TWI491691B - Adhesive composition and surface protection film - Google Patents

Description

Adhesive composition and surface protective film

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 or a retardation film which constitutes a liquid crystal display, and which protects the surface of an optical member such as a polarizing plate or a retardation film. And a surface protective film using the same.

In the manufacturing steps of an optical member such as a polarizing plate or a phase difference plate constituting a liquid crystal display, the surface protective film is temporarily adhered to the surface of the optical member. When the optical member is assembled in the liquid crystal display, the surface protective film is peeled off from the optical member and removed. The surface protective film for protecting the surface of the optical member is generally referred to as a step film since it is used only in the manufacturing step.

The surface protective film used in the step of producing the optical member is formed on one surface of an optically transparent polyethylene terephthalate (PET) resin film to form an adhesive layer. Further, the release-treated release film for protecting the adhesive layer is adhered to the upper surface of the adhesive layer until it is adhered to the optical member.

In addition, an optical member such as a polarizing plate or a retardation film is subjected to optical evaluation of the display capability, chromaticity, contrast, and impurity incorporation of the liquid crystal display panel in a state in which the surface protective film is adhered. Inspection, therefore, the necessary properties of the surface protective film are that no bubbles or impurities adhere to the adhesive layer.

Further, in recent years, it is necessary to prevent the antistatic property of generating static electricity when the surface protective film is peeled off from an optical member such as a polarizing plate or a phase difference plate. The reason for this is that when the adhesive layer is peeled off from the adherend, there is a possibility that the electrification at the time of peeling due to the generated static electricity may cause the electrical control circuit of the liquid crystal display to malfunction.

In addition, when the surface protective film is adhered to an optical member such as a polarizing plate or a retardation plate, the surface protective film may be temporarily peeled off and the surface protective film may be reattached for various reasons. At this time, a surface protective film which is easily peeled off from the optical member of the adherend (having reworkability) is required.

Further, when the surface protective film is peeled off from an optical member such as a polarizing plate or a phase difference plate, it is required to be able to be quickly peeled off. That is, in order to perform peeling quickly even by peeling at a high speed, it is required that the adhesive force is less affected by the peeling speed.

As described above, in recent years, the performances of the following (1) to (4) are required as the required performance of the adhesive layer constituting the surface protective film.

(1) Under low-speed peeling and high-speed peeling, a balance of adhesion is obtained.

(2) It can prevent the occurrence of adhesive residue.

(3) It has excellent antistatic properties.

(4) Has rework performance.

However, although the required performance of each of (1) to (4) can be satisfied, it is still extremely difficult to have all of the required performances of (1) to (4) required for the adhesive layer of the surface protective film.

For example, the following proposals are known regarding (1) obtaining a balance of adhesion under low-speed peeling and high-speed peeling; and (2) preventing occurrence of adhesive residue.

An acrylic resin obtained by crosslinking a copolymer of an alkyl (meth)acrylate having a carbon number of 7 or less and a copolymerizable compound having a carboxyl group as a main component and crosslinking the mixture by a crosslinking agent The adhesive is a problem that the adhesive adheres to the side of the adherend after a long time of sticking, and the adhesive force of the adherend rises with time. In order to prevent this problem, an adhesive (pressure-sensitive adhesive) is known which uses an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms and a copolymerizable compound having an alcoholic hydroxyl group. The copolymer is obtained by crosslinking treatment with a crosslinking agent (Patent Document 1).

Further, an adhesive or the like is proposed, and a copolymer of a (meth)acrylic acid alkyl ester and a carboxyl group-containing copolymerizable compound is blended in a small amount in the same copolymer as described above, and a crosslinking agent is used for crosslinking treatment. . However, when it is used for surface protection of a plastic plate having a low surface tension and a smooth surface, there is a problem of peeling due to lifting during processing or storage, or high-speed peeling by manual peeling. The problem of poor peelability.

In order to solve such problems, an adhesive composition is proposed which is based on (a) an alkyl (meth) acrylate having an alkyl (meth) acrylate having an alkyl group having 8 to 10 carbon atoms as a main component. 100 parts by weight of the base ester is prepared by adding (b) 1 to 15 parts by weight of a carboxyl group-containing copolymerizable compound and 3 to 100 parts by weight of (c) a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms. a copolymer of a monomer mixture and compounding the carboxyl group relative to the above component (b) in the copolymer A crosslinking agent or more (Patent Document 2).

The adhesive composition described in Patent Document 2 does not have a peeling phenomenon such as floating during processing or storage, and the adhesion time rises little, and the releasability is excellent, even after long-term storage, special It is a long-term storage in a high-temperature environment, and can be further peeled off with a small force. At this time, no adhesive residue is generated on the adherend, and re-peeling can be performed with a small force even when high-speed peeling is performed.

In addition, (3) has a rework property, for example, an adhesive composition is proposed, which is a curing agent for dissolving an isocyanate compound in an acrylic resin in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of the acrylic resin. A phthalate oligomer (Patent Document 3).

In Patent Document 3, an alkyl acrylate having an alkyl group having a carbon number of about 2 to 12, an alkyl methacrylate having an alkyl group having a carbon number of about 4 to 12, or the like is a main monomer component. For example, a monomer component containing another functional group such as a carboxyl group-containing monomer may be contained. In general, it is preferable to contain 50% by weight or more of the above-mentioned main monomer, and 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% by weight. %. The adhesive composition described in Patent Document 3 has a small effect on the cohesive force and the adhesive force over a high temperature or a high temperature and high humidity, and exhibits an excellent effect on the curved surface adhesion force, so that it has reworkability.

In general, if the adhesive layer is made into a flexible property, adhesive residue is likely to occur, and reworkability is also likely to be lowered. That is, when it is stuck incorrectly, It is difficult to peel off and it is difficult to re-stick. Therefore, it is necessary to crosslink the monomer having a functional group such as a carboxyl group to the main agent, and to form the adhesive layer with a certain hardness so as to have reworkability.

[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 8-199130

In the prior art, as a required performance for the adhesive layer constituting the surface protective film, it is required to obtain a balance of adhesion, excellent antistatic property, and reworkability under low-speed peeling and high-speed peeling. However, although it is possible to individually satisfy the individual required performance, it is still impossible to satisfy all the required performances required for the adhesive layer of the surface protective film.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide an adhesive composition and a surface protective film which are excellent in balance of adhesion under low-speed peeling and high-speed peeling, and are excellent in durability and reworkability.

In order to solve the above problems, the present invention provides an adhesive composition comprising (A) a (meth) acrylate monomer having an alkyl group having C4 to C10, (B) a hydroxy group-containing copolymerizable monomer, (C) a copolymer of a carboxyl group-containing copolymerizable monomer and (D) a polyalkylene glycol mono(meth)acrylate monomer, and further containing (E) a trifunctional or higher isocyanate compound, (F) Cross-linking inhibitor, (G) Crosslinking catalyst, (H) polyether modified siloxane compound.

The (B) hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and (methyl). a compound consisting of 2-hydroxyethyl acrylate, N-hydroxy(meth) acrylamide, N-methylol (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide At least one or more; preferably, the (A) (C)-containing (meth) acrylate monomer having a C4 to C10 alkyl group having 0.1 to 5.0 parts by weight of the above (B) hydroxyl group; Copolymerizable monomer, and (B) hydroxyl group-containing copolymerizable monomer, 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, (meth)acrylic acid 4- The total amount of hydroxybutyl ester is 0 to 0.9 parts by weight.

The (C) carboxyl group-containing copolymerizable monomer is at least one selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. It is preferred to contain 0.35 to 1.0 part by weight of the above (C) carboxyl group-containing copolymerizable monomer with respect to 100 parts by weight of the (A) alkyl group having a C4 to C10 (meth) acrylate monomer. body.

The (D) polyalkylene glycol mono(meth)acrylate monomer is selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxylated polymer. At least one or more of the compound group consisting of alkanediol (meth) acrylate; preferably a (meth) acrylate having a C4 to C10 carbon number with respect to 100 parts by weight of the above (A) alkyl group The monomer contains 1 to 20 parts by weight of the above (D) polyalkylene glycol mono(meth)acrylate monomer.

The above (E) trifunctional or higher isocyanate compound is an addition member of a trimer isocyanate selected from a hexamethylene diisocyanate compound, a isocyanurate of an isophorone diisocyanate compound, and a hexamethylene diisocyanate compound. At least one or more of a compound composition of an isophorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, and a biuret compound of an isophorone diisocyanate compound, It is preferable to contain 0.5 to 5.0 parts by weight of the above (E) trifunctional or higher isocyanate compound per 100 parts by weight of the above copolymer.

The (H) polyether-modified oxime compound is a polyether-modified oxirane compound having an HLB value of 7 to 12, preferably 0.01 to 0.5 part by weight based on 100 parts by weight of the above copolymer. The above (H) polyether modified oxirane compound.

The above (F) crosslinking inhibitor-based ketoenol tautomer compound preferably contains 1.0 to 5.0 parts by weight of the above (F) crosslinking inhibitor with respect to 100 parts by weight of the above copolymer.

The (G) cross-linking catalyst organotin compound preferably contains 0.01 to 0.5 part by weight of the above (G) cross-linking catalyst based on 100 parts by weight of the copolymer.

Preferably, the adhesive layer obtained by crosslinking the above-mentioned adhesive composition has an adhesive force of 0.3 to 0.1 N/25 mm at a low-speed peeling region of 0.3 m/min, and an adhesive force of 1.0 N at a high-speed peeling region of 30 m/min. /25mm or less.

Moreover, the present invention provides an adhesive film which will make the above adhesive composition The adhesive layer formed by crosslinking is formed on one surface or both surfaces of the resin film.

Furthermore, the present invention provides a surface protective film obtained by forming an adhesive layer obtained by crosslinking the above-mentioned adhesive composition on one surface of a resin film, and is characterized in that the adhesive layer is formed through the adhesive layer. After the surface protection film was drawn by a steel ball pen, no contamination of the adherend occurred.

The above surface protective film can be used as a surface protective film of a polarizing plate.

It is preferable to carry out antistatic and anti-pollution treatment on the surface of the above-mentioned resin film opposite to the side on which the above-mentioned adhesive layer is formed.

According to the present invention, it is possible to satisfy all the properties required for the adhesive layer of the surface protective film which have not been solved by the prior art. In addition, superior performance against the occurrence of residual glue is obtained. Specifically, the performance of preventing the occurrence of residual glue can be further improved.

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

The adhesive composition of the present invention is characterized in that the main component is a (meth) acrylate monomer having (A) an alkyl group having a C4 to C10 carbon number, and (B) a hydroxy group-containing copolymerizable monomer. And (C) a copolymer of a carboxyl group-containing copolymerizable monomer and (D) a polyalkylene glycol mono(meth)acrylate monomer, and further containing (E) a trifunctional or higher isocyanate compound, (F) a crosslinking inhibitor, (G) a crosslinking catalyst, and (H) a polyether-modified oxirane compound.

Examples of the (meth) acrylate monomer having (A) an alkyl group having a carbon number of C4 to C10 include butyl (meth) acrylate, isobutyl (meth) acrylate, and amyl (meth) acrylate. , (meth) hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (methyl) Ethyl acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, and the like.

Examples of the (B) hydroxyl group-containing copolymerizable monomer include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl A (hydroxy)-containing (meth) acrylamide such as acrylamide or the like.

Preferably, it is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N At least one or more of a group consisting of hydroxy (meth) acrylamide, N-methylol (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide.

It is preferable to contain 0.1 to 5.0 parts by weight of the above (B) hydroxyl group-containing copolymerizable monomer with respect to 100 parts by weight of the (A) (C)-C10-C10 (meth) acrylate monomer. .

Further, among (B) a hydroxyl group-containing copolymerizable monomer, 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxyl (meth)acrylate The total amount of the butyl ester is preferably less than 1 part by weight (may not be contained), more preferably 0 to 0.9 part by weight.

Preferably, the (C) carboxyl group-containing copolymerizable monomer is at least one selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth) acrylate, and carboxypentyl (meth) acrylate. the above.

It is preferable to contain 0.35 to 1.0 part by weight of (C) a carboxyl group-containing copolymerizable monomer with respect to 100 parts by weight of the (A) alkyl group having a C4 to C10 (meth) acrylate monomer.

The (D) polyalkylene glycol mono(meth)acrylate monomer may be a compound in which one of the plurality of hydroxyl groups of the polyalkylene glycol is esterified to a (meth)acrylate. Since the (meth) acrylate group becomes a polymerizable group, it can be copolymerized to the main agent polymer. The other hydroxyl group may be maintained as OH, or may be an alkyl ether such as methyl ether or diethyl ether or a saturated carboxylic acid ester such as acetate.

The alkylene group which the polyalkylene glycol has may be, for example, an ethyl group, a propyl group or a butyl 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 the polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene glycol. Alternatively, the copolymer may be a block copolymer or a random copolymer.

The (D) polyalkylene glycol mono(meth)acrylate monomer is preferably selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and B. In a group of compounds consisting of oxypolyalkylene glycol (meth) acrylates At least one or more.

More specifically, for example, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, polyethylene glycol-poly Propylene glycol-mono(meth)acrylate, polyethylene glycol-polybutylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol-poly Propylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol-(meth)acrylate, methoxypolybutylene glycol -(Meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, methoxy Poly-propylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate; ethoxylated polyethylene glycol-( Methyl) acrylate, ethoxypolypropylene glycol-(meth) acrylate, ethoxylated polybutylene glycol-(meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol-(methyl) Acrylate, ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate Ethoxy - glycol - polyethylene glycol - (meth) acrylate, ethoxy - polyethylene glycol - polypropylene glycol - polyethylene glycol - (meth) acrylate.

It is preferred to contain 1 to 20 parts by weight of the above (D) polyalkylene glycol monomer with respect to 100 parts by weight of the (A) alkyl group having a C4 to C10 (meth) acrylate monomer. Methyl) acrylate monomer.

The (E) trifunctional or higher isocyanate compound is a polyisocyanate compound having at least three or more isocyanate (NCO) groups in one molecule. For example, diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and dylyl diisocyanate may be mentioned (in one molecule) a biuret modified body or a trimerized isocyanate modified product having two NCO groups; a trivalent or higher polyhydric alcohol such as trimethylolpropane or glycerin (having at least three or more OH groups in one molecule) Addition of a compound) (polyol modified body) or the like.

(E) The trifunctional or higher isocyanate compound is a polyisocyanate compound having at least three or more isocyanate (NCO) groups in one molecule, and particularly preferably a trimeric isocyanate selected from a hexamethylene diisocyanate compound, and isophor. A trimeric isocyanate of a keto diisocyanate compound, an addition object of a hexamethylene diisocyanate compound, an addition object of an isophorone diisocyanate compound, a biuret body of a hexamethylene diisocyanate compound, and an isophor At least one or more of the compound groups consisting of biuret bodies of the keto diisocyanate compound. The (E) trifunctional or higher isocyanate compound is preferably contained in an amount of 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

Examples of the (F) crosslinking inhibitor include methyl ethyl acetate, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, and stearyl acetate. A β-ketoester such as an ester, or a β-diketone such as acetamidineacetone, 2,4-hexanedione or benzamidineacetone. These are ketoenol tautomer compounds, and in the adhesive composition using a polyisocyanate compound as a crosslinking agent, by fixing the isocyanate group which the crosslinking agent has, it is possible to suppress the adhesive agent after the crosslinking agent is blended. Excessive viscosity of the composition rises or gels, prolongs the composition of the adhesive Storage period.

(F) The crosslinking inhibitor is preferably a ketoenol tautomer compound, and particularly preferably at least one selected from the group consisting of ethyl acetate and ethyl acetate.

It is preferred to contain 1.0 to 5.0 parts by weight of (F) a crosslinking inhibitor with respect to 100 parts by weight of the copolymer.

In the case where the polyisocyanate compound is used as the crosslinking agent, the (G) crosslinking catalyst may have a function as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent, and for example, An organometallic compound such as an amine compound such as a tertiary amine, an organotin compound, an organic lead compound or an organozinc compound.

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

Examples of the organotin compound include a dialkyl tin oxide, a fatty acid salt of a dialkyl tin, a fatty acid salt of stannous, and the like.

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

It is preferred to contain 0.01 to 0.5 part by weight of the (G) crosslinking catalyst with respect to 100 parts by weight of the copolymer.

(H) Polyether-modified oxirane compound is a polyether-based oxirane compound, in addition to the usual oxirane unit (-SiR ¹ ₂ -O-), Oxysilane unit (-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 kinds of alkylene groups, and R ⁴ represents one or two or more kinds of alkyl groups and hydrazines. Base or the like (end group). The polyether group may, for example, be a polyoxyalkylene group such as a polyoxyalkylene group ((C ₂ H ₄ O) _n ) or a polyoxylated propyl group ((C ₃ H ₆ O) _n ).

(H) a polyether-modified siloxane compound is a polyether-modified oxirane compound having an HLB value of 7 to 12, preferably 0.01 to 0.5 part by weight based on 100 parts by weight of the above copolymer. The above (H) polyether modified oxirane compound. More preferably, it is 0.1 to 0.5 part by weight.

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

The polyether-modified oxane compound is, for example, a polyorganosiloxane chain having a decyl group, and an organic compound having an unsaturated bond and a polyoxyalkylene group is grafted by a hydroquinone reaction. . Specifically, for example, dimethyloxane. Methyl (polyoxyethylene) alkane copolymer, dimethyl methoxyalkyl methyl (polyoxyethylene) decane. Methyl (polyoxypropylene) siloxane copolymer, dimethyl methoxy alkane. A methyl (polyoxypropylene) siloxane copolymer or the like.

The adhesion and reworkability of the adhesive can be improved by blending the (H) polyether modified siloxane compound into the adhesive composition.

Further, as another component, a copolymerizable (meth)acrylic monomer containing an alkylene oxide, a (meth)acrylamide monomer, and a dialkyl substitution can be appropriately formulated. Known additives such as acrylamide monomers, surfactants, hardening accelerators, plasticizers, fillers, hardening inhibitors, processing aids, anti-aging agents, antioxidants, antistatic agents, and the like. These may be used alone or in combination of two or more.

As an antistatic agent, an ionic compound is mentioned, for example. Further, antistatic properties can be imparted by copolymerizing an ionic acrylic monomer into a copolymer of a main component.

The copolymer of the main component used in the adhesive composition of the present invention can be copolymerized by (A) a (meth) acrylate monomer having an alkyl group having a carbon number of C4 to C10 and (B) a hydroxyl group-containing copolymer. The monomer, (C) a carboxyl group-containing copolymerizable monomer, and (D) a polyalkylene glycol mono(meth)acrylate monomer are polymerized and synthesized. The polymerization method of the copolymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.

In the above copolymer, (E) a trifunctional or higher isocyanate compound, (F) a crosslinking inhibitor, (G) a crosslinking catalyst, a (H) polyether-modified a pyrithion compound, and any appropriate The additive of the present invention can prepare the adhesive composition of the present invention.

Preferably, the adhesive layer obtained by crosslinking the above adhesive composition has an adhesive force of 0.3 to 0.1 N/25 mm at a low-speed peeling region of 0.3 m/min, and an adhesive force of 1.0 N/min at a high-speed peeling region of 30 m/min. 25mm or less. As a result, it is possible to obtain a performance in which the adhesive force has little change with the peeling speed, and even if it is peeled at a high speed, peeling can be performed quickly. Further, in order to re-stick, the surface protective film is temporarily peeled off, and an excessive force is not required, and it is easy to peel off from the adherend.

The gel fraction of the adhesive layer (adhesive after crosslinking) obtained by crosslinking the adhesive composition of the present invention is preferably 95 to 100%. Thus, since the gel fraction is high, the adhesion in the low-speed peeling region can be prevented from becoming excessive, the dissolution of the unpolymerized monomer or oligomer from the copolymer is lowered, and the reworkability and high temperature are improved. Durability in high humidity, inhibiting contamination by adherends.

The adhesive film of the present invention is formed by forming an adhesive layer obtained by crosslinking the adhesive composition of the present invention on one surface or both surfaces of a resin film. Further, the surface protective film of the present invention is a surface protective film in which an adhesive layer obtained by crosslinking the adhesive composition of the present invention is formed on one surface of a resin film. In the adhesive composition of the present invention, since the components (A) to (H) are blended in a well-balanced manner, the balance of the adhesive force is excellent in the low-speed peeling region and the high-speed peeling region, and durability and reworkability ( It is also excellent in that migration by a steel ballpoint pen on the surface protective film via the above-mentioned adhesive layer does not cause contamination of the adherend. Therefore, the surface protective film of the present invention can be used as a surface protective film of a polarizing plate.

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

In the base film, antifouling treatment by an fluorenone-based, fluorine-based release agent, coating agent, cerium oxide fine particles or the like can be performed on the surface of the resin film opposite to the side on which the adhesive layer layer is formed. Antistatic treatment by application or kneading of an antistatic agent.

In the release film, a release treatment by an anthrone or a fluorine-based release agent is applied to the surface of the pressure-sensitive adhesive layer on the side to which the adhesive surface is adhered.

[Examples]

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

<Preparation of acrylic acid copolymer> [Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen. Then, 100 parts by weight of 2-ethylhexyl acrylate, 0.9 parts by weight of 8-hydroxyoctyl acrylate, 0.5 parts by weight of acrylic acid, 3 parts by weight of polyethylene glycol monoacrylate, and a solvent (ethyl acetate) were added to the reaction apparatus. 60 copies. 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 copolymer solution used in Example 1 having a weight average molecular weight of 500,000. 1.

[Examples 2 to 9 and Comparative Examples 1 to 9]

The examples 2 to 9 were obtained in the same manner as in the acrylic copolymer solution 1 used in the above Example 1, except that the composition of the monomers was as described in Tables 1 (A) to (D), respectively. The acrylic copolymer solution used in Comparative Examples 1 to 9.

<Preparation of Adhesive Composition and Surface Protective Film> [Example 1]

As described above, for the produced acrylic copolymer solution 1 (in which the acrylic copolymer was 100 parts by weight), 0.1 part by weight of KF-351A (polyether modified oxirane compound of HLB=12), acetonitrile acetone 2.5 was added. After the parts by weight and stirred, 1.5 parts by weight of CORONATE HX (trimeric isocyanate of hexamethylene diisocyanate compound) and 0.02 parts by weight of dioctyltin dilaurate were added and stirred to obtain an adhesive composition of Example 1. The adhesive composition was applied onto a release film composed of an oxime resin coated polyethylene terephthalate (PET) film, and then dried at 90 ° C to remove the solvent to obtain an adhesive layer. Adhesive sheet having a thickness of 25 μm.

Then, the adhesive sheet is transferred to the opposite surface of the antistatic and antifouling treatment of the antistatic and antifouling treated polyethylene terephthalate (PET) film on one side, and The surface protective film of Example 1 having a laminated structure of a PET film/adhesive layer/release film (PET film coated with an oxime resin) which is antistatic and antifouling treatment.

[Examples 2 to 9 and Comparative Examples 1 to 9]

Except that the composition of the additive was as described in (E) to (H) of Table 1, the same manner as in the surface protective film of Example 1 was carried out, and Examples 2 to 9 and Comparative Examples 1 to 9 were obtained. Surface protection film.

In Table 1, the blending ratio of each component is a numerical value obtained by adding 100 parts by weight of the total of the group (A), and is represented by a bracket. Further, the compound names of the respective components used in Table 1 are shown in Table 2. In addition, CORONATE (registered trademark) HX and HL are trade names of Japan POLYURETHANE INDUSTRIAL CO., LTD.; TAKENATE (registered trademark) D-140N is the trade name of Mitsui Chemicals Co., Ltd.; DURANATE (registered trademark) 24A-100 is Asahi Kasei Chemicals The trade name of the company limited by shares; 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>

The surface protective films of Examples 1 to 9 and Comparative Examples 1 to 9 were aged for 7 days in an environment of 23° C. and 50% RH, and then the release film (PET film coated with an anthrone resin) was peeled off to expose the adhesion. The agent layer was used as a measurement sample of the gel fraction.

Further, the surface protective film exposing the adhesive layer is adhered to the surface of the polarizing plate adhered to the liquid crystal cell via the adhesive layer, and left for 1 day, and then subjected to autoclaving at 50 ° C, 5 atm, and 20 minutes. Further 12 small at room temperature In this case, it is used as a measurement sample for adhesion and durability.

<gel fraction>

After the aging was completed, the mass of the measurement sample before sticking to the polarizing plate was accurately measured, and after immersing in toluene for 24 hours, it was filtered by a metal mesh of 200 mesh. Then, after drying the filtrate at 100 ° C for 1 hour, the mass of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive after crosslinking) was calculated from the following formula.

Gel fraction (%) = insoluble portion (g) / adhesive quality (g) × 100

<adhesion>

The following peel strength was used as the adhesive force: the test sample obtained above was peeled off at a low speed (0.3 m/min) and a high speed (30 m/min) in the direction of 180° using a tensile tester (25 mm adhered to the surface of the polarizing plate) Peel strength measured by a wide surface protection film).

<reworkability>

After drawing on the surface protective film of the measurement sample obtained above by a steel ball pen (loading 500 g, reciprocating three times), the surface protective film was peeled off from the polarizing plate, and the surface of the polarizing plate was observed, and the presence or absence of contamination of the polarizing plate was confirmed. The evaluation target is based on the case where the polarizing plate is not polluted, and is set to "○". When the contamination is traced along at least a part of the trajectory drawn by the ballpoint pen, it is evaluated as "△", and the trajectory drawn along the ballpoint pen is evaluated. It was confirmed that the contamination was transferred, and the adhesion of the adhesive was confirmed from the surface of the adhesive to be "x".

<Durability>

The measurement sample obtained above was placed in an environment of 60 ° C and 90% RH for 250 hours, and then taken out at room temperature. After further standing for 12 hours, the adhesion was measured, and it was confirmed that it was not significantly different from the initial adhesion. increase. The evaluation target standard was evaluated as "○" when the adhesion after the test was 1.5 times or less of the initial adhesive force, and "x" when the adhesion was more than 1.5 times.

The evaluation results are shown in Table 3.

The surface protective films of Examples 1 to 9 had an adhesive force of 0.3 to 0.1 N/25 mm at a low-speed peeling region of 0.3 m/min, and an adhesive force of 30 nm/min at a high-speed peeling region of 1.0 N/25 mm or less, and were passed by a steel ball pen. The adhesive layer was not traced to the adherend after being drawn on the surface protective film, and the durability was excellent when placed at 60 ° C and 90% RH for 250 hours.

That is, at the same time, (1) peeling at a low speed and peeling at a high speed are obtained. The balance of adhesion, (2) can prevent the occurrence of adhesive residue, and (3) all the required performance of rework performance.

The surface protective film of Comparative Example 1 may have a low adhesion at a low-speed peeling region of 0.3 m/min and a slight reworkability because it does not contain (D) a polyalkylene glycol mono(meth)acrylate monomer.

In the surface protective film of Comparative Example 2, (B) the hydroxyl group-containing monomer is too small, (D) the polyalkylene glycol mono(meth)acrylate monomer is too small, (E) the isocyanate compound is excessive, and (H) is aggregated. The HLB value of the ether-modified oxirane compound is too small, so the adhesion at a low-speed peeling region of 0.3 m/min and the adhesion at a high-speed peeling region of 30 m/min become excessive, reworkability and durability are deteriorated, and gel fraction Go low.

In the surface protective film of Comparative Example 3, (B) the monomer having a hydroxyl group is excessive, (C) the acid-containing monomer is excessive, and (D) the polyalkylene glycol mono(meth)acrylate monomer is excessive (H). The polyether-modified helioxane compound has an excessively large HLB value, so that the adhesion at a low-speed peeling region of 0.3 m/min is low and durability is poor.

In the surface protective film of Comparative Example 4, since (C) the acid-containing monomer was too small and the (D) polyalkylene glycol mono(meth)acrylate monomer was not contained, the adhesion at a low-speed peeling region of 0.3 m/min was possible. Low force, poor rework and durability.

In the surface protective film of Comparative Example 5, there may be a case where (B) a monomer having a hydroxyl group is excessive, (D) a polyalkylene glycol mono(meth)acrylate monomer is too small, and (E) an isocyanate compound is too small, so that a low-speed peeling region may be used. Adhesion of 0.3m/min and adhesion of 30m/min in high-speed peeling area become excessive, reworkability and durability The variation is poor and the gel fraction is low.

In the surface protective film of Comparative Example 6, since the (F) crosslinking inhibitor and the (G) crosslinking catalyst were excessively mixed, the storage period was too short, and crosslinking was performed before coating, and coating was impossible.

The surface protective film of Comparative Example 7 may contain too much MA having a C1 alkyl group in (A) a (meth) acrylate monomer having an alkyl group, (B) a monomer having a hydroxyl group, and no (D) poly Alkanediol mono(meth)acrylate monomer, unmixed (G) cross-linking catalyst, so the adhesion of 0.3m/min in the low-speed peeling area and the adhesion of 30m/min in the high-speed peeling area are too large, reworkability and durability Poor sex.

In the surface protective film of Comparative Example 8, there may be a case where the (D) polyalkylene glycol mono(meth)acrylate monomer is excessive and the (H) polyether modified naphthene compound is not formulated, so the low-speed peeling region is 0.3 m. The adhesion of /min and the high-speed peeling area of 30m/min have too much adhesion and poor reworkability.

In the surface protective film of Comparative Example 9, there may be a case where the (D) polyalkylene glycol mono(meth)acrylate monomer and the (H) polyether modified polyoxane compound are excessive, so the low-speed peeling region is 0.3 m. /min has low adhesion, poor reworkability and poor durability.

As described above, in the surface protective films of Comparative Examples 1 to 9, it is impossible to simultaneously satisfy (1) the adhesion balance in the low-speed peeling and the high-speed peeling, (2) the prevention of the occurrence of the adhesive residue, and (3) the reworkability. All the required performance.

Claims (14)

An adhesive composition comprising (A) a (meth) acrylate monomer having an alkyl group having C4 to C10, (B) a hydroxy group-containing copolymerizable monomer, and (C) a carboxyl group-containing copolymerizable group a monomer and a copolymer of (D) a polyalkylene glycol mono(meth)acrylate monomer, and further containing (E) a trifunctional or higher isocyanate compound, (F) a crosslinking inhibitor, (G) a cross-linking catalyst, (H) polyether-modified oxoxane compound; respectively, containing 0.1 part by weight of the (A) alkyl (C)-C10 (meth) acrylate monomer having C4 to C10; ~5.0 parts by weight of the above (B) hydroxyl group-containing copolymerizable monomer, 0.35 to 1.0 part by weight of the above (C) carboxyl group-containing copolymerizable monomer, and 1 to 20 parts by weight of the above (D) polyalkylene glycol single The (meth) acrylate monomer contains 0.5 to 5.0 parts by weight of the above (E) trifunctional or higher isocyanate compound per 100 parts by weight of the copolymer. The adhesive composition of claim 1, wherein the (B) hydroxyl group-containing copolymerizable single system is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. , 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyl At least one or more of a compound group consisting of ethyl (meth) acrylamide; (B) a hydroxyl group-containing copolymerizable monomer, (meth)acrylic acid 8-hydroxyoctyl ester, (meth)acrylic acid 6 The total amount of at least one of -hydroxyhexyl ester and 4-hydroxybutyl (meth)acrylate is 0 to 0.9 parts by weight. The adhesive composition according to claim 1 or 2, wherein the (C) carboxyl group-containing copolymerizable single system is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth) acrylate, and carboxypentyl group. At least one or more of the compound groups consisting of (meth) acrylate. An adhesive composition according to claim 1 or 2, wherein the (D) polyalkylene glycol mono(meth)acrylate single system is selected from the group consisting of polyalkylene glycol mono(meth)acrylates, At least one or more of the compound group consisting of oxypolyalkylene glycol (meth) acrylate and ethoxylated polyalkylene glycol (meth) acrylate. The adhesive composition according to claim 1 or 2, wherein the (E) trifunctional or higher isocyanate compound is selected from the group consisting of a trimer isocyanate of a hexamethylene diisocyanate compound and an isophorone diisocyanate compound. Addition of trimeric isocyanate, hexamethylene diisocyanate compound, addition of isophorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, isophorone diisocyanate compound At least one or more of the compound groups consisting of biuret bodies. The adhesive composition according to claim 1 or 2, wherein the (H) polyether modified siloxane compound is a polyether modified oxirane compound having an HLB value of 7 to 12; The (H) polyether-modified oxime compound is contained in an amount of 0.01 to 0.5 part by weight based on 100 parts by weight of the above copolymer. An adhesive composition according to claim 1 or 2, wherein the (F) crosslinking inhibitor is a ketoenol tautomer compound, 1.0 to 5.0 parts by weight of the above (F) crosslinking inhibitor is contained with respect to 100 parts by weight of the above copolymer. The adhesive composition according to claim 1 or 2, wherein the (G) cross-linking catalyst organotin compound contains 0.01 to 0.5 part by weight of the above (G) with respect to 100 parts by weight of the copolymer. ) Cross-linking catalyst. The adhesive composition according to claim 1 or 2, wherein the adhesive layer obtained by crosslinking the adhesive composition has an adhesive force of 0.3 to 0.1 N/25 mm at a low-speed peeling region of 0.3 m/min. The adhesive force at a high-speed peeling region of 30 m/min was 1.0 N/25 mm or less. An adhesive film obtained by crosslinking an adhesive composition of the first or second aspect of the patent application is formed on one side or both sides of a resin film. A surface protective film which is obtained by crosslinking an adhesive composition of the first or second aspect of the patent application, which is formed on one side of a resin film, and is applied to the surface protective film via the above adhesive layer. After the drawing with the steel ball pen, no contamination of the adherend occurred. The surface protective film of claim 11 is used as a surface protective film for a polarizing plate. The surface protective film according to claim 11, wherein the antistatic and antifouling treatment is performed on a surface of the resin film opposite to the side on which the adhesive layer is formed. The surface protection film of claim 12, wherein the antistatic and antifouling treatment is performed on a surface of the resin film opposite to the side on which the adhesive layer is formed.