plate, 5 is an adhesive layer 2, 6 is a barrier layer such as silicon nitride, 7 is an organic EL layer, 8 is a support such as polyimide, and 9 is an organic EL unit. In addition, the structure of the display is not limited to Figure 3 .

[0221] In Figure 3 In the shown display, the film substrate (cover panel) can be attached to the polarizing plate via an adhesive sheet including the adhesive layer 1 formed of the adhesive of the present invention, and then attached to the organic EL unit via the polarizing plate adhesive layer (adhesive layer 2) to manufacture a flexible display.

[0222] In addition, it can also be used to form Figure 3The adhesive layer for a polarizing plate (adhesive layer 2) shown. In this case, specifically, for example, an antistatic treatment release film can be peeled off from the pressure-sensitive adhesive sheet for a flexible display of the present invention, and the exposed acrylic pressure-sensitive adhesive layer can be attached to an optical element to form a laminate. Then, another release film is peeled off and attached to a laminate including a polarizing plate or the like, thereby manufacturing a flexible display.

[0223] That is, for example, in Figure 3 the pressure-sensitive adhesive of the present invention can be used for either adhesive layer 1 or adhesive layer 2.

[0224] As for the usage of the display, there is no particular limitation. First, an organic EL TV can be cited, and an organic EL smartphone, an organic EL tablet computer, an organic EL smartwatch, etc. can also be cited.

[0225] [Examples]

[0226] Next, examples are shown to further illustrate the details, but the present invention is not limited by these. In the examples, unless otherwise specified, "parts" means "parts by mass", "%" means "% by mass", and "RH" refers to relative humidity. In addition, the blending amounts in the tables are parts by mass. Further, the blank columns in the tables indicate no blending.

[0227] In addition, the methods for measuring the glass transition temperature, mass average molecular weight of the acrylic copolymer and the acrylic pressure-sensitive adhesive layer, and the surface resistance value of the antistatic treatment release film are as follows.

[0228] <Calculation of the glass transition temperature of the acrylic copolymer and the acrylic pressure-sensitive adhesive layer>

[0229] The glass transition temperature (Tg) of the acrylic pressure-sensitive adhesive layer is measured using a robotic DSC (differential scanning calorimeter, "RDC220" manufactured by Seiko Instruments Inc.). Approximately 2 mg of the sample is placed in an aluminum flat pan, weighed, and then placed in the differential scanning calorimeter. Using an aluminum flat pan of the same type without the sample as a reference, after maintaining at a temperature of 100 °C for 5 minutes, it is rapidly cooled to -120 °C using liquid nitrogen. Then, the temperature is raised at a rate of 5 °C / minute, and the glass transition temperature (Tg, unit: °C) is determined based on the obtained DSC chart.

[0230] <Measurement of the mass average molecular weight of the acrylic copolymer>

[0231] For the determination of the mass average molecular weight (Mw), a gel permeation chromatograph (GPC) "LC-GPC system" manufactured by Shimadzu Corporation was used, and the mass average molecular weight (Mw) was determined by conversion using polystyrene with a known molecular weight as a reference substance.

[0232] Device name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation

[0233] Column: Four GMHXL columns and one HXL-H column, all manufactured by Tosoh Corporation, were connected.

[0234] Mobile phase solvent: Tetrahydrofuran

[0235] Flow rate: 1.0 ml / min

[0236] Column temperature: 40 °C

[0237] <Measurement of surface resistance value of acrylic adhesive layer and antistatic treated release film>

[0238] For the surface of the acrylic adhesive layer and the surface of the release agent layer of the antistatic treated release film, the surface resistance value was measured using Hiresta-UX MCP-HT800 (manufactured by Nittoseiko Analytech Co., Ltd.).

[0239] <Manufacturing example of acrylic copolymer>

[0240] (Acrylic copolymer (A-1))

[0241] In a reaction vessel (hereinafter simply referred to as "reaction vessel") including a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, 100 parts of ethyl acetate, 80 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of butyl acrylate (BA), 3 parts of methyl acrylate (MA), 1 part of acrylic acid (AA), 1 part of 2-hydroxyethylacrylate (HEA), and 0.1 part of 2,2'-azobisisobutyronitrile (hereinafter simply referred to as "AIBN (azobisisobutyronitrile)") as an initiator were charged, and the atmosphere in this reaction vessel was replaced with nitrogen. Then, while stirring under a nitrogen atmosphere, it was heated to 65 °C to start the reaction. Then, the reaction solution was reacted at 65 °C for 4 hours. After the reaction was completed, it was cooled and diluted with ethyl acetate to obtain a solution of an acrylic copolymer (A-1) having a non-volatile component of 30%. The mass average molecular weight of the obtained acrylic copolymer (A-1) was 800,000.

[0242] (Acrylic copolymers (A-2 to A-6))

[0243] Except for changing to the compositions and blending amounts (parts by mass) shown in Table 1, acrylic copolymers (A-2 to A-6) were produced by the same method as the production of the acrylic copolymer (A-1).

[0244] The mass average molecular weights (Mw) of the obtained adhesives (A-1, A-2 to A-6) are shown in Table 1.

[0245] [Table 1]

[0246] Table 1.

[0247]

[0248] The abbreviations in the table are as follows.

[0249] (Monomer (a-1))

[0250] MA: Methyl acrylate (carbon number 1)

[0251] (Monomer (a-2))

[0252] IBXA: Isobornyl acrylate

[0253] (Monomer (a-3))

[0254] 2EHA: 2-Ethylhexyl acrylate (carbon number 8)

[0255] (Monomer (a-4))

[0256] AA: Acrylic acid

[0257] HEA: 2-Hydroxyethyl acrylate

[0258] (Monomer (a-5))

[0259] BA: Butyl acrylate (carbon number 4)

[0260] <Manufacture of antistatic treated release film>

[0261] (Antistatic treated release film (B-1))

[0262] To 100 parts of Vylonal MD-1480 (manufactured by Toyobo Co., Ltd.) as the main adhesive, 70 parts of aquaPASS (manufactured by Mitsubishi Chemical Corporation) as the conductive polymer, 10 parts of a diisopropylamine-blocked hexamethylene diisocyanate-ureate as the crosslinking agent, and 20 parts of oleic acid amide as the lubricant, water was used for dilution while stirring to mix them well, and an antistatic agent was prepared.

[0263] Using a gravure coater, the antistatic agent was coated on a polyethylene terephthalate (PET) film with a thickness of 50 μm so that the dried film thickness became 25 nm, and dried at 140 °C for 2 minutes to form an antistatic layer.

[0264] Next, an addition reaction type silicone having a vinyl content of 5 mol% with respect to 100 parts of the methyl content in the silicone as the main adhesive was made 100 parts, a platinum-based catalyst was made 1 part, and toluene was made 200 parts. These were formulated, stirred, and mixed well to prepare a release agent.

[0265] The addition reaction type silicone contains a linear silicone having two or more vinyls as crosslinking reactive groups and a hydrogen-modified silicone, and the content rate of the branched silicone is 0 mass%.

[0266] Using a gravure coater, the prepared release agent was coated on the antistatic layer so that the dried film thickness became 1 μm, and dried at 120 °C for 2 minutes to form a release agent layer, obtaining an antistatic treated release film (B-1) having a layer structure of substrate / antistatic layer / release agent layer.

[0267] (Antistatic treated release films (B-2, B-3), antistatic treated release film (B'-1))

[0268] Except for changing the release agent as described in Table 2, the release agent was formed in the same manner as the antistatic-treated release film (B-1), and antistatic-treated release films (B-2, B-3) and an antistatic-treated release film (B'-1) having a layer structure including a substrate / antistatic layer / release agent layer were obtained.

[0269] Regarding the release agent, a release agent was obtained in which the addition reaction type silicone contains a linear silicone having two or more vinyl groups as crosslinking reactive groups and a hydrogen-modified silicone, and contains a branched silicone at the content rate described in Table 2 according to the conditions during production.

[0270] (Antistatic-treated release film (B-4))

[0271] The antistatic agent and the release agent were produced in the same manner as the production of the antistatic-treated release film (B-1).

[0272] Using a gravure coater, the antistatic agent was coated on a polyethylene terephthalate (PET) film with a film thickness of 50 μm so that the dried film thickness became 25 nm, and dried at 140 °C for 2 minutes to form an antistatic layer.

[0273] Subsequently, using a gravure coater, the release agent was coated on the surface of the substrate opposite to the antistatic layer so that the dried film thickness became 1 μm, and dried at 120 °C for 2 minutes to form a release agent layer, obtaining an antistatic-treated release film (B-4) having a layer structure including an antistatic layer / substrate / release agent layer.

[0274] In the release agent, the addition reaction type silicone contains a linear silicone having two or more vinyl groups as crosslinking reactive groups and a hydrogen-modified silicone, and the content rate of the branched silicone is 0 mass%.

[0275] (Release film (B'-2))

[0276] The release agent was produced in the same manner as the production of the antistatic-treated release film (B-1).

[0277] Using a gravure coater, the release agent was coated on a polyethylene terephthalate (PET) film with a film thickness of 50 μm so that the dried film thickness became 1 μm, and dried at 120 °C for 2 minutes to form a release agent layer, obtaining a release film (B'-2) having a layer structure including a substrate / release agent layer.

[0278] The compositions, surface resistance values, and layer structures of the release agents of the antistatic-treated release films (B-2 to B-4), the antistatic-treated release film (B'-1), and the release film (B'-2) are shown in Table 2.

[0279] [Table 2]

[0280] Table 2.

[0281]

[0282]

[0283] (Example 1)

[0284] <Preparation of Adhesive>

[0285] To 100 parts by non-volatile content of the acrylic copolymer (A-1), 0.1 part of toluene diisocyanate-trimethylolpropane adduct as a curing agent and 0.2 part of 3-glycidoxypropyltrimethoxysilane (S-1) as an organosilane compound were blended. Further, ethyl acetate was blended so that the non-volatile content became 20%, and the mixture was stirred to obtain an acrylic adhesive.

[0286] <Manufacture of Adhesive Sheet>

[0287] The obtained acrylic adhesive was coated on the release agent layer of the antistatic-treated release film (B-1) (Release film 1) so that the dried thickness became 75 μm, and dried at 110°C for 3 minutes, thereby forming an adhesive layer. Subsequently, the release agent layer of the antistatic-treated release film (B-2) (Release film 2) was laminated on the adhesive layer, and cured for 1 week under the conditions of a temperature of 25°C and a relative humidity of 55% to obtain an adhesive sheet having a structure of "antistatic-treated release film (B-1) / adhesive layer / antistatic-treated release film (B-2)".

[0288] (Examples 2 to 13, Comparative Example 1, Comparative Example 2)

[0289] An acrylic adhesive was obtained in the same manner as in Example 1 except that the types and blending amounts (parts by mass) of the acrylic copolymer, curing agent, antistatic agent, and organosilane compound were changed as shown in Tables 3 and 4. Then, using the release films shown in Tables 3 and 4, an adhesive sheet was manufactured in the same manner as in Example 1.

[0290] <Evaluation of Adhesive Sheet>

[0291] Using the obtained adhesive sheet, the dustproof property, winding deviation resistance, strain adaptability, and adhesive strength were evaluated. The results are shown in Tables 3 and 4.

[0292] In addition, in the production of the laminate, when one side of the release film peeled off from the adhesive sheet is an antistatic-treated release film, the acrylic adhesive layer exposed after peeling off the antistatic-treated release film is attached to the adherend to produce a laminate, and evaluation is carried out. When both sides of the release film are antistatic-treated release films, first, the laminate is produced by sequentially peeling off the antistatic-treated release films (release film 1) with a light peeling force and easy to peel off, and evaluation is carried out.

[0293] <Dustproof property>

[0294] In an environment of a clean room (class 1000), the antistatic-treated release film is peeled off from the produced adhesive sheet and laminated on a base film (cover panel) to form a laminate. Regarding the dustproof property of the obtained laminate, it is measured within an area of 25 cm in width × 100 cm in length using a defect inspection machine.

[0295] [Evaluation criteria]

[0296] ◎: No foreign matters such as dust or dirt are confirmed at all, excellent.

[0297] ○: One foreign matter such as dust or dirt is confirmed, good.

[0298] △: Two or three foreign matters such as dust or dirt are confirmed, no problem in practice.

[0299] ×: Four or more foreign matters such as dust or dirt are confirmed, there is a problem in practice.

[0300] <Winding offset resistance>

[0301] Prepare a sample obtained by cutting the obtained adhesive sheet into a square with a side length of 4 cm, apply a load of 2 kg / cm 2 using a blocking tester, and leave it standing for 24 hours at 40 °C. Then, take out the sample from the tester, leave it standing for 1 hour at 23 °C, and visually evaluate the degree of offset between the antistatic-treated release film and the adhesive layer after curing. The evaluation criteria are as follows.

[0302] [Evaluation criteria]

[0303] ◎: No winding offset occurs at all, excellent.

[0304] ○: A winding offset of 0.1 mm or less occurs, good.

[0305] △: A winding offset occurs within a range exceeding 0.1 mm and being 0.3 mm or less, no problem in practice.

[0306] ×: A winding offset exceeding 0.3 mm occurs, there is a problem in practice.

[0307] <Strain adaptability>

[0308] From the obtained adhesive sheet, the antistatic treatment release film is peeled off from the adhesive layer, and the exposed adhesive layer is laminated on the polyimide film. Subsequently, the antistatic treatment release film on the other side is peeled off from the adhesive layer, and the exposed adhesive layer is laminated on the easily adherable PET film. The laminate is put into an autoclave and maintained at 50 °C for 20 minutes. Then, the laminate is taken out and left standing at 23 °C - 50% RH for 30 minutes, and then a size of 70 mm in width and 100 mm in length is prepared to obtain a test laminate including the easily adherable PET film / adhesive layer / polyimide.

[0309] Subsequently, in an atmosphere of 25 °C and 50% RH, the test laminate is twisted to the left and right using a flat body unloaded torsion testing machine (manufactured by Yuasa System Machine Co., Ltd.), and then restored to the state before twisting. This is set as one cycle and repeated 200,000 times. The test is carried out with N = 5, and the appearance after the test is evaluated. The evaluation criteria are as follows.

[0310] [Evaluation criteria]

[0311] ◎: No generation, floating / peeling of bubbles are confirmed at all in all five times, excellent.

[0312] ○: Generation, floating / peeling of bubbles are slightly confirmed only once, good.

[0313] △: Generation, floating / peeling of bubbles are slightly confirmed at a frequency of two or three times, no problem in practical use.

[0314] ×: Generation, floating / peeling of bubbles are slightly confirmed at a frequency of four or more times, or generation, floating / peeling of bubbles are clearly confirmed once, there is a problem in practical use.

[0315] <Adhesion>

[0316] From the obtained adhesive sheet, the antistatic treatment release film is peeled off from the adhesive layer, and the exposed adhesive layer is laminated on the easily adherable PET film. Subsequently, the antistatic treatment release film on the other side is peeled off from the adhesive layer, and the exposed adhesive layer is laminated on the polyimide film. The obtained easily adherable PET film / adhesive layer / polyimide is prepared in a size of 25 mm in width and 100 mm in length as a measurement specimen. Subsequently, in an atmosphere of 23 °C - 50% RH, it is pressed once back and forth using a 2 kg roller. Then, it is left standing at 23 °C for 24 hours. Using a tensile testing machine, the adhesion between the adhesive layer and the polyimide is measured under the conditions of 23 °C environment, a peeling speed of 300 mm / minute, and a peeling angle of 180°. The evaluation criteria are as follows.

[0317] [Evaluation Criteria]

[0318] ◎: Above 20 N / 25 mm, excellent.

[0319] ○: Above 15 N / 25 mm and less than 20 N / 25 mm, good.

[0320] △: Above 10 N / 25 mm and less than 15 N / 25 mm, no problem in practical use.

[0321] ×: Less than 10 N / 25 mm, there is a problem in practical use.

[0322] [Table 3]

[0323] Table 3.

[0324]

[0325]

[0326] [Table 4]

[0327] Table 4

[0328]

[0329] The abbreviations in the table are as follows.

[0330] <Hardener>

[0331] NCO: Toluene diisocyanate-trimethylolpropane adduct

[0332] <Antistatic agent>

[0333] E-1: 1-Octyl-4-methylpyridinium bis(fluorosulfonyl)imide

[0334] <Organosilane compound>

[0335] S-1: 3-Glycidoxypropyltrimethoxysilane

[0336] From the results of Table 3 and Table 4, it can be confirmed that in addition to good winding offset resistance and antistatic properties, the adhesive sheets of the examples also all have good reel-type bendability. Thus, the laminate and the display using the adhesive sheet of the present invention are excellent in winding offset resistance, antistatic property, and reel-type bendability. Furthermore, the display of the present invention is excellent in convenience and visibility. On the other hand, the adhesive sheets of Comparative Example 1 and Comparative Example 2 do not fully satisfy the above properties.

Claims

1. A pressure-sensitive adhesive sheet for a flexible display, wherein, an acrylic pressure-sensitive adhesive layer is included on a release agent layer of an antistatic-treated release film, the acrylic pressure-sensitive adhesive layer contains an acrylic copolymer (A), and the acrylic copolymer (A) is a copolymer formed by polymerizing a monomer mixture containing at least one of (meth)acrylic acid alkyl ester monomers (a-1) having an alkyl group with 1 or 2 carbon atoms and (meth)acrylic acid alkyl ester monomers (a-2) having an alicyclic structure, the monomer mixture further contains (meth)acrylic acid alkyl ester monomers (a-3) having an alkyl group with 8 to 12 carbon atoms, in 100% by mass of the monomer mixture, the content of the monomer (a-3) is 80% by mass or more, The surface resistance value of the release agent layer in an atmosphere of 23°C - 50% RH is 1×10 11 Ω / square or less, the main component of the release agent layer is linear silicone, and the content of branched silicone is 1% by mass or less, the glass transition temperature of the acrylic pressure-sensitive adhesive layer is -55°C or lower.

2. The adhesive sheet for a flexible display according to claim 1, wherein, The film thickness of the acrylic pressure-sensitive adhesive layer is 50 μm or more.

3. The pressure-sensitive adhesive sheet for a flexible display according to claim 1 or 2, wherein, the acrylic copolymer (A) contains an acrylic copolymer having a mass average molecular weight of 800,000 or more.

4. The adhesive sheet for a flexible display according to claim 1 or 2, wherein, The acrylic pressure-sensitive adhesive layer contains an antistatic agent. The surface resistance value of the acrylic adhesive layer in an atmosphere of 23°C - 50% RH is 1×10 10 Ω / square or less.

5. A method for manufacturing a laminate, the laminate including an adherend and an acrylic pressure-sensitive adhesive layer, the method for manufacturing the laminate includes: a step of peeling the antistatic-treated release film from the pressure-sensitive adhesive sheet for a flexible display according to any one of claims 1 to 4 and attaching the acrylic pressure-sensitive adhesive layer to the adherend.

6. A method for manufacturing a flexible display, the flexible display including an optical element and an acrylic pressure-sensitive adhesive layer, the method for manufacturing the flexible display includes: a step of peeling the antistatic-treated release film from the pressure-sensitive adhesive sheet for a flexible display according to any one of claims 1 to 4 and attaching the acrylic pressure-sensitive adhesive layer to the optical element.

Images