JP2021091768A - Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet - Google Patents

Abstract

To provide a pressure-sensitive adhesive sheet not only excellent in repeelability and stain resistance which are the required qualities necessary for a surface protection sheet for process conservation but also superior in adhesiveness and durability necessary for the sheet for product protection compared to the conventional sheet and enables compatibility for both process and product protection, and to provide the adhesive composition capable of forming the above adhesive sheet.SOLUTION: An objective pressure-sensitive adhesive composition includes an acrylic copolymer (A) and a hardener (B). The acrylic copolymer (A) is the copolymer of a monomer mixture including (a-1) to (a-4) mentioned below. (a-1): (meth)acrylic alkyl ester having 4-8C alkyl groups, (a-2): (meth)acrylic alkyl ester having hydroxyl groups, (a-3): (meth)acrylic alkyl ester having an alicyclic structure and (a-4): N-substituted (meth)acrylic amide. The copolymer (A) includes (a-3) of 10 mass% or more but less than 30 mass% and (a-4) of 5 mass% or more but less than 20 mass% in 100 mass% of the monomer mixture. The content of the hardener (B) is 0.1 pts.mass or more but 10 pts.mass or less based on 100 pts.mass of the acrylic copolymer (A).SELECTED DRAWING: None

Description

The present invention relates to a pressure-sensitive adhesive composition containing an acrylic copolymer and a pressure-sensitive adhesive sheet.

An adhesive sheet having an adhesive layer formed from an adhesive composition is easier to handle than an adhesive, and is therefore used in a wide range of fields such as display labels, fixing tapes, and surface protective sheets.
In recent years, smart devices and display devices such as car navigation systems that use an image display device such as a liquid crystal display or an organic EL display in combination with a touch panel have become widespread. Optical members such as polarizing plates, retardation plates, antireflection films, hard coat films, and transparent conductive films are used in these display devices in order to prevent damage to the optical members during manufacturing and transportation. , A surface protection sheet is attached for process protection.

The process protection surface protection sheet is peeled off from the optical member and removed after assembling each optical member. If the adhesive strength at the time of peeling is strong during the removal work, the optical member to be protected may be damaged. Therefore, re-peelability is required so that the optical member can be peeled even after being attached to the optical member for a long time. Further, the adhesive layer of the surface protection sheet for process protection needs to have stain resistance that does not adhere to and remain on the optical member to be protected.

Further, after the display device is manufactured, the display device is often visually inspected with the surface protection sheet attached, and the surface protection sheet is required to have high transparency.

Furthermore, the surface protection sheet is used for product protection in the cover panel and cover film formed on the top of the smart device in order to prevent the final product from being scratched or contaminated by sebum during use. The surface protection sheet for product protection is required to have adhesiveness so that the surface protection sheet does not float or peel off during transportation and use.

Further, in recent smart devices, in order to maintain high antifouling property, the outermost cover glass may be subjected to fingerprint resistance treatment such as superhydrophobic treatment. Since the superhydrophobicized cover glass has both oil-repellent and water-repellent properties, there is a problem that when a conventional surface protective sheet is used, it floats or peels off from the cover glass. In addition to the conventional performance, the surface protection sheet for product protection used in these smart devices requires higher adhesion to a difficult-to-adhere base material.

Furthermore, unlike fixed display devices such as TVs and PCs, smart devices and car navigation systems may be used in harsh environments such as high temperature and high temperature and high humidity atmospheres, so they are used as surface protection sheets for product protection. Requires high durability.

In this way, the re-peelability and stain resistance, which are the required qualities for process protection, and the adhesion and durability required for product protection are mutually exclusive performances, so they are for process protection and product protection. And, different surface protection sheets are used. However, this causes a problem that a defect occurs in the display device when the surface protective sheet is replaced, and the quality deteriorates. Further, since the surface protection sheet for process protection is discarded after use, there is a problem of cost increase due to the reattachment process.

Patent Document 1 describes a surface protective film containing an acrylic polymer, an antistatic agent, and a polyether-modified siloxane compound and having excellent removability. However, when this is used for product protection, it adheres. Insufficient properties and durability. Further, Patent Document 2 contains an acrylic polymer composed of a hydroxyl group-containing monomer, an alkylene glycol group-containing monomer, a nitrogen-containing monomer, and an alkoxy group-containing monomer, a cross-linking agent, and an antistatic agent, and is excellent in adhesion and durability. Although a surface protective film is described, when it is used for process protection, re-peelability and stain resistance are not sufficient.

Japanese Unexamined Patent Publication No. 2019-11479 Japanese Unexamined Patent Publication No. 2019-14902

In this way, in the manufacture of various optical members, the same adhesive sheet is used as the surface protection sheet for process protection and the surface protection sheet for product protection, which are required to have conflicting performances, and the surface protection sheet is attached in the process. At present, it is difficult to manufacture display devices without replacement.

The present invention has been made in view of the above circumstances, and is not only excellent in removability and stain resistance, which are the required qualities required for a surface protection sheet for process protection, but also necessary for a surface protection sheet for product protection. Adhesiveness and durability are also superior to the conventional ones, and a pressure-sensitive adhesive sheet capable of achieving both process protection and product protection, which was difficult with conventional pressure-sensitive adhesive sheets, and a pressure-sensitive adhesive composition capable of forming the pressure-sensitive adhesive sheet. The purpose is to provide goods.

As a result of diligent studies by the present inventor, it has been found that the problems of the present invention can be solved in the following aspects, and the present invention has been completed.
That is, the pressure-sensitive adhesive sheet according to the present invention contains an acrylic copolymer (A) and a curing agent (B).
The acrylic copolymer (A) is a copolymer of a monomer mixture containing the following (a-1) to (a-4), and 10 (a-3) is contained in 100% by mass of the monomer mixture. It contains 5% by mass or more and less than 20% by mass of (a-4) and 5% by mass or more and less than 20% by mass, and the content of the curing agent (B) is based on 100 parts by mass of the acrylic copolymer (A). The pressure-sensitive adhesive composition is 0.1 part by mass or more and 10 parts by mass or less.

(A-1) Alkyl ester of (meth) acrylic acid having an alkyl group having 4 to 8 carbon atoms (a-2) Alkyl ester of (meth) acrylic acid having a hydroxyl group (a-3) Having an alicyclic structure (meth) Acrylic acid alkyl ester (a-4) N-substituted (meth) acrylamide

According to the present invention, not only is the adhesive sheet excellent in removability and stain resistance, which is the required quality for the surface protection sheet for process protection, but also the adhesion and durability required for the surface protection sheet for product protection. It is possible to provide an excellent adhesive sheet.
As a result, the surface protection sheet using the adhesive sheet of the present invention can be used for process protection and product protection without replacement, so that the display device is damaged due to the replacement of the surface protection sheet, and the quality is deteriorated due to defects. Can be prevented.

Define terms used herein. The (meth) acrylic acid ester includes an acrylic acid ester and a methacrylic acid ester. The monomer is an ethylenically unsaturated group-containing monomer. Examples of the monomer constituting the acrylic copolymer (A) include (a-1) a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms, and (a-2) a (meth) acrylic having a hydroxyl group. It can be classified into acid alkyl esters, (a-3) (meth) acrylic acid alkyl esters having an alicyclic structure, (a-4) N-substituted (meth) acrylamides, and other monomers. The adherend is the other party to which the adhesive sheet is attached. Sheets, films and tapes are synonyms in the present invention.
Unless otherwise specified, the various components mentioned in the present specification may be used independently or in combination of two or more.

<< Adhesive composition >>
The pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer (A) and a curing agent (B).
The acrylic copolymer (A) is a copolymer of a monomer mixture containing the following (a-1) to (a-4), and 10 (a-3) is contained in 100% by mass of the monomer mixture. It contains 5% by mass or more and less than 20% by mass of (a-4) and 5% by mass or more and less than 20% by mass, and the content of the curing agent (B) is based on 100 parts by mass of the acrylic copolymer (A). The pressure-sensitive adhesive composition is 0.1 part by mass or more and 10 parts by mass or less.

(A-1) Alkyl ester of (meth) acrylic acid having an alkyl group having 4 to 8 carbon atoms (a-2) Alkyl ester of (meth) acrylic acid having a hydroxyl group (a-3) Having an alicyclic structure (meth) Acrylic acid alkyl ester (a-4) N-substituted (meth) acrylamide

<Acrylic copolymer (A)>
The acrylic copolymer (A) (hereinafter referred to as "copolymer (A)") in the present specification is a copolymer of a monomer mixture containing (a-1) to (a-4), and (A-3) is contained in an amount of 10% by mass or more and less than 30% by mass, and (a-4) is contained in an amount of 5% by mass or more and less than 20% by mass in 100% by mass of the monomer mixture.
As a result, the adhesive layer has a trade-off property of achieving both hardness and softness, so that removability, adhesion, and durability can be achieved at the same time.

The weight average molecular weight of the copolymer (A) is preferably 500,000 to 1.8 million, more preferably 800,000 to 1.5 million. When it is in the range of 500,000 to 1.8 million, the cohesive force is further improved, and the moisture resistance and heat resistance are further improved. The weight average molecular weight and the number average molecular weight are polystyrene-equivalent values measured by a gel permeation chromatography (GPC) method. Details of the GPC measurement method are described in Examples.

[(A-1) (Meta) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms]
(A-1) is a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms. The copolymer (A) contains (a-1) an (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms to impart sufficient wettability and cohesiveness to the adhesive layer. It is possible to improve the adhesion to the base material. When the number of carbon atoms of the alkyl group is less than 4, the flexibility of the adhesive layer is lowered and the adhesion to the base material is lowered. Further, when the number of carbon atoms exceeds 8, the rigidity of the adhesive layer is lowered and the durability is lowered.

The (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms (a-1) is, for example, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, (meth). Examples thereof include 2-ethylhexyl acrylate and isooctyl (meth) acrylate.
These can be used alone or in combination of two or more.
Of these, butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferable in terms of both flexibility and cohesiveness.

(A-1) The content of the (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms is preferably 40% by mass or more and 84% by mass or less, preferably 50% by mass, based on 100% by mass of the monomer mixture. % Or more and 80% by mass or less are more preferable. When the content is 40% by mass or more, sufficient cohesiveness can be easily obtained, and when the content is 84% by mass or less, cohesive force and adhesion can be easily achieved at a high level.

[(A-2) (meth) acrylic acid alkyl ester having a hydroxyl group]
(A-2) is a (meth) acrylic acid alkyl ester having a hydroxyl group. The copolymer (A) contains a (meth) acrylic acid alkyl ester having a (a-2) hydroxyl group, thereby forming a polymer network by a cross-linking reaction with the curing agent (B). As a result, in addition to improving the adhesion between the adhesive layer and the base material, removability, stain resistance, and durability are improved.

The (meth) acrylic acid alkyl ester monomer having a (a-2) hydroxyl group includes, for example, 2-hydroxyethyl (meth) acrylic acid, 2-hydroxypropyl (meth) acrylic acid, 3-hydroxypropyl (meth) acrylic acid, and the like. Examples thereof include 2-hydroxybutyl (meth) acrylic acid, (meth) acrylic acid, and 4-hydroxybutyl (meth) acrylic acid.
These can be used alone or in combination of two or more.
Of these, 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is more preferable in terms of improving durability.

(A-2) The content of the (meth) acrylic acid alkyl ester having a hydroxyl group is preferably 0.1% by mass or more and 5% by mass or less, and 0.2% by mass or more 2 in 100% by mass of the monomer mixture. More preferably, it is by mass or less. When the content is 0.1% by mass or more, sufficient cohesive force can be easily obtained, and when the content is 5% by mass or less, both cohesive force and adhesion can be easily achieved at a high level.

[(A-3) (meth) acrylic acid alkyl ester having an alicyclic structure]
(A-3) is a (meth) acrylic acid alkyl ester having an alicyclic structure. By containing the (a-3) (meth) acrylic acid alkyl ester having an alicyclic structure, the copolymer (A) can impart sufficient elasticity to the pressure-sensitive adhesive layer, and the heat resistance is improved. Further, since the polarity of the adhesive layer is lowered, the adhesion to the low-polarity adherend is improved.

The (meth) acrylic acid alkyl ester having an alicyclic structure (a-3) is, for example, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate, di (meth) acrylic acid. Cyclopentanyl, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate and the like can be mentioned.
These can be used alone or in combination of two or more.
Among them, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, or isobornyl (meth) acrylate are preferable from the viewpoint of durability in a high temperature atmosphere and adhesion to a low-polarity adherend.

(A-3) The content of the (meth) acrylic acid alkyl ester having an alicyclic structure is 10% by mass or more and less than 30% by mass, preferably 15% by mass or more and 27% by mass or less in 100% by mass of the monomer mixture. It is more preferably 15% by mass or more and 25% by mass or less. When the content is 10% by mass or more, the durability is excellent, and when the content is less than 30% by mass, the adhesion is good.

[(A-4) N-substituted (meth) acrylamide]
(A-4) is N-substituted (meth) acrylamide. When the copolymer (A) contains (a-4) N-substituted (meth) acrylamide, sufficient elasticity can be imparted to the adhesive layer, and the adhesive layer is excellent in moisture and heat resistance. Further, since the polarity of the adhesive layer is increased, the adhesion to the highly polar adherend is excellent.

(A-4) N-substituted (meth) acrylamide is, for example, N-methylacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminopropyl (meth) acrylamide. , Diacetone acrylamide, N- (butoxymethyl) acrylamide, and other (meth) acrylamide compounds;
Examples thereof include compounds containing a heterocycle such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine.
These can be used alone or in combination of two or more.
Of these, diacetone acrylamide, N-vinylpyrrolidone, and acryloylmorpholine are preferable from the viewpoint of durability in a high-temperature and high-humidity atmosphere and adhesion to a highly polar adherend.

The content of (a-4) N-substituted (meth) acrylamide is 5% by mass or more and less than 20% by mass, preferably 8% by mass or more and 18% by mass or less, more preferably, in 100% by mass of the monomer mixture. It is 8% by mass or more and 15% by mass or less. When the content is 5% by mass or more, the durability is improved, and when it is less than 20% by mass, the adhesion is excellent.

Details will be described later, but when a pressure-sensitive adhesive sheet composed of the copolymer (A) and the curing agent (B) is attached to a low-polarity adherend such as an olefin, the copolymer (A) is a low-polarity monomer. By containing the (meth) acrylic acid alkyl ester unit having the (a-3) alicyclic structure, the adhesion to the low-polarity adherend is excellent. Further, when affixed to a highly polar adherend such as glass or metal, the copolymer (A) is high because it contains a structural unit derived from (a-4) N-substituted (meth) acrylamide, which is a highly polar monomer. Adhesion to polar adherends is improved. As described above, by containing both the low-polarity and high-polarity monomer units in a specific content, the copolymer (A) dramatically improves the adhesion to both the low-polarity and high-polarity adherends. To do. Further, by containing the copolymer (A) in a specific ratio of the low-polarity monomer (a-3) and the high-polarity monomer (a-4), the characteristics of both low-polarity and high-polarity can be obtained. It also has excellent adhesion to difficult-to-adhere substrates such as super-water-repellent substrates.

[Other monomers]
The copolymer (A) has (a-1) a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms, (a-2) a (meth) acrylic acid alkyl ester having a hydroxyl group, and (a-). 3) In addition to the (meth) acrylic acid alkyl ester having an alicyclic structure and the (a-4) N-substituted (meth) acrylamide, other monomers can be used. Other monomers include (a-1) (meth) acrylic acid alkyl esters other than (meth) acrylic acid alkyl esters having an alkyl group having 4 to 8 carbon atoms, (meth) acrylic acid esters having a carboxyl group, and epoxy groups. Examples thereof include a (meth) acrylic acid ester having an amino group, a (meth) acrylic acid ester having an amino group, a (meth) acrylic acid ester having an alkyleneoxy group, and a vinyl monomer.

Examples of (meth) acrylic acid alkyl esters other than (meth) acrylic acid alkyl esters having an alkyl group having 4 to 8 carbon atoms include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, and (a-1). Examples thereof include propyl acrylate (meth), decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl (meth) acrylate.

The (meth) acrylic acid ester having a carboxyl group includes, for example, (meth) acrylic acid, acrylic acid p-carboxybenzyl, acrylic acid β-carboxyethyl, maleic acid, monoethylmaleic acid, itaconic acid, citraconic acid, fumaric acid. And so on.

Examples of the (meth) acrylic acid ester having an epoxy group include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and 6-methyl (meth) acrylate. -3,4-Epoxycyclohexylmethyl and the like can be mentioned.

The (meth) acrylic acid ester having an amino group is, for example, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylamino (meth) acrylate. Examples thereof include (meth) acrylic acid monoalkylamino esters such as propyl.

Examples of the (meth) acrylic acid ester having an alkyleneoxy group include a monomer represented by the following general formula (1) and a monomer represented by the general formula (2).

General formula (1)

General formula (2)

In the general formula (1) and the general formula (2), R ₁ and R ₂ are independent hydrogen atoms or methyl groups, and n and m are integers representing repeating units, and 1 ≦ n ≦ 25 and 1 ≦ m. ≦ 25, preferably 1 ≦ n ≦ 13, 1 ≦ m ≦ 5.

Commercially available products of the monomer represented by the general formula (1) include, for example, methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a hydrogen atom, n = 1), methoxydiethylene glycol acrylate (Osaka Organic). Manufactured by Chemical Industry Co., Ltd .: In the above formula (1), R ₁ is a hydrogen atom, n = 2), methoxytriethylene glycol acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd .: In the above formula (1), R ₁ is a hydrogen atom, n = = 3), methoxypolyethylene glycol # 400 acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a hydrogen atom, n = 9), methoxypolyethylene glycol # 600 acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: In the above formula (1), R ₁ is a hydrogen atom, n = 13), methoxypolyethylene glycol # 1000 acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a hydrogen atom, n = 23). Methoxydiethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a methyl group, n = 2), methoxytriethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a methyl group, n = 3), methoxytetraethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a methyl group, n = 4), methoxypolyethylene glycol # 400 methacrylate (Shin-Nakamura) Manufactured by Chemical Industry Co., Ltd .: In the above formula (1), R ₁ is a hydrogen atom, n = 9), methoxypolyethylene glycol # 600 methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: In the above formula (1), R ₁ is a hydrogen atom, n = 13), methoxypolyethylene glycol # 1000 methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (1), R ₁ is a hydrogen atom, n = 23).

Commercially available products of the monomer represented by the general formula (2) include, for example, methoxytripropylene glycol acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: in the above formula (2), R ₁ is a hydrogen atom, m = 3), methoxytripropylene glycol. Methacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd .: In the above formula (2), R ₁ is a methyl group, m = 3)

Examples of the vinyl monomer include vinyl acetate, vinyl crotonic acid, styrene, acrylonitrile, and the like.
Other monomers may be used alone or in combination of two or more.

The content of other monomers is preferably 50% by mass or more and 80% by mass or less in 100% by mass of the monomer mixture. When the content is 50% by weight or more, the adhesion is further improved. Further, when the content is 80% by weight or less, it is easy to achieve both cohesive force and adhesion.

[Manufacturing of acrylic copolymer (A)]
The copolymer (A) can be synthesized by polymerizing a monomer mixture. As the polymerization, known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization are possible, but solution polymerization is preferable. As the solvent used in the solution polymerization, for example, acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone and the like are preferable.
The polymerization temperature is preferably a boiling point reaction of 60 to 120 ° C. The polymerization time is preferably about 5 to 12 hours.

The polymerization initiator used for the polymerization is preferably a radical polymerization initiator. The radical polymerization initiator is generally a peroxide or an azo compound.
Peroxides include, for example, di-t-butyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-. Dialkyl peroxides such as di (t-butylperoxy) hexin-3;
Peroxy esters such as t-butylperoxybenzoate, t-butylperoxyacetate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane; cyclohexanone peroxide, 3,3,5-trimethylcyclohexanoneper Ketone peroxides such as oxides and methylcyclohexanone peroxides;
2,2-bis (4,5-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-) Butyl peroxy) cyclohexane, n-butyl-4,4-bis (t-butyl peroxy) barate, and other peroxyketals;
Hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide;
Diacyl peroxides such as benzoyl peroxide, decanoyyl peroxide, lauroyl peroxide, 2,4-dichlorobenzoyl peroxide;
Examples thereof include peroxydicarbonate such as bis (t-butylcyclohexyl) peroxydicarbonate.

The azo compound is, for example, 2,2'-azobisisobutyronitrile such as 2,2'-azobisisobutyronitrile (abbreviation: AIBN), 2,2'-azobis (2-methylbutyronitrile);
2,2'-azobisvaleronitrile such as 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile);
2,2'-azobispropionitrile such as 2,2'-azobis (2-hydroxymethylpropionitrile);
Examples thereof include 1,1'-azobis-1-alkanenitrile such as 1,1'-azobis (cyclohexane-1-carbonitrile).

The polymerization initiator may be used alone or in combination of two or more.

The polymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the monomer mixture.

<Curing agent (B)>
The curing agent (B) reacts with the hydroxyl group of the copolymer (A).
The pressure-sensitive adhesive composition of the present invention preferably contains the curing agent (B) in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A), and is 0.5 to 8 parts by mass. It is more preferable to include parts by mass. When the content is 0.1 part by mass or more, the cohesive force is further improved, and when it is 10 parts by mass or less, it is preferable because both the cohesive force and the flexibility are easily achieved, and the durability and the stain resistance are also excellent. can do.

Examples of the curing agent (B) include isocyanate compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, and metal chelates.
These can be used alone or in combination of two or more.
Among them, the isocyanate compound is preferable because it can achieve both high cohesive force and adhesiveness, thereby improving durability and stain resistance.

The isocyanate compound is an isocyanate having two or more isocyanate groups. As the isocyanate compound, for example, isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates, and bullets, nurates, and adducts thereof are preferable.

Aromatic polyisocyanates include, for example, 1,3-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6- Tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4', 4 "-Triphenylmethane triisocyanate and the like can be mentioned.

Aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, and 1,3-butylene diisocyanate. Dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like can be mentioned.

The aromatic aliphatic polyisocyanate is, for example, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diethylbenzene, Examples thereof include 1,4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

The alicyclic polyisocyanate is, for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4. -Cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatemethyl) cyclohexane and the like can be mentioned.

The burette body is a self-condensate having a burette bond in which an isocyanate monomer is self-condensed. Examples of the burette body include a burette body of hexamethylene diisocyanate.

The nurate form is a trimer of an isocyanate monomer. For example, a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate, and the like can be mentioned.

The adduct is a bifunctional or higher functional isocyanate compound obtained by reacting an isocyanate monomer with a bifunctional or higher low molecular weight active hydrogen-containing compound. The adduct is, for example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane with trimethylene isocyanate, a compound obtained by reacting trimethylolpropane with xylylene diisocyanate, and trimethylol. Examples thereof include a compound obtained by reacting propane with isophorone diisocyanate, a compound obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate, and the like.

The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct-form or a nurate-form, which is a reaction product of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. The isocyanate compounds are hexamethylene diisocyanate trimetylolpropane adduct, hexamethylene diisocyanate nurate, tolylene diisocyanate trimethylolpropane adduct, tolylene diisocyanate nurate, isophorone diisocyanate trimetylolpropane adduct, and isophorone diisocyanate. A nurate form is preferable, and a trimethylolpropane adduct form of hexamethylene diisocyanate, a trimethylolpropane adduct form of tolylene diisocyanate, and a trimethylolpropane adduct form of isophorone diisocyanate are more preferable.

Epoxy compounds include, for example, glycerin diglycidyl ether, 1,6-hexanediol diglycidyl ether, N, N, N', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N'-. Diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl aminophenylmethane and the like can be mentioned.

Aziridine compounds include, for example, N, N'-diphenylmethane-4,4'-bis (1-aziridine carboxysite), tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, 4, Examples thereof include 4'-bis (ethyleneiminocarbonylamino) diphenylmethane.

The carbodiimide compound is preferably a high molecular weight polycarbodiimide produced by decarboxylating and condensing the diisocyanate compound in the presence of a carbodiimidization catalyst. The commercially available high molecular weight polycarbodiimide is preferably the carbodilite series manufactured by Nisshinbo. Among them, Carbodilite V-03, 07, 09 is preferable because it has excellent compatibility with an organic solvent.

The metal chelate is preferably a coordination compound of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium with acetylacetone or ethyl acetoacetate. Examples of the metal chelate include aluminum ethyl acetoacetate / diisopropyrate, aluminum trisacetylacetone, aluminum bisethylacetate / monoacetylacetone, and aluminum alkylacetate / diisopropyrate.

<Hydrogenated hydrocarbon resin (C)>
The pressure-sensitive adhesive composition of the present invention may contain a hydrogenated hydrocarbon resin (C) as long as the problem can be solved. By containing the hydrogenated hydrocarbon resin (C), elasticity can be imparted to the adhesive layer, and adhesion and heat resistance are further improved.

Examples of the hydrogenated hydrocarbon resin (C) include hydrogenated petroleum resin and hydrogenated terpene resin.
These can be used alone or in combination of two or more.

Examples of the hydrogenated petroleum resin include C5 hydrogenated petroleum resin, C9 hydrogenated petroleum resin, C5 / C9 hydrogenated petroleum resin, and styrene hydrogenated petroleum resin. The C5-based hydrogenated petroleum resin is obtained by adding a hydrogen atom to an unsaturated double bond of an aliphatic resin obtained by separating and purifying a C5 fraction obtained from petroleum naphtha. Further, the C9 hydrogenated petroleum resin is obtained by adding a hydrogen atom to an unsaturated double bond of an aromatic resin obtained by separating and purifying a C9 fraction obtained from petroleum naphtha. The C5 / C9 hydrogenated petroleum resin is obtained by adding a hydrogen atom to an unsaturated double bond of an aromatic aliphatic resin obtained by separating, mixing, copolymerizing and purifying a C5 fraction and a C9 fraction. .. The styrene-based hydrogenated petroleum resin is obtained by adding a hydrogen atom to an unsaturated double bond of a styrene resin obtained by separating, purifying, and polymerizing a styrene fraction obtained from petroleum naphtha.

Hydrogenated terpene resin is a general term for, for example, polyterpene resin, terpene phenol resin, aromatic terpene resin, and the like, and hydrogen atoms are added to unsaturated double bonds in these resins.

Examples of the C5 hydrogenated petroleum resin include East Tuck C100 and East Tuck C115W (manufactured by Eastman Chemical Company). The C9 hydrogenated petroleum resin is, for example, Archon P-90, Archon P-100, Archon P-125, Archon P-140, Archon M-90, Archon M-115, Archon M-135 (manufactured by Arakawa Chemical Industries, Ltd.). ) Etc. can be mentioned. Examples of the C5 / C9 hydrogenated petroleum resin include Imarb S-100, Imarb S-110, Imarb P-100, and Imarb P-140 (manufactured by Idemitsu Kosan Co., Ltd.). Examples of the styrene-based hydrogenated petroleum resin include FTR6100, FTR6110, FTR6125, FTR7080, FTR7100, and FTR7125 (manufactured by Mitsui Chemicals, Inc.). Examples of the hydrogenated terpene resin include Clearon P-105, Clearon P-125, Clearon M-105, Clearon P-115, and YS Polystar TH130 (manufactured by Yasuhara Chemical Co., Ltd.).

Among these hydrogenated hydrocarbon resins (C), C9-based hydrogenated petroleum resin, styrene-based hydrogenated petroleum resin, and hydrogenated terpene resin having a cyclic hydrocarbon structure are preferable because they can have excellent durability.
As the hydrogenated hydrocarbon resin (C), Archon M-90 is preferable for the C9 hydrogenated petroleum resin, FTR6100 is preferable for the styrene hydrogenated petroleum resin, and YS Polystar TH130 is preferable for the hydrogenated terpene resin.

The hydrogenated hydrocarbon resin (C) preferably contains 5 to 50 parts by mass, and more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the copolymer (A). When the content is 5 parts by mass or more, the heat resistance and adhesion are further improved, and when the content is 50 parts by mass or less, the adhesive performance is more excellent.

<Organic silane compound>
The pressure-sensitive adhesive composition of the present invention may further contain an organic silane compound.

Organic silane compounds include, for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltripropoxysilane, 3- (meth) acryloxi. An alkoxysilane compound having a (meth) acryloxy group, such as propyltributoxysilane, 3- (meth) acryloxipropylmethyldimethoxysilane, 3- (meth) acryloxipropylmethyldiethoxysilane;
An alkoxysilane compound having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane;
3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl)- 3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) An alkoxysilane compound having an amino group such as -3-aminopropylmethyldiethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane;
Alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, An alkoxysilane compound having an epoxy group such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-Chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-Triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyl Examples thereof include triethoxysilane, hexamethyldisilazane, and silicone resins having an alkoxysilyl group in the molecule.

The content of the organic silane compound is preferably 0.01 part by mass or more and 2 parts by mass or less, and preferably 0.05 part by mass or more and 1 part by mass or less with respect to 100 parts by mass of the copolymer (A). More preferred.

The pressure-sensitive adhesive composition of the present invention is filled with various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather-resistant stabilizers, plasticizers, and fillers as optional components as long as the problems can be solved. It can contain agents, anti-aging agents, anti-static agents and the like.

The pressure-sensitive adhesive composition of the present invention is suitable as a pressure-sensitive adhesive sheet, as a raw material for various plastic sheets, general labels / seals, pressure-sensitive adhesives, pressure-sensitive adhesives for laminated structures, and sealing agents, and as various resin additives. It can also be used very usefully as a raw material for and the like.

《Adhesive sheet》
The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition. Above all, it is preferable to provide a base material and a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive sheet is produced, for example, by applying a pressure-sensitive adhesive composition to a base material and drying it to form a pressure-sensitive adhesive layer. Further, the pressure-sensitive adhesive composition is applied to a peelable sheet and dried to form an pressure-sensitive adhesive layer, and the base materials are bonded to each other. Further, on the surface of the adhesive layer that is not in contact with the base material, a peelable sheet is usually attached until just before use to prevent foreign matter from adhering. The drying temperature is usually about 60 to 150 ° C. The thickness of the adhesive layer is usually about 0.1 to 200 μm.

Examples of the coating method include known methods such as a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.

When applying the pressure-sensitive adhesive composition, the viscosity can be adjusted with a solvent. The solvent is, for example, a hydrocarbon solvent such as toluene, xylene, hexane, heptane; an ester solvent such as ethyl acetate or butyl acetate; a ketone solvent such as acetone or methyl ethyl ketone; a halogenated hydrocarbon solvent such as dichloromethane or chloroform. ; Examples include ether solvents such as diethyl ether, methoxytoluene, and dioxane.

As the base material, a flexible sheet and a plate material can be used without limitation. Examples of the base material include films, plastics, papers, metal foils, and laminates thereof.
In order to improve the adhesion to the surface of the base material in contact with the adhesive layer, easy adhesion treatment such as dry treatment such as corona discharge treatment or wet treatment such as coating of an anchor coating agent can be performed in advance.
As the base material, a laminated body obtained by laminating a single base material or a plurality of base materials can be used.
When the pressure-sensitive adhesive sheet of the present invention is used as an optical pressure-sensitive adhesive sheet having a base material, it is preferable to use a transparent and light-transmitting film as the base material.
The thickness of the base material is usually about 10 to 250 μm.

As the release sheet, a known release sheet in which a known release treatment such as a silicone-based release agent is applied to the surface of plastic or paper can be used.
The thickness of the peelable sheet is usually about 10 to 250 μm.

The adherend can be used without any particular restrictions. The adherend is general-purpose glass, building materials, polyolefins, ABS, polystyrene, acrylics and other plastics, cardboard, wood, plywood, stainless steel, aluminum and other metals, and for example, non-alkali glass, which is optical glass, polarizing plates, and elliptically polarized light. Examples thereof include optical members such as films, transparent conductive films, retardation films, antireflection films, brightness improving films, and super water repellent glass.
The pressure-sensitive adhesive sheet of the present invention can be suitably used as an optical pressure-sensitive adhesive sheet used for an optical member as an adherend.

<Optical adhesive sheet>
Since the pressure-sensitive adhesive layer, which is a cured product of the pressure-sensitive adhesive composition of the present invention, has excellent transparency, it can be suitably used as an optical pressure-sensitive adhesive sheet.
The optical adhesive sheet is an adhesive sheet used by being attached to an optical member, and is suitable as a surface protective sheet for a display device or the like.

When the optical pressure-sensitive adhesive sheet has a base material, it is preferable that the optical pressure-sensitive adhesive sheet includes an optical film as the base material and a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition.
The optical pressure-sensitive adhesive sheet is produced, for example, by applying a pressure-sensitive adhesive composition to an optical film and drying it to form a pressure-sensitive adhesive layer. Further, a pressure-sensitive adhesive composition is applied to a peelable sheet and dried to form a pressure-sensitive adhesive layer, and an optical film is bonded to the peelable sheet. Further, on the surface of the adhesive layer that is not in contact with the optical film, a peelable sheet is usually attached until just before use to prevent foreign matter from adhering. The drying temperature is usually about 60 to 150 ° C. The thickness of the adhesive layer is usually about 0.1 to 200 μm.

The optical film is a transparent and light-transmitting film, for example, polyvinyl alcohol, triacetyl cellulose, polyolefin (polypropylene, polyethylene), polycycloolefin, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene. Polyester resin such as naphthalate, polyacrylic resin such as polymethylmethacrylate and polybutylmethacrylate, polycarbonate resin, polynorbornene resin, polyarylate resin, polyacrylic resin, polyphenylene sulfide resin, polystyrene resin, polyamide resin, polyimide resin, Examples include epoxy resins.

Optical members include optical glass, polarizing plates, elliptically polarized films, transparent conductive films and low-polarity members, retardation films, antireflection films, brightness-enhancing films, and high-polarity (oil-repellent) and low-polarity (water-repellent). Examples thereof include super-water-repellent treated glass, which is a poorly adhesive base material having both characteristics.
The pressure-sensitive adhesive composition of the present invention has high adhesive strength and has excellent adhesion to superhydrophobic treated glass, which is a poorly adhesive base material.

Here, the superhydrophobic treated glass, which is a poorly adhesive base material, is a surface-treated glass in which a hydrophobic substance such as fluorine or silicon is coated or vapor-deposited on the glass surface, and then fine irregularities of 10 to 500 nm are formed on the surface. It is a material that has both oil repellency and water repellency. As a result, surface contamination due to moisture, sweat, and sebum can be highly prevented.

The use of the optical adhesive sheet of the present invention is not particularly limited, but for example, the surface of various electronics-related members such as liquid crystal displays, organic EL displays, plasma displays, touch screen panels, car navigation systems, in-vehicle interior display devices, and electrode peripheral members. It can also be used as a protective sheet.

In addition, in recent smart devices and in-vehicle interior display device protection sheets such as car navigation systems, floating or peeling from the display device in a harsh environment such as a high temperature and high temperature and high humidity atmosphere, which has not been required in the past. Durability is required to suppress.

As described above, the copolymer (A) constituting the pressure-sensitive adhesive composition of the present invention can be applied to both the low-polarity member and the high-polarity member by containing both the low-polarity and high-polarity monomer units in a specific content. Adhesion is dramatically improved. Further, the adhesion to the superhydrophobic glass having both oil-repellent and water-repellent properties is improved, and it can be applied as a superhydrophobic glass protective sheet. Furthermore, since it has high durability in a high temperature and high temperature and high humidity atmosphere, which has not been required in the past, it can be applied for protection of smart devices and in-vehicle interior display devices.

Next, examples will be given and further details will be described, but the present invention is not limited thereto. In the example, unless otherwise specified, "parts" means "parts by mass", "%" means mass%, and "RH" means relative humidity.
In addition, the compounding amount in the table is a mass part. The blanks in the table indicate that they are not mixed.
The method for measuring the weight average molecular weight and viscosity of the copolymer is as follows.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was measured by using a GPC "LC-GPC system" manufactured by Shimadzu Corporation. The weight average molecular weight (Mw) was determined in terms of polystyrene having a known molecular weight as a standard substance.
Device name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: 4 GMHXL manufactured by Tosoh Co., Ltd. and 1 HXL-H manufactured by Tosoh Co., Ltd. were connected.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml / min Column temperature: 40 ° C

<Measurement of viscosity>
The viscosity was measured using a Brookfield viscometer under the condition of a temperature of 25 ° C. and a relative humidity of 55%.
Device name: HADV-E (manufactured by Brookfield)
Spindle used: HANo. 7
Rotation speed: 50 rpm

The materials used in the examples are shown below.
"material"
<Monomer>
[(A-1) (Meta) acrylic acid alkyl ester having an alkyl group having 4 to 8 carbon atoms]
EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate [(meth) acrylic acid alkyl ester having (a-2) hydroxyl group]
HEA: 2-Hydroxyethyl acrylate HBA: 4-Hydroxybutyl acrylate [(a-3) (meth) acrylic acid alkyl ester having an alicyclic structure]
CHA: Cyclohexyl acrylate IBXA: Isobornyl acrylate DCPA: Dicyclopentanyl acrylate [(a-4) N-substituted (meth) acrylamide]
DAAM: Diacetone Acrylamide ACMO: Acryloyl Morpholine NVP: N-Vinylpyrrolidone [Other Monomers]
MA: Methyl acrylate <hardener (B)>
B-1: Trimethylolpropane adduct of tolylene diisocyanate B-2: Trimethylolpropane adduct of hexamethylene diisocyanate B-3: Nurate of hexamethylene diisocyanate B-4: N, N, N', N'- Tetraglycidyl-m-xylylene diisamine B-5: N, N'-diphenylmethane-4,4'-bis (1-aziridine carboxite)
<Hydrogenated hydrocarbon resin (C)>
C-1: Archon M-90 (C9 hydrogenated petroleum resin)
C-2: FTR6100 (styrene-based hydrogenated petroleum resin)
C-3: YS Polystar TH130 (hydrogenated terpene resin)

<Acrylic copolymer (A)>
[Synthesis Example 1: Copolymer (A-1)]
79.0 parts of 2-ethylhexyl acrylate (EHA), acrylic in a reaction vessel (hereinafter simply referred to as "reaction vessel") equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. 2-Hydroxyethyl acid (HEA) 1.0 part, cyclohexyl acrylate (CHA) 10.0 parts, diacetone acrylamide (DAAM) 10.0 parts, ethyl acetate 100 parts, 2,2'-azobisisobutyro 0.2 part of nitrile (hereinafter referred to as AIBN) was charged, and the atmosphere in the reaction vessel was replaced with nitrogen gas. Then, the reaction was started by heating to 65 ° C. while stirring in a nitrogen atmosphere. Then, the reaction solution was reacted at 65 ° C. for 4 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer (A-1) solution having a non-volatile content of 30% and a viscosity of 3000 mPa · s. The weight average molecular weight of the obtained copolymer (A-1) was 1.2 million.

[Synthesis Examples 2-16: Copolymers (A-2-10, AC-1-6)]
The copolymer (A) was synthesized by the same method as in Synthesis Example 1 except that the raw materials and the amounts used were changed according to the mass ratio in Table 1. The weight average molecular weight (Mw) of the obtained copolymer (A) is shown in Table 3.

(Example 1)
<Preparation of adhesive composition>
Aductate (B-1) of trimethylolpropane of tolylene diisocyanate as a curing agent (B) with respect to 100 parts of the copolymer (A-1) in the obtained copolymer (A-1) solution 1 Ethyl acetate was blended in 0.0 part so that the non-volatile content was 20%, and the mixture was stirred to obtain a pressure-sensitive adhesive composition.

<Making an adhesive sheet>
The obtained pressure-sensitive adhesive composition is placed on a release layer of a releaseable sheet (polyethylene terephthalate (PET), "E7004", silicone-based release layer, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm, and the thickness after drying becomes 10 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer. Next, a release layer surface of a releaseable sheet (polyethylene terephthalate, "SP-PET3811", silicone-based release layer, manufactured by Lintec Corporation) having a thickness of 38 μm is bonded to this adhesive layer, and a "release sheet / adhesive layer / release sheet" is attached. Was produced. Next, the obtained laminate was aged for 1 week under the condition of a temperature of 25 ° C. and a relative humidity of 55% to obtain an adhesive sheet.

(Examples 2 to 10, 16, 17, Comparative Examples 1 to 6, 9, 10)
As shown in Table 2, a pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the type of copolymer, the type of curing agent, and the blending amount (parts by mass) were changed.

(Example 11)
<Preparation of adhesive composition>
Alcon M-90, which is a C9-based hydrogenated petroleum resin, is used as the hydrogenated hydrocarbon resin (C) with respect to 100 parts of the copolymer (A-5) in the obtained copolymer (A-5) solution. 20 parts of (C-1) and 2.0 parts of the adduct body (B-1) of trimethyl propane of tolylene diisocyanate as a curing agent (B) are mixed with ethyl acetate so that the non-volatile content is 20% and stirred. To obtain a pressure-sensitive adhesive composition.

<Making an adhesive sheet>
The obtained pressure-sensitive adhesive composition is placed on a release layer of a releaseable sheet (polyethylene terephthalate (PET), "E7004", silicone-based release layer, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm, and the thickness after drying becomes 10 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer. Next, a release layer surface of a releaseable sheet (polyethylene terephthalate, "SP-PET3811", silicone-based release layer, manufactured by Lintec Corporation) having a thickness of 38 μm is bonded to this adhesive layer, and a "release sheet / adhesive layer / release sheet" is attached. Was produced. Next, the obtained laminate was aged for 1 week under the condition of a temperature of 25 ° C. and a relative humidity of 55% to obtain an adhesive sheet.

(Examples 12 to 15, Comparative Examples 7 and 8)
As shown in Table 2, an adhesive sheet was obtained in the same manner as in Example 11 except that the type of copolymer, the type of curing agent, the type of hydrogenated hydrocarbon resin, and the blending amount (parts by mass) were changed. ..

Using the obtained adhesive sheet, test laminates [A], [B], and [C] were prepared, and the following transparency, removability, stain resistance, adhesion, and durability were evaluated.

<< Preparation of test laminate >>
[Test laminate [A]; PET film / adhesive layer / non-alkali glass]
The obtained pressure-sensitive adhesive sheet was cut into a size of 25 mm in width and 100 mm in length to prepare a test pressure-sensitive adhesive sheet [A] composed of a PET film / adhesive layer / peelable sheet.
The peelable sheet of the test adhesive sheet [A] is peeled off, and the exposed adhesive layer is attached to a non-alkali glass plate (EN-A1: manufactured by Asahi Glass Co., Ltd.) at 25 ° C. and a relative humidity of 50% RH atmosphere using a laminator. , A test laminate [A] composed of a PET film / adhesive layer / glass was obtained.

[Test laminate [B]; PET film / adhesive layer / superhydrophobic glass]
The obtained adhesive sheet was cut out to a size of 66 mm in width × 145 mm in length (corresponding to a 6.1-inch display) to prepare a test adhesive sheet [B] composed of a PET film / adhesive layer / peelable sheet.
The peelable sheet of the test adhesive sheet [B] is peeled off, and the exposed adhesive layer is attached to superhydrophobic glass (Simplism) at 25 ° C. and a relative humidity of 50% RH atmosphere using a laminator, and the PET film / adhesive layer is attached. / A test laminate [B] made of superhydrophobic glass was obtained.

[Test laminate [C]; PET film / adhesive layer / smartphone]
The obtained adhesive sheet was cut out to a size of 66 mm in width × 145 mm in length (corresponding to a 6.1-inch display) to prepare a test adhesive sheet [C] composed of a PET film / adhesive layer / peelable sheet.
The peelable sheet is peeled off from the test adhesive sheet [C], and the exposed adhesive layer is attached to the superhydrophobic glass surface of a smartphone (Galaxy10: manufactured by Samsung) in an RH atmosphere at 25 ° C. and a relative humidity of 50% using a laminator. Then, a test laminate [C] composed of a PET film / adhesive layer / smartphone (the surface to which the adhesive layer was attached was superhydrophobic glass) was obtained.

"Evaluation method"
<Transparency>
The test laminate [A] was left at 23 ° C. and a relative humidity of 50% for 1 week, and then HAZE was measured. HAZE was measured using a Turbodimeter NDH5000W manufactured by Nippon Denshoku Kogyo Co., Ltd. The evaluation criteria are as follows.

◯: HAZE is less than 1.0 (good).
X: HAZE is 1.0 or more (defective).

<Removability>
A 180 ° peel test was carried out in which the test laminate [A] was left at 23 ° C. and a relative humidity of 50% for 1 week, and then peeled off at a speed of 300 mm / min in the 180 ° direction. The peel strength at the time of peeling was measured, and the re-peeling property was evaluated in two stages.

◯: "The peel strength is less than 2N, and there is no problem in practical use."
X: "Peeling strength is 2N or more, not practical"

<Stain resistance>
A 180 ° peel test was carried out in which the test laminate [A] was left at 23 ° C. and a relative humidity of 50% for 1 week, and then peeled off at a speed of 300 mm / min in the 180 ° direction. The fogging of the glass surface after peeling was visually observed, and the re-peeling property and the contaminating property were evaluated on a three-point scale.

◎: "There is no fogging on the glass surface, there is no problem in practical use"
◯: “Slight cloudiness is observed on the glass surface, but there is no problem in practical use”
X: "Cloudy on the glass surface or adhesion of the adhesive layer was observed, not practical"

<Adhesion (super water repellent glass)>
The test laminate [B] was left to stand for 500 hours under the condition of 40 ° C. as a heat-resistant adhesion test, cooled in an atmosphere of 25 ° C. and a relative humidity of 50%, and then bubbles were generated and the adhesive sheet was lifted or peeled off. Visual evaluation was performed under the following conditions (test condition [2]). Further, as an evaluation of the moisture resistance heat adhesion test, the test laminate [B] was left to stand in an atmosphere of 40 ° C. and a relative humidity of 90% for 500 hours, cooled in an atmosphere of 25 ° C. and a relative humidity of 50%, and then bubbles were generated. The floating and peeling of the adhesive sheet were visually evaluated under the following conditions (test condition [3]).
The heat adhesion (test condition [2]) and the moisture heat adhesion (test condition [3]) were evaluated based on the following three-stage evaluation criteria.

◎: "No bubbles are generated, no floating or peeling is observed, and there is no problem in practical use."
○: "There are slight bubbles, floating and peeling, but there is no problem in practical use."
Δ: "Practical use is not possible due to remarkable generation of bubbles, floating and peeling."

<Adhesion (smartphone)>
The test laminate [C] was left to stand for 500 hours under the condition of 40 ° C. as a heat-resistant adhesion test, cooled in an atmosphere of 25 ° C. and a relative humidity of 50%, and then bubbles were generated and the adhesive sheet was lifted or peeled off. Visual evaluation was performed under the following conditions (test condition [2]). Further, as an evaluation of the moisture resistance heat adhesion test, the test laminate [C] was left to stand in an atmosphere of 40 ° C. and a relative humidity of 90% for 500 hours, cooled in an atmosphere of 25 ° C. and a relative humidity of 50%, and then bubbles were generated. The floating and peeling of the adhesive sheet were visually evaluated under the following conditions (test condition [3]).
The heat adhesion (test condition [2]) and the moisture heat adhesion (test condition [3]) were evaluated based on the following three-stage evaluation criteria.

◎: "No bubbles are generated, no floating or peeling is observed, and there is no problem in practical use."
○: "There are slight bubbles, floating and peeling, but there is no problem in practical use."
Δ: "Practical use is not possible due to remarkable generation of bubbles, floating and peeling."

<Heat resistance / moisture heat resistance (non-alkali glass)>
The test laminate [A] was left to stand for 500 hours under the condition of 105 ° C. as a heat resistance test, cooled in an atmosphere of 25 ° C. and a relative humidity of 50%, and then bubbles were generated and the adhesive sheet was lifted or peeled off as follows. Visual evaluation was performed under the conditions of (heat resistance). Further, as an evaluation of the moisture resistance test, the above-mentioned test laminate was left to stand in an atmosphere of 85 ° C. and a relative humidity of 85% for 500 hours, cooled in an atmosphere of 25 ° C. and a relative humidity of 50% RH, and then bubbles were generated and an adhesive sheet was used. The floating and peeling of the material was visually evaluated under the following conditions (moisture and heat resistance).
The heat-resistant adhesion and the moisture-heat adhesion were evaluated based on the following three-stage evaluation criteria.

◎: "No bubbles are generated, no floating or peeling is observed, and there is no problem in practical use."
○: "There are slight bubbles, floating and peeling, but there is no problem in practical use."
Δ: "Practical use is not possible due to remarkable generation of bubbles, floating and peeling."

From the results in Table 3, the pressure-sensitive adhesive composition of Examples is excellent in transparency, removability, stain resistance, adhesion, and durability. That is, it is possible to provide a surface protection sheet that can be applied to both process protection and product protection. In addition, since it is not necessary to replace the surface protection sheet, it is possible to prevent damage to the display device due to replacement of the surface protection sheet and quality deterioration due to defects, and it is possible to maintain the quality of the display device and reduce costs by shortening the process. It was confirmed that.
On the other hand, the pressure-sensitive adhesive composition of the comparative example could not satisfy all of the above characteristics.

Claims (5)

Contains an acrylic copolymer (A) and a curing agent (B),
The acrylic copolymer (A) is a copolymer of a monomer mixture containing the following (a-1) to (a-4), and 10 (a-3) is contained in 100% by mass of the monomer mixture. Containing 5% by mass or more and less than 20% by mass and (a-4) by 5% by mass or more and less than 20% by mass
A pressure-sensitive adhesive composition in which the content of the curing agent (B) is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer (A).

(A-1) Alkyl ester of (meth) acrylic acid having an alkyl group having 4 to 8 carbon atoms (a-2) Alkyl ester of (meth) acrylic acid having a hydroxyl group (a-3) Having an alicyclic structure (meth) Acrylic acid alkyl ester (a-4) N-substituted (meth) acrylamide The pressure-sensitive adhesive composition according to claim 1, wherein the curing agent (B) is an isocyanate curing agent. The pressure-sensitive adhesive composition according to claim 1 or 2, further comprising a hydrogenated hydrocarbon resin (C). A pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 3. An optical pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer which is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 3.