JP2009275128A - Adhesive composition for surface protective film of optical member, and surface protective film for optical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic adhesive composition for surface protective films having excellent adhesiveness and reliability with little generation of static electricity by peeling electrification even in high-speed peeling during peeling of the film from an optical member of a large area as the surface protective film for optical members such as polarizing plates provided with a layer having fine unevennesses such as an anti-glare layer, and to provide an acrylic adhesive layer using the composition. <P>SOLUTION: The acrylic adhesive composition for surface protective films comprises, based on 100 pts.wt. of an acrylic copolymer (A) having reactive functional groups, a 300,000-1,000,000 weight-average molecular weight, and ≤-50°C Tg (glass transition temperature), 0.05-2.0 pts.wt. of an alkylene oxide chain-containing acrylic copolymer (B) having a 3,000-100,000 weight-average molecular weight, -20 to 20°C Tg (glass transition temperature), and an alkylene oxide chain of ≥20 alkylene oxide units in the molecule, and 0.005-0.6 pts.wt. of an alkali metal salt (C). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive composition for a protective film used for primary protection of the surface of an optical member such as a liquid crystal display panel, and in particular, is temporarily attached to the surface of the optical member during the production process. The present invention relates to a pressure-sensitive adhesive composition for a surface protective film that protects the surface during a process requiring protection and is peeled off after completion of the process, and has a low charge and good workability at the time of peeling.

Since the liquid crystal display panel is thin and light and consumes less power, it has been used in recent years as a screen display device for various information-related devices such as word processors and notebook personal computers. In such a liquid crystal display plate, an optical member such as a polarizing plate or a retardation plate is used together with a glass cell (liquid crystal cell) containing liquid crystal as a main body.

These optical members are usually further coated with a surface protective film so that the surface is not contaminated or damaged during each process such as punching, inspection, transportation, and assembly of the liquid crystal display panel. The surface protection film is peeled and removed from the optical member when the surface protection is no longer necessary.

While such a surface protective film is required to protect the surface of the optical member, the surface protective film adheres to the surface to such an extent that the optical member does not slip or fall off from the surface. In order not to interfere with various inspections such as the performance of the liquid crystal, it must be highly transparent, and there should be no defects in the adhesive layer such as bulge, tunneling, peeling, and the interface between the adhesive layer and the optical member. Required. When peeling the film from the optical member, in order not to damage the optical member or the liquid crystal cell due to the distortion caused by the peeling, and so as not to cause inconvenience such as the optical member peeling from the liquid crystal cell, It must be easily peelable.
In recent years, the speed of peeling of the surface protective film tends to be increased for the purpose of improving working efficiency, and workability in high-speed peeling has been required as a characteristic of the adhesive.

In order to solve these problems, many proposals have been known. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 9-208910) describes a copolymerizable alkyl ester having an alkyl group having 1 to 9 carbon atoms as a main component and containing a hydroxyl group and / or a carboxyl group. Crosslinks such as isocyanates to acrylic copolymers obtained by copolymerizing specific amounts of unsaturated monomers, alkyl (meth) acrylic acid alkyl esters having 16 to 22 carbon atoms and reactive emulsifiers. An adhesive composition comprising a specific amount of an agent and a surface protective film using the same are disclosed.

However, the surface protection film using the above-mentioned pressure-sensitive adhesive was able to suppress the occurrence of swelling and tunneling, but re-peelability is still not sufficient, and its peel strength is practical. It turned out to be so large that it could not be used.

For example, in Patent Document 2 (Japanese Patent Laid-Open No. 2001-33624), there is basically no separation from an optical member due to environmental changes such as temperature and humidity, and separation and separation from the optical member without any adhesive residue at the time of separation. A surface protective film intended to obtain a surface protective film that can be easily peeled and separated without damage to the optical member or peeling from the liquid crystal cell even after heat treatment such as aging while satisfying the performance, A surface protective film is disclosed in which the adhesive strength when left at 80 ° C. is within 1.3 times the adhesive strength when left at room temperature at 180 ° peeling at a peeling speed of 300 mm / min.

However, the adhesive of the second proposal has an adhesive strength test using a stainless steel plate as an adherend, and the adhesive strength after standing at 80 ° C. is within 1.3 times the adhesive strength when left at room temperature. For example, when a polarizing plate having an antiglare layer on the surface is used as the adherend, an aging treatment is carried out at 90 ° C. for 2 hours after the autoclave treatment. It has been found that there are problems such as the occurrence of numerous blisters.

The inventors of the present invention have made researches on improving acrylic pressure-sensitive adhesives, and in Patent Document 3 (Japanese Patent Laid-Open No. 2003-41229), Patent Document 4 (Japanese Patent Laid-Open No. 2005-97451), etc. An adhesive composition is proposed.

The composition proposed in Patent Document 4 showed good properties in a good balance when used in a liquid crystal display member having a small area, but the large area due to the increase in the size of the liquid crystal display member. In the application for protecting the display member, the adhesive force at high-speed peeling is too large, which hinders the peeling work. Therefore, it is necessary to reduce the peeling force at high speed while maintaining a sufficient adhesive force (peeling force at low speed) in the protective film protecting a large area.

On the other hand, the generation of static electricity is generally unavoidable when a film is applied or peeled off. When static electricity is generated on the surface protection film in this application, dust and dust are adsorbed on the surface of the optical film and become a product. Inconvenience arises. Moreover, when big static electricity generate | occur | produces when peeling a protective film, there exists a possibility that the circuit of a display member may be destroyed.
Therefore, an antistatic layer containing an antistatic agent is provided on a part of the surface protective film to impart antistatic performance. For example, Patent Document 5 (Japanese Patent Laid-Open No. 2000-273417) discloses a fourth class. A surface protective film having an antistatic layer containing an ammonium salt is disclosed. However, in this surface protection film, since the antistatic treatment is performed on the support side, the surface protection film side can be prevented from being charged, but the object to be protected cannot be prevented from being charged. There was a problem that the object to be protected was charged.

Further, in Patent Document 6 (Japanese Patent Laid-Open No. 2005-330464), Patent Document 7 (Japanese Patent Laid-Open No. 2005-131957), Patent Document 8 (Japanese Patent Laid-Open No. 2007-297446), etc., an ionic liquid is used as the adhesive layer. In addition, a pressure-sensitive adhesive is disclosed in which the amount of static electricity generated by peeling charging is reduced by adding an alkyltrimethylammonium salt, polyether polyol, or the like as an antistatic component. However, the surface protective film having the pressure-sensitive adhesive layer has an antistatic effect, but has problems in terms of durability (heat resistance, moist heat resistance) as a surface protective film and a decrease in adhesive strength.

As a result of further research, the present inventors have proposed in Patent Document 9 (Japanese Patent Laid-Open No. 2008-69202) to use a specific antistatic agent for the pressure-sensitive adhesive layer in which the blend resin is non-uniformly crosslinked. . However, the amount of static electricity increases with the increase in screen size, and it has been difficult to prevent sufficient charging. Furthermore, there is a problem that the surface protective film is peeled off due to insufficient cohesive force in the process until the surface protective film is peeled off from the object to be protected.
JP-A-9-208910 JP 2001-33624 A JP 2003-41229 A JP-A-2005-97451 JP 2000-273417 A Japanese Patent Laying-Open No. 2005-330464 JP 2005-131957 A JP 2007-297446 A JP 2008-69202 A

The problem to be solved by the present application is that an optical member such as a polarizing plate provided with a layer having fine irregularities such as an antiglare layer can be used as a surface protection film for an optical member without damaging the adherend. Acrylic pressure-sensitive adhesive composition for surface protective film with less adhesive generation and high reliability in high-speed peeling when peeling the film from a member, and an acrylic pressure-sensitive adhesive layer using the same Is to provide.

As a result of further research, the present inventors have contained 0.1 to 10% by weight of a monomer having a hydroxyl group as a copolymerization component, a weight average molecular weight of 300,000 to 1,000,000, and a glass transition temperature (Tg ) With respect to 100 parts by weight of the acrylic copolymer (A) having a temperature of −50 ° C. or lower,
An alkylene oxide chain-containing acrylic system having a weight average molecular weight of 30,000 to 100,000, a glass transition temperature (Tg) of −20 ° C. to 20 ° C., and having 20 or more alkylene oxide chains in the molecule Copolymer (B) 0.05 to 2.0 parts by weight,
And alkali metal salt (C) 0.005 to 0.6 parts by weight
(However, the amount of alkali metal salt (C) does not exceed the amount of acrylic copolymer (B).)
An acrylic pressure-sensitive adhesive composition for a surface protective film.
Found that this problem could be solved, and further researched to complete the present invention.

The acrylic pressure-sensitive adhesive composition of the present invention has a specific structure and a specific glass transition temperature for the acrylic copolymer (A) having a specific molecular weight range containing a reactive functional group as a crosslinking point and a specific glass transition temperature range. It is a pressure-sensitive adhesive composition having antistatic properties in which an alkylene oxide chain-containing acrylic copolymer (B) in the range and an alkali metal salt are blended.

By being configured in this manner, the surface protective film using the acrylic pressure-sensitive adhesive composition of the present invention has the surface protection and high transparency of the optical member, and also has good conformability, Even if it is used for an optical member such as a polarizing plate provided with a layer having fine irregularities such as an anti-glare layer on its surface, it does not move even after an autoclave treatment or subsequent work and heat history during use. In addition, no defects in the adhesive layer such as tunneling, peeling, etc. were observed, and even when the film was peeled from a large area optical member, there was little generation of static electricity due to peeling charging even at high speed peeling, and good peeling characteristics were obtained. And easy peeling without causing inconveniences such as disorder of alignment of the optical member or liquid crystal cell, expansion of the cell gap, peeling of the optical member from the liquid crystal cell, etc. Can, in which the resin can impart effective antistatic properties at a small amount by the combination of antistatic components without blending.

The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing a specific acrylic copolymer (A), a specific acrylic copolymer (B), and an alkali metal salt (C).

The acrylic copolymer (A) of the present invention is an acrylic copolymer (A) having a weight average molecular weight (Mw) of 300,000 to 1,000,000, and the weight average molecular weight (Mw) is preferably 40. It should be 10,000 to 800,000. If the weight average molecular weight (Mw) is equal to or greater than the lower limit, the adhesive force during re-peeling will not be too high, and damage to the optical member or failure of the optical member will not occur even if heat treatment is performed. It is preferable because the surface protective film can be easily peeled off. On the other hand, if the upper limit is not exceeded, the fluidity of the resulting pressure-sensitive adhesive layer is excellent, and the pressure-sensitive adhesive sufficiently covers the surface of the polarizing plate even when used for a polarizing plate having minute irregularities on the surface. Since it can be wetted, it is preferable because no swelling occurs between the polarizing plate surface and the pressure-sensitive adhesive layer of the surface protective film.

The weight average molecular weight (Mw) of the acrylic copolymer (A) is a value measured by the following method. Measuring method of weight average molecular weight (Mw) It measures according to the following (1)-(3). (1) An acrylic copolymer solution is applied to a release sheet and dried at 100 ° C. for 2 minutes to obtain a film-like acrylic copolymer. (2) The film-like acrylic copolymer obtained in (1) above is dissolved in tetrahydrofuran so that the solid content is 0.2%. (3) The weight average molecular weight (Mw) of the acrylic copolymer (A) is measured using gel permeation chromatography (GPC) under the following conditions.

(Conditions) GPC: HLC-8220 GPC [manufactured by Tosoh Corporation] Column: TSK-GEL GMHXL 4 mobile phase solvents: tetrahydrofuran flow rate: 0.6 ml / min Column temperature: 40 ° C

The glass transition temperature (Tg) of the acrylic copolymer (A) is preferably −50 ° C. or lower, more preferably −55 to −80 ° C. If Tg is too high above the temperature, the pressure-sensitive adhesive layer is hard and difficult to flow, and particularly when used for a polarizing plate having an anti-glare layer on the surface, the pressure-sensitive adhesive has sufficient surface irregularities. This is not preferable because it cannot be wetted and, therefore, swelling may occur between the polarizing plate surface and the pressure-sensitive adhesive layer of the surface protective film.

In the present invention, the glass transition temperature (Tg) of the acrylic copolymer (A) is a value determined by measurement as follows. Glass transition temperature (Tg) Measured according to the following (1) to (3). (1) An acrylic copolymer solution is applied to a release sheet and dried at 100 ° C. for 2 minutes to obtain a film-like acrylic copolymer. (2) A measurement sample is prepared by weighing about 10 mg of the sample obtained in (1) into a cylindrical cell made of aluminum foil with a thickness of about 0.05 mm and having an inner diameter of about 5 mm and a depth of about 5 mm. (3) Using an SSC-5000 type differential scanning calorimeter manufactured by Seiko Denshi Kogyo Co., Ltd., the temperature is measured from −150 ° C. at a heating rate of 10 ° C./min.

The acrylic copolymer (A) of the present invention contains a monomer having a hydroxyl group. Examples of the monomer having a hydroxyl group include a (meth) acrylic monomer having a hydroxyl group and another monomer having a hydroxyl group. Examples of the (meth) acrylic monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-butyl (meth) acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl- 3-hydroxyhexyl (meth) acrylate, glycerol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate , Polyethylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, and the like. Other monomers having a hydroxyl group include N-methylolacrylamide, allyl alcohol, And methallyl alcohol.

Among these monomers, good compatibility and copolymerization with other monomers when copolymerizing with other monomers to synthesize acrylic copolymer (A), and From the viewpoint of good crosslinking reaction with the crosslinking agent, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred.

The content of the hydroxyl group-containing monomer contained in the acrylic copolymer (A) molecule as a copolymerizable component is 0.1 to 10.0% by weight, preferably based on the acrylic copolymer (A). Is preferably contained in an amount of 2.0 to 8.0% by weight so that if the copolymerization amount is not less than the lower limit value, there is no contamination of the adherend, while if less than the upper limit value, the compatibility ( No problem with wettability.

In the present invention, 50% by weight or more of all monomer components constituting the acrylic copolymer (A) (the monomer constituting the copolymer may be simply referred to as a copolymer component), Preferably, it refers to a copolymer in which 90% by weight or more is an acrylic monomer.

Examples of the acrylic monomer include methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, and i-nonyl acrylate. Linear or branched alkyl esters of acrylic acid such as n-decyl acrylate, n-dodecyl acrylate, stearyl acrylate, etc., such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, A linear or branched alkyl ester having 1 to 18 carbon atoms of methacrylic acid such as n-dodecyl methacrylate and stearyl methacrylate, and one or more of these various derivatives can be selected.

The acrylic copolymer (A) is a copolymer having an acrylic monomer as a main component, but other types of monomers are within the range in which the constituent amount of the monomer is not impaired. And can be used as a polymerization component of the acrylic copolymer (A).

Examples of the other types of monomers include aromatic monovinyl monomers such as styrene, α-methyl styrene, t-butyl styrene, p-chloro styrene, chloromethyl styrene, and vinyl toluene; for example, acrylonitrile and methacrylonitrile. Vinyl cyanide monomers; for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, and various other derivatives thereof.

The acrylic copolymer (A) may contain a monomer having a functional group other than a hydroxyl group as a copolymerizable component. For example, a carboxyl group-containing monomer, a glycidyl group-containing monomer, an amide group , N-substituted amide group-containing monomers, tertiary amino group-containing monomers and the like can be used alone or in combination.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, and monohydroxyethyl (meth) acrylate succinate. , Monohydroxyethyl (meth) acrylate maleate, monohydroxyethyl (meth) acrylate fumarate, monohydroxyethyl (meth) acrylate phthalate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic And acid dimer, ω-carboxy-polycaprolactone mono (meth) acrylate, and the like.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, glycidyl vinyl ether, 3,4-epoxycyclohexyl vinyl ether, glycidyl (meth) allyl ether, 3,4 -Epoxy cyclohexyl (meth) allyl ether etc. are mentioned.

Examples of amide group and N-substituted amide group-containing monomers include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-ethoxy. Examples include methyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-tert-butylacrylamide, N-octylacrylamide, diacetone acrylamide and the like.

Examples of the tertiary amino group-containing monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and the like.

The acrylic pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer (B) containing an alkylene oxide chain having a specific structure and a specific glass transition temperature range.

The acrylic copolymer (B) of the present invention has an average molecular weight (Mw) containing an alkylene oxide chain-containing acrylic monomer as a copolymerization component of 30,000 to 100,000, preferably 50,000 to 6. It is a 100,000 acrylic copolymer (B). If the average molecular weight (Mw) is 30,000 or more, sufficient adhesive strength is obtained, and if it is less than 60,000, sufficient compatibility is obtained.

The weight average molecular weight (Mw) of the acrylic copolymer (B) can be measured by the same method as the weight average molecular weight (Mw) of the acrylic copolymer (A).

The glass transition temperature (Tg) of the acrylic copolymer (B) is preferably −20 ° C. to 20 ° C., more preferably −10 to 15 ° C. If Tg is −20 ° C. or higher, sufficient adhesive strength can be obtained, and if it is 20 ° C. or lower, substrate adhesion does not decrease.

Moreover, it is preferable that it is more than the said lower limit since durability cannot be ensured without the cohesion force deficiency etc. arising.

In the present invention, the glass transition temperature (Tg) of the acrylic copolymer (B) is measured by the same method as that for measuring the glass transition temperature (Tg) of the acrylic copolymer (A).

In the present invention, the acrylic copolymer (B) refers to all monomer components constituting the acrylic copolymer (B) (the monomer constituting the copolymer is simply referred to as a copolymer component). Of 50% by weight or more, preferably 70% by weight or more of the acrylic monomer.

As the acrylic monomer, the same acrylic monomer as that described in the acrylic copolymer (A) can be used.

In the present invention, the acrylic copolymer (B) contains an alkylene oxide chain-containing acrylic monomer having an alkylene oxide chain in the molecule as a copolymer component.

Examples of the acrylic monomer having an alkylene oxide chain used in the present invention include an acrylic monomer having an ethylene oxide chain and a propylene oxide chain, such as polyethylene glycol (meth) acrylate and methoxypolyethylene glycol (meth). Examples include acrylate, methoxypolypropylene glycol (meth) acrylate, and polypropylene glycol (meth) acrylate, and methoxypolyethylene glycol (meth) acrylate is preferable.

The alkylene oxide unit needs to be 20 or more, and preferably 40 or more. If the alkylene oxide unit contains an acrylic monomer having 20 or more as a copolymerization component, a remarkable antistatic effect can be exhibited by a combination with an alkali metal salt described later.

Further, the acrylic copolymer (B) may contain another monomer having a functional group such as a carboxyl group or a hydroxyl group as a constituent component.

As the monomer having the functional group, other monomers having the same functional group as those described in the acrylic copolymer (A) can be used.

The polymerization method of the acrylic copolymer (A) and the acrylic copolymer (B) used in the present invention is not particularly limited, and may be a known method such as solution polymerization, emulsion polymerization, suspension polymerization. Although it is possible to polymerize, when the pressure-sensitive adhesive composition of the present invention is produced using the acrylic copolymer obtained by polymerization, it is polymerized by solution polymerization because the treatment process is relatively simple and can be performed in a short time. Is preferred.

In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent used as needed are generally charged in a polymerization tank, and stirred in a nitrogen stream or at the reflux temperature of the organic solvent. However, a known method can be used, for example, by performing a heating reaction for several hours.

In addition, the weight average molecular weights of the acrylic copolymer (A) and the acrylic copolymer (B) of the present invention can be easily adjusted by the reaction temperature, time, amount of solvent, type and amount of catalyst.

Acrylic copolymer (A)
In the polymerization of the acrylic copolymer (B), examples of the organic solvent for polymerization include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, Aromatic hydrocarbons such as tetralin, decalin, aromatic naphtha; fats such as n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil Or alicyclic hydrocarbons; for example, esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate For example, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, methylcyclohex Ketones such as non; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; and alcohols such as n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol. These organic solvents can be used alone or in admixture of two or more.

Among these organic solvents for polymerization, the acrylic copolymer (A)
In the polymerization of the acrylic copolymer (B), it is preferable to use an organic solvent that does not easily cause chain transfer during the polymerization reaction, for example, esters and ketones, and particularly the solubility of the acrylic copolymer. From the viewpoint of ease of polymerization reaction, use of ethyl acetate, acetone or the like is preferable.

As said polymerization initiator, it is possible to use the organic peroxide, an azo compound, etc. which can be used by normal solution polymerization.
Examples of such organic peroxides include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, and di-i-propyl peroxydicarbonate. , Di-2-ethylhexyl peroxydicarbonate, t-butyl peroxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4- Di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) Propane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-t-octylpero Examples of azo compounds include 2,2′-azobis-i-butyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, and 2,2′-azobis-4. And -methoxy-2,4-dimethylvaleronitrile.

  Among these organic peroxides, in the polymerization of the acrylic copolymer (A) and the acrylic copolymer (B), a polymerization initiator that does not cause a graft reaction during the polymerization reaction is preferable. preferable. The amount used is usually 0.01 to 2.0 parts by weight, preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the total amount of monomers.

In the production of the acrylic copolymer (A) and the acrylic copolymer (B) used in the present invention, it is normal not to use a chain transfer agent, but the object and effect of the present invention are impaired. It is possible to use it as necessary within a range.
Examples of such chain transfer agents include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; anthracene, phenanthrene, fluorene, 9 -Aromatic compounds such as phenyl fluorene; aromatic nitro compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene; benzoquinone, 2, 3, 5, Benzoquinone derivatives such as 6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloro Halo such as methane, tribromomethane, 3-chloro-1-propene Hydrocarbons; aldehydes such as chloral and fulleraldehyde: alkyl mercaptans having 1 to 18 carbon atoms; aromatic mercaptans such as thiophenol and toluene mercaptan; alkyl esters having 1 to 10 carbon atoms of mercaptoacetic acid and mercaptoacetic acid C1-C12 hydroxyalkyl mercaptans; Terpenes such as vinylene and terpinolene;

  The polymerization temperature is generally about 30 to 180 ° C, preferably 40 to 150 ° C, more preferably 50 to 90 ° C.

  When an unreacted monomer is contained in a polymer obtained by a solution polymerization method or the like, it can be purified by a reprecipitation method using methanol or the like in order to remove the monomer.

The alkali metal salt (C) used in the present invention is a metal salt having lithium, sodium or potassium as a cation.
Specifically, cations such as Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ^{_{3 sO 2) 2 N -,}} (C 2 F 5 sO 2) 2 N -, (CF 3 sO 2) 3 C - metal salt composed of anions or the like is preferably used. In particular, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) Lithium salts such as ₃ C are preferably used. Among them, fluoromethylsulfonyllithium salts such as LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C have antistatic effects, It is particularly preferable because of its good metal corrosivity. These alkali metal salts may be used alone or in combination of two or more.

About the compounding quantity of the alkali metal salt of the said adhesive composition, 0.005-0.6 weight part of alkali metal salt is preferable with respect to 100 weight part of acrylic copolymers (A), Preferably 0.005. More preferably, it is added in an amount of 0.01 to 0.2 parts by weight. If it is more than 0.005 parts by weight, sufficient charging characteristics cannot be obtained. On the other hand, if it is less than 0.6 parts by weight, the antistatic effect rate relative to the blending amount is sufficient, which is preferable.

The pressure-sensitive adhesive for a surface protective film of the present invention is crosslinked with an isocyanate compound (D) to form an acrylic pressure-sensitive adhesive layer for a surface protective film.
Examples of the polyisocyanate compound (D) that can be used in the present invention include aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate; for example, hexamethylene diisocyanate and isophorone diisocyanate. Aliphatic or alicyclic polyisocyanates such as hydrogenated products of the aromatic polyisocyanate compounds; dimers or trimers of these polyisocyanates or adducts of these polyisocyanates with polyols such as trimethylolpropane, etc. Polyisocyanate compounds derived from various polyisocyanates of the above can be mentioned, but among these isocyanate compounds, hexamethylene diisocyanate is Particularly preferred.
These isocyanate compounds can be used alone or in admixture of two or more.

These isocyanate compounds include, for example, “Coronate HX”, “Coronate HL-S”, “Coronate 2234”, “Aquanate 200”, “Aquanate 210” (manufactured by Nippon Polyurethane Co., Ltd.), “Desmodur N3400” [ "Sumitomo Bayer Urethane Co., Ltd.", "Duranate E-405-80T", "Duranate 24A-100", "Duranate TSE-100" [Asahi Kasei Kogyo Co., Ltd.], "Takenate D-110N", "Takenate D" -120N "," Takenate M-631N "," MT-Olestar NP1200 "(manufactured by Mitsui Takeda Chemical Co., Ltd.) and the like can be suitably used.

The amount of these polyisocyanate compounds (D) used is 0.3 to 1.2 equivalents as isocyanate groups when the total of the reactive functional groups of the acrylic copolymers (A) and (B) is 1 equivalent. In particular, a range of 0.5 to 0.9 equivalent is preferable, and a curing catalyst such as dibutyltin laurate may be used as necessary.

In addition to the acrylic copolymer (A) acrylic copolymer (B) and the alkali metal salt (C) described above, the pressure-sensitive adhesive composition for an optical member surface protective film of the present invention, if necessary. Formulations to be blended into the surface protective film pressure-sensitive adhesive composition, such as weather resistance stabilizer, tackifier, plasticizer, softener, peeling aid, dye, pigment, inorganic filler, surfactant, etc. It can mix | blend suitably.

Among them, when used for high-speed peeling in a large area, it is preferable to mix a peeling aid, and a peeling compound is used as a peeling aid, which has a small peeling force and does not cause zipping and has excellent adhesive strength in low-speed peeling. Mixing is a preferred embodiment, and among them, it is preferable to contain a polyoxyalkylene-modified dimethyl silicon compound.

Examples of the polyoxyalkylene-modified dimethyl silicon compound include compounds in which the side chain of dimethyl silicon is substituted with a polyoxyalkylene group, compounds in which the terminal portion of methyl silicon is substituted with a polyoxyalkylene group, side chains of dimethyl silicon and both Examples thereof include compounds in which the terminal is substituted with a polyoxyalkylene group.

Examples of the polyoxyalkylene group include polyoxyethylene, polyoxypropylene, polyoxybutylene, and block compounds thereof.

Examples of the polyoxyalkylene-modified dimethylsilicon compound (B) include “KF-351A”, “KF-352A”, “KF-353”, “KF-354L”, “KF-355A”, “KF-615A”. ”,“ KF-945 ”,“ KF-640 ”,“ KF-641 ”,“ KF-642 ”,“ KF-643 ”,“ KF-6020 ”,“ X-22-6191 ”,“ X-22 ” -4515 "," KF-6011 "," KF-6012 "," KF-6013 "," KF-6015 "," KF-6016 "," KF-6017 "," X-22-4741 "," KF -1002 "," X-22-4952 "," X-22-4272 "," X-22-6266 "," KF-6004 "," KP-301 "," KP-323 "," KP-354 " "," KP 355 "," KP-341 "," KP-118 "," F-501 "," X-22-6191 "," X-22-3506 "," X-22-3004 "," KF-6005 " , “KP-101”, “KF-889”, “KF-6003”, “X-22-4515”, “F-3031”, “X-24-1430”, “X-22-4991”, “ KP-208 "," KF-6003 "(manufactured by Shin-Etsu Chemical Co., Ltd.)," L-720 "," L-7604 "," Y-7006 "," BY-16-201 "," FZ-77 " ”,“ FZ-2101 ”,“ FZ-2104 ”,“ FZ-2110 ”,“ FZ-2118 ”,“ FZ-2120 ”,“ FZ-2122 ”,“ FZ-2130 ”,“ FZ-2161 ”, "FZ-2162", "FZ-2163", "FZ-2 64 "," FZ-2166 "," FZ-2191 "," FZ-2154 "," FZ-2203 "," FZ-2207 "," FZ-2208 "," L-7001 "," L-7002 " , “SF-8427”, “SF-8428”, “SH-3749”, “SH-3773M”, “SH-8400”, “FZ-5609”, “FZ-7001”, “FZ-7002” [Toray Industries, Inc. -Dow Co., Ltd.], "TSF-4440", "TSF-4441", "TSF-4445", "TSF-4446", "TSF-4450", "TSF-4442", "TSF-4460" [ Momentive Performance Co., Ltd.).

In addition to the polyoxyalkylene-modified dimethylsilicon compound, silicone oil may be appropriately combined in accordance with the purpose.

The amount of the polyoxyalkylene-modified dimethylsilicone compound contained in the pressure-sensitive adhesive composition is 0.01 to 2.0 parts by weight with respect to 100 parts by weight of the acrylic copolymer (A), Preferably it is 0.05-1.0 weight part, More preferably, it is 0.1-0.5 weight part.

When the amount of the polyoxyalkylene-modified dimethylsilicone compound contained in the pressure-sensitive adhesive composition is less than the lower limit, the surface of the protective film is subjected to external stress and the pressure-sensitive adhesive layer of the surface protective film If a part of the pressure-sensitive adhesive layer is broken, a part of the pressure-sensitive adhesive layer destroyed when the surface protective film is peeled off remains on the surface of the optical member. When the amount of the polyoxyalkylene-modified dimethylsilicon compound contained in the pressure-sensitive adhesive composition exceeds the upper limit, the adhesiveness of the surface protective film changes with time, and the surface of the optical member Excess dimethylsilicon compound remains and causes surface contamination.

The pressure-sensitive adhesive composition for an optical member surface protective film of the present invention thus obtained is used to produce an optical member surface protective film, and is prepared on at least one surface of an appropriate transparent surface protective substrate by a conventionally known method. Used to form a layer.

As a base material used for the surface protection film of this invention, it is required that it is a base material which can apply | coat an adhesive. From the viewpoint of inspection and management of optical members by fluoroscopy as the base resin, for example, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, A film made of an acrylic resin can be exemplified, but a polyester resin is preferable from the viewpoint of surface protection performance, and a polyethylene terephthalate resin is particularly preferable in consideration of practicality.

The thickness of the substrate is generally 500 μm or less, preferably 5 to 300 μm, more preferably about 10 to 200 μm. An antistatic layer may be provided on one or both surfaces of these base materials for the purpose of preventing antistatic during peeling. The surface of the substrate on the side where the pressure-sensitive adhesive layer is provided may be subjected to a corona discharge treatment or the like in order to improve the adhesion with the pressure-sensitive adhesive layer.

For example, it has sufficient adhesion to large optical members such as those used for LCD screens of 20 inches or more (adhesive force for low-speed peeling is sufficient) and can be easily peeled off at high-speed peeling (adhesion for high-speed peeling) It is necessary that the force does not increase) and the conformability is good (the cut end does not turn up when cut).
That is, the adhesive force of 180 ° peel to the optical member at 23 ° C. is 0.05 N / 25 mm or more, preferably 0.08 N / 25 mm at a peeling speed of 0.3 m / min (low speed peeling). It is preferable that the adhesive force for low-speed peeling is less than 0.05 N / 25 mm because turning and shifting are likely to occur.

Further, since the workability of high-speed peeling in a large area is reduced when the adhesive force is increased, the adhesive force (peeling force) does not become 1.5 N / 25 mm or more at a peeling speed of 30 m / min (high-speed peeling), preferably It is preferable not to be larger than 1.2 N / 25 mm.

Furthermore, since the optical member is damaged when the charge at the time of peeling is large, the pressure-sensitive adhesive composition of the present invention preferably has a peeling voltage of 0.9 KV or less at 30 m / min against the antiglare polarizing plate. More preferably, it is less than 0.5 KV, and particularly preferably less than 0.3 KV.

In order to prevent charging on the film side at the time of peeling, the pressure-sensitive adhesive composition of the present invention has a surface resistance value of 1E + 13 (Ω / □) or less, preferably 1E + 11 (Ω / □) or less. preferable.

The thickness of the pressure-sensitive adhesive layer formed on the substrate can be appropriately set according to the adhesive force required for the protective film or the surface roughness of the optical member, and is generally 1 to 100 μm, preferably 5 to 50 μm. More preferably, a thickness of about 15 to 30 μm can be exemplified.

As a method for forming the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition of the present invention is directly or as necessary diluted with an appropriate solvent, and this is directly applied to a surface protective base film and dried to remove the solvent. Can be adopted. First, the pressure-sensitive adhesive composition of the present invention is applied on a release sheet made of an appropriate film such as paper or polyester film that has been subjected to a release treatment with a silicone resin, and then dried by heating to form a pressure-sensitive adhesive layer. Then, the adhesive layer side of the release sheet can be pressed against the surface protective base film to transfer the adhesive layer to the protective film.

The protective film thus obtained is laminated on the surface of the optical member to protect the surface of the optical member from being contaminated or damaged, and when the optical member is processed into a liquid crystal display panel or the like, While the protective film is laminated on the optical member, it is used in various processes such as punching, inspection, transportation, and assembly of the liquid crystal display panel. If necessary, heat and pressure such as autoclaving and high-temperature aging When the surface treatment is no longer necessary, the optical member is peeled off and removed.

EXAMPLES Examples and comparative examples will be described below to specifically describe the effects of the present invention, but the present invention is not limited to these examples. In addition, preparation of a test piece and various test methods and evaluation methods used in Examples and Comparative Examples are as follows.

(1) Preparation of test pressure-sensitive adhesive sheet A pressure-sensitive adhesive composition was applied on a release paper surface-treated with a silicone-based release agent so that the coating amount after drying was 20 g / m ^2, and 100 ° C. After drying with a hot-air circulating dryer for 60 seconds to form an adhesive layer, the adhesive layer surface is in contact with a polyethylene terephthalate (PET) film [trade name; E5001; manufactured by Toyobo Co., Ltd.]. After mounting and pressure bonding through a pressure nip roll, the surfaces were cured at 23 ° C. and 50% RH for 10 days to obtain a test surface protective film.

(2) Appearance of pressure-sensitive adhesive layer Before the appearance, observe whether the pressure-sensitive adhesive layer of the test surface protective film prepared according to the item (1) is uniform and transparent.
○: The pressure-sensitive adhesive layer is uniform and transparent. Δ: The pressure-sensitive adhesive layer is uniform but cloudy. ×: Defects are found in the pressure-sensitive adhesive layer.

(3) Measurement of adhesive strength
After the surface protective film for test prepared in the preceding item (1) was cut to 25 mm × 150 mm, the surface protective film piece was subjected to anti-glare treatment using a desktop laminator [trade name: SQ-1852AP- AG6; manufactured by Sumitomo Chemical Co., Ltd.] was used as a test sample. After leaving this sample under conditions of 23 ° C. and 50% RH for 24 hours (conditioning treatment), the adhesive strength at 180 ° peeling was peeled off at a peeling speed of 0.3 m / min (low speed peeling) and 30 m / min (high speed peeling). Each was measured.

(4) Before observation of surface state of polarizing film after peeling The surface state of the polarizing film after peeling of the test sample tested in the item (3) was observed.
○: Abnormalities such as adhesive residue on the surface are not observed.
X: Abnormalities such as adhesive residue are observed on the surface.

(5) Before the stripping voltage measurement, the test surface protective film prepared according to the item (1) was cut into 25 mm × 150 mm, and then the surface protective film piece was antiglare-treated with a polarizing film [ Trade name: SQ-1852AP-AG6; manufactured by Sumitomo Chemical Co., Ltd.] was used as a test sample. This sample is allowed to stand for 24 hours under the conditions of 23 ° C. and 50% RH (conditioning treatment), and then peeled off at 180 ° and at a peeling speed of 30 m / min (high-speed peeling conditions). The potential of the polarizing plate surface generated at this time was measured with a potential measuring device (KSD-0303 manufactured by Kasuga Electric Co., Ltd.) fixed at a predetermined position as shown in the following figure. The measurement was performed in an environment of 23 ° C. × 50% RH.

(6) Surface resistance The release paper of the obtained pressure-sensitive adhesive sheet was peeled off, and the surface resistance value of the pressure-sensitive adhesive layer surface was measured using a surface resistance measurement device (Advantest Co., Ltd .: R12704 RESISTIVITY CHAMBER).

Production and production example 1 of acrylic copolymer (A) solution
In a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 20 parts by weight of ethyl acetate and 10 parts by weight of toluene are placed, and in another container, 2-ethylhexyl as a monomer (a ₁ ). 95.0 parts by weight of acrylate (2EHA) and 5.0 parts by weight of 4-hydroxybutyl acrylate (4HBA) as monomer (a ₂ ) are mixed to form a monomer mixture, 25% of which is contained in a reaction vessel Then, after replacing the air in the reaction vessel with nitrogen gas, 0.02 part by weight of azobisbutyronitrile (hereinafter referred to as AIBN) was added as a polymerization initiator, and the mixture was stirred in a nitrogen atmosphere. The temperature of the mixture in the reaction vessel was raised to 70 ° C. to initiate an initial reaction. After the initial reaction was almost completed, the remaining monomer mixture 75% and ethyl acetate 20 parts by weight, toluene 10 parts by weight and AIBN 0.2 part by weight were respectively reacted for about 2 hours, followed by subsequent reaction. The reaction was further continued for 2 hours. Then, AIBN was added to 25 parts by weight of toluene.
A solution having 0.25 parts by weight dissolved therein was added dropwise over 1 hour, and the mixture was further reacted for 1.5 hours. After completion of the reaction, the reaction mixture was diluted with 125 parts by weight of toluene to obtain an acrylic copolymer solution A-1 having a solid content of 35% by weight.

The viscosity of the obtained acrylic copolymer solution was 730 mPa · s, and the acrylic copolymer had a glass transition temperature (Tg) of −74 ° C. and a weight average molecular weight (Mw) of about 590,000. It was.

Production Example 2 to Production Example 5
Acrylic copolymer solutions A-2 to A-5 were produced in the same manner as in Production Example 1 except that the monomer composition was changed to the monomer composition shown in Table 1. Table 1 shows the viscosity, solid content, glass transition point (Tg), and weight average molecular weight (Mw) of the resulting acrylic copolymer solution.

Production Example 6 Production of Alkylene Oxide-Containing Acrylic Copolymer (B) Four-necked flask equipped with stirring blade, thermometer, nitrogen gas inlet tube, cooler, dropping funnel, 90 parts by weight of t-BMA, containing alkylene oxide group Monomer Methoxypolyethylene glycol methacrylate (alkylene oxide unit is 45) 10 parts by weight, AIBN 0.6 part by weight as a polymerization initiator and ethyl acetate 410 parts by weight, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask 70 ° C
The polymerization reaction was carried out for 6 hours while maintaining the vicinity to prepare an alkylene oxide group-containing acrylic copolymer solution B-1. The acrylic copolymer (B) has a weight average molecular weight of 30,000 and a glass transition temperature (Tg).
Was 15 ° C.

Production Example 7 to Production Example 12
Acrylic copolymer solutions B-2 to B-6 were produced in the same manner as in Production Example 6 except that the monomer composition was changed to the monomer composition shown in Table 1. As B-7, a polypropylene glycol-polyethylene glycol-polypropylene glycol copolymer (weight average molecular weight: 6000, ethylene oxide group content: 50% by weight) was used.
Table 1 shows the viscosity, solid content, glass transition point (Tg), and weight average molecular weight (Mw) of the resulting acrylic copolymer solution.

Acrylic copolymer solutions B-2 to B- were prepared in the same manner as in Production Example 2 except that the monomer composition and the alkylene oxide group-containing monomer composition were changed as shown in Table 1. 6 was produced. Table 2 shows the viscosity, solid content, glass transition point (Tg), and weight average molecular weight (Mw) of the obtained acrylic copolymer solution.

Example 1 Preparation of pressure-sensitive adhesive composition for surface protective film The acrylic copolymer composition (A-1) solution (solid content 34) in a four-necked flask equipped with a stirring blade, a thermometer, a cooler, and a dropping funnel. 0.7% by weight), 100 parts by weight, alkylene oxide group-containing acrylic copolymer (B-1) solution (solid content 20.0% by weight) 0.87 parts by weight, Li (CF ₃ SO ₂ ) ₂ N ( 0.017 parts by weight of LiTFSI manufactured by Morita Chemical Co., Ltd. was charged, and the mixture was stirred for 4.0 hours while maintaining the liquid temperature in the flask at around 25 ° C. to obtain an acrylic copolymer mixed solution. To this, as an isocyanate compound (D), trade name: Aquanate 210 [HMDI type, solid content 100% by weight, isocyanate (NCO) content 16.7% by weight; manufactured by Nippon Polyurethane] 2.4 parts by weight (0.2% as isocyanate) 8 equivalents) was added and sufficiently stirred to obtain a pressure-sensitive adhesive composition solution for an optical member surface protective film shown in Table 3. This pressure-sensitive adhesive composition has a sufficient pot life, and a test surface protective film was prepared according to the method for preparing the test pressure-sensitive adhesive sheet, and the above-described various physical property tests were performed. Table 4 shows the obtained results.

Example 2 to Example 10
A pressure-sensitive adhesive composition for a surface protective film as shown in Table 3 was prepared in the same manner as in Example 1 except that the blending conditions of each Example shown in Table 2 were used instead of the blending conditions of Example 1. . Using this pressure-sensitive adhesive composition, a test surface protective film was prepared according to the above-mentioned test surface protective film preparation method, and the physical properties measured by the test method described above are shown in Table 4.

Comparative Examples 1 to 7
A pressure-sensitive adhesive composition for a surface protective film as shown in Table 3 was prepared in the same manner as in Example 1 except that the mixing conditions of each comparative example shown in Table 2 were used instead of the mixing conditions of Example 1. . Using this pressure-sensitive adhesive composition, a test surface protective film was prepared according to the above-mentioned test surface protective film preparation method, and the physical properties measured by the test method described above are shown in Table 4.

Claims (8)

Acrylic copolymer having 0.1 to 10% by weight of a monomer having a hydroxyl group as a copolymerization component, a weight average molecular weight of 300,000 to 1,000,000, and a glass transition temperature (Tg) of −50 ° C. or lower. For 100 parts by weight of combined (A),
An alkylene oxide chain-containing acrylic system having a weight average molecular weight of 30,000 to 100,000, a glass transition temperature (Tg) of −20 ° C. to 20 ° C., and having 20 or more alkylene oxide chains in the molecule Copolymer (B) 0.05 to 2.0 parts by weight,
And alkali metal salt (C) 0.005 to 0.6 parts by weight
(However, the amount of alkali metal salt (C) does not exceed the amount of acrylic copolymer (B).)
An acrylic pressure-sensitive adhesive composition for a surface protective film. The acrylic pressure-sensitive adhesive composition for a surface protective film according to claim 1, wherein the alkali metal salt is a fluoromethylsulfonyllithium salt. The acrylic for surface protection film according to claim 1 or 2, comprising 0.01 to 2.0 parts by weight of a polyoxyalkylene-modified dimethyl silicon compound with respect to 100 parts by weight of the acrylic copolymer (A). -Based pressure-sensitive adhesive composition. The acrylic adhesive layer for surface protection films formed by bridge | crosslinking the acrylic adhesive composition in any one of Claims 1-4 with an isocyanate crosslinking agent (D). The surface protection of an optical member according to claim 4, wherein the acrylic copolymer (A) is crosslinked with an isocyanate compound (D) in a range of 0.3 to 1.2 equivalents when the total of reactive groups is 1 equivalent. Acrylic adhesive layer for surface protective film for film. An optical member surface protective film obtained by laminating the acrylic pressure-sensitive adhesive layer according to any one of claims 1 to 5 on a polyethylene substrate, wherein the anti-glare polarizing plate has a 180 ° peel at 23 ° C and a peeling rate of 30 m / second. An optical member surface protective film having a peeling voltage at minutes of 0.9 KV or less. The optical member surface protective film according to claim 6, wherein the adhesive force at a peeling rate of 0.3 m / min is 0.05 N / 25 mm or more at an adhesive force of 180 ° peel at 23 ° C. to the optical member. The optical member surface protective film according to claim 6 or 7, wherein an adhesive force at a peeling speed of 30 m / min is 1.2 N / 25 mm or less at an adhesive force of 180 degrees peel at 23 ° C to the optical member.