WO2019150729A1

WO2019150729A1 - Adhesive composition and use therefor

Info

Publication number: WO2019150729A1
Application number: PCT/JP2018/043707
Authority: WO
Inventors: 伸幸竹谷; 中村　賢一; 祐介橋本
Original assignee: 東亞合成株式会社
Priority date: 2018-01-30
Filing date: 2018-11-28
Publication date: 2019-08-08
Also published as: JPWO2019150729A1; JP7052810B2

Abstract

[Problem] To provide an adhesive composition which exhibits improved heat resistance. [Solution] An adhesive composition which contains a vinyl polymer (A) and an acrylic adhesive polymer (B), wherein: a first Tg, which is the glass transition temperature of the entirety of an adhesive layer formed from the adhesive composition, is -80 to 10°C, inclusive, and a second Tg, which is the glass transition temperature calculated from a surface layer section obtained by subjecting the adhesive layer to X-ray photoelectron spectroscopic analysis, is at least 30°C higher than the first Tg; and an adhesive sheet, which is obtained by providing an adhesive layer formed to a film thickness of 50 μm from this adhesive composition on a 100μm-thick polyethylene terephthalate film substrate, exhibits a separation strength from glass at 100°C of 4.0N/25mm or higher.

Description

Adhesive composition and use thereof

This specification relates to an adhesive composition and its use.

The pressure-sensitive adhesive (also referred to as pressure-sensitive adhesive) is processed into a form such as a tape or a label, and is used in a wide range of applications. Further, the adherend is also applied to various substances such as plastic, paper, metal, glass and ceramics.

For example, pressure-sensitive adhesives used for display applications are required to have high heat resistance and durability that can prevent floating and peeling from the adherend even under high temperature and high humidity conditions.

From the viewpoint of heat resistance, a pressure-sensitive adhesive composition containing a high molecular weight acrylic polymer and a low molecular weight acrylic polymer is disclosed (Patent Documents 1 and 2). These pressure-sensitive adhesive compositions achieve suppression of lifting and peeling under high temperature and high humidity conditions (90% RH at 60 ° C.) and high temperature conditions (80 ° C.) by combining acrylic polymers having different molecular weights. .

Moreover, even when a plastic substrate is used as an adherend by an adhesive composition containing a specific vinyl polymer and an acrylic adhesive polymer, a high humidity load (95% RH at 60 ° C, 85% at 85 ° C) % RH) is also disclosed that can prevent floating and peeling (Patent Document 3).

JP 2012-41453 A JP 2011-232470 A JP 2014-88549 A

In recent years, however, the required level of heat resistance (durability) has been increasing. For example, an in-vehicle touch panel or the like may be required to have heat resistance with respect to a temperature of about 100 ° C. In addition, in a display having a curvature in consideration of design properties, when the display is bent at a high temperature, heat resistance under a high temperature condition exceeding 100 ° C. is also required.
In addition, for example, when an adhesive sheet is processed on a display, a pressure-sensitive adhesive having a characteristic of being firmly bonded by heating or pressing while being low tack is required from the viewpoint of good handling and reworkability. There is also.

The pressure-sensitive adhesive compositions described in Patent Documents 1 and 2 cannot sufficiently suppress floating and peeling caused by outgas generation from a plastic substrate under high temperature and high humidity conditions. Moreover, even if it was the adhesive composition of patent document 3 on severe conditions exceeding 100 degreeC, it could not be said that it had durability.

The present specification provides a pressure-sensitive adhesive composition having more excellent heat resistance and use thereof.

The present inventors have further improved heat resistance by using a pressure-sensitive adhesive composition having an acrylic pressure-sensitive adhesive polymer as a base polymer component and a specific vinyl polymer as a tackifier component and exhibiting a specific high-temperature adhesiveness. Succeeded in improving. Further, the present inventors have found that the specific combination is low tack and can exhibit high adhesive force by heating or pressurization. The present specification provides the following means.

[1] An adhesive composition containing a vinyl polymer (A) and an acrylic adhesive polymer (B),
The first Tg, which is the glass transition temperature of the entire pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, is −80 ° C. or higher and 10 ° C. or lower.
The second Tg, which is the glass transition temperature calculated from the surface layer portion obtained by X-ray photoelectron spectroscopy of the pressure-sensitive adhesive layer, is 30 ° C. or more higher than the first Tg,
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a thickness of 50 μm formed from the pressure-sensitive adhesive composition on a 100 μm-thick polyethylene terephthalate film substrate, having a peel strength with respect to glass at 100 ° C. of 4.0 N / 25 mm or more. Agent composition.
[2] The pressure-sensitive adhesive composition according to [1], wherein a peel strength of the pressure-sensitive adhesive sheet with respect to glass at 120 ° C. is 0.5 N / 25 mm or more.
[3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the vinyl polymer (A) has a glass transition temperature (Tg) of 60 ° C. or higher and 200 ° C. or lower.
[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the vinyl polymer (A) has a number average molecular weight of 500 or more and 10,000 or less.
[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the second Tg is 40 ° C. or higher.
[6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the acrylic adhesive polymer (B) has a glass transition temperature of −30 ° C. or higher and 10 ° C. or lower.
[7] Any one of [1] to [6], wherein the vinyl polymer (A) is contained in an amount of 0.5 to 60 parts by mass with respect to 100 parts by mass of the acrylic adhesive polymer (B). The pressure-sensitive adhesive composition described.
[8] The acrylic adhesive polymer (B) contains 10% by mass or more of a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms with respect to all the constituent monomers. The pressure-sensitive adhesive composition according to any one of [1] to [7].
[9] A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of [1] to [8].

The pressure-sensitive adhesive composition disclosed herein (hereinafter also referred to as the pressure-sensitive adhesive composition) can exhibit excellent high-temperature durability (heat resistance) even under high-temperature conditions. The pressure-sensitive adhesive product provided with the pressure-sensitive adhesive layer (hereinafter also referred to as the pressure-sensitive adhesive layer) obtained from the pressure-sensitive adhesive composition is used for outgas generated from a plastic base material even under high temperature conditions exceeding 100 ° C. It is possible to suppress the fine foaming phenomenon. In addition, the combination of the vinyl polymer and the acrylic pressure-sensitive adhesive polymer makes it possible to obtain a pressure-sensitive adhesive composition that has low tack and exhibits high pressure-sensitive adhesive force when heated or pressurized.

The present specification is a specific pressure-sensitive adhesive composition containing a vinyl polymer and an acrylic pressure-sensitive adhesive polymer, and has a specific peeling strength at a high temperature and a pressure-sensitive adhesive composition using the pressure-sensitive adhesive composition Regarding processed products.

This pressure-sensitive adhesive composition contains a vinyl polymer (A) and an acrylic pressure-sensitive adhesive polymer (B), and the glass transition of the pressure-sensitive adhesive layer surface layer is caused by segregating the vinyl polymer (A) to the surface layer of the pressure-sensitive adhesive layer. The temperature can be controlled. The pressure-sensitive adhesive product provided with the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition can suppress or avoid a decrease in pressure-sensitive adhesiveness even under high temperature conditions, and can exhibit sufficient heat resistance. it can.

The segregation behavior of the vinyl polymer (A) on the surface of the pressure-sensitive adhesive layer when forming a pressure-sensitive adhesive layer with the present pressure-sensitive adhesive composition is determined by the specific vinyl polymer (A) and the acrylic pressure-sensitive adhesive polymer (B ) And are not completely compatible, but not completely phase separated. Preferably, the vinyl polymer (A) has a lower polarity than the acrylic adhesive polymer (B).

As described above, a vinyl polymer (A) that is not completely compatible with the acrylic adhesive polymer (B) is used for the present adhesive composition. At that time, the degree of segregation can be adjusted by appropriately adjusting the amount of the vinyl polymer (A) used in the pressure-sensitive adhesive composition. If the amount of the vinyl polymer (A) used is too small, segregation on the surface of the pressure-sensitive adhesive layer becomes insufficient, and a sufficient effect may not be obtained. On the other hand, when there is too much usage-amount of a vinyl polymer (A), as a result of phase-separating with an acrylic adhesive polymer (B), there exists a tendency for transparency and adhesive performance of an adhesive layer to fall. In addition, the glass transition temperature, molecular weight, and the like of the vinyl polymer (A) are appropriately adjusted, whereby the glass transition temperature of the surface layer portion of the pressure-sensitive adhesive layer can be adjusted.

Hereinafter, the disclosure of this specification will be described in detail. In the present specification, “(meth) acryl” means acryl and / or methacryl, and “(meth) acrylate” means acrylate and / or methacrylate. The “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group.

This pressure-sensitive adhesive composition contains a vinyl polymer (A) and an acrylic pressure-sensitive adhesive polymer (B). Details of the vinyl polymer (A), the acrylic pressure-sensitive adhesive polymer (B), and the pressure-sensitive adhesive composition containing these will be sequentially described below.

[Vinyl polymer (A)]
The vinyl polymer (A) disclosed in the present specification can be a polymer having a glass transition temperature (Tg) of 30 ° C. or higher and 200 ° C. or lower. 40 degreeC or more may be sufficient as the minimum of Tg, and 50 degreeC or more may be sufficient as it. From the viewpoint of heat resistance, Tg is preferably 60 ° C. or higher, 70 ° C. or higher, 80 ° C. or higher, or 100 ° C. or higher. The upper limit of Tg may be 180 ° C. or lower, 150 ° C. or lower, 120 ° C. or lower, or 100 ° C. or lower. Moreover, although the upper limit and the lower limit can be combined suitably as for the range of Tg, they are 40 degreeC or more and 180 degrees C or less, for example, may be 60 degreeC or more and 150 degrees C or less. In the present specification, a value measured by differential scanning calorimetry (DSC) at a heating rate of 10 ° C./min is adopted as Tg. When the Tg is less than 30 ° C., the Tg of the surface layer portion of the pressure-sensitive adhesive layer is hardly sufficiently high, the adhesive strength to various adherends is not sufficient, and the durability may be inferior. In general, Tg does not exceed 200 ° C. due to restrictions on raw material monomers.

As the monomer constituting the vinyl polymer (A), various vinyl unsaturated compounds having radical polymerizability can be used, for example, (meth) acrylic acid ester compounds, aromatic vinyl compounds, unsaturated compounds. Carboxylic acid, unsaturated acid anhydride, hydroxyl group-containing unsaturated compound, amino group-containing unsaturated compound, amide group-containing unsaturated compound, alkoxyl group-containing unsaturated compound, cyano group-containing unsaturated compound, nitrile group-containing unsaturated compound And maleimide compounds. These compounds may be used alone or in combination of two or more.

Among these, it is preferable that the main component is a (meth) acrylic acid ester compound because appropriate compatibility with the acrylic adhesive polymer can be obtained. The specific amount of the (meth) acrylic acid ester compound in the total monomer composition of the vinyl polymer (A) is, for example, in the range of 10% by mass to 100% by mass, and 30% by mass to 95%. The range may be in the range of 50% by mass or less, or in the range of 50% by mass to 90% by mass. 40 mass% or more may be sufficient as the minimum of the usage-amount, and 50 mass% or more may be sufficient as it. Moreover, 90 mass% or less may be sufficient as the upper limit of usage-amount, and 80 mass% or less may be sufficient.

Examples of (meth) acrylic acid ester compounds include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, amyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylic acid alkyl esters such as (meth) acrylic acid n-dodecyl and (meth) acrylic acid n-octadecyl; (meth) acrylic acid cyclohexyl, (meth) acrylic acid methylcyclohexyl, (meth) acrylic acid tert -Butylcyclohexyl, cyclododecyl (meth) acrylate, (meth) Aliphatic ring-containing (meth) acrylates such as isobornyl acrylate, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate; phenyl (meth) acrylate, Aromatic ring-containing (meth) acrylic acid esters such as benzyl (meth) acrylate are exemplified. These compounds may be used alone or in combination of two or more.

Among these, (meth) acrylic acid can be set at a relatively high Tg, has a high effect of suppressing the lifting and peeling of the pressure-sensitive adhesive sheet, and has good adhesion to an olefinic adherend. Use of methyl and an aliphatic ring-containing (meth) acrylate such as isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate and adamantyl (meth) acrylate Is preferred. The specific use amount of the aliphatic ring-containing (meth) acrylic acid ester is preferably in the range of 10% by mass or more and 90% by mass or less, and 20% by mass with respect to all constituent monomers of the vinyl polymer (A). It is more preferably 80% by mass or less, and further preferably 30% by mass or more and 70% by mass or less.

Examples of aromatic vinyl compounds include styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, vinyl toluene, β-methyl styrene, ethyl styrene, p-tert-butyl styrene, vinyl xylene, vinyl naphthalene, etc. Is mentioned. These compounds may be used alone or in combination of two or more. The specific use amount of the aromatic vinyl compound is preferably in the range of 1% by mass to 40% by mass and more preferably 5% by mass to 30% by mass with respect to all the constituent monomers of the vinyl polymer (A). Preferably, 5 mass% or more and 20 mass% or less are more preferable.

Examples of unsaturated carboxylic acids include (meth) acrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, and monoalkyl esters of unsaturated dicarboxylic acid (maleic acid). , Fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, monoalkyl esters such as citraconic anhydride) and the like. These compounds may be used alone or in combination of two or more.

Examples of the unsaturated acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like. These compounds may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing unsaturated compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. , Mono (meth) acrylates of polyalkylene glycols such as 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol and polypropylene glycol, p-hydroxystyrene, m-hydroxystyrene O-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, o-isopropenylphenol and the like. These compounds may be used alone or in combination of two or more.

Examples of the amino group-containing unsaturated compound include dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, ( 2- (di-n-propylamino) ethyl (meth) acrylate, 2-dimethylaminopropyl (meth) acrylate, 2-diethylaminopropyl (meth) acrylate, 2- (di-n-propyl) (meth) acrylate Amino) propyl, 3-dimethylaminopropyl (meth) acrylate, 3-diethylaminopropyl (meth) acrylate, 3- (di-n-propylamino) propyl (meth) acrylate, and the like. These compounds may be used alone or in combination of two or more.

Examples of the amide group-containing unsaturated compound include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylol (meth) acrylamide and the like. These compounds may be used alone or in combination of two or more.

Examples of the alkoxyl group-containing unsaturated compound include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (n-propoxy) ethyl (meth) acrylate, and (meth) acrylic acid. 2- (n-butoxy) ethyl, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 2- (n-propoxy) propyl (meth) acrylate, 2- (meth) acrylic acid 2- (N-butoxy) propyl and the like. These compounds may be used alone or in combination of two or more.

Examples of the cyano group-containing unsaturated compound include cyanomethyl (meth) acrylate, 1-cyanoethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, 1-cyanopropyl (meth) acrylate, and (meth) acrylic. 2-cyanopropyl acid, 3-cyanopropyl (meth) acrylate, 4-cyanobutyl (meth) acrylate, 6-cyanohexyl (meth) acrylate, 2-ethyl-6-cyanohexyl (meth) acrylate, ( And (meth) acrylic acid 8-cyanooctyl. These compounds may be used alone or in combination of two or more.

Examples of the nitrile group-containing unsaturated compound include (meth) acrylonitrile, ethacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile and the like. These compounds may be used alone or in combination of two or more.

Examples of maleimide compounds include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, Examples thereof include N- (4-methylphenyl) maleimide, N- (2,6-dimethylphenyl) maleimide, N- (2,6-diethylphenyl) maleimide, N-benzylmaleimide, N-naphthylmaleimide and the like. These compounds may be used alone or in combination of two or more.

In addition to the above compounds, dialkyl esters of unsaturated dicarboxylic acids, vinyl ester compounds, vinyl ether compounds and the like can also be used. Examples of the dialkyl ester of unsaturated dicarboxylic acid include dialkyl esters such as maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, and citraconic anhydride. Examples of the vinyl ester compound include methylene aliphatic monocarboxylic acid ester, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl butyrate, vinyl benzoate, vinyl formate, and vinyl cinnamate. Examples of the vinyl ether compound include vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl isobutyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

The number average molecular weight (Mn) of the vinyl polymer (A) can be 500 or more and 10,000 or less. Mn may be 500 or more and 9,000 or less, 500 or more and 8,000 or less, or 1,000 or more and 8,000 or less. When Mn exceeds 10,000, compatibility with the acrylic adhesive polymer (B) may be deteriorated. On the other hand, in order to produce a polymer having Mn of less than 500, there are problems such as the necessity of using a large amount of a polymerization initiator and a chain transfer agent, and a decrease in productivity.

The weight average molecular weight (Mw) of the vinyl polymer (A) can be 1,000 or more and 15,000 or less. Mw may be 1,000 or more and 12,000 or less, may be 1,000 or more and 10,000 or less, and may be 2,000 or more and 10,000 or less. When Mw exceeds 15,000, compatibility with the acrylic adhesive polymer (B) may be deteriorated. On the other hand, in order to produce a polymer having an Mw of less than 1,000, there are problems such as the necessity of using a large amount of a polymerization initiator and a chain transfer agent and a decrease in productivity.

Further, the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the above (Mn) is preferably 3.0 or less from the viewpoint that good adhesive strength is easily obtained. More preferably, it is 2.5 or less, More preferably, it is 2.0 or less, More preferably, it is 1.8 or less. In addition, the weight average molecular weight Mw and the number average molecular weight Mn are standard polystyrene conversion values obtained using gel permeation chromatography (GPC).

The vinyl polymer (A) is not particularly limited with respect to its production method. For example, the vinyl polymer (A) can be prepared by adopting a known radical polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method or an emulsion polymerization method. It can be easily obtained by polymerizing the monomer. In the case of the solution polymerization method, an organic solvent and a vinyl monomer raw material are charged into a reactor, a thermal polymerization initiator such as an organic peroxide or an azo compound is added, and the mixture is heated to 50 to 300 ° C. for copolymerization. As a result, the intended vinyl polymer can be obtained. The vinyl polymer may be used as a solution dissolved in an organic solvent, or may be used by distilling off the solvent by heating under reduced pressure.

The charging method of each raw material including the monomer may be batch initial batch charging in which all raw materials are charged at once, or semi-continuous charging in which at least one raw material is continuously fed into the reactor. A continuous polymerization method in which the raw materials are continuously supplied and the product resin is continuously withdrawn from the reactor may be used.

As the organic solvent used in the solution polymerization method, organic hydrocarbon compounds are suitable, cyclic ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbon compounds such as benzene, toluene and xylene, ethyl acetate and butyl acetate, etc. Esters, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and alcohols such as methyl orthoformate, methyl orthoacetate, methanol, ethanol, isopropanol, etc., and one or more of these can be used. Among these organic solvents, ethyl acetate, butyl acetate, acetone, and methyl ethyl ketone, which have a relatively low boiling point so as to dissolve the vinyl polymer well and facilitate purification, are preferable.

The initiator used in the present specification may be an azo compound, an organic peroxide, an inorganic peroxide, or the like, but is not particularly limited. You may use the redox type polymerization initiator which consists of a well-known oxidizing agent and a reducing agent. Moreover, a well-known chain transfer agent can also be used together.

Examples of the azo compound include 2,2′-azobis (isobutyronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), azocumene, and 2,2′-azobis (2-methylbutyronitrile). ), 2,2′-azobisdimethylvaleronitrile, 4,4′-azobis (4-cyanovaleric acid), 2- (tert-butylazo) -2-cyanopropane, 2,2′-azobis (2,4 , 4-trimethylpentane), 2,2′-azobis (2-methylpropane), dimethyl 2,2′-azobis (2-methylpropionate), and the like.

Examples of the organic peroxide include cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane. 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, cumene hydroperoxide, 2,5-dimethylhexane-2,5-di Hydroperoxide, 1,3-bis [(tert-butylperoxy) -m-isopropyl] benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, diisopropylbenzene peroxide, tert -Butyl cumyl peroxide Decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, bis (tert-butylcyclohexyl) peroxydicarbonate, tert-butylperoxybenzoate, 2,5-dimethyl-2, Examples include 5-di (benzoylperoxy) hexane.

Examples of inorganic peroxides include potassium persulfate, sodium persulfate, and ammonium persulfate.

Examples of redox type polymerization initiators include sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, ferrous sulfate and the like, potassium peroxodisulfate, hydrogen peroxide, tert-butyl hydroper What used an oxide etc. as an oxidizing agent can be used.

In order to adjust the molecular weight of the vinyl polymer (A), a known chain transfer agent may be used as necessary. Chain transfer agents include ethanethiol, butanethiol, dodecanethiol, benzenethiol, toluenethiol, α-toluenethiol, phenethyl mercaptan, mercaptoethanol, 3-mercaptopropanol, thioglycerin, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, α-mercaptoisobutyric acid, methyl mercaptopropionate, ethyl mercaptopropionate, thioacetic acid, thiomalic acid, thiosalicylic acid, octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, n-hexadecyl mercaptan, Examples thereof include n-tetradecyl mercaptan and tert-tetradecyl mercaptan.

The vinyl polymer (A) can also be obtained by continuous polymerization in a temperature range of 180 to 350 ° C. using a stirred tank reactor. In this polymerization method, since a relatively low molecular weight vinyl polymer can be obtained without substantially using a polymerization initiator or a chain transfer agent, a polymer having a high purity is obtained. However, it is preferable because it is advantageous. When the polymerization temperature is lower than 180 ° C., a polymerization initiator and a large amount of chain transfer agent are required for the polymerization reaction, and the obtained copolymer is easily colored and generates an unpleasant odor. On the other hand, when the polymerization temperature exceeds 350 ° C., a decomposition reaction is likely to occur during the polymerization reaction, and the resulting copolymer is colored. Therefore, the transparency of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition containing the polymerization reaction is increased. There is concern about the decline. Furthermore, according to such a polymerization method, a vinyl polymer having a small molecular weight distribution range can be obtained. The polymerization initiator may be optionally used, but is preferably used at about 1% by mass or less based on the total monomers.

[Acrylic adhesive polymer (B)]
The acrylic adhesive polymer (B) disclosed in the present specification is a polymer containing a (meth) acrylic acid ester compound as a main structural unit. The acrylic adhesive polymer (B) is an adhesive polymer having a glass transition temperature (Tg) in the range of −80 ° C. or higher and 10 ° C. or lower, for example. The lower limit of Tg may be −70 ° C. or higher, −60 ° C. or higher, −50 ° C. or higher, or −40 ° C. or higher. The upper limit of Tg may be 0 ° C. or lower, −10 ° C. or lower, −20 ° C. or lower, or −30 ° C. or lower. In addition, the upper and lower limits of the Tg range can be appropriately combined. For example, the range of −70 ° C. to 0 ° C., for example, −60 ° C. to −10 ° C., and -50 ° C to -20 ° C. If Tg is −80 ° C. or higher, a pressure-sensitive adhesive having sufficient cohesive force and good adhesiveness can be obtained. Moreover, if Tg is 10 degrees C or less, favorable level | step difference followability can be provided.

It should be noted that a pressure-sensitive adhesive composition having excellent heat resistance and low tack can be obtained by setting the Tg of the acrylic pressure-sensitive polymer (B) to, for example, −30 ° C. or higher. Further, for example, it is −25 ° C. or higher, for example, −20 ° C. or higher, for example, −15 ° C. or higher, and for example, −10 ° C. or higher.

Furthermore, the weight average molecular weight (Mw) of the acrylic pressure-sensitive adhesive polymer (B) is preferably 100,000 or more from the viewpoint of exhibiting sufficient cohesive force and good adhesiveness. The lower limit value of Mw may be 300,000 or more, 400,000 or more, or 500,000 or more. Further, Mw of 600,000 or more is preferable in terms of further improving heat resistance, 700,000 or more may be used, 750,000 or more may be used, or 800,000 or more may be used. 900,000 or more, or 1,000,000 or more. On the other hand, if Mw is too large, the step following ability tends to be lowered, and the handling in manufacturing may be difficult. Therefore, the upper limit is, for example, 5,000,000 or less. The upper limit may be 3,000,000 or less, 2,000,000 or less, or 1,000,000 or less.

In addition, the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) is, for example, 10.0 or less from the viewpoint that good adhesive strength is easily obtained. Mw / Mn may be 8.0 or less, 7.0 or less, 6.0 or less, or 5.0 or less. In addition, the weight average molecular weight Mw and the number average molecular weight Mn are standard polystyrene conversion values obtained using gel permeation chromatography (GPC).

As the monomer constituting the acrylic pressure-sensitive adhesive polymer (B), (meth) acrylic acid alkyl ester, (meth) acrylic acid alkoxyalkyl, etc. in that an acrylic copolymer having good adhesiveness is obtained. One or two or more of these can be used.

The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms from the viewpoint of adhesiveness. Specific compounds include n-methyl (meth) acrylate, n-ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, ( N-hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, ( Examples thereof include n-decyl (meth) acrylate and lauryl (meth) acrylate. Preferred monomers include n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n- (meth) acrylate. Octyl, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, etc.

The alkoxyalkyl (meth) acrylate is preferably an (alkyl) alkoxyalkyl ester having an alkoxyalkyl group having 2 to 12 carbon atoms from the viewpoint of adhesiveness. Specific compounds include methoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, butoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, (meth ) Butoxyethyl acrylate, methoxybutyl (meth) acrylate, ethoxybutyl (meth) acrylate, butoxybutyl (meth) acrylate, and the like.

The amount of the above (meth) acrylic acid alkyl ester and / or (meth) acrylic acid alkoxyalkyl ester is not particularly limited, but the lower limit is that acrylic resin tends to provide good adhesive performance. 10% by mass or more based on the total constituent monomers of the copolymer, 20% by mass or more, 30% by mass or more, 40% by mass or more It may be 50 mass% or more. Further, the upper limit is 100% by mass or less, 99% by mass, 95% by mass or less, 90% by mass or less, and 80% by mass or less. Also good. The range of the amount used can be set by appropriately combining these upper and lower limits. For example, the range is 10% by mass to 100% by mass, 10% by mass to 99% by mass, 20% by mass to 95% by mass. Also, for example, it may be 30% by mass or more and 90% by mass or less. If it is 10 mass% or more, an adhesive composition provided with favorable adhesive force, initial adhesive force (tack), low temperature adhesiveness, etc. will be obtained.

Among (meth) acrylic acid alkyl esters, (meth) acrylic acid alkyl esters having an alkyl group having 1 to 3 carbon atoms can be used. By using such an alkyl ester of (meth) acrylic acid, the Tg of the acrylic pressure-sensitive adhesive polymer (B) can be improved, which is advantageous for improving the heat resistance of the pressure-sensitive adhesive layer. Preferably, it is a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 2 carbon atoms, and more preferably methyl (meth) acrylate.

In addition to the above (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester, the acrylic pressure-sensitive adhesive polymer (B) can be copolymerized with other monomers as long as the adhesiveness is not impaired. The body can be used.

Examples of other vinyl monomers include α, β-ethylenically unsaturated carboxylic acid monomers such as (meth) acrylic acid, itaconic acid, maleic acid and fumaric acid; styrene, α-methylstyrene, vinyl Aromatic vinyl monomers such as toluene; cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate Aliphatic vinyl monomers such as itaconic acid monoethyl ester, fumaric acid monobutyl ester and other monoalkyl esters of unsaturated dicarboxylic acids; (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3- Hydroxypropyl, 4-hydroxybutyl (meth) acrylate, polyethylene glycol Hydroxyl-containing monomers such as ru (meth) acrylate, polypropylene glycol (meth) acrylate and polyethylene-polypropylene glycol mono (meth) acrylate; acrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-methoxybutylacrylamide, etc. Ethylenically unsaturated carboxylic acid amides and N-substituted compounds; unsaturated alcohols such as allyl alcohol; (meth) acrylonitrile, vinyl acetate, glycidyl (meth) acrylate, diacetone acrylamide, etc., one of these Or 2 or more types can be used.

In addition, a polyfunctional polymerizable monomer having two or more polymerizable functional groups such as a (meth) acryloyl group and an alkenyl group in the molecule may be used. The polyfunctional polymerizable monomer also acts as a so-called crosslinking agent, and by using this, a crosslinked structure can be formed in the present adhesive polymer.

Polyfunctional (meth) acrylate compounds include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di ( Di (meth) acrylates of dihydric alcohols such as (meth) acrylate; trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri ( Poly (meth) acrylates such as tri (meth) acrylates and tetra (meth) acrylates of trihydric or higher polyhydric alcohols such as (meth) acrylates and pentaerythritol tetra (meth) acrylates And the like can be given Relate.

Examples of polyfunctional alkenyl compounds include polyfunctional allyl ether compounds such as trimethylolpropane diallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, tetraallyloxyethane, and polyallyl saccharose; polyfunctional allyl compounds such as diallyl phthalate; methylene Examples thereof include bisamides such as bisacrylamide and hydroxyethylenebisacrylamide; polyfunctional vinyl compounds such as divinylbenzene.

Examples of the compound having both (meth) acryloyl group and alkenyl group include allyl (meth) acrylate, isopropenyl (meth) acrylate, butenyl (meth) acrylate, pentenyl (meth) acrylate, (meth) acrylic acid. 2- (2-vinyloxyethoxy) ethyl and the like can be mentioned.

The acrylic adhesive polymer (B) can also be obtained by a known radical polymerization method such as a solution polymerization method, a suspension polymerization method or an emulsion polymerization method.

In addition, the acrylic adhesive polymer (B) can be obtained from an acrylic adhesive polymer syrup. In this case, the acrylic adhesive polymer syrup contains a polymer component which is a part of the acrylic adhesive polymer (B) and a (meth) acrylic monomer constituting the remainder of the acrylic adhesive polymer (B). can do. The acrylic adhesive polymer (B) is obtained by applying energy such as heat or active energy rays to the acrylic adhesive polymer syrup and polymerizing the monomer component contained in the syrup.

[Adhesive composition]
This adhesive composition can contain a vinyl polymer (A) and an acrylic adhesive polymer (B). The vinyl polymer (A) has appropriate compatibility with the acrylic adhesive polymer (B). For this reason, the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition containing them exhibits good transparency, and the vinyl polymer (A) partially segregates in the pressure-sensitive adhesive layer, and the vinyl polymer (A ) May be higher than other portions.

As described above, when the vinyl polymer (A) concentration in the surface layer of the pressure-sensitive adhesive layer is higher than others, the pressure-sensitive adhesive layer in the vicinity of the adhesive interface has a relatively high Tg. Can exhibit excellent adhesiveness. Furthermore, since the Tg of the pressure-sensitive adhesive layer as a whole is low and sufficiently flexible, it has excellent stress relaxation properties, and therefore it is possible to suppress inconveniences such as displacement and peeling from the adherend.

In addition to the segregation behavior of the vinyl polymer (A) in the present pressure-sensitive adhesive composition, the difference in Tg between the surface layer of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer as described below is the difference between the vinyl polymer (B) and the acrylic polymer (B). In addition to the blending ratio of A), the monomer composition (polarity) and molecular weight of the vinyl polymer (A), it can be adjusted by appropriately setting Tg, Mw / Mn, and the like.

This pressure-sensitive adhesive composition can contain 0.5 parts by mass or more and 60 parts by mass or less of the vinyl polymer (A) in terms of solid content with respect to 100 parts by mass of the acrylic adhesive polymer (B). . The minimum of preferable content is 1 mass part or more, More preferably, it is 3 mass parts or more, More preferably, it is 4 mass parts or more. Moreover, the upper limit of preferable content is 50 mass parts or less, More preferably, it is 40 mass parts or less, More preferably, it is 30 mass parts or less. Moreover, the range of preferable content is 1 to 40 mass parts, More preferably, it is 3 to 30 mass parts. When the amount of the vinyl polymer (A) used is less than 0.5 parts by mass, the segregation of the vinyl polymer (A) in the pressure-sensitive adhesive layer is insufficient, and particularly satisfactory results cannot be obtained in high-temperature adhesiveness. There is. On the other hand, when it exceeds 60 parts by mass, the vinyl polymer (A) is excessively segregated, and as a result, the step following property and the adhesiveness including tack may be insufficient. Moreover, it may phase-separate with an acrylic adhesive polymer (B), and the transparency of an adhesive layer may fall.

In addition, as will be described later, a pressure-sensitive adhesive composition excellent in low tack and heat resistance can be obtained by using the vinyl polymer (A) in an amount of 10 parts by mass or more. Although it does not specifically limit, heat resistance, adhesiveness, and low tack property are demonstrated by making the compounding quantity of the vinyl polymer (A) with respect to 100 mass parts of acrylic adhesive polymers (B) 10 mass parts or more. Can be

[Crosslinking agent]
The pressure-sensitive adhesive composition can contain a crosslinking agent. The cross-linking agent is not necessarily required, but addition of the cross-linking agent is considered depending on the intended adhesive properties and the form of the present pressure-sensitive adhesive composition, for example, whether it is an emulsion form or a solution form. By containing a cross-linking agent, the cohesive strength and adhesive strength of the pressure-sensitive adhesive layer obtained from the present pressure-sensitive adhesive composition are adjusted, and further, adhesion at high temperatures and high humidity and adhesion to curved surfaces are imparted. be able to. As a crosslinking agent, an epoxy compound having two or more epoxy groups, an isocyanate compound having two or more isocyanate groups, an aziridine compound having two or more aziridinyl groups, an oxazoline compound having an oxazoline group, a metal chelate compound, a butylated melamine compound Etc. Among these, it is preferable to use an aziridine compound, an epoxy compound, and an isocyanate compound.

Examples of the aziridine compound include 1,6-bis (1-aziridinylcarbonylamino) hexane, 1,1 ′-(methylene-di-p-phenylene) bis-3,3-aziridylurea, 1,1 ′. -(Hexamethylene) bis-3,3-aziridylurea, ethylenebis- (2-aziridinylpropionate), tris (1-aziridinyl) phosphine oxide, 2,4,6-triaziridinyl-1,3,5 -Triazine, trimethylolpropane-tris- (2-aziridinylpropionate) and the like.

Examples of the epoxy compound include bisphenol A epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl. Ether, 1,6-hexanediol diglycidyl ether, diglycidylaniline, tetraglycidylxylenediamine, N, N, N ′, N′- tetraglycidyl-m- xylylenediamine, 1,3-bis (N, N— Diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol Polyfunctional glycidyl compounds such as polyglycidyl ether and sorbitol polyglycidyl ether are listed.

As the isocyanate compound, a compound having two or more isocyanate groups is preferably used. As the isocyanate compound, aromatic, aliphatic, and alicyclic isocyanate compounds, and modified products (such as prepolymers) of these isocyanate compounds can be used.

Examples of aromatic isocyanates include diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI). And tolidine diisocyanate (TODI). Examples of the aliphatic isocyanate include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and lysine triisocyanate (LTI). Examples of the alicyclic isocyanate include isophorone diisocyanate (IPDI), cyclohexyl diisocyanate (CHDI), hydrogenated XDI (H6XDI), and hydrogenated MDI (H12MDI). The modified isocyanate includes urethane modified products, dimers, trimers, carbodiimide modified products, allophanate modified products, burette modified products, urea modified products, isocyanurate modified products, oxazolidone modified products, isocyanates. Examples thereof include base end prepolymers.

The content of the crosslinking agent is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the acrylic adhesive polymer (B). A more preferable lower limit is 0.03 parts by mass or more, and further preferably 0.05 parts by mass or more. Moreover, a more preferable upper limit is 5 parts by mass or less, and further preferably 2 parts by mass or less. A more preferable range is 0.03 parts by mass or more and 5 parts by mass or less, and a further preferable range is 0.05 parts by mass or more and 2 parts by mass or less.

[Tg of first pressure-sensitive adhesive layer formed from the present pressure-sensitive adhesive composition (first Tg)]
The glass transition temperature (Tg) of the entire pressure-sensitive adhesive layer (this pressure-sensitive adhesive layer) formed from the present pressure-sensitive adhesive composition, that is, the first Tg can be in the range of −80 ° C. or higher and 10 ° C. or lower. The lower limit of Tg may be −70 ° C. or higher, −60 ° C. or higher, −50 ° C. or higher, or −40 ° C. or higher. Further, the upper limit of Tg may be 0 ° C. or lower, −10 ° C. or lower, −20 ° C. or lower, or −30 ° C. or lower. In addition, the upper and lower limits of the Tg range can be appropriately combined. For example, the range of −70 ° C. to 0 ° C., for example, −60 ° C. to −10 ° C., and -50 ° C to -20 ° C. When the first Tg is less than −80 ° C., the cohesive force of the obtained pressure-sensitive adhesive layer tends to be insufficient, and the curved surface adhesion tends to deteriorate. When it exceeds 10 ° C., the step following property and the low temperature condition The adhesive strength below may not be sufficient. The Tg of the present pressure-sensitive adhesive composition can be obtained by DSC using a temperature increase rate of 10 ° C./min and a nitrogen atmosphere as a measurement atmosphere.

The glass transition temperature of the entire pressure-sensitive adhesive layer is obtained by a known method using a pressure-sensitive adhesive layer obtained from a pressure-sensitive adhesive composition containing a vinyl polymer (A) and an acrylic pressure-sensitive adhesive polymer (B) as a sample. Means the glass transition temperature. In the case where the pressure-sensitive adhesive composition is in the form of a solution or dispersion, the pressure-sensitive adhesive layer can be obtained, for example, by volatilizing and removing the medium by applying the pressure-sensitive adhesive composition and then drying it. In the case where the pressure-sensitive adhesive composition contains a polymerizable compound such as a polymer syrup, it can be obtained by polymerizing the polymerizable compound by irradiating active energy rays such as ultraviolet rays.

[Tg calculated from the composition of the surface layer portion of the pressure-sensitive adhesive layer (second Tg)]
The second Tg of the pressure-sensitive adhesive layer, that is, the X-ray photoelectron spectroscopy of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is obtained by drying or irradiation with active energy rays after coating the pressure-sensitive adhesive composition on the separator. Tg calculated from the composition of the surface layer portion obtained by analysis is calculated from the composition ratio of the vinyl polymer (A) and acrylic adhesive polymer (B) obtained from X-ray photoelectron spectroscopy (XPS). It is calculated | required and can be taken as Tg of the composition which forms the surface layer from the surface of an adhesive layer to this depth of about 5 nm. The details of the measurement method can follow the operations described in the examples described later.

The second Tg is not particularly limited, but is preferably 0 ° C. or higher. When the second Tg is 0 ° C. or more, a Tg difference described below can be easily obtained. As a result, the high-temperature adhesiveness and durability of the adherend can be secured together with the curved surface adhesiveness. The second Tg is more preferably 10 ° C. or higher, further preferably 30 ° C. or higher, still more preferably 40 ° C. or higher, still more preferably 50 ° C. or higher, and even more preferably 60 ° C. or higher. . In addition, 2nd Tg can be suitably adjusted with Tg, a compounding ratio, etc. of a vinyl polymer (A).

[Difference between Tg (first Tg) of the entire pressure-sensitive adhesive layer and Tg (second Tg) calculated from the composition of the surface layer portion of the pressure-sensitive adhesive layer]
In the present pressure-sensitive adhesive composition, the second Tg (Tg calculated from the composition of the surface layer portion of the pressure-sensitive adhesive layer) is 30 ° C. or more higher than the first Tg (Tg of the whole pressure-sensitive adhesive layer). Is preferred. According to the pressure-sensitive adhesive layer having such a Tg composition, the higher the temperature of the pressure-sensitive adhesive layer of the conventional general pressure-sensitive adhesive, the lower the adhesiveness, whereas the high adhesiveness at high temperature (peeling to the adherend) Strength) and high curved surface adhesion.

Further, when the second Tg is higher than the first Tg by 30 ° C. or more, the pressure-sensitive adhesive sheet including the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a complicated shape having a curved surface and uneven portions. It shows good adhesion. In addition, for example, even when the film base material contracts under high temperature conditions, appearance defects such as displacement, peeling or floating are suppressed, and excellent durability is exhibited.

The second Tg is preferably higher than the first Tg by 40 ° C. or more, more preferably 50 ° C. or more, more preferably 60 ° C. or more, still more preferably 65 ° C. or more, and 70 ° C. or more. Even more preferred. The upper limit of the height of the second Tg relative to the first Tg is not particularly limited, but is 280 ° C. from the values that the first Tg and the second Tg can take, and is generally 200 ° C. It is as follows.

[Mass fraction (A / A + B) of vinyl polymer (A) with respect to the total mass of vinyl polymer (A) and acrylic adhesive polymer (B) in the surface layer portion of the pressure-sensitive adhesive layer]
In measuring the second Tg, composition analysis by X-ray photoelectron spectroscopic analysis of the surface layer of the pressure-sensitive adhesive layer is performed. At this time, the mass fraction of the vinyl polymer (A) in the surface layer can be obtained. This mass fraction can be used as an index of the segregation state of the vinyl polymer (A) in the surface layer portion of the pressure-sensitive adhesive layer.

For example, the mass fraction is preferably 55% or more and 95% or less. Within this range, segregation to the surface layer portion of the vinyl polymer (A) occurs, and curved surface adhesion and durability can be obtained even under high temperature and high humidity. More preferably, it is 60% or more, still more preferably 65% or more, still more preferably 70% or more, still more preferably 75% or more, and still more preferably 80% or more. Further, the mass fraction is preferably 90% or less, and more preferably 85% or less.

[Adhesion (peel strength)]
This pressure-sensitive adhesive composition is an adhesive sheet comprising a pressure-sensitive adhesive layer having a thickness of 50 μm formed from the pressure-sensitive adhesive composition on a 100 μm-thick polyethylene terephthalate film substrate, and is bonded to glass at 100 ° C. and a peeling rate of 300 mm / min. The strength is preferably 4.0 N / 25 mm or more. By setting the adhesive strength under a high temperature condition of 100 ° C. to 4.0 N / 25 mm or more, the adhesive strength under the temperature condition is sufficiently high, so that the heat resistance is further improved, and the pressure sensitive adhesive sheet is lifted and peeled off. While preventing, the fine foaming phenomenon derived from the outgas generated from a plastic base material can be suppressed or reduced greatly. More preferably, it is 5.0 N / 25 mm or more, More preferably, it is 6.0 N / 25 mm or more, More preferably, it is 7.0 N / 25 mm or more, More preferably, it is 8.0 N / 25 mm or more.

Further, from the viewpoint of heat resistance, the pressure-sensitive adhesive sheet preferably has an adhesive strength to glass of 0.5 N / 25 mm or more at 120 ° C. and a peeling rate of 300 mm / min. More preferably, it is 1.0 N / 25 mm or more, More preferably, it is 2.0 N / 25 mm or more, More preferably, it is 3.0 N / 25 mm or more.

Here, in producing the pressure-sensitive adhesive sheet, a method of obtaining a pressure-sensitive adhesive sheet by a polymerization reaction in which a pressure-sensitive adhesive composition is directly applied to a PET film substrate and dried or a polymerization initiator is applied, or Any method of transferring to a PET film substrate after coating on a release paper or the like to form an adhesive layer may be adopted. Although drying may be performed at room temperature, from the viewpoint of productivity and the like, usually, it takes several seconds to several tens of minutes under a heating condition of 40 to 150 ° C. using a dryer. A method of drying is common. More specifically, after applying this pressure-sensitive adhesive composition to a 38 μm thick PET film separator so that the thickness after drying becomes 50 μm, the solvent is removed by drying at 80 ° C. for 4 minutes. At the same time, a cross-linking reaction is performed as necessary, and a 38 μm thick PET separator having a peeling force different from that of the separator is bonded and allowed to stand at 40 ° C. for 5 days to obtain an adhesive film sample with a double-sided separator. This can be transferred to a PET film having a thickness of 100 μm that has been subjected to an easy adhesion treatment, whereby a pressure-sensitive adhesive sheet for evaluation can be obtained. Here, the thickness of the pressure-sensitive adhesive layer is preferably 50.0 ± 3.0 μm, more preferably 50.0 ± 2.0 μm, and further preferably 50.0 ± 1.0 μm.

When the evaluation sample is bonded to the glass as the adherend, it is usually pressure-bonded under the conditions of one reciprocation of the 2 kg roller, and the evaluation sample is sufficiently adhered to the glass. In addition, when evaluating a sample with low wettability to the adherend surface, it is pressed onto glass by pressure and / or heat treatment as necessary, and the adhesiveness of the sample is sufficiently developed. It is preferable to perform a test. The pressurizing condition can be about 0.1 to 1.0 MPa (absolute pressure), for example, 0.5 MPa. The heating condition can be about 40 to 150 ° C., for example, 50 ° C. When performing pressurization and / or heat treatment, a desktop pressurization defoaming device described later may be used.

In measuring the peel strength, an adhesive sheet for evaluation was bonded to glass, and pressure bonding was performed for 20 minutes under conditions of 0.5 MPa and 50 ° C. using a desktop pressure defoaming device TBR-200 (manufactured by Chiyoda Electric Co., Ltd.). After that, for example, using a tensile tester with a thermostatic chamber, Strograph R type (manufactured by Toyo Seiki Co., Ltd.) The 180 degree peel strength can be measured to determine the adhesive strength.

The pressure-sensitive adhesive layer of the present pressure-sensitive adhesive composition has high adhesiveness at high temperature to glass as an adherend, but these characteristics are based on the Tg composition (distribution) of the pressure-sensitive adhesive layer. Therefore, high temperature adhesiveness can be provided regardless of the type of material of the adherend.

As already described, according to the present pressure-sensitive adhesive composition, the concentration of the vinyl polymer (A) in the surface layer of the pressure-sensitive adhesive layer is higher than others, and the pressure-sensitive adhesive layer in the vicinity of the adhesive interface has a relatively high Tg. Good adhesiveness can be exhibited even under conditions. A person skilled in the art can prepare a pressure-sensitive adhesive composition having high high-temperature adhesiveness based on the disclosure of the present specification. That is, it can be prepared by appropriately setting the composition of the vinyl polymer (A) and the acrylic adhesive polymer (B), the blending ratio, Tg, molecular weight, molecular weight distribution, etc. of the vinyl polymer (A). .

〔tack〕
In the present pressure-sensitive adhesive composition, as described above, tackiness can be easily controlled. For example, the blending amount of the vinyl polymer (A) with respect to 100 parts by mass of the acrylic adhesive polymer (B) is 10 parts by mass or more, or the Tg of the acrylic adhesive polymer (B) is, for example, −30 ° C. By setting it as the above, low tack property can be exhibited. The tackiness of the present pressure-sensitive adhesive composition can be evaluated according to JISZ0237 with respect to the pressure-sensitive adhesive sheet. The ball number of the ball tack obtained by JISZ0237 is, for example, 3 or less, and can be, for example, 2 or less.

[Transparency (haze value)]
A haze value can be used as an index for evaluating the transparency of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition. As described above, the pressure-sensitive adhesive layer obtained from the present pressure-sensitive adhesive composition has an appropriate compatibility with the acrylic pressure-sensitive adhesive polymer (B). Shows good transparency.

The haze value can be evaluated by the following method, for example. That is, after peeling one separator from the adhesive film sample by this adhesive composition, transferring to a glass plate, and peeling the other separator, it left still on 23 degreeC and 50% RH conditions for one day, and a haze meter Use to measure the haze value. It can be evaluated that the lower the haze value, the better the transparency. A preferred haze value is 2.0 or less. When the haze value is 2.0 or less, it can be said that there is certain preferable transparency. A more preferable haze value is 1.6 or less, still more preferably 1.4 or less, and still more preferably 1.0 or less.

In addition to the vinyl polymer (A) and the acrylic adhesive polymer (B) as a tackifier, this pressure-sensitive adhesive composition is optionally provided with a tackifier, a plasticizer, an antioxidant, an ultraviolet absorber, aging. It can also be set as the composition containing additives, such as an inhibitor, a flame retardant, an antifungal agent, a silane coupling agent, a filler, and a coloring agent.

Tackifiers include rosin derivatives such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin, disproportionated rosin ester; terpene phenol resin, α-pinene, β-pinene, limonene, etc. (Hydrogenated) petroleum resin; coumarone-indene resin; hydrogenated aromatic copolymer; styrene resin; phenol resin; xylene resin; (meth) acrylic polymer.

Examples of the plasticizer include di-n-butyl phthalate, di-n-octyl phthalate, bis (2-ethylhexyl) phthalate, di-n-decyl phthalate, diisodecyl phthalate, and the like; bis (2-ethylhexyl) adipate, di-n Adipic acid esters such as octyl adipate; Sebacic acid esters such as bis (2-ethylhexyl) sebacate; di-n-butyl sebacate; Azelaic acid esters such as bis (2-ethylhexyl) azelate; Paraffins such as chlorinated paraffin Glycols such as polypropylene glycol; epoxy-modified vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; phosphate esters such as trioctyl phosphate and triphenyl phosphate; phosphite esters such as triphenyl phosphite; Ester esters such as esterified products of adipic acid and 1,3-butylene glycol; low molecular weight polymers such as low molecular weight polybutene, low molecular weight polyisobutylene, and low molecular weight polyisoprene; oils such as process oil and naphthenic oil And the like.

Antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5-di- -Tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4, 4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β -(3-tert-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8,10-teto Raoxaspiro [5.5] undecane, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5 -Di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3' -Bis- (4′-hydroxy-3′-tert-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ′, 5′-di-tert-butyl-4′-hydroxybenzyl) -Phenolic antioxidants such as S-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherols; dilauryl 3,3'-thiodip Sulfur-based antioxidants such as pionate, dimyristyl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate; triphenyl phosphite, diphenylisodecyl phosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenylditridecyl) phosphite, cyclic neopentanetetraylbis (octadecylphosphite), tris (nonylphenyl) phosphite, tris (monononylphenyl) phosphite, tris (di Nonylphenyl) phosphite, diisodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl ) -9,10 Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, tris (2,4-di-tert-butylphenyl) phos Phyto, cyclic neopentanetetrayl bis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetrayl bis (2,6-di-tert-butyl-4-methylphenyl) phosphite, Examples thereof include phosphorus antioxidants such as 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite.

Examples of UV absorbers include salicylic acid UV absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate; 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy- 4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy Benzophenone ultraviolet absorbers such as -5-sulfobenzophenone and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane; 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- ( '-Hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'- tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2 ′ -Hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- [2'-hydroxy-3'-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2-methylenebis [ -(1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-5'-methacryloxyphenyl) -2H-benzotriazole 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like; 2-ethylhexyl Cyanoacrylate-based UV absorbers such as -2-cyano-3,3′-diphenyl acrylate and ethyl-2-cyano-3,3′-diphenyl acrylate; nickel bis (octylphenyl) sulfide, [2,2′-thiobis (4-tert-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di- and nickel-based UV stabilizers such as tert-butyl-4-hydroxybenzyl-phosphate monoethylate and nickel-dibutyldithiocarbamate.

Anti-aging agents include poly (2,2,4-trimethyl-1,2-dihydroquinoline), 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 1- (N-phenylamino) ) -Naphthalene, styrenated diphenylamine, dialkyldiphenylamine, N, N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-2-naphthyl-p- Phenylenediamine, 2,6-di-tert-butyl-4-methylphenol, mono (α-methylbenzyl) phenol, di (α-methylbenzyl) phenol, tri (α-methylbenzyl) phenol, 2,2′- Methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6) tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol), 4,4′-thiobis (6-tert-butyl-3-methylphenol), 1,1-bis (4 -Hydroxyphenyl) cyclohexane, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, Examples include nickel dibutyldithiocarbamate, tris (nonylphenyl) phosphite, dilauryl thiodipropionate, distearyl thiodipropionate.

Flame retardants include tetrabromobisphenol A, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, hexabromobenzene, tris (2,3-dibromopropyl) isocyanurate, 2,2-bis Halogen-based flame retardants such as (4-hydroxyethoxy-3,5-dibromophenyl) propane, decabromodiphenyl oxide, halogen-containing polyphosphate; ammonium phosphate, tricresyl phosphate, triethyl phosphate, tris (β-chloroethyl) Phosphorus flame retardants such as phosphate, trischloroethyl phosphate, trisdichloropropyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, acidic phosphate ester, nitrogen-containing phosphorus compounds; red phosphorus, tin oxide, ammonium trioxide Inorganic flame retardants such as Timon, zirconium hydroxide, barium metaborate, aluminum hydroxide, magnesium hydroxide; poly (dimethoxysiloxane), poly (diethoxysiloxane), poly (diphenoxysiloxane), poly (methoxyphenoxysiloxane) Siloxane flame retardants such as methyl silicate, ethyl silicate, and phenyl silicate.

Examples of fungicides include benzimidazole, benzothiazole, trihaloallyl, triazole, organic nitrogen sulfur compounds, and the like.

As silane coupling agents, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (Aminoethyl) -γ-aminopropyltrimethoxysilane and the like.

Examples of the filler include inorganic powder fillers such as calcium carbonate, titanium oxide, mica, and talc; fibrous fillers such as glass fibers and organic reinforcing fibers.

The present adhesive composition is not particularly limited in its form as long as it contains the vinyl polymer (A) and the acrylic adhesive polymer (B). For example, it may be used as a form of a solvent-type pressure-sensitive adhesive composition dissolved in an organic solvent such as ethyl acetate, or a form of an emulsion-type pressure-sensitive adhesive composition in which an acrylic pressure-sensitive adhesive polymer and a tackifier are dispersed in an aqueous medium. It may be used as In the case of a solution-type pressure-sensitive adhesive composition and an emulsion-type pressure-sensitive adhesive composition, the organic solvent or the medium such as water used is usually 20 to 95 parts by weight in a total amount of 100 parts by weight of the pressure-sensitive adhesive composition.

When used as an emulsion-type pressure-sensitive adhesive, a stabilizer can be blended. This stabilizer is used for vinyl chloride such as cadmium stearate, zinc stearate, barium stearate, calcium stearate, lead dibutyltin dilaurate, tris (nonylphenyl) phosphite, triphenylphosphite, diphenylisodecylphosphite, etc. Stabilizer; di-n-octyltin bis (isooctylthioglycolate) salt, di-n-octyltin maleate polymer, di-n-octyltin dilaurate, di-n-octyltin maleate Ester salt, di-n-butyltin bismaleic acid ester salt, di-n-butyltin maleate polymer salt, di-n-butyltin bisoctylthioglycol ester salt, di-n-butyltin β-mercaptopropionate polymer, di -N-Butyl tin dilaure Di-n-methyltin bis (isooctyl mercaptoacetate) salt, poly (thiobis-n-butyltin sulfide), monooctyltin tris (isooctylthioglycolate), dibutyltin maleate, di-n-butyltin maleate ester・ Carboxylates and di-n-butyltin malate esters ・ Organic tin stabilizers such as mercaptides; tribasic lead sulfate, dibasic lead phosphite, basic lead sulfite, dibasic lead phthalate, silica Lead stabilizers such as lead acid, dibasic lead stearate, lead stearate; metal soap stabilizers such as cadmium soap, zinc soap, barium soap, lead soap, composite metal soap, calcium stearate Etc.

In addition to the vinyl polymer (A) and the acrylic pressure-sensitive adhesive polymer (B), the present pressure-sensitive adhesive composition includes a monofunctional and / or polyfunctional (meth) acrylic acid monomer, and By using a composition containing a photopolymerization initiator or the like, the composition may be used as a so-called syrup-type photocurable pressure-sensitive adhesive composition that is cured by active energy rays such as ultraviolet rays.

In the case of a photocurable pressure-sensitive adhesive composition, the composition may contain an organic solvent or the like, but is generally used as a solventless type that does not contain solvents.

Monofunctional (meth) acrylic acid monomers include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms; cyclohexyl (meth) acrylate, dicyclopentyl (meth) acrylate, (meth ) (Meth) acrylic acid esters having a cyclic structure such as isobornyl acrylate; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate Esters; (meth) acrylic acid and the like. These compounds may be used alone or in combination of two or more.

Polyfunctional (meth) acrylic acid monomers include butanediol di (meth) acrylate, hexanediol di (meth) acrylate and other alkylene glycol di (meth) acrylates; triethylene glycol di (meth) acrylate Polyalkylene glycol di (meth) acrylates such as: trimethylolpropane tri (meth) acrylate and its ethylene oxide and / or propylene oxide modified products, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc. Can be mentioned. In addition, a polymer (macromonomer) having a (meth) acryloyl group such as polyurethane (meth) acrylate and polyisoprene-based (meth) acrylate can also be used. Specific examples of the polyisoprene (meth) acrylate include an esterified product of a maleic anhydride adduct of isoprene polymer and 2-hydroxyethyl methacrylate. These compounds may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include benzoin and its alkyl ethers, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones, acylphosphine oxides, α-diketones, and the like. Moreover, in order to improve the sensitivity by an active energy ray, a photosensitizer can also be used together. Examples of the photosensitizer include benzoic acid and amine photosensitizers. These can also be used in combination of two or more. The amount of the photoinitiator and photosensitizer used is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the monofunctional and / or polyfunctional (meth) acrylic acid monomer.

Furthermore, this pressure-sensitive adhesive composition includes the vinyl polymer (A), a monofunctional and / or polyfunctional (meth) acrylic acid monomer, in addition to the photocurable pressure-sensitive adhesive composition described above. Moreover, it can be used also as a photocurable adhesive composition by a composition containing a photoinitiator. The said acrylic adhesive polymer (B) can be mixed with the said photocurable adhesive composition as needed.

[Production of pressure-sensitive adhesive composition]
If this adhesive composition contains a vinyl polymer (A) and an acrylic adhesive polymer (B), there is no special restriction | limiting in the mixing method. For example, this pressure-sensitive adhesive composition may be obtained by mixing a vinyl polymer (A) and an acrylic pressure-sensitive adhesive polymer (B), or an acrylic pressure-sensitive adhesive polymer (B) in the presence of the vinyl polymer (A). ) May be polymerized to obtain the present pressure-sensitive adhesive composition.

This pressure-sensitive adhesive composition can be obtained by adjusting the Tg (first Tg) of the entire pressure-sensitive adhesive layer and the Tg (second Tg) of the surface layer of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is formed. That is, those skilled in the art will realize the adhesiveness of the pressure-sensitive adhesive layer to be finally obtained in order to realize the first Tg, the second Tg, and the temperature difference thereof. Based on the teaching, the present pressure-sensitive adhesive composition can be obtained by appropriately selecting and blending the vinyl polymer (A) and the acrylic pressure-sensitive adhesive polymer (B).

The pressure-sensitive adhesive composition is prepared by, for example, dissolving a vinyl polymer (A) in a solvent such as ethyl acetate to prepare a polymer solution, and adding a polymer of an acrylic pressure-sensitive adhesive polymer (B) to the polymer solution. It can be produced by mixing the solution and, if necessary, mixing a crosslinking agent.

[Use of pressure-sensitive adhesive composition]
The pressure-sensitive adhesive composition of the present invention includes various general pressure-sensitive adhesive products such as pressure-sensitive adhesive films, pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes, pressure-sensitive adhesive tapes, surface protective films, surface protective tapes, masking tapes, electrical insulating tapes, laminates, and the like. In addition, it can be suitably used for bonding when a laminate such as various optical films is constructed.

When applied to the above general pressure-sensitive processed product, after applying the pressure-sensitive adhesive composition of the present invention to one or both surfaces of various substrates, a pressure-sensitive adhesive layer is formed by irradiating active energy rays such as drying or UV, It can be set as an adhesive product such as an adhesive sheet or an adhesive tape. Moreover, the product which has an adhesion layer can also be obtained by making a composition into a molten state, applying to a base material, and cooling. As the substrate, papers, films, cloths, nonwoven fabrics, metal foils, and the like can be used. The pressure-sensitive adhesive composition may be applied directly to these substrates, or applied to a release paper or the like. After being worked and dried, it may be transferred to a substrate. The thickness (thickness after drying) of the pressure-sensitive adhesive formed on the pressure-sensitive adhesive sheet is selected depending on the application, but is usually in the range of 1 to 300 μm, and may be in the range of 5 to 250 μm and in the range of 10 to 200 μm. it can.

Further, by using a glass plate and / or a transparent plastic plate as a base material, an adhesive processed product obtained by bonding a glass plate and / or a transparent plastic plate to one or both sides of the pressure-sensitive adhesive layer can be obtained. Such an adhesive processed product can be applied as a laminate of various optical films and the like. Also in this case, the pressure-sensitive adhesive composition may be applied directly on the substrate, or may be transferred to the substrate after being applied to a release paper and dried.

Since the pressure-sensitive adhesive composition of the present invention is excellent in transparency and peel strength and foam resistance against various adherends under high temperature conditions, such as touch panels, liquid crystal display devices, organic EL display devices, plasma display panels, etc. It is also suitable for bonding a display and various optical films used therefor. Moreover, it is useful also for the adhesive use in electronic components, such as a flexible printed circuit board.

The following are specific examples that embody the disclosure of this specification. However, the disclosure of the present specification is not limited to the following specific examples. In the following description, “part” means part by mass, and “%” means mass%.

Various analyzes in this specification were performed by the methods described below.

<Solid content>
About 1 g of the measurement sample was weighed (a), then the residue after drying at 155 ° C. for 30 minutes in the ventilation dryer was measured (b) and calculated from the following formula. A weighing bottle was used for the measurement. Other operations were in accordance with JIS K 0067-1992 (chemical product weight loss and residue test method).
Solid content (%) = (b / a) × 100

<Molecular weight measurement>
The molecular weight was measured by GPC under the following conditions.
GPC: Tosoh (HLC-8120)
Column: Tosoh (TSKgel-Super MP-M x 4)
Sample concentration: 0.1%
Flow rate: 0.6 ml / min Eluent: Tetrahydrofuran Column temperature: 40 ° C
Detector: Differential refractometer (RI)
Reference material: Polystyrene

<Glass transition point (Tg)>
Tg of the vinyl polymer (A), the acrylic adhesive polymer (B) and the adhesive composition was measured by DSC under the following conditions.
DSC: TA Instrument (Q-100)
Temperature rise: 10 ° C / min Measurement atmosphere: Nitrogen

<Polymer composition>
The polymer composition was calculated from the monomer charge and the monomer consumption by GC measurement.
GC: Made by Agilent Technologies (7820A GC System)
Detector: FID
Column: 100% dimethylsiloxane (CP-Sil 5CB) 30m long, 0.32mm inside diameter
Calculation method: Internal standard method

1. Synthesis Example 1 of Vinyl Polymer (Synthesis of Polymer A-1)
In a four-necked flask with an internal volume of 1 liter, 200 parts by mass of butyl acetate and dimethyl 2,2′-azobis (2-methylpropionate) (trade name “V-601” manufactured by Wako Pure Chemical Industries, Ltd.) 0.9 A liquid mixture consisting of parts by mass was charged, and the liquid mixture was sufficiently degassed by bubbling nitrogen gas, and the internal temperature of the liquid mixture was raised to 90 ° C. Separately, 165 parts by mass of methyl methacrylate (hereinafter referred to as “MMA”), 44 parts by mass of isobornyl methacrylate (hereinafter referred to as “IBXMA”), 17 parts by mass of V-601, and 90 parts by mass of butyl acetate were dropped. Polymerization was carried out by dropping from a funnel into the flask over 5 hours. After completion of the dropping, the polymerization solution was dropped into a mixed solution consisting of 4800 parts by mass of methanol and 1200 parts by mass of distilled water, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-1. The polymer composition of the obtained polymer A-1 was calculated from the charged amount and the monomer consumption by GC measurement, and was composed of 80% by mass of MMA and 20% by mass of IBXMA, and was Mw6700, Mn4370, Mw / Mn1.53. It was. Tg was 108 ° C. The composition of polymer A-1 and the analysis results are shown in Table 1.

Synthesis Example 2 (Polymer A-2)
A four-necked flask with an internal volume of 1 liter is charged with a mixed liquid consisting of 200 parts by mass of butyl acetate and 0.6 part by mass of V-601, and the mixed liquid is sufficiently degassed by bubbling with nitrogen gas. The internal temperature was increased to 90 ° C. Separately, polymerization was carried out by dropping a mixture of MMA 165 parts, IBXMA 43 parts, V-601 11 parts and butyl acetate 90 parts into a flask from a dropping funnel over 5 hours. After completion of the dropwise addition, the polymerization solution was dropped into a mixed solution consisting of 4800 parts by mass of methanol and 1200 parts by mass of distilled water, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-2. The composition and analysis results of the polymer A-2 are shown in Table 1.

Synthesis Example 3 (Polymer A-3)
A four-necked flask with an internal volume of 1 liter is charged with a mixed liquid consisting of 200 parts by weight of butyl acetate and 4.1 parts by weight of V-601, and the mixed liquid is sufficiently degassed by bubbling with nitrogen gas. The internal temperature was increased to 90 ° C. Separately, polymerization was carried out by dropping a mixed solution consisting of 168 parts by mass of MMA, 83 parts by mass of IBXMA, 78 parts by mass of V-601, and 90 parts by mass of butyl acetate into the flask from a dropping funnel over 5 hours. After completion of the dropping, the polymerization solution was added dropwise to a mixed solution consisting of 4800 parts by mass of methanol and 1200 parts by mass of distilled water, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-3. The composition and analysis results of the polymer A-3 are shown in Table 1.

Synthesis Example 4 (Polymer A-4)
A four-necked flask with an internal volume of 1 liter is charged with a mixed solution consisting of 200 parts by mass of butyl acetate and 0.9 part by mass of V-601, and the mixed solution is sufficiently degassed by bubbling with nitrogen gas. The internal temperature was increased to 90 ° C. Separately, polymerization was carried out by dropping a mixed liquid consisting of 60 parts by mass of MMA, 166 parts by mass of IBXMA, 18 parts by mass of V-601, and 90 parts by mass of butyl acetate into the flask from a dropping funnel over 5 hours. After completion of the dropping, the polymerization solution was added dropwise to a mixed solution consisting of 4800 parts by mass of methanol and 1200 parts by mass of distilled water, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-4. The composition and analysis results of the polymer A-4 are shown in Table 1.

Synthesis Example 5 (Synthesis of Polymer A-5)
A four-necked flask with an internal volume of 1 liter was charged with a mixed liquid consisting of 280 parts by mass of butyl acetate and 0.3 part by mass of V-601. The mixed liquid was sufficiently degassed by bubbling with nitrogen gas. The internal temperature was raised to 90 ° C. Separately, polymerization was carried out by dropping a mixed liquid consisting of 233 parts by mass of MMA, 26 parts by mass of IBXMA, 5.1 parts by mass of V-601, and 90 parts by mass of butyl acetate into the flask from a dropping funnel over 5 hours. After completion of the dropping, the polymerization solution was added dropwise to 6000 parts by mass of hexane, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-5. Table 1 shows the composition and analysis results of the polymer A-5.

Synthesis Example 6 (Synthesis of Polymer A-6)
A four-necked flask with an internal volume of 1 liter was charged with a mixed solution consisting of 200 parts by mass of butyl acetate and 6.2 parts by mass of V-601, and this mixture was sufficiently degassed by bubbling nitrogen gas. The internal temperature was raised to 90 ° C. Separately, polymerization was performed by dropping a mixed liquid consisting of 114 parts by mass of MMA, 140 parts by mass of IBXMA, 110 parts by mass of V-601, and 90 parts by mass of butyl acetate into the flask from a dropping funnel over 5 hours. After completion of the dropping, the polymerization solution was added dropwise to a mixed solution consisting of 4800 parts by mass of methanol and 1200 parts by mass of distilled water, whereby the vinyl polymer in the polymerization solution was isolated to obtain a polymer A-6. Table 1 shows the composition and analysis results of Polymer A-6.

2. Synthesis Synthesis Example 7 of Acrylic Adhesive Polymer (Synthesis of Polymer B-1)
To a four-necked flask with an internal volume of 3 liters, methoxyethyl acrylate (hereinafter referred to as “MEA”) (500 parts by mass), 2-hydroxyethyl acrylate (hereinafter referred to as “HEA”) (27 parts by mass), acetic acid Ethyl (980 parts by mass) was charged, the mixture was sufficiently degassed by bubbling nitrogen gas, the internal temperature of the mixture was raised to 75 ° C., and azobisvaleronitrile (hereinafter referred to as “V-65”) (0.25 part by mass) was charged and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-1. The obtained polymer B-1 was composed of 95% by mass of MEA and 5% by mass of HEA, and had Mw 520000, Mn 116000, and Mw / Mn 4.48. Table 2 shows the composition and analysis results of the polymer B-1.

Synthesis Example 8 (Synthesis of Polymer B-2)
MEA (413 parts by mass), HEA (27 parts by mass), butyl acrylate (hereinafter referred to as “BA”) (90 parts by mass), and ethyl acetate (980 parts by mass) were added to a three-liter four-necked flask. The mixture was sufficiently degassed by bubbling nitrogen gas, the internal temperature of the mixture was raised to 75 ° C., V-65 (0.25 part by mass) was charged, and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-2. Table 2 shows the composition and analysis results of the polymer B-2.

Synthesis Example 9 (Synthesis of polymer B-3)
In a four-necked flask with an internal volume of 3 liters, MEA (254 parts by mass), HEA (27 parts by mass), BA (90 parts by mass), methyl acrylate (hereinafter referred to as “MA”) (159 parts by mass), acetic acid Ethyl (980 parts by mass) was charged, the mixture was sufficiently degassed by bubbling nitrogen gas, the internal temperature of the mixture was raised to 75 ° C., and V-65 (0.20 parts by mass) was added to perform polymerization. Started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-3. Table 2 shows the composition and analysis results of the polymer B-3.

Synthesis Example 10 (Synthesis of Polymer B-4)
HEA (27 parts by mass), BA (192 parts by mass), MA (330 parts by mass), and ethyl acetate (1200 parts by mass) are charged into a 3 liter four-necked flask, and this mixture is bubbled with nitrogen gas. The mixture was sufficiently deaerated, the internal temperature of the mixture was raised to 75 ° C., V-65 (0.23 parts by mass) was charged, and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-4. Table 2 shows the composition and analysis results of the polymer B-4.

Synthesis Example 11 (Synthesis of Polymer B-5)
MEA (105 parts by mass), HEA (25 parts by mass), BA (370 parts by mass) and ethyl acetate (930 parts by mass) are charged into a 3 liter four-necked flask and the mixture is bubbled with nitrogen gas. The mixture was sufficiently deaerated, the internal temperature of the mixture was raised to 75 ° C., V-65 (0.24 parts by mass) was charged, and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-5. Table 2 shows the composition and analysis results of the polymer B-5.

Synthesis Example 12 (Synthesis of polymer B-6)
HEA (20 parts by mass), BA (140 parts by mass), MA (240 parts by mass), and ethyl acetate (600 parts by mass) are charged into a 3 liter four-necked flask, and this mixture is bubbled with nitrogen gas. The mixture was sufficiently deaerated, the internal temperature of the mixture was raised to 75 ° C., V-65 (0.10 parts by mass) was charged, and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-6. Table 2 shows the composition and analysis results of Polymer B-6.

Synthesis Example 13 (Synthesis of polymer B-7)
HEA (30 parts by mass), ethyl acrylate (hereinafter referred to as “EA”) (390 parts by mass), MA (180 parts by mass), and ethyl acetate (890 parts by mass) were added to a 3 liter four-necked flask. The mixture was sufficiently degassed by bubbling nitrogen gas, the internal temperature of the mixture was raised to 75 ° C., V-65 (0.15 parts by mass) was charged, and polymerization was started. After 5 hours, ethyl acetate was added to a solid content of 30% by mass to obtain an ethyl acetate solution of polymer B-7. Table 2 shows the composition and analysis results of the polymer B-7.

3. Production and evaluation of pressure-sensitive adhesive composition Example 1
The polymer (A-1) obtained in Synthesis Example 1 was dissolved in ethyl acetate to prepare a polymer (A-1) solution having a solid content concentration of 30% by mass. The polymer (A-1) solution 2 parts by mass, the polymer B-1 solution (100 parts by mass), Takenate D-110N as a crosslinking agent (solid content concentration 75% by mass, manufactured by Mitsui Chemicals) (0.16 mass) Part) was mixed to obtain an adhesive composition.

This pressure-sensitive adhesive composition was applied on a 38 μm-thick polyethylene terephthalate (hereinafter “PET”) separator so that the thickness after drying was 50 μm. By drying the pressure-sensitive adhesive composition at 80 ° C. for 4 minutes, ethyl acetate was removed and a crosslinking reaction was performed, and a PET separator having a thickness of 38 μm different from that of the separator was bonded, and 5 ° C. at 5 ° C. The adhesive film sample with a double-sided separator was obtained by standing for aging and aging (aging).

The obtained adhesive film sample was subjected to various measurements and evaluations by the following methods. The obtained results are shown in Table 3.

<Gel fraction>
0.2 g of adhesive was collected from the adhesive film sample, and the initial weight of the adhesive was weighed. The adhesive was immersed in 50 g of ethyl acetate and allowed to stand at room temperature for 16 hours. Thereafter, the mixture was filtered through a 200 mesh wire mesh, and the residue remaining on the mesh was dried at 80 ° C. for 3 hours and weighed. From the initial weight and the residual weight, the gel fraction based on the acrylic adhesive polymer (B) was calculated by the following formula.
Gel fraction (%) = (weight of residue) / [(initial weight) × (solid content of acrylic adhesive polymer (B)) / (solid content of the entire pressure-sensitive adhesive composition)] × 100

<Transparency (haze value)>
The release film was peeled off from the adhesive film sample, transferred to a glass plate (1 mm thickness), and the other release film was peeled off. After standing at 23 ° C. and 50% RH for 1 day, measuring the haze value by using a haze meter “Haze Meter NDH2000” (model name) manufactured by Nippon Denshoku Co., Ltd. enables transparency in the composition. Evaluated.

Evaluation was made on ball tack using an adhesive film sample. Ball tack was evaluated according to JISZ0237.

<23 ° C peel strength for glass>
The pressure-sensitive adhesive film sample was transferred to a PET film (100 μm) subjected to easy adhesion treatment to obtain a pressure-sensitive adhesive sheet for evaluation. The adherend is a glass plate (manufactured by Asahi Glass Co., Ltd., Fabricech FL11A, 1 mm thickness), the adhesive sheet for evaluation is bonded, and after reciprocating three times with a 2 kg roller, a tensile tester with a thermostatic bath, strograph R type ( 180 ° peel strength of the pressure-sensitive adhesive sheet was measured according to JIS Z-0237 “Testing method for pressure-sensitive adhesive tape / pressure-sensitive adhesive sheet” at 23 ° C. using Toyo Seiki Co.). The peeling speed was 300 mm / min. It was.

<High temperature peel strength for glass>
The pressure-sensitive adhesive film sample was transferred to a PET film (100 μm) subjected to easy adhesion treatment to obtain a pressure-sensitive adhesive sheet for evaluation. The adherend is a glass plate (manufactured by Asahi Glass Co., Ltd., Fabricec FL11A, 1 mm thickness), and the above adhesive sheet for evaluation is bonded to the substrate. After crimping for 20 minutes under conditions of 5 MPa and 50 ° C., using a tensile tester Strograph R type with a thermostatic bath (manufactured by Toyo Seiki Co., Ltd.) under the conditions of 85 ° C., 100 ° C. and 120 ° C. In accordance with 0237 “Testing method of adhesive tape / adhesive sheet”, the 180-degree peel strength of the adhesive sheet was measured and used as the adhesive strength. The peeling speed was 300 mm / min. It was.

<Tg of the surface layer portion of the pressure-sensitive adhesive layer>
From the peak area ratio of O1s and C1s measured by X-ray photoelectron spectroscopy (XPS) of the adhesive film sample, vinyl relative to the total amount of vinyl polymer (A) and acrylic adhesive polymer (B) in the surface layer portion of the adhesive layer Each mass fraction (w _A and w _B ) of the polymer (A) and the acrylic adhesive polymer ( _B ) was calculated, and the Tg of the surface layer portion was calculated based on the FOX equation.
XPS measurement was performed under the following conditions.
Apparatus: PHI5000 VersaProbe manufactured by ULVAC-PHI
X-ray: Al-Kα (1486.6 eV)
X-ray incident angle on sample: 0 ° (angle with respect to normal of sample measurement surface)
Photoelectron detection angle: 45 ° (angle with respect to normal of sample measurement surface)

A specific method for calculating the mass fraction is described below.
The ratio of the number of oxygen atoms and the number of carbon atoms calculated from the peak area ratio of O1s and C1s by XPS measurement is composed of a vinyl polymer (A) and an acrylic adhesive polymer (B) as shown in the following formula (1). It is represented by the ratio of the number of oxygen atoms and the number of carbon atoms present per unit weight of the surface layer part of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition.

here,
(O / C) _{A + B} : Ratio W between the number of oxygen atoms and the number of carbon atoms calculated from the peak area ratio of O1s and C1s determined from the XPS measurement of the pressure-sensitive adhesive layer obtained by drying the pressure-sensitive adhesive composition _A : Mass fraction of vinyl polymer (A) with respect to the total amount of vinyl polymer (A) and acrylic adhesive polymer (B) M _wA : Weighted average molecular weight of all constituent monomer units of vinyl polymer (A) M _wB : Weighted average molecular weight of all constituent monomer units of the acrylic pressure-sensitive adhesive composition (B) N _OA : Included in the average monomer structural formula of all constituent monomers constituting the vinyl polymer (A) Number of oxygen atoms N _OB : Number of oxygen atoms contained in the average monomer structural formula of all constituent monomers constituting the acrylic adhesive polymer (B) N _CA : Total number constituting the vinyl polymer (A) constituent monomer of the average monomer structure carbon atoms contained in the formula N _CB: acrylic based pressure-sensitive Number of carbon atoms contained averaged in the monomer structure of the total constituent monomer constituting the sex polymer (B)

The number of carbon atoms and oxygen atoms calculated from the peak area ratio of O1s and C1s determined by XPS measurement of the film obtained by drying the vinyl polymer (A) and the acrylic adhesive polymer (B) alone The ratio of the numbers is expressed by the following formulas (2) and (3), respectively.

here,
(O / C) _A : Ratio of the number of oxygen atoms and the number of carbon atoms calculated from the peak area ratio of O1s and C1s determined from the XPS measurement of the film obtained by drying the vinyl polymer (A)

here,
(O / C) _B : Ratio of the number of oxygen atoms and the number of carbon atoms calculated from the peak area ratio of O1s and C1s obtained from XPS measurement of the film obtained by drying the acrylic adhesive polymer (B)

The following formula (4) is derived from the above formulas (1) to (3). From this, the mass fraction of the vinyl polymer (A) with respect to the total amount of the vinyl polymer (A) and the acrylic adhesive polymer (B). (W _A ) is calculated.

Furthermore, the mass fraction (W _B ) of the acrylic adhesive polymer ( _B ) is calculated from the value of W _A obtained above and the following formula (5).

here,
W _B : Mass fraction of the acrylic adhesive polymer (B) with respect to the total amount of the vinyl polymer (A) and the acrylic adhesive polymer (B)

About Example 1, each element in the said Formula (4) is shown below.
(O / C) _{A + B} : 0.340 (actual value)
(O / C) _A : 0.290 (actual value)
(O / C) _B : 0.474 (actual value)
N _CA : From the number of carbon atoms in MMA1 molecule (5), the number of carbon atoms in IBXMA1 molecule (14) and the composition ratio, 5 × 89.9 (mol%) + 14 × 10.1 (mol%) = 5. 91
N _CB : 6 × 94.4 (mol%) + 5 × 5.6 (mol%) = 5 from the number of carbon atoms in the MEA molecule (6), the number of carbon atoms in the HEA molecule (5), and the composition ratio. 94
M _wA : From the molecular weight (100) of MMA, the molecular weight (222) of IBXMA, and the composition ratio, 100 × 89.9 (mol%) + 222 × 10.1 (mol%) = 112.3
M _wB : From the molecular weight of MEA (130), the molecular weight of HEA (116) and the composition ratio, 130 × 94.4 (mol%) + 116 × 5.6 (mol%) = 129.2
By substituting these values into equation (4), W _A = 0.703 was obtained, and from equation (5), W _B = 0.297 was obtained.

Next, Tg of the surface layer portion was calculated from the surface composition obtained by the measurement according to the formula of FOX represented by the following formula (6), and a value of 52.5 ° C. was obtained.
1 / [Tg of surface layer portion] (K) = W _A / Tg _A + W _B / Tg _B (6)
here,
Tg _A : Tg of the vinyl polymer (A) (70.3 ° C.)
Tg _B : Tg of acrylic adhesive polymer (B) (−31 ° C.)

<Foaming resistance>
A laminated film in which an easy-adhesive PET film having a thickness of 100 μm was pasted on one side of an adhesive film sample and a polycarbonate plate was pasted on the other side was prepared. The laminated body was subjected to 50 ° C., 0.5 MPa, 20 minutes. A crimping process was performed. Thereafter, a load is applied to each of the laminates at 85 ° C./85% RH for 24 hours using a constant temperature and humidity chamber, or at 100 ° C. for 24 hours using a blow dryer, or at 120 ° C. for 20 minutes, The appearance after loading (whether foaming was present) was visually confirmed and evaluated according to the following criteria.
○: No change in appearance △: Area of the foamed portion is 10% or less with respect to the area of the test piece ×: Area of the foamed portion exceeds 10% with respect to the area of the test piece

(Examples 2 to 9 and Comparative Examples 1 to 3)
In Example 1, the types and ratios of the acrylic pressure-sensitive adhesive polymer and the vinyl polymer were changed as shown in Tables 3 and 4 to obtain a pressure-sensitive adhesive composition, and the same measurements as in Example 1 were performed. The results are shown in Tables 3 and 4.

In Examples 1 to 9 using the pressure-sensitive adhesive composition included in the present invention, the peel strength of the pressure-sensitive adhesive sheet with respect to glass at 100 ° C. is 4.0 N / 25 mm or more (5.4 to 19.1 N / 25 mm), The peel strength at 120 ° C. is 0.5 N / 25 mm (0.6 to 7.1 N / 25 mm) or more. All of these showed good foam resistance and were confirmed to be excellent in heat resistance. In particular, Examples 3 to 5, 8 and 9 have a peel strength of the adhesive sheet to glass at 120 ° C. higher than that of the other examples, and show extremely excellent heat resistance such that no foaming is observed even at 120 ° C. It was. The composition of the pressure-sensitive adhesive composition is that the acrylic pressure-sensitive adhesive polymer (B) has a Tg of −30 ° C. to 10 ° C., particularly in the range of −25 ° C. to 0 ° C. This is probably because the temperature was within the corresponding temperature range. Further, according to the pressure-sensitive adhesive compositions of Examples 3 to 5, 8 and 9, it was found that low tackiness was also exhibited, and both heat resistance and low tackiness were achieved. . Each of the acrylic adhesive polymers (B) used in these examples has (meth) acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms as a constituent monomer. It was thought that it contributed to these characteristics.

Also, from comparison between Example 4 and Example 8, it was found that a large number average molecular weight and / or weight average molecular weight of the acrylic pressure-sensitive adhesive polymer (B) contributed to the peel strength at high temperature.

On the other hand, in the pressure-sensitive adhesive compositions of Comparative Examples 1 to 3, the resulting pressure-sensitive adhesive sheets had insufficient heat resistance (foaming resistance). The comparative example 1 is based on the adhesive composition which does not contain a vinyl polymer (A). Comparative Example 2 The molecular weight of the vinyl polymer (A) is relatively high, and Comparative Example 3 is an example using a vinyl polymer (A) having a slightly low Tg, both having low peel strength at high temperature (100 ° C.). It is.

The pressure-sensitive adhesive composition of the present invention can be suitably used for various general pressure-sensitive processed products such as pressure-sensitive adhesive films, pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes and labels. In particular, it can be suitably used for these products requiring high heat resistance. Moreover, it can use for these products in which high heat resistance and low tack property are calculated | required. Specific examples of the adhesive processed product include an adhesive sheet, an adhesive film, an adhesive tape, a pressure sensitive tape, a surface protective film, a surface protective tape, a masking tape, an electrical insulating tape, and a laminate. In addition to the above, since the pressure-sensitive adhesive composition of the present invention is excellent in transparency and peeling strength and foaming resistance to various adherends under high temperature conditions, a touch panel, a liquid crystal display device, and an organic EL display device It is also suitable for bonding displays such as plasma display panels and various optical films used in these displays.

Claims

An adhesive composition comprising a vinyl polymer (A) and an acrylic adhesive polymer (B),
The first Tg, which is the glass transition temperature of the entire pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, is −80 ° C. or higher and 10 ° C. or lower.
The second Tg, which is the glass transition temperature calculated from the surface layer portion obtained by X-ray photoelectron spectroscopy of the pressure-sensitive adhesive layer, is 30 ° C. or more higher than the first Tg,
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a thickness of 50 μm formed from the pressure-sensitive adhesive composition on a 100 μm-thick polyethylene terephthalate film substrate, having a peel strength with respect to glass at 100 ° C. of 4.0 N / 25 mm or more. Agent composition.
2. The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive sheet has a peel strength with respect to glass at 120 ° C. of 0.5 N / 25 mm or more.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the vinyl polymer (A) has a glass transition temperature (Tg) of 60 ° C or higher and 200 ° C or lower.
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the vinyl polymer (A) has a number average molecular weight of 500 or more and 10,000 or less.
The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the second Tg is 40 ° C or higher.
The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the acrylic adhesive polymer (B) has a glass transition temperature of -30 ° C or higher and 10 ° C or lower.
The pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein the vinyl polymer (A) is contained in an amount of 0.5 to 60 parts by mass with respect to 100 parts by mass of the acrylic adhesive polymer (B). object.
The acrylic pressure-sensitive adhesive polymer (B) contains 10% by mass or more of a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms with respect to all the constituent monomers. Item 8. The pressure-sensitive adhesive composition according to any one of Items 1 to 7.
A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition according to any one of claims 1 to 8.