KR20130093016A - Adhesive composition, adhesive film and surface-protective adhesive film - Google Patents

Abstract

PURPOSE: An adhesive composition and an adhesive film are provided to have an excellent electrification preventing function, an anti-corrosion to adhered object, and low contamination. CONSTITUTION: An adhesive composition comprises: (meth) acrylic polymer whose main component is (meth) acrylic acid ester monomer having C1-14 of alkyl group carbon number; and an ionic compound whose melting point is over 30 deg. C, or an ionic compound whose melting point is over 30 deg. C and acid value of (meth)acrylic polymer is under 30. The (meth)acrylic polymer comprises (meth)acrylic monomer having hydroxyl group. An adhesive film is made by forming the adhesive layer formed by cross-linking the adhesive composition on one or both side of a resin film.

Description

Adhesive composition, adhesive film, and surface protection film {ADHESIVE COMPOSITION, ADHESIVE FILM AND SURFACE-PROTECTIVE ADHESIVE FILM}

This invention provides the adhesive composition which has an antistatic performance, the adhesive film which provided the adhesive layer which has antistatic performance on at least one surface of a resin film using this adhesive composition, and a surface protection film. The pressure-sensitive adhesive film and the surface protective film according to the present invention have particularly excellent antistatic performance. For this reason, the surface protection film of this invention can be used for the purpose of protecting the surface of optical films, such as a polarizing plate, a retardation plate, and an antireflection film, in which the plastic film which is easy to generate static electricity is used as a structural member.

Conventionally, in the process of manufacturing optical films, such as a polarizing plate, a retardation plate, and an antireflection film which comprise a liquid crystal display, a surface protection film is temporarily stuck on the surface of an optical film. At the time of attaching the optical film to the liquid crystal display, the surface protective film is peeled off and removed from the optical film. Since the surface protection film for protecting the surface of an optical film is used only for a manufacturing process, it may be called a process film.

As for the surface protection film used at the process of manufacturing an optical film, the adhesive layer is formed in one side of the polyethylene terephthalate (PET) resin film which has optical transparency. Moreover, the peeling process of the peeling process for protecting the adhesive layer is bonded together on an adhesive layer until it bonds to an optical film.

In addition, in the optical films, such as a polarizing plate, a retardation plate, and an antireflection film, in the state which bonded the surface protection film, the product test | inspection with optical evaluation, such as display capability, a hue, contrast, and a foreign material mixing, of a liquid crystal display panel is performed. Therefore, the performance required for a surface protection film is that a bubble and a foreign material do not adhere to an adhesive layer.

Moreover, in recent years, the excellent antistatic performance which prevents generation | occurrence | production of static electricity when peeling a surface protection film from optical films, such as a polarizing plate, a retardation plate, and an antireflection film, is needed. This is because charging at the time of peeling caused by static electricity generated when the adherend peels off the pressure-sensitive adhesive layer may cause the electric control circuit of the liquid crystal display to fail.

Moreover, the adhesive composition which has corrosion resistance which does not generate corrosion even if it bonds optical films, such as a polarizing plate, a retardation plate, and an antireflection film, to a metal adherend, for example, a bezel, etc. is calculated | required.

Moreover, when peeling a surface protection film from optical films, such as a polarizing plate, a retardation plate, and an antireflection film which is a to-be-adhered body, it is desired not to contaminate an to-be-adhered body and to generate | occur | produce so-called adhesive residue.

Thus, in recent years, as a required performance for the pressure-sensitive adhesive layer constituting the surface protection film, (1) having excellent antistatic performance, (2) having corrosion resistance, (3) preventing the occurrence of the adhesive residue The thing etc. are calculated | required from the point of ease of use in using a surface protection film.

However, although each of these (1)-(3) which is a required performance with respect to the adhesive layer which comprises a surface protection film can satisfy individual required performance, it is (1) required for the adhesive layer of a surface protection film. It is very difficult to satisfy all of the required performances of (3) at the same time.

For example, about what has the outstanding antistatic performance, the method of kneading an antistatic agent in a base film as a method for giving antistatic performance to a surface protection film, etc. are disclosed. Examples of the antistatic agent include (a) various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts and primary to tertiary amino groups, (b) sulfonate groups, sulfate ester base groups and phosphoric acid. Anionic antistatic agents having anionic groups such as ester bases and phosphonate groups, (c) amphoteric antistatic agents such as amino acid and amino sulfate esters, and (d) nonionics such as aminoalcohols, glycerins, and polyethylene glycols. Antistatic agent, (e) The polymeric antistatic agent etc. which made high molecular weight of the above antistatic agent are disclosed (patent document 1).

In recent years, it has been proposed to include such an antistatic agent in the base film or directly in the pressure-sensitive adhesive layer without applying it to the surface of the base film.

In addition, the use of an alkali metal salt as a conventional antistatic agent is described in, for example, Patent Literature 2, an alkali metal salt of perchloric acid, an alkaline earth metal salt of perchloric acid, an alkali metal salt of an organic boron complex, as an ionic substance in a (meth) acrylic polymer, And use of one selected from the group consisting of alkaline earth metal salts of organic boron complexes. However, since the adhesive composition containing the antistatic agent which consists of alkali metal salts has metal corrosiveness, corrosion arises when a to-be-adhered body is a metal. For this reason, the adhesive composition which has the outstanding antistatic performance and corrosion resistance is needed.

Moreover, about preventing generation | occurrence | production of an adhesive residue, the adhesive composition which mix | blended the hardening | curing agent of an isocyanate type compound and a specific silicate oligomer with 0.0001-10 weight part with respect to 100 weight part of acrylic resin is proposed, for example in acrylic resin, There is (patent document 3).

In patent document 3, the C2-C12 alkyl acrylate of an alkyl group, the C4-C12 alkyl methacrylate of an alkyl group etc. are made into a main monomer component, For example, it contains other functional groups, such as a carboxyl group-containing monomer. It is said to contain a monomer component. Generally, it is preferable to contain 50 weight% or more of the said main monomer, and content of a functional group containing monomer component is 0.001-50 weight%, Preferably it is 0.001-25 weight%, More preferably, it is 0.01-25 weight % Is said to be preferable. The pressure-sensitive adhesive composition described in Patent Document 3 exhibits a small change in cohesion force and adhesive force over time even under high temperature or high temperature and high humidity, and also exhibits an excellent effect on adhesion to curved surfaces, and does not cause foaming or peeling of the pressure-sensitive adhesive. have.

In general, when the pressure-sensitive adhesive layer is made soft, the pressure-sensitive adhesive residue tends to be generated. That is, when bonding by mistake, peeling is difficult and it becomes difficult to reattach. For this reason, it is necessary for the monomer which has functional groups, such as a carboxyl group, to bridge | crosslink to a main body, and to make an adhesive layer constant hardness, for prevention of generation | occurrence | production of a residual adhesive.

Moreover, the following proposal is known about preventing generation | occurrence | production of an adhesive residue. In an acrylic pressure-sensitive adhesive layer having a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component, which is crosslinked with a crosslinking agent, the adhesive is avoided if a long time passes after bonding. It adheres to a complex side, and the adhesive force with respect to a to-be-adhered body rises with time. In order to solve this problem, the adhesive (pressure sensitive adhesive) which crosslinked this with the crosslinking agent using the copolymer of the (meth) acrylic-acid alkylester which has a C8-C10 alkyl group, and the copolymerizable compound which has an alcoholic hydroxyl group is known ( Patent document 4).

Moreover, the adhesive etc. which mix | blended a small amount of the copolymer of a (meth) acrylic-acid alkylester and a carboxyl group-containing copolymerizable compound with the same copolymer as above, and bridge | crosslinked this with the crosslinking agent are proposed. However, these pressure-sensitive adhesives have a low surface tension, and when used for surface protection of a plastic plate or the like having a smooth surface, a peeling phenomenon such as lifting occurs due to heating during processing or storage.

Japanese Laid-Open Patent Publication No. 11-070629 Japanese Laid-Open Patent Publication 2006-199873 Japanese Unexamined Patent Publication No. 8-199130 Japanese Patent Application Laid-Open No. 63-225677

Alkali metal salts have been used as an antistatic agent to contain in the use which requires the outstanding antistatic performance for the adhesive composition which has the conventional antistatic performance. However, when alkali metal salts are used, corrosion occurs when the adherend is a metal. Moreover, since the conventional surface protection film has the contamination property to a to-be-adhered body, it could not satisfy | fill the required performance calculated | required by the adhesive layer used for a surface protection 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 having excellent antistatic performance, corrosion resistance, and low contamination, an adhesive film and a surface protective film using the same.

Since the adhesive composition in this invention contains an ionic compound whose melting | fusing point is 30 degreeC or more, it has the technical idea to have corrosion resistance and to acquire the outstanding antistatic performance. In addition, by including the (meth) acrylic monomer having a hydroxyl group, a pressure-sensitive adhesive composition with little adhesive residue and low contamination is obtained. By using such an adhesive composition, the adhesive composition which has the outstanding antistatic performance, has corrosion resistance, and is low in pollutability, the adhesive film and surface protection film using the same can be provided.

In order to solve the said subject, this invention is an adhesive composition containing the (meth) acrylic-type polymer whose main component is the (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group WHEREIN: The ionic compound whose melting | fusing point is 30 degreeC or more is It provides an adhesive composition comprising.

Moreover, this invention is an adhesive composition containing the (meth) acrylic-type polymer whose main component is a (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group WHEREIN: The acid value of a (meth) acrylic-type polymer is 30 or less, and melting | fusing point is It provides the pressure-sensitive adhesive composition containing an ionic compound of 30 ° C or more.

It is preferable that the said (meth) acrylic-type polymer contains the (meth) acrylic-type monomer which has a hydroxyl group.

Moreover, this invention provides the adhesive film which formed the adhesive layer which bridge | crosslinked the said adhesive composition in one side or both sides of a resin film.

Moreover, this invention is a surface protection film which formed the adhesive layer which bridge | crosslinked the said adhesive composition in one side of a resin film, after overwriting the surface protection film pasted on the to-be-adhered body via the said adhesive layer with a ballpoint pen, and a to-be-adhered body It peels from, and provides the surface protection film without the migration of the contamination to a to-be-adhered body.

It is preferable to use the said surface protection film as a use of the surface protection film of a polarizing plate. Moreover, it is preferable to perform antistatic and antifouling treatment on the surface opposite to the side which provided the said adhesive layer of the said resin film.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which has the outstanding antistatic performance, has corrosion resistance with respect to a to-be-adhered body, and is low in contamination, an adhesive film and surface protection film using the same can be provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on preferable embodiment.

The pressure-sensitive adhesive composition of the present invention includes a (meth) acrylic polymer having a (meth) acrylic acid ester monomer having an alkyl group of C 1 to C 14 as a main component, and contains an ionic compound having a melting point of 30 ° C. or higher.

Moreover, the adhesive composition of this invention is an adhesive composition containing the (meth) acrylic-type polymer which has the (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group as a main component, The acid value of a (meth) acrylic-type polymer is 30 or less And an ionic compound having a melting point of 30 ° C. or higher.

As a (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) Acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethyl Hexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) Acrylate, tetradecyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. are mentioned. The alkyl group of the alkyl (meth) acrylate monomer may be any of linear, branched or cyclic. It is preferable that the weight ratio with respect to a (meth) acrylic-type polymer of the (meth) acrylic acid ester monomer whose carbon number of an alkyl group is C1-C14 is 50-100%.

It is preferable that a (meth) acrylic-type polymer contains the (meth) acrylic-type monomer which has a hydroxyl group. As a (meth) acrylic-type monomer which has a hydroxyl group, 8-hydroxy octyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy Hydroxyalkyl (meth) acrylates, such as ethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. Hydroxyl group-containing (meth) acrylamides; and the like.

The (meth) acrylic polymer may include a copolymerizable monomer containing a carboxyl group. Examples of the copolymerizable monomer containing a carboxyl group include (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, carboxyethyl (meth) acrylate, and carboxypentyl (meth) acrylate.

Moreover, a (meth) acrylic-type polymer can contain the copolymerizable vinyl monomer of that excepting the above. As another copolymerizable vinyl monomer, in addition to aromatic group containing (meth) acrylic acid esters, such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, styrene, acrylamide, acrylonitrile, methyl vinyl ether, ethyl Various vinyl monomers, such as vinyl ether, vinyl acetate, and a vinyl chloride, are mentioned.

However, when acidic monomers (hereinafter, referred to as acidic monomers), such as monomers containing a carboxyl group, are excessively added, there is a possibility that the corrosiveness is increased by the acid. For this reason, it is preferable that the acid value of a (meth) acrylic-type polymer is 30 or less.

Here, an "acid value" is one of the indicators which show content of an acid, and is represented by the mg number of potassium hydroxide required for neutralizing 1 g of polymers which have an acidic component.

It is preferable that the adhesive composition of this invention contains an antistatic agent in order to provide antistatic performance. It is preferable that an antistatic agent is solid at normal temperature (for example, 30 degreeC), More specifically, it is an ionic compound whose melting | fusing point is 30 degreeC or more. Since such an antistatic agent has a low melting point compared with an alkali metal salt and has a long chain alkyl group, it is estimated that it is high in affinity with an acrylic copolymer.

An ionic compound having a melting point of 30 ° C. or higher is an ionic compound having a cation and an anion, and the cation is pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazollium cation, pyrrolidinium cation , the ammonium cation also including on a nitrogen onium cation or a phosphonium cation, or the like sulfonium cation and the anion is hexafluorophosphate phosphate (PF ₆ ^-), thiocyanate (SCN ^-), alkyl benzene sulfonate (RC ₆ H ₄ SO ₃ ^- may be an inorganic anion or an organic phosphorus compound such as a) ^-), perchlorate (ClO ₄ ^-), ₄ fluoride borate (BF _4. A melting point of 30 ° C. or more can be obtained depending on the chain length of the alkyl group, the position, the number of substituents, and the like. The cation is preferably a quaternary ammonium onium cation, a quaternary pyridinium cation or a quaternary pyridinium cation such as 1-alkyl pyridinium (the carbon atom at 2-6 may have a substituent or may be unsubstituted) Quaternary imidazolium cation such as 3-dialkyl imidazolium (the carbon atom at the 2, 4 and 5 positions may have a substituent or may be unsubstituted), quaternary ammonium cation such as tetraalkylammonium, etc. . As for melting | fusing point of an ionic compound, 30-80 degreeC is preferable. As a substituent which a cation may have, an alkyl group, an aryl group, etc. are mentioned. Since the ionic compound is not an alkali metal salt, the problem that conventional alkali metal salts have metal corrosiveness can be solved.

As for the (meth) acrylic-type polymer of the subject matter used for the adhesive composition of this invention, one or two or more types of the (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group is a main component, and adds another monomer as needed. It can synthesize | combine by making it superpose | polymerize. The polymerization method of the (meth) acrylic polymer is not particularly limited, and suitable polymerization methods such as solution polymerization and emulsion polymerization can be used.

When the adhesive composition of this invention forms an adhesive layer, it is preferable to crosslink an adhesive polymer. As a method for making a crosslinking reaction, an adhesive composition may contain a known crosslinking agent, and may crosslink by optical crosslinking, such as an ultraviolet-ray (UV). As a crosslinking agent, a bifunctional or trifunctional or more isocyanate compound, a bifunctional or trifunctional or more epoxy compound, a bifunctional or trifunctional or more acrylate compound, a metal chelate compound, etc. are mentioned.

Moreover, as other components, well-known additives, such as a silane coupling agent, antioxidant, surfactant, a crosslinking promoter, a plasticizer, a filler, a hardening accelerator, a hardening retarder, a processing aid, an antioxidant, can be mix | blended suitably. These can be used individually or in combination of 2 or more types.

It is preferable that the surface resistance value of the adhesive layer which bridge | crosslinked the said adhesive composition is 5.0x10 ⁺ 10 (ohm) / square or less. Moreover, it is preferable that the peeling electrification voltage of the said adhesive layer is +/- 0-1 kPa. In addition, in this invention, "+/- 1 to 1 microsecond" means 0-1 to 1 microsecond and 0 to +1 microsecond, ie, -1 to +1 microsecond. If the surface resistance value is large, the performance of discharging the static electricity generated by charging at the time of peeling is inferior. Thus, by sufficiently reducing the surface resistance value, the peeling electrification voltage generated with the static electricity generated when the adherend peels off the adhesive layer. This can be reduced, and the influence on the electric control circuit and the like of the adherend can be suppressed.

It is preferable that the gel fraction of the adhesive layer (crosslinked adhesive) which crosslinked the adhesive composition of this invention is 95 to 100%. By increasing the gel fraction in this way, the adhesive force does not become excessive when peeling at a low speed, the elution of the unpolymerized monomer or oligomer from the copolymer is reduced, and the durability in the antifouling property and the high temperature and high humidity is improved, and the adhesion of the adherend is improved. Contamination can be suppressed.

The adhesive film of this invention is an adhesive film in which the adhesive layer which bridge | crosslinked the adhesive composition of this invention was formed in one side or both sides of a resin film. Moreover, the surface protection film of this invention is a surface protection film in which the adhesive layer which bridge | crosslinked the adhesive composition of this invention was formed in one surface of the resin film. Since the adhesive composition of this invention has the outstanding antistatic performance, has corrosion resistance with respect to a to-be-adhered body, and is low in contamination, it bonds the surface protection film of this invention to a to-be-adhered body, and protects a surface through an adhesive layer. Even after peeling off the to-be-adhered body after overwriting the film with a ballpoint pen, there is no contamination transfer to the to-be-adhered body. For this reason, the surface protection film of this invention can be used suitably as a use of the surface protection film of a polarizing plate.

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

The base film can be subjected to antistatic treatment by antifouling treatment with a silicone-based, fluorine-based release agent, coat agent, silica fine particles, etc., application or mixing of antistatic agent, etc., on the side opposite to the side where the pressure-sensitive adhesive layer of the resin film is formed. .

The release film is subjected to releasing treatment by a silicone-based, fluorine-based releasing agent or the like on the side of the pressure-sensitive adhesive layer to be combined with the adhesive surface.

In the case of optical surface protection films, such as a surface protection film for polarizing plates, it is preferable that a base film and an adhesive layer have sufficient transparency.

(Example)

Hereinafter, the present invention will be described in detail with reference to Examples.

<Production of Adhesive Composition>

[Example 1]

Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube to replace the air in the reactor with nitrogen gas. Thereafter, 100 parts by weight of a solvent (ethyl acetate) was added to the reaction apparatus together with 100 parts by weight of 2-ethylhexyl acrylate and 5.0 parts by weight of 2-hydroxyethyl acrylate. Then, 0.1 weight part of azobis isobutyronitrile was dripped over 2 hours as a polymerization initiator, and it was made to react at 65 degreeC for 8 hours, and the acrylic copolymer solution was obtained. A part of acrylic copolymer was extract | collected and used as the measurement sample of the acid value mentioned later.

To this acrylic copolymer solution, 1.5 parts by weight of 1-octylpyridinium hexafluorophosphate, 1.5 parts by weight of coronate HX (isocyanurate of hexamethylene diisocyanate compound) and 0.02 part by weight of dioctyl tin dilaurate are added. And stirring and mixing, the adhesive composition of Example 1 was obtained.

EXAMPLES 2-4 AND COMPARATIVE EXAMPLES 1-3

Except having made the composition of a monomer and an additive each as the description of Table 1, it carried out similarly to the adhesive composition of the said Example 1, and obtained the adhesive composition of Examples 2-4 and Comparative Examples 1-3.

Here, (A) acrylic monomer, (B) hydroxyl group monomer, and (C) acidic monomer are added to the reaction apparatus before superposition | polymerization of an acrylic copolymer solution, (D) isocyanate (NCO) crosslinking agent, (E) crosslinking promoter, ( F) The antistatic agent was added to the acrylic copolymer solution after superposition | polymerization as an additive.

In Table 1, the compounding ratio of each component encloses the numerical value of the weight part which calculated | required the sum total of (A) group as 100 weight part in parentheses. Table 2 shows the compound names of the weak symbols of the respective components used in Table 1. In addition, Coronate (trademark) HX, HL, and L-45 are brand names of Nippon Polyurethane Industry Co., Ltd., and Takenate D-140N is a brand name of Mitsui Chemicals Corporation. Regarding the compound names of the isocyanate (NCO) crosslinking agent in Table 2, HDI, IPDI, and TMP mean hexamethylene diisocyanate, isophorone diisocyanate, and trimethylolpropane, respectively.

<Production of a surface protection film>

After apply | coating the adhesive composition of Example 1 on the peeling film which consists of a silicone resin-coated polyethylene terephthalate (PET) film, it removes a solvent by drying at 90 degreeC, and obtained the adhesive sheet whose thickness of an adhesive layer is 25 micrometers. . Thereafter, the adhesive sheet was transferred to a surface opposite to the antistatic and antifouling surface of the antistatic and antifouling polyethylene terephthalate (PET) film treated on one surface thereof, thereby preventing the antistatic and antifouling treatment. The surface protection film of Example 1 which has a laminated structure of "PET film / adhesive layer / peeling film (PET film coated with silicone resin)."

EXAMPLES 2-4 AND COMPARATIVE EXAMPLES 1-3

Instead of using the adhesive composition of Example 1, except using the adhesive composition of Examples 2-4 and Comparative Examples 1-3, respectively, it carried out similarly to the surface protection film of Example 1, The surface protection films of Comparative Examples 1-3 were obtained.

<Test Method and Evaluation>

After aging the surface protective films in Examples 1-4 and Comparative Examples 1-3 for 7 days in 23 degreeC and 50% RH atmosphere, the peeling film (silicone resin-coated PET film) was peeled off and an adhesive layer was After bonding the extruded thing on aluminum foil, it was made to stand as a corrosive measurement sample for 48 hours in 60 degreeC and 90% RH high temperature, high humidity atmosphere.

Moreover, after bonding the surface protection film which expressed this adhesive layer to the surface of the polarizing plate pasted on the liquid crystal cell via the adhesive layer, and leaving it for 1 day, it autoclave-processes 50 degreeC, 5 atmospheres for 20 minutes, and again at room temperature. What was left to stand for 12 hours was used as the measurement sample of adhesive force and peeling electrification voltage.

<Measurement method of acid value>

The acid value of the acryl copolymer was dissolved in a solvent (a mixture of diethyl ether and ethanol at a volume ratio of 2: 1), and 0.1 using the potentiometric automatic titration device (AT-610 manufactured by Kyoto Electronics). Potentiometric titration was performed with a potassium hydroxide ethanol solution having a concentration of about 0.1 mol / L using a potentiometric titration device, and the amount of potassium hydroxide ethanol solution required to neutralize the sample was measured. And the acid value was calculated | required from the following formula.

Acid value = (B x f x 5.611) / S

B = amount (ml) of 0.1 mol / l potassium hydroxide ethanol solution used for titration,

f = 0.1 mol / l A factor of the potassium hydroxide ethanol solution

S = mass of solids in the sample (g)

<Measurement of adhesive force>

Peeling strength (N / 25) which peeled and measured the measurement sample (surface protective film of 25 mm width which was bonded to the surface of a polarizing plate) obtained above at the tensile speed of 30 m / min using a tensile tester in 180 degree direction. Mm) was made into adhesive force.

<Measurement method of peeling large voltage>

The high-precision electrostatic sensor SK-035 and SK-200 (manufactured by Keyence Co., Ltd.) are used to measure the voltage (large voltage) generated when the polarizing plate is charged when the measurement sample obtained above is separated by 180 ° at a tensile speed of 30 m / min. It measured using and set the maximum value of the measured value as peeling electrification voltage.

<Evaluation Method of Corrosion>

After bonding a sample on aluminum foil, it left for 48 hours under the high temperature, high humidity conditions of 60 degreeCx90% RH. Then, the sample was peeled from the aluminum foil, the surface of the aluminum foil was visually confirmed, and the following reference | standard evaluated.

(Circle): Discoloration was not recognized on the aluminum foil surface.

(Triangle | delta): Partial discoloration was confirmed on the aluminum foil surface.

X: Discoloration was confirmed on the aluminum foil surface.

<Evaluation method of pollution>

After overwriting the surface protection film of the measurement sample obtained above with a ballpoint pen (load 500g, 3 round trips), it was left to 70 degreeC * 24hr. The surface protection film was peeled off from the polarizing plate, the surface of the polarizing plate was observed, it was confirmed that there was no contamination transfer in the polarizing plate, and the following reference | standard evaluated.

(Circle): There was no contamination in a polarizing plate.

(Triangle | delta): Contamination was confirmed in at least one part along the trace added with the ballpoint pen.

×: Along with the trace added with a ballpoint pen, contamination transition was confirmed, and detachment of the adhesive was also confirmed from the surface of the adhesive.

Table 3 shows the results of the tests and evaluations.

In Examples 1-4 which used the ionic compound whose melting | fusing point is 30 degreeC or more as an antistatic agent, it became excellent in antistatic performance, and also had corrosion resistance with respect to a to-be-adhered body, and also became low in contamination.

In Comparative Example 1 in which lithium perchlorate salt was used as the antistatic agent, the corrosiveness was large and the contamination was also slightly high.

In Comparative Example 2 in which the acid value of the acrylic polymer of the pressure-sensitive adhesive was used using bis (trifluoromethanesulfonyl) imide lithium salt as the antistatic agent, the antistatic performance was high due to the high peeling electrification voltage, high contamination resistance, and corrosiveness. It became a little big.

In Comparative Example 3 using trifluoromethanesulfonic acid lithium salt as the antistatic agent, the corrosiveness was slightly large and the contamination was slightly high.

Thus, in the surface protection films of Comparative Examples 1-3, (1) excellent antistatic performance, (2) corrosion resistance, and (3) prevention of generation | occurrence | production of an adhesive residue could not be satisfied simultaneously.

Claims (10)

The adhesive composition containing the (meth) acrylic-type polymer which has the (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group as a main component, The adhesive composition containing the ionic compound whose melting | fusing point is 30 degreeC or more. In the adhesive composition containing the (meth) acrylic-type polymer which has the (meth) acrylic acid ester monomer whose C1-C14 carbon number of an alkyl group as a main component, the acid value of the (meth) acrylic-type polymer is 30 or less and melting | fusing point is 30 degreeC or more Pressure-sensitive adhesive composition comprising a compound. 3. The method according to claim 1 or 2,
The adhesive composition in which the said (meth) acrylic-type polymer contains the (meth) acrylic-type monomer which has a hydroxyl group. The adhesive film which formed the adhesive layer which bridge | crosslinked the adhesive composition of Claim 1 or 2 in one side or both sides of a resin film. A pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of claim 3 is formed on one side or both sides of a resin film. The surface protection film which formed the adhesive layer which bridge | crosslinked the adhesive composition of Claim 1 or 2 in one surface of the resin film, after overwriting the surface protection film bonded to the to-be-adhered body via the said adhesive layer, The surface protection film which peels from a complex and does not carry out contamination to an adherend. A pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of claim 3 is formed on one surface of a resin film, and is overlaid on the surface-protective film bonded to the adherend through the pressure-sensitive adhesive layer with a ballpoint pen, and then peeled off from the adherend. , Surface protection film with no migration of contamination to adherends. The method according to claim 6,
The surface protection film used as a use of the surface protection film of a polarizing plate. The method according to claim 6,
The surface protection film which is given the antistatic and antifouling process on the surface opposite to the side in which the said adhesive layer of the said resin film was formed. The method of claim 8,
The surface protection film which is given the antistatic and antifouling process on the surface opposite to the side in which the said adhesive layer of the said resin film was formed.