TW201425519A - Adhesive composition, adhesive film, and surface-protective adhesive film - Google Patents

Abstract

The present invention provides an adhesive composition, an adhesive film, and a surface-protective adhesive film that have excellent antistatic performance, that have excellent adhesive strength balance in the peel rate of a slow rate region and a high rate region, and that further also have excellent durability performance and reworking performance. In accordance with the present invention, an adhesive composition containing an antistatic agent, wherein the adhesive composition includes an acrylic-based polymer having, as the main component thereof, an alkyl (meth)acrylate having a C4 to C10 alkyl group; contains, with respect to 100 parts by weight of the acrylic-based polymer, 85 to 98.5 parts by weight of the main component alkyl (meth)acrylate, 0.1 to 15 parts by weight of a hydroxyl group-containing copolymerizable monomer, 0.1 to 2 parts by weight of a carboxyl group-containing copolymerizable monomer, and 0.1 to 5 parts by weight of a cross-linking agent; the acid value of the acrylic-based polymer is 0.01 to 8.0; and the antistatic agent is an ionic compound having a melting point of 30 to 50 DEG C and contains a polyether-modified siloxane compound, is provided.

Description

Adhesive composition, adhesive film and surface protective film

The present invention relates to an adhesive composition having antistatic properties and an adhesive film using the adhesive composition to form an adhesive layer having antistatic properties on at least one side of a resin film, and a surface protective film.

Further, the present invention relates to a surface protective film used in a manufacturing step of a liquid crystal display. More specifically, the present invention relates to an adhesive composition for a surface protective film which is adhered to a surface of an optical member such as a polarizing plate, a phase difference plate, and an antireflection film which constitute a liquid crystal display, and surface protection using the adhesive composition membrane.

In the manufacturing step of an optical member such as a polarizing plate, a phase difference plate, or an antireflection film which is a member constituting a liquid crystal display, a surface protective film for temporarily protecting the surface of the optical member is adhered. Such a surface protective film is used only in the step of manufacturing an optical member, and when the optical member is assembled to a liquid crystal display, it is removed from the optical member and removed. Since such a surface protective film for protecting the surface of the optical member is used only in the manufacturing step, it is also generally referred to as a "step film".

In the surface protective film used in the step of producing an optical member, an adhesive layer is formed on one surface of a polyethylene terephthalate (PET) resin film having optical transparency. A release-treated release film for protecting the adhesive layer is attached to the adhesive layer until it is attached to the optical member.

In addition, for optical members such as a polarizing plate, a phase difference plate, and an anti-reflection film, In the state of the surface protective film, product inspection is performed along with optical evaluation such as display performance, color tone, contrast, and impurity incorporation of the liquid crystal display panel. Therefore, as a performance requirement for the surface protective film, it is required that no air bubbles are present in the adhesive layer. No impurities were attached.

In addition, in recent years, when the surface protective film is peeled off from an optical member such as a polarizing plate, a retardation film, or an antireflection film, the static electricity generated by the static electricity generated when the adhesive layer is peeled off from the adherend may be affected. The failure of the electrical control circuit to the liquid crystal display requires that the adhesive layer have excellent antistatic properties.

Further, when the surface protective film is bonded to an optical member such as a polarizing plate, a retardation film, or an antireflection film, the surface protective film may be temporarily peeled off and the surface protective film may be reattached again for various reasons. At this time, the surface protective film is required to have a property (reworkability) which is easily peeled off from the optical member to be bonded. Further, at this time, it is required that the adhesive layer of the surface protective film does not contaminate the adherend, that is, the phenomenon that the so-called adhesive remains does not occur.

Further, when the surface protective film is peeled off from an optical member such as a final polarizing plate, a retardation film, or an antireflection film, it is required to be peeled off quickly. That is, it is required that the adhesion force is small due to the change in the peeling speed, so that it can be quickly peeled off even in the case of high-speed peeling.

As described above, in recent years, from the viewpoint of easy handling when using a surface protective film, it is required that the adhesive layer constituting the surface protective film has the following properties: (1) A balance of adhesion is obtained at a peeling speed in a low speed region and a high speed region. (2) Preventing the occurrence of adhesive residue; (3) having excellent antistatic properties; and (4) having rework performance.

However, even if the performance requirements for the adhesive layer constituting the surface protective film can be satisfied, that is, even if the individual performance requirements in the above (1) to (4) can be respectively satisfied, the adhesive layer which satisfies the surface protective film at the same time is satisfied. It is a very difficult subject to have all the performance requirements of (1) to (4).

In the present specification, the "low speed region" means a region in which the peeling speed is in the vicinity of 0.3 m/min; and the "high speed region" refers to a region in which the peeling speed is in the vicinity of 30 m/min.

For example, regarding (1) the balance of the adhesive force at the peeling speed of the low speed region and the high speed region, and (2) the prevention of the occurrence of the adhesive residue, the following proposals are known.

In the case of an alkyl (meth)acrylate having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing In the acrylic adhesive layer prepared by crosslinking a copolymer of a copolymerizable compound as a main component and crosslinking it with a crosslinking agent, the adhesive is applied to the adherend after a long time of bonding. There is a problem that the one side moves and adheres to the adherend, and the adhesion to the adherend is increased with time. In order to avoid this problem, there is known a technical solution in which an adhesive layer is used which uses an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms and an alcoholic hydroxyl group. An adhesive layer obtained by crosslinking a copolymer of a copolymerizable compound and crosslinking it with a crosslinking agent (Patent Document 1).

Further, there has been proposed a technical solution in which an adhesive layer is provided by blending a small amount of (meth)acrylic acid alkyl ester and a carboxyl group-containing copolymerization property in the same copolymer as described above. A copolymer of a compound and an adhesive layer obtained by crosslinking it with a crosslinking agent. However, when it is used for the surface protection of a plastic plate or the like having a low surface tension and a smooth surface, there is a problem of peeling phenomenon such as separation due to heating during processing or storage, and high-speed peeling in the field of manual operation. The problem of poor removability.

In order to solve these problems, an adhesive composition is proposed which is: a) a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms as a main component (methyl group) To 100 parts by weight of the alkyl acrylate, b) 1 to 15 parts by weight of a carboxyl group-containing copolymerizable compound, and c) 3 to 100 parts by weight of a vinyl group having 1 to 5 carbon atoms of an aliphatic carboxylic acid; An adhesive composition in which a copolymer of a monomer mixture is obtained by esterification, and a crosslinking agent having a carboxyl group equivalent or more of the above b) component is blended in the copolymer (Patent Document 2).

In the adhesive composition described in Patent Document 2, peeling phenomenon such as separation does not occur during processing or storage, and the adhesive strength is not greatly increased over time, and the removability is excellent. In addition, even if it is stored for a long period of time, especially in a high-temperature environment, it can be peeled off with a small force. At this time, no adhesive remains on the adhered body, and even in the case of high-speed peeling, it can be small. The power is then stripped.

In addition, as a method for imparting antistatic properties to the surface protective film, (3) excellent antistatic performance, a method of mixing an antistatic agent into a base film, or the like has been proposed. As the antistatic agent, for example, (a) a 4-stage ammonium salt, a pyridinium salt, various cationic antistatic agents having a cationic group such as a 1st to 3rd amino group; (b) a sulfonate group and a sulfate group are disclosed. Phosphate base, phosphonate base An anionic antistatic agent such as an anion group; (c) an amphoteric antistatic agent such as an amino acid or an aminosulfate; and (d) a nonionic antistatic agent such as an amino alcohol, a glycerin or a polyethylene glycol; (e) A polymer type antistatic agent obtained by polymerizing the antistatic agent as described above (Patent Document 3).

Further, in recent years, it has been proposed to include such an antistatic agent in a substrate film or directly in an adhesive layer instead of being applied to the surface of a substrate film.

Further, regarding (4) reworkability, for example, an adhesive composition is proposed which is a curing agent containing 0.0001 to 10 parts by weight of an isocyanate compound per 100 parts by weight of the acrylic resin. It is obtained by a specific citrate oligomer (Patent Document 4).

Patent Document 4 describes, as a main monomer, an alkyl acrylate having an alkyl group having a carbon number of 2 to 12 or an alkyl methacrylate having an alkyl group having a carbon number of 4 to 12 or so. The component may contain, for example, a monomer component containing another functional group such as a carboxyl group-containing monomer. In general, it is preferable to contain 50% by weight or more of the above-mentioned main monomer, and it is desirable that the content of the monomer component containing a functional group is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, more preferably 0.01 to 25 weight%. The adhesive composition described in Patent Document 4 has a small change in the cohesive force and the adhesive force over time even under high temperature or high temperature and high humidity, and exhibits an excellent effect on the adhesion of the curved surface, and thus has an additional effect. Processability.

In general, when the adhesive layer is soft, the adhesive remains easily and the reworkability is easily lowered. That is, it is difficult to peel off after the wrong bonding, and it is difficult to re-stick. From this point of view, in order to impart reworkability, it is necessary to crosslink a monomer having a functional group such as a carboxyl group to the main component so that the adhesive layer has a certain hardness.

In the prior art, as a performance requirement for an adhesive layer constituting a surface protective film, it has been conventionally required to have (1) balance of adhesion at a peeling speed of a low speed region and a high speed region; (2) prevention of adhesion The occurrence of agent residues; (3) excellent antistatic properties; and (4) reworkability. However, even if the performance requirements of the individual items (1) to (4) above can be satisfied, the performance requirements of the adhesive layer of the surface protective film cannot be satisfied.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. SHO 63-225677

[Patent Document 2] Japanese Patent Laid-Open No. Hei 11-256111

[Patent Document 3] Japanese Patent Laid-Open No. Hei 11-070629

[Patent Document 4] Japanese Patent Laid-Open No. Hei 8-199130

The present invention has been made in view of the above circumstances, and an object thereof is to provide an excellent antistatic property, excellent balance of adhesion at a peeling speed in a low speed region and a high speed region, and excellent durability and reworkability. Adhesive composition, adhesive film and surface protective film.

In order to solve the above problems, the present invention provides an adhesive composition which is an adhesive composition containing an antistatic agent, wherein the adhesive composition contains an alkyl group having a carbon number of 4 to 10 (methyl group). The acrylic polymer having an alkyl acrylate as a main component contains 85 to 98.5 parts by weight of the main component, that is, alkyl (meth) acrylate, 0.1 to 15 parts by weight based on 100 parts by weight of the acrylic polymer. a hydroxyl group-containing copolymerizable monomer, 0.1 to 2 parts by weight of a carboxyl group-containing copolymerizable monomer, and 0.1 to 5 parts by weight of a crosslinking agent, and the acrylic polymer has an acid value of 0.01 to 8.0. The antistatic agent is an ionic compound having a melting point of 30 to 50 ° C, and the adhesive composition contains a polyether modified siloxane compound.

Further, the above-mentioned main component, that is, an alkyl (meth)acrylate is preferably selected from the group consisting of butyl (meth)acrylate, isobutyl (meth)acrylate, amyl (meth)acrylate, (methyl). Hexyl acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, ( Isodecyl methacrylate, decyl (meth) acrylate More than one of the group of compounds.

Further, the hydroxyl group-containing copolymerizable monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and (meth)acrylic acid 4. -hydroxybutyl ester, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)propene At least one or more of the group consisting of guanamines.

Further, the carboxyl group-containing copolymerizable monomer is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and 2-(methyl)acrylonitrile. Ethyl hexahydrophthalic acid, 2-(methyl) propylene methoxypropyl hexahydrophthalic acid, 2-(methyl) propylene methoxyethyl phthalate, 2-(A Acryloxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene decyloxy One or more of the group consisting of ethyltetrahydrophthalic acid.

Further, it is preferred that the polyether-modified siloxane compound is a polyether-modified siloxane compound having an HLB value of 7 to 12.

Further, it is preferred that the crosslinking agent is a trifunctional or higher isocyanate compound.

Further, the present invention provides an adhesive film which is formed by forming an adhesive layer on one side or both sides of a resin film, and the adhesive layer is obtained by crosslinking the above-mentioned adhesive composition.

Further, the present invention provides a surface protective film which is formed by forming an adhesive layer on one surface of a resin film, and the adhesive layer is formed by crosslinking the above-mentioned adhesive composition.

According to the present invention, it is possible to satisfy all the properties required for the adhesive layer of the surface protective film which cannot be solved in the prior art. Moreover, excellent antistatic properties can be obtained and the occurrence of adhesive residue can be prevented.

Hereinafter, the present invention will be described based on preferred embodiments.

The adhesive composition of the present invention is an adhesive composition containing an antistatic agent, characterized in that the adhesive composition contains an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms. The acrylic polymer containing the ester as a main component contains 85 to 98.5 parts by weight of the main component, that is, alkyl (meth)acrylate, and 0.1 to 15 parts by weight of the hydroxyl group, based on 100 parts by weight of the acrylic polymer. a copolymerizable monomer, 0.1 to 2 parts by weight of a carboxyl group-containing copolymerizable monomer, and 0.1 to 5 parts by weight of a crosslinking agent, the acrylic polymer having an acid value of 0.01 to 8.0, and the antistatic agent is An ionic compound having a melting point of 30 to 50 ° C, and the adhesive composition contains a polyether modified siloxane compound.

The alkyl (meth)acrylate as a main component is preferably an alkyl (meth)acrylate containing an alkyl group having 4 to 10 carbon atoms, preferably selected from (meth)acrylic acid. Ester, isobutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate One or more of the group consisting of an ester, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and decyl (meth)acrylate.

The content of the alkyl (meth)acrylate as a main component is preferably from 85 to 98.5 parts by weight based on 100 parts by weight of the acrylic polymer.

Examples of the hydroxyl group-containing copolymerizable monomer include hydroxyalkyl (meth)acrylates and (meth)acrylamides containing hydroxyl groups.

Preferably, the hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. (Methacrylate a group of compounds consisting of 2-hydroxyethyl ester, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide At least one or more.

The content of the hydroxyl group-containing copolymerizable monomer is preferably 0.1 to 15 parts by weight based on 100 parts by weight of the acrylic polymer.

The carboxyl group-containing copolymerizable monomer is preferably selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and 2-(methyl)acrylonitrile. Ethyl hexahydrophthalic acid, 2-(methyl) propylene methoxypropyl hexahydrophthalic acid, 2-(methyl) propylene methoxyethyl phthalate, 2-(A Acryloxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene decyloxy One or more of the group consisting of ethyltetrahydrophthalic acid.

The content of the carboxyl group-containing copolymerizable monomer is preferably 0.1 to 2 parts by weight based on 100 parts by weight of the acrylic polymer.

For the adhesive composition of the present invention, it is preferred to crosslink the adhesive polymer when the adhesive layer is formed. As a method of initiating the crosslinking reaction, crosslinking may be carried out by photocrosslinking such as ultraviolet rays (UV), but it is preferred that the adhesive composition contains a crosslinking agent.

Examples of the crosslinking agent include a difunctional or trifunctional or higher isocyanate compound, a difunctional or trifunctional or higher epoxide, a difunctional or trifunctional or higher acrylate compound, a metal chelate compound, and the like. Among them, a polyisocyanate compound (difunctional or trifunctional or higher isocyanate compound) is preferred, and a trifunctional or higher isocyanate compound is more preferred.

The content of the crosslinking agent is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the above acrylic polymer.

The trifunctional or higher isocyanate compound may be a polyisocyanate compound having at least three or more isocyanate (NCO) groups in one molecule. The polyisocyanate compound includes a classification of an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an alicyclic isocyanate, and the like, and the present invention may be any of them. Specific examples of the polyisocyanate compound include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). ;two Phenylmethane diisocyanate (MDI), benzodimethyl diisocyanate (XDI), hydrogenated dimethyl diisocyanate (H6XDI), dimethyl diphenylene diisocyanate (TOID), toluene diisocyanate (TDI), etc. An aromatic isocyanate compound.

Examples of the trifunctional or higher isocyanate compound include a biuret modified product or a isocyanurate modified product of a diisocyanate (a compound having two NCO groups in one molecule), and a trimethylol group. An adduct (polyol modified product) of a trivalent or higher polyvalent alcohol (a compound having at least three or more OH groups in one molecule) such as propane (TMP) or glycerin.

In order to impart antistatic properties, it is preferred that the adhesive composition of the present invention contains an antistatic agent. The antistatic agent is preferably a solid at normal temperature (for example, 30 ° C). More specifically, the antistatic agent is an ionic compound having a melting point of 30 to 50 °C. The antistatic agent may be a 4-stage ammonium salt type ionic compound containing an acrylonitrile group.

Since these antistatic agents have a low melting point and a long-chain alkyl group, they are presumed to have high affinity with an acrylic polymer.

The antistatic agent having an ionic compound having a melting point of 30 to 50 ° C is an ionic compound having a cation and an anion, and examples of the cation include a pyridinium cation, an imidazolium cation, a pyrimidine cation, a pyrazolium cation, and pyrrolidinium. (pyrrolidinium) a nitrogen-containing phosphonium cation such as a cation or an ammonium cation, or a phosphonium cation or a phosphonium cation, and the anion is a hexafluorophosphate (PF ₆ ^- ), a thiocyanate (SCN ^- ), an alkylbenzenesulfonate (RC). A compound of an inorganic or organic anion such as ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ) or tetrafluoroborate (BF ₄ ^- ). A compound having a melting point of 30 to 50 ° C can be obtained by selecting the chain length of the alkyl group, the position and number of the substituents, and the like. Preferably, the cation is a 4-stage nitrogen-containing phosphonium cation, and a 4-stage pyridinium cation such as 1-alkylpyridinium (having a substituent or a substituent at a carbon atom of 2 to 6) may be mentioned. a 4-stage imidazolium cation such as a 1,3-dialkylimidazolium (a carbon atom at the 2, 4, or 5 position may have a substituent or a substituent), or a 4-stage ammonium cation such as a tetraalkylammonium. .

The content of the antistatic agent as the ionic compound having a melting point of 30 to 50 ° C is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of the acrylic polymer.

The quaternary ammonium salt-type ionic compound containing an acrylonitrile group is an ionic compound having a cation and an anion, and the cation is a (meth) propylene decyloxyalkyltrialkylammonium (R ₃ N ⁺ - C _n H _2n -OCOCQ=CH ₂ , wherein Q=H or CH ₃ , R=alkyl), etc., contains 4-methylammonium (meth) acrylonitrile, and anion is hexafluorophosphate (PF ₆ ^- ), thiocyanate (SCN ^- ), organic sulfonate (RSO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), F-containing quinone (R ^F ₂ A compound of an inorganic or organic anion such as N ^- ). (PEI) containing a root of F (R ^F ₂ N ^-) of R & lt ^F, include trifluoromethanesulfonic acyl, sulfo pentafluoroethyl acyl group such as a perfluoroalkyl sulfonic acyl, sulfo-fluoro-acyl. As the F-containing quinone imine root, bis(fluorosulfonyl) ruthenium root [(FSO ₂ ) ₂ N ^- ], bis(trifluoromethanesulfonyl) fluorenylene root [(CF _{3 )]} SO ₂ ) ₂ N ^- 〕, bis(sulfonyl sulfonyl) ruthenium root [(C ₂ F ₅ SO ₂ ) ₂ N ^- ), etc.

It is preferable that the quaternary ammonium salt type ionic compound containing an acrylonitrile group is copolymerized in the acrylic polymer in an amount of 0.1 to 5.0% by weight.

Specific examples of the antistatic agent are not particularly limited, but specific examples of the ionic compound having a melting point of 30 to 50 ° C include 1-octylpyridinium dodecylbenzenesulfonate and 1-12. Alkylpyridinium thiocyanate, 3-methyl-1-dodecylpyridinium hexafluorophosphate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1 - Octylpyridinium hexafluorophosphate or the like.

Further, specific examples of the quaternary ammonium salt type ionic compound containing an acrylonitrile group include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ ‧PF ₆ ^- , wherein Q=H or CH ₃ ], dimethylaminoethyl (meth) acrylate bis(trifluoromethanesulfonyl) quinone imine methyl salt [( CH ₃ ) ₃ N ⁺ (CH ₂ ) ₂ OCOCQ=CH ₂ ‧(CF ₃ SO ₂ ) ₂ N ^- , wherein Q=H or CH ₃ ], dimethylaminomethyl (meth) acrylate double ( Fluroxysulfonyl) quinone imine methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ ‧ (FSO ₂ ) ₂ N ^- , wherein Q = H or CH ₃ ] and the like.

The adhesive composition of the present invention contains a polyether modified siloxane compound. The polyether-modified siloxane compound is a siloxane compound having a polyether group, and includes a siloxane group having a polyether group in addition to the usual siloxane unit [-SiR ¹ ₂ -O-]. -SiR ¹ (R ² O(R ³ O) _n R ⁴ )-O-]. Here, R ¹ represents one or two or more alkyl groups or aryl groups, R ² and R ³ represent one or two or more alkylene groups, and R ⁴ represents one or two or more alkyl groups, fluorenyl groups and the like ( End base). The polyether group may, for example, be a polyoxyalkylene group such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] or a polyoxypropylene group [(C ₃ H ₆ O) _n ].

Preferably, the polyether modified siloxane compound is a polyether modified siloxane compound having an HLB value of 7 to 12. Further, the content of the polyether-modified siloxane compound is preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the acrylic polymer. More preferably, it is 0.1 to 0.5 parts by weight.

HLB is a hydrophilic-lipophilic balance (a ratio of hydrophilicity to lipophilicity) prescribed in, for example, JIS K3211 (surfactant terminology).

The polyether-modified oxoxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane having a decyl group by a hydrogenation oximation reaction. Obtained from the main chain. Specifically, a dimethyl methoxy oxane-methyl (polyoxyethylene) decane copolymer, dimethyl methoxy oxane-methyl (polyoxyethylene) decane-methyl (poly) A propylene oxide) siloxane copolymer, a dimethyl methoxy oxane-methyl (polyoxypropylene) siloxane copolymer, or the like.

By blending the above polyether-modified siloxane compound with the adhesive composition, the adhesion and reworkability of the adhesive can be improved.

The adhesive composition of the present invention may contain a crosslinking inhibitor. Examples of the crosslinking inhibitor include methyl acetonitrile acetate, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, stearyl acetate, and the like. Β -ketoester, β -diketone such as acetamidineacetone, 2,4-hexanedione, benzamidineacetone or the like. These are ketoenol tautomer compounds, and in the adhesive composition using a polyisocyanate compound as a crosslinking agent, by blocking the isocyanate group which the crosslinking agent has, it is possible to suppress the adhesive composition after the crosslinking agent is blended. The excessive increase in viscosity or gelation can prolong the shelf life of the adhesive composition.

Preferably, the crosslinking inhibitor is a ketoenol tautomer compound, and particularly preferably at least one selected from the group consisting of ethyl acetonide and ethyl acetate.

In the case where the crosslinking inhibitor is added, the content of the crosslinking inhibitor relative to 100 parts by weight of the acrylic polymer is preferably 1.0 to 5.0 parts by weight.

The adhesive composition of the present invention may contain a crosslinking catalyst. When a polyisocyanate compound is used as a crosslinking agent, the crosslinking catalyst may be a substance which acts as a catalyst for the reaction (crosslinking reaction) of the acrylic polymer and the crosslinking agent. Examples of the crosslinking catalyst include an amine compound such as a tertiary amine, an organic tin compound such as an organic tin compound, an organic lead compound, and an organic zinc compound.

Examples of the tertiary amine include a trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, and triethylenediamine. Phenanthene derivative Derivatives, etc.

Examples of the organotin compound include a dialkyl tin oxide, a fatty acid salt of a dialkyl tin, and a fatty acid salt of tin (II).

Preferably, the crosslinking catalyst is an organotin compound, and particularly preferably at least one selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate.

When the crosslinking catalyst is added, the content of the crosslinking catalyst is preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the acrylic polymer.

The adhesive composition of the present invention may contain a polyether compound. The polyether compound is a compound having a polyalkylene oxide, and examples thereof include polyether polyols such as polyalkylene glycols and derivatives thereof. The alkylene group contained in the polyalkylene glycol and the polyalkylene oxide may, for example, be an ethylene group, a propylene group or a butylene group, but is not limited thereto. The polyalkylene glycol may be a copolymer of two or more kinds of polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of the copolymer of polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene. The diol or the like may be a block copolymer or a random copolymer.

Examples of the derivative of the polyalkylene glycol include a polyoxyalkylene alkyl ether such as a polyoxyalkylene monoalkyl ether or a polyoxyalkylene dialkyl ether, and a polyoxyalkylene group. A polyoxyalkylene alkenyl ether such as an alkenyl ether or a polyoxyalkylene dialkyl ether; a polyoxyalkylene aryl group such as a polyoxyalkylene monoaryl ether or a polyoxyalkylene diaryl ether; Polyoxyalkylene glycol fatty acid esters such as ether, polyoxyalkylene alkylphenyl ether, polyoxyalkylene glycol mono fatty acid ester, polyoxyalkylene glycol di fatty acid ester, polyoxidation An alkylene sorbitan fatty acid ester, a polyoxyalkylene alkylamine, a polyoxyalkylene diamine or the like.

Here, examples of the alkyl ether in the polyalkylene glycol derivative include a lower alkyl ether such as methyl ether or diethyl ether, and a higher alkyl ether such as lauryl ether or octadecyl ether. Examples of the alkenyl ether in the polyalkylene glycol derivative include a vinyl ether, an allyl ether, and an oleyl ether. Further, examples of the fatty acid ester in the polyalkylene glycol derivative include saturated fatty acid esters such as acetate and stearate, and unsaturated fatty acid esters such as (meth) acrylate and oleate. .

Preferably, the polyether compound is a compound containing an ethylene oxide, more preferably A compound containing a polyoxyethylene group.

When the polyether compound has a polymerizable functional group, it can also be copolymerized with a (meth)acrylic polymer. The polymerizable functional group is preferably an ethylenic functional group such as a (meth)acryl group, a vinyl group or an allyl group. Examples of the polyether compound having a polymerizable functional group include polyalkylene glycol mono(meth)acrylate, polyalkylene glycol di(meth)acrylate, and alkoxypolyalkylene II. Alcohol (meth) acrylate, polyalkylene glycol monoallyl ether, polyalkylene glycol diallyl ether, alkoxy polyalkylene glycol allyl ether, polyalkylene glycol single Vinyl ether, polyalkylene glycol divinyl ether, alkoxy polyalkylene glycol vinyl ether, and the like.

Further, as another component, a copolymerizable (meth)acrylic monomer, a (meth)acrylamide monomer, a dialkyl-substituted acrylamide monomer, which contains an alkylene oxide, may be appropriately blended. A known additive such as a surfactant, a curing accelerator, a plasticizer, a filler, a curing inhibitor, a processing aid, an anti-aging agent, and an antioxidant. These may be used alone or in combination of two or more.

By copolymerizing a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 10 carbon atoms and a hydroxyl group-containing copolymerizable monomer and a carboxyl group-containing copolymerizable monomer, it can be synthesized and used as the adhesive of the present invention. An acrylic polymer of the main component of the agent composition. The polymerization method of the acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.

In the acrylic polymer, a polyalkylene glycol mono(meth)acrylate monomer, a hydroxyl group-free nitrogen-containing vinyl monomer, and an alkoxy group-containing (meth)acrylic acid alkyl group may also be used. Other monomers such as an ester monomer and a quaternary ammonium salt type ionic compound containing an acryloyl group are copolymerized.

The adhesive composition of the present invention can be formulated by blending a crosslinking agent, an antistatic agent, and any appropriate additives in the above acrylic polymer.

Further, it is preferred that the acrylic polymer has an acid value of 0.01 to 8.0. Thereby, it is possible to improve the staining property and improve the performance of preventing the occurrence of the adhesive residue.

Here, the "acid value" is one of the indexes indicating the acid content, and is expressed by the number of mg of potassium hydroxide required to neutralize 1 g of the carboxyl group-containing polymer.

Preferably, the adhesive layer obtained by crosslinking the adhesive composition has an adhesive force of 0.3 to 0.1 N/25 mm at a peeling speed of 0.3 m/min in a low speed region, and a peeling speed of 30 m/min at a high speed region. The adhesion is 1.0N/25mm or less. Thereby, it is possible to obtain a performance in which the change in the adhesive force with the peeling speed is small, and it is possible to quickly peel off even in the case of high-speed peeling. Further, even if the surface protective film is temporarily peeled off for re-adhesion, it does not require excessive force and is easily peeled off from the adherend.

Preferably, the adhesive layer obtained by crosslinking the adhesive composition has a surface resistivity of 5.0 × 10 ^{+ 11} Ω / □ or less, and a peeling static voltage of ± 0 to 0.5 kV. Further, in the present invention, the term "±0 to 0.5 kV" means "0 to -0.5 kV" and "0 to +0.5 kV", that is, "-0.5 to +0.5 kV". When the surface resistivity of the adhesive layer is large, when the surface protective film is peeled off, the adhesive layer releases poor static electricity due to charging. By making the surface resistivity of the adhesive layer sufficiently small, it is possible to reduce the peeling static voltage caused by static electricity generated when the adhesive layer is peeled off from the adherend, and it is possible to suppress the influence on the electric control circuit or the like of the adherend.

It is preferred that the adhesive layer (adhesive after crosslinking) obtained by crosslinking the adhesive composition of the present invention has a gel fraction of 95 to 100%. Since the gel fraction is so high, the adhesion does not become excessive at a low peeling speed, and the phenomenon of eluting unpolymerized monomers or oligomers from the acrylic polymer is lowered, thereby improving reworkability and high temperature. / Durability under high humidity and inhibit contamination by adherends.

The adhesive film of the present invention is formed by forming an adhesive layer on one or both sides of a resin film which is obtained by crosslinking the adhesive composition of the present invention. Further, the surface protective film of the present invention is obtained by forming an adhesive layer on one side of a resin film which is obtained by crosslinking the adhesive composition of the present invention. In the adhesive composition of the present invention, since the components of the acrylic polymer are blended with good balance, the antistatic property is excellent, and the balance of adhesion at a peeling speed in a low-speed region and a high-speed region is excellent. excellent. Further, the durability and the reworkability were also excellent (after the ink pen was drawn on the surface protective film via the adhesive layer, no contamination was transferred to the adherend). Therefore, it can be preferably used as a polarizing plate, a phase difference plate, and an anti-reflection film. The surface protective film is used for use.

As the base film of the adhesive layer and the release film (separator) which protects the adhesive surface, a resin film such as a polyester film or the like can be used.

In the base film, the surface of the resin film opposite to the side on which the adhesive layer is formed can be prevented by a release agent, a coating agent, cerium oxide particles or the like of an anthrone or a fluorine-based release agent. For the stain treatment, an antistatic treatment by coating or mixing of an antistatic agent or the like can be performed.

In the release film, a release treatment by an anthrone or a fluorine release agent is performed on the surface on the side where the adhesive surface of the adhesive layer is bonded.

[Examples]

Hereinafter, the present invention will be specifically described based on examples.

<Manufacture of acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction apparatus with nitrogen. Then, 90 parts by weight of 2-ethylhexyl acrylate, 9 parts by weight of 8-hydroxyoctyl acrylate, 1.0 part by weight of acrylic acid, and 60 parts by weight of a solvent (ethyl acetate) were simultaneously added to the reaction apparatus. . Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain an acrylic acid used in Example 1 having a weight average molecular weight of 500,000. Polymer-like solution 1. A part of the acrylic polymer was used as an acid value measurement sample to be described later.

[Examples 2 to 6 and Comparative Examples 1 to 3]

Except that the composition of each monomer was adjusted in each of (A) to (C) in Table 1, the same procedure as in the above-described acrylic polymer solution 1 used in Example 1 was carried out, and Example 2 was obtained. 6 and the acrylic polymer solution of Comparative Examples 1 to 3.

Further, in Tables 1 and 2, (A) is a (meth)acrylic acid alkyl ester as a main component, (B) is a hydroxyl group-containing copolymerizable monomer, and (C) is a carboxyl group-containing copolymerizable property. monomer.

【Table 1】

<Manufacture of Adhesive Composition and Surface Protective Film>

[Example 1]

To the acrylic polymer solution 1 of Example 1 produced as described above, 2.0 parts by weight of 1-octylpyridinium dodecylbenzenesulfonate and 0.1 part by weight of KF-351A (HLB=12) were added. After the polyether-modified oxoxane compound was stirred, 1.0 part by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound) was added, followed by stirring and mixing, and the adhesive composition of Example 1 was obtained. Things. The adhesive composition was applied onto a release film composed of a polyethylene terephthalate (PET) film coated with an fluorenone resin, and then dried at 90 ° C to remove the solvent to obtain an adhesive layer. Adhesive sheet having a thickness of 25 μm.

Then, prepare a polyethylene terephthalate with antistatic treatment and antifouling treatment on one side. a glycol ester (PET) film, and transferring the adhesive sheet to the opposite side of the surface of the polyethylene terephthalate (PET) film which is subjected to antistatic treatment and antifouling treatment, and obtained A surface protective film of Example 1 in which a PET film/adhesive layer/release film (PET film coated with an oxime resin) having an antistatic treatment and an antifouling treatment was laminated.

[Examples 2 to 6 and Comparative Examples 1 to 3]

Surface protection of Examples 2 to 6 and Comparative 1 to 3 was obtained in the same manner as in the surface protective film of Example 1 except that the composition of each additive was adjusted as shown in (D) to (F) of Table 2, respectively. membrane.

Further, in Tables 1 and 2, (D) is a crosslinking agent, (E) is an antistatic agent, and (F) is a polyether modified siloxane compound.

In Table 1, the numerical values in the parentheses indicate the numerical values of the respective component parts by weight obtained by setting the total weight of the group (A) to (C) to 100 parts by weight. Further, the compound names corresponding to the abbreviations of the respective components used in Table 1 are shown in Table 2. Further, Coronate (registered trademark) HX, Coronate HL and Coronate L are trade names of Nippon Polyurethane Industry Co., Ltd., Takenate (registered trademark) D-140N, D-127N, D -11ON and D-120N are trade names of Mitsui Chemicals Co., Ltd., and KF-351A, KF-352A, KF-353, KF-640, and X-22-6191 are trade names of Shin-Etsu Chemical Co., Ltd.

<Test method and evaluation>

Surface protection of Examples 1 to 6 and Comparative Examples 1 to 3 in an environment of 23 ° C and 50% RH After the film was aged for 7 days, the release film (PET film coated with an anthrone resin) was peeled off to expose the adhesive layer, and it was used as a sample for measuring the surface resistivity.

Further, the surface protective film exposed to the adhesive layer was bonded to the surface of the polarizing plate adhered to the liquid crystal cell through an adhesive layer, and left for 1 day, and then subjected to autoclave treatment at 50 ° C and 5 atm for 20 minutes. Further, it was allowed to stand at room temperature for 12 hours, and the surface protective film thus obtained was used as a sample for measuring adhesion, peeling static voltage, reworkability, and durability.

<acid value>

Acid value of acrylic polymer: The sample is dissolved in a solvent (a solvent in which diethyl ether and ethanol are mixed at a volume ratio of 2:1), and an electric potential difference automatic titrator (AT-610, Kyoto Electronics Industry Co., Ltd.) is used. Manufactured, potentiometric titration was carried out with a potassium hydroxide ethanol solution having a concentration of about 0.1 mol/L, and the amount of the potassium hydroxide ethanol solution required for neutralizing the sample was measured. Then, the acid value was determined according to the following formula.

Acid value = (B × f × 5.611) / S

B = amount of 0.1 mol/L potassium hydroxide ethanol solution used in the titration (mL)

f=0.1mol/L coefficient of potassium hydroxide ethanol solution

S = mass of solid component of sample (g)

<adhesion>

Using a tensile tester, the above-obtained measurement sample was peeled off in a 180° direction at a peeling speed (0.3 m/min) in a low speed region and a peeling speed (30 m/min) in a high speed region (a 25 mm wide surface protective film was used) The sample which was bonded to the surface of the polarizing plate was measured for peel strength, and the peel strength was used as an adhesive force.

<surface resistivity>

After aging, before adhering to the polarizing plate, peeling off the peeling film (PET film coated with fluorenone resin) to expose the adhesive layer, using a resistivity meter (trade name "Hiresta UP-HT450", (share) The surface resistivity of the adhesive layer was measured by Mitsubishi Chemical Analytech Co., Ltd., manufactured by Mitsubishi Chemical Analytech Co., Ltd.

<peeling static voltage>

A high-precision electrostatic sensor (model: SK-035, SK-200, manufactured by Keyence Corporation) was used to measure a tensile speed of 30 m/min for the above-obtained measurement sample. When 180° peeling is performed, the voltage (static voltage) generated when the polarizing plate is charged is used, and the maximum value of the measured value is taken as the peeling static voltage.

<Reworkability>

The surface protective film of the measurement sample obtained above was drawn with a ball pen (loading was 500 g, three times back and forth), and the surface protective film was peeled off from the polarizing plate, and the surface of the polarizing plate was observed, and it was confirmed that no contamination was transferred to the polarizing plate. Evaluation criteria for reworkability: evaluated as "○" when no contamination was transferred to the polarizing plate; "△" when it was confirmed that the trajectory drawn along the atomic pen was at least partially transferred; when it was confirmed to be drawn along the atomic pen The trajectory has a contamination shift and is evaluated as "x" when the adhesion of the adhesive is also confirmed from the surface of the adhesive. The reworkability was evaluated based on the above criteria.

<Durability>

After the measurement sample obtained above was placed in an environment of 60 ° C and 90% RH for 250 hours, it was taken out and left at room temperature for further 12 hours, and then the adhesion was measured, and it was confirmed that there was no significant difference compared with the initial adhesion. increase. Evaluation criteria of durability: When the adhesion after the test was 1.5 times or less of the initial adhesion, it was evaluated as "○", and when it was more than 1.5 times, it was evaluated as "X". Durability was evaluated based on the above criteria.

The evaluation results are shown in Table 3. Further, the surface resistivity by "mE + n" to represent "m × 10 ^{+ n"} (where, m is an arbitrary real numbers, n-is a positive integer).

【table 3】

For the surface protection films of Examples 1 to 6, the adhesion at a peeling speed of 0.3 m/min in a low speed region was 0.05 to 0.1 N/25 mm, and the adhesion at a peeling speed of 30 m/min in a high speed region was 1.0. Below N/25 mm, the surface resistivity is 5.0 × 10 ⁺¹¹ Ω/□ or less, and the peeling static voltage is ±0 to 0.5 kV. Further, after drawing with the surface protective film through the adhesive layer via the adhesive pen, the adhesive was not transferred to the adherend, and the durability after leaving it in an environment of 60° C. and 90% RH for 250 hours was also excellent.

That is, all of the following performance requirements are satisfied: (1) achieving the balance of adhesion at the peeling speed of the low speed region and the high speed region; (2) preventing the occurrence of adhesive residue; (3) having excellent antistatic properties. And (4) have reworkability.

The surface protective film of Comparative Example 1 may be because the (meth)acrylic acid alkyl ester as a main component is too small, the hydroxyl group-containing copolymerizable monomer is excessive, and the copolymerizable monomer having a carboxyl group is not contained, and When the HLB value of the polyether-modified siloxane compound is too small, the adhesion rate at a peeling speed of 0.3 m/min in a low-speed region is small, the surface resistivity and the peeling static voltage are high, and durability is poor.

In the surface protective film of Comparative Example 2, since the carboxyl group-containing copolymerizable monomer is excessively large relative to the main component (meth)acrylic acid alkyl ester, the effective period becomes too short and cross-linking is performed before coating. Therefore, coating is impossible.

The surface protective film of Comparative Example 3 may be due to a carboxyl group-free copolymerizable monomer, a crosslinking agent, and an antistatic agent, and the HLB value of the polyether modified siloxane compound is too small. The adhesive force at a peeling speed of 0.3 m/min in a low speed region and the peeling speed at a high speed region of 30 m/min were too large, the surface resistivity and the peeling static voltage were high, and the workability and durability were poor.

As described above, in the surface protective films of Comparative Examples 1 to 3, all of the following performance requirements could not be satisfied at the same time: (1) the balance of the adhesive force at the peeling speed of the low-speed region and the high-speed region was obtained; (2) the adhesion was prevented. The occurrence of agent residues; (3) excellent antistatic properties; and (4) reworkability.

Claims (8)

An adhesive composition comprising an antistatic agent-containing adhesive composition comprising an acrylic polymer having an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms as a main component And containing 85 to 98.5 parts by weight of the main component, that is, alkyl (meth)acrylate, 0.1 to 15 parts by weight of a hydroxyl group-containing copolymerizable monomer, and 0.1 to 100 parts by weight of the acrylic polymer. 2 parts by weight of a carboxyl group-containing copolymerizable monomer and 0.1 to 5 parts by weight of a crosslinking agent, the acrylic polymer having an acid value of 0.01 to 8.0, and the antistatic agent being an ionic compound having a melting point of 30 to 50 ° C Further, the adhesive composition contains a polyether modified siloxane compound. The adhesive composition of claim 1, wherein the main component, alkyl (meth)acrylate, is selected from the group consisting of butyl (meth)acrylate and isobutyl (meth)acrylate, Amyl methacrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyl methacrylate One or more of the group consisting of esters, decyl (meth)acrylate, isodecyl (meth)acrylate, and decyl (meth)acrylate. The adhesive composition according to claim 1 or 2, wherein the hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate and 6-hydroxyl (meth)acrylate. Hexyl ester, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N At least one or more of the group consisting of -hydroxyethyl(meth)acrylamide. The adhesive composition according to any one of claims 1 to 3, wherein the carboxyl group-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyethyl (meth)acrylate, Carboxymethyl (meth)acrylate, 2-(meth)acryloxyethylhexahydrophthalic acid, 2-(methyl)propenyloxypropylhexahydrophthalic acid, 2-( Methyl) propylene methoxyethyl phthalate, 2-(methyl) propylene methoxyethyl succinic acid, 2-(methyl) propylene methoxyethyl maleic acid, carboxy polycaprolactone One or more of the group consisting of mono(meth)acrylate and 2-(meth)acryloxyethyltetrahydrophthalic acid. The adhesive composition according to any one of claims 1 to 4, wherein the polyether modified siloxane compound is a polyether modified siloxane compound having an HLB value of 7 to 12. An adhesive composition according to any one of claims 1 to 5, wherein the The crosslinking agent is a trifunctional or higher isocyanate compound. An adhesive film formed by forming an adhesive layer on one or both sides of a resin film, the adhesive layer being obtained by crosslinking an adhesive composition according to any one of claims 1 to 6. . A surface protective film obtained by forming an adhesive layer on one side of a resin film, which is obtained by crosslinking an adhesive composition according to any one of claims 1 to 6.