TWI811477B - Surface protection film and optical components - Google Patents

Abstract

An object of the present invention is to provide a surface protective film suitable for covering and protecting a surface to be protected having a non-flat portion such as a curved portion or a flexed portion, and an optical member accompanied by such a surface protective film. The film 10 as the surface protective film of the present invention has a laminated structure including a base film 11 and an adhesive layer 12 . The storage elastic modulus of the base film 11 at 130°C is 700 MPa or less, and the storage elastic modulus of the base film 11 at 30°C is more than 1000 MPa. The optical member 20 of the present invention includes the film 10 as a surface protective film.

Description

Surface protective film and optical components

The present invention relates to a surface protective film and an optical member provided with the same.

In recent years, surface protective films with higher transparency have been used in various technical fields. For example, in the technical field of flat panel displays (FPDs), various optical components incorporated into the FPD sometimes have surface protective films attached to their surfaces in order to protect their surfaces during the manufacturing process, inspection steps, transportation processes, etc. Such a surface protective film is described in the following Patent Documents 1 and 2, for example. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2012-17399 Patent Document 2: Japanese Patent Application Publication No. 2016-74899

[Problem to be solved by the invention]

An example of an optical member whose surface is covered and protected by a surface protective film is a transparent covering member such as a cover glass for a display. Cover members for displays and the like may be patterned so as to include uneven portions such as curved portions and deflected portions on the outer surface.

However, there is a case where the conventional surface protection film cannot fully follow the surface shape of the non-flat part (non-flat surface) even if it is tried to be bonded to a surface to be protected including a non-flat part such as a curved part or a flexed part. Shape), and a portion that is not attached to the surface to be protected is produced in the non-flat area. In addition, there is a case where the conventional surface protective film cannot maintain the following shape even when it temporarily follows the non-flat surface shape, and peeling occurs at the non-flat portion.

The present invention was conceived based on the above situation, and aims to provide a surface protective film suitable for covering and protecting a surface to be protected including a non-flat portion such as a curved portion or a flexed portion, and a surface protective film attached thereto. optical components. [Technical means to solve problems]

According to a first aspect of the present invention, a surface protective film is provided. The surface protective film has a laminated structure including a base film and an adhesive layer. The storage elastic modulus (first storage elastic modulus) of the base film at 130°C is 700 MPa or less, preferably 500 MPa or less, more preferably 300 MPa or less, more preferably 200 MPa or less, more preferably 100 MPa or less. MPa or less, more preferably 80 MPa or less. The storage elastic modulus (second storage elastic modulus) of the base film at 30°C is 1000 MPa or more, preferably 1500 MPa or more, more preferably 2000 MPa or more, more preferably 2500 MPa or more, more preferably 2700 MPa or above, more preferably 2800 MPa or above. The storage elastic modulus of the base film at 80° C. is not less than the first storage elastic modulus and not more than the second storage elastic modulus, for example, 700 to 1100 MPa, preferably 700 to 1000 MPa. Moreover, the adhesive layer of this surface protection film contains, for example, an acrylic polymer and/or a urethane polymer as an adhesive. The surface protective film with this structure is used with its adhesive layer side attached to the protected surface of the adherend.

The base material film of this surface protection film is as mentioned above. The storage elastic modulus at 130°C is 700 MPa or less, preferably 500 MPa or less, more preferably 300 MPa or less, more preferably 200 MPa or less, more preferably 100 MPa or less, more preferably 80 MPa or less. This structure is suitable for making the surface of the adherend to be protected including a curved portion or a flexure portion and other uneven portions, so that the surface protective film can follow the unevenness in a state that is sufficiently softened by, for example, heating to about 100°C or above. The surface shape of the part is adhered to one side.

In addition, as mentioned above, the base film of this surface protection film has a storage elastic modulus at 30°C of 1000 MPa or more, preferably 1500 MPa or more, more preferably 2000 MPa or more, more preferably 2500 MPa or more, even more preferably It is 2700 MPa or more, more preferably, it is 2800 MPa or more. This structure is suitable for a surface to be protected by an adherend that contains uneven parts such as curved parts or flexure parts. The surface protective film side is sufficiently softened by heating to about 100°C or above, for example, so that it can follow the surface of the uneven parts. After one side is attached to the surface to be protected, the shape of the surface protection film that follows the shape of the non-flat surface is maintained when the film is cooled to about room temperature.

As described above, this surface protective film is suitable for following the non-flat surface shape in the surface to be protected while being adhered to the surface to be protected in a state that is sufficiently softened by heating to about 100°C or above, for example. : Maintaining the shape following non-flat surface shapes under temperature conditions around room temperature after bonding. This surface protective film is suitable for covering and protecting a surface to be protected that has a non-flat portion such as a curved portion or a flexed portion.

The material constituting the base film preferably contains polyester. This configuration is preferable in that it is easy to achieve better storage elastic modulus (first storage elastic modulus, second storage elastic modulus).

In this surface protection film, the base film preferably has a laminated structure including an antistatic layer. The antistatic layer preferably contains an antistatic agent having a quaternary ammonium group and/or a conductive polymer. These structures are suitable for preventing or inhibiting the charging of the surface protective film. The prevention or suppression of electrification of the surface protective film is suitable for the ease of operation such as ensuring the adhesion of the surface protective film to the surface to be protected. Furthermore, the prevention or suppression of electrification of the surface protective film is suitable for preventing or suppressing minute foreign matter such as dust from entering between the surface protective film and the surface to be protected to which it is bonded.

The surface protective film is preferably a vacuum pressure forming laminating film. The so-called vacuum forming laminating film refers to a type of film that is adhered to the surface of the adherend through the method of vacuum forming. Vacuum pressure forming is a method in which a film is heated while softening it so that it adheres to the surface of an adherend. This surface protective film is a vacuum pressure-formed laminating film. The structure is suitable for: This surface protective film can properly follow the surface of non-flat parts such as curved parts or flexed parts in the surface of the adherend to be protected. Shape, one side is used to fit the surface to be protected.

According to a second aspect of the present invention, an optical member is provided. This optical member includes the above-mentioned surface protective film according to the first aspect of the present invention. According to the present optical member, the same technical effects as those described above with respect to the first aspect of the present invention can be enjoyed with respect to the surface protective film thereof.

FIG. 1 is a partial cross-sectional view of a film 10 according to an embodiment of the surface protective film of the present invention. The film 10 has a laminated structure including a base film 11 and an adhesive layer 12 . The film 10 can be used, for example, by being bonded to the surface of the optical member in order to protect the surface of the optical member during the manufacturing process of various optical members such as a transparent cover member for a display incorporated into the display, or during the inspection step, transportation process, etc. In addition, in this embodiment, the film 10 is a type of film that is bonded to an adherend while being heated, and is preferably a vacuum pressure forming bonding type film.

The base film 11 in the film 10 is a translucent film-like base material and is an element that functions as a support in the film 10 . The base film 11 is, for example, a plastic film. Examples of the constituent materials of the plastic film include: polyester, polyolefin, polyamide, polyimide, polycarbonate, polyacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and polyvinyl alcohol. Fluoroethylene. Examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Examples of the polyolefin include polyethylene, polypropylene, polybutene, polymethylpentene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-(methyl ) acrylate copolymer, and ethylene-vinyl alcohol copolymer. Examples of polyamides include nylon 6, nylon 6,6, and partially aromatic polyamides. The base film 11 may include one kind of material, or may include two or more materials. The base film 11 may have a single-layer structure or a multi-layer structure.

When the base film 11 includes a plastic film, it may be a biaxially stretched film, a uniaxially stretched film, or a non-stretched film. When the base film 11 is a stretched film, the stretching ratio is, for example, 1.2 to 10. The stretch ratio of the base film 11 in the MD direction and the stretch ratio in the TD direction may be the same or different.

The thickness of the base film 11 is preferably 10 μm or more, more preferably 15 μm or more, and more preferably 15 μm or more, from the viewpoint of ensuring the strength for the base film 11 to function as a support in the film 10 25 μm or more. Moreover, from the viewpoint of achieving appropriate flexibility in the film 10, the thickness of the base film 11 is preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, further preferably 75 μm or less. .

The base film 11 may also have antistatic properties. For example, the base film 11 may be made of a resin material in which antistatic components are dispersed, or may have a laminated structure including an antistatic layer. The antistatic layer may be provided on the surface of the adhesive layer 12 side of the above-mentioned plastic film used for the base film 11 , or may be provided on the surface opposite to the adhesive layer 12 .

When the base film 11 has a laminated structure including an antistatic layer, the antistatic layer contains an antistatic component. The antistatic layer may contain one antistatic component, or may contain two or more antistatic components. In addition, the antistatic layer may contain a binder component if necessary.

Examples of the antistatic component include cationic antistatic agents, anionic antistatic agents, amphoteric antistatic agents, and nonionic antistatic agents.

Examples of the cationic antistatic agent include antistatic agents having a cationic functional group such as a functional group in the form of a quaternary ammonium salt, a functional group in the form of a pyridinium salt, and a primary, secondary or tertiary amino group. Examples of the antistatic agent having a quaternary ammonium salt as a cationic functional group, that is, a quaternary ammonium group include alkyl trimethyl ammonium salt, acyl amide propyl trimethyl ammonium methyl sulfate, and alkyl trimethyl ammonium methyl sulfate. Acrylic copolymers with quaternary ammonium groups such as benzyl methyl ammonium salt, acyl choline chloride, and polydimethylamine ethyl methacrylate, polyethylene benzyl trimethyl ammonium chloride, etc. have quaternary ammonium groups. Styrene copolymers with quaternary ammonium groups, and diallylamine copolymers with quaternary ammonium groups such as polydiallyldimethylammonium chloride.

Examples of the anionic antistatic agent include alkane sulfonates, alkyl benzene sulfonates, alkyl sulfate ester salts, alkyl ethoxy sulfate ester salts, alkyl phosphate ester salts, and sulfonate-containing benzene. Ethylene copolymer.

Examples of the amphoteric antistatic agent include alkyl betaine, alkyl imidazolium betaine, and carbonyl betaine graft copolymer.

Examples of nonionic antistatic agents include fatty acid hydroxyalkylamide, di(2-hydroxyethyl)alkylamine, polyoxyethylene alkylamine, fatty acid glyceryl ester, and polyoxyethylene glycol fatty acid ester. , sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyethylene glycol, polyoxyethylene diamine, and methoxypolyethylene glycol Alcohol (meth)acrylate, etc.

Examples of the antistatic component include conductive polymers. Examples of the conductive polymer include polyaniline conductive polymers such as polyaniline sulfonic acid and polythiophene conductive polymers such as polyaniline-doped polythiophenes.

The weight average molecular weight (Mw) of the conductive polymer used as the antistatic component is preferably 1×10 ³ or more, more preferably 5×10 ³ or more. The weight average molecular weight (Mw) of the conductive polymer means a standard polystyrene-converted value measured by gel permeation chromatography (GPC).

When polyaniline sulfonic acid is used as the conductive polymer, the weight average molecular weight (Mw) of the polyaniline sulfonic acid is preferably 5×10 ⁵ or less, more preferably 3×10 ⁵ or less. As a commercial product of polyaniline sulfonic acid, the trade name "aqua-PASS" manufactured by Mitsubishi Rayon Co., Ltd. is mentioned, for example.

Examples of the polythiophenes include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly (3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-decylthiophene) Octalkylthiophene), 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-ethoxy Thiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptoxythiophene), poly(3-octoxythiophene), poly(3-decyloxy Thiophene), 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-dihexyloxy Thiophene), poly(3,4-diheptoxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-20 dialkoxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene) , poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene) ), poly(3-methyl-4-carboxyethylthiophene), and poly(3-methyl-4-carboxybutylthiophene). From the viewpoint that the base film 11 or the antistatic layer exhibits high conductivity and thereby exhibits good antistatic properties, the polythiophenes are preferably poly(3,4-ethylenedioxy). Thiophene).

The above-mentioned polyanionics are polymers having anionic structural units and function as dopants for polythiophenes. Examples of the polyanions include polystyrene sulfonic acid, polyethylene sulfonic acid, polyaromatic acid, polypropylene sulfonic acid, polymethacryl sulfonic acid, and poly(2-acrylamide-2-methylpropane). sulfonic acid), polyisoprene sulfonic acid, polysulfoethyl methacrylate, poly(4-sulfobutyl methacrylate), polymethallyloxybenzenesulfonic acid, polyethylene carboxylic acid, Polystyrene carboxylic acid, polyaromatic carboxylic acid, polypropylene carboxylic acid, polymethacrylic carboxylic acid, poly(2-acrylamide-2-methylpropanecarboxylic acid), polyisoprene carboxylic acid, polyacrylic acid , and polysulfonated phenylacetylene. From the viewpoint that the polythiophenes exhibit high electrical conductivity, polystyrene sulfonic acid is preferred as the polyanions.

From the viewpoint of the base film 11 or the antistatic layer exhibiting good antistatic properties, the base film 11 or the antistatic layer preferably contains the above-mentioned antistatic agent having a quaternary ammonium group and/or the above-mentioned conductive polymer as an antistatic component. In addition, the conductive polymer as the antistatic component is preferably polyanionic polyphenylene from the viewpoint of exhibiting high conductivity in the base film 11 or the antistatic layer and thus good antistatic properties. Ethylene sulfonic acid-doped polythiophene-based poly(3,4-ethylidenedioxythiophene).

Examples of the binder component in the antistatic layer include polyester resin, acrylic resin, acrylic-urethane resin, acrylic-styrene resin, acrylic-silicone resin, silicone resin, and polysilicone resin. Alkane resin, fluorine resin, polyethylene resin, urethane resin, melamine resin, and epoxy resin.

The antistatic layer or the composition used to form it may also contain lubricants, or leveling agents, cross-linking agents, antioxidants, colorants (pigments, dyes, etc.), fluidity adjusters (thixotropic agents, additives, etc.) as needed. Adhesives, etc.), film-forming aids, catalysts (such as ultraviolet polymerization initiators in compositions containing ultraviolet curable resins) and other additives. As the cross-linking agent, various cross-linking agents such as isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and melamine-based cross-linking agents commonly used for cross-linking resins can be appropriately selected and used.

In this embodiment, the base film 11 has a laminated structure including an antistatic layer, and the antistatic layer or the composition used to form the antistatic layer preferably contains a lubricant. In the antistatic layer, one kind of lubricant can be used, or two or more lubricants can be used.

As the lubricant, fatty acid amide and/or fatty acid ester is preferably used. When fatty amide and/or fatty acid ester are used as the lubricant in the antistatic layer, even if the surface of the antistatic layer is not subjected to a peeling treatment (for example, a silicone-based peeling agent or a long-chain alkyl-based peeling agent is peeled off) When the treatment agent is applied to the surface of the layer and dried), sufficiently high sliding properties are obtained on the surface of the antistatic layer, thereby obtaining high friction resistance in the antistatic layer or the base film 11. By not performing peeling treatment on the exposed surface of the antistatic layer or the base film 11, it is possible to avoid whitening caused by the peeling agent used for the peeling treatment (for example, whitening due to storage under heated and humidified conditions). It is preferable in terms of solvent resistance, and it is also advantageous in terms of solvent resistance of the exposed surface of the antistatic layer or base film 11 .

Examples of the fatty acid amide include laurylamide, palmitamide, stearylamine, behenylamide, hydroxystearamide, oleylamide, erucamide, N-oleylpalmitamide, N-stearyl stearamide, N-stearyl oleyl amide, N-oleyl stearamide, N-stearyl erucamide, hydroxymethyl stearamide, methylene distearamide Ethylidene, ethylbisdecylamide, ethylbislaurylamide, ethylbisstearylamide, ethylbishydroxystearylamide, ethylbisbehenamide, hexaamide Methyl distearylamide, hexamethylene distearylamide, hexamethylene hydroxystearamide, N,N'-distearyl hexamethylene diamide, N,N'-distearyl Ethyldecanediamide, ethylidenebisoleamide, ethylbiserucamide, hexamethylenebisoleamide, N,N'-dioleyl hexamethylenediamine, N,N'-dioleamide Oil-based decanediamide, m-xylylenedimethyl distearamide, m-xylylenedihydroxystearamide, and N,N'-stearyl isophthalamide.

Examples of the fatty acid ester include esters of higher fatty acids and higher alcohols (that is, wax esters). The so-called "higher fatty acids" used to form wax esters refer to carboxylic acids with 8 or more carbon atoms. The higher fatty acid is typically a monocarboxylic acid, and the number of carbon atoms in the higher fatty acid is typically 10 or more, preferably 10 to 40. The so-called "higher alcohols" used to form wax esters mean alcohols with 6 or more carbon atoms. The higher alcohol is typically a monohydric or dihydric alcohol, preferably a monohydric alcohol. The carbon number of the higher alcohol is typically 10 or more, preferably 10 to 40. The antistatic layer composed of such wax ester and the above-mentioned adhesive component is not easy to turn white even if it is stored under high temperature and humid conditions. In order to ensure good appearance quality of the film 10 as a surface protective film provided with the base film 11, it is preferable that the antistatic layer in the base film 11 does not become white easily.

Examples of the wax ester include melisyl cerate, melisyl palmitate, cetyl palmitate, and stearyl stearate.

In addition, as the lubricant in the antistatic layer, natural wax containing the above-mentioned wax ester can also be used. The content ratio of the above-mentioned wax esters in this natural wax (when the natural wax contains two or more wax esters, the total of equal content ratios) is preferably 50 mass on a non-volatile content (NV) basis. % or more, more preferably 65 mass % or more, more preferably 75 mass % or more. Examples of natural waxes include carnauba wax (containing melisyl cereus as a main component), vegetable waxes such as palm wax, and animal waxes such as beeswax and spermaceti. The ratio of melisyl cerate in the carnauba wax is preferably 60 mass% or more, more preferably 70 mass% or more, and more preferably 80 mass% or more.

When wax ester or natural wax is used as the lubricant in the antistatic layer, the melting point of the wax component (wax ester, natural wax) is preferably 50°C or above in order to suppress the whitening of the antistatic layer. More preferably, it is 60°C or higher, more preferably 70°C or higher, still more preferably 75°C or higher. The melting point is preferably 100° C. or lower in order to ensure sufficiently high sliding properties on the exposed surface of the antistatic layer or the base film 11 and to achieve high friction resistance.

Examples of lubricants other than the above include petroleum waxes (paraffin wax, etc.), mineral waxes (montan wax, etc.), higher fatty acids (ceric acid, etc.), neutral fats (palmitic acid triglyceride, etc.), etc. Various waxes. In addition, a lubricant other than wax, such as a silicone-based lubricant or a fluorine-based lubricant, may be used as a lubricant mixed with the wax in the antistatic layer. However, in this embodiment, the antistatic layer is preferred. It contains substantially no silicone lubricant or fluorine lubricant. Furthermore, it is not excluded that silicone-based compounds used for purposes different from the lubricant formulation purpose (for example, expected to function as a defoaming agent in the antistatic layer-forming composition) are blended into the antistatic layer or used to form the lubricant. in its composition.

The proportion of the lubricant in the entire antistatic layer in the base film 11 is preferably 1 mass % or more, and more preferably 5 mass % or more in order to ensure the sliding properties of the antistatic layer surface. In terms of suppressing whitening of the antistatic layer, the above ratio is preferably 50 mass% or less, more preferably 40 mass% or less.

The antistatic layer can be formed, for example, by applying a composition containing an antistatic component and an optional resin component to the base film body and then drying the composition.

The surface of the base film 11 on the adhesive layer 12 side may also be subjected to surface treatment to improve the adhesion with the adhesive layer 12 . Examples of such surface treatment include physical treatments such as corona treatment and plasma treatment, and chemical treatments such as primer treatments.

The storage elastic modulus (first storage elastic modulus) of the base film 11 at 130°C is 700 MPa or less, preferably 500 MPa or less, more preferably 300 MPa or less, more preferably 200 MPa or less, more preferably 100 MPa or less, more preferably 80 MPa or less. The storage elastic modulus (second storage elastic modulus) of the base film 11 at 30°C is 1000 MPa or more, preferably 1500 MPa or more, more preferably 2000 MPa or more, more preferably 2500 MPa or more, more preferably 2700 MPa or more, preferably 2800 MPa or more. The storage elastic modulus (third storage elastic modulus) of the base film 11 at 80°C is above the first storage elastic modulus and below the second storage elastic modulus, for example, 700 to 1100, preferably 700 to 1000. MPa. The storage elastic modulus of the base film 11 can be adjusted by adjusting the composition of the plastic film constituent material contained in the base film 11 or adjusting the stretching ratio of the base film 11 . In addition, the storage elastic modulus of the membrane body can be determined based on dynamic viscoelasticity measurement using a dynamic viscoelasticity measuring device (trade name "RSΑ-G2", manufactured by TA INSTRUMENTS). In this measurement, the size of the test piece to be measured is 5 mm in width x 30 mm in length, the initial distance between the chucks for holding the test piece is 10 mm, and the measurement mode is set to tensile. mode, set the measurement temperature range to 25 to 170°C, the frequency to 1 Hz, and the temperature rise rate to 5°C/min.

As a material constituting the base film 11, in terms of easily achieving better storage elastic modulus (first storage elastic modulus, second storage elastic modulus, third storage elastic modulus), etc., it is preferable to include polyethylene. ester. As the above-mentioned polyester, a polyester containing as a main component a polyester obtained by polycondensing a dicarboxylic acid and a diol is typically used.

Examples of the dicarboxylic acid constituting the polyester include phthalic acid, isophthalic acid, terephthalic acid, 2-methylterephthalic acid, 5-sulfoisophthalic acid, 4,4 '-Diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylketonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4 , 4'-diphenyl dicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid and other aromatic Dicarboxylic acid; 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids; malonic acid, butanedioic acid Acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanoic acid and other aliphatic dicarboxylic acids; maleic acid, maleic anhydride, fumaric acid and other unsaturated acids Dicarboxylic acids; their derivatives (such as terephthalic acid and other lower alkyl esters of the above-mentioned dicarboxylic acids), etc. These can be used individually by 1 type, or in combination of 2 or more types.

As the dicarboxylic acid constituting the above-mentioned polyester, the base film 11 can easily achieve a better storage elastic modulus (the first storage elastic modulus, the second storage elastic modulus, and the third storage elastic modulus). Aromatic dicarboxylic acids are preferred. Among these, preferred dicarboxylic acids include terephthalic acid and isophthalic acid. For example, it is preferable that 50% by weight or more (for example, 80% by weight or more, typically 95% by weight or more) of the dicarboxylic acids constituting the polyester be terephthalic acid, isophthalic acid, or a combination thereof. . The above-mentioned dicarboxylic acid may also contain substantially only terephthalic acid, substantially only isophthalic acid, or substantially only terephthalic acid and isophthalic acid.

When the material constituting the base film 11 is polyester using both terephthalic acid and isophthalic acid, the ratio of terephthalic acid to isophthalic acid (terephthalic acid/isophthalic acid) does not matter. It is particularly limited. For example, it can be suitably selected from the range of 99/1 to 50/50, preferably 95/5 to 60/40, more preferably 90/10 to 70/30, and particularly preferably 87/13 to 80/20. select.

Examples of glycols constituting the polyester include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propylene glycol, 1,5-pentanediol, and neopentyl glycol. , 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, polyoxytetramethylene glycol and other aliphatic diols; 1,2-cyclohexanediol, 1 , 4-cyclohexanediol, 1,1-cyclohexanedihydroxymethyl, 1,4-cyclohexanedihydroxymethyl and other alicyclic glycols, benzenedimethanol, 4,4'-dihydroxy Aromatic diols such as biphenyl, 2,2-bis(4'-hydroxyphenyl)propane, bis(4-hydroxyphenyl)terine, etc. These can be used individually by 1 type or in combination of 2 or more types.

As the glycol constituting the above-mentioned polyester, the base film 11 can easily achieve a better storage elastic modulus (the first storage elastic modulus, the second storage elastic modulus, and the third storage elastic modulus). Preferred are aliphatic diols. Among these, preferred glycols include ethylene glycol and diethylene glycol. For example, it is preferable that 50% by weight or more (for example, 80% by weight or more, typically 95% by weight or more) of the glycols constituting the polyester be ethylene glycol, diethylene glycol, or a combination thereof. The above-mentioned glycol may also include substantially only ethylene glycol, substantially only diethylene glycol, or substantially only ethylene glycol and diethylene glycol.

When the material constituting the base film 11 is polyester using both ethylene glycol and diethylene glycol, the ratio of ethylene glycol and diethylene glycol (ethylene glycol/diethylene glycol) is not particularly limited. For example, it can be appropriately selected from the range of 99.9/0.1 to 80/20, preferably 99.5/0.5 to 85/15, more preferably 99/1 to 90/10, and particularly preferably 98/2 to 95/5.

The base film 11 is preferably a stretched film in terms of easily achieving better storage elastic modulus (first storage elastic modulus, second storage elastic modulus, third storage elastic modulus). When the base film 11 is a stretched film, it may be a biaxially stretched film or a uniaxially stretched film. When the base film 11 is a stretched film, its stretching ratio can easily achieve better storage elastic modulus (first storage elastic modulus, second storage elastic modulus, third storage elastic modulus), etc. , for example, 1.1 to 3, preferably 1.2 to 2, more preferably 1.3 to 1.8, particularly preferably 1.4 to 1.6. The stretch ratio of the base film 11 in the MD direction and the stretch ratio in the TD direction may be the same or different.

The adhesive layer 12 of the film 10 or the adhesive composition used to form it has an adhesive and is light-transmissive. The adhesive layer 12 includes, for example, at least one selected from the group consisting of an acrylic polymer as an acrylic adhesive, a polyurethane as a urethane adhesive, and a silicone adhesive. As an adhesive. From the viewpoint of achieving both the required degree of adhesion and high transparency required for the adhesive layer of the surface protective film, an acrylic polymer is preferably used as the adhesive in the adhesive layer 12 . In addition, the adhesive layer 12 has an adhesive surface 12a capable of sticking to an adherend.

When the adhesive layer 12 contains an acrylic polymer as an acrylic adhesive, it is preferable that the acrylic polymer contains an alkyl (meth)acrylate derived from an alkyl group having a carbon number of, for example, 4 to 12. The monomer units of the base ester are the most numerous primary monomer units in terms of weight ratio. Hereinafter, "(meth)acrylate" means "acrylate" and/or "methacrylate".

As the (meth)acrylic acid alkyl ester used to form the monomer unit of the above-mentioned acrylic polymer, that is, the (meth)acrylic acid alkyl ester contained in the monomer component used to form the above-mentioned acrylic polymer, for example, Examples: (butyl methacrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, amyl (meth)acrylate, (meth)acrylic acid Isoamyl ester, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ( Nonyl methacrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and (meth)acrylic acid Lauryl ester. As the (meth)acrylic acid alkyl ester used for the acrylic polymer, one (meth)acrylic acid alkyl ester can be used, or two or more (meth)acrylic acid alkyl esters can be used. In this embodiment, as the (meth)acrylic acid alkyl ester used in the acrylic polymer, a third compound selected from the group consisting of butyl (meth)acrylate, isobutyl (meth)acrylate, and (meth)acrylic acid is used. At least one of the group consisting of butyl ester and 2-ethylhexyl (meth)acrylate. The ratio of monomer units derived from alkyl (meth)acrylate in the acrylic polymer is, for example, 50 to 99.9 mass%, preferably 70 to 99.9 mass%, and more preferably 80 to 99.5 mass%.

The above-mentioned acrylic polymer may also contain monomer units derived from hydroxyl-containing monomers. Hydroxyl-containing monomers are monomers that have at least one hydroxyl group in the monomer unit. When the acrylic polymer in the adhesive layer 12 contains hydroxyl-containing monomer units, the adhesive layer 12 can easily obtain adhesiveness or appropriate cohesive force. When the adhesive composition for forming the adhesive layer 12 contains an acrylic polymer containing a hydroxyl-containing monomer unit and, for example, an isocyanate-based cross-linking agent, the hydroxyl group (containing an active hydrogen functional group) of the hydroxyl-containing monomer unit can Functions as a cross-linking point.

Examples of the hydroxyl-containing monomer used to form the monomer unit of the acrylic polymer include: (meth)acrylic acid 2 -Hydroxyethyl ester, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, ( 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and [4-(hydroxymethyl) base) cyclohexyl] methyl acrylate. As the hydroxyl-containing monomer used in the acrylic polymer, one hydroxyl-containing monomer may be used, or two or more hydroxyl-containing monomers may be used. In this embodiment, it is preferable to use 2-hydroxyethyl (meth)acrylate as the hydroxyl-containing monomer used for the acrylic polymer. From the viewpoint of achieving adhesiveness or appropriate cohesive force in the formed adhesive layer 12, the ratio of monomer units derived from hydroxyl-containing monomers in the acrylic polymer is preferably, for example, 0.1 to 30% by mass. It is 0.5~20 mass%.

The acrylic polymer contained in the adhesive layer 12 may also contain monomer units derived from carboxyl group-containing monomers. Carboxyl-containing monomers are monomers with at least one carboxyl group in the monomer unit. When the acrylic polymer in the adhesive layer 12 contains carboxyl group-containing monomer units, it is easy to obtain good bonding reliability in the adhesive layer 12 . When the adhesive composition for forming the adhesive layer 12 contains an acrylic polymer containing a carboxyl group-containing monomer unit and an isocyanate-based crosslinking agent, for example, the carboxyl group (containing an active hydrogen functional group) of the carboxyl group-containing monomer unit can Functions as a cross-linking point.

Examples of the carboxyl group-containing monomer used to constitute the monomer unit of the acrylic polymer include: (meth)acrylic acid, Iconic acid, maleic acid, and β-carboxyethyl acrylate. As the carboxyl group-containing monomer used in the acrylic polymer, one type of carboxyl group-containing monomer can be used, or two or more types of carboxyl group-containing monomers can be used. In this embodiment, acrylic acid is preferably used as the carboxyl group-containing monomer used for the acrylic polymer. From the viewpoint of ensuring good adhesion reliability in the formed adhesive layer 12, the ratio of monomer units derived from carboxyl group-containing monomers in the acrylic polymer is, for example, 0.1 to 20% by mass, preferably 0.1 to 20% by mass. 0.5～15% by mass.

The acrylic polymer contained in the adhesive layer 12 may also contain monomer units derived from vinyl ester monomers. Vinyl ester monomer system is a monomer having at least one vinyl ester group in the monomer unit. When the acrylic polymer in the adhesive layer 12 contains vinyl ester monomer units, it is easy to obtain good cohesion in the adhesive layer 12 .

Examples of the vinyl ester monomer used to form the monomer unit of the acrylic polymer include vinyl acetate, Vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, vinyl benzoate. As the vinyl ester monomer used for the acrylic polymer, one vinyl ester monomer may be used, or two or more vinyl ester monomers may be used. In this embodiment, vinyl acetate is preferably used as the vinyl ester monomer used for the acrylic polymer. From the viewpoint of ensuring good cohesion of the adhesive layer 12 formed, the ratio of monomer units derived from vinyl ester monomers in the acrylic polymer is, for example, 10 to 60 mass %, preferably 20 ~50% by mass.

The acrylic polymer contained in the adhesive layer 12 may also contain monomer units derived from other monomers. Examples of other monomers include monomers containing active hydrogen-containing functional groups, nitrogen atom-containing monomers, epoxy group-containing monomers, Alkoxy monomers, cyano group-containing monomers, styrenic monomers, isocyanate group-containing monomers, (meth)acrylates with heterocyclic rings, halogen atom-containing monomers, alkoxysilane group-containing monomers Polyfunctional monomers such as monomers containing siloxane bonds, (meth)acrylates containing alicyclic hydrocarbon groups, (meth)acrylates containing aromatic hydrocarbon groups, and multifunctional (meth)acrylates.

Examples of the nitrogen atom-containing monomer include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, 2-vinylpyridine, N-vinylpiperidone, and 5-ethylene. Pyrimidine, N-vinylpiperidine, 2-vinylpyridine, N-vinylpyrrole, N-vinylimidazole, 4-vinylethazole, N-vinylpyridine, N-vinylcaprolactone Amine, N-(meth)acrylamide, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N- Hydroxymethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(methyl) Acrylamide, (meth)acrylic acid aminoethyl ester, (meth)acrylic acid N,N-dimethylaminoethyl ester, (meth)acrylic acid tert-butylaminoethyl ester, etc.

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

Examples of the alkoxy group-containing monomer include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and the like.

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

Examples of the styrene-based monomer include styrene, substituted styrene (α-methylstyrene, etc.), vinyl toluene, and the like.

Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate.

Examples of the (meth)acrylate having a heterocyclic ring include tetrahydrofuran methyl (meth)acrylate.

Examples of the halogen atom-containing monomer include vinyl chloride, vinylidene chloride, and the like.

Examples of the alkoxysilyl group-containing monomer include: 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc.

Examples of the monomer having a siloxane bond include silicone (meth)acrylate.

Examples of the alicyclic hydrocarbon group-containing (meth)acrylate include: (meth)cyclopentyl acrylate, (meth)cyclohexyl acrylate, (meth)isoacrylate, (meth)acrylate Dicyclopentyl acrylate, adamantyl (meth)acrylate, etc.

Examples of the aromatic hydrocarbon group-containing (meth)acrylate include: (meth)aryl acrylate (for example, phenyl (meth)acrylate), (meth)aryloxyalkyl acrylate (for example) (Phenoxyethyl acrylate), aralkyl (meth)acrylate (such as benzyl (meth)acrylate), etc.

Examples of the polyfunctional monomer include hexylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol Tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.

The other monomer raw materials in the technology disclosed here can be used alone or in combination of two or more for the purpose of adjusting the Tg of the acrylic polymer or improving the cohesive force.

The weight average molecular weight (Mw) of the acrylic polymer contained in the adhesive layer 12 is, for example, 100,000 to 3,000,000, preferably 200,000 to 2,000,000, more preferably 300,000 to 1.5 million, more preferably 400,000. ~1 million. The weight average molecular weight (Mw) of the acrylic polymer means a standard polystyrene-converted value measured by gel permeation chromatography (GPC).

The glass transition temperature (Tg) of the acrylic polymer contained in the adhesive layer 12 is, for example, 0°C or lower, preferably -10°C or lower, more preferably -30°C or lower, more preferably -50°C or lower. The glass transition temperature of an acrylic polymer can be measured using a dynamic viscoelastic device or calculated using the FOX formula.

The above-mentioned urethane polymer used as the adhesive for the adhesive layer 12 is a polymer having multiple urethane bonds in the molecular chain, and is a polyol such as polymer ethylene glycol or low molecular weight ethylene glycol. , diisocyanate and other multifunctional isocyanates, and polymers containing active hydrogen compounds used as needed. In this embodiment, the urethane polymer preferably has an active hydrogen-containing functional group such as a hydroxyl group or a carboxyl group that can react with an isocyanate cross-linking agent on the main chain or side chain.

The adhesive such as acrylic polymer or urethane polymer in the adhesive layer 12 can also be cross-linked by a cross-linking agent. The gel fraction of the adhesive layer 12 can be adjusted by cross-linking the adhesive by the cross-linking agent. Examples of such cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, melamine-based cross-linking agents, and metal chelate-based cross-linking agents. The adhesive composition used to form the adhesive layer 12 may contain one cross-linking agent, or may contain two or more cross-linking agents. In this embodiment, it is preferable to use an isocyanate cross-linking agent and/or an epoxy cross-linking agent.

Examples of isocyanate-based crosslinking agents include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates. Examples of aliphatic isocyanates include trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and dimer acid diisocyanate. Examples of alicyclic isocyanates include cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophorone diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane. Examples of aromatic isocyanates include 2,4-methylphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylenediisocyanate. Examples of the isocyanate cross-linking agent include trimethylolpropane adduct of tolylene diisocyanate (trade name "Coronate L", manufactured by Tosot Co., Ltd.) or hexamethylene diisocyanate. Coronate HX (trade name: "Coronate HX", manufactured by Tosot Co., Ltd.).

Examples of the epoxy cross-linking agent (polyfunctional epoxy compound) include: N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3- Bis(N,N-diglycidylaminemethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether.

When the adhesive composition for forming the adhesive layer 12 contains a cross-linking agent, from the viewpoint of realizing sufficient adhesion reliability to the adherend of the formed adhesive layer 12, relative to the composition 100 parts by mass of the adhesive in the adhesive is, for example, 0.1 to 20 parts by mass, preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass.

The adhesive layer 12 or the adhesive composition used to form it may also contain cross-linking accelerators, or adhesion-imparting resins, anti-aging agents, fillers, antioxidants, plasticizers, softeners, surfactants, Various additives such as antistatic agents.

The thickness of the adhesive layer 12 is preferably 1 μm or more, more preferably 5 μm or more, more preferably 10 μm or more, and more preferably 15 μm, from the viewpoint of achieving sufficient adhesion to the adherend. above. In addition, from the viewpoint of ease of formation, the thickness of the adhesive layer 12 is preferably 200 μm or less, more preferably 100 μm or less, more preferably 50 μm or less, and more preferably 30 μm or less.

In addition, the haze in the thickness direction of the film 10 is preferably 5% or less, more preferably 3% or less, and more preferably 1.5% or less. The haze is set to the value measured in accordance with JIS K 7136.

The film 10 having the above-mentioned laminated structure may also be provided with a release film or a release liner so as to cover the adhesive surface 12 a of the adhesive layer 12 . The isolation film is an element used to protect the adhesive layer 12 of the film 10 from being exposed, and is peeled off from the film 10 when the film 10 is attached to an adherend. Examples of the separator include a base material having a release-treated layer, a low-adhesion base material containing a fluoropolymer, and a low-adhesion base material containing a non-polar polymer. The surface of the isolation film can also be subjected to release treatment, antifouling treatment, or antistatic treatment. The thickness of the isolation film is, for example, 5 to 200 μm. Specifically, the film 10 may be in a sheet-like form accompanied by a release film covering the adhesive surface 12a of the adhesive layer 12, or may be in a sheet-like form without being accompanied by a release film and the base film 11 and the adhesive layer 12 of the film 10 may be alternately The arrangement is rolled into a drum shape.

The film 10 having the above structure can be produced in the following manner, for example. First, a composition for forming the adhesive layer 12 is prepared. The composition contains the specific ingredients and solvents described above with respect to the adhesive layer 12 . Examples of the solvent include esters such as ethyl acetate, aromatic hydrocarbons such as toluene, aliphatic hydrocarbons such as n-hexane, and alicyclic hydrocarbons such as cyclohexane. Next, the adhesive composition for forming the adhesive layer 12 is coated on the base film 11 to form an adhesive composition layer, and the composition layer is dried and solidified to form the adhesive layer 12 . Alternatively, the film 10 can also be produced by forming the adhesive layer 12 on the isolation film and then bonding the adhesive layer 12 to the base film 11 .

In the film 10 as the surface protective film having the above-described structure, the base film 11 has a storage elastic modulus at 130° C. of 700 MPa or less, preferably 500 MPa or less, and more preferably 300 MPa, as described above. or less, more preferably 200 MPa or less, more preferably 100 MPa or less, more preferably 80 MPa or less. This configuration is suitable for a surface to be protected by an adherend including a non-flat part such as a curved part or a deflection part, so that the film 10 can follow the non-flat part in a state that is sufficiently softened by, for example, heating to about 100° C. or above. According to the surface shape, one side is attached.

In addition, as mentioned above, the base film 11 of the film 10 has a storage elastic modulus at 30°C of 1000 MPa or more, preferably 1500 MPa or more, more preferably 2000 MPa or more, more preferably 2500 MPa or more, more preferably 2700 MPa or more, preferably 2800 MPa or more. This configuration is suitable for a surface to be protected by an adherend that includes uneven portions such as curved portions or flexed portions. The film 10 side is sufficiently softened, for example, by heating to about 100° C. or above to follow the surface shape of the uneven portion. , after one side is bonded to the surface to be protected, and the film 10 maintains the shape following the non-flat surface shape while the film is cooled to about room temperature.

As described above, the film 10 is suitable for following the non-flat surface shape in the surface to be protected while being in a state of being sufficiently softened by heating to about 100°C or above, for example, while being adhered to the surface to be protected; and is suitable for: After this bonding, the shape can be maintained to follow the non-flat surface shape under temperature conditions around room temperature. This type of film 10 is suitable for covering and protecting a surface to be protected that has a non-flat portion such as a curved portion or a flexed portion.

As mentioned above, the base film 11 of the film 10 preferably has a laminated structure including an antistatic layer. As mentioned above, the antistatic layer preferably contains an antistatic agent having a quaternary ammonium group and/or a conductive polymer. These structures are suitable for preventing or suppressing charging of the film 10 . The prevention or suppression of electrification of the film 10 is suitable for ensuring ease of operation such as adhering the film 10 to the surface to be protected. In addition, the prevention or suppression of charging of the film 10 is suitable for preventing or suppressing the entry of tiny foreign matter such as dust into the space between the film 10 and the surface to be protected to which it is bonded.

As mentioned above, the film 10 is preferably a vacuum pressure forming lamination type film. The film 10 is a vacuum pressure-formed lamination type film. The structure of the film 10 is suitable for the film 10 to properly follow the surface shape of non-flat areas such as bends or flexures in the surface of the adherend to be protected. Used in accordance with the protection object.

FIG. 2 is a partial cross-sectional view of an optical member 20 with a film 10 according to another embodiment of the present invention.

The optical member 20 is, for example, a transparent cover member for a display incorporated into the display. Examples of displays include liquid crystal displays and organic electroluminescent displays for smartphones and televisions. Furthermore, the optical member 20 has a surface 21 to be protected by a surface protective film. The surface 21 has a curved portion 21a and a deflection portion 21b. The optical member 20 includes, for example, a transparent resin-based material or a glass-based material.

For the surface 21 of such an optical member 20, the above-mentioned film 10 as a surface protective film is bonded to its adhesive layer (not shown in FIG. 2) side. The film 10 is adhered to all parts of the curved portion 21a and the deflected portion 21b of the surface 21.

According to the optical member 20 provided with the film 10 , the same technical effects as those described above with respect to the film 10 can be enjoyed with respect to the film 10 . That is, in the optical member 20 provided with the film 10, the film 10 is preferable in terms of covering and protecting the surface 21 (surface to be protected) having non-flat portions such as the curved portion 21a or the flexed portion 21b. Example

[Preparation of base film F ₁ ] Using a stretching device equipped with a specific heating roller group and a tenter, it has an isophthalic acid unit (7 mol%) and a terephthalic acid unit (44 mol%). , polyethylene terephthalate (PET) film (thickness 100 μm, weight average molecular weight (Mw)) as raw material film for ethylene glycol unit (48 mol%) and diethylene glycol unit (1 mol%) 72000, glass transition temperature 75℃) to produce biaxially stretched film. First, the PET film was stretched in the so-called MD direction at a stretching ratio of 1.6 times while passing through a group of heated rollers at 85°C, thereby producing a uniaxially aligned PET film. Next, the PET film is guided into the tenter, stretched in the so-called TD direction at a stretching ratio of 1.6 times in the heating zone at 100°C, and then carried out in the heat treatment zone at 200°C in the tenter. Heat fixation to obtain a polyester film with a thickness of 38 μm. Next, corona treatment is performed on one side of the polyester film. In the above manner, a polyester-based film (base film F ₁ ) having a corona-treated surface on one side was produced.

[Preparation of base film F ₂ ] Prepare the following solution (solution for antistatic layer formation): an acrylic antistatic agent (trade name "BONDEIP-PA100") which is an acrylic copolymer containing quaternary ammonium groups in the side chain. Agent", manufactured by Konishi Co., Ltd.), and epoxy resin as a hardener (trade name "BONDEIP-PA100 Hardener") are contained in a mixed solvent of water and isopropyl alcohol at a mass ratio of 100:100. Next, this solution is applied to the corona-treated surface of the above-mentioned base film F ₁ , and then the coating film is dried. This forms an antistatic layer with a thickness of 100 nm on the surface of the polyester film. In the above manner, a polyester-based film (base film F ₂ ) having an antistatic layer (thickness: 100 nm) on one side was produced.

[Preparation of base film F ₃ ] Using a stretching device equipped with a specific heating roller group and a tenter, the PET film (thickness 100 μm, weight average molecular weight (Mw) 72000, glass transition temperature 75°C) as the raw material film ) to produce biaxially stretched film. First, the PET film was stretched in the so-called MD direction at a stretching ratio of 1.4 times while passing through a group of heated rollers at 85°C, thereby producing a uniaxially aligned PET film. Next, the film is guided into the tenter, stretched in the so-called TD direction at a stretching ratio of 1.4 times in a heating zone of 100°C, and then heated in a heat treatment zone of 200°C in the tenter. Fixed to obtain a polyester film with a thickness of 50 μm. Next, corona treatment is performed on one side of the polyester film. On the other hand, a dispersion _S1 containing 25% by mass of a saturated copolymerized polyester resin as a binder (trade name "VYLONAL MD-1480", manufactured by Toyobo Co., Ltd.) and a water dispersion of carnauba wax as a lubricant were prepared. Liquid S ₂ , aqueous solution S ₃ (trade name) containing 0.5 mass % of poly(3,4-ethylenedioxythiophene) and 0.8 mass % of polystyrene sulfonate (number average molecular weight: 150,000) as a conductive polymer "Baytron P", manufactured by HCStark Co., Ltd.), and solution S ₄ of melamine-based cross-linking agent (trade name "Nikaresin S-176", manufactured by Nippon Carbide Industry Co., Ltd.). Then, 100 parts by mass of the above-mentioned dispersion S ₁ in terms of solid content and 30 parts by mass of the above-mentioned aqueous dispersion S in terms of solid content were added to a mixed solvent with a volume ratio of water and ethanol of 1:3. _2. Mix the above-mentioned aqueous solution S ₃ which is 50 parts by mass in terms of solid content and ₁₀ parts by mass in terms of solid content and stir for about 20 minutes. Thereby, a coating material with a non-volatile component (NV) concentration of approximately 0.15% by mass was prepared. The coating material was applied to the corona-treated surface of the biaxially stretched polyester film with a stretching ratio of 1.4 times, and then the coating film was dried. Thereby, an antistatic layer with a thickness of 15 nm was formed on the surface of the polyester film. In the above manner, a polyester film (base film F ₃ ) having an antistatic layer (thickness: 15 nm) on one side was produced.

[Preparation of Base Film F ₄ ] Dispersion S ₁ (trade name "VYLONAL MD-1480", manufactured by Toyobo Co., Ltd.) containing 25% by mass of saturated copolymer polyester resin as a binder and a conductive polymer were prepared Solution S ₅ of polyaniline sulfonic acid (trade name "aquaPASS", weight average molecular weight 40,000, manufactured by Mitsubishi Rayon Co., Ltd.), hexamethylene diisocyanate blocked with diisopropylamine as a cross-linking agent The solution of isocyanurate body S ₆ and the solution of oleamide as lubricant S ₇ . Then, 100 parts by mass of the above-mentioned dispersion S ₁ in terms of solid content, 75 parts by mass of the above-mentioned solution S ₅ in terms of solid content were added to a mixed solvent with a volume ratio of water and ethanol of 1:3. The above-mentioned solution S ₆ , which is 10 parts by mass in terms of solid content, and the above-mentioned solution S ₇ , which is 30 parts by mass in terms of solid content, are stirred for about 20 minutes and mixed. Thereby, a coating material with a non-volatile component (NV) concentration of approximately 0.4% by mass was prepared. The coating material was applied to the corona-treated surface of the biaxially stretched polyester film with a stretching ratio of 1.4 times, and then the coating film was dried. Thus, an antistatic layer with a thickness of 45 nm was formed on the surface of the polyester film. In the above manner, a polyester film (base film F ₄ ) having an antistatic layer (thickness 45 nm) on one side was produced.

[Preparation of base film F ₅ ] Crystalline homopolypropylene (trade name "F-704NP", resin density 0.900, manufactured by Prime Polymer Co., Ltd.) 40 was made by the T-die method at a junction temperature of 220°C. 40 parts by mass of atactic polypropylene (trade name "F-744NP", resin density 0.900, manufactured by Prime Polymer Co., Ltd.), and ethylene-propylene copolymer (trade name "Tafmer P0180", manufactured by Mitsui Chemicals Co., Ltd. (Manufacture) 20 parts by mass to form a film with a thickness of 40 μm. Next, corona treatment is performed on one side of the obtained film. In the above manner, a polyolefin-based film (base film F ₅ ) with a thickness of 40 μm was produced.

[Preparation of acrylic adhesive composition A ₁ ] In a flask (reaction vessel) equipped with a reflux cooler, a nitrogen introduction pipe, a stirrer, and a thermometer, 96.2 parts by mass of 2-ethylhexyl acrylate, acrylic acid A mixture of 3.8 parts by mass of hydroxyethyl ester, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 150 parts by mass of ethyl acetate was stirred stably under a nitrogen atmosphere at 60°C. Reaction takes 6 hours. Thereby, a solution containing an acrylic polymer at a concentration of 40% by mass (acrylic polymer solution) was obtained. The weight average molecular weight of the acrylic polymer is 540,000. Then, after diluting the acrylic polymer solution with ethyl acetate so that the acrylic polymer concentration becomes 25% by mass, 400 parts by mass (100 parts by weight of solid content) of the acrylic polymer solution was added with solid matter. The ingredient amount is 4 parts by mass of a cross-linking agent (trade name "Coronate L", an ethyl acetate solution with a solid content concentration of 75% by mass, which is a trimethylolpropane adduct of tolylene diisocyanate, Dong (manufactured by Shuttle Co., Ltd.), 0.02 parts by mass of dioctyltin dilaurate (trade name "EMBILIZER OL-1", produced by Tokyo Fine Chemical Co., Ltd.) as a cross-linking catalyst in terms of solid content, and 3 parts by mass of acetylacetone as a cross-linking retardant, and these were stirred and mixed. Thereby, an acrylic adhesive composition (acrylic adhesive composition A ₁ ) was obtained.

[Preparation of Acrylic Adhesive Composition A ₂ ] Isocyanurate of hexamethylene diisocyanate (trade name "Coronate HX"), which is a trifunctional isocyanate compound, was used in an amount of 4 parts by mass in terms of solid content. , manufactured by Tosot Co., Ltd.), as a substitute for the cross-linking agent of the trimethylolpropane adduct of tolylene diisocyanate (trade name "Coronate L", ethyl acetate solution with a solid content concentration of 75% by mass) , manufactured by Tosot Co., Ltd.) as a cross-linking agent, prepare another acrylic adhesive composition (acrylic adhesive composition A ₂ ) in the same manner as the acrylic adhesive composition A ₁ .

[Preparation of Acrylic Adhesive Composition A ₃ ] In a flask (reaction vessel) equipped with a reflux cooler, a nitrogen introduction pipe, a stirrer, and a thermometer, 96 parts by mass of butyl acrylate and 4 parts by mass of acrylic acid were placed. A mixture of 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator and 150 parts by mass of ethyl acetate was reacted at 60° C. for 6 hours while stably stirring in a nitrogen atmosphere. Thereby, a solution containing an acrylic polymer at a concentration of 40% by mass (acrylic polymer solution) was obtained. The weight average molecular weight of the acrylic polymer is 580,000. Then, 100 parts by mass of the solid content of the acrylic polymer and 1,3-bis(N,N-diglycidylaminemethyl)cyclohexane (trade name "Tetrad-C") as an epoxy compound ”, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 3 parts by mass were mixed to obtain an acrylic adhesive composition (acrylic adhesive composition A ₃ ).

[Preparation of acrylic adhesive composition A ₄ ] In a flask (reaction vessel) equipped with a reflux cooler, a nitrogen introduction pipe, a stirrer, and a thermometer, 100 parts of 2-ethylhexyl acrylate and vinyl acetate were placed 80 parts of ester, 5 parts of acrylic acid, 0.3 parts of benzoyl peroxide (BPO, "Nyper (registered trademark) BW" manufactured by NOF Co., Ltd.) as a peroxide polymerization initiator, and 275 parts of toluene The mixture was stirred steadily at room temperature under nitrogen atmosphere for 1 hour. Then, the temperature of the contents of the container was raised to 63°C, and polymerization was performed for 6 hours in a nitrogen gas flow. Then, the temperature of the contents of the container was raised to 80°C, and the reaction was carried out for 6 hours. Thereby, a solution containing an acrylic polymer at a concentration of 40% by mass (acrylic polymer solution) was obtained. The weight average molecular weight of the acrylic polymer is 430,000. Then, 100 parts by mass of the solid content of the acrylic polymer and 1,3-bis(N,N-diglycidylaminemethyl)cyclohexane (trade name "Tetrad-C") as an epoxy compound ”, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 3 parts by mass were mixed to obtain an acrylic adhesive composition (acrylic adhesive composition A ₄ ).

[Preparation of urethane adhesive composition] A urethane-based polymer (trade name "Oribain SH-109", manufactured by TOYOCHEM Co., Ltd.) was diluted to 25% by mass with ethyl acetate to obtain a urethane-based polymer solution. Then, to 400 parts by mass (100 parts by mass of solid content) of this solution, isocycyanurate of hexamethylene diisocyanate (trade name: "Coronate HX", manufactured by Tosot Co., Ltd., which is a trifunctional isocyanate compound ) 10 parts by mass (10 parts by mass of solid content) as a cross-linking agent, and mixed and stirred. In this way, a urethane-based adhesive composition is prepared.

[Example 1] The above-described acrylic adhesive composition A ₁ was applied to the silicone-treated surface of a polyethylene terephthalate release liner (thickness 38 μm) that had been silicone-treated on one side. The adhesive composition layer is formed. Next, the adhesive composition layer was heated at 130° C. for 20 seconds to form an adhesive layer with a thickness of 20 μm. Next, the exposed surface of the adhesive layer is bonded to the surface of the base film F ₂ opposite to the surface where the antistatic layer is formed. In this way, the surface protective film of Example 1 was produced.

[Example 2] A surface protective film of Example 2 was produced in the same manner as the surface protective film of Example 1, except that acrylic adhesive composition A ₂ was used instead of acrylic adhesive composition A ₁ .

[Examples 3 to 5] Except that the base film F ₃ (Example 3), the base film F ₄ (Example 4), or the base film F ₁ (Example 5) was used instead of the base film F ₂ Except for this, each surface protective film of Examples 3 to 5 was produced in the same manner as the surface protective film of Example 1.

[Example 6] The above-described urethane adhesive was applied to the silicone-treated surface of a polyethylene terephthalate release liner (thickness 38 μm) that had been silicone-treated on one side. composition to form an adhesive composition layer. Next, the adhesive composition layer was heated at 130° C. for 20 seconds to form an adhesive layer with a thickness of 10 μm. Next, the exposed surface of the adhesive layer is bonded to the corona-treated surface of the above-mentioned base film _F1 . In this way, the surface protective film of Example 6 was produced.

[Example 7] Corona treatment using acrylic adhesive composition A ₄ instead of acrylic adhesive composition A ₁ to form an adhesive layer with a thickness of 5 μm instead of 20 μm and bonding it to the base material F ₁ Except for this, the surface protective film of Example 7 was produced in the same manner as the surface protective film of Example 1.

[Comparative Example 1] The same procedure as Example 1 was used except that another polyester-based film (base film F ₆ ) (trade name "ASTROLL CE900", thickness 38 μm, manufactured by KOLON Co., Ltd.) was used instead of the base film F ₂ The surface protective film of Comparative Example 1 was produced in the same manner.

[Comparative Example 2] The above-mentioned acrylic adhesive composition A ₃ was applied to the corona-treated surface of the above-mentioned base film F ₅ (thickness 40 μm) as a polyolefin film to form an adhesive composition layer. Next, the adhesive composition layer was heated at 80° C. for 1 minute to form an adhesive layer with a thickness of 5 μm. Next, the silicone-treated side of a polyethylene terephthalate release liner (thickness: 38 μm) that has been silicone-treated on one side was bonded to the exposed surface of the adhesive layer. Secondly, the adhesive layer on the base film _F5 is aged at room temperature for 5 days. Thereby, the surface protective film of Comparative Example 2 was produced.

＜Measurement of storage elastic modulus＞ For each of the base films in the surface protective films of Examples 1 to 7 and Comparative Examples 1 and 2, dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring device (trade name "RSA-G2", manufactured by TA INSTRUMENTS). Measurement was performed to investigate the tensile storage elastic modulus (MPa). In this measurement, the dimensions of the base film test piece to be measured were set to width 5 mm x length 30 mm, the initial distance between the chucks for holding the test piece was set to 10 mm, and the measurement mode was set to In the tensile mode, the measurement temperature range was set to 25 to 170°C, the frequency was set to 1 Hz, and the temperature rise rate was set to 5°C/min. The measurement results at 30°C, 80°C, and 130°C are listed in Table 1.

＜Surface resistivity＞ For each of the base films in the surface protective films of Examples 1 to 4, after aging for 7 days at room temperature, a resistivity meter (trade name "Hiresta-UP MCP-HT450", manufactured by Mitsubishi Chemical Analytech Co., Ltd. ) to measure the surface resistivity (Ω/□). In this measurement, the applied voltage was set to 10 V, and the voltage application time was set to 10 seconds. In addition, this measurement was performed in an environment of 23°C and 50%RH. The measurement results are listed in Table 1.

＜Measurement of adhesion to glass＞ The adhesion to the glass plane of each surface protective film of Examples 1 to 7 and Comparative Examples 1 and 2 was investigated. Specifically, first, after the surface protective film is aged for 7 days at room temperature, a test piece with a width of 25 mm and a length of 100 mm is cut out from the surface protective film. After peeling off the release liner from the test piece, press the test piece on its adhesive layer side to the glass plate (trade name "Blue plate cut and placed product (edged)" by using a 2 kg hand pressure roller in one reciprocating operation. Thickness 1.35 mm × width 100 mm × length 100 mm, manufactured by Shonami Glass Industry Co., Ltd.). After placing the test piece on the glass plate for 30 minutes in an environment of 23°C and 50% RH, use a universal tensile testing machine to conduct a peeling test on the test piece from the glass plate, and measure the adhesion to the glass (N/25 mm)". In this measurement, the peeling angle was set to 180°, and the stretching speed was set to 0.3 m/min. In addition, this measurement was performed in an environment of 23°C and 50%RH. The measurement results are listed in Table 1.

＜Followability of 3D glass plates＞ Each surface protective film of Examples 1 to 7 and Comparative Examples 1 and 2 was investigated for its ability to follow the surface of an adherend having uneven portions. Specifically, first, after the surface protective film is aged for 7 days at room temperature, a required number of sample films with a width of 210 mm and a length of 300 mm are cut out from the surface protective film. Next, after peeling off the release liner from the sample film, vacuum molding was performed using a vacuum molding machine (trade name "Vacuum molding machine NGF-0406-S", manufactured by Busch Vacuum Co., Ltd.). Hollow forming involves attaching the sample film on its adhesive layer side to a model glass plate with bevels on all four sides (thickness 1 mm × width 70 mm × length 150 mm, bevel length 2.5 mm, cross-sectional dimensions shown in Figure 3) The surface on the side of the inclined plane (in Figure 3, it is the surface except the lower surface in the figure). For each type of surface protection film, one sample film was used for lamination by vacuum pressure forming at a film heating temperature of 80°C, and another sample film was used for lamination by vacuum pressure forming at a film heating temperature of 130°C. The fit. After each lamination, use a cutting knife along the bottom periphery of the model glass plate with bevels on all four sides to cut and remove (trim) the remaining portion of the sample film (the portion not attached to the glass). Then, the presence or absence of bulging (partial peeling) of the sample film in the inclined portion of the model glass plate was visually observed and evaluated. The condition with no bulging after 2 days of application is rated as "good", the condition with bulging within 1 day after the first application is assessed as "good", and the application with bulges or wrinkles immediately after application is assessed as "good". "bad". The evaluation results are listed in Table 1. The surface protective film of Comparative Example 2 was bonded by vacuum pressure molding at a film heating temperature of 130° C. Since the film was thermally shrunk, it could not be implemented.

＜Workability of Surface Protection Film＞ The surface protective films of Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for installation workability on a vacuum pressure forming machine. Specifically, in the process of performing the above-mentioned followability evaluation test, the sample film (surface protective film) after peeling off the release liner was evaluated as being able to be installed without any problem in the installation operation of the vacuum pressure molding machine. "Good" is evaluated as "good" when the film is entangled due to static electricity generated after peeling off the release liner but can still be installed. "Good" is evaluated when the film is entangled due to static electricity generated after peeling off the release liner and the film itself has no plasticity. Therefore, if the installation operation is difficult, the evaluation is "poor". The evaluation results are listed in Table 1.

＜Repeelability＞ Two days after the bonding operation by the vacuum pressure forming described above for the followability evaluation test, the surface protective film was peeled off from the model glass plate manually. The ease of peeling off at this time was The properties were evaluated as re-peelability. Specifically, regarding the re-peelability of the surface protective film, the case where the surface protective film can be easily peeled off is evaluated as "good", and the case where the surface protective film is difficult to peel off is evaluated as "poor". The evaluation results are listed in Table 1.

＜Moisture resistance＞ For each surface protective film of Examples 1 to 7 and Comparative Examples 1 and 2, the so-called wettability of the adhesive layer or adhesive surface to the glass plane was investigated. Specifically, first, for the surface protective film, after aging for 7 days, a test piece with a width of 25 mm and a length of 100 mm was cut out from the surface protective film. After peeling off the release liner from the test piece, make one end area of the adhesive surface of the test piece (width 25 mm × length 5 mm) and a glass plate (trade name "Blue plate cut and placed product (edged)", thickness 1.35 mm × Width 100 mm × length 100 mm, manufactured by Shonami Glass Industry Co., Ltd.), hold the test piece in such a way that the angle formed by the test piece relative to the surface of the glass plate becomes an elevation angle of 20 to 30°. Secondly, when the test piece is released, the above-mentioned elevation angle gradually becomes smaller due to the weight of the test piece. At the same time, the contact area between the adhesive surface of the test piece and the surface of the glass plate gradually becomes larger. Through this process, the entire surface of the adhesive surface of the test piece is in contact with the surface of the glass plate. Glass plate surface contact. Measure the time required from the time point when the test piece is released until the entire adhesive surface of the test piece comes into contact with the surface of the glass plate. The measurement results are listed in Table 1.

[evaluation] The surface protective films of Examples 1 to 7 having the structure of the present invention all obtained good results in the above-mentioned followability evaluation test. In contrast, the surface protective films of Comparative Examples 1 and 2 did not obtain good results in the above-mentioned followability evaluation test.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2 base film Kind F ₂ F ₂ F ₃ F ₄ F ₁ F ₁ F ₁ F ₆ F ₅ Thickness(μm) 38 38 50 50 38 38 38 38 40 antistatic layer have have have have without without without without without Surface resistivity (Ω/□) 4.0×10 ⁹ 4.0×10 ⁹ 7.9×10 ⁸ 1.5×10 ⁷ - - - - - Storage elastic modulus (MPa) 30℃ 2900 2900 2800 2800 2900 2900 2900 3800 950 80℃ 1000 1000 1100 1100 1000 1000 1000 3200 250 130℃ 40 40 80 80 40 40 40 770 - adhesive layer Kind Acrylic Acrylic Acrylic Acrylic Acrylic Urethane series Acrylic Acrylic Acrylic Thickness(mm) 20 20 20 20 20 10 5 20 5 Adhesion to glass (N/25 mm) 0.11 0.07 0.10 0.10 0.11 0.02 0.17 0.11 0.13 Followability 80℃ good good good good good good good Can bad 130℃ good good good good good good good Can - Re-peelability 80℃ good good good good good good good good good 130℃ good good good good good good good good - Installation workability good good good good Can Can Can Can bad Humidity (seconds/100 mm) 40 30 40 40 40 10 80 40 >100

Changes in the invention described above are noted below. [1] A surface protection film having a laminated structure including a base film having a storage elastic modulus at 130°C of 700 MPa or less and a storage elastic modulus at 30°C of 1,000 MPa or more, and Adhesive layer. [2] The surface protective film according to the above [1], wherein the base film has a laminated structure including an antistatic layer. [3] The surface protective film according to the above [2], wherein the antistatic layer contains an antistatic agent having a quaternary ammonium group and/or a conductive polymer. [4] The surface protective film according to any one of [1] to [3] above, wherein the material constituting the base film contains polyester. [5] The surface protective film according to any one of [1] to [4] above, wherein the adhesive layer contains an acrylic polymer and/or a urethane polymer. [6] The surface protective film according to any one of the above [1] to [5], which is a vacuum pressure forming lamination type film. [7] An optical member including the surface protective film according to any one of [1] to [6] above. [Industrial availability]

The surface protective film of the present invention can be suitably used as a protective film for optical members whose exterior surfaces include uneven portions such as curved portions or flexed portions.

10: Film (surface protective film) 11:Substrate film 12: Adhesive layer 12a: Adhesive surface 20: Optical components 21:Surface 21a: Bend part 21b:flexion part

Figure 1 is a partial cross-sectional view of a surface protective film according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of an optical component according to another embodiment of the present invention. FIG. 3 shows the cross-sectional dimensions of the model glass plate used in the followability evaluation test of the surface protective film of Examples and Comparative Examples.

10: Film (surface protective film)

11:Substrate film

12: Adhesive layer

12a: Adhesive surface

Claims (7)

A surface protection film having a laminated structure. The laminated structure includes: a storage elastic modulus at 130°C of 700 MPa or less, a storage elastic modulus of 30°C or more than 1000 MPa, and a storage elastic modulus of 700~ at 80°C. A base film of 1100 MPa and an adhesive layer; the material constituting the base film includes polyester, and the dicarboxylic acid constituting the polyester includes terephthalic acid and isophthalic acid. The surface protection film of claim 1, wherein the base film has a laminated structure including an antistatic layer. The surface protection film of claim 2, wherein the antistatic layer contains an antistatic agent with a quaternary ammonium group and/or a conductive polymer. The surface protective film according to any one of claims 1 to 3, wherein the glycols constituting the polyester include ethylene glycol and diethylene glycol. The surface protection film according to any one of claims 1 to 3, wherein the adhesive layer contains an acrylic polymer and/or a urethane polymer. The surface protection film according to any one of claims 1 to 3 is a vacuum pressure forming laminating film. An optical member including the surface protection film according to any one of claims 1 to 6.