TWI515280B - Composition for forming resin layer and flexible display substrate using the same - Google Patents

Description

a composition for forming a resin layer and a flexible display substrate manufactured using the same

The present invention relates to a composition for forming a resin layer, a flexible display substrate produced using the composition, and a method of producing the same.

Recently, in the display method, the use of a conventional cathode ray tube (CRT) display has been converted into a flat panel display such as a plasma display panel (PDP), a liquid crystal display (LCD), an organic light emitting diode (OLED), and analog. In particular, research on flat panel displays has been actively pursued to enable them to be implemented as flexible displays in the future.

At the same time, plastic substrates are the main materials necessary for realizing plastic flat panel displays or next-generation displays, and the demand for plastic substrates is generated according to the development of the flexible display industry. Comparing the physical properties of the plastic substrate used to implement the flexible display with the physical properties of the conventional glass substrate, the plastic substrate serves as the main feature of the flexible display, such as weight, formability, non-breakability, design, The roll-to-roll processability and its similar properties are excellent. However, in order to use an optical plastic film as a plastic substrate, it is required to improve the physical properties of the plastic substrate which are inferior to the physical properties of the glass substrate, such as chemical resistance, thermal characteristics, air barrier properties, and the like.

For this purpose, a method of impregnating a glass fiber sheet with a resin is proposed. However, when a conventional film impregnated only with an acrylic resin or an epoxy resin is used, there is a problem in that it is difficult to apply the film to a high-temperature process because it has poor heat resistance; and it is difficult to apply the film to it. The substrate of a flexible display because it is fragile.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a composition for forming a resin layer comprising a ruthenium-based binder and an acrylic monomer or epoxy resin; A heat-resistant flexible display substrate produced by using the composition; and a method of manufacturing the flexible display substrate.

In order to achieve the above object, an aspect of the present invention provides a composition for forming a resin layer, comprising: a ruthenium-based adhesive having a structure of the following formula; at least one selected from the group consisting of an acrylic monomer and an epoxy resin Compound; and initiator:

Wherein R ₁ to R ₄ are the same or different from each other, and are each independently a C ₁ to C ₁₂ alkyl group, a C ₂ to C ₁₂ allyl group, a C ₂ to C ₁₂ aralkyl group or a C ₂ to C ₁₂ alkenyl group. R ₅ and R ₆ are the same or different from each other, and are each independently hydrogen or vinyl; and S is an integer of from 2 to 1,000.

Here, the mixing ratio of the ruthenium-based binder to the compound may be from 7:3 to 1:9 by weight.

Further, the composition may further include: 9.5 to 70% by weight of a ruthenium-based binder; 30 to 90% by weight of at least one compound selected from the group consisting of acrylic monomers and epoxy resins; and 0.5 to 20% by weight of an initiator.

Further, the acrylic monomer may be at least one selected from the group consisting of bisphenol A ethylene oxide diacrylate, bisphenol A ethylene oxide dimethacrylate, bisphenol A ethoxylate diacrylate, double Phenol A ethoxylate dimethacrylate, bisphenol A polyethoxylate diacrylate, bisphenol A diacrylate, bisphenol S diacrylate, dicyclopentadienyl diacrylate, neopentyl Tetraol triacrylate, ginseng (2-hydroxyethyl) isocyanurate triacrylate, neopentyl alcohol tetraacrylate, bisphenol A dimethacrylate, bisphenol S dimethacrylate, two Cyclopentadienyl dimethacrylate, neopentyl alcohol trimethacrylate, cis (2-hydroxyethyl) isocyanurate trimethacrylate, and neopentyl alcohol tetramethacrylate.

Further, the epoxy resin may be at least one selected from the group consisting of a glycidyl epoxy resin and an alicyclic epoxy resin.

Further, the composition may further include a surfactant.

Further, the composition may further include a solvent.

Another aspect of the present invention provides a flexible display substrate comprising a glass fiber sheet impregnated with a composition.

Another aspect of the present invention provides a flexible display base for manufacturing a glass fiber sheet and a resin layer formed on both sides of the glass fiber sheet A method of a board comprising the steps of: impregnating a glass fiber sheet with a composition for a resin layer as recited in claim 1; and UV-curing the glass fiber sheet impregnated with the composition to UV-curing the glass fiber sheet.

The method may include the steps of: impregnating a glass fiber sheet with a composition for a resin layer; laminating a release film on both sides of the glass fiber sheet impregnated with the composition; and irradiating the glass fiber sheet laminated with the release film by UV irradiation The glass fiber sheet is cured by UV; and the release film is separated from the UV-cured glass fiber sheet.

The method may further comprise the step of heating the UV-cured glass fiber sheet to 200 to 300 ° C after the step of UV curing the glass fiber sheet to thermally cure the glass fiber sheet.

Description of the preferred embodiment

Hereinafter, the present invention will be described in detail.

The present invention provides a composition for forming a resin layer, comprising: a ruthenium-based adhesive having a structure of the following formula 1; at least one compound selected from the group consisting of an acrylic monomer and an epoxy resin; and an initiator:

Wherein R ₁ to R ₄ are the same or different from each other, and are each independently a C ₁ to C ₁₂ alkyl group, a C ₂ to C ₁₂ allyl group, a C ₂ to C ₁₂ aralkyl group or a C ₂ to C ₁₂ alkenyl group. R ₅ and R ₆ are the same or different from each other, and are each independently hydrogen or vinyl; and S is an integer of from 2 to 1,000.

In the composition for forming the resin layer, the acrylic monomer may be a bifunctional or two or more functional acrylic or methacrylic compound. In this case, the acrylic monomer may be at least one selected from the group consisting of bisphenol A ethylene oxide diacrylate, bisphenol A ethylene oxide dimethacrylate, bisphenol A ethoxylate diacrylate Ester, bisphenol A ethoxylate dimethacrylate, bisphenol A polyethoxylate diacrylate, bisphenol A diacrylate, bisphenol S diacrylate, dicyclopentadienyl diacrylate , neopentyl alcohol triacrylate, ginseng (2-hydroxyethyl) isocyanurate triacrylate, neopentyl alcohol tetraacrylate, bisphenol A dimethacrylate, bisphenol S dimethacrylate Ester, dicyclopentadienyl dimethacrylate, pentaerythritol trimethacrylate, ginseng (2-hydroxyethyl) isocyanurate trimethacrylate and pentaerythritol tetramethyl Acrylate.

In the composition for forming a resin layer, the epoxy resin is referred to as a resin having at least one epoxy group. For example, the epoxy group may be a glycidyl epoxy resin or an alicyclic epoxy resin.

The glycidyl epoxy resin may be bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, naphthalene type epoxy resin or hydrogenated compound thereof; epoxy resin having a dicyclopentadiene skeleton An epoxy resin having a triglycidyl isocyanurate skeleton; an epoxy resin having a shaft skeleton; or an epoxy resin having a polyoxyalkylene skeleton.

The alicyclic epoxy resin may be 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 1,2,8,9-diepoxylimene, Epoxy-caprolactone having an ester bond with 3,4-epoxycyclohexylmethanol and 3,4-epoxycyclohexanecarboxylic acid at both ends, or an epoxy resin having a hydrogenated bisphenol A skeleton.

In the composition for forming the resin layer, the mixing ratio of the cerium-based binder to the compound may be from 7:3 to 1:9 by weight. It is preferred to use a ruthenium-based adhesive having high flexibility and heat resistance alone. However, the composition comprising only the ruthenium-based resin cannot be applied to a roll-to-roll process for attaching a release film which is not resistant to temperatures of 150 ° C or more to the sides of the glass fiber sheet impregnated with the composition and The glass fiber sheet coated with the release film is cured because its heat curing temperature is 150 ° C or more. Therefore, when the ruthenium-based adhesive is mixed with an acrylic monomer or an epoxy resin and then used, the release film is attached to both sides of the glass fiber sheet impregnated with the composition, and the photocurable glass fiber sheet is removed from the glass fiber sheet. The film is removed from the film and then the glass fiber sheet is thermally cured. In the case of appropriately adjusting the composition ratio of the ruthenium-based adhesive to the acrylic monomer or the epoxy resin, during the roll-to-roll process, when the release film is removed before the heat curing after photocuring, the release film may be The roller moves smoothly without sticking. Therefore, when the mixing ratio of the ruthenium-based binder to the compound exceeds 7:3, the release film cannot smoothly move along the roller during the roll-to-roll process, when the release film is removed before the heat curing after photocuring. Not sticky. On the contrary, when the mixing ratio of the compound to the ruthenium-based binder is not up to 1:9, the content of the ruthenium-based binder in the composition is extremely low and thus the improvement effect of flexibility and heat resistance cannot be expected.

The composition for forming a resin layer of the present invention may further include an initiator for curing the above-mentioned sulfhydryl-based binder and compound. The initiator may be a photopolymerization initiator or a thermal polymerization initiator.

In the present invention, a photopolymerization initiator is referred to as causing decomposition or bonding using lithographic exposure and producing an active material (such as a radical, an anion, a cation or the like capable of initiating polymerization of a ruthenium-based binder with an acrylic monomer or an epoxy resin. Compound). Examples of the photopolymerization initiator may include an acetophenone compound such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)one, α-hydroxy-α, α'-dimethyl Acetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinylpropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether and alanyl methyl An ether; an α-keto alcohol compound such as 2-methyl-2-hydroxypropiophenone; a ketal compound such as benzyldimethylketal; an aromatic sulfonium chloride compound such as 2-naphthalenesulfonium chloride; An active hydrazine compound such as 1-phenyl ketone-1,1-propanedione-2-(o-ethoxycarbonyl) hydrazine; a diphenyl ketone compound such as diphenyl ketone, benzhydryl benzoic acid, 3 , 3'-dimethyl-4-methoxydiphenyl ketone and 3,3',4,4'-tetrakis(t-butylperoxycarbonyl)diphenyl ketone; diphenyl (2,4 , 6-trimethylbenzimidylphosphine oxide; and methyl benzoylcarbamate.

Examples of the thermal polymerization initiator may include: an organic peroxide such as benzammonium peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, and peroxidation Di-n-propyl carbonate, di(2-ethoxyethyl)dicarbonate, tert-butyl peroxy neodecanoate, tert-butyl peroxybutyrate, (3,5,5-trimethyl Radical, dipropyl Mercapto peroxide and diethyl hydrazine peroxide; and azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile, 1, 1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis (2,4- Dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid Ester), 2,2'-azobis(2-hydroxymethylpropionitrile) and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

The composition for forming the resin layer may include 9.5 to 70% by weight of a ruthenium-based binder; 30 to 90% by weight of at least one compound selected from the group consisting of acrylic monomers and epoxy resins; and 0.5 to 20% by weight of an initiator. When the content of the ruthenium-based binder, the compound, and the initiator in the composition deviate from the above range, the heat resistance, thermal expansion property, and flame retardancy of the composition may be deteriorated.

In the present invention, the composition for forming the resin layer may further include a surfactant and a solvent, as necessary, for the purpose of achieving a specific function.

The surfactant is effective to modify the surface of the resin layer, and preferably may be a sulfhydryl surfactant or a fluorine-based surfactant. The sulfhydryl surfactant can include a sulfonium group and an ionic group. The ionic group can be an anionic group. Specific examples of the anionic group may include a carboxylate, a sulfonate, a phosphonate, and the like.

In order to convert the surfactant into fumes during UV curing or heat curing during the manufacture of the flexible display substrate, it is preferred that the surfactant has a solid content of 80 to 100% by weight (based on the total amount of 100% by weight) and has The flash point is 100 ° C or above.

Further, it is preferred that the surfactant is included in an amount of 0.005 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the solid content of the composition for forming the resin layer. When the surfactant is less than 0.005 When the amount by weight is included, the effect of the surface of the modified resin layer may be insufficient, and when the surfactant is included in an amount of more than 5 parts by weight, the heat resistance of the resin layer may be deteriorated.

The solvent may be selected from the group consisting of ketones, ethers, esters, alcohols, hydrocarbons, acetonitrile, nitromethane, water, and mixtures thereof. Examples of the solvent may include: a ketone such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like; an ether such as tetrahydrofuran, 1,4-dioxane, 1,2-di Methoxyethane and its analogues; esters such as ethyl acetate, ethoxyethyl acetate and the like; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2 -butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-butoxyethanol and Analogs; hydrocarbons such as n-hexane, n-heptane, isooctane, benzene, toluene, xylene, gasoline, diesel, kerosene and the like; acetonitrile; nitromethane; and water. These solvents may be used singly or in the form of a mixture of two or more thereof.

The method of manufacturing a flexible display substrate may include the steps of: impregnating a glass fiber sheet with a composition for a resin layer; and UV-curing the glass fiber sheet impregnated with the composition to UV-curce the glass fiber sheet.

In the step of UV-curing the glass fiber sheet, the intensity of the UV irradiation may vary depending on the kind of the component included in the composition for forming the resin layer and the amount of the photopolymerization initiator. Further, it is preferred that the release film is laminated on both sides of the glass fiber sheet impregnated with the composition before the step of UV curing the glass fiber sheet, and the release film is removed from the glass fiber sheet after the step of UV curing the glass fiber sheet Separated on both sides. When the laminate is detached from the film, the temperature and pressure of the laminator can be adjusted according to the purpose of the present invention. whole. Therefore, when the glass fiber sheet is laminated with a release film and then UV-cured, it is easy to uniformly control the final thickness of the resin layer formed after the UV irradiation.

Additionally, the method may further comprise the step of heating the UV-cured glass fiber sheet to thermally cure the glass fiber sheet after the step of UV curing the glass fiber sheet, depending on the type of composition applied to the glass fiber sheet. In this case, the heat curing temperature may be 200 to 300 ° C, and the heat curing time may be appropriately adjusted in consideration of the kind of the composition and the heat curing temperature. Therefore, in the step of thermal curing, the glass fiber sheet having insufficient UV curing formed in the step of UV curing is further thermally cured to sufficiently cure the glass fiber sheet, thereby improving the heat resistance of the substrate as the final product.

The flexible substrate may include a glass fiber sheet impregnated with a composition for forming a resin layer.

The flexible display substrate is manufactured by the above method, and it may have a thickness of 10 to 200 μm.

The flexible display substrate is characterized in that it has excellent flexibility and heat resistance. For example, the flexible display substrate may have a coefficient of thermal expansion of 10 ppm/° C. or less, or 10 ppm/° C. or less.

Hereinafter, the present invention will be described in more detail with reference to the following examples, comparative examples, and experimental examples. However, the examples are set forth to illustrate the invention, and the scope of the invention is not limited thereto.

Example 1

Mix 20 wt% bisphenol A ethylene oxide diacrylate (manufacturer: Miwon Chemical, Ltd., product name: Miramer M240), 30 wt% bisphenol A ethylene oxide dimethacrylate (manufacturer: KYOEISHA Corp., product name :BP-4EM) and 50% by weight of a sulfhydryl binder having the structure of the above formula 1 (R ₁ to R ₃ : methyl group, R ₄ : phenyl group, R ₅ to R ₆ : vinyl group, S: 10) to obtain the first a mixture. Next, 2 wt% of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184, manufactured by BASF Corporation) and 2 wt% of benzamidine peroxide were added to the first mixture to obtain a second amount, based on the amount of the first mixture. mixture. Next, the second mixture was stirred for 1 hour to prepare a composition for forming a resin layer.

A glass fiber sheet having a thickness of 40 to 60 μm was impregnated with a composition for forming a resin layer at room temperature for 1 hour. Thereafter, a release film was laminated on both sides of the glass fiber sheet impregnated with the composition using a laminator, and then the glass fiber sheet laminated with the release film was subjected to UV curing using a UV exposure machine. Subsequently, the release film is removed from both sides of the UV-cured glass fiber sheet, and then the glass fiber sheet is thermally cured, thereby finally obtaining the substrate.

Example 2

Mixing 50 wt% of 3,4-epoxycyclohexylmethyl-3, 10 wt% of bisphenol A ethylene oxide dimethacrylate and 40 wt% of the structure of formula 1 above (R ₁ to R ₃ : methyl, R ₄ : A ruthenium-based binder of phenyl, R ₅ to R ₆ :vinyl, S: 10) to obtain a first mixture. Next, 2 wt% of benzamidine peroxide was added to the first mixture in an amount of the first mixture to obtain a second mixture. Next, the second mixture was stirred for 1 hour to prepare a composition for forming a resin layer.

Impregnated with a composition for forming a resin layer at room temperature Glass fiber sheets of 40 to 60 μm for 1 hour. Thereafter, a release film was laminated on both sides of the glass fiber sheet impregnated with the composition using a laminator, and then the glass fiber sheet laminated with the release film was subjected to UV curing using a UV exposure machine. Subsequently, the release film is removed from both sides of the UV-cured glass fiber sheet, and then the glass fiber sheet is thermally cured, thereby finally obtaining the substrate.

Comparative example 1

Unlike the compositions for forming a resin layer of Examples 1 and 2, first mixing 25 wt% bisphenol A ethoxylated diacrylate, 15 wt% ethoxylated bisphenol fluorene diacrylate (manufacturer: Hannong Chemical Co .,Ltd.,Product Name:BPF-022), 50% by weight of ethoxylated pentaerythritol tetraacrylate (manufacturer: Hannong Chemical Co., Ltd., product name: PE-044) and 10% by weight with two A valence functional group of hydrazine acrylate (manufacturer: Miwon Chemical Co., Ltd., product name: HR-6082) to obtain a mixture. Next, 2 wt% of 1-hydroxycyclohexyl phenyl ketone was added to the mixture in an amount of the mixture, and stirred for 1 hour to prepare an impregnation solution. Thereafter, the impregnation solution was treated in the same manner as in Example 1, whereby the substrate was finally obtained.

Experimental example

With respect to the substrates of Examples 1 and 2 and Comparative Example 1, the CTE (thermal expansion coefficient), TGA (thermogravimetric analysis), and surface characteristics after heat treatment were evaluated, and the results are shown in Table 1 below.

<CTE measurement method>

First, the substrates of Examples 1 and 2 and Comparative Example 1 were heated from room temperature to 330 ° C at a heating rate of 10 ° C/min under a N ₂ atmosphere of a thermomechanical analyzer (TMA) at a cooling rate of 5 ° C/min. It was cooled to room temperature at 330 ° C, and then heated a second time from room temperature to 330 ° C at a heating rate of 10 ° C / min. At the second heating of the substrate, the CTE of these substrates was measured from room temperature to 330 ° C at intervals of 50 ° C, and then the average value was calculated.

<TGA analysis method>

The substrates of Examples 1 and 2 and Comparative Example 1 were each heated from room temperature to 150 ° C at a heating rate of 10 ° C/min under a N ₂ atmosphere of a thermogravimetric analyzer (TGA), and then maintained at 150 ° C for 10 minutes. . The substrates were then heated from 150 ° C to 300 ° C at a heating rate of 10 ° C/min, and then maintained at 300 ° C for 1 hour and 10 minutes. The weight loss (%) which had been produced from 1 minute to 62 minutes after it reached 300 ° C was measured.

<Surface feature evaluation method>

The substrates of Examples 1 and 2 and Comparative Example 1 were evaluated by measuring the surface roughness of each substrate having an area of 1 mm × 1 mm before and after heat treatment (250 ° C / 10 min) using a 10 × magnifying lens as a 3D profiler. ΔRa (roughness).

As shown in Table 1 above, it can be confirmed that the substrate of Comparative Example 1 has a CTE of 14 ppm/° C. or less and 14 ppm/° C., and the CTE of Example 1 is 7 ppm/° C. Or 7 ppm/° C. or less and the CTE of Example 2 is 9 ppm/° C. or less and 9 ppm/° C., and the weight loss of the substrate of Comparative Example 1 is 1.5% or less, and the weight loss of Example 1 is 1.0% or less. And the weight loss of Example 2 was 1.2% or less. Further, it was confirmed that the ΔRa of the substrate of Comparative Example 1 was 600 nm or less, and the ΔRa of Example 1 was 100 nm or less and the ΔRa of Example 2 was 200 nm or less.

Although the preferred embodiment of the present invention has been disclosed, it will be understood by those skilled in the art that various modifications, additions and substitutions may be made without departing from the scope and spirit of the invention as disclosed in the appended claims. possible.

Favorable effect

When a flexible display substrate is produced using the composition for forming a resin layer of the present invention, the flexible display substrate has excellent formability, is transparent and flexible, and has excellent thermal expansion property, excellent heat resistance, and Excellent flame retardancy. Therefore, the flexible display substrate can replace the conventional glass substrate.

Although the preferred embodiment of the present invention has been disclosed, it will be understood by those skilled in the art that various modifications, additions and substitutions may be made without departing from the scope and spirit of the invention as disclosed in the appended claims. possible.

Claims (9)

A composition for forming a resin layer, comprising: a ruthenium-based adhesive having a structure of the following formula 1; at least one compound selected from the group consisting of an acrylic monomer and an epoxy resin; and an initiator, wherein the acrylic monomer It is at least one selected from the group consisting of bisphenol A ethylene oxide diacrylate, bisphenol A ethylene oxide dimethacrylate, bisphenol A ethoxylate diacrylate, bisphenol A ethoxylate Dimethacrylate, bisphenol A polyethoxylate diacrylate, bisphenol A diacrylate, bisphenol S diacrylate, dicyclopentadienyl diacrylate, neopentyl alcohol triacrylate, Reference (2-hydroxyethyl) isocyanurate triacrylate, neopentyl alcohol tetraacrylate, bisphenol A dimethacrylate, bisphenol S dimethacrylate, dicyclopentadienyl Methacrylate, pentaerythritol trimethacrylate, ginseng (2-hydroxyethyl) isocyanurate trimethacrylate and pentaerythritol tetramethacrylate, wherein the epoxy resin is Selecting a group of free glycidyl epoxy resins and alicyclic epoxy resins One: [Formula 1] Wherein R ₁ to R ₄ are the same or different from each other, and are each independently a C ₁ to C ₁₂ alkyl group, a C ₂ to C ₁₂ allyl group, a C ₂ to C ₁₂ aralkyl group or a C ₂ to C ₁₂ alkenyl group. R ₅ and R ₆ are the same or different from each other, and are each independently hydrogen or vinyl, and S is an integer of from 2 to 1,000. The composition of claim 1, wherein the mixing ratio of the cerium-based binder to the compound is from 7:3 to 1:9 by weight. The composition according to claim 1, which comprises: 9.5 to 70% by weight of the ruthenium-based binder; 30 to 90% by weight of the at least one compound selected from the group consisting of acrylic monomers and epoxy resins; and 0.5 to 20% by weight The initiator. The composition of claim 1, which further comprises a surfactant. The composition of claim 1, which further comprises a solvent, wherein the solvent is selected from the group consisting of a ketone, an ether, an ester, an alcohol, a hydrocarbon, acetonitrile, nitromethane, water, and a mixture thereof. A flexible display substrate comprising a glass fiber sheet impregnated with the composition as recited in claim 1. A method of producing a flexible display substrate comprising a glass fiber sheet and a resin layer formed on both sides of the glass fiber sheet, comprising the steps of: using the composition for forming a resin layer as recited in claim 1 The glass fiber sheet is impregnated; and the glass fiber sheet impregnated with the composition is UV-cured to cure the glass fiber sheet by UV. The method of claim 7, comprising the steps of: impregnating a glass fiber sheet with a composition for forming a resin layer as recited in claim 1; on both sides of the glass fiber sheet impregnated with the composition Lamination of the release film; UV irradiation of the glass fiber sheet laminated with the release film to UV cure the glass fiber sheet; and separating the release film from the UV-cured glass fiber sheet. The method of claim 7, further comprising the step of heating the UV-cured glass fiber sheet to 200 to 300 ° C after the step of UV curing the glass fiber sheet to thermally cure the glass fiber sheet.