TW202106836A - Composition for pressure-sensitive adhesive, pressure-sensitive adhesive film, and surface-protective film - Google Patents

Abstract

An embodiment of the present invention relates to a composition for pressure-sensitive adhesives which comprises a (meth)acrylic polymer (A), an alkali metal salt (B), and a compound (C) represented by formula (I).

Description

Adhesive composition, adhesive film, and surface protection film

The embodiment of the present invention relates to a composition for an adhesive, an adhesive film, and a surface protection film.

Optical films such as polarizing plates are used in displays. The surface of the optical film may be laminated with a surface protection film. The surface protection film protects the surface of the optical film and prevents damage and dirt adhesion during transportation and display manufacturing steps.

Generally, a surface protection film is provided with a base film and an adhesive film so that the surface protection film does not separate from the optical film, and the adhesive film is formed on one side of the base film. Sometimes the appearance inspection of the optical film is performed with the surface protection film attached to the optical film. Therefore, acrylic adhesives with high transparency are widely used in the adhesive film. In addition, when the surface protection film is not needed, it can be peeled and removed from the optical film. When peeling and removing the surface protective film, in order to be able to peel off easily, usually a micro-adhesive adhesive is used in the adhesive film.

When peeling and removing the surface protective film, especially when peeling at a high speed, the following phenomenon may sometimes occur: noise is generated. In addition, when peeling and removing, the following phenomena may occur due to the generated peeling static electricity: a phenomenon in which dust adheres to the surface of the optical film, a phenomenon in which circuit parts are destroyed, and the like. In order to improve productivity, the peeling speed of the surface protection film tends to be faster. If the peeling speed becomes faster, the peeling electrostatic voltage also becomes higher, and it becomes easy to cause defects caused by these phenomena.

In addition, in recent years, high-definition displays have progressed, and therefore, the requirements for the appearance of optical films have increased. Therefore, the following characteristics are required for the surface protection film: After peeling, the adhesive is not easy to remain on the optical film.

As an adhesive composition for forming a surface protective film, Citation 1 discloses an adhesive composition characterized by containing an ionic liquid and an acrylic polymer. In addition, Citation 2 discloses a surface protection film characterized by having an adhesive layer formed on the surface of the base film, and at least externally adding an antistatic agent and fluorine to the acrylic adhesive constituting the adhesive layer Or a compound of silicon. [Prior Technical Literature] (Patent Document)

Patent Document 1: Japanese Patent Application Publication No. 2005-330464 Patent Document 2: Japanese Patent Application Publication No. 2011-63712

[The problem to be solved by the invention]

An object of an embodiment of the present invention is to provide a composition for an adhesive, which can produce an adhesive film excellent in antistatic properties and low pollution. In addition, an object of another embodiment of the present invention is to provide an adhesive film which is excellent in antistatic properties and low pollution. Furthermore, an object of another embodiment of the present invention is to provide a surface protective film having an adhesive film excellent in antistatic properties and low pollution. [Technical means to solve the problem]

The present invention includes various embodiments. Examples of the embodiment are listed below. The present invention is not limited to the following embodiments.

式(I)中，X各自獨立地表示氧原子或氮原子，R各自獨立地表示氫原子、烷基、或氟烷基。One embodiment relates to a composition for an adhesive, which contains a (meth)acrylic polymer (A), an alkali metal salt (B), and a compound (C) represented by formula (1),

In formula (I), X each independently represents an oxygen atom or a nitrogen atom, and R each independently represents a hydrogen atom, an alkyl group, or a fluoroalkyl group.

In one embodiment, the composition for adhesives further contains a crosslinking agent (D).

In one embodiment, the (meth)acrylic polymer (A) preferably contains a structural unit derived from an alkyl (meth)acrylate monomer and (meth)acrylic acid derived from a hydroxyl group or a carboxyl group The structural unit of the monomer.

Another embodiment relates to an adhesive film obtained by using the aforementioned adhesive composition.

Another embodiment relates to a surface protection film having an adhesive film and a base film, and the adhesive film is obtained by using the aforementioned adhesive composition. [Effect of Invention]

According to an embodiment of the present invention, it is possible to provide a composition for an adhesive, which can produce an adhesive film excellent in antistatic properties and low pollution. Furthermore, according to another embodiment of the present invention, it is possible to provide an adhesive film which is excellent in antistatic properties and low pollution. Furthermore, according to another embodiment of the present invention, it is possible to provide a surface protection film having an adhesive film excellent in antistatic properties and low pollution.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.

<Composition for Adhesive> The adhesive composition of the embodiment of the present invention contains a (meth)acrylic polymer (A), an alkali metal salt (B), and a compound (C) represented by formula (1). The adhesive composition may further contain optional components such as a crosslinking agent (D) and various additives.

As a method of imparting antistatic properties to the surface protective film, there is a method of adding an antistatic agent to the adhesive film to be connected to the adherend. However, if the content of the antistatic agent is increased in order to improve the antistatic property, the amount of the antistatic agent attached to the adherend will also increase, so that the adherend is easily contaminated. Generally speaking, there is a trade-off relationship between antistatic properties and low pollution properties, and it tends to be difficult to balance them. In the embodiment of the present invention, by using a composition for an adhesive, it contains a (meth)acrylic polymer (A), an alkali metal salt (B), and a compound (C) represented by formula (1) , So as to achieve both excellent antistatic properties and low pollution.

[(Meth) acrylic polymer (A)] The (meth)acrylic polymer (A) is a polymer containing a structural unit derived from a (meth)acrylic monomer. The (meth)acrylic monomer has at least one (meth)acryloyl group in the molecule. In this specification, "(meth)acrylic monomer" is the general term of acrylic monomer and methacrylic monomer, and "(meth)acryloyl" refers to acryloyl and methacryloyl. Collectively.

The structural unit derived from a (meth)acrylic monomer preferably contains at least one structural unit derived from an alkyl (meth)acrylate monomer (M1). The structural unit derived from a (meth)acrylic monomer may contain 2 or more types of structural units derived from the alkyl (meth)acrylate monomer (M1).

The alkyl (meth)acrylate monomer (M1) preferably contains a monomer represented by the following formula (m1) (hereinafter, sometimes referred to as "monomer (m1)").

In the formula (m1), R ^1a represents a hydrogen atom or a methyl group, and R ^1b represents an alkyl group.

The alkyl group may be linear, branched, or cyclic. The alkyl group is preferably a linear alkyl group. The carbon number of the alkyl group is preferably 1-22, more preferably 1-16, and still more preferably 1-12.

The alkyl (meth)acrylate monomer (M1), for example, preferably contains at least one selected from the group consisting of: methyl (meth)acrylate, ethyl (meth)acrylate, Propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, Heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylic acid Isononyl ester, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate , Myristyl (meth)acrylate (myristyl (meth)acrylate), isomyristyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (Cetyl (meth)acrylate), isocetyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate (stearyl (meth)acrylate) , And isostearyl (meth)acrylate.

When the monomer used to form the structural unit of the (meth)acrylic polymer (A) contains the alkyl (meth)acrylate monomer (M1), the total amount of all monomers is 100 parts by mass as a reference. The content of the alkyl (meth)acrylate monomer (M1) is preferably 50 parts by mass or more, more preferably 55 parts by mass or more, and still more preferably 60 parts by mass or more. When the content is 50 parts by mass, there is a tendency that good adhesion between the adhesive film and the adherend is easily obtained. Considering the use of other monomers, the content of the alkyl (meth)acrylate monomer (M1) is preferably 99 parts by mass or less, more preferably 95 parts by mass based on the total amount of all monomers being 100 parts by mass. Parts by mass or less, more preferably 90 parts by mass or less.

The structural unit derived from a (meth)acrylic monomer preferably contains at least one structural unit derived from a (meth)acrylic monomer (M2) having a hydroxyl group or a carboxyl group. The (meth)acrylic monomer (M2) has at least a hydroxyl group, a carboxyl group, or both a hydroxyl group and a carboxyl group. The structural unit derived from a (meth)acrylic-type monomer may contain 2 or more types of structural units derived from a (meth)acrylic-type monomer (M2).

The structural unit of the (meth)acrylic monomer (M2) preferably contains at least one selected from the group consisting of: a monomer represented by the following formula (m2-1) (hereinafter, Sometimes referred to as "monomer (m2-1)"), a monomer represented by the following formula (m2-2) (hereinafter, sometimes referred to as "monomer (m2-2)"), and (methyl )acrylic acid. The (meth)acrylic monomer (M2) more preferably contains the monomer (m2-1).

In the formula (m2-1), R ^2a represents a hydrogen atom or a methyl group, and R ^2b represents a divalent linking group.

In the formula (m2-2), R ^3a represents a hydrogen atom or a methyl group, and R ^3b represents a divalent linking group.

In each monomer (m2-1) and monomer (m2-2), the divalent linking group, for example, preferably contains one or more groups selected from the group consisting of: alkylene Group, oxy group, and carbonyl group. The alkylene group may be linear, branched, or cyclic. The alkylene group is preferably a linear alkylene group. The carbon number of the alkylene group is preferably 1-22, more preferably 1-16, and still more preferably 1-12. The divalent linking group is more preferably an alkylene group, and still more preferably a linear alkylene group.

The (meth)acrylic monomer (M2), for example, preferably contains at least one selected from the group consisting of: 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid 4 -Hydroxyalkyl (meth)acrylates such as hydroxybutyl ester, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, etc.; N-hydroxy(meth)acrylamide, N- Hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, etc. containing hydroxyl (meth)acrylamide; 2-carboxyethyl (meth)acrylate, (meth) 5-Carboxypentyl acrylate, 2-(meth)propyleneoxyethylhexahydrophthalic acid, 2-(meth)propyleneoxypropylhexahydrophthalic acid, 2-(meth)propylene Acetyloxyethyl phthalic acid, 2-(meth)propenyloxyethyltetrahydrophthalic acid, 2-(meth)propenyloxypropyltetrahydrophthalic acid, 2-(methyl) ) Propylene oxypropyl phthalic acid, 2-(meth) propylene oxyethyl succinic acid, 2-(meth) propylene oxypropyl succinic acid, 2-(meth) propylene oxyethyl Carboxyl group-containing (meth)acrylates such as maleic acid, 2-(meth)acryloxypropyl maleic acid, and carboxypolycaprolactone mono(meth)acrylate; and (meth)acrylic acid. The (meth)acrylic monomer (M2), for example, more preferably contains at least one selected from the group consisting of hydroxyalkyl (meth)acrylate and (meth)acrylic acid, and still more preferably contains (Meth) hydroxyalkyl acrylate.

When the monomer for forming the structural unit of the (meth)acrylic polymer (A) contains the (meth)acrylic monomer (M2), the total amount of all the monomers is 100 parts by mass as a reference, The content of the (meth)acrylic monomer (M2) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 2 parts by mass or more, and particularly preferably 2.5 parts by mass or more. When the content is 0.1 parts by mass or more, sufficient adhesiveness tends to be easily obtained. Based on the total amount of all monomers being 100 parts by mass, the content of the (meth)acrylic monomer (M2) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 14 parts by mass Parts or less, particularly preferably 12 parts by mass or less. When the content is 20 parts by mass or less, it is easy to obtain the effect of preventing the contamination of the adherend.

The structural unit derived from a (meth)acrylic monomer may include at least one structural unit derived from another (meth)acrylic monomer (M3), the other (meth)acrylic monomer (M3) The structural unit of is different from the structural unit derived from the alkyl (meth)acrylate (M1) and the structural unit derived from the (meth)acrylic monomer (M2). The structural unit derived from a (meth)acrylic-type monomer may contain 2 or more types of structural units derived from a (meth)acrylic-type monomer (M3).

The (meth)acrylic monomer (M3), for example, is preferably (poly)oxyalkylene (meth)acrylic acid containing (poly)alkylene glycol monoalkyl ether mono(meth)acrylate, etc. Department of monomers. In this specification, "(poly)alkylene glycol" is the general term for "alkylene glycol" and "polyalkylene glycol", and "(poly)oxyalkylene" refers to "oxyalkylene" and "polyoxyalkylene". The general term for "alkyl".

When the monomer used to form the structural unit of the (meth)acrylic polymer (A) contains the (meth)acrylic monomer (M3), the total amount of all monomers is 100 parts by mass as a reference, The content of the (meth)acrylic monomer (M3) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more. Based on the total amount of all monomers being 100 parts by mass, the content of the (meth)acrylic monomer (M3) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass Servings or less.

The (meth)acrylic polymer (A) may contain another structural unit different from the structural unit derived from the (meth)acrylic polymer. Examples of other structural units include structural units derived from the following vinyl-containing monomers: vinyl ester-based monomers such as vinyl acetate; styrene-based monomers such as styrene and sodium styrene sulfonate; butadiene Olefin monomers such as olefins; halogen-containing monomers such as vinyl chloride and tetrafluoroethylene.

The (meth)acrylic polymer (A) preferably contains a structural unit derived from a (meth)acrylic monomer (M2), and more preferably contains a structural unit derived from an alkyl (meth)acrylate (M1) Structural unit and structural unit derived from (meth)acrylic monomer (M2).

The polymerization method of the (meth)acrylic polymer (A) is not particularly limited. As a polymerization method of the (meth)acrylic polymer (A), the following known polymerization methods can be used: solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, and the like.

As a polymerization initiator when polymerizing the (meth)acrylic polymer (A), a compound capable of generating radicals by heat can be used. Specifically, examples include organic peroxides such as benzyl peroxide and laurel peroxide; 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutane) Nitriles) and other azo compounds.

The glass transition temperature (Tg) of the (meth)acrylic polymer (A) is preferably 0°C or lower, more preferably -5°C or lower, and still more preferably -10°C or lower. The glass transition temperature of the (meth)acrylic polymer (A) is preferably -50°C or higher, more preferably -40°C or higher, and still more preferably -25°C or higher.

In this specification, the glass transition temperature (Tg) of the (meth)acrylic polymer (A) means a theoretically calculated value obtained from the following FOX formula. 1/Tg=W1/Tg1＋W2/Tg2＋･･･＋Wn/Tgn In the above formula, Tg is the glass transition temperature (°C) of the (meth)acrylic polymer (A), and W1, W2, ･･･, Wn are each based on the mass of all monomers. The mass fraction, Tg1, Tg2, ･･･, and Tgn are each the glass transition temperature of the homopolymer of each monomer. As the glass transition temperature of the homopolymer used for this calculation, literature values can be used. The glass transition temperature of various homopolymers has been recorded in, for example, Mitsubishi Rayon Co., Ltd.'s acrylic ester catalog (1997 edition), and New Polymer Library 7 ("Introduction to Synthetic Resins for Coatings", published by the Polymer Publishing Association, Three works by Beigang Association).

As a method of adjusting the glass transition temperature of the (meth)acrylic polymer (A), the following methods can be cited. For example, it is possible to lower the glass transition temperature by using alkyl (meth)acrylate with a larger carbon number. On the other hand, it is possible to increase the glass transition temperature by using alkyl (meth)acrylate with a small carbon number. Even by using methacrylate, the glass transition temperature tends to be higher.

The weight average molecular weight of the (meth)acrylic polymer (A) is preferably 50,000 or more, more preferably 80,000 or more, and still more preferably 100,000. The weight average molecular weight of the (meth)acrylic polymer (A) is preferably 800,000 or less, more preferably 700,000 or less, and still more preferably 600,000 or less. In this specification, the weight average molecular weight is a value obtained by conversion by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. Specifically, what is necessary is just to follow the measurement method described in an Example. When the weight average molecular weight is more than 50,000, there is a tendency to obtain an adhesive film with good adhesion. When the weight average molecular weight is 800,000 or less, it is easy to prevent the adhesive composition from becoming high viscosity.

The adhesive composition may contain only one (meth)acrylic polymer (A), or two or more (meth)acrylic polymers (A).

[Alkali metal salt (B)] The alkali metal salt (B) contains an alkali metal ion and a relative anion. It is considered that when the composition for the adhesive contains the alkali metal salt (B), conductivity can be imparted to the adhesive film and the adhesive film can exhibit good antistatic properties. The alkali metal salt (B) preferably contains at least one selected from the group consisting of lithium ion, sodium ion, and potassium ion as an alkali metal ion, and more preferably contains one selected from the group consisting of lithium ion and sodium ion At least one of the groups, and more preferably contains lithium ions. When lithium ions are contained, better antistatic properties can be obtained.

The relative anion, for example, preferably contains at least one selected from the group consisting of the following ions: chloride ion, perchlorate ion, hexafluorophosphate ion, hexafluoroarsenate ion, tetrafluoroborate ion, tetrafluoroborate ion Phenylboronic acid ion, trifluoromethanesulfonic acid ion, bis(trifluoromethanesulfonyl)imide ion, and bis(pentafluoroethanesulfonyl)imide ion.

As an example of the alkali metal salt (B), a salt represented by the following formula (hereinafter, the salt represented by the formula (b1) may be referred to as "salt (b1)". Regarding the formulas (b2) to (b6) The salt represented by any one of) is also the same).

In each formula, M represents an alkali metal ion, R represents a fluorine atom, an alkyl group, a fluoroalkyl group, an aryl group, or a fluoroaryl group, and R ¹ and R ² each independently represent a fluorine atom, an alkyl group, a fluoroalkyl group, and an aryl group.基, or fluoroaryl.

The number of carbon atoms in the alkyl group and the fluoroalkyl group is preferably from 1 to 6, and more preferably from 1 to 4. The fluoroalkyl group may be a fluoroalkyl group in which part of the hydrogen atoms contained in the alkyl group is replaced by fluorine atoms, or a fluoroalkyl group in which all hydrogen atoms are replaced by fluorine atoms (ie perfluoroalkyl group) , Preferably a perfluoroalkyl group. The carbon number of the aryl group and the fluoroaryl group is preferably 6-20, more preferably 6-10. The fluoroaryl group can be a fluoroaryl group in which part of the hydrogen atoms contained in the aryl group is replaced by fluorine atoms, or a fluoroaryl group in which all hydrogen atoms are replaced by fluorine atoms (that is, a perfluoroaryl group) , Preferably a perfluoroaryl group.

The alkali metal salt (B) preferably includes at least one selected from the group consisting of salt (b1) to salt (b6), and more preferably includes selected from salt (b1), salt (b5) and salt (b6) At least one of the group consisting of, and more preferably at least one selected from the group consisting of salt (b1) and salt (b5). In particular, the alkali metal salt (B) preferably contains the salt (b5) from the viewpoints of good compatibility with the (meth)acrylic polymer (A), no chlorine, and easy release of the alkali metal salt.

Specifically, the alkali metal salt (B) preferably contains at least one selected from the group consisting of: lithium chloride (LiCl), lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ) , Lithium hexafluoroarsenate (LiAsF ₆ ), Lithium tetrafluoroborate (LiBF ₄ ), Lithium tetraphenylborate (LiB(C ₆ H ₅ ) ₄ ), Lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), double (Trifluoromethanesulfonyl) lithium imide (LiN(CF ₃ SO ₂ ) ₂ ), bis(pentafluoroethanesulfonyl) lithium imide (LiN(C ₂ F ₅ SO ₂ ) ₂ ) and other lithium salts; chlorine Sodium chloride (NaCl), sodium perchlorate (NaClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), sodium hexafluoroarsenate (NaAsF ₆ ), sodium tetrafluoroborate (NaBF ₄ ), sodium tetraphenylborate (NaB (C ₆ H ₅ ) ₄ ), sodium trifluoromethanesulfonate (NaCF ₃ SO ₃ ), sodium bis(trifluoromethanesulfonate) imide (NaN(CF ₃ SO ₂ ) ₂ ), bis(pentafluoroethanesulfonate) Sodium salt of sodium imide (NaN(C ₂ F ₅ SO ₂ ) ₂ ), etc.; and, potassium chloride (KCl), potassium perchlorate (KClO ₄ ), potassium hexafluorophosphate (KPF ₆ ), hexafluoroarsenic Potassium acid (KAsF ₆ ), potassium tetrafluoroborate (KBF ₄ ), potassium tetraphenylborate (KB(C ₆ H ₅ ) ₄ ), potassium trifluoromethanesulfonate (KCF ₃ SO ₃ ), bis(trifluoromethane) Potassium salts of potassium sulfonamide (KN(CF ₃ SO ₂ ) ₂ ), potassium bis(pentafluoroethanesulfonyl) imide (KN(C ₂ F ₅ SO ₂ ) ₂ ) and the like.

The alkali metal salt (B) is preferably a salt having a melting point exceeding 25°C and being solid at room temperature (for example, 25°C). Since it is not easy to flow out from the adhesive film, from the viewpoint of preventing contamination of the adherend due to the adhesive film, a salt that is solid at room temperature is preferred.

The adhesive composition may contain only one kind of alkali metal salt (B), or may contain two or more kinds of alkali metal salt (B). Based on 100 parts by mass of the (meth)acrylic polymer (A) as a reference, the content of the alkali metal salt (B) is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and still more preferably 0.5 parts by mass Copies or more. When the content of the alkali metal salt (B) is 0.1 parts by mass or more, better antistatic properties can be obtained. Based on 100 parts by mass of the (meth)acrylic polymer (A) as a reference, the content of the alkali metal salt (B) is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 5 parts by mass Servings or less. When the content of the alkali metal salt (B) is 10 parts by mass or less, better low-contamination properties can be obtained.

[Compound (C) represented by formula (I)] The adhesive composition contains the compound (C) represented by the following formula (I). It is considered that in the adhesive film, the compound (C) can promote the movement of alkali metal ions contained in the alkali metal salt (B) and improve the antistatic property.

In formula (I), X each independently represents an oxygen atom or a nitrogen atom, and R each independently represents a hydrogen atom, an alkyl group, or a fluoroalkyl group. When X is an oxygen atom, -X- contained in formula (I) represents -O-. When it is a nitrogen atom, a hydrogen atom may be bonded to the nitrogen atom, and -X- contained in formula (I) can be represented by -NH-.

The alkyl group may be linear, branched, or cyclic. The alkyl group is preferably a group represented by -C _n H _{2n +1} (n is an integer of 1 or more). n is preferably 1-12, more preferably 1-8, and still more preferably 1-4.

The fluoroalkyl group may be linear, branched, or cyclic. Examples of the fluoroalkyl group include: a fluoroalkyl group in which part of the hydrogen atoms contained in the alkyl group are substituted by fluorine atoms, and a fluoroalkyl group in which all the hydrogen atoms contained in the alkyl group are substituted by fluorine atoms (that is, Perfluoroalkyl). The fluoroalkyl group is preferably a group represented by -C _n H _m F _{2n +1 -m} (n is an integer of 1 or more, m is an integer of 0 or more, and m is an integer of 2n or less). n is preferably 1-12, more preferably 1-8, and still more preferably 1-4. m is preferably 0 to 2n, more preferably 0 to n, and still more preferably 0.

From the viewpoint of improving the low pollution of the adhesive film, R in formula (I) is each independently a hydrogen atom, an alkyl group having 1 to 12 carbons, or a fluoroalkyl group having 1 to 12 carbons. The best compound.

Examples of the compound (C) include cyclic carbonate compounds and cyclic urea compounds. Specifically, the compound (C) preferably contains at least one selected from the group consisting of: ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, trans-2 ,3-butylene, cis-2,3-butylene carbonate, 1,2-pentylene carbonate, trans-2,3-pentyl carbonate, cis-2,3-pentyl carbonate, carbonic acid Cyclic carbonate compounds such as fluoroethylene carbonate, trifluoromethyl ethylene carbonate, and 4,5-difluoroethylene carbonate; and cyclic urea compounds such as 2-imidazolidinone. The cyclic carbonate compound is a compound represented by formula (I) and two Xs are oxygen atoms. The cyclic urea compound is a compound represented by formula (I) and two Xs are nitrogen atoms. The compound (C) preferably contains a cyclic carbonate compound, and more preferably contains at least one of the group consisting of ethylene carbonate and propylene carbonate. From the viewpoint of conductivity, the compound (C) preferably contains at least ethylene carbonate.

From the viewpoint of having both antistatic properties and low pollution properties, the compound (C) is preferably a compound having a melting point exceeding 25°C. Since it is not easy to flow out from the adhesive film, from the viewpoint of preventing contamination of the adherend caused by the adhesive film, a compound having a melting point of more than 25°C is preferred.

The adhesive composition may contain only one type of compound (C), or may contain two or more types of compound (C). Based on 100 parts by mass of the (meth)acrylic polymer (A) as a reference, the content of the compound (C) is preferably 0.2 part by mass or more, more preferably 0.5 part by mass or more, and still more preferably 1 part by mass or more . When the content of the compound (C) is 0.2 parts by mass or more, better antistatic properties can be obtained. Based on 100 parts by mass of the (meth)acrylic polymer (A) as a reference, the content of the compound (C) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 8 parts by mass or less . When the content of the compound (C) is 15 parts by mass or less, better low-contamination properties can be obtained.

[Crosslinking agent (D)] The adhesive composition may contain a crosslinking agent (D). The crosslinking agent (D), for example, preferably contains at least one selected from the group consisting of isocyanate compounds, epoxy compounds, (meth)acrylate compounds, and metal chelate compounds. From the viewpoint that the crosslinking reaction can be carried out by heating, the crosslinking agent (D), for example, more preferably contains at least one selected from the group consisting of isocyanate compounds and epoxy compounds, and still more preferably contains Isocyanate compound.

The isocyanate compound may be any isocyanate compound that is bifunctional or higher. The isocyanate compound preferably contains at least one selected from the group consisting of a difunctional isocyanate compound and a trifunctional or higher isocyanate compound. The isocyanate compound may contain only a difunctional isocyanate compound, or may contain only a trifunctional or higher isocyanate compound. The isocyanate compound may also contain a difunctional isocyanate compound and an isocyanate compound more than trifunctional.

The difunctional isocyanate compound may be one type or two or more types selected from compounds having two or more isocyanate (-NCO) groups in one molecule. Examples of difunctional isocyanate compounds include: aliphatic diisocyanates; aromatic diisocyanates; adducts of at least one selected from aliphatic diisocyanates and aromatic diisocyanates; selected from aliphatic diisocyanates Allophanate products of at least one of diisocyanate and aromatic diisocyanate, etc. "Addition product of at least one selected from aliphatic diisocyanates and aromatic diisocyanates", for example, is at least one selected from aliphatic diisocyanates and aromatic diisocyanates and a bifunctional polyvalent Alcohol adducts. A bifunctional polyol is a compound with two hydroxyl (-OH) groups in one molecule. As a bifunctional polyol, ethylene glycol, propylene glycol, etc. are mentioned.

As aliphatic diisocyanates, specific examples include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), hydrogenated xylene diisocyanate (H6XDI) and so on. Specific examples of aromatic diisocyanates include diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), dimethyl diphenylene diisocyanate (TOID), and toluene diisocyanate (TDI). )Wait.

The isocyanate compound having three or more functions may be selected from one or two or more compounds as long as it has 3 or more isocyanate groups in one molecule, and it is preferably selected as long as it has three isocyanate groups in one molecule. One type or two or more types of cyanate group compounds. Examples of trifunctional or higher isocyanate compounds include adducts of difunctional isocyanate compounds; isocyanurates of difunctional isocyanate compounds; biurets of difunctional isocyanate compounds. The "adduct of a difunctional isocyanate compound" is, for example, an adduct of a difunctional isocyanate compound and a trifunctional or higher polyol. A trifunctional or higher polyol is a compound having 3 or more hydroxyl (-OH) groups in one molecule. Examples of trifunctional or higher polyols include trimethylolpropane (TMP), glycerin, and the like.

Examples of isocyanate compounds include isocyanate compounds represented by the following formula (hereinafter, the isocyanate compound represented by formula (d1) may be referred to as "isocyanate compound (d1)". Regarding the formulas (d2) to (d6)) The isocyanate compound represented by any one of them is also the same).

In each formula, R each independently represents a divalent organic group, R ¹ represents a monovalent substituent, R ² represents a divalent organic group, and R ³ represents a trivalent organic group.

R is preferably a substituted or unsubstituted hydrocarbon group, more preferably: a linear or branched aliphatic hydrocarbon group; an alicyclic hydrocarbon group; or an aromatic hydrocarbon group. The aliphatic hydrocarbon group, alicyclic hydrocarbon group, and aromatic hydrocarbon group may be substituted or unsubstituted. The aliphatic hydrocarbon group is preferably an alkylene group. The carbon number of the aliphatic hydrocarbon group is preferably 1-22, more preferably 1-12, and still more preferably 1-8. The alicyclic hydrocarbon group is preferably a cycloalkylene group. The carbon number of the alicyclic hydrocarbon group is preferably 3-12, more preferably 5-8, and still more preferably 6. The carbon number of the aromatic hydrocarbon group is preferably 6-20, more preferably 6-10, and still more preferably 6. The aromatic hydrocarbon group may have at least one substituent selected from the group consisting of the following groups: a linear or branched aliphatic hydrocarbon group, and an alicyclic hydrocarbon group.

Examples of R include the following groups as hydrocarbon groups: methylene, ethylene, propylene, trimethylene, methylethylene, tetramethylene, 1-methyltrimethylene, 2-methyltrimethylene, pentamethylene, 1-methyltetramethylene, 2-methyltetramethylene, hexamethylene, 1-methylpentylene, 2-methylpentylene , 3-methylpentylene, 1-ethyltetramethylene, 2-ethyltetramethylene, heptamethylene, octamethylene and other linear or branched aliphatic hydrocarbon groups ; Cyclopentyl, cyclohexyl, cycloheptyl and other alicyclic hydrocarbon groups; phenylene, phenylene, xylylene, naphthyl and other aromatic hydrocarbon groups.

R ¹ may be a substituent containing a hydroxyl group. R ^{2 is} preferably a substituted or unsubstituted hydrocarbon group, preferably a substituted or unsubstituted alkylene group. R ^{3 is} preferably a substituted or unsubstituted hydrocarbon group, preferably an alkane triyl group. When the hydrocarbon group has a substituent, examples of the substituent include a hydroxyl group.

The isocyanate compound preferably includes at least one selected from the group consisting of isocyanate compounds (d1) to (d6), and more preferably includes at least one selected from the group consisting of isocyanate compounds (d2) to (d6) At least one of them. Especially from the viewpoint of obtaining good antistatic properties and adhesion, the isocyanate compound preferably contains at least one selected from the group consisting of isocyanate compounds (d3) and (d4), and more preferably contains isocyanate. Compound (d3).

When the adhesive composition contains the crosslinking agent (D), the content of the crosslinking agent (D) is preferably 0.1 parts by mass or more based on 100 parts by mass of the (meth)acrylic polymer (A) , More preferably 0.5 part by mass or more, still more preferably 1 part by mass or more. Based on 100 parts by mass of the (meth)acrylic polymer (A) as a reference, the content of the crosslinking agent (D) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass Servings or less. The composition for adhesives may contain one type of crosslinking agent (D) alone, or a combination of two or more types of crosslinking agents (D).

The adhesive composition may contain a hardening accelerator. The curing accelerator is preferably capable of promoting the reaction rate of the functional group contained in the (meth)acrylic polymer and the functional group contained in the curing agent (D). Here, the functional group refers to a (meth)acryloyl group, a hydroxyl group, a carboxyl group, an epoxy group, an isocyanate group, and the like.

As the hardening accelerator, for example, an organic metal compound, a tertiary amine compound, etc. can be used. Specifically, as the organometallic compound, tin-based catalysts such as dibutyltin dilaurate, dibutyltin dichloride, and dibutyltin oxide can be cited.

The adhesive composition may contain a solvent. The solvent is preferably an organic solvent. As the organic solvent, for example, formic acid, acetic acid, methanol, ethanol, propanol, methyl serosol, serosol, acetone, acetone, acetonitrile, hexane, benzene, toluene, methylene chloride, ethyl acetate Ester, butyl acetate, chlorobenzene, dichlorobenzene, etc.

[Other optional ingredients] The adhesive composition may contain other optional components. Examples of other optional components include surfactants, plasticizers, fillers, hardening retarders, processing aids, anti-aging agents, antioxidants, and the like. The composition for adhesives may contain one kind of other optional components alone, or a combination of two or more kinds of other optional components.

＜Adhesive film＞ The adhesive film as an embodiment of the present invention is a film obtained by using the aforementioned composition for adhesives. In the adhesive film, the (meth)acrylic polymer (A) may be crosslinked. The manufacturing method of an adhesive film is not specifically limited, A well-known manufacturing method may be sufficient. The adhesive film can be obtained, for example, by forming an adhesive composition layer on the surface of the support film, and drying and/or hardening the adhesive composition layer. Alternatively, the adhesive film can be formed according to, for example, an extrusion method. The adhesive film formed on the support film can be used after being peeled off from the support film, or it can be used as a laminate of the adhesive film and the support film without peeling from the support film.

A well-known coating method, a well-known printing method, etc. can be applied to the method of forming the composition layer for adhesive agents. Examples include: coating methods such as casting, spray coating, spin coating, dip coating, bar coating, chipped wheel coating, knife coating, die coating, etc.; gravure printing such as gravure printing; silk screen Printing methods such as stencil printing, etc.

The drying and hardening of the adhesive composition layer can be performed by heating. The heating temperature can be set to 50 to 150°C, for example. The heating time can be set to, for example, 1 minute to 10 hours.

The thickness of the adhesive film is not particularly limited. The thickness of the adhesive film is, for example, preferably 1 μm or more, more preferably 3 μm or more, and still more preferably 5 μm or more. When the thickness of the adhesive film is 1 μm or more, there is a tendency that sufficient strength can be maintained and good adhesiveness can be easily obtained. The thickness of the adhesive film is, for example, preferably 20 μm or less, more preferably 18 μm or less, and still more preferably 15 μm or less. When the thickness of the adhesive film is 20 μm or less, there is a tendency that sufficient flexibility can be maintained, the adhesive film becomes easy to follow the shape of the adherend, and it is easy to prevent the adhesive film from peeling off the adherend.

The surface resistivity of the adhesive film is preferably 1.0×10 ¹² Ω/□ or less, more preferably 5.0×10 ¹¹ Ω/□ or less, and still more preferably 2.5×10 ¹¹ Ω/□ or less. When the surface resistivity of the adhesive film is 1.0×10 ¹² Ω/□ or less, when the adhesive film is peeled from the adherend, the generation of static electricity due to charging can be effectively suppressed. As a result, when the adhesive film is peeled off from the adherend, the peeling electrostatic voltage caused by static electricity is reduced, and the influence on the adherend can be suppressed. If the peeling electrostatic voltage is high, problems may occur due to the following phenomena: the phenomenon that dust adheres to the adherend, the phenomenon that the circuit components arranged near the adherend are destroyed, and so on.

The adhesive film preferably has no adhesive attached to the adherend in the following evaluation. If the adhesive adheres, it may cause poor appearance of the adherend. Attach the adhesive film to the adherend, and leave it to stand for a specified time under high temperature and high humidity conditions of 85°C and 85% RH (RH: relative humidity). Then, the adhesive film was peeled from the adherend, and it was visually confirmed whether the adhesive had adhered to the adherend. The "prescribed time" can be set to 3 days, 20 days, or 40 days.

＜Surface protection film＞ The surface protection film of the embodiment of the present invention includes an adhesive film obtained by using the aforementioned composition for an adhesive, and a base film. The surface protection film may have any other film such as a cover film. Examples of surface protection films include: a surface protection film having a substrate film and an adhesive film, and the adhesive film is provided on one side of the substrate film; a surface protection film having a substrate film and an adhesive film And a cover film, the adhesive film is arranged on one surface of the base film, and the cover film is arranged on the surface of the adhesive film on the side opposite to the base film.

Fig. 1 is a schematic cross-sectional view showing an example of a surface protection film. In Figure 1, the surface protection film 1 has: a base film 4; an adhesive film 3, which is provided on one side of the base film 4; and, a cover film 2, which is provided on the adhesive film 3 and the base film 4 On the opposite side of the surface.

The substrate film preferably has a plastic film. The substrate film may have: a plastic film; and, any layer such as an antistatic layer, an antifouling layer, and an adhesion imparting layer, and the arbitrary layer is provided on at least one surface of the plastic film. When the substrate film has an antistatic layer and/or an antifouling layer, the antistatic layer and/or an antifouling layer are preferably provided on the surface of the substrate film on the opposite side of the adhesive film. The base film may have only one type of arbitrary layer, or may have a combination of two or more types of arbitrary layers.

Surface treatments such as antistatic treatment, antifouling treatment, adhesion imparting treatment, corona treatment, plasma treatment, etc. can be applied to at least one surface of the plastic film. As the antistatic treatment, coating and rubbing of an antistatic agent may be mentioned. When the base film is subjected to antistatic treatment and/or antifouling treatment, the antistatic treatment and/or antifouling treatment is preferably performed on the surface of the base film on the opposite side of the adhesive film. Only one surface treatment may be applied to the base film, or a combination of two or more surface treatments may be applied.

In the antistatic layer and the antistatic treatment, a known antistatic agent can be used. In the antifouling layer and antifouling treatment, known release agents such as silicon-oxygen-based mold release agents and fluorine-based mold release agents; and well-known antifouling agents such as silica microparticles can be used.

The plastic film is preferably a polyester film. The plastic film, for example, preferably includes at least one film selected from the group consisting of: polyethylene terephthalate (PET), cellulose triacetate (TAC), polyethylene naphthalate Ethylene Diester (PEN), Polymethyl Methacrylate (PMMA), Polycarbonate (PC), Polyimide (PI), Polyethylene (PE), Polypropylene (PP), Polyvinyl Alcohol (PVA) , Polyvinyl chloride (PVC), cyclic olefin copolymer (COC), cyclic olefin polymer (COP), containing norbornene resin, polyether ether, cellophane, and aromatic polyamide.

The thickness of the base film is not particularly limited. The thickness of the base film is, for example, preferably 10 μm or more, more preferably 30 μm or more, and still more preferably 50 μm or more. When the thickness of the base film is 10 μm or more, there is a tendency that sufficient strength can be maintained, and good film winding properties and processability are easily obtained. The thickness of the base film is, for example, preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less. When the thickness of the base film is 200 μm or less, there is a tendency that the surface protection film becomes easy to follow the shape of the adherend, and it is easy to prevent the surface protection film from peeling off the adherend.

The cover film preferably has a plastic film. The cover film preferably has a plastic film and a release layer, and the release layer is disposed on the surface of the plastic film on the side of the adhesive film. Alternatively, the surface of the plastic film on the side of the adhesive film is preferably subjected to a mold release treatment. In the mold release layer and mold release treatment, a known mold release agent such as a silicone-based mold release agent and a fluorine-based mold release agent can be used.

The plastic film, for example, preferably includes at least one selected from the group consisting of polymers and resins listed as examples of the plastic film in the description of the base film, and more preferably a polyester film.

The thickness of the cover film is not particularly limited. The thickness of the cover film is, for example, preferably 10 μm or more, more preferably 30 μm or more, and still more preferably 50 μm or more. The thickness of the cover film is, for example, preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less.

The manufacturing method of a surface protection film is not specifically limited, A well-known method may be sufficient. The surface protection film can be obtained by, for example, forming an adhesive film on one side of the base film. Specifically, a surface protection film can be obtained by, for example, forming an adhesive composition layer on one surface of a base film, and drying and/or curing the adhesive composition layer. Alternatively, the surface protection film can be formed according to, for example, a co-extrusion method.

As a method of forming an adhesive film, the manufacturing method of an adhesive film mentioned in the description of the said adhesive film can be used. What is necessary is just to use a base film instead of a support film in the manufacturing method of an adhesive film.

The object of protection of the surface protection film is not particularly limited. The surface protection film can be pasted and used in such a way that the surface on the side of the adhesive film is in contact with the protection object. When the surface protection film has a cover film, it is only necessary to peel off the cover film and then attach the surface protection film to the object to be protected. Examples of protection objects include optical components such as polarizing plates; liquid crystal display devices (LCD), plasma displays (PDP), cathode ray tubes (CRT), field emission displays (FED), organic electroluminescence displays, three-dimensional (3D) Display devices such as displays and electronic paper; automotive parts, home appliances parts, portable terminals, electronic parts, building materials, etc. [Example]

Hereinafter, the embodiments of the present invention will be explained with examples, but the present invention is not limited to these examples.

＜Manufacture of adhesive composition＞ [Example A1] In a reaction device equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen introduction tube, 90 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of 4-hydroxybutyl acrylate, and 50 parts by mass of acetic acid as a solvent were added Ethyl ester, 0.1 parts by mass of azobisisobutyronitrile as a polymerization initiator. Then, nitrogen was introduced, and it took 1 hour to replace the air in the reaction system with nitrogen. Then, the reaction was performed at 75°C for 7 hours to obtain a solution of (meth)acrylic polymer (A-1) having a weight average molecular weight of 500,000.

To the obtained (meth)acrylic polymer (A-1) solution (containing 100 parts by mass of the (meth)acrylic polymer (A-1)), 1 part by mass of lithium trifluoromethanesulfonate was added , And 3 parts by mass of ethylene carbonate, and stir. Then, 6.0 parts by mass of DURANATE AE700-100 (an allophanate of hexamethylene diisocyanate compound), 5.0 parts by mass of acetone, and 0.005 parts by mass of dibutyltin dilaurate were added and stirred, After mixing, ethyl acetate and butyl acetate (mass ratio 1:1) were further added to adjust the concentration, and the adhesive composition of Example A1 (non-volatile component concentration: 20% by mass) was obtained.

The weight average molecular weight of the (meth)acrylic polymer is a value measured by the gel permeation chromatography (GPC) method and converted from a calibration curve of standard polystyrene. The measurement conditions of the GPC method are as follows.

Device: manufactured by Tosoh Co., Ltd., trade name HLC-8320GPC (includes refractive index (RI) detector) Detector: RI (differential refractometer) Solvent: pure grade 1 tetrahydrofuran (THF) Protection column: trade name TSK-guard column Super MP(HZ)-H (1 branch) Protection column size: 4.6mm (inner diameter (ID)) × 20mm Column: manufactured by Tosoh Co., Ltd., trade name TSK-GEL Super Multipore HZ-H (3 connections) Column size: 4.6mm(ID)×150mm Temperature: 40℃ Sample concentration: 0.01g/5mL Injection volume: 10μL Flow rate: 0.35mL/min

The glass transition temperature (Tg) of the (meth)acrylic polymer is obtained based on the above-mentioned FOX formula. As the glass transition temperature of the homopolymer, the value described in the aforementioned "Introduction to Synthetic Resin for Paint" is used.

[Examples A2-10 and Comparative Examples A1-7] Except having used the monomer described in Table 1, it carried out similarly to Example A1, and obtained (meth)acrylic-type polymer (A-2)-(A-4). Then, except having used the components described in Tables 2 and 3, it carried out similarly to Example A1, and obtained the composition for adhesive agents of Examples A2 to A10 and Comparative Examples A1 to 7. The (meth)acrylic polymer (A-5) is "SK-Dyne (registered trademark) 1499M" manufactured by Soken Chemical Co., Ltd. Tables 1 to 3 show the amount of solid content (parts by mass) of each component.

[Table 1]

[Table 2]

[table 3]

The description of the abbreviated symbols used in Tables 1 to 3 is shown in Table 4.

[Table 4]

(B-1) and (B-2) are alkali metal salts whose melting points exceed 25°C and are solid at a temperature of 25°C. (b-1) is an alkaline earth metal salt whose melting point exceeds 25°C and is solid at a temperature of 25°C.

(C-1) is the compound (C) represented by the formula (I), and is a compound having a melting point of 36°C and a solid at a temperature of 25°C. (C-2) is a compound (C) represented by formula (I), and is a compound that has a melting point of -55°C and is liquid at a temperature of 25°C.

(c-1) to (c-3) are polyalkylene glycols, (c-1) and (c-2) are both liquid compounds at a temperature of 25°C. (c-3) is a polyalkylene glycol, and is a compound that is solid at a temperature of 25°C.

＜Production of surface protection film＞ [Example B1] The adhesive composition of Example A1 was coated on a polyethylene terephthalate (PET) film and heated at 110°C for 2 minutes to dry and harden, thereby forming an adhesive with a thickness of 10 μm film. Then, a polyethylene terephthalate (PET) film coated with silicone resin is laminated on the adhesive film to obtain a laminated film. The laminated film was aged at 40°C for 3 days to obtain the surface protective film of Example B1 having "PET film (base film)/adhesive film/silicone resin-coated PET film (cover film)".

[Examples B2 to B10 and Comparative Examples B1 to B7] In the same manner as in Example B1, the adhesive compositions of Examples A2 to A10 and Comparative Examples A1 to A7 were used to obtain surface protection films of Examples B2 to B10 and Comparative Examples B1 to B7.

＜Test method and evaluation＞ For the surface protection films of Examples B2 to B10 and Comparative Examples B1 to B7, the surface resistivity, adhesion, and low contamination of the adhesive films were evaluated. The evaluation results are shown in Tables 5 and 6.

<Surface resistivity> The evaluation is performed in an environment with a temperature of 23°C and a humidity of 50%RH. Peel the cover film from the surface protection film, and use a resistivity meter (manufactured by Mitsubishi Electric Co., Ltd., trade name: "Hiresta-UX MCP-HT800 high resistivity meter") to measure the surface resistivity of the adhesive film (Ω/ □). In Tables 5 and 6, "aE+b" means "a×10 ^b ".

＜Adhesion＞ The surface protection film was cut to obtain an evaluation film with a width of 25 mm and a length of 150 mm. The cover film was peeled off from the evaluation film, and the evaluation film was bonded to the glass plate so that the surface on the side of the adhesive film was in contact with the surface of the degreased glass plate to prepare a measurement sample. Use a tensile tester device (manufactured by Shimadzu Corporation, trade name: "AUTOGRAPH AG-X/R"), and evaluate under the conditions of room temperature (25°C), 180° direction, and a peeling speed of 300mm/min The film was peeled from the measurement sample, and the peel strength was measured. Let the obtained peel strength be adhesive force (N/25mm).

＜Low pollution＞ Using a pressing roller, a polarizing plate with an adhesive layer on one side (manufactured by Sumitomo Chemical Co., Ltd., trade name: "SUMIKARAN (registered trademark)" is applied so that the surface on the adhesive layer side of the polarizing plate is in contact with the surface of the glass plate. ) Stick on the glass plate. Then, using a pressing roller, the surface protection film was bonded to the polarizing plate so that the adhesive film was in contact with the surface of the polarizing plate to obtain a laminate. After storing the laminate in an environment of 85°C and 85% RH for 1 day, 3 days, 20 days, or 40 days, the surface protective film is peeled off. The contamination state of the surface of the polarizing plate after peeling was visually observed.

The evaluation criteria are as follows. "Contaminated" refers to the following state: the surface of the polarizing plate turns white and it is known to be contaminated at a glance; "somewhat slightly contaminated" refers to the following state: it appears to be uncontaminated at first glance, but near the end of the polarizing plate Or the vicinity of the bubble has turned white. When stored for 20 days and 40 days are "no pollution": 5 points "No pollution" when stored for 20 days, but "some slight pollution" when stored for 40 days: 4 points "No pollution" when stored for 3 days but "some slight pollution" when stored for 20 days: 3 points "Contaminated" when stored for 20 days: 2 points "Contaminated" when stored for 3 days: 1 point

[table 5]

[Table 6]

The surface protection films of Examples B1 to B10 all have surface resistivities below 1.0×10 ¹² Ω/□, and have excellent antistatic properties. In particular, the surface protection films of Examples B1 and B2 can obtain excellent adhesion to the adherend, and can have both high antistatic properties and high low pollution properties.

The surface protection films of Comparative Examples B1 to B3 did not exhibit excellent antistatic properties because the adhesive film did not contain the alkali metal salt (B) or the compound (C) represented by the formula (I). In addition, the surface protection films of Comparative Examples B4, B6, and B7 had poor low-staining properties. As one of the reasons, it is presumed that the alkanediol used in place of the alkali metal salt (B) and the compound (C) represented by the formula (I) caused minute cohesive failure of the adhesive film. In addition, in Comparative Example B5, since calcium carbonate was not dissolved in the adhesive composition, an adhesive film could not be produced.

The adhesive film formed using the adhesive composition of the embodiment of the present invention exhibits excellent adhesiveness, antistatic properties, and low pollution. The surface protective film provided with the adhesive film is suitable for protecting optical members and the like.

The disclosure of this case is related to the subject matter described in Japanese Patent Application No. 2019-086702 filed on April 26, 2019, and all the disclosures of this case are cited in this case.

1: Surface protection film 2: cover film 3: Adhesive film 4: Substrate film

Fig. 1 is a schematic cross-sectional view showing an example of a surface protection film as an embodiment.

Domestic deposit information (please note in the order of deposit institution, date and number) no Foreign hosting information (please note in the order of hosting country, institution, date, and number) no

1: Surface protection film

2: cover film

3: Adhesive film

4: Substrate film

Claims (5)

An adhesive composition containing a (meth)acrylic polymer (A), an alkali metal salt (B), and a compound (C) represented by formula (1),

In formula (I), X each independently represents an oxygen atom or a nitrogen atom, and R each independently represents a hydrogen atom, an alkyl group, or a fluoroalkyl group. The adhesive composition according to claim 1, which further contains a crosslinking agent (D). The adhesive composition according to claim 1 or 2, wherein the (meth)acrylic polymer (A) includes a structural unit derived from an alkyl (meth)acrylate monomer and derived from having a hydroxyl group Or a structural unit of (meth)acrylic monomer of carboxyl group. An adhesive film obtained by using the adhesive composition described in any one of claims 1 to 3. A surface protection film having an adhesive film and a substrate film, the adhesive film being obtained by using the adhesive composition described in any one of claims 1 to 3.

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