JP6844057B1 - Cover film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover film for a bending display and a method for manufacturing the same, which have both bending resistance and high surface hardness. SOLUTION: The cover film for a bent display includes a transparent base material layer 1 and a transparent surface layer 2 laminated on one surface of the base material layer, and the base material layer is urethane-based. It contains (meth) acrylate and bifunctional or higher functional (meth) acrylate, the surface layer contains tetrafunctional or higher functional (meth) acrylate, and the base material layer contains 50 of the urethane-based (meth) acrylate. The surface layer contains 65 parts by weight or more of tetrafunctional or higher (meth) acrylate, the thickness of the surface layer is 40 μm or more, and the thickness of the base material layer is 45 μm or more and 85 μm or less. .. [Selection diagram] Fig. 1

Description

The present invention relates to a cover film and a method for producing the same.

In recent years, various cover films that protect the surface of displays such as smartphones have been proposed. As such a cover film, for example, Patent Document 1 proposes a cover film having a hard coat layer and a transparent film. This transparent film is produced as follows. For example, in Patent Document 1, an ultraviolet curable acrylic resin is applied on a first base film, a second base film is further laminated on the ultraviolet curable acrylic resin, and then an ultraviolet ray is irradiated to obtain a cross-linking rate. Curing is performed so that the value is 40 to 60%. In this way, a transparent film is formed from the ultraviolet curable acrylic resin. Next, after peeling off the two base films, an ultraviolet curable resin for a hard coat layer containing fluorine is applied onto the transparent film and irradiated with ultraviolet rays. In this way, the ultraviolet curable resin is cured and a hard coat layer is formed. Through the above steps, a cover film having a transparent film and a hard coat layer is formed.

JP-A-2017-159506

In the cover film as described above, high surface hardness is required in addition to bending resistance. However, as a cover film having both bending resistance and high surface hardness, a cover film having sufficient performance has not yet been proposed, and there is room for improvement. The present invention has been made to solve the above problems, and an object of the present invention is to provide a cover film for a bending display and a method for manufacturing the same, which have both bending resistance and high surface hardness.

Item 1. A cover film for flexible displays
With a transparent substrate layer,
A transparent surface layer laminated on at least one surface of the base material layer,
With
The base material layer contains a urethane-based (meth) acrylate and a bifunctional or higher functional (meth) acrylate.
The surface layer contains a tetrafunctional or higher functional (meth) acrylate and contains.
The base material layer contains 50 parts by weight or more of the urethane-based (meth) acrylate.
The surface layer contains 65 parts by weight or more of the tetrafunctional or higher (meth) acrylate.
The thickness of the surface layer is 40 μm or more.
A cover film having a base material layer having a thickness of 45 μm or more and 85 μm or less.

Item 2. Item 2. The cover film according to Item 1, wherein the surface layer further contains 10 parts by weight or more of trifunctional or less functional (meth) acrylate.

Item 3. Item 2. The cover film according to Item 1 or 2, wherein the base material layer contains 15 parts by weight or more of the low-viscosity bifunctional or higher (meth) acrylate.

Item 4. Item 2. The cover film according to any one of Items 1 to 3, wherein the base material layer further contains a trifunctional or higher functional (meth) acrylate.

Item 5. A step of laminating a resin composition for a base material layer containing a urethane-based (meth) acrylate and a bifunctional or higher functional (meth) acrylate on a support film.
A step of cross-linking the resin composition for a base material layer so that the cross-linking rate is 90% or less.
A step of laminating a surface layer precursor containing a tetrafunctional or higher functional (meth) acrylate on the resin composition for a base material layer,
A step of curing the resin composition for a base material layer and the resin composition for a surface layer to form a cover film having a base material layer and a surface layer.
With
The thickness of the surface layer is 40 μm or more.
A method for producing a cover film, wherein the thickness of the base material layer is 45 μm or more and 85 μm or less.

According to the cover film according to the present invention, both bending resistance and high surface hardness can be achieved.

It is sectional drawing of a cover film. It is a schematic diagram which shows the bending tester and its usage.

Hereinafter, an embodiment of the cover film according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of this cover film. As shown in FIG. 1, the cover film according to the present invention is laminated on at least one surface of the transparent base material layer 1 and the base material layer 1, and is harder and more transparent than the base material layer 1. 2 and. Hereinafter, each layer will be described in detail. In the specification, the numerical values connected by "-" mean a numerical range including the numerical values before and after "-" as the lower limit value and the upper limit value. Further, when a plurality of lower limit values and a plurality of upper limit values are described separately, any lower limit value and upper limit value can be selected and connected by "~".

<1. Base layer>
The base material layer 1 according to the present invention is an ionizing radiation curable resin containing a radically polymerizable compound that polymerizes or undergoes a cross-linking reaction by ionizing radiation (ultraviolet rays or electron beams). Specifically, it can be a resin material containing a urethane-based (meth) acrylate and a bifunctional or higher functional (meth) acrylate. Further, if necessary, the base material layer 1 may be blended with a trifunctional or higher functional (meth) acrylate, a polymerization initiator or an additive, which will be described later. The term "bifunctional or higher" means that, for example, the structural unit contains at least two ethylenically unsaturated bonds. This point is the same for the surface layer 2 described later.

<1-1. Urethane-based (meth) acrylate>
Examples of the urethane-based (meth) acrylate include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate. Toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer and the like can be used.

The weight average molecular weight of the urethane-based (meth) acrylate is, for example, preferably 1000 to 10000, and more preferably 2000 to 5000. Further, as a method for measuring the molecular weight, the GPC method can be used.

<1-22.2 functional or higher (meth) acrylate>
Examples of the bifunctional compound containing two unsaturated bonds include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and nonanediol di. (Meta) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene Di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. (Meta) acrylate and the like can be mentioned. Such bifunctional or higher functional (meth) acrylates have a relatively low viscosity, for example, preferably 300 mPa · s (25 ° C.) or less, and more preferably 100 mPa · s (25 ° C.) or less. , 50 mPa · s (25 ° C.) or less, more preferably.

<(Meta) acrylate with 1-3-3.3 functionality or higher>
Examples of the polyfunctional compound containing three or more unsaturated bonds include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and Tris2-. Tri (meth) acrylates such as hydroxyethyl isocyanurate tri (meth) acrylate and glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dimethylolpropane tri (meth) acrylate and the like. Trifunctional (meth) acrylate compound, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta Trifunctional or higher polyfunctional (meth) acrylate compounds such as (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and ditrimethylolpropane hexa (meth) acrylate, and some of these (meth) acrylates are alkyl groups or ε. -A (meth) acrylate compound such as a polyfunctional (meth) acrylate compound substituted with caprolactone can be mentioned. The viscosity of such a trifunctional or higher (meth) acrylate is higher than the viscosity of the bifunctional or higher (meth) acrylate described in <1-2>, for example, the viscosity is 1000 to 9000 mPa · s (25 ° C.). ), More preferably 1500 to 8500 mPa · s (25 ° C.), and even more preferably 2000 to 8000 mPa · s (25 ° C.).

<1-4. Content>
The urethane-based (meth) acrylate is preferably 50 to 90 parts by weight, more preferably 70 to 80 parts by weight, based on 100 parts by weight of the base material layer. When the urethane-based (meth) acrylate exceeds 90 parts by weight, it becomes difficult to manufacture the base material layer 1 due to its high viscosity. Further, if the urethane-based (meth) acrylate is less than 50 parts by weight, the bending resistance is lowered. On the other hand, the bifunctional or higher functional (meth) acrylate is preferably 15 to 50 parts by weight, more preferably 20 to 30 parts by weight, based on 100 parts by weight of the base material layer. Further, a plurality of types of (meth) acrylates may be contained. For example, a bifunctional (meth) acrylate and a trifunctional or higher functional (meth) acrylate described in item <1-3> can be contained. In this case, the trifunctional or higher functional (meth) acrylate described in item <1-3> is preferably 15 to 35 parts by weight with respect to 100 weight by weight of the base material layer. Examples of the combination of the bifunctional or higher low-viscosity (meth) acrylate and the trifunctional or higher (meth) acrylate include bifunctional low-viscosity (meth) acrylate and tetrafunctional (meth) acrylate, or 3 functional. Functional low-viscosity (meth) acrylates and hexafunctional (meth) acrylates can be used, but are not limited thereto.

<1-5. Photopolymerization initiator>
Examples of the polymerization initiator include benzylmethyl ketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methyl-1-phenylpropane-1. Α-Hydroxyketones such as −ON, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholino) Α-Aminoketones such as phenyl) butanone-1, bisacylphosphine oxides such as bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,2'-bis (o) -Chlorophenyl) -4,4', 5,5'-tetraphenyl-1,1'-biimidazole, bisimidazoles such as bis (2,4,5-triphenyl) imidazole, N such as N-phenylglycine Including organic azides such as -arylglycines and 4,4'-diazide chalcone, organic peroxides such as 3,3', 4,4'-tetra (tert-butylperoxycarboxyl) benzophenone, J. Photochem. Sci. Technol. 2,283 (1987). Can be mentioned.

Specific examples thereof include an iron arene complex, a trihalogenomethyl-substituted S-triazine, a sulfonium salt, a diazonium salt, a phosphonium salt, a selenium salt, an arsonium salt, and an iodonium salt. As the iodonium salt, Macromolecules, 10, 1307 (1977). , For example, diphenyliodonium, ditriliodonium, phenyl (p-anisyl) iodonium, bis (m-nitrophenyl) iodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium and the like. Iodonium chloride, bromide, or borofluoride salt, hexafluorophosphate salt, hexafluoroarsenate salt, aromatic sulfonate, etc., and sulfonium organic boron complex such as diphenylphenacil sulfonium (n-butyl) triphenylborate. Can be mentioned.

<1-6. Additives>
The following additives can be added as needed. For example, silicone-based and fluorine-based additives (for example, leveling agents) that impart leveling, surface slip property, low water contact angle, and the like can be mentioned. By blending such additives, the scratch resistance of the surface of the base material layer 2 can be improved. The blending amount of these additives is, for example, 0.01 with respect to 100 parts by weight of the base material layer. It can be ~ 0.5 parts by weight.

<1-7. Base layer thickness>
The thickness of the base material layer 1 is preferably, for example, 45 μm or more and 85 μm or less, and more preferably 50 μm or more and 80 μm or less.

<2. Surface layer>
Next, the surface layer 2 will be described. Similar to the base material layer 1, the surface layer 2 is also an ionizing radiation curable resin containing a radically polymerizable compound that polymerizes or undergoes a cross-linking reaction by ionizing radiation (ultraviolet rays or electron beams). Specifically, it can be a resin material containing a tetrafunctional or higher functional (meth) acrylate. In addition to this, trifunctional or less functional (meth) acrylates may be further contained. Similar to the base material layer 1, the surface layer 2 may be blended with a polymerization initiator or an additive described later, if necessary. In addition, "four or more functional" means that, for example, at least four ethylenically unsaturated bonds are contained in the structural unit. The viscosity of the trifunctional or lower (meth) acrylate is higher than the viscosity of the bifunctional or higher (meth) acrylate described in item <1-2> of the base material layer 1, for example, 300 to 7000 mPa · s (. 25 ° C.), more preferably 400 to 6000 mPa · s (25 ° C.), and even more preferably 500 to 5000 mPa · s (25 ° C.).

As the tetrafunctional or higher functional (meth) acrylate, the same material as the trifunctional or higher functional (meth) acrylate in the base layer 1 can be used. In addition, the same materials as those used for the base layer 1 can be used for the polymerization initiator and the additive.

The trifunctional or lower (meth) acrylate is preferably, for example, 10 to 35 parts by weight, and more preferably 15 to 30 parts by weight, based on 100 parts by weight of the surface layer. Further, the tetrafunctional or higher functional (meth) acrylate is preferably, for example, 65 to 90 parts by weight, more preferably 70 to 85 parts by weight, based on 100 parts by weight of the surface layer. Examples of the combination of trifunctional or lower (meth) acrylate and tetrafunctional or higher (meth) acrylate include trifunctional (meth) acrylate and tetrafunctional (meth) acrylate, or bifunctional (meth) acrylate. And 6-functional (meth) acrylates, but are not limited to this.

The thickness of the surface layer 2 is preferably 40 μm or more and 90 μm or less, more preferably 50 μm or more and 80 μm or less, and further preferably 60 μm or more and 75 μm or less. Since the surface layer 2 is a hard layer, the thickness needs to be 40 μm or more in order to increase the surface hardness measured by pencil hardness or the like. On the other hand, if it is too thick, the bending performance will deteriorate, which is not preferable.

Further, the surface layer 2 is preferably 5H or more, preferably 6H or more, and further preferably 7H or more in the surface pencil hardness test defined by JIS-K5600-5-4 (1999). ..

<3. Cover film manufacturing method>
The method for producing the cover film according to the present invention is not particularly limited, but for example, it can be produced as follows. First, the first base film is conveyed by roll-to-roll, and the resin composition for a base material layer prepared from the above-mentioned materials is applied onto the first base film, and then dried. The first base film may be formed of, for example, polyethylene terephthalate; polyamide; polycarbonate; acrylic resin; polyolefin resin such as polypropylene or polyethylene; cellulose resin such as diacetyl cellulose or triacetyl cellulose; polyvinylidene chloride or the like. it can.

As a method for applying the resin composition for the base material layer, for example, a known method such as a roll coater, a reverse roll coater, a gravure coater, a knife coater, or a bar coater can be adopted.

The method for drying the applied resin composition for the base material layer is not particularly limited. For example, a method of passing the first base film coated with the resin composition for the base material layer into the dryer can be mentioned. The drying temperature at this time is preferably, for example, 40 to 100 ° C. The above coating method and drying method are the same for the surface layer resin composition described later.

Next, the resin composition for the base material layer is irradiated with ionizing radiation and crosslinked. The cross-linking rate at this time is preferably 90% or less, and more preferably 50% or less. When the cross-linking rate of the resin composition for the base material layer exceeds 90%, the bond between the base material layer and the surface layer is weakened, so that the bending resistance is lowered. As the ionizing radiation source, it is preferable to use ultraviolet rays, and a light source such as a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a carbon arc, or a xenon arc can be used. This point is the same in the irradiation of the resin composition for the surface layer with ionizing radiation.

Subsequently, the surface layer resin composition prepared from the above-mentioned materials is applied onto the base material layer resin composition and dried. Further, a second base film containing fluorine is laminated on the surface layer resin composition. This second base film is a film having a coating layer containing a fluorine-based additive on a base film. This base film can be formed of the same material as the first base film. Further, the second base film is laminated so that the coating layer is in contact with the surface layer resin composition. Therefore, when the fluorine-based additive is added to the resin composition for the surface layer, the fluorine-based additive can be segregated on the outermost surface of the surface layer (the surface opposite to the base material layer).

Subsequently, ionizing radiation is irradiated to crosslink and cure the resin composition for the surface layer and the resin composition for the base material layer. Finally, if the first base film and the second base film are peeled off, the cover film according to the present invention is completed.

<4. Features>
According to the cover film according to the present embodiment, the following effects can be obtained.
(1) Since the cross-linking rate after applying the resin composition for the base material layer is 90% or less, and then the resin composition for the surface layer is applied and the entire surface is cross-linked, the base material layer 1 and the surface are crosslinked. The bond with the layer 2 becomes stronger, and the bending performance can be improved.
(2) The surface hardness of the surface layer 2 is increased by containing 65 parts by weight or more of tetrafunctional or higher functional (meth) acrylate. In addition to this, when a trifunctional or less functional (meth) acrylate is contained, the hardness does not become too high. This makes it possible to prevent cracks from occurring during bending.
(3) By setting the thickness of the surface layer 2 to 40 μm or more, the pencil hardness can be set to 5H or more.
(4) By having the base material layer containing the urethane-based (meth) acrylate, the stress at the time of bending can be alleviated, and the breakage of the cover film due to the occurrence of cracks in the surface layer 2 can be suppressed.
(5) By setting the thickness of the base material layer 1 to 45 μm or more and 85 μm or less, the bending resistance can be improved.

From the above, the cover film according to the present invention can be suitably used as a cover film for a bent display.

Next, examples of the present invention will be described. However, the present invention is not limited to the following examples.

<1. Preparation of Examples and Comparative Examples>
Hereinafter, the production of the cover film according to Examples 1 to 7 and Comparative Examples 1 to 5 will be described.

First, for the substrate layer, a trifunctional urethane-based acrylate (UV-7510B manufactured by Mitsubishi Chemical Co., Ltd.) having a viscosity of 800 to 1800 mPa · s (60 ° C.) (10000 mPa · s (25 ° C.) or higher) and a viscosity of 10 mPa · s (UV-7510B). A resin composition for a substrate layer containing a bifunctional (meth) acrylate (25 ° C.) (light acrylate 1.9ND-A manufactured by Kyoeisha Chemical Co., Ltd.) and a polymerization initiator (Omnirad1173 manufactured by IGM Resins BV) was prepared. Further, in Example 3 and Comparative Example 1, a hexafunctional (meth) acrylate having a viscosity of 4000 to 7000 mPa · s (25 ° C.) (light acrylate DPE-6A manufactured by Kyoeisha Chemical Co., Ltd.) was further contained.

On the other hand, for the surface layer, a bifunctional (meth) acrylate having a viscosity of 4000 to 7000 mPa · s (25 ° C.) (light acrylate DPE-6A manufactured by Kyoeisha Chemical Co., Ltd.) and a bifunctionality having a viscosity of 700 to 900 mPa · s (25 ° C.) Surface layer resin containing (meth) acrylate (light acrylate BP-4EAL manufactured by Kyoeisha Chemical Co., Ltd.), polymerization initiator (Omnirad1173 manufactured by IGM Resins BV), and fluorine additive (KY-1211 manufactured by Shinetsu Chemical Industry Co., Ltd.) The composition was prepared. The composition and thickness of the base layer and the surface layer are as shown in Table 1.

Next, as the first base film, a 100 μm-thick PET film (U48 manufactured by Toray Industries, Inc.) was prepared. Next, the resin composition for the base material layer was coated on the PET film using a wire bar coater. Then, the resin composition for the base layer was heat-treated at 80 ° C. for 2 to 5 minutes to dry the diluting solvent, and then using a UV irradiation device (manufactured by Heraeus Co., Ltd.) at an integrated light amount of ^{200 mJ / cm 2.} It was cured. The cross-linking rate at this time is as shown in Table 1.

Subsequently, the resin composition for the surface layer was coated on the partially crosslinked resin composition for the base material layer using a wire bar coater. Then, the above-mentioned second base film is laminated on the surface layer resin composition. The second base film is a film having an ultraviolet curable resin containing a fluorine additive on the same base film as the first base film and a hard coat layer having a thickness of 2 μm after curing on the surface.

Then, the same ultraviolet rays as described above were irradiated from the second base film to cure the surface layer resin composition and the base material resin composition. Finally, both base films were peeled off to obtain cover films according to Examples and Comparative Examples.

From the examples and comparative examples prepared as described above, a sample piece of 2.0 × 9.0 cm was cut out using a laser cutting device (GCC's SpiritGX laser output: 15 W, speed: 200 mm / sec). At this time, protective films were attached to both sides of the cover film, and a laser was irradiated on the protective films to cut the cover film. The protective film was a PET film having a thickness of 100 μm on which an adhesive layer having a thickness of 5 μm was laminated, and the adhesive layer was attached to the cover film.

<2. Evaluation test>
The surface pencil hardness test specified in JIS-K5600-5-4 (1999) was performed. Further, the sample pieces of each cover film prepared as described above were subjected to a test speed of 0.85 seconds / time, a bending diameter of φ1.5 mm, and a surface layer bent by using a no-load U-shaped tester shown in FIG. The number of times of repeated bending was measured so that it was placed inside when it was struck. More specifically, this testing machine has two movable plates that can be swiveled, and the rotation axes are arranged close to each other so that the rotation axes of the movable plates are parallel to each other. Then, with the sample piece of the cover film placed on the movable plate in the horizontal state shown in FIG. 2A, both movable plates are swiveled 90 degrees as shown in FIG. 2B to cover the cover. A sample piece of film was bent into a U shape. Then, the number of times of repeated bending until the sample piece of the cover film was broken was confirmed. The results are shown in Table 2 below.

In Comparative Example 1, since the content of urethane-based (meth) acrylate is low, the base material layer is hard. Therefore, it is considered that the flexibility is reduced. In Comparative Example 2, since the thickness of the base material layer is thin and the strength of the base material layer is low, it is considered that the stress of the surface layer cannot be absorbed when the cover film is bent and the flexibility is lowered. In Comparative Example 3, since the base material layer is thick, it is considered that the stress applied to the surface layer when the cover film is bent becomes large and the flexibility is lowered. In Comparative Example 4, since the film thickness of the surface layer is thin, the pencil hardness is low. In Comparative Example 5, it is considered that the pencil hardness is lowered because the amount of the hexafunctional (meth) acrylate contained in the surface layer is small.

On the other hand, it was found that Examples 1 to 7 did not have the problems of Comparative Examples 1 to 5 and had both bending resistance and high surface hardness.

1 base material layer 2 surface layer

Claims (5)

A cover film for flexible displays
With a transparent substrate layer,
A transparent surface layer laminated on at least one surface of the base material layer,
With
The base material layer contains a urethane-based (meth) acrylate and a bifunctional or higher functional (meth) acrylate.
The surface layer contains a tetrafunctional or higher functional (meth) acrylate and contains.
The base material layer contains 50 parts by weight or more and 90 parts by weight or less of the urethane-based (meth) acrylate with respect to 100 parts by weight of the base material layer.
The surface layer contains 65 parts by weight or more of the tetrafunctional or higher functional (meth) acrylate with respect to 100 parts by weight of the surface layer.
The thickness of the surface layer is 40 μm or more.
A cover film having a base material layer having a thickness of 45 μm or more and 85 μm or less. The cover film according to claim 1, wherein the surface layer further contains 10 parts by weight or more of trifunctional or less functional (meth) acrylate with respect to 100 parts by weight of the surface layer. The cover film according to claim 1 or 2, wherein the base material layer contains 15 parts by weight or more of the bifunctional or higher functional (meth) acrylate with respect to 100 parts by weight of the base material layer. The cover film according to any one of claims 1 to 3, wherein the base material layer further contains a trifunctional or higher functional (meth) acrylate. A step of laminating a resin composition for a base material layer containing a urethane-based (meth) acrylate and a bifunctional or higher functional (meth) acrylate on a base film.
A step of cross-linking the resin composition for a base material layer so that the cross-linking rate is 90% or less.
A step of laminating a surface layer resin composition containing a tetrafunctional or higher functional (meth) acrylate on the base material layer resin composition,
A step of curing the resin composition for a base material layer and the resin composition for a surface layer to form a cover film having a base material layer and a surface layer.
With
The thickness of the surface layer is 40 μm or more.
The thickness of the substrate layer state, and are more 85μm or less 45 [mu] m,
A method for producing a cover film, wherein the base material layer contains 50 parts by weight or more and 90 parts by weight or less of the urethane-based (meth) acrylate with respect to 100 parts by weight of the base material layer.