JP6867788B2 - Surface protective film and optical members - Google Patents

Description

The present invention relates to a surface protective film and an optical member protected by the surface protective film.

The surface protective film generally has a structure in which an adhesive layer is provided on a film-like base material (support). Such a protective film is attached to an adherend (protected body) via the pressure-sensitive adhesive layer, and is used for the purpose of protecting the adherend from scratches and stains during processing and transportation.

For example, a touch panel of a liquid crystal display is formed by bonding optical members such as a polarizing plate and a wave plate to a liquid crystal cell via an adhesive layer. In the manufacture of such a liquid crystal display panel, the polarizing plate to be bonded to the liquid crystal cell is once manufactured in a roll form, then unwound from the roll and cut into a desired size according to the shape of the liquid crystal cell for use. .. Here, in order to prevent the polarizing plate from being scratched by rubbing against the transport roll or the like in the intermediate process, measures are taken to attach a surface protective film to one side or both sides (typically one side) of the polarizing plate.

Generally, since the surface protective film and the optical member are made of a plastic material, they have high electrical insulation and generate static electricity due to friction or peeling. Therefore, static electricity is likely to be generated even when the surface protective film is peeled off from an optical member such as a polarizing plate, and if a voltage is applied to the liquid crystal with the static electricity remaining, the orientation of the liquid crystal molecules may be lost or the orientation of the liquid crystal molecules may be lost. In addition, there is a concern that the panel may be damaged. In addition, the presence of static electricity can be a factor of sucking dust and reducing workability. For this reason, antistatic treatment is applied to the surface protective film. For example, as the surface layer (top coat layer, back layer) of the surface protective film, an antistatic layer is formed or an antistatic coating is applied. (See Patent Documents 1 and 2).

Further, in order to impart an antistatic function to the surface protective film, an antistatic component such as an ionic compound is used as a raw material of the pressure-sensitive adhesive layer used (Patent Document 3). Here, the surface protective film imparts antistatic properties to the adherend by attaching an adhesive layer to the adherend and transferring a small amount of an antistatic component to the surface of the adherend. When a polarizing plate with reduced reflectance, which is used to suppress surface reflection of an image display device, is used as an adherend, the surface of the polarizing plate is contaminated by the transfer of an antistatic component to the surface of the polarizing plate, and the polarizing plate is plated. The reflectance of the light is changed, which causes a problem that it cannot be used for an image display device.

On the other hand, by forming an antistatic undercoat layer (antistatic layer) between the base material constituting the surface protective film and the pressure-sensitive adhesive layer to make the pressure-sensitive adhesive layer low in contamination. A method of suppressing the generation of static electricity when the surface protective film is peeled off from an optical member such as a polarizing plate is adopted (Patent Document 4). However, the conventional low-staining pressure-sensitive adhesive layer has not obtained sufficient anchoring property with respect to the undercoat layer, and problems such as peeling occur at the interface between the pressure-sensitive adhesive layer and the undercoat layer. ing.

Japanese Unexamined Patent Publication No. 2004-223923 Japanese Unexamined Patent Publication No. 2008-255332 Japanese Unexamined Patent Publication No. 2013-185007 Japanese Unexamined Patent Publication No. 2001-316443

Therefore, as a result of diligent research in view of the above circumstances, the present invention includes a surface protective film having excellent anchoring properties for the antistatic layer of the adhesive layer, peeling antistatic properties, and stain resistance. , It is an object of the present invention to provide an optical member protected by the surface protective film.

That is, the surface protective film of the present invention has an antistatic layer on at least one surface of the base material, and contains a (meth) acrylic polymer on the side of the antistatic layer opposite to the surface in contact with the base material. A surface protective film having an adhesive layer formed of an adhesive composition, wherein the antistatic layer contains a water-soluble conductive polymer and / or a water-dispersible conductive polymer, and a polyester resin as a binder. The surface resistance value of the antistatic layer formed from the inhibitor composition is 1.0 × 10 ¹⁰ Ω / □ or less, and the molecular weight distribution (Mw / Mn) of the (meth) acrylic polymer is 6 or less. It is characterized by being.

In the surface protective film of the present invention, it is preferable that the base material is a polyester film.

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

The surface protective film of the present invention has an antistatic layer between a base material and an adhesive layer, and the antistatic layer contains a specific conductive polymer component and a specific binder. Since it is formed from, it is difficult to form a fragile layer on the surface of the antistatic layer, a uniform antistatic layer can be formed, workability is excellent, and peeling antistatic property based on the antistatic layer is good. By forming the pressure-sensitive adhesive layer from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer having a specific molecular weight distribution, the low-molecular-weight components contained in the pressure-sensitive agent layer can be suppressed to a small extent, and the pressure-sensitive agent layer can be suppressed. It is possible to obtain a surface protective film that does not easily form a fragile layer on the surface, has excellent anchoring property for the antistatic layer of the adhesive layer, and also has excellent stain resistance, and an optical member protected by the surface protective film. , Useful.

It is a schematic cross-sectional view which shows one structural example of the surface protection film which concerns on this invention. It is explanatory drawing which shows the measuring method of the peeling band voltage.

Hereinafter, embodiments of the present invention will be described in detail.

<Overall structure of surface protective film>
The surface protective film disclosed herein is generally in the form of an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film, a surface protective sheet, or the like, and is particularly on a touch sensor or glass in a liquid crystal display panel. It is suitable as a surface protective film that protects the surface of the optical member during processing or transportation of an optical member such as a polarizing plate attached to the label via an adhesive layer. The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form, and is formed in a regular or random pattern such as a dot shape or a striped shape. It may be an adhesive layer. Further, the surface protective film disclosed herein may be in the form of a roll or in the form of a single leaf.

A typical configuration example of the surface protective film disclosed herein is schematically shown in FIG. The surface protective film 1 is provided on a base material (for example, a polyester film) 11, an antistatic layer 12 provided on one side thereof, and one side of the antistatic layer 12 (the surface opposite to the base material 11). The pressure-sensitive adhesive layer 13 is provided. The surface protective film 1 has an adhesive layer 13 as an adherend (as a protection target, an optical plate such as a polarizing plate attached to a touch sensor in a liquid crystal display panel (touch panel) or a base glass via the adhesive layer 13). It is used by pasting it on the surface of the member. The surface protective film 1 before use (that is, before sticking to the adherend) has a separator in which the surface of the pressure-sensitive adhesive layer 13 (the surface to be stuck to the adherend) is at least the adhesive layer 13 side as a peeling surface. It may be in a form protected by (peeling liner) 14. Alternatively, the surface protective film 1 is wound in a roll shape so that the pressure-sensitive adhesive layer 13 comes into contact with the back surface of the base material 11 (the surface opposite to the antistatic layer 12) to protect the surface. It may be.

<Base material>
The surface protective film of the present invention has a base material, has an antistatic layer on at least one surface of the base material, and has (meth) acrylic on the side of the antistatic layer opposite to the surface in contact with the base material. It is characterized by having a pressure-sensitive adhesive layer formed by a pressure-sensitive adhesive composition containing a based polymer. In the technique disclosed herein, the resin material constituting the base material can be used without particular limitation, and for example, transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, and flexibility. It is preferable to use one having excellent properties such as properties and dimensional stability. In particular, since the base material has flexibility, the pressure-sensitive 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 base material (support), for example, polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate-based polymers; poly A plastic film composed of a resin material containing an acrylic polymer such as methyl methacrylate; or the like as a main resin component (a main component among the resin components, typically a component accounting for 50% by mass or more) is used as the base material. It can be preferably used. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; olefin-based polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Examples thereof include those using a vinyl chloride polymer; an amide polymer such as nylon 6, nylon 6, 6, and aromatic polyamide; and the like as a resin material. Still other examples of the resin material include imide-based polymers, sulfone-based polymers, polyether sulfone-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, and vinyl butyral-based polymers. , Arilate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer and the like. It may be a base material composed of a blend of two or more of the above-mentioned polymers.

As the base material, a plastic film made of a transparent thermoplastic resin material can be preferably adopted. Among the plastic films, it is more preferable to use a polyester film. Here, the polyester film is mainly composed of a polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate. Say. Such a polyester film has preferable properties as a base material of a surface protective film, such as excellent optical properties and dimensional stability. Above all, it is particularly preferable to contain polyethylene terephthalate and / or polyethylene naphthalate as the base material.

If necessary, the resin material constituting the base material may contain various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.). On one side of the polyester film (the surface on the side where the antistatic layer is provided), for example, a known or conventional surface such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of an undercoat agent, etc. It may be treated. Such a surface treatment may be, for example, a treatment for enhancing the adhesion between the base material and the antistatic layer. A surface treatment in which a polar group such as a hydroxyl group is introduced into the surface of the base material can be preferably adopted.

The surface protective film of the present invention has an antistatic function by having an antistatic layer on the base material, but it is also possible to use a plastic film which has been subjected to antistatic treatment as the base material. is there. It is preferable to use the base material because the charge of the surface protective film itself at the time of peeling can be suppressed. Further, the base material is a plastic film, and by applying the antistatic treatment to the plastic film, the surface protective film itself can be reduced in charge and the adherend has an excellent antistatic ability. The method for imparting the antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin, a conductive polymer, or a conductive substance composed of an antistatic agent and a resin component can be used. Examples thereof include a method of applying the contained conductive resin, a method of depositing or plating a conductive substance, and a method of kneading an antistatic agent or the like.

The thickness of the base material is usually about 5 to 200 μm, preferably about 10 to 100 μm. When the thickness of the base material is within the above range, it is preferable because it is excellent in the workability of attaching to the adherend and the workability of peeling from the adherend.

<Antistatic layer>
The surface protective film of the present invention has an antistatic layer on at least one surface of a base material, and a pressure-sensitive adhesive containing a (meth) acrylic polymer on the side of the antistatic layer opposite to the surface in contact with the base material. A surface protective film having an adhesive layer formed by the composition, wherein the antistatic layer contains a water-soluble conductive polymer and / or a water-dispersible conductive polymer, and a polyester resin as a binder. It is made of an object and has a surface resistance value of 1.0 × 10 ¹⁰ Ω / □ or less. Since the surface protective film has an antistatic layer between the base material and the pressure-sensitive adhesive layer, the surface protective film has antistatic properties for peeling and stain resistance (low) when peeled after being attached to an adherend. It is excellent in contaminating property) and is a preferable embodiment.

<Conductive polymer>
The antistatic layer is characterized by being formed from an antistatic agent composition containing a water-soluble conductive polymer and / or a water-dispersible conductive polymer as a conductive polymer component. By using the conductive polymer, the peeling antistatic property based on the antistatic layer can be satisfied. Further, although the conductive polymer is "water-soluble" or "water-dispersible", it is immobilized in the antistatic layer by using a cross-linking agent (for example, a melamine-based or isocyanate-based cross-linking agent) described later. It can improve water resistance. By using the water-soluble conductive polymer and / or the water-dispersible conductive polymer, the surface resistance value of the antistatic layer can be suppressed low, and further, it can contribute to the peeling antistatic property of the surface protective film, which is preferable. It becomes an aspect.

The amount of the conductive polymer used is preferably 10 to 200 parts by mass, more preferably 25 to 150 parts by mass, and further preferably 40 to 120 parts by mass with respect to 100 parts by mass of the binder contained in the antistatic layer. It is a mass part. If the amount of the conductive polymer used is too small, the antistatic effect may be small, and if the amount of the conductive polymer used is too large, the adhesion of the antistatic layer to the substrate may be reduced or the transparency may be reduced. It is not preferable because it may decrease.

As a method for forming the antistatic layer, a method of applying and drying (or curing) a coating material (antistatic agent composition) for forming an antistatic layer on the first surface of a base material (support) can be adopted. As the conductive polymer component used for preparing the coating material, a water-soluble conductive polymer and / or a water-dispersible conductive polymer and a polyester resin as a binder are contained as essential components, and the conductive polymer is contained in water. A dissolved / dispersed form (a conductive polymer aqueous solution or a conductive polymer dispersion) can be preferably used. Such a conductive polymer aqueous solution or an aqueous dispersion is prepared by dissolving, for example, a conductive polymer having a hydrophilic functional group (which can be synthesized by a method such as copolymerizing a monomer having a hydrophilic functional group in the molecule) in water. -Can be prepared by dispersing. The hydrophilic functional group, a sulfo group, an amino group, an amide group, an imino group, a hydroxyl group, a mercapto group, a hydrazino group, a carboxyl group, quaternary ammonium groups, sulfate ester group (-O-SO 3 _H), phosphorus An acid ester group (for example, -O-PO (OH) ₂ ) and the like are exemplified. Such hydrophilic functional groups may form salts.

The water-soluble conductive polymer can be used without particular limitation, and examples thereof include polyaniline sulfonic acid, poly (isothianaftendiyl-sulfonate) compounds, and quaternary ammonium salt-containing (meth) acrylic acid ester-based polymers. The water-dispersible conductive polymer can be used without particular limitation, and examples thereof include polythiophenes and polyanilines doped with polyanions. Among them, polyaniline sulfonic acid is preferably used as the water-soluble conductive polymer, and polythiophenes doped with polyanions are preferably used as the water-dispersible conductive polymer.

Examples of polythiophenes that can be used as the water-dispersible conductive polymer include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), and poly (3-butylthiophene). , Poly (3-hexylthiophene), Poly (3-heptylthiophene), Poly (3-octylthiophene), Poly (3-decylthiophene), Poly (3-dodecylthiophene), Poly (3-octylthiophene), Poly (3-Bromothiophene), poly (3-chlorothiophene), poly (3-iodothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), poly (3-hydroxythiophene), poly (3-methoxythiophene), poly (3-ethoxythiophene), poly (3-butoxythiophene), poly (3-hexyloxythiophene), Poly (3-heptyloxythiophene), poly (3-octyloxythiophene), poly (3-decyloxythiophene), poly (3-dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3,4) -Dihydroxythiophene), poly (3,4-dimethoxythiophene), poly (3,4-diethoxythiophene), poly (3,4-dipropoxythiophene), poly (3,4-dibutoxythiophene), poly (3,4-dibutoxythiophene) 3,4-dihexyloxythiophene), poly (3,4-diheptyloxythiophene), poly (3,4-dioctyloxythiophene), poly (3,4-didecyloxythiophene), poly (3,4-dihexyloxythiophene), poly (3,4-dihexyloxythiophene) Didodecyloxythiophene), poly (3,4-ethylenedioxythiophene), poly (3,4-propylene dioxythiophene), poly (3,4-butendioxythiophene), poly (3-methyl-4- (Methoxythiophene), poly (3-methyl-4-ethoxythiophene), poly (3-carboxythiophene, poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxyethylthiophene), poly ( 3-Methyl-4-carboxybutylthiophene) may be mentioned. These may be used alone or in combination of two or more. Among them, poly (3,4-) from the viewpoint of conductivity. Ethylenedioxythiophene) (PEDOT) is preferred.

The polythiophenes have a degree of polymerization of preferably 2 to 1000, more preferably 5 to 100. When it is within the above range, it is preferable because it is excellent in conductivity.

The polyanions are polymers of structural units having an anion groups and serve as dopants for polythiophenes. Examples of the polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly (2-acrylamide-2-methylpropanesulfonic acid), and polyisoprene sulfonic acid. Polysulfoethyl methacrylate, poly (4-sulfobutylmethacrylate), polymetallicyloxybenzenesulfonic acid, polyvinylcarboxylic acid, polystyrenecarboxylic acid, polyallylcarboxylic acid, polyacryliccarboxylic acid, polymethacrylcarboxylic acid, poly (2-acrylamide) -2-Methylpropanecarboxylic acid), polyisoprenecarboxylic acid, polyacrylic acid, polysulfonated phenylacetylene and the like. These homopolymers may be used, or two or more kinds of copolymers may be used. Of these, polystyrene sulfonic acid (PSS) is preferable from the viewpoint of improving the conductivity and dispersibility of polythiophenes.

The polyanions have a weight average molecular weight (Mw) of preferably 10 to 1,000,000, more preferably 2000 to 500,000. When it is within the above range, it is preferable because it is excellent in doping and dispersibility to polythiophenes.

As the antistatic layer, for example, poly (3,4-ethylenedioxythiophene) (PEDOT) is used as the polythiophenes, and polystyrene sulfonic acid (PSS) is used as the polyanions capable of doping the polypolythiophenes. In such a case, PEDOT and PSS interact with each other and exist at a close distance, so that the electrons of PEDOT are taken away by PSS and the antistatic layer can exhibit conductivity, which is a preferable embodiment.

Examples of commercially available products of polythiophenes doped with the polyanions include poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (PEDOT / PSS), trade name "Bytron P" manufactured by BAYER, Shin-Etsu. Examples thereof include the product name "Sepruzida" manufactured by Polymer Co., Ltd. and the product name "Verazole" manufactured by Soken Kagaku Co., Ltd.

Polyaniline sulfonic acids which may be used as the water-soluble electroconductive polymer component has a weight average molecular weight (Mw) in terms of polystyrene is preferably not more 5 × 10 ⁵ or less, more preferably 3 × 10 ⁵ or less. The weight average molecular weight of these conductive polymers is usually preferably 1 × 10 ³ or more, and more preferably 5 × 10 ³ or more.

Examples of commercially available products of the polyaniline sulfonic acid include the trade name "aquaPASS" manufactured by Mitsubishi Rayon Co., Ltd.

The antistatic layer disclosed herein includes, for example, one or more other antistatic components (organic conductive substance other than the conductive polymer, inorganic conductive substance, antistatic) in addition to the conductive polymer component. Agents, etc.) may be included together. In a preferred embodiment, the antistatic layer does not substantially contain an antistatic component other than the conductive polymer, that is, the antistatic component contained in the antistatic layer substantially contains the conductive polymer. A mode consisting of only can be more preferably practiced.

Examples of the organic conductive substance include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary amino groups, secondary amino groups, and tertiary amino groups; sulfonates and sulfate esters. Anionic antistatic agents having anionic functional groups such as salts, phosphonates and phosphate ester salts; amphoteric ionic antistatic agents such as alkylbetaine and its derivatives, imidazoline and its derivatives, alanine and its derivatives; aminoalcohol And nonionic antistatic agents such as glycerin and its derivatives, polyethylene glycol and its derivatives; polymerize monomers having the cationic, anionic and amphoteric ionic conductive groups (eg, quaternary ammonium bases). Alternatively, an ionic conductive polymer obtained by copolymerization; a conductive polymer such as polythiophene, polyaniline, polypyrrole, polyethyleneimine, an allylamine-based polymer; can be mentioned. One type of such antistatic agent may be used alone, or two or more types may be used in combination.

Examples of the inorganic conductive substance include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, and cobalt. Examples thereof include copper iodide, ITO (indium oxide / tin oxide), and ATO (antimony oxide / tin oxide). Such an inorganic conductive substance may be used alone or in combination of two or more.

Examples of the antistatic agent include a cationic antistatic agent, an anionic antistatic agent, a zwitterionic antistatic agent, a nonionic antistatic agent, and a monomer having a cationic, anionic, and zwitterionic ionic conductive group. An ionic conductive polymer obtained by polymerizing or copolymerizing the above, and the like can be mentioned.

<Binder>
The antistatic layer is characterized by containing a polyester resin as a binder as an essential component. The polyester resin is preferably a resin material containing polyester as a main component (typically, a component that exceeds 50% by mass, preferably 75% by mass or more, for example, 90% by mass or more). The polyester is typically a polyvalent carboxylic acid having two or more carboxyl groups in one molecule (typically a dicarboxylic acid) and a derivative thereof (anhydride, esterified product, halogen of the polyvalent carboxylic acid). Select from one or more compounds (polycarboxylic acid component) selected from compounds (such as compounds) and polyhydric alcohols (typically diols) having two or more hydroxyl groups in one molecule. It is preferable to have a structure in which one kind or two or more kinds of compounds (polyhydric alcohol components) are condensed.

Examples of compounds that can be adopted as the polyvalent carboxylic acid component include oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±) -apple acid, and meso. -Tartrate acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipic acid, dimethyl Adipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactalic acid, pimelic acid, suberic acid, perfluorosveric acid, 3,3,6,6-tetramethylsveric acid, azelaic acid, sebacic acid, perfluoro Aliphatic dicarboxylic acids such as sebacic acid, brassic acid, dodecyldicarboxylic acid, tridecyldicarboxylic acid, tetradecyldicarboxylic acid; cycloalkyldicarboxylic acid (eg, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid), Alicyclic dicarboxylic acids such as 1,4- (2-norbornene) dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid (hymic acid), adamantandicarboxylic acid, spiroheptandicarboxylic acid; phthalic acid, isophthalic acid, dithio Isophthalic acid, methylisophthalic acid, dimethylisophthalic acid, chloroisophthalic acid, dichloroisophthalic acid, terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, oxofluorangecarboxylic acid, anthracendicarboxylic acid , Biphenyldicarboxylic acid, biphenylenedicarboxylic acid, dimethylbiphenylenedicarboxylic acid, 4,4 "-p-terephenylenedicarboxylic acid, 4,4" -p-quarelphenyldicarboxylic acid, bibenzyldicarboxylic acid, azobenzenedicarboxylic acid, homophthalic acid , Phenylene diacetic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3,3'-[4,4'-(methylenedi-p-biphenylene) dipropionic acid, Aromatic dicarboxylic acids such as 4,4'-bibenzyldiacetic acid, 3,3'(4,4'-bibenzyl) dipropionic acid, oxydi-p-phenylene diacetic acid; the acid of any of the polyvalent carboxylic acids described above. Anhydrous; the es of any of the polyvalent carboxylic acids mentioned above Tel (eg alkyl ester). It can be a monoester, a diester, or the like. ); An acid halide corresponding to any of the above-mentioned polyvalent carboxylic acids (for example, dicarboxylic acid chloride); and the like.

Preferable examples of the compound that can be adopted as the polyvalent carboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid and their acid anhydrides; adipic acid, sebacic acid, azelaic acid, and succinic acid. With aliphatic dicarboxylic acids such as fumaric acid, maleic acid, hymic acid, 1,4-cyclohexanedicarboxylic acid and acid anhydrides thereof; and lower alkyl esters of the dicarboxylic acids (for example, monoalcohol having 1 to 3 carbon atoms). Esther) and the like.

On the other hand, examples of compounds that can be adopted as the polyhydric alcohol component include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,4-butanediol. , Neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, diethylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl- Diols such as 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, xylylene glycol, hydrogenated bisphenol A, and bisphenol A. Can be mentioned. Other examples include alkylene oxide adducts of these compounds (eg, ethylene oxide adducts, propylene oxide adducts, etc.).

The molecular weight of the polyester resin has a weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) as (Mw), e.g. 5 × ¹⁰ 3 ~1.5 × ¹⁰ about ⁵ (preferably 1 × 10 It can be about ^{4 to} 6 × 10 ^4). The glass transition temperature (Tg) of the polyester resin can be, for example, 0 to 120 ° C (preferably 10 to 80 ° C).

As the polyester resin, a commercially available trade name "Byronal" manufactured by Toyobo Co., Ltd. can be used.

The antistatic layer is a resin other than the polyester resin (for example, acrylic resin, acrylic retan resin) as a binder as long as the performance of the surface protective film disclosed herein (for example, performance such as antistatic property) is not significantly impaired. , Acrylic styrene resin, acrylic silicone resin, silicone resin, polysilazane resin, polyurethane resin, fluororesin, polyvinyl alcohol resin, polyolefin resin and the like, one or more resins) may be further contained. The reason for using polyester resin as a binder is that the surface free energy is smaller than that of resins other than polyester resin (for example, the acrylic resin, polyvinyl alcohol resin, etc.), so additives such as lubricants are added. Even if this is not done, repelling and the like can be suppressed when the antistatic agent composition is applied to the base material to form a film. Further, a preferred embodiment of the technique disclosed herein is a case where the binder of the antistatic layer is substantially made of polyester resin only. For example, an antistatic layer in which the ratio of the polyester resin to the binder is 98 to 100% by mass is preferable. The ratio of the binder to the entire antistatic layer can be, for example, 50 to 95% by mass, and usually 60 to 90% by mass is appropriate.

<Crosslinking agent>
As the antistatic layer, a melamine-based, isocyanate-based, epoxy-based, or other cross-linking agent used for cross-linking a general resin can be appropriately selected and used as the cross-linking agent. As a preferred embodiment, at least a melamine-based cross-linking agent or an isocyanate-based cross-linking agent is used among the cross-linking agents. By using the cross-linking agent, a water-soluble conductive polymer or a water-dispersible conductive polymer, which are essential components when forming an antistatic layer, can be immobilized in the antistatic layer, and has water resistance and solvent resistance. An excellent effect of improvement can be realized.

Further, as the isocyanate-based cross-linking agent, it is preferable to use a blocked isocyanate-based cross-linking agent that is stable even in an aqueous solution. As a specific example of the blocked isocyanate-based cross-linking agent, an isocyanate-based cross-linking agent that can be used in the preparation of a general pressure-sensitive adhesive layer or antistatic layer (for example, an isocyanate compound (isocyanate) used in the pressure-sensitive adhesive layer described later). Alcohols, phenols, thiophenols, amines, imides, oximes, lactams, active methylene compounds, mercaptans, imines, ureas, diaryl compounds, and isocyanates. You can use the one blocked with soda.

Usually, the antistatic agent composition used for forming the antistatic layer contains a surfactant, a leveling agent, a lubricant, and the like, thereby suppressing the occurrence of cissing and uneven thickness at the time of application. However, by including these additives, a fragile layer is formed in the antistatic layer, and peeling or the like occurs at the interface where the antistatic layer and the adhesive layer come into contact with each other. It is preferable not to mix. If necessary, other antistatic components may be added in addition to the above conductive polymer, and antioxidants, colorants (pigments, dyes, etc.), fluidity modifiers (thixotropic agents, thickeners, etc.) may be added. ), Film-forming aids, surfactants (antifoaming agents, etc.), preservatives and other additives.

<Formation of antistatic layer>
The antistatic layer is a liquid composition (coating material for forming an antistatic layer, antistatic) in which essential components such as the conductive polymer component and additives used as necessary are dissolved in an appropriate solvent (water, etc.). It can be suitably formed by a method involving the application of an inhibitor composition) to a substrate. For example, a method of applying the coating material to one side of the base material, drying it, and performing a curing treatment (heat treatment, ultraviolet treatment, etc.) as necessary can be preferably adopted. The NV (nonvolatile content) of the coating material can be, for example, 5% by mass or less (typically 0.05 to 5% by mass), and usually 1% by mass or less (typically 0.10 to 0% by mass). 1% by mass) is appropriate. When forming an antistatic layer having a small thickness, it is preferable that the NV of the coating material is, for example, 0.05 to 0.50% by mass (for example, 0.10 to 0.40% by mass). By using the low NV coating material in this way, a more uniform antistatic layer can be formed.

As the solvent constituting the coating material for forming the antistatic layer, a solvent capable of stably dissolving (dispersing) the forming component of the antistatic layer is preferable. Such a solvent can be an organic solvent, water, or a mixed solvent thereof. Examples of the organic solvent include esters such as ethyl acetate; ketones such as methyl ethyl ketone, acetone and cyclohexanone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic ethers such as n-hexane and cyclohexane. Hydrocarbons; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol and cyclohexanol; alkylene glycol monoalkyl ethers (eg, ethylene glycol monomethyl ethers) , Ethylene glycol monoethyl ether), glycol ethers such as dialkylene glycol monoalkyl ether; etc .; one or more selected from the above can be used. In a preferred embodiment, the solvent of the coating material is water or a mixed solvent containing water as a main component (for example, a mixed solvent of water and ethanol).

<Characteristics of antistatic layer>
The thickness of the antistatic layer in the techniques disclosed herein is typically 3 to 500 nm, preferably 3 to 100 nm, and more preferably 3 to 60 nm. If the thickness of the antistatic layer is too small, it becomes difficult to form the antistatic layer uniformly (for example, the thickness of the antistatic layer varies greatly depending on the location), and therefore, the appearance of the surface protective film. May be prone to unevenness. On the other hand, if it is too thick, it may affect the characteristics of the base material (optical characteristics, dimensional stability, etc.).

The surface protective film disclosed herein has a surface resistance value (Ω / □) measured on the surface of the antistatic layer of 1.0 × 10 ¹⁰ (may be indicated as “1.0E + 10”) or less. Yes, preferably 1.0 × 10 ^{6 to} 5.0 × 10 ⁹ , more preferably 1.0 × 10 ^{7 to} 4.0 × 10 ⁹ , and even more preferably 3.0 × 10. ⁷ to 3.0 is a × 10 ^9. A surface protective film exhibiting a surface resistance value within the above range can be suitably used as a surface protective film used in a process of processing or transporting an article that dislikes static electricity, such as a liquid crystal cell or a semiconductor device. Further, for the surface protective film showing the surface resistance value within the above range, the operation can be confirmed even when the polarizing plate is mounted on the touch panel sensor and the surface protective film is attached on the polarizing plate. It can be and will be useful. The surface resistance value can be calculated from the surface resistance value measured in an atmosphere of 23 ° C. and 50% RH using a commercially available insulation resistance measuring device (resistivity meter or the like).

<Adhesive layer>
The surface protective film of the present invention has an antistatic layer on at least one surface of the base material, and an adhesive containing a (meth) acrylic polymer on the side of the antistatic layer opposite to the surface in contact with the base material. It is characterized by having a pressure-sensitive adhesive layer formed by the composition.

As the (meth) acrylic polymer, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used as a raw material monomer constituting the polymer. As the (meth) acrylic monomer, one kind or two or more kinds can be used as a main component. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it becomes easy to control the adhesive force to the adherend (protected body) to be low, and light peeling property and re-peeling property can be easily performed. A surface protective film having excellent properties can be obtained. 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 methacrylate.

Specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth). ) Acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl ( Examples include meta) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Be done.

Among them, the surface protective film of the present invention includes hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, and isononyl. (Meta) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, etc. having 6 to 14 carbon atoms. A (meth) acrylic monomer having an alkyl group is preferable. In particular, by using a (meth) acrylic monomer having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the adhesive force to the adherend to be low, and the removability becomes excellent.

In particular, it is preferable to contain 60% by mass or more of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms with respect to 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. , More preferably 70% by mass or more, further preferably 80% by mass or more, and most preferably 90 to 99% by mass. If it is less than 60% by mass, the appropriate wettability of the pressure-sensitive adhesive composition and the cohesive force of the pressure-sensitive adhesive layer will be inferior, which is not preferable.

Further, in the pressure-sensitive adhesive composition of the present invention, it is preferable that the (meth) acrylic polymer contains a (meth) acrylic monomer having a hydroxyl group as a raw material monomer. As the (meth) acrylic monomer having a hydroxyl group, one kind or two or more kinds can be used as a main component.

By using the (meth) acrylic monomer having a hydroxyl group, it becomes easy to control cross-linking of the pressure-sensitive adhesive composition, and by extension, it becomes easy to control the balance between the improvement of wettability due to flow and the reduction of adhesive force in peeling. Become.

Examples of the (meth) acrylic monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth). Examples thereof include acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, and N-methylol (meth) acrylamide. .. In particular, it is preferable to use a (meth) acrylic monomer having a hydroxyl group having 4 or more carbon atoms in the alkyl group, because light peeling at the time of high-speed peeling becomes easy.

It is preferable and more preferable to contain 15 parts by mass or less of the (meth) acrylic monomer having a hydroxyl group with respect to 100 parts by mass of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms. Is 1 to 13 parts by mass, more preferably 2 to 12 parts by mass, and most preferably 3 to 10 parts by mass. When it is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the obtained pressure-sensitive adhesive layer, which is preferable.

In addition, as other polymerizable monomer components, the Tg is set to 0 ° C. or lower (usually -100 ° C. or higher) so that the adhesive performance can be easily balanced, and the glass transition temperature and peeling of the (meth) acrylic polymer are adjusted. A polymerizable monomer for adjusting the property can be used as long as the effect of the present invention is not impaired.

Examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer and other polymerizable monomers other than the (meth) acrylic monomer having a hydroxyl group include , A (meth) acrylic monomer having a carboxyl group can be used.

Examples of the (meth) acrylic monomer having a carboxyl group include (meth) acrylic acid, carboxylethyl (meth) acrylate, and carboxylpentyl (meth) acrylate.

The (meth) acrylic monomer having a carboxyl group is preferably contained in an amount of 20 parts by mass or less, more preferably 20 parts by mass or less, based on 100 parts by mass of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms. Is 1 to 18 parts by mass, more preferably 2 to 16 parts by mass, and most preferably 3 to 14 parts by mass. When it is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the obtained pressure-sensitive adhesive layer, which is preferable.

In particular, when the pressure-sensitive adhesive layer is applied to a polarizing plate having a reduced reflectance (for example, 1.0% or less), the (meth) acrylic monomer having a carboxyl group has 1 to 14 carbon atoms. It is preferably contained in an amount of 3 to 14 parts by mass with respect to 100 parts by mass of the (meth) acrylic monomer having a certain alkyl group. When it is within the above range, the cohesive force of the obtained pressure-sensitive adhesive layer can be controlled to be high, and the contamination by the pressure-sensitive adhesive layer can be controlled to be low with respect to the polarizing plate having low reflectance, which is preferable.

Further, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the (meth) acrylic monomer having a hydroxyl group, and the (meth) having a carboxyl group used in the (meth) acrylic polymer. As the polymerizable monomer other than the acrylic monomer, it can be used without particular limitation as long as it does not impair the characteristics of the present invention. For example, a cohesiveness / heat resistance improving component such as a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, and N-acryloylmorpholin. , Vinyl ether monomer and other components having a functional group that acts as an adhesive strength improving or cross-linking base point can be appropriately used. These polymerizable monomers may be used alone or in combination of two or more.

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

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

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

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylicamide, N, N-diethylacrylamide, N, N-diethylmethacryl. Examples thereof include amide, N, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropylmethacrylamide and diacetoneacrylamide.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like.

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

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

In the present invention, other polymerizable monomers other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the (meth) acrylic monomer having a hydroxyl group, and the (meth) acrylic monomer having a carboxyl group The content is preferably 0 to 20 parts by mass, and more preferably 0 to 10 parts by mass with respect to 100 parts by mass of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms. It is preferable to keep the composition within the above range because good removability can be appropriately adjusted.

The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, and even more preferably 300,000 to 3,000,000. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer is reduced, which tends to cause adhesive residue. On the other hand, when the weight average molecular weight exceeds 5 million, the fluidity of the polymer decreases, the wetness to the adherend (for example, the polarizing plate) becomes insufficient, and the adherend and the pressure-sensitive adhesive layer of the surface protective film Tends to cause blisters that occur during. The weight average molecular weight (Mw) is obtained by measuring by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower (usually −100 ° C. or higher). When the glass transition temperature is higher than 0 ° C., the polymer does not easily flow, for example, the polarizing plate is not sufficiently wetted, which tends to cause blisters generated between the polarizing plate and the pressure-sensitive adhesive layer of the surface protective film. There is. In particular, when the glass transition temperature is set to −61 ° C. or lower, it becomes easy to obtain an adhesive layer having excellent wettability to a polarizing plate and light peelability. The glass transition temperature of the (meth) acrylic polymer can be adjusted within the above range by appropriately changing the monomer component and composition ratio used.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic polymer is 6 or less, preferably 1 to 6, and more preferably 2 to 5. When the molecular weight distribution (Mw / Mn) exceeds 6, the number of low molecular weight components increases, and it is necessary to use a large amount of cross-linking agent in order to increase the gel fraction of the pressure-sensitive adhesive layer. On the other hand, the excess cross-linking agent reacts and the cross-linking density of the gel (adhesive layer) becomes high, which makes the adhesive layer hard and impairs the stress relaxation property, which is not preferable. In addition, when the amount of low molecular weight components is large and the amount of uncrosslinked polymer or oligomer (sol content) is large, the uncrosslinked polymer segregated near the interface of the pressure-sensitive adhesive layer in contact with the adherend (platelet, etc.) causes. , A fragile layer is formed in the pressure-sensitive adhesive layer (particularly the surface of the pressure-sensitive adhesive layer), and when the pressure-sensitive adhesive layer is exposed to a heated / humid environment, the pressure-sensitive adhesive layer is destroyed in the vicinity of the fragile layer, resulting in adhesion. It is presumed that it causes peeling at the interface between the agent layer and the antistatic layer. Further, when the number of low molecular weight components increases, the stain resistance is inferior, but by adjusting the molecular weight distribution to 6 or less, the low molecular weight components transferred to the adherend (polarizing plate, etc.) can be reduced, and the stain resistance can be reduced. It is excellent in the above and is a preferable embodiment. Similar to the weight average molecular weight (Mw), the molecular weight distribution (Mw / Mn) is measured by GPC (gel permeation chromatography) and obtained from a value calculated by polystyrene conversion.

For the production of such (meth) acrylic polymers, known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. Among them, solution polymerization is easy and versatile. It is preferable, and living radical polymerization is preferable because it can suppress the formation of low molecular weight oligomers and secure productivity even when the polymerization rate is increased. Further, the obtained (meth) acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer and the like.

In solution polymerization, for example, ethyl acetate, toluene and the like are used as the polymerization solvent. As a specific example of solution polymerization, the reaction is carried out under the reaction conditions of about 10 minutes to 30 hours at about 50 to 70 ° C. by adding a polymerization initiator under an inert gas stream such as nitrogen. In particular, by shortening the polymerization time to about 30 minutes to 3 hours, it is possible to improve the adhesive reliability of the pressure-sensitive adhesive by suppressing the formation of low molecular weight oligomers produced in the latter stage of polymerization.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. The weight average molecular weight of the (meth) acrylic polymer can be controlled by the amount of the polymerization initiator and the chain transfer agent used, and the reaction conditions, and the amount of the (meth) acrylic polymer used is appropriately adjusted according to these types.

The polymerization initiator is not particularly limited, and examples thereof include peroxide-based polymerization initiators and azo-based polymerization initiators. The peroxide-based polymerization initiator is not particularly limited, and examples thereof include peroxycarbonate, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, and peroxy ester. More specifically, benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis (t-butyl peroxy)-. Examples thereof include 3,3,5-trimethylcyclohexane and 1,1-bis (t-butylperoxy) cyclododecane. The azo-based polymerization initiator is not particularly limited, but for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, and 2,2'-azobis (2). , 4-Dimethylvaleronitrile), 2,2'azobis (2-methylpropionic acid) dimethyl, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane) -1-Carbonitrile), 2,2'-azobis (2,4,4-trimethylpentane), 4,4'-azobis-4-cyanovalerian acid, 2,2'-azobis (2-amidinopropane) dihydro Chloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2' Examples thereof include -azobis (N, N'-dimethyleneisobutyamidin) hydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropion amidine] hydrate and the like. The polymerization initiator may be used alone or in combination of two or more.

Further, as a polymerization initiator used for living radical polymerization, an organic tellurium compound can be mentioned. Examples of the organic tellurium compound include (methylteranyl-methyl) benzene, (1-methylteranyl-ethyl) benzene, (2-methylteranyl-propyl) benzene, 1-chloro-4- (methylteranyl-methyl) benzene, and 1-hydroxy-. 4- (Methylteranyl-methyl) benzene, 1-methoxy-4- (methylteranyl-methyl) benzene, 1-amino-4- (methylteranyl-methyl) benzene, 1-nitro-4- (methylteranyl-methyl) benzene, 1- Cyan-4- (methylteranyl-methyl) benzene, 1-methylcarbonyl-4- (methylteranyl-methyl) benzene, 1-phenylcarbonyl-4- (methylteranyl-methyl) benzene, 1-methoxycarbonyl-4- (methylteranyl-methyl) ) Benzene, 1-phenoxycarbonyl-4- (methylteranyl-methyl) benzene, 1-sulfonyl-4- (methylteranyl-methyl) benzene, 1-trifluoromethyl-4- (methylteranyl-methyl) benzene, 1-chloro-4 -(1-Methylteranyl-ethyl) benzene, 1-hydroxy-4- (1-methylteranyl-ethyl) benzene, 1-methoxy-4- (1-methylteranyl-ethyl) benzene, 1-amino-4- (1-methylteranyl) -Ethyl) benzene, 1-nitro-4- (1-methylteranyl-ethyl) benzene, 1-cyano-4- (1-methylteranyl-ethyl) benzene, 1-methylcarbonyl-4- (1-methylteranyl-ethyl) benzene , 1-Phenylcarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-methoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-phenoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1, -Sulfonyl-4- (1-methylteranyl-ethyl) benzene, 1-trifluoromethyl-4- (1-methylteranyl-ethyl) benzene, 1-chloro-4- (2-methylteranyl-propyl) benzene, 1-hydroxy- 4- (2-Methylteranyl-propyl) benzene, 1-methoxy-4- (2-methylteranyl-propyl) benzene, 1-amino-4- (2-methylteranyl-propyl) benzene, 1-nitro-4- (2-) Methylteranyl-propyl) benzene, 1-cyano-4- (2-methylteranyl-propyl) benzene, 1-methylcarbonyl-4- (2-methylteranyl-propyl) ) Benzene, 1-phenylcarbonyl-4- (2-methylteranyl-propyl) benzene, 1-methoxycarbonyl-4- (2-methylteranyl-propyl) benzene, 1-phenoxycarbonyl-4- (2-methylteranyl-propyl) benzene , 1-sulfonyl-4- (2-methylteranyl-propyl) benzene, 1-trifluoromethyl-4- (2-methylteranyl-propyl) benzene, 2- (methylteranyl-methyl) pyridine, 2- (1-methylteranyl-ethyl) ) Pyridine, 2- (2-methylteranyl-propyl) pyridine, 2-methylteranyl-methyl ethaneate, methyl 2-methylteranyl-propionate, methyl 2-methylteranyl-2-methylpropionate, ethyl 2-methylteranyl-ethylethanate, 2 Ethyl methylteranyl-propionate, ethyl 2-methyl-2-methylteranyl-propionate, 2-methylteranyl acetonitrile, 2-methylteranylpropionitrile, 2-methyl-2-methylteranylpropionitrile, etc. Be done. The methylteranyl group in these organotellurium compounds may be an ethylteranyl group, an n-propylteranyl group, an isopropylteranyl group, an n-butylteranyl group, an isobutylteranyl group, a t-butylteranyl group, a phenylteranyl group or the like. Good. The polymerization initiator may be used alone or in combination of two or more.

The blending ratio of the polymerization initiator (total polymerization initiator) is not particularly limited, but for example, 0.005 to 5 mass by mass with respect to the total amount (100 parts by mass) of the monomer components constituting the (meth) acrylic polymer. Parts are preferable, and more preferably 0.01 to 3 parts by mass.

<Crosslinking agent>
In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a cross-linking agent. Further, in the present invention, the pressure-sensitive adhesive composition can be used to form a pressure-sensitive adhesive layer. For example, a surface protective film (adhesive layer) having more excellent heat resistance can be obtained by appropriately adjusting the structural unit, composition ratio, selection of cross-linking agent, addition ratio, etc. of the (meth) acrylic polymer and cross-linking. be able to.

As the cross-linking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound and the like may be used, and the use of the isocyanate compound is particularly preferable. Further, 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 dimerate diisocyanate, and fats such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate (IPDI). Arophanic isocyanates such as cyclic isocyanates, 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI), and the isocyanate compounds are allophanate bond, biuret bond, isocyanurate bond, uretdione bond. , Urea bond, carbodiimide bond, uretonimine bond, oxadiazine trione bond and the like modified polyisocyanate modified product. For example, as commercial products, trade names Takenate 300S, Takenate 500, Takenate D165N, Takeda D178N (above, manufactured by Takeda Pharmaceutical Company Limited), Sumijuru T80, Sumijuru L, Death Module N3400 (above, manufactured by Sumika Bayer Urethane Co., Ltd.). , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like. These isocyanate compounds may be used alone or in combination of two or more, or a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a cross-linking agent in combination, it is possible to achieve both adhesiveness and resilience (adhesiveness to a curved surface), and a surface protective film having more excellent adhesive reliability can be obtained.

Examples of the epoxy compound include N, N, N', N'-tetraglycidyl-m-xylene diamine (trade name: TETRAD-X, manufactured by Mitsubishi Gas Chemical Company, Inc.) and 1,3-bis (N, N-diamine). Glycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) and the like can be mentioned.

Examples of the melamine-based resin include hexamethylol melamine and the like. Examples of the aziridine derivative include commercially available commercial products such as HDU, TAZM, and TAZO (all manufactured by Mutual Pharmaceutical Co., Ltd.).

Examples of the metal chelate compound include aluminum, iron, tin, titanium, nickel and the like as metal components, and acetylene, methyl acetoacetate, ethyl lactate and the like as chelate components.

The content of the cross-linking agent used in the present invention is preferably 0.01 to 20 parts by mass, preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer. It is more preferably contained, more preferably 0.5 to 8 parts by mass, and most preferably 1 to 6 parts by mass. If the content is less than 0.01 parts by mass, the cross-linking by the cross-linking agent is insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer is reduced, and sufficient heat resistance may not be obtained. It tends to cause adhesive residue. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, the fluidity is lowered, the wettability to the adherend (for example, the polarizing plate) is insufficient, and the adherend and the pressure-sensitive adhesive are used. It tends to cause blisters that occur between the layer (adhesive composition layer). Further, if the amount of the cross-linking agent is large, the peeling charging property tends to be deteriorated.

In particular, when the pressure-sensitive adhesive layer is applied to a polarizing plate having a reduced reflectance (for example, 1.0% or less), an epoxy compound is effective as the cross-linking agent, and the content of the epoxy compound is the above. It is preferably contained in an amount of 3 to 17 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. When it is within the above range, the cohesive force of the obtained pressure-sensitive adhesive layer can be controlled to be high, and the contamination by the pressure-sensitive adhesive layer can be controlled to be low with respect to the polarizing plate having low reflectance, which is preferable.

<Crosslink catalyst>
The pressure-sensitive adhesive composition may further contain a cross-linking catalyst for more effectively advancing any of the above-mentioned cross-linking reactions. Examples of such cross-linking catalysts include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris (acetylacetonato) iron, tris (hexane-2,4-dionat) iron, and tris (heptane-2,4-dionat). Iron, Tris (Heptane-3,5-Zionato) Iron, Tris (5-Methylhexane-2,4-Zionato) Iron, Tris (Octane-2,4-Zionato) Iron, Tris (6-Methylheptane-2, 4-Zionato iron, Tris (2,6-dimethylheptane-3,5-Zionato) iron, Tris (Nonan-2,4-Zionato) iron, Tris (Nonan-4,6-Zionato) iron, Tris (2) , 2,6,6-tetramethylheptane-3,5-dionat) iron, tris (tridecane-6,8-dionat) iron, tris (1-phenylbutane-1,3-dionat) iron, tris (hexafluoro) Acetylacetonato iron, tris (ethylacetate acetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropylacetate isopropyl) iron, tris (acetoacetate-n-butyl) iron, tris (acetoacetic acid-sec) -Butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (propionylmethylacetate) iron, tris (propionylacetate ethyl) iron, tris (propionylacetate-n-propyl) iron, tris (propionylacetate isopropyl) iron , Tris (propionyl acetate-n-butyl) iron, tris (propionyl acetate-sec-butyl) iron, tris (propionyl acetate-tert-butyl) iron, tris (benzyl acetoacetate) iron, tris (dimethyl malonate) iron, Iron-based catalysts such as tris (diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, and ferric chloride can be used. These cross-linking catalysts may be used alone or in combination of two or more.

The content (usage amount) of the cross-linking catalyst is not particularly limited, but is preferably 0.0001 to 1 part by mass, and 0.001 to 0.5 parts by mass, for example, with respect to 100 parts by mass of the (meth) acrylic polymer. Parts by mass are more preferred. When it is within the above range, the rate of the cross-linking reaction becomes high when the pressure-sensitive adhesive layer is formed, which is a preferable embodiment.

<Crosslink retarder>
The pressure-sensitive adhesive composition may further contain a cross-linking retarder. The cross-linking retarder is not particularly limited, and for example, β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, acetylacetone, 2,4- Examples thereof include β-diketone such as hexanedione and benzoylacetone, and isopropyl alcohol. Among them, acetylacetone can be used. The cross-linking retarder can be used alone or in combination of two or more.

The content (usage amount) of the cross-linking retarder is not particularly limited, but is preferably 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass (when converted to) of the solvent, for example. More preferred. When it is within the above range, the pot life of the pressure-sensitive adhesive (pressure-sensitive adhesive composition) can be extended, which is a preferable embodiment.

The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention may further contain a solvent. Examples of the solvent include the solvent used in the above-mentioned solution polymerization method. The solvent in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention may be the same as or different from the solvent used in the solution polymerization method. The solvent in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention can be used alone or in combination of two or more.

Further, the pressure-sensitive adhesive composition may contain other known additives as long as the properties such as stain resistance can be satisfied, and for example, powders such as colorants and pigments, and surfactants. , Plasticizers, tackifiers, low molecular weight polymers, surfactants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillings It can be appropriately added depending on the intended use of the agent, metal powder, particles, foil or the like.

<Adhesive layer / surface protection film>
The surface protective film of the present invention has an antistatic layer on at least one surface of a base material, and an adhesive containing a (meth) acrylic polymer on the side of the antistatic layer opposite to the surface in contact with the base material. It has a pressure-sensitive adhesive layer formed by the composition (base material / antistatic layer / pressure-sensitive adhesive layer), but in that case, the cross-linking of the pressure-sensitive adhesive composition is generally performed after application of the pressure-sensitive adhesive composition. However, it is also possible to transfer the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition after cross-linking to a substrate or the like.

The method of forming the pressure-sensitive adhesive layer on the antistatic layer is not particularly limited. For example, the antistatic agent composition (solution) is applied to a base material, and a polymerization solvent or the like is dried and removed to remove the antistatic layer. Can be formed by forming the adhesive composition on a base material and applying and drying the pressure-sensitive adhesive composition on the prepared antistatic layer. As another method, the antistatic agent composition (solution) is applied to a base material, a polymerization solvent or the like is dried and removed to form an antistatic layer on the base material, and a pressure-sensitive adhesive composition is separately provided. It can also be formed by applying and drying on a separator to form a pressure-sensitive adhesive layer, and transferring the pressure-sensitive adhesive layer onto an antistatic layer.

Further, as a method for forming the pressure-sensitive adhesive layer when manufacturing the surface protective film of the present invention, a known method used for manufacturing pressure-sensitive adhesive tapes is used. Specific examples thereof include a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method, and an extrusion coat method using a die coater or the like.

The surface protective film of the present invention is usually prepared so that the thickness of the pressure-sensitive adhesive layer is preferably 3 to 100 μm, more preferably about 5 to 50 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is easy to obtain an appropriate balance between removability and adhesiveness, which is preferable.

The surface protective film of the present invention preferably has a total thickness of 1 to 400 μm, more preferably 10 to 200 μm, and even more preferably 20 to 100 μm. When it is within the above range, it is excellent in adhesive properties (removability, adhesiveness, etc.), workability, and appearance characteristics, and is a preferable embodiment. The total thickness means the total thickness including all layers such as the base material, the pressure-sensitive adhesive layer, and the antistatic layer.

<Separator>
In the surface protective film of the present invention, a separator can be attached to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface, if necessary.

Paper and a plastic film are examples of the material constituting the separator, and the plastic film is preferably used because of its excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and is, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-weight. Examples thereof include a coalesced film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually about 5 to 200 μm, preferably about 10 to 100 μm. When it is within the above range, it is preferable because it is excellent in sticking workability to the pressure-sensitive adhesive layer and peeling workability from the pressure-sensitive adhesive layer. If necessary, the separator may be released from a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agent, silica powder, or the like, as well as a coating type, a kneading type, or a vapor deposition type. It is also possible to carry out antistatic treatment such as.

The surface protective film disclosed herein can also be implemented in an embodiment that includes, in addition to the base material, the antistatic layer, and the pressure-sensitive adhesive layer, yet another layer. Examples of such an arrangement of the "other layer" include the space between the base material and the antistatic layer.

<Optical member>
The optical member of the present invention is preferably protected by the surface protective film. The surface protective film has excellent anchoring properties for the antistatic layer of the adhesive layer, and also has excellent peeling antistatic properties and stain resistance. Therefore, the surface protective film is used for surface protection during processing, transportation, shipping inspection, etc. (Surface protective film). ), And it is useful for protecting the surface of the optical member (polarizing plate, etc.) from scratches and contamination. In particular, since it can be used for plastic products that easily generate static electricity, it is very useful for antistatic applications in the technical fields related to optical and electronic components where charging is a particularly serious problem.

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in such specific examples. In addition, "part" and "%" in the following description are based on mass unless otherwise specified. In addition, the blending amount (used amount) in the table indicates the solid content, the solid content ratio, or the active ingredient.

In addition, each characteristic in the following description was measured or evaluated as follows.

<Measurement of glass transition temperature (Tg) of (meth) acrylic polymer>
The glass transition temperature Tg (° C.) was determined by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer by each monomer.
Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
In the formula, Tg (° C.) is the glass transition temperature of the copolymer, Wn (-) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer by each monomer, and n is the type of each monomer. Represent.
Reference value:
Butyl acrylate (BA): -55 ° C
2-Ethylhexyl acrylate (2EHA): -70 ° C
4-Hydroxybutyl acrylate (4HBA): −32 ° C.
Acrylic acid (AA): 106 ° C

<Measurement of weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of (meth) acrylic polymer>
The weight average molecular weight (Mw) of the (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The molecular weight distribution (Mw / Mn) of the (meth) acrylic polymer was also measured in the same manner.
-Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
-Column: Made by Tosoh, G7000HXL + GMHXL + GMHXL
-Column size: 7.8 mm φ x 30 cm each, 90 cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8 mL / min
・ Injection amount: 100 μL
-Eluent: 10 mM-phosphoric acid / tetrahydrofuran-Detector: differential refractometer (RI)
・ Standard sample: Polystyrene

<Measurement of surface resistance>
The measurement was performed according to JIS-K-6911 using a resistivity meter (manufactured by Mitsubishi Chemical Analytical Co., Ltd., Hiresta UP MCP-HT450 type) in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH. The applied voltage was 100 V, and the surface resistance value was read 10 seconds after the start of measurement. Further, the surface resistance value (Ω / □) measured on the surface of the antistatic layer in the present invention is obtained by applying the antistatic agent composition (solution) to the substrate and drying it to form the antistatic layer. The measurement was performed in a state where the antistatic layer was exposed before the pressure-sensitive adhesive composition was applied to the surface of the prevention layer or the pressure-sensitive adhesive layer was formed.

The surface resistance value (Ω / □) measured on the surface of the antistatic layer in the present invention is 1.0 × 10 ¹⁰ (1.0E + 10) or less, preferably 1.0 × 10 ^{6 to} 5. It is .0 × 10 ⁹ , more preferably 1.0 × 10 ^{7 to} 4.0 × 10 ⁹ , and even more preferably 3.0 × 10 ^{7 to} 3.0 × 10 ⁹ . A surface protective film having an antistatic layer showing a surface resistance value within the above range is suitable as a surface protective film used in a process of processing or transporting an article that dislikes static electricity, such as a liquid crystal cell or a semiconductor device. Can be used. Further, for the surface protective film showing the surface resistance value within the above range, the operation can be confirmed even when the polarizing plate is mounted on the touch panel sensor and the surface protective film is attached on the polarizing plate. It can be and will be useful.

<Water contact angle>
After attaching the surface protection film to the surface of glass (manufactured by Matsunami Glass Industry Co., Ltd., trade name "GRILLA3 reinforced product"), it was put into an autoclave, heated at a temperature of 150 ° C. for 30 minutes, and a sample that was in close contact was taken out. After allowing to cool at 23 ° C. for 30 minutes, the surface protective film was peeled off from the glass surface. Then, using a water contact angle measuring device (trade name "DM700", manufactured by Kyowa Interface Chemical Co., Ltd.), a glass to which a surface protective film was attached was applied in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH by a liquid method. Approximately 2.8 μL of water droplets are dropped on the surface of the (attached body), and the angle consisting of the tangent line between the surface of the adherend and the end of the dropped water drops 1 second after the dropping is measured, and the “water contact angle (°)” is measured. And said.
When the difference between the water contact angle and the water contact angle of untreated glass (blank, manufactured by Matsunami Glass Ind., Trade name "GRILLA3 reinforced product") is 50 ° or less, "(contamination resistance)". When the property was (◯) ”and larger than 50 °, it was evaluated as“ (stain resistance) poor (×) ”.
The water contact angle of the blank (adhesive body) that had not been treated was 21 °. That is, the adherend used in this evaluation is glass having a water contact angle of 21 ° (see Table 2).

<Measurement of peeling band voltage (polarizing plate side)>
The surface protective film 1 according to each example was cut into a size of 70 mm in width and 130 mm in length, the release liner was peeled off, and then, as shown in FIG. 2, the acrylic plate 10 (manufactured by Mitsubishi Rayon Co., Ltd.) was previously statically eliminated. On the surface of the polarizing plate 20 (manufactured by Nitto Denko, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) bonded to the product name "Acrylite", thickness: 1 mm, width: 70 mm, length: 100 mm). The surface protective film 1 was pressure-bonded with a hand roller so that one end of the surface protective film 1 protruded 30 mm from the end of the polarizing plate 20.
This sample was left in an environment of 23 ° C. × 50% RH for one day, and then set in a predetermined position on a sample fixing table 30 having a height of 20 mm. The end portion of the surface protective film 1 protruding 30 mm from the polarizing plate 20 was fixed to an automatic winder (not shown) and peeled so as to have a peeling angle of 150 ° and a peeling speed of 10 m / min. The potential of the surface of the adherend (polarizing plate) generated at this time is fixed at a position 100 mm in height from the center of the polarizing plate 20 (manufactured by Kasuga Electric Co., Ltd., model “KSD-0103”). The stripping band voltage was measured at. The measurement was performed in an environment of 23 ° C. and 50% RH.

The peeling band voltage is a peeling band voltage derived from the antistatic layer constituting the surface protective film of the present invention, and contributes to the peeling antistatic property.

The peeling band voltage (kV) (absolute value) in the present invention is preferably 1.0 kV or less, more preferably 0.9 kV or less, and further preferably 0.8 kV or less. When it is within the above range, for example, damage to the liquid crystal driver or the like can be prevented, which is a preferable embodiment. When the peeling band voltage (kV) (absolute value) was 1.0 kV or less, it was evaluated as ◯ (good peeling antistatic property), and when it exceeded 1.0 kV, it was evaluated as × (poor peeling antistatic property). See Table 2).

<Anchoring property of the adhesive layer to the antistatic layer>
The surface of the adhesive layer of the surface protective film was thinly scratched with a cutter, and a tape (manufactured by Nitto Denko Corporation, trade name "Dumplon Tape No. 375") was attached from above with a hand roller. Subsequently, after peeling off the tape, the surface of the pressure-sensitive adhesive layer is visually checked, and if the pressure-sensitive adhesive layer and the antistatic layer are in close contact with each other, ○ (excellent anchoring property), the pressure-sensitive adhesive layer is detached from the antistatic layer. If so, it was evaluated as × (poor anchorability) (see Table 2).

<Example 1>
[Preparation of (meth) acrylic polymer for adhesive layer]
95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), 2,2'-azo as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. 0.2 parts by mass of bisisobutyronitrile (AIBN) and 234 parts by mass of ethyl acetate were charged, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65 ° C. for a 6-hour polymerization reaction. This was performed to prepare a (meth) acrylic polymer solution (30% by mass). The weight average molecular weight (Mw) of the (meth) acrylic polymer was 600,000, the molecular weight distribution (Mw / Mn) was 4.0, and the glass transition temperature (Tg) was −47 ° C.

[Preparation of acrylic adhesive solution]
The (meth) acrylic polymer solution (30% by mass) was diluted with ethyl acetate to 20% by mass, and an epoxy-based cross-linking agent (Mitsubishi Gas Chemicals) was added to 500 parts by mass (solid content 100 parts by mass) of this solution as a cross-linking agent. Made by Co., Ltd., trade name "Tetrad-C", 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, number of functional groups: 4) 6 parts by mass (solid content 6 parts by mass) As a cross-linking retarder, 10 parts by mass of isopropyl alcohol was added to 100 parts by mass of the solvent (when converted), and the mixture was mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution (tack agent composition).

[Preparation of aqueous solution for antistatic layer]
Polyester resin bironal MD-1480 (25% aqueous solution, manufactured by Toyo Boseki Co., Ltd.) as a binder, poly (3,4-ethylenedioxythiophene) (PEDOT) 0.5% and polystyrene sulfonate (weight average) as a conductive polymer. An aqueous solution (Bytron P, manufactured by HC Stark) containing 0.8% of a molecular weight of 150,000) (PSS) was used as a mixed solvent of water / ethanol (1/1), and a binder was used as a solid content of 100 parts by mass. 50 parts by mass of the conductive polymer and 20 parts by mass of the melamine-based cross-linking agent were added in terms of solid content, and the mixture was sufficiently mixed by stirring for about 20 minutes. In this way, an aqueous solution for an antistatic layer (antistatic agent composition) having an NV of about 0.4% was prepared.

[Preparation of substrate with antistatic layer]
As a base material, the aqueous solution for an antistatic layer is applied to a corona-treated surface of a transparent polyethylene terephthalate (PET) film (polyester film) having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, which is corona-treated on one surface. , The film was applied so that the thickness after drying was 10 nm. The coated material was heated to 130 ° C. for 1 minute and dried to prepare a base material with an antistatic layer having an antistatic layer on one side of the PET film.

[Preparation of surface protection film]
The acrylic pressure-sensitive adhesive solution is applied to the surface of the base material with an antistatic layer in contact with the base material, and heated at 130 ° C. for 30 seconds to form a pressure-sensitive adhesive layer having a thickness of 5 μm. did. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm), which is a separator treated with silicone on one side, was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protective film with a separator.

<Example 2>
[Preparation of (meth) acrylic polymer for adhesive layer]
The formulation contents in Table 1 were prepared in the same manner as in Example 1.

[Preparation of acrylic adhesive solution]
The (meth) acrylic polymer solution (30% by mass) was diluted with ethyl acetate to 20% by mass, and an isocyanurate form of hexamethylene diisocyanate (isocyanurate) was added to 500 parts by mass (solid content 100 parts by mass) of this solution as a cross-linking agent. Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd. 6 parts by mass (solid content 6 parts by mass), dibutyltin dilaurate (trade name: OL-1, manufactured by Tokyo Fine Chemicals Co., Ltd.) (1 mass% ethyl acetate solution) 3 mass as a cross-linking catalyst Add 3 parts by mass of acetylacetone to 100 parts by mass (when converted) of the solvent as a cross-linking retarder and mix and stir to prepare an acrylic pressure-sensitive adhesive solution. did.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Example 3>
[Preparation of (meth) acrylic polymer for adhesive layer: living radical polymerization]
In a glove box substituted with argon, 0.035 parts by mass of ethyl 2-methyl-2-n-butylteranyl-propionate, 2, as an organic tellurium compound which is a polymerization initiator used for living radical polymerization, is placed in a reaction vessel. After adding 0.0025 parts by mass of 2'-azobisisobutyronitrile and 1 part by mass of ethyl acetate, the reaction vessel was sealed and the reaction vessel was taken out from the glove box.
Subsequently, while flowing argon gas into the reaction vessel, 100 parts by mass of butyl acrylate (BA), 4 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 50 parts by mass of ethyl acetate as a polymerization solvent were added into the reaction vessel. Then, the liquid temperature in the reaction vessel was maintained at around 60 ° C. and the polymerization reaction was carried out for 20 hours to prepare a (meth) acrylic polymer solution (20% by mass). The weight average molecular weight (Mw) of the (meth) acrylic polymer was 800,000, the molecular weight distribution (Mw / Mn) was 2.5, and the glass transition temperature (Tg) was −54 ° C.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 2.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Example 4>
[Preparation of (meth) acrylic polymer for adhesive layer]
The formulation contents in Table 1 were prepared in the same manner as in Example 1.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 2.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Example 5>
[Preparation of (meth) acrylic polymer for adhesive layer]
The formulation contents in Table 1 were prepared in the same manner as in Example 1.

[Preparation of acrylic adhesive solution]
The formulation contents in Table 1 were prepared in the same manner as in Example 1.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Example 6>
[Preparation of (meth) acrylic polymer for adhesive layer]
It was prepared in the same manner as in Example 5.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 5.

[Preparation of aqueous solution for antistatic layer]
Polyester resin bironal MD-1480 (25% aqueous solution, manufactured by Toyo Boseki Co., Ltd.) as a binder, polyaniline sulfonic acid (aquaPASS, weight average molecular weight 40,000, manufactured by Mitsubishi Rayon Co., Ltd.) as a conductive polymer, and diisopropylamine as a cross-linking agent. Isocyanurate of blocked hexamethylene diisocyanate, as a lubricant, oleic acid amide in a mixed solvent of water / ethanol (1/3), binder in 100 parts by mass in solid content, conductive polymer in 75 parts by mass in solid content, 10 parts by mass of the cross-linking agent and 30 parts by mass of the lubricant were added, and the mixture was stirred for about 20 minutes and sufficiently mixed. In this way, an aqueous solution for an antistatic layer (antistatic agent composition) having an NV of about 0.4% was prepared.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Comparative example 1>
[Preparation of (meth) acrylic polymer for adhesive layer]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), and benzoyl peroxide 0.2 as a polymerization initiator. A part by mass and 43 parts by mass of ethyl acetate were charged, nitrogen gas was introduced while gently stirring, and the polymerization reaction was carried out for 6 hours while keeping the liquid temperature in the flask at around 65 ° C. to obtain a (meth) acrylic polymer solution (70). (% by mass) was prepared, and then diluted with ethyl acetate to prepare a (meth) acrylic polymer solution (30% by mass). The weight average molecular weight (Mw) of the (meth) acrylic polymer was 1.1 million, the molecular weight distribution (Mw / Mn) was 13.0, and the glass transition temperature (Tg) was −47 ° C.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 1.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Comparative example 2>
[Preparation of (meth) acrylic polymer for adhesive layer]
It was prepared in the same manner as in Example 1.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 1.

[Preparation of aqueous solution for antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of substrate with antistatic layer]
As a base material, the aqueous solution for an antistatic layer is applied to a corona-treated surface of a transparent polyethylene terephthalate (PET) film (polyester film) having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, which is corona-treated on one surface. , The film was applied so that the thickness after drying was 10 nm. The coated material was heated to 130 ° C. for 1 minute and dried to prepare a base material with an antistatic layer having an antistatic layer on one side of the PET film. Then, the surface of the antistatic layer of the base material with the antistatic layer was further irradiated with ultraviolet rays (UV-A) by a UV conveyor (manufactured by Harrison Toshiba Lighting Co., Ltd.) so that the integrated light amount was 1000 mJ / cm ² . The illuminance (1000 mW) was measured using UVPF-A1 (manufactured by Iwasaki Electric Co., Ltd.).

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Comparative example 3>
[Preparation of (meth) acrylic polymer for adhesive layer]
It was prepared in the same manner as in Example 1.

[Preparation of acrylic adhesive solution]
It was prepared in the same manner as in Example 1.

[Preparation of aqueous solution for antistatic layer]
Acrylic resin Aron A-3611 (48% aqueous solution, manufactured by Toa Synthetic Co., Ltd.) as a binder, poly (3,4-ethylenedioxythiophene) (PEDOT) 0.5% and polystyrene sulfonate (3,4-ethylenedioxythiophene) (PEDOT) as a conductive polymer. An aqueous solution (Bytron P, manufactured by HC Stark) containing 0.8% of a weight average molecular weight of 150,000) (PSS) was used as a mixed solvent of water / ethanol (1/1), and a binder was used as a solid content of 100 parts by mass. And 50 parts by mass of the conductive polymer in terms of solid content and 20 parts by mass of the melamine-based cross-linking agent were added, and the mixture was sufficiently mixed by stirring for about 20 minutes. In this way, an aqueous solution for an antistatic layer having an NV of about 0.4% was prepared.

[Preparation of substrate with antistatic layer]
It was prepared in the same manner as in Example 1.

[Preparation of surface protection film]
It was produced in the same manner as in Example 1.

<Examples 2 to 6 and Comparative Examples 1 to 3>
Based on the formulation contents in Table 1, the surface protective film was finally prepared in the same manner as in Example 1 with respect to the preparation conditions and the like.

Table 2 shows the results of the various measurements and evaluations described above for the surface protective films according to Examples and Comparative Examples.

The abbreviations in Table 1 will be described below.
BA: Butyl Acrylate 2EHA: 2-Ethylhexyl Acrylate 4HBA: 4-HydroxyButyl Acrylate AA: Acrylic Acid (AA)
AIBN: 2,2'-azobisisobutyronitrile BPO: Benzoyl peroxide (benzoyl peroxide)
Polyester type (binder): Polyester resin, trade name "Byronal MD-1480" (25% aqueous solution, manufactured by Toyobo Co., Ltd.)
Acrylic (binder): Acrylic resin, trade name "Aron A-3611" (48% aqueous solution, manufactured by Toagosei Co., Ltd.)
PEDOT / PSS complex: Product name "Clevious P" (manufactured by Heraeus)
PEDOT: Poly (3,4-ethylenedioxythiophene)
PSS: Polystyrene sulfonate (weight average molecular weight 150,000)
Polyaniline sulfonic acid: Product name "aquaPASS" (manufactured by Mitsubishi Rayon)

From the above evaluation results, it was confirmed that in all the examples, the stain resistance, the peeling antistatic property, and the anchoring property of the adhesive layer with respect to the antistatic layer were excellent and practical. On the other hand, in Comparative Example 1, it was confirmed that the (meth) acrylic polymer used for the pressure-sensitive adhesive layer was inferior in stain resistance and anchoring property because the molecular weight distribution was out of the desired range. In Comparative Example 2, since the base material with the antistatic layer was irradiated with ultraviolet rays (UV-A), the PSS contained in the antistatic layer was decomposed and reduced in molecular weight, and the interaction with PEDOT was weakened. It was confirmed that the surface resistance value of the antistatic layer was high due to the loss of conductivity of PEDOT, which was out of the desired range, and was also inferior in peeling antistatic property. Further, in Comparative Example 3, since an acrylic-based binder component used for the antistatic layer was used instead of a polyester-based binder, it was confirmed that the adhesive layer was inferior in anchoring property to the antistatic layer.

The surface protective film disclosed herein is optical during manufacturing, transportation, etc. of an optical member such as a polarizing plate used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like. It is suitable as a surface protective film for protecting a member. In particular, it is useful as a surface protective film (optical surface protective film) applied to an optical member such as a polarizing plate mounted on an on-cell type or in-cell type touch panel.

1: Surface protective film 10: Acrylic plate 11: Base material 12: Antistatic layer 13: Adhesive layer 14: Separator 20: Polarizing plate 30: Sample fixing base 40: Potential measuring device

Claims (3)

A pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing an antistatic layer on at least one side of the base material and containing a (meth) acrylic polymer on the side of the antistatic layer opposite to the side in contact with the base material. A surface protective film having a layer
The antistatic layer is formed of an antistatic agent composition containing a water-soluble conductive polymer and / or a water-dispersible conductive polymer and a polyester resin as a binder.
The surface resistance value of the antistatic layer is 1.0 × 10 ¹⁰ Ω / □ or less.
The (meth) molecular weight distribution of the acrylic polymer molecular weight distribution (Mw / Mn) state, and are 6 or less,
The antistatic layer removes a cured product of a polymer composition containing a radical initiator.
A surface protective film , wherein the pressure-sensitive adhesive layer removes a pressure-sensitive adhesive layer formed of a nitrogen-containing acrylic pressure-sensitive adhesive. The surface protective film according to claim 1, wherein the base material is a polyester film. An optical member that is protected by the surface protective film according to claim 1 or 2.

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