TW201833601A - Surface protective film and optical member having an adhesive layer thickness less than 2 μm - Google Patents

Abstract

The present invention relates to a surface protective film and an optical member. The present invention provides a surface protective film and an optical member protected by the surface protective film. The surface protective film has a binder layer having a specific thickness. Therefore, for a thin optical member and a display panel, a stage of easily removing the surface protective film is no longer required. The surface protective film of the present invention comprises a base film and an adhesive layer formed on at least one side of the base film. The surface protective film is characterized in that the thickness of the adhesive layer is less than 2 μm.

Description

Surface protection film and optical member

FIELD OF THE INVENTION The present invention relates to a surface protection film and an optical member. In particular, it is used as a polarizing film, a wavelength plate, a retardation plate, an optical compensation film, a reflection sheet, a brightness enhancement film, a protective glass, a protective sheet, used in liquid crystal displays, organic electroluminescence (EL) displays, touch panel displays, etc. A surface protection film used for the purpose of protecting the surface of an optical member, such as a hard coating film, a transparent conductive glass, a transparent conductive film, is useful.

BACKGROUND OF THE INVENTION In recent years, from the aspects of design and portability, the thickness of optical display panels such as liquid crystal displays, organic EL displays, and touch panel displays is progressing. The thickness of optical components used in such displays is required to be reduced. Requirements.

On the other hand, due to the use of such a thin-type optical member, an operation problem in a manufacturing step occurs, and it is necessary to take measures against it. For example, in the manufacture of a liquid crystal display panel, a polarizing film bonded to a liquid crystal cell is formed by first manufacturing a roll form, then unrolling from the roll, and then bonding the liquid crystal cell, or by the following method Forming: cutting to a desired size corresponding to the shape of the liquid crystal cell, and bonding to the liquid crystal cell. In addition, a surface protection film is bonded to the above-mentioned polarizing film for the purpose of preventing damage and stains during transportation (Patent Document 1).

The surface protection film will be peeled and removed at a stage where it is no longer necessary. However, if the liquid crystal display panel is thin, the following problems may occur when the surface protection film with a strong peeling force is peeled off: the liquid crystal display is scratched. The surface protection film cannot be peeled off smoothly, or the liquid crystal display panel or the polarizing film is damaged during peeling. Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2001-305346

SUMMARY OF THE INVENTION Problems to be Solved by the Invention Therefore, in the present invention, intensive studies have been made in view of the above-mentioned circumstances. As a result, an object of the present invention is to provide a surface protection film and an optical member protected by the surface protection film. With the adhesive layer having a specific thickness, by using the surface protective film, it is possible to easily peel off the thin optical member and the display panel at a stage where the surface protective film is no longer needed. The means used to solve the problem

That is, the surface protective film of the present invention is composed of a base film and an adhesive layer, and the adhesive layer is formed on at least one side of the base film. The surface protective film is characterized in that the thickness of the adhesive layer is less than 2 μm.

In the surface protection film of the present invention, the 90 ^° peeling initial peeling force of the triacetam cellulose film at 23 ° C. and 50% RH is preferably 1 N / 50 mm or less.

In the surface protection film of the present invention, the thickness of the substrate film is preferably 20 μm or more.

In the surface protection film of the present invention, it is preferable that the adhesive layer contains at least one selected from the group consisting of an acrylic adhesive, a polyurethane adhesive, and a polysiloxane adhesive.

The optical member of the present invention is preferably protected by the surface protection film.

In the optical member of the present invention, the optical member is preferably a polarizing film including a polarizer, and the thickness of the polarizer is 8 μm or less. Invention effect

In the present invention, by using a surface protection film having an adhesive layer having a specific thickness, the surface protection film can be easily peeled after being adhered to a thin optical member or a display panel at a stage where the surface protection film is no longer needed, which is useful.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

<Overall Structure of Surface Protection Film> The surface protection film disclosed here is generally in the form of an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film, etc., and is particularly suitable as an optical member (such as a polarizing film, a wavelength, etc.). A surface protective film that protects the surface of an optical member during processing or transportation, such as an optical member used as a constituent element of a liquid crystal display panel, an optical member used in a touch panel display such as a hard coat film, and the like during processing or transportation. The adhesive layer in the surface protection film is typically formed continuously, but is not limited to this form. For example, the adhesive layer may be an adhesive layer formed in a regular or irregular pattern such as a dot or a stripe. In addition, the surface protective film disclosed herein may be in a roll shape or in a paper shape (sheet-like shape).

A typical configuration example of the surface protection film disclosed here is schematically shown in FIG. 1. The surface protection film 1 includes a base film (for example, a polyester film) 12 and an adhesive layer 20 provided on one side of the base film 12. The surface protection film 1 is used by adhering the adhesive layer 20 to an adherend (a protection target, for example, the surface of a transparent protection film 30 on the surface of an optical member such as a polarizing film). The surface protection film 1 before use (that is, before being adhered to the adherend) may be a separator (release liner) on which the surface of the adhesive layer 20 (adhesive surface with the adherend) is a release surface at least on the adhesive layer 20 side. Pad) protected form. Alternatively, the surface protection film 1 may be wound into a roll shape, whereby the adhesive layer 20 is in contact with the back surface of the base film 12 and the surface is protected.

In addition, as shown in FIG. 1, the polarizing film 2 may be protected by being adhered to the surface of the transparent protective film 30 constituting the polarizing film 2 through an adhesive layer 20 constituting the surface protective film 1. It should be noted that, the transparent protective film 30 and the polarizer 40 may form a polarizing film through the adhesive layer 22. In addition, the transparent protective film 31 may be pasted on the surface of the polarizer 40 on which the transparent protective film 30 is pasted, and the transparent protective film 31 may be pasted through the adhesive layer 23, and the first adhesive layer 21 may be further laminated. It laminates other optical members and the like.

<Base film of surface protection film> The surface protection film of the present invention is characterized by having a base film. In the technology disclosed herein, the resin material constituting the base film can be used without particular limitation, but it is preferably used, for example, transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, flexibility, and dimensional stability. Resin material with excellent properties such as properties. In particular, since the base film has flexibility, the adhesive composition can be applied by a roll coater or the like, and can be wound into a roll shape, which is useful.

As the substrate film (substrate, support), for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polybutylene terephthalate can be preferably used. Polyester polymers such as glycol esters; cellulose polymers such as diacetyl cellulose and triethyl cellulose; polycarbonate polymers; acrylic polymers such as polymethyl methacrylate; etc. A plastic film made of a resin material (a main component of the resin component, typically a component that accounts for 50% by mass or more) is used as the substrate film. As other examples of the resin material, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; polyethylene, polypropylene, cyclic or Examples of resin materials include olefin polymers such as olefins such as polyolefins and ethylene-propylene copolymers; vinyl chloride polymers; nylon 6, nylon 6,6, and aromatic polyamines; and the like. As another example of the resin material, fluorene-based polymers, fluorene-based polymers, polyether fluorene-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, and ethylene Alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aryl ester polymers, polyoxymethylene polymers, epoxy polymers, etc. It may also be a base film comprising a blend of two or more of the aforementioned polymers.

As the substrate film, a plastic film made of a transparent thermoplastic resin material can be preferably used. Among the above-mentioned plastic films, a case where a polyester film is used is a more preferable aspect. Here, the polyester film refers to a polymer having an ester bond, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, and the like. The polymer material of the skeleton (polyester resin) is a film whose main resin component is. The polyester film is excellent in optical characteristics, dimensional stability, and the like, and is preferably used as a base film of a surface protection film.

Various additives, such as an antistatic agent, an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.), can be mix | blended with the resin material which comprises the said base film as needed. For example, a known or customary surface treatment such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation treatment, an acid treatment, an osmosis treatment, and application of a primer may be performed. Such a surface treatment may be, for example, a treatment for improving the adhesion between the substrate film and the adhesive layer (anchorability of the adhesive layer).

The surface protection film of the present invention may use an antistatic-treated plastic film as the substrate film. The use of the above-mentioned base film is preferable because it is possible to suppress the charging of the surface protection film itself at the time of peeling. In addition, the base film is a plastic film. By performing an antistatic treatment on the plastic film, it is possible to reduce the charge of the surface protection film itself and to obtain a base film with excellent antistatic ability to the adherend. In addition, there is no restriction | limiting in particular as a method of providing an antistatic function, A conventionally well-known method can be used, For example, the coating of the antistatic resin or conductive polymer containing an antistatic agent and a resin component, and containing A method of a conductive resin of a conductive material; a method of vapor-depositing or plating a conductive material; a method of kneading an antistatic agent; and the like.

The thickness of the substrate film is preferably 20 μm or more, more preferably 20 μm to 200 μm, still more preferably 25 μm to 150 μm, particularly preferably 30 μm to 100 μm, and most preferably 50 μm to 80 μm. When the thickness of the substrate film is within the above range, it is preferable because the polarizing film and the optical member have good transportability and adhesion properties. In particular, when it is used for a thin optical member having a thickness of 100 μm or less, it is preferable to use a base film having a thickness of 50 μm or more in terms of the thickness of the base film in order to ensure transportability and adhesion.

The surface protection film disclosed herein may be implemented in a manner including other layers in addition to the base film and the adhesive layer. Examples of the other layers include an undercoat layer (anchor layer) and the like that improve the anchoring property of the antistatic layer or the adhesive layer.

<Adhesive layer of surface protective film> The surface protective film of the present invention has an adhesive layer on at least one side of the substrate film, and the adhesive layer is formed of an adhesive composition. As the adhesive composition, as long as it is Adhesive substances can be used without particular restrictions. As the adhesive composition, for example, an acrylic adhesive, a polyurethane adhesive, a synthetic rubber adhesive, a natural rubber adhesive, a polysiloxane adhesive, or a polyester adhesive can be used (containing) And polyether-based adhesives, among them, more preferably at least one selected from the group consisting of acrylic-based adhesives, polyurethane-based adhesives, and polysiloxane-based adhesives, and it is particularly preferred to use (contain) the use of An acrylic adhesive as a (meth) acrylic polymer as an adhesive polymer.

<Acrylic Adhesive> When an acrylic adhesive is used in the adhesive layer, a (meth) acrylic polymer that is an adhesive polymer constituting the acrylic adhesive is used as a raw material constituting the acrylic polymer. As the monomer, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used as the main monomer. As the (meth) acrylic monomer, one kind or two or more kinds can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the peeling force (adhesive force) to the adherend (protected body) can be easily controlled to be low, and light weight can be obtained. A surface protective film having excellent peelability and re-peelability. It should be noted that the (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to an acrylate and / or a methyl group. Acrylate.

Specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) N-butyl acrylate, secondary butyl (meth) acrylate, tertiary butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethyl (meth) acrylate Hexyl ester, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, ( Isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like.

Among them, examples of the surface protective film of the present invention include n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-octyl (meth) acrylate. Ester, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) () (Meth) acrylic acid having an alkyl group having 4 to 14 carbon atoms such as n-dodecyl acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate Monomers are suitable as raw material monomers. In particular, by using a (meth) acrylic monomer having an alkyl group having 6 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) to the adherend to be low, and the surface is excellent in re-peelability. Protective film.

In particular, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms is preferably contained in an amount of 50% by mass or more based on 100% by mass of the total monomer components constituting the (meth) acrylic polymer. It is more preferably 80% by mass or more, still more preferably 85% by mass to 99.9% by mass, and most preferably 90% by mass to 99% by mass. If it is less than 50% by mass, the appropriate wettability of the adhesive composition or the cohesive force of the adhesive layer is deteriorated, which is not preferable.

Moreover, in the adhesive composition of this invention, it is preferable that the said (meth) acrylic-type polymer contains a hydroxyl-containing (meth) acrylic-type monomer as a raw material monomer. These hydroxyl-containing (meth) acrylic monomers can be used alone or in combination of two or more. By using the above-mentioned hydroxyl-containing (meth) acrylic monomer, it is easy to control the cross-linking of the adhesive composition and the like, and further it is easy to control the balance between improvement in flow-based wettability and reduction in peeling force (adhesive force) during peeling.

Examples of the hydroxy-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4-hydroxylauryl (meth) acrylate Methyl cyclohexyl) methyl ester, N-hydroxymethyl (meth) acrylamide and the like. In particular, by using a hydroxyl-containing (meth) acrylic monomer having an alkyl group having 4 or more carbon atoms, light peeling at the time of high-speed peeling becomes easy, which is preferable.

With respect to 100% by mass of the total monomer components constituting the (meth) acrylic polymer, the hydroxy-containing (meth) acrylic monomer is preferably contained in an amount of 25% by mass or less, and more preferably 20% by mass or less. It is preferably 0.1% to 15% by mass, and most preferably 1% to 10% by mass. When it is in the said range, since it is easy to control the balance of the wettability of an adhesive composition and the cohesive force of the obtained adhesive layer, it is preferable.

In addition, as another polymerizable monomer component, for the reason that it is easy to achieve a balance in adhesive properties, the glass transition temperature and the peelability of the (meth) acrylic polymer can be adjusted within a range that does not impair the effects of the present invention. Polymerizable monomers such that the Tg is 0 ° C or lower (usually -100 ° C or higher).

As the (meth) acrylic polymer, other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and the hydroxyl-containing (meth) acrylic monomer described above As the polymerizable monomer, a carboxyl group-containing (meth) acrylic monomer can be used. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress an increase in adhesion of the surface protection film (adhesive layer) with time, and it is excellent in re-peelability, increase in adhesion prevention property, and workability. In addition, adhesion Both of the agent layers are excellent in cohesive force and shear force, and are therefore preferred.

Examples of the carboxyl group-containing (meth) acrylic monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, and carboxypentyl (meth) acrylate.

The content of the carboxyl group-containing (meth) acrylic monomer is preferably 10% by mass or less, and more preferably 0.005% to 10% by mass based on 100% by mass of the total monomer components constituting the (meth) acrylic polymer. It is more preferably 0.01% by mass to 8% by mass, and most preferably 0.01% by mass to 5% by mass. When it is in the said range, since it is easy to control the balance of the wettability of an adhesive composition and the cohesive force of the obtained adhesive layer, it is preferable.

In addition, as the (meth) acrylic polymer, the (meth) acrylic monomer having a C1-C14 alkyl group, a hydroxyl-containing (meth) acrylic monomer, and a carboxyl group are used. The polymerizable monomer other than the (meth) acrylic monomer can be used without particular limitation as long as it is within a range that does not impair the characteristics of the present invention. Suitable components such as cyano-containing monomers, vinyl ester monomers, and aromatic vinyl monomers can be used as appropriate to improve cohesion and heat resistance; fluorenamine-containing monomers, fluorenimine-containing monomers, and amine-containing monomers Monomer, epoxy-containing monomer, N-acrylfluorenyl A component having a functional group that functions as a crosslinking point, such as a phthaloline and a vinyl ether monomer. Among them, it is preferable to use a cyano-containing monomer, a fluorenimine-containing monomer, a fluorenimine-containing monomer, an amine-containing monomer, and an N-acrylfluorene group. Nitrogen-containing monomers, such as phospholine. The use of a nitrogen-containing monomer is useful because a surface protective film having more excellent shear force can be obtained. These polymerizable monomers can be used alone or in combination of two or more.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the amidino group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropylmethacrylamine, diacetoneacrylamide, and the like.

Examples of the fluorenimine-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, itaconicimide, and the like.

Examples of the amine-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and N, N-di (meth) acrylate Methyl aminopropyl esters and the like.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, and vinyl laurate.

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

Examples of the epoxy-group-containing monomer include epoxy (meth) acrylate, methyl glycid (meth) acrylate, and allyl glycid ether.

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

In the present invention, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and the hydroxyl group-containing monomer are added to 100% by mass of the total monomer components constituting the (meth) acrylic polymer. The polymerizable monomer other than the (meth) acrylic monomer and the carboxyl group-containing (meth) acrylic monomer is preferably 0 to 50% by mass, and more preferably 0 to 20% by mass. In order to obtain desired characteristics, the other polymerizable monomers described above may be appropriately adjusted.

The (meth) acrylic polymer may further contain a reactive monomer containing an alkylene oxide group as a monomer component. By using the above monomers, it is easy to achieve both adhesion and peelability to the adherend.

The (meth) acrylic polymer preferably has a weight-average molecular weight (Mw) of 100,000 to 3 million, more preferably 200,000 to 2 million, still more preferably 300,000 to 950,000, and most preferably 300,000. ~ 750,000. When the weight average molecular weight is less than 100,000, there is a tendency that a paste residue tends to occur because the cohesive force of the adhesive layer is reduced. On the other hand, when the weight-average molecular weight exceeds 3 million, the fluidity of the polymer is reduced, and wetting of the adherend (for example, a polarizing film) is insufficient, and it becomes a layer of an adhesive between the adherend and the surface protection film. The cause of the bulge caused by the tendency. In addition, a weight average molecular weight means the weight average molecular weight measured by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C or lower, and more preferably -10 ° C or lower (usually -100 ° C or higher). When the glass transition temperature is higher than 0 ° C, the polymer is difficult to flow, and for example, there is a tendency that the wetting of the polarizing film is insufficient and a bulge occurs between the polarizing film and the adhesive layer of the surface protective film. In particular, by adjusting the glass transition temperature to -50 ° C or lower, it is easy to obtain an adhesive layer having excellent wettability and light peelability to a polarizing film. In addition, the glass transition temperature of a (meth) acrylic-type polymer can be adjusted in the said range by changing the monomer component and composition ratio used suitably.

The method of polymerizing the (meth) acrylic polymer is not particularly limited, and it can be polymerized by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. However, from the viewpoint of workability, especially for adherends ( In view of characteristics such as low pollution resistance of the protected object, solution polymerization is a more preferred method. The obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

<Polyurethane-based Adhesive> When a polyurethane-based adhesive is used for the adhesive layer, any suitable polyurethane-based adhesive can be used. Examples of such a polyurethane-based adhesive include a polyurethane-based adhesive containing a polyurethane-based polymer, which is an adhesive polymer obtained by reacting a polyol and a polyisocyanate compound. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate.

<Polysiloxane type adhesive> When a polysiloxane type adhesive is used for the said adhesive layer, any suitable polysiloxane type adhesive can be used. As such a polysiloxane-based adhesive, a polysiloxane-based adhesive obtained by blending or aggregating a polysiloxane-based polymer as an adhesive polymer can be preferably used.

Examples of the polysiloxane-based adhesive include addition reaction-curable polysiloxane-based adhesives and peroxide-curable polysiloxane-based adhesives. Among these polysiloxane-based adhesives, an addition reaction-curable polysiloxane-based adhesive is preferred because it does not use a peroxide (benzidine peroxide or the like) and does not generate decomposition products.

As the curing reaction of the addition reaction-curable polysiloxane-based adhesive, for example, in the case of obtaining a polyalkylsiloxane-based adhesive, in general, a platinum-based catalyst can be used to make a polyalkylhydrosiloxane. Method for curing alkane composition.

<Crosslinking agent> In the surface protection film of this invention, it is preferable that the said adhesive composition contains a crosslinking agent. In the present invention, an adhesive layer can be formed using the above-mentioned adhesive composition. For example, when the adhesive composition is an acrylic adhesive containing the (meth) acrylic polymer, the constitutional unit, the composition ratio, and the crosslinking agent of the (meth) acrylic polymer are appropriately adjusted. Selection and addition ratio, etc., and cross-linking can provide a surface protection film (adhesive layer) with more excellent heat resistance.

As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine-based resin, an aziridine derivative, a metal chelate compound, and the like can be used. In particular, the use of an isocyanate compound is a preferred embodiment. These compounds may be used alone or in combination of two or more.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), and dimer acid diisocyanate; and cyclopentyl diisocyanate. Alicyclic isocyanates such as isocyanate, cyclohexyl diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis (isocyanatomethyl) cyclohexane; 2,4-toluene diisocyanate, 4 , 4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI) and other aromatic isocyanates; Urea bond, biuret bond, isocyanurate bond, uretdione (uretdione) bond, urea bond, carbodiimide bond, uretonimine bond, two A polyisocyanate modified product obtained by modifying the isocyanate compound with a triketone bond or the like. Examples of commercially available products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (above manufactured by Mitsui Chemicals), Sumidule T80, Sumidule L, Desmodur N3400 (above, Sumika Bayer Polyurethane (Sumika) Bayer Urethane), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (the above are manufactured by Tosoh Corporation), etc. These isocyanate compounds may be used singly or in combination of two or more kinds, and a bifunctional isocyanate compound and a trifunctional or more isocyanate compound may be used in combination. By using a cross-linking agent in combination, it is possible to achieve both adhesiveness and rebound resilience (adhesiveness to curved surfaces), and a surface protective film having more excellent adhesive reliability can be obtained.

Examples of the epoxy compound include N, N, N ', N'-tetraepoxypropylm-xylylenediamine (trade name TETRAD-X, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and the like.

Examples of the melamine-based resin include hexamethylolmelamine. Examples of the aziridine derivative include, for example, commercially available products under the trade names HDU, TAZM, and TAZO (the above are manufactured by Kakuya Kogyo).

Examples of the metal chelate compound include aluminum, iron, tin, titanium, and nickel as the metal component, and examples of the chelate component include acetylene, acetamidine methyl acetate, and ethyl lactate.

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, with respect to 100 parts by mass of the (meth) acrylic polymer. It is more preferably 0.5 to 10 parts by mass, and most preferably 1 to 6 parts by mass. When the content is less than 0.01 parts by mass, the cross-linking formation by the cross-linking agent becomes insufficient, and the cohesive force of the obtained adhesive layer tends to be small, and sufficient heat resistance may not be obtained, and This is the cause of the sticky residue. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, and the fluidity is reduced, and there is a tendency that the wetting of the adherend (such as a polarizing film) is insufficient, and the adherence and adhesion of the adherend Causes of bulges between agent layers (adhesive composition layers). These crosslinking agents may be used alone or in combination of two or more.

The said adhesive composition may further contain the crosslinking catalyst for making the said arbitrary crosslinking reaction more efficient. As the cross-linking catalyst, for example, tin-based catalysts such as dibutyltin dilaurate, dioctyltin dilaurate; tris (acetamidineacetone) iron (acetamidineacetonate iron (III)), Tris (hexane-2,4-dione) iron, tris (heptane-2,4-dione) iron, tris (heptane-3,5-dione) iron, tris (5-methyl Hexane-2,4-diketone) iron, tris (octane-2,4-diketone) iron, tris (6-methylheptane-2,4-diketone) iron, tris ( 2,6-dimethylheptane-3,5-diketone) iron, tris (nonane-2,4-diketone) iron, tris (nonane-4,6-diketone) iron, Tris (2,2,6,6-tetramethylheptane-3,5-dione) iron, tris (tridecane-6,8-dione) iron, tris (1-phenylbutane -1,3-diketone) iron, tris (hexafluoroacetoneacetone) iron, tris (ethylacetate) iron, tris (ethylacetate) propyl, tris (ethylacetate) isopropyl Ester) iron, tris (n-butylacetate) iron, tris (secondary acetic acid acetate) iron, tris (tributylacetate) iron, tris (methylacetate) iron, tris (Ethyl acetate) iron, tris (n-propylpropionate) iron, tris (isopropylpropionate) iron, tris (n-butylpropionate) iron, tris (propyl (Ethyl butyl acetate) iron, tris (trimethylpropionate) iron, tris (benzylacetate) iron, tris (dimethylmalonate) iron, tris (malonate) Ethyl) iron catalysts such as iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, and ferric chloride. These crosslinking catalysts may be used singly or in combination of two or more kinds.

The content of the cross-linking catalyst is not particularly limited. For example, it is preferably about 0.0001 to about 1 part by mass, and more preferably 0.001 to 0.5 parts by mass based on 100 parts by mass of the (meth) acrylic polymer. When it is in the said range, the speed of a crosslinking reaction when forming an adhesive layer is fast, and the pot life of an adhesive composition becomes long, and it is a preferable aspect.

The adhesive composition may contain an alkylene oxide (AO) group-containing compound. This makes it possible to improve the wettability to the adherend, improve the adherence to the adherend, and easily suppress the incorporation of bubbles and the like generated during the attachment.

Specific examples of the alkylene oxide (AO) group-containing compound include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, Polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkylphenyl ether, polyoxyalkylene alkyl ether, polyoxyalkylene allyl ether, polyoxyalkylene Non-ionic surfactants such as alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether, polyalkylene glycol dialkyl ester, polyalkylene glycol diaryl ester; poly Oxyalkylene alkyl ether sulfate, polyoxyalkylene allyl ether sulfate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether sulfate, Anionic surfactants such as polyoxyalkylene alkylallyl phenyl ether sulfate, polyoxyalkylene alkyl phenyl ether phosphate, and polyoxyalkylene chain (polyalkylene) Oxide chain) cationic or amphoteric surfactants, polyether compounds with polyoxyalkylene chains (and derivatives thereof), esterification with polyoxyalkylene chains Was (and including derivatives thereof), acrylic compound having a polyoxyalkylene chain alkylene group (including derivatives thereof as well) and the like. In addition, a polyoxyalkylene chain-containing monomer may be blended into the acrylic polymer as a polyoxyalkylene chain-containing compound. The polyoxyalkylene chain-containing compound may be used alone or in combination of two or more kinds.

Specific examples of the ether compound having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG) -polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, PEG-PPG-PEG block copolymer and the like. Examples of the derivative of the ether compound having a polyoxyalkylene chain include an oxypropylene group-containing compound (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) having an etherified terminal, and Oxypropylated compounds (such as terminal acetylated PPG, etc.) having acetylated ends, and the like. Moreover, as a specific example of the said ester compound which has a polyoxyalkylene chain, the ester compound which has an oxyalkylene group is mentioned. From the viewpoint of coordination of an ionic compound, as the oxyalkylene group, the number of addition mols of the oxyalkylene unit is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20. Specific examples include diethylene glycol dibenzoate, triethylene glycol dibenzoate, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, and poly (ethylene glycol) dibenzoate. Propylene glycol dibenzoate, polyethylene glycol-2-ethylhexanoate benzoate, and the like. Moreover, as a specific example of the said acrylic compound which has a polyoxyalkylene chain, the (meth) acrylate polymer which has an oxyalkylene group is mentioned. From the viewpoint of coordination of an ionic compound, as the oxyalkylene group, the number of moles of addition of the oxyalkylene unit is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20. The terminal of the oxyalkylene chain may be a hydroxyl group itself or substituted with an alkyl group, a phenyl group, or the like.

The (meth) acrylate polymer having an oxyalkylene group is preferably a polymer containing a (meth) acrylic acid alkylene oxide as a monomer unit (component), and the (meth) acrylic acid alkylene oxide is oxidized. Specific examples of the substance include, as the ethylene glycol group-containing (meth) acrylate, for example, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (methyl Type) methoxy polyethylene glycol (meth) acrylate type, such as acrylate; ethoxy diethylene glycol (meth) acrylate, ethoxy triethylene glycol (meth) acrylate, etc. Type polyethylene glycol (meth) acrylate type; butoxy polyethylene glycol (meth) acrylate such as butoxydiethylene glycol (meth) acrylate, butoxytriethylene glycol (meth) acrylate Group) acrylate type; phenoxy polyethylene glycol (meth) acrylate type such as phenoxydiethylene glycol (meth) acrylate, phenoxytriethylene glycol (meth) acrylate; 2 -Ethylhexyl polyethylene glycol (meth) acrylate, nonylphenol polyethylene glycol (meth) acrylate type; methoxy polypropylene glycol (meth) such as methoxy dipropylene glycol (meth) acrylate ) Acrylate type and so on.

In addition, as the monomer unit (component), other monomer units (components) other than the (meth) acrylic acid alkylene oxide may be used. Specific examples of the other monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, secondary butyl (meth) acrylate, (formyl) Base) tert-butyl acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, (meth) Isooctyl acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecane (meth) acrylate Acrylates and / or methacrylates having alkyl groups having 1 to 14 carbon atoms, such as n-tridecyl (meth) acrylate and n-tetradecyl (meth) acrylate, and the like.

In addition, as other monomer units (components) other than the (meth) acrylic acid alkylene oxide, a carboxyl group-containing (meth) acrylate, a phosphate group-containing (meth) acrylate, and a cyanide may be suitably used. (Meth) acrylates, vinyl esters, aromatic vinyl compounds, acid anhydride-containing (meth) acrylates, hydroxyl-containing (meth) acrylates, amido-containing (meth) acrylates, Amino (meth) acrylate, epoxy-containing (meth) acrylate, N-propenyl Phenols, vinyl ethers, etc.

As the number-average molecular weight (Mn) of the alkylene oxide (AO) group-containing compound, a compound having a molecular weight of 50,000 or less is suitable, preferably 200 to 30,000, more preferably 200 to 10,000, and usually a preferred amount Compound having an average molecular weight of 200 to 5000. When the Mn ratio is too large than 50,000, the compatibility with the acrylic polymer decreases, and the adhesive layer tends to whiten. When the Mn ratio is more than 200, contamination due to the polyoxyalkylene compound may easily occur. In addition, Mn here means the polystyrene conversion value obtained by gel permeation chromatography (GPC).

The content of the alkylene oxide (AO) group-containing compound is not particularly limited. For example, it may be set to about 0.005 parts by mass to about 20 parts by mass based on 100 parts by mass of the (meth) acrylic polymer. It is 0.01 to 15 parts by mass, more preferably 0.05 to 10 parts by mass, and most preferably 0.1 to 4 parts by mass. When the blending amount is too small, the wettability effect on the adherend is reduced. When the blending amount is too large, contamination due to the polyoxyalkylene compound is likely to occur, and the optical characteristics of the optical member may be impaired.

In addition, the above-mentioned adhesive composition may contain other well-known additives. For example, powders such as lubricants, colorants, and pigments, plasticizers, tackifiers, low-molecular-weight polymers, and the like may be appropriately added according to the intended use. Surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, antistatic agents, cross-linking retarders, inorganic or organic fillers, metal powders, Particles, foils, etc.

<Adhesive layer and surface protection film> The surface protection film of the present invention is a film obtained by forming the above-mentioned adhesive layer on at least one side of the substrate film. In this case, the crosslinking of the adhesive composition is usually performed by applying an adhesive composition. It can also be used to form a binder containing a crosslinked adhesive composition on a separator provided with a release agent layer of polysiloxane, fluorine-containing type, long-chain alkyl type, or fatty acid amide type. The agent layer is transferred to a substrate film or the like.

The method for forming the adhesive layer on the base film is not particularly limited. For example, it can be produced by applying the above-mentioned adhesive composition (solution) to the base film, drying and removing the polymerization solvent, etc. An adhesive layer is formed on the film. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the adhesive layer or adjusting the crosslinking reaction. In addition, when the adhesive composition is coated on a substrate film to prepare a surface protection film, one or more solvents other than a polymerization solvent may be newly added to the adhesive composition to enable uniform coating on the substrate film. on.

In addition, as a method for forming the adhesive layer when producing the surface protective film of the present invention, a known method used in the production of adhesive tapes can be used. Specifically, for example, a roll coating method, a gravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method, an extrusion coating method using a mouth pattern coater, and the like can be cited.

In the surface protection film of the present invention, the thickness of the adhesive layer is less than 2 μm, preferably 0.1 μm or more and less than 2 μm, more preferably 0.2 μm to 1.5 μm, still more preferably 0.4 μm to 1.2 μm, and particularly preferably 0.5 μm to 1 μm. When the thickness of the adhesive layer is within the above range, the initial peeling force will be low, and it is preferable that the surface protective film can be easily peeled off after the surface protective film is no longer needed after being adhered to a thin optical member or a display panel. of.

For the adhesive layer, the shear storage modulus (G ') at 23 ° C is preferably 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁷ Pa, and more preferably 1.0 × 10 ⁵ Pa to 5.0 × 10 ⁶ Pa It is more preferably 3.0 × 10 ⁵ Pa to 5.0 × 10 ⁶ Pa. By adjusting to the above-mentioned range, it is possible to secure the adhesion to the surface of the adherend while suppressing the initial peeling force to a low level, and it is possible to easily adhere to the surface, which is a preferred embodiment.

In addition, the 90 ^° peeling initiation peeling force of the surface protective film (adhesive layer) on the triethyl cellulose film (polarizing film) at 23 ° C. and 50% RH is preferably 1 N / 50 mm or less, and more preferably 0.05. N / 50mm to 1N / 50mm, more preferably 0.1N / 50mm to 0.95N / 50mm, and particularly preferably 0.2N / 50mm to 0.9N / 50mm. When the initial peeling force exceeds 1 N / 50 mm, peeling resistance is applied when the surface protective film is peeled from the polarizing film by a pick-up tape, and peeling is difficult, which is not preferable.

The surface protection film of the present invention preferably has a total thickness of 20 μm to 400 μm, more preferably 30 μm to 200 μm, still more preferably 40 μm to 150 μm, and particularly preferably 50 μm to 100 μm. When it is in the said range, it is a preferable aspect which is excellent in adhesive characteristics (removability, adhesiveness, etc.), workability, and an external appearance characteristic. In addition, the said total thickness means the sum total of the thickness of all layers, when a base film, an adhesive layer, and other layers exist.

<Separator> On the surface protection film of the present invention, a separator can be bonded to the surface of the adhesive layer as needed for the purpose of protecting the adhesive surface of the adhesive layer.

As a material constituting the separator, there are paper and a plastic film. From the viewpoint of excellent surface smoothness, a plastic film is preferably used. The film is not particularly limited as long as it can protect the adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, and polymethylpentene films. , Polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like.

The thickness of the separator is usually about 5 μm to about 200 μm, and preferably about 10 μm to about 100 μm. When it is in the said range, it is preferable since it is excellent in the adhesiveness property with respect to an adhesive bond layer, and peeling workability from an adhesive bond layer. If necessary, the above-mentioned separator may be subjected to a mold release and antifouling treatment using a release agent such as polysiloxane, fluorine-containing type, long-chain alkyl type or fatty ammonium type, silicon dioxide, or the like, or Antistatic treatments such as coating type, kneading type, and vapor deposition type.

<Optical member> It is preferable that the optical member of this invention is protected by the said surface protection film. The surface protection film can be used for surface protection applications such as processing, transportation, and shipping, and is useful for protecting the surface of the optical member (polarizing film, etc.). Especially for a thin optical member (such as a polarizing film) or a display panel, the surface protective film can be easily peeled off at a stage where the surface protective film is no longer needed, which is very useful.

The optical member of the present invention is a polarizing film including a polarizer, and the thickness of the polarizer is preferably 8 μm or less. The thickness of the polarizer is as thin as 8 μm or less, which is useful for optical members (polarizing films) that require thinning in recent years, and is a preferred embodiment.

<Polarizing Film> As the polarizing film, a polarizing film having a polarizer, a transparent protective film laminated on at least one side of the polarizer, and a first adhesive layer laminated on at least one side of the polarizing film can be used.

<Polarizer> As the polarizer, a material using a polyvinyl alcohol resin can be used. Examples of the polarizer include adsorption of iodine or dichroism on hydrophilic polymer films such as polyvinyl alcohol-based films, partially methylated polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. A film obtained by uniaxially stretching a dichroic substance such as a dye, a polyene oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride, and the like. Among these, a polarizer containing a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine to perform dyeing, and stretching the original length to 3 ~ 7 times. It may contain boric acid, zinc sulfate, zinc chloride, etc. as needed, and may be immersed in the aqueous solution, such as potassium iodide. If necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, in addition to cleaning dirt and anti-blocking agents on the surface of the polyvinyl alcohol-based film, it also has the effect of preventing uneven dyeing and unevenness by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, or stretching may be performed simultaneously with dyeing, or dyeing may be performed with iodine after stretching. Stretching may also be performed in an aqueous solution or a water bath such as boric acid or potassium iodide.

From the viewpoint of thinning, the thickness of the polarizer is preferably 8 μm or less, more preferably 7 μm or less, and even more preferably 6 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more. Such a thin polarizer has small thickness unevenness, excellent visibility, and small dimensional change, and therefore has excellent durability against thermal shock. Examples of thin polarizers include Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, and International Publication No. 2014/077599. The thin polarizers described in International Publication No. 2014/077636, etc., or the thin polarizers obtained by the manufacturing methods described in them.

The above-mentioned polarizer is preferably such that the optical characteristics represented by the single-plate transmittance (carcass transmittance) T and the degree of polarization P satisfy the following formula P>-(100.929T-42.4-1) × 100 (where T <42.3) or It is constituted with a condition of P ≧ 99.9 (where T ≧ 42.3). A polarizer configured to satisfy the above conditions uniquely has the performance required as a display for a liquid crystal television using a large display element. Specifically, the contrast is 1000: 1 or more and the maximum brightness is 500cd / m ² or more. For other uses, for example, it is bonded to the visual recognition side of the organic EL unit.

As the above-mentioned thin polarizer, it is preferable to use a method that can stretch at a high magnification and improve polarizing performance even in a manufacturing method including a step of stretching in a laminated state and a step of dyeing. The thin polarizer obtained by the manufacturing method described in Japanese Patent No. 4751486, Japanese Patent No. 4751481, and Japanese Patent No. 4815544, which includes a step of stretching in an aqueous boric acid solution, is particularly preferably obtained by Japanese Patent No. The thin polarizer obtained by the manufacturing method described in the specification No. 4751481 and the specification of Japanese patent No. 4815544 including the step of assisting the stretching in air before stretching in an aqueous boric acid solution. These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a stretching resin substrate film in a state of a laminate, and a step of dyeing. . According to this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without being unfavorable such as breakage caused by stretching by being supported by the resin substrate film for stretching.

(Transparent protective film) The material constituting the transparent protective film is not particularly limited, and materials having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropic properties, and the like are preferred. Examples include: polyester polymers such as polyethylene terephthalate or polyethylene naphthalate; cellulose polymers such as diacetyl cellulose or triethyl cellulose; polymethyl Acrylic polymers such as methyl acrylate; styrene polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin); polycarbonate polymers. Other examples include polyethylene, polypropylene, and Polyolefin polymers such as olefins, polyolefin polymers such as ethylene-propylene copolymers, vinyl chloride polymers, fluorene polymers such as nylon or aromatic polyamines, fluorene polymers, and fluorene polymers Polymers, polyether ether polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aryl esters As the polymer forming the above-mentioned transparent protective film, a polymer such as a polymer, a polyoxymethylene polymer, an epoxy polymer, or a blend of the above-mentioned polymers is exemplified. These transparent protective films are usually attached to a polarizer through an adhesive layer. It should be noted that the transparent protective film may contain one or more of any suitable additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-colorants, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

The content of the thermoplastic resin in the transparent protective film is preferably 50% to 100% by mass, more preferably 50% to 99% by mass, still more preferably 60% to 98% by mass, and particularly preferably 70% to 97% by mass. quality%. When the content of the thermoplastic resin in the transparent protective film is 50% by mass or less, the high transparency and the like that the thermoplastic resin originally possessed may not be sufficiently expressed.

The thickness of the transparent protective film can be appropriately determined, but in general, it is preferably 5 μm to 50 μm, and more preferably 5 μm to 45 μm in terms of workability such as strength and handleability, thinness, and the like.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, or an anti-glare layer may be provided on the surface of the non-adhesive polarizer of the transparent protective film. It should be noted that the functional layers such as the hard coating layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer, or the anti-glare layer may be provided on the transparent protective film itself or separately from the transparent protective film.

The transparent protective film and the polarizer are laminated via an intermediate layer (intermediate layer) such as an adhesive layer, an adhesive layer, an undercoat layer (primer layer), and the like. At this time, it is desirable to laminate the two without an air gap through the intermediate layer.

The adhesive layer is formed of an adhesive. The type of the adhesive is not particularly limited, and various adhesives can be used. The adhesive layer is not particularly limited as long as it is optically transparent. As the adhesive, various types of adhesives, such as water-based, solvent-based, hot-melt, and active energy ray-curable, can be used, and water-based is preferred. Adhesive or active energy ray-curable adhesive.

Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. The aqueous adhesive is generally used in the form of an adhesive containing an aqueous solution, and is usually obtained by containing 0.5 to 60% by weight of a solid content.

The active energy ray-curable adhesive is an adhesive that is cured by active energy rays such as electron rays and ultraviolet (radical-curable, cation-curable), and can be used, for example, as an electron-ray-curable or ultraviolet-curable. . As the active energy ray-curable adhesive, for example, a photo-radical-curable adhesive can be used. In the case where a photo-radical-curable active energy ray-curable adhesive is used as the UV-curable, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

The application method of the above adhesive can be appropriately selected according to the viscosity of the adhesive and the target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct gravure coater, reverse gravure coater, or offset gravure coater), a bar reverse coater, a roll coater, and a die coater. Machine, bar coater, bar coater, etc. In addition, a method such as a dipping method can be appropriately used in the application.

In addition, when the above-mentioned adhesive is applied, when a water-based adhesive or the like is used, it is preferably performed so that the thickness of the finally formed adhesive layer reaches 30 nm to 300 nm, and more preferably 60 nm to 150 nm. . On the other hand, when using an active-energy-ray-curable adhesive, it is preferable to perform so that the thickness of the said adhesive layer may become 0.2 micrometer-20 micrometers.

It should be noted that, when the polarizer and the transparent protective film are laminated, an easily-adhesive layer may be provided between the transparent protective film and the adhesive layer. The easily-adhesive layer can be formed of various resins such as a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a polysiloxane, a polyamide skeleton, a polyimide skeleton, and a polyvinyl alcohol skeleton. . These polymer resins may be used singly or in combination of two or more kinds. In addition, when forming an easily-adhesive layer, other additives may be added. Specifically, stabilizers such as a thickener, an ultraviolet absorber, an antioxidant, and a heat-resistant stabilizer can be further used.

The adhesive layer is formed of an adhesive (adhesive composition). As the adhesive, various adhesives can be used, and examples thereof include rubber-based adhesives, acrylic-based adhesives, polysiloxane-based adhesives, polyurethane-based adhesives, vinyl alkyl ether-based adhesives, and polyvinyl-based adhesives. Pyrrolidone-based adhesives, polypropylene amidamine-based adhesives, cellulose-based adhesives, and the like. The adhesive base polymer is selected according to the type of the adhesive. Among the above-mentioned adhesives, an acrylic adhesive is preferably used from the viewpoints of excellent optical transparency, exhibiting adhesive properties such as appropriate wettability, cohesiveness, and adhesiveness, and excellent weather resistance and heat resistance.

In order to improve the adhesion between the polarizer and the transparent protective film, the above-mentioned undercoat layer (primer layer) is formed. The material constituting the primer layer is not particularly limited as long as it is a material that exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability, and the like can be used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, or a mixture thereof.

<First adhesive layer> A polarizing film having a configuration in which a first adhesive layer is laminated on at least one side of the polarizing film may be used, and a surface on the opposite side of the surface of the first adhesive layer that is in contact with the polarizing film may be used. Other optical members (for example, a retardation film, a liquid crystal display device, etc.) are laminated. In addition, the first adhesive layer may be directly laminated on the undercoat layer laminated on the polarizer. An appropriate adhesive can be used in the formation of the first adhesive layer, and the type thereof is not particularly limited. Examples of the adhesive include a rubber-based adhesive, an acrylic-based adhesive, a polysiloxane-based adhesive, a polyurethane-based adhesive, a vinyl alkyl ether-based adhesive, a polyvinyl alcohol-based adhesive, and a polyethylene. Pyrrolidone-based adhesives, polypropylene amidamine-based adhesives, cellulose-based adhesives, and the like. Among these adhesives, those which are excellent in optical transparency, exhibit suitable adhesion properties such as wettability, cohesiveness, and adhesiveness, and are excellent in weather resistance, heat resistance, and the like are preferably used. As the adhesive exhibiting such characteristics, an acrylic adhesive is preferably used.

As a method for forming the first adhesive layer, for example, the following method is used to produce the adhesive: the adhesive is applied to a separator subjected to a peeling treatment, and a polymerization solvent and the like are dried and removed to form an adhesive layer, and then transferred. To a polarizing film; or a method of applying the above-mentioned adhesive to a polarizing film and drying and removing a polymerization solvent or the like to form an adhesive layer on a polarizer. In addition, when coating an adhesive agent, one or more types of solvents other than a polymerization solvent may be added suitably. As the separator subjected to the peeling treatment, a polysiloxane separator is preferably used.

In the step of applying the adhesive of the present invention to such a separator and drying to form an adhesive layer, as a method of drying the adhesive, an appropriate method may be appropriately adopted depending on the purpose. A method of heating and drying the coating film is preferably used. The heating and drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature to the above range, an adhesive having excellent adhesive properties can be obtained.

As the method for forming the first adhesive layer, various methods can be used. Specifically, for example, roll coating, roll coating, gravure coating, reverse coating, roller brush, spray coating, dip roll coating, doctor blade coating, doctor blade coating, air knife coating, curtain coating, lip mold coating, use A method such as an extrusion coating method such as a die coater.

The thickness of the first adhesive layer is preferably 2 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 35 μm.

The separator can protect the adhesive surface of the first adhesive layer until it is used for actual use. Examples of the constituent materials of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and non-woven fabrics; meshes, Suitable thin paper-like objects (thin leaf bodies) such as foamed sheets, metal foils, and laminates of these materials are preferably plastic films from the viewpoint of excellent surface smoothness. The plastic film is not particularly limited as long as it is a film capable of protecting the adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, and polymethylpentene. Olefin film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like.

If necessary, the above-mentioned separator may be subjected to a mold release and antifouling treatment using a polysiloxane, a fluorine-containing type, a long-chain alkyl group, or a fatty acid ammonium-based mold release agent or silicon dioxide powder, or may be coated. Type, kneading type, evaporation type and other antistatic treatment. In particular, the surface of the release film is appropriately subjected to a release treatment such as a polysiloxane treatment, a long-chain alkyl treatment, or a fluorine treatment, so that the releasability from the first adhesive layer can be further improved.

The thickness of the separator is usually preferably 5 μm to 50 μm, and more preferably 20 μm to 40 μm. Examples

Hereinafter, several embodiments related to the present invention will be described, but it is not intended to limit the present invention to the range shown by the specific examples. It should be noted that "parts" and "%" in the following description are quality standards unless otherwise specified. In addition, the blending amount (addition amount) in the table is shown.

In addition, each characteristic in the following description was each measured or evaluated by the following method.

<Weight average molecular weight (Mw)> The weight average molecular weight (Mw) was measured using a GPC device (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are shown below. Sample concentration: 0.2% by mass (tetrahydrofuran (THF) solution) Injection volume: 10 μl Eluent: THF Flow rate: 0.6 ml / min Measurement temperature: 40 ° C Chromatography column: Sample column: TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2) Reference column: TSKgel SuperH-RC (1) Detector: Differential refractometer (RI) It should be noted that the weight average molecular weight is obtained by polystyrene conversion.

<Glass Transition Temperature (Tg)> The glass transition temperature Tg (° C) of the polymer was determined by the following formula using the following literature value as the glass transition temperature Tgn (° C) of the homopolymer formed from each monomer. Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)] [where Tg (° C) represents the glass transition temperature of the copolymer, Wn (-) represents the mass fraction of each monomer, and Tgn (° C) represents the glass transition temperature of a homopolymer formed from each monomer, and n represents the type of each monomer. Document value: 2-ethylhexyl acrylate (2EHA): -70 ° C Butyl acrylate (BA): -55 ° C 2-hydroxyethyl acrylate (HEA): -15 ° C Acrylic acid (AA): 106 ° C

It should be noted that, as reference values, reference was made to "synthesis, design, and new application development of acrylic resins (acryl resin, synthesis, design, and new application development)" (published by the Publishing Department of the Central Management and Development Center, Japan), and "polymerization "Polymer Handbook" (John Wiley & Sons), monomer manufacturer's catalog value.

The glass transition temperature (Tg) (° C) of a (meth) acrylic polymer obtained from a monomer whose literature value is unknown can be determined by dynamic viscoelasticity measurement in the following procedure. First, a sheet of a (meth) acrylic polymer having a thickness of 20 μm was laminated to obtain a thickness of about 2 mm. The sheet was punched out to a diameter of 7.9 mm, and cylindrical particles were produced and measured as a glass transition temperature (Tg). With samples. Using the measurement sample, the measurement sample was fixed to a 7.9 mm parallel plate jig, and the temperature dependence of the loss modulus G '' was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometrics, ARES), and the obtained G The temperature at which the curve reaches its maximum is taken as the glass transition temperature (Tg) (° C). The measurement conditions are as follows. Measurement: Shear mode Temperature range: -70 ° C to 150 ° C Heating range: 5 ° C / min Frequency: 1Hz

<Storage Modulus (G ')> A 20 μm-thick adhesive layer was laminated to obtain a thickness of about 2 mm, and punched to a diameter of 7.9 mm to produce cylindrical particles for storage modulus measurement. sample. The measurement sample was fixed to a jig of 7.9 mm parallel plate, and the storage modulus (Pa) at a temperature of 23 ° C. and a frequency of 1 Hz was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometrics, ARES). In addition, the storage modulus was measured with respect to the sample using an acrylic adhesive.

<Measurement of thickness> The cross section of the surface protective film was observed with a transmission electron microscope (H-7650 manufactured by Hitachi, Ltd.), and the thickness of the adhesive layer and the like were measured.

<Initial peeling force (pickup force)> As shown in FIG. 2, the surface protection film 1 of each example was cut into a size of 50 mm in width and 100 mm in length, and the pressure-sensitive adhesive surface 20A of the surface protection film 1 was pressed at a pressure of 0.25 MPa. It was crimped at a speed of 0.3 m / min to the single-sided protective polarizing film 50 described below. A single-sided adhesive tape (manufactured by Nichiban Corporation, trade name "Cellotape (registered trademark)", width 24 mm) 60 was cut into a length of 50 mm. The adhesive surface of the adhesive tape was crimped to the center of the back surface of the surface protection film 1 with a width of 50 mm so that the end portion protruded by 30 mm with a manual roller. This was left for 10 seconds under the conditions of 23 ° C and 50% RH. Next, the maximum stress applied when peeling of the single-sided adhesive tape 60 at the time of peeling when peeling the single-sided adhesive tape 60 at a speed of 0.3 m / min in the 90 ^° direction using a universal testing machine (AUTOGRAPH) was taken as the initial peeling force (N / 50 mm).

<Production of polarizing film> (Production of polarizing film) Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75 ° C ) Corona treatment is performed on one side of the substrate, and the corona-treated surface is coated at 25 ° C with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mole%) and ethyl acetate at a ratio of 9: 1. An aqueous solution of fluorenyl-modified PVA (degree of polymerization 1200, degree of modification of acetamylacetate 4.6%, degree of saponification of 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") and dried to form A PVA-based resin layer having a thickness of 11 μm produced a laminate. The obtained laminated body was uniaxially stretched to 2.0 times in a longitudinal direction (length direction) free end between rolls having different peripheral speeds in an oven at 120 ° C (assisted stretching treatment in air). Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 30 ° C (insolubilization treatment). Next, in a dyeing bath having a liquid temperature of 30 ° C., immersion was performed while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 mass parts of iodine and 1.0 mass part of potassium iodide were mixed with 100 mass parts of water for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by mass of potassium iodide and 3 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 30 ° C (crosslinking treatment). Then, the laminate was immersed in a boric acid aqueous solution (aqueous solution obtained by mixing 4 parts by mass of boric acid and 5 parts by mass of potassium iodide with 100 parts by mass of water with 100 parts by mass of water) in the longitudinal direction between rolls having different peripheral speeds (Longitudinal direction) Uniaxial stretching is performed so that the total stretching ratio is 5.5 times (underwater stretching treatment). Then, the laminated body was immersed in a washing bath having a liquid temperature of 30 ° C. (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) (washing treatment). Thus, an optical film laminate including a polarizer having a thickness of 5 μm was obtained.

(Formation of Adhesive Layer) To a reaction vessel having a condenser tube, a nitrogen introduction tube, a thermometer, and a stirring device, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and A solution was prepared by 0.3 parts of 2,2'-azobisisobutyronitrile. Then, the solution was stirred while blowing nitrogen gas into the solution, and reacted at 55 ° C. for 8 hours to obtain a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Furthermore, ethyl acetate was added to this acrylic polymer containing solution, and the acrylic polymer solution which adjusted the solid content concentration to 30% was obtained. With respect to 100 parts of the solid content of the acrylic polymer solution, 0.5 part of a cross-linking agent containing a compound having an isocyanate group as a main component (manufactured by Japan Polyurethane Co., Ltd., with a trade name of “Coronate L”) was sequentially added as a cross-linking agent. ") And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name" KMB-403 ") as a silane coupling agent to prepare a binder solution. The above-mentioned adhesive solution was applied to the surface of a release sheet (separator) containing a polyethylene terephthalate film (thickness 38 μm) subjected to a peeling treatment so that the thickness after drying was 25 μm, and then Dry, thereby forming an adhesive layer.

(Production of single-sided protective polarizing film) A 40 μm-thick triethylammonium cellulose (TAC) film (trade name “TAC Film KC4UY” manufactured by Konica Minolta Optical) was bonded to the above via a vinyl alcohol-based adhesive The polarizer side of the optical film laminate. Next, the amorphous PET substrate was peeled, and the above-mentioned adhesive layer was bonded to the peeled surface, thereby producing a single-sided protective polarizing film.

<Preparation of acrylic polymer (1)> In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, 95 parts by mass of 2-ethylhexyl acrylate (2EHA) and 2-hydroxyethyl acrylate were charged. 5 parts by mass of ester (HEA), 0.2 parts by mass of 2,2'-azobisisobutyronitrile as polymerization initiator, and 150 parts by mass of ethyl acetate, nitrogen was introduced while slowly stirring to keep the liquid temperature in the flask A polymerization reaction was performed at about 65 ° C. for 6 hours, thereby preparing an acrylic polymer (1) solution (40% by mass). The acrylic polymer (1) had a weight average molecular weight (Mw) of 550,000 and a glass transition temperature (Tg) of -68 ° C.

<Preparation of acrylic polymer (2)> A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser was charged with 95 parts by mass of butyl acrylate (BA) and 5 parts by mass of acrylic acid (AA). As a polymerization initiator, 0.2 parts by mass of 2,2'-azobisisobutyronitrile and 234 parts by mass of ethyl acetate, nitrogen was introduced while slowly stirring, and the temperature of the liquid in the flask was maintained at about 63 ° C. for 7 hours. A polymerization reaction was performed to prepare an acrylic polymer (2) solution (30% by mass). The acrylic polymer (2) had a weight average molecular weight (Mw) of 600,000 and a glass transition temperature (Tg) of -50 ° C.

[Preparation of Acrylic Adhesive 1 Solution] The above-mentioned acrylic polymer (1) solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass of the solution (100 parts by mass of solid content) was added. Trimethylolpropane / toluene diisocyanate terpolymer adduct (manufactured by Tosoh Corporation, Coronate L: C / L) as a cross-functional isocyanate compound as a crosslinking agent 2.7 parts by mass (2 parts by mass of solid content) 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (solid content: 0.03 parts by mass) as a crosslinking catalyst, and the mixture was stirred to prepare an acrylic adhesive 1 solution.

[Preparation of Acrylic Adhesive 2 Solution] The above-mentioned acrylic polymer (1) solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass of the solution (100% by mass of solid content) was added. 4 parts by mass (4 parts by mass of solid content) of an isocyanurate form of hexamethylene diisocyanate (manufactured by Tosoh Corporation, Coronate HX: C / HX) as a cross-functional isocyanate compound as a crosslinking agent, as 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (solid content: 0.03 parts by mass) of the cross-linking catalyst was mixed and stirred to prepare an acrylic adhesive 2 solution.

[Preparation of Acrylic Adhesive 3 Solution] The above-mentioned acrylic polymer (2) solution (30% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass (100% by mass of solid content) of the solution was added. 5 parts by mass (5 parts by mass of solid content) of an epoxy compound (manufactured by Mitsubishi Gas Chemical Co., Ltd., TETRAD-C: T / C) was used as a cross-linking agent, followed by mixing and stirring to prepare an acrylic adhesive 3 solution.

<Example 1> [Production of surface protection film] The solution of the above-mentioned acrylic adhesive 1 was applied to one side of a polyester film (manufactured by Toyobo Co., Ltd., E5000) having a thickness of 38 μm, and heated at 130 ° C. for 2 minutes to form a thickness of 1 μm. Adhesive layer. Next, a polysiloxane treatment surface of a polyethylene terephthalate film (thickness: 25 μm) which had been treated with polysiloxane on one side was bonded to the surface of the adhesive layer to prepare a surface protection. film.

<Example 2> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 1 except that the above-mentioned acrylic adhesive solution 2 was used.

<Example 3> [Production of a surface protection film] Using the acrylic adhesive solution 2 described above, a 50 μm thick polyester film (manufactured by Toyobo Co., Ltd., E5000) as a base film was coated on one side to form a 1.9 μm thick adhesive. A surface protective film was produced in the same manner as in Example 2 except for the agent layer.

<Example 4> [Production of a surface protection film] The acrylic adhesive solution 3 was applied to one side of a polyester film (manufactured by Toyobo Co., Ltd., E5000) having a thickness of 38 μm, and heated at 130 ° C for 2 minutes to form a thickness of 0.5. μm adhesive layer. Next, a polysiloxane treatment surface of a polyethylene terephthalate film (thickness: 25 μm) which had been treated with polysiloxane on one side was bonded to the surface of the adhesive layer to prepare a surface protection. film.

<Examples 5 to 9> In the same manner as in Example 4, a solution of acrylic adhesive 3 was used to form a polyester film (manufactured by Toyobo Co., Ltd., E5100: 38 μm, 50 μm, 50 μm, 50 μm, A substrate film of 75 μm, a substrate film of E5101: a substrate film of 25 μm) was coated on one side to form an adhesive layer of each thickness (0.5 μm, 1 μm, 1.9 μm) shown in Table 3 to prepare a surface protective film.

<Example 10> [Preparation of Polyurethane Adhesive 4 Solution] 85 parts by mass of PREMINOL S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) as a polyol having 3 hydroxyl groups was blended as a polyol, and 3 hydroxyl groups were used as the polyol. 13 parts by mass of polyhydric alcohol SANNIX GP3000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 3000), 2 parts by mass of SANNIX GP1000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 1000) as a crosslinking agent 18 parts by mass of an isocyanate compound (Coronate HX: C / HX, manufactured by Tosoh Corporation), 0.04 parts by mass of acetoacetone iron (III) (manufactured by Tokyo Chemical Industry Co., Ltd.) as a catalyst, and 210 parts by mass of ethyl acetate as a diluting solvent Parts to obtain a solution of a polyurethane-based adhesive 4.

[Production of Surface Protection Film] A surface protection film was produced by the same method and conditions as in Example 1 except that the solution of the polyurethane-based adhesive 4 was used.

<Example 11> [Preparation of 5 solution of polysiloxane-based adhesive] "X-40-3229" (solid content: 60% by mass) was added as a polysiloxane-based adhesive based on 100 parts by mass of solid content. , Manufactured by Shin-Etsu Chemical Industry Co., Ltd.), 0.5 parts by mass of "CAT-PL-50T" (manufactured by Shin-Etsu Chemical Industry Co., Ltd.) as a platinum catalyst, and 100 parts by mass of toluene as a solvent to obtain a polysiloxane-based adhesive 5 Solution.

[Production of Surface Protection Film] A surface protection film was produced by the same method and conditions as in Example 1 except that the solution of the polysiloxane-based adhesive 5 was used.

<Example 12> [Preparation of Acrylic Adhesive 6 Solution] The above-mentioned acrylic polymer (1) solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass of the solution (solid content 100) Part by mass) was added 25R-1 (manufactured by Idecco, polyethylene oxide-polypropylene oxide block polymer, trade name "Adeka Pluronic 25R-1") as a compound containing an alkylene oxide (AO) group. ) 0.5 part by mass (0.5 part by mass of solid content) as a cross-linking agent and as a trifunctional isocyanate compound as a hexamethylene diisocyanate isocyanurate form (manufactured by Tosoh Corporation, Coronate HX: C / HX) 4 parts by mass (4 parts by mass of solid content), 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (0.03 parts by mass of solid content) as a crosslinking catalyst, and mixed and stirred to prepare acrylic Binder 6 solution.

[Production of Surface Protection Film] A surface protection film was produced in the same manner as in Example 1 except that the above-mentioned acrylic adhesive 6 solution was used.

<Example 13> [Preparation of Acrylic Adhesive 7 Solution] The above-mentioned acrylic polymer (1) solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass of the solution (solid content 100) Parts by mass) HS-10 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate, trade name "Aqualon HS-10" is added as a compound containing an alkylene oxide (AO) group. ") 3.0 parts by mass (3.0 parts by mass of solid content) as a cross-linking agent and as a trifunctional isocyanate compound as a hexamethylene diisocyanate in an isocyanurate form (manufactured by Tosoh Corporation, Coronate HX: C / HX ) 4 parts by mass (4 parts by mass of solid content), 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (0.03 parts by mass of solid content) as a crosslinking catalyst, and mixed and stirred to prepare acrylic acid Binder-like 7 solution.

[Production of Surface Protection Film] A surface protection film was produced in the same manner as in Example 1 except that the acrylic adhesive 7 solution was used.

<Comparative example 1> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 1 except that the thickness of the adhesive layer was 5 μm.

<Comparative example 2> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 2 except that the thickness of the adhesive layer was 5 μm.

<Comparative example 3> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 5 except that the thickness of the adhesive layer was 2 μm.

<Comparative example 4> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 5 except that the thickness of the adhesive layer was 5 μm.

<Comparative example 5> [Production of surface protection film] A surface protection film was produced in the same manner as in Example 6 except that the thickness of the adhesive layer was 5 μm.

The surface protection films of Examples and Comparative Examples are shown in Tables 1 to 3 and the results of the above blending contents and various measurements and evaluations.

Table 1

Table 2

table 3

From Table 3, it was confirmed that, in all the examples, since the surface protective film having a thickness of less than 2 μm of the adhesive layer was used, the initial peeling force can be suppressed to be low. On the other hand, it was confirmed that in all the comparative examples, since the thickness of the adhesive layer was 2 μm or more, the initial peeling force was improved. Industrial applicability

The surface protection film disclosed herein is suitable for protection as a thin optical member used as a constituent element of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, etc. during manufacture, transportation, etc. The surface protection film of this optical member. In particular, it is used as a surface protection film for optical components such as polarizing films, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light diffusion films, and reflection films for liquid crystal display panels (surface protection films for optics) is useful.

1‧‧‧ surface protection film

2, 50‧‧‧ polarizing film

12‧‧‧ substrate film

20‧‧‧Adhesive layer

20A‧‧‧Adhesive surface

21‧‧‧first adhesive layer

22, 23‧‧‧ Adhesive layer

30, 31‧‧‧ transparent protective film

40‧‧‧Polarizer

60‧‧‧Single-sided adhesive tape

62‧‧‧Adhesive layer (adhesive surface)

64‧‧‧ substrate

FIG. 1 is a schematic cross-sectional view illustrating a configuration example in which the surface protection film of the present invention is adhered to a polarizing film. FIG. 2 is an explanatory diagram showing a method for measuring an initial peeling force.

Claims (6)

A surface protection film is composed of a substrate film and an adhesive layer. The adhesive layer is formed on at least one side of the substrate film. The surface protection film is characterized in that the thickness of the adhesive layer is less than 2 μm. For example, the surface protection film of claim 1, wherein the 90 ^° peeling initial peeling force of the aforementioned surface protection film on the triethyl cellulose film at 23 ° C and 50% RH is 1N / 50mm or less. The surface protection film according to claim 1 or 2, wherein the thickness of the substrate film is 20 μm or more. The surface protection film according to any one of claims 1 to 3, wherein the adhesive layer contains at least one selected from the group consisting of an acrylic adhesive, a polyurethane adhesive, and a polysiloxane adhesive. . An optical member characterized by being protected by a surface protective film according to any one of claims 1 to 4. The optical member according to claim 5, wherein the optical member is a polarizing film including a polarizer, and the thickness of the polarizer is 8 μm or less.