JP2002172743A - Surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film not damaging the quality feeling of an object to be protruded even if bonded to the object to be protected and having an excellent abrasion-resistant surface. SOLUTION: The surface protective film is obtained by providing an undercoat layer and an ionizing radiation curable resin layer on one surface of a transparent base material, and providing a pressure-sensitive layer to the opposite surface thereof. The undercoat layer contains an acrylic resin with a glass transition temperature of -20-65 deg.C as a film forming component, and the acrylic resin comprises a copolymer containing a monomer having an unsaturated ethylene group or which the solubility coefficient as a homopolymer is 17.5-<20.0 (J/cm3)1/2 and a monomer of which the solubility coefficient as a homopolymer is 20.0 (J/cm3)1/2 or more at least as monomer components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protection film suitable for protecting the surface of various display materials, printed materials, photographs, etc., particularly without impairing the texture of the surface of the object to be protected.
The present invention relates to a surface protection film having an extremely excellent wear-resistant surface.

[0002]

2. Description of the Related Art An original plate, an advertisement,
2. Description of the Related Art Protective films are used for the purpose of preventing stains and scratches on the surface of display objects, photographs, and the like formed by various printing methods and the like for signs.

As such a protective film, a film provided with a protective layer having excellent abrasion resistance on the surface of a film serving as a base material is used in order to prevent the surface of the protective film itself from being damaged. As such a protective layer, an ionizing radiation-curable resin layer formed of an ionizing radiation-curable composition or the like is generally used because it can be formed to be thin while having excellent wear resistance.

On the other hand, such protective films include:
Since a relatively thick film is used, if it is attached to the surface of the object to be protected, the texture of the surface becomes that of the protective film, and the texture of the object to be protected is lost.

[0005] Therefore, in order to prevent the texture of the object to be protected from being impaired, if a protective film using a relatively thin film as a base film is to be used, when the protective film is adhered to the object to be protected, it is stuck neatly. Must be done while applying tension. Then, in the protective film having the above-described protective layer made of the ionizing radiation-curable resin layer having excellent wear resistance, the protective layer composed of the ionizing radiation-curable resin layer is generally a hard coating film. Since the protective layer is hardly stretched, it has a drawback that the protective layer is easily peeled off from the base film by the tension applied to the protective film.

Therefore, at present, there is no protective film which is a thin protective film which does not impair the texture of the protective object even if it is attached to the protective object and which has an excellent wear-resistant surface. .

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for improving the adhesion between an ionizing radiation-curable resin layer, which is a surface protective layer having excellent abrasion resistance, and a substrate film.
It is an object of the present invention to provide a surface protective film that does not impair the texture of the object to be protected even when attached to the object to be protected and has an excellent wear-resistant surface.

[0008]

In order to achieve the above object, the surface protective film of the present invention comprises an undercoat layer and an ionizing radiation-curable resin layer on one surface of a transparent substrate in this order, and an adhesive layer on the other surface. A surface protective film provided with a layer, wherein the undercoat layer contains, as a film-forming component, an acrylic resin having a glass transition temperature of −20 ° C. or more and 65 ° C. or less, and the acrylic resin has a solubility when formed into a homopolymer. Coefficient is 1
A monomer having an unsaturated ethylene group of 7.5 (J / cm ³ ) ^1/2 or more and less than 20.0 (J / cm ³ ) ^1/2 and a homopolymer having a solubility coefficient of 20.0 (J / cm ³ ) / cm ³ ) A copolymer containing at least a monomer of ^1/2 or more as a monomer component.

The surface protective film of the present invention is characterized in that the thickness of the surface protective film is 50 μm or less.

[0010] The surface protective film of the present invention is characterized in that the monomer having an unsaturated ethylene group constituting the acrylic resin contains a (meth) acrylic ester having an alkyl group having 2 to 12 carbon atoms. Is what you do.

Further, the surface protective film of the present invention has a solubility coefficient of 20.0 (J / cm ³ ) when made into a homopolymer.
It is characterized by containing methyl methacrylate as a monomer having a ratio of ^1/2 or more.

Further, the surface protective film of the present invention has a solubility coefficient of 20.0 (J / cm ³ ) when made into a homopolymer.
It is characterized by containing 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole as a monomer having a ratio of ^1/2 or more.

The solubility coefficient (hereinafter referred to as "SP value") in the present invention is obtained by the following equation. In the following, when described as “SP value”, it means the SP value of a homopolymer when the monomer is homopolymerized, and the SP value is simply a numerical value, and its unit “ (J / cm ³ ) ^1/2 ”is omitted.

[0014]

(Equation 1) δ: SP value F _di : molar dispersion contribution term F _pi : molar polar force attractive term E _hi : molar hydrogen bond attractive term V: sum of molar volumes of each atomic group

This SP value is based on the atomic group sum method proposed by von Kreevelen.
ndbook, Fourth Edition, John Wiley & Sons, Inc., 1999
VII / 675 to VII / 686. Table 1 shows examples of each parameter for reference.

[0016]

[Table 1]

In Table 1, "tBu" is a tertiary butyl group, "CyHex" is a cyclohexyl group, and "Ph"
“1” to “Ph6” represent a phenyl group having 1 to 6 substituents,
ing> = 5 ”is a cyclic hydrocarbon having 5 or more carbon atoms, and“ R
"ing <= 4" means a cyclic hydrocarbon having 4 or less carbon atoms.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the surface protective film of the present invention will be described in detail.

The surface protective film of the present invention has a structure in which an undercoat layer and an ionizing radiation-curable resin layer are provided in this order on one surface of a transparent substrate, and an adhesive layer is provided on the opposite surface.

Here, as the transparent substrate, polyethylene terephthalate, polycarbonate, polypropylene,
A plastic film such as polyethylene, polyvinyl chloride, polyethylene naphthalate, and polystyrene which does not hinder transparency is used. Especially for some applications
In some cases, a material having a low or high ultraviolet transmittance is suitable. In addition, a biaxially stretched polyethylene terephthalate film is preferably used because it is excellent in strength, heat resistance, dimensional stability, and the like. The thickness of the transparent substrate is preferably 50 μm or less, preferably 30 μm or less, more preferably 15 μm or less, so as not to impair the texture of the protection target when attached to the protection target. In consideration of this, it is desirable that the thickness be 1 μm or more, preferably 2 μm or more, and more preferably 4 μm or more.

The undercoat layer is a layer having a property of enhancing the adhesiveness of the ionizing radiation-curable resin layer to the transparent substrate,
Thereby, it is possible to obtain a surface protective film which is a thin protective film and which has an excellent wear-resistant surface without impairing the texture of the protective object even when the protective film is attached to the protective object. become. The undercoat layer provided between such a transparent substrate and the ionizing radiation-curable resin layer needs to contain a specific acrylic resin as a film-forming component.

The acrylic resin has a glass transition temperature:
The lower limit is -20 ° C or higher, preferably 0 ° C or higher,
The upper limit is 65 ° C. or lower, preferably 50 ° C. or lower.
By setting the content in such a range, the adhesiveness between the transparent substrate and the ionizing radiation-curable resin layer can be improved. The acrylic resin has an SP value of 17.
A copolymer containing at least a monomer having an unsaturated ethylene group of 5 or more and less than 20.0 and a monomer having an SP value of 20.0 or more as a monomer component. By copolymerizing such monomer components, the adhesiveness between the transparent substrate and the ionizing radiation-curable resin layer can be improved.

The monomer having an unsaturated ethylene group having an SP value of 17.5 or more and less than 20.0 has 2 to 2 carbon atoms.
It is preferable to include a (meth) acrylate having 12 alkyl groups. By incorporating a (meth) acrylate having an alkyl group having 2 to 12 carbon atoms, the adhesiveness to the ionizing radiation-curable resin layer can be further improved. Examples of such (meth) acrylic acid esters include butyl acrylate, butyl methacrylate and 2-ethylhexyl acrylate.

Next, various monomers such as methyl acrylate and methyl methacrylate can be contained as a monomer having an SP value of 20.0 or more. However, methyl methacrylate is excellent in polymerization easiness and the like. It is preferred to include. Use of vinyl acetate, vinyl propionate, vinyl ether, (meth) acrylonitrile, or the like is preferable in that the adhesiveness to a transparent substrate such as a plastic film can be further improved. Also,
monomers having a carboxyl group such as β-carboxyethyl acrylate, acrylic acid, itaconic acid, crotonic acid, maleic acid, and maleic anhydride; 2-hydroxyethyl (meth) acrylate; 2-hydroxypropyl (meth) acrylate; Hydroxybutyl (meth)
Acrylate, diethylene glycol mono (meth) acrylate, a monomer having a hydroxyl group such as allyl alcohol, aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, When a monomer containing an amino group such as vinylpyridine, a monomer containing an acetoacetoxyethyl group such as acetoacetoxyethyl (meth) acrylate, or a monomer containing an epoxy group such as glycidyl (meth) acrylate is used, aggregation of the coating film occurs. It is preferable in that it can improve the force and impart a crosslinking point.

In order to obtain the light resistance of the surface protective film, it is necessary to include a benzophenone-based or benzotriazole-based monomer having an ultraviolet absorbing group as the monomer having the SP value of 20.0 or more. Is preferable, and particularly, 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H— represented by the following formula (1):
Benzotriazole (hereinafter simply “benzotriazole”
), It is possible to obtain a surface protective film having a high ultraviolet absorbing effect, and it is also possible to prevent fading of an object to be protected.

[0026]

Embedded image

The acrylic resin containing benzotriazole as a monomer component has absorptivity to light of 290 nm to 400 nm, does not cause bleeding due to the introduction of an ultraviolet absorbing group into the acrylic resin, and is cured by ionizing radiation. The adhesiveness with the mold resin layer is also good.

The acrylic resin of the present invention includes, in addition to the monomer having an unsaturated ethylene group having the SP value of 17.5 or more and less than 20.0, the monomer component having the SP value of 20.0 or more, Other polymerizable monomer components within a range that does not hinder the polymerization.

The glass transition temperature of the acrylic resin can be adjusted by changing the polymerization ratio of these polymerization components.

The undercoat layer of the present invention is obtained by mixing a resin having good adhesion to the transparent substrate with the specific acrylic resin of the present invention in order to further enhance the adhesion to the transparent substrate. It can also be formed. When the transparent substrate is a plastic film of a polyester resin, examples of such a resin include a polyester resin and a vinyl acetate resin.

Further, the undercoat layer may be mixed with the acrylic resin and the resin having good adhesiveness to the transparent substrate, as well as other resins within a range not to impair these effects.

When a resin other than the above-mentioned acrylic resin is mixed, the content of the above-mentioned acrylic resin is preferably 50% by weight or more of the resin constituting the undercoat layer, although it cannot be said unconditionally depending on the resin to be mixed. Is contained in an amount of 80% by weight or more. By setting the content in such a range, the adhesiveness to the transparent substrate and the ionizing radiation-curable resin layer can both be improved.

The undercoat layer may contain additives such as a pigment, an antifoaming agent, a leveling agent, a light stabilizer, and a crosslinking agent, in addition to the above-mentioned resin and the like. However, it is desirable that the amount of these additives be within a range that does not impair the effect of the undercoat layer.

The undercoat layer is formed by applying a coating solution obtained by dissolving or dispersing the above-mentioned resin constituting the undercoat layer and, if necessary, an additive in a solvent to the surface of a transparent substrate by a conventionally known coating method, and drying the coating solution. Can be formed. The thickness of the undercoat layer is set at 0.0 to make the adhesiveness between the transparent substrate and the ionizing radiation-curable resin layer sufficient.
5 μm or more, preferably 0.1 μm or more, more preferably 0.5 μm or more, and the thickness of the entire surface protective film is increased so as not to impair the texture of the object to be protected when attached to the object to be protected. 10μ to make
m or less, preferably 5 μm or less, more preferably 3 μm
It is desirable that:

The ionizing radiation-curable resin layer is present on the surface of the surface protective film of the present invention, and has a high surface hardness formed from a composition which can be cross-linked and cured by irradiation with ionizing radiation (ultraviolet rays or electron beams). A resin layer having excellent abrasion resistance, which is formed of one layer or two or more layers. A multilayer ionizing radiation-curable resin layer, such as a lamination of a first ionizing radiation-curable resin layer with an emphasis on adhesion to the undercoat layer and a second ionizing radiation-curable resin layer with an emphasis on surface hardness. It is effective to do.

As the ionizing radiation-curable composition for forming such an ionizing radiation-curable resin layer, a paint obtained by mixing one or more of a photopolymerizable prepolymer and a photopolymerizable monomer can be used. Can be.

As the photopolymerizable prepolymer, an acrylic prepolymer having two or more acryloyl groups in one molecule and having a three-dimensional network structure by crosslinking and curing is particularly preferably used. As the acrylic prepolymer, urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate and the like can be used.

Examples of the photopolymerizable monomers include trimethylolpropane trimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, neopentyl glycol diacrylate, tripropylene glycol triacrylate, and diethylene glycol diacrylate. And polyfunctional monomers such as 1,6-hexanediol diacrylate.

In addition to the ionizing radiation-curable composition, a matting agent, a plasticizer, an antioxidant, a coloring agent, a lubricant, etc. Various additives such as an antistatic agent, a flame retardant, an antibacterial agent, and a fungicide can be contained. Particularly, when ultraviolet rays are used for curing, the crosslinking curability and the hardness of the crosslinked cured coating film are improved. It is preferable to add a photopolymerization initiator, an ultraviolet sensitizer and the like in order to improve the efficiency. Examples of the photopolymerization initiator include acetophenone, benzophenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoin benzoate, α-acyloxime ester, thioxanthones, and the like. n-butylphosphine and the like.

The ionizing radiation-curable resin layer may contain, in addition to the ionizing radiation-curable composition, other binder components as long as its performance is not impaired. For example, a thermoplastic resin or a thermosetting resin having no ionizing radiation curability can be mixed. When other binder components are mixed with the ionizing radiation-curable composition as described above, the content of the ionizing radiation-curable composition is set to 50% by weight or more of the binder component constituting the ionizing radiation-curable resin layer, preferably It is desirable that the content be 80% by weight or more.

The coating liquid prepared by mixing the ionizing radiation-curable composition with other binder components, additives, diluting solvents and the like, if necessary, is subbed by a conventionally known coating method or the like. An ionizing radiation-curable resin layer can be formed by forming a film by coating, drying, and curing the layer. At the time of curing, 100 to 400 n emitted from an ultra-high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, carbon arc, metal halide lamp, or the like.
m, preferably in the range of 200 to 400 nm, or by irradiation with ionizing radiation such as an electron beam in a wavelength range of 100 nm or less emitted from a scanning or curtain type electron beam accelerator. The thickness of the ionizing radiation-curable resin layer is preferably 0.5 μm or more, preferably 1 μm or more, more preferably 2 μm or more in order to obtain sufficient abrasion resistance, and the thickness of the entire surface protective film is increased. 15 μm to prevent the texture of the object to be protected from being impaired when attached to the object to be protected
Below, it is desirable that it is 10 μm or less, more preferably 5 μm or less.

The pressure-sensitive adhesive layer provided on the surface opposite to the surface on which the undercoat layer of the transparent base material and the ionizing radiation-curable resin layer are provided is made of a generally used acrylic pressure-sensitive adhesive or rubber-based pressure-sensitive adhesive. The thickness of the adhesive layer is 0.5 μm or more, preferably 1
μm or more, more preferably 2 μm or more, and preferably 15 μm or less, more preferably 15 μm or less, so as not to impair the texture of the object to be protected when the entire surface protective film is thickened and adhered to the object to be protected. Is 10 μm or less,
More preferably, the thickness is 5 μm or less.

Further, in order to prevent the handleability of the surface protective film from being deteriorated by the adhesiveness, a release film having a release treatment applied to a surface of a plastic film, paper, or the like is bonded to the adhesive layer. Can also be performed as appropriate.

The surface protective film as described above has a subbing layer having a function of enhancing the adhesion of the ionizing radiation-curable resin layer to the transparent substrate, so that the protective film is thin and adheres to the object to be protected. However, the surface of the object to be protected has an excellent wear-resistant surface without impairing the texture. Here, the thickness of the entire surface protection film is 50 μm or less, preferably 30 μm or less, so as not to impair the texture of the protection object when attached to the protection object.
More preferably, it is desirable to be 20 μm or less.

[0045]

Embodiments of the present invention will be described below.
The “parts” and “%” are based on weight unless otherwise specified.

[Examples 1 to 13] Synthesis of Acrylic Resin A reaction vessel equipped with a stirrer, a condenser, a thermometer and a nitrogen inlet tube was charged with 9 parts of ethyl acetate and 12 parts of methyl ethyl ketone.
And 9 parts of toluene, and the mixture was stirred while passing nitrogen gas at 80 ° C.
Heated. In another container, the monomer components shown in Table 2, and
6 parts of ethyl acetate, 8 parts of methyl ethyl ketone, 6 parts of toluene
Part, α, α′-azobis (isobutyronitrile) 0.1
Five parts were mixed, and the mixture was dropped into the above reaction vessel over 1 hour and 30 minutes. During this time, the reaction solution was kept at 80 ° C. and kept stirring. Thereafter, the reaction solution was further heated at 80 ° C. for 6 hours and 30 minutes.
The reaction was completed while stirring to complete the reaction. To this, 15 parts of ethyl acetate, 20 parts of methyl ethyl ketone and 15 parts of toluene were added to adjust the solid content to 50%, and acrylic resins A to M shown in Table 2 were obtained. These acrylic resins A ~
When the weight average molecular weight of M was measured by GPC (polystyrene conversion), it was in the range of 300,000 to 600,000.

[0047]

[Table 2]

In Table 2, "Tg" is the glass transition temperature, and "BA" is butyl acrylate (SP value = 19.3
2), “BMA” is butyl methacrylate (SP value = 19.
08), “2-EHA” is 2-ethylhexyl acrylate (SP value = 18.33), “MMA” is methyl methacrylate (SP value = 20.64), “FA-513M” is tricyclo [5.2.1.0 ^{2, 6} ] Deca-8-yl-methacrylate (SP value = 20 or more), “AA” is acrylic acid (S
P value = 27.01), "RUVA-93" is 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H
-Benzotriazole (SP value = 20 or more), "VAc"
Represents vinyl acetate (SP value = 21.51). These SPs
The value is the SP value of the homopolymer when the monomer is homopolymerized as described above.

Hereinafter, an example of calculating the SP value will be shown taking the case of butyl acrylate (formula (2)) as an example.

[0050]

Embedded image

[0051]

[Table 3]

[0052]

(Equation 2)

2. Preparation of Surface Protective Film Using the acrylic resins A to M in Table 2, an undercoat layer coating solution having the following composition was prepared, and this was coated on one side of a 4 μm-thick polyethylene terephthalate film (Lumirror F53: Toray Industries, Inc.). An undercoat layer having a thickness of about 2 μm was formed by applying the composition on the surface and drying. Next, on the undercoat layer, a coating liquid for an ionizing radiation-curable resin layer having the following composition is applied and dried,
The resin was cured by irradiating ultraviolet rays for 1 to 2 seconds with a high-pressure mercury lamp to form an ionizing radiation-curable resin layer having a thickness of about 4 μm. Further, a coating solution for the adhesive layer having the following composition was applied to the other surface and dried to form an adhesive layer having a thickness of about 5 μm, thereby producing a surface protective film. A 25 μm-thick polyethylene terephthalate release film (MRB: Mitsubishi Chemical Polyester Film Co., Ltd.) was attached to the adhesive layer for handling.

<Coating liquid for undercoat layer> 11.0 parts of acrylic resin <50% of solid content> 1.0 part of polyester resin (Acryt ER20 <40% of solid content: Taisei Kako Co., Ltd.) 1.0 part of methyl ethyl ketone 0 parts ・ Toluene 11.0 parts ・ Cyclohexanone 6.0 parts

<Coating liquid for ionizing radiation-curable resin layer> ・ Ionizing radiation-curable paint (Diabeam UR6530: Mitsubishi Rayon Co., Ltd.) 40.0 parts ・ Photopolymerization initiator (Irgacure 651: Ciba Specialty Chemicals Co., Ltd.) ) 0.6 parts ・ Methyl ethyl ketone 40.0 parts ・ Toluene 40.0 parts

<Coating liquid for adhesive layer> Acrylic ester copolymer (Arontack SCL-200 <solid content 40%>: Toagosei Chemical Co., Ltd.) 10.0 parts ・ Toluene 10.0 parts ・ Ethyl acetate 0 copies

Comparative Example 1 A coating liquid for an ionizing radiation-curable resin layer having the composition of the example was applied to one surface of a polyethylene terephthalate film (Lumirror F53: Toray Industries, Ltd.) having a thickness of 4 μm, dried, and dried with a high-pressure mercury lamp. Curing by irradiating ultraviolet rays for 1 to 2 seconds to form an ionizing radiation-curable resin layer having a thickness of about 4 μm, applying a coating liquid for an adhesive layer having the composition of the example on the opposite surface, and drying the coating. , Film thickness about 5
A surface protective film was prepared by forming a μm adhesive layer. A 25 μm-thick polyethylene terephthalate release film (MRB: Mitsubishi Chemical Polyester Film Co., Ltd.) was attached to the adhesive layer for handling.

Using the laminator (Kimotech Laminator IV: Kimotosha), the adhesive layer exposed while peeling off the release film was applied to the surface protective films of Examples and Comparative Examples obtained as described above. After adhering on the image formed on the ink jet printing paper by printing, the surface state of the surface protective film was observed and evaluated, and the printed matter whose surface was protected by the surface protective film of Examples 1 to 13 was No particular problem was found in the surface condition, and an excellent abrasion-resistant surface was obtained without impairing the texture of an image formed by inkjet printing. On the other hand, the surface state of the surface protective film of Comparative Example 1 was such that the ionizing radiation-curable resin layer was cracked and partially peeled off from the film surface due to the tension of the laminator at the time of sticking.

In the surface protective films of Examples 7 to 13, the SP value, which is a component of the acrylic resin, was 2%.
Since benzotriazole, which is a UV-absorbing monomer, was contained as a monomer having a value of 0.0 or more, a surface protective film having excellent light resistance as compared with the other monomers was obtained.

[0060]

According to the surface protective film of the present invention, the undercoat layer and the ionizing radiation-curable resin layer are provided in this order on one surface of the transparent substrate, and the adhesive layer is provided on the other surface. The layer contains an acrylic resin having a glass transition temperature of −20 ° C. or more and 65 ° C. or less as a film-forming component, and has a solubility coefficient of 1 when the acrylic resin is a homopolymer.
A monomer having an unsaturated ethylene group of 7.5 (J / cm ³ ) ^1/2 or more and less than 20.0 (J / cm ³ ) ^1/2 and a homopolymer having a solubility coefficient of 20.0 (J / cm ³ ) ^/ cm ^{3) 1} / by a copolymer containing ² or more than monomer is at least as monomer components, increase the adhesion between the ionizing radiation-curable resin layer and the substrate film is a surface protective layer having excellent abrasion resistance By doing so, it becomes possible to obtain a surface protective film having an excellent wear-resistant surface without impairing the texture of the protective object even when the protective film is attached to the protective object.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Susumu Kurishima, 4-6-135 Suzuya, Yono-shi, Saitama Prefecture Inside the Kimoto R & D Center, Inc. (72) Koji Matsuyama 4-6-35, Suzuya, Yono-shi, Saitama No. F-term in Kimoto R & D Center (reference) 4F100 AK01C AK02B AK25B AL01B BA04 BA10C BA10D CB05D GB90 JA05B JB08B JB14C JK09 JL13D JN01A YY00 YY00B 4J004 AB01 CA03 CC03 FA04

Claims (5)

[Claims] An undercoat layer and an ionizing radiation curable resin layer are provided in this order on one surface of a transparent substrate, and an adhesive layer is provided on the other surface, and the undercoat layer is made of glass. An acrylic resin having a transition temperature of −20 ° C. or more and 65 ° C. or less is included as a film-forming component, and the acrylic resin is
The solubility coefficient of the homopolymer is 17.5 (J / c
m ³ ) ^1/2 or more and less than 20.0 (J / cm ³ ) ^1/2 having a monomer having an unsaturated ethylene group and a solubility coefficient of 20.0 (J / cm ³ ) ^{1 /} A surface protective film, which is a copolymer containing at least ^two monomers as a monomer component. 2. The surface protective film according to claim 1, wherein the thickness of the surface protective film is 50 μm or less. 3. The monomer having an unsaturated ethylene group has an alkyl group having 2 to 12 carbon atoms (meth).
The surface protective film according to claim 1, comprising an acrylic ester. 4. The solubility coefficient is 20.0 (J / cm ³ ) ^1/2.
The surface protective film according to claim 1, wherein the monomer includes methyl methacrylate. 5. The method according to claim 1, wherein said solubility coefficient is 20.0 (J / cm ³ ) ^1/2.
As the above monomer, 2- (2′-hydroxy-
The surface protective film according to claim 1, comprising 5'-methacryloxyethylphenyl) -2H-benzotriazole.