JPS63312309A - Liquid curable resin composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid curable resin composition, and particularly to a liquid curable resin composition suitable as a coating material for optical fibers.

[Conventional technology]

In the production of optical fibers, a resin coating is applied immediately after hot melt spinning of glass fibers for the purpose of protection and reinforcement.

As this resin coating, a structure in which a flexible primary coating layer is first provided on the surface of the optical fiber and a more rigid secondary coating layer is provided on the outside thereof is well known.

The material for this primary coating layer is polyester (meth).
Various liquid curable resin compositions containing acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, etc. as main components are known.

[Problem that the invention seeks to solve]

Incidentally, since optical fibers are used in various environments, they are required to have small transmission loss even at, for example, about -40°C. Generally, if the flexibility of the optical fiber coating material is impaired, the transmission loss increases, so the primary coating layer of the optical fiber is required to have a small Young's modulus and be flexible even at a low temperature of about -40°C. On the other hand, since the optical fiber coating material protects and reinforces the glass fiber, the primary coating layer is also required to have high adhesion to the glass fiber.

However, conventional materials for the primary coating layer, including those described above, generally have a problem in that increasing the adhesion to the optical fiber increases the Young's modulus at low temperatures.

Therefore, an object of the present invention is to have excellent adhesion to optical fibers when used as a coating material for optical fibers,
Moreover, it is an object of the present invention to provide a liquid curable resin composition whose cured product has a Young's modulus of 5 kg/mu 2 or less even at a low temperature of about -40°C.

[Means for solving problems]

The present invention solves the above-mentioned problems.
65 to 90% by weight of polyurecne having a polyoxyalkylene structure composed of two or more types of oxyalkylene groups having 2 to 6 carbon atoms and an ethylenically unsaturated group (bl) Ethylenically unsaturated group having at least one amino group in the molecule Saturated monomer 2 to 20% by weight (c1 General formula (I): [In the formula, R7 is a hydrogen atom or a methyl group, R2 is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R3 is a carbon number of 2 to 6 2 to 20% by weight of (meth)acrylate (d+ polymerization initiator 0.1 to 10% by weight), where n is an average value of 1 to 2.
A liquid curable resin composition comprising:

It provides:

The ia+al polyurethane (hereinafter referred to as "polymer (a)") used in the liquid curable resin composition (hereinafter referred to as "composition") of the present invention has an oxyalkylene group of 2 to 6 carbon atoms. It is obtained by reacting a diol having a polyoxyalkylene structure (hereinafter referred to as "specific polyoxyalkylene structure") composed of at least one species, a compound having an ethylenically unsaturated group, and a diisocyanate.

Below, the method for producing the following polymer (al) will be exemplified.

[Production method 1] A method in which a compound having an ethylenically unsaturated group is reacted with a functional group of a polymer obtained by reacting a diol having a specific polyoxyalkylene structure with a diisocyanate.

[Production method 2] A method in which a diol having a specific polyoxyalkylene structure is reacted with a functional group of an adduct obtained by reacting a diisocyanate with a compound having an ethylenically unsaturated group.

[Production method 3] A method of simultaneously reacting a diisocyanate, a diol having a specific polyoxyalkylene structure, and a compound having an ethylenically unsaturated group.

Diols having a specific polyoxyalkylene structure used in the above method include, for example, ethylene oxide, propylene oxide, tetrahydrofuran, oxetane,
It is obtained by ring-opening copolymerization of at least two compounds selected from substituted oxetane, tetrahydropyran, and oxepane.

Among these diols having a specific polyoxyalkylene structure, diols having a poly(oxypropylene-oxytetramethylene) structure obtained by copolymerizing propylene oxide and tetrahydrofuran at a weight ratio of 60:40 to 5:95, For example, polyoxypropylene polyoxytetramethylene glycol (hereinafter referred to as
r PPTG J) is particularly preferred. In this case, the weight ratio of propylene oxide and tetrahydrofuran (propylene oxide/tetrahydrofuran) is 60/
If it exceeds 40, the heat resistance of the composition after curing will deteriorate.

In addition, the weight ratio of propylene oxide and tetrahydrofuran (propylene oxide/tetrahydrofuran) is 5/
When it is smaller than 9, the viscosity of the composition becomes high.

Diols used in the production of polymers (al) include diols having the above-mentioned specific polyoxyalkylene structure, polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, and sebacic acid. A polyester diol obtained by reacting a polyester diol with a diol having the above-mentioned specific polyoxyalkylene structure and ε-
Examples include polycaprolactone diol obtained by reacting with caprolactone.

The diol having the above specific polyoxyalkylene structure is, for example, Unisafe DC1100 (manufactured by NOF),
Unisafe 1800 (same), Unisafe DCB 110
0 (same), Unisafe DC81800 (same), PPT
G 4000 (Odogaya Chemical), PPTG 200
0 (same) and PPTG 1000 (same).

These polymers (81) may be used alone or in combination of two or more.

These diols having a specific polyoxyalkylene structure can be used in combination with a diol and/or diamine that does not have a specific polyoxyalkylene structure to the extent that the effects of the present invention are not lost.

Examples of diols that do not have a specific polyoxyalkylene structure include polyether diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, and polytetramethylene Polyhydric alcohols such as glycol, 116-hexanediol, neopentyl glycol, 1,4-cyclohexane dimetatool and polyhydric alcohols such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, and sebacic acid. Polyester diol obtained by reacting with a basic acid; liquid polybutadiene having two hydroxyl groups in one molecule or a hydrogenated product of this compound; ε-caprolactone and ethylene glycol, polyethylene glycol, polypropylene glycol, tetramethylene glycol, polyester diol; 2 such as tetramethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexane dimetatool, 1,4-butanediol, etc.
polycaprolactone diol prepared by reacting diols of different values: DN-981 (same), DN-98
2 (same), DN-983 (same), PC-800
Examples include polycarbonate diols represented by trade names such as 0 (PPG Company, USA).

Even if these diols and diamines that do not have a specific polyoxyalkylene structure are used alone,
Two or more types may be used in combination.

Examples of the above diamine include ethylene diamine, tetramethylene diamine, hexamethylene diamine,
Examples include diamines such as phenylene diamine and 4,41-diaminodiphenylmethane; diamines containing heteroatoms; and polyether diamines.

As the diisocyanate compound, 2.4-) luene diisocyanate, 2.6-) luene diisocyanate,
1,3-xylene diisocyanate, 1.

4-xylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p
-phenylene diisocyanate, 3,3'-dimethyl-
4.4'-diphenylmethane diisocyanate, 4.4
'-Diphenylmethane diisocyanate, 3,3'-dithymelphenylene diisocyanate, 4,4'-biphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylene bis(
4-cyclohexyl isocyanate) and the like.

These diisocyanates may be used alone or in combination of two or more.

Furthermore, as a compound having an ethylenically unsaturated group,
For example, (meth)acrylic compounds having a hydroxyl group, an acid halide group, or an epoxy group can be mentioned.

Examples of (meth)acrylic compounds having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-
Hydroxypropyl (meth)acrylate, 2-hydroxyoctyl (meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin di(meth)acrylate, dipentaerythry[·-monohydroxypenta(meth)acrylate, 1,4-butanediol mono (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, ■, 6-hexanediol mono (meth)acrylate, neopentyl glycol mono (meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylol Compounds obtained by the addition reaction of glycidyl group-containing compounds such as ethanedi(meth)acrylate, alkyl glycidyl ether, aryl glycidyl ether, glycidyl (meth)acrylate and (meth)acrylic acid, and compounds represented by the following structural formula ( Mention may be made of meth)acrylates.

R.

CI(22CCOC1(2CH2i0CC1hC1lz
CHzCKzC1(zhot ((in the formula, R5 is a hydrogen atom or a methyl group, and n is 1 to 5) Examples of (meth)acrylic compounds having an epoxy group include glycidylnistyl (meth)acrylic acid, etc. Can be mentioned.

Examples of the (meth)acrylic compound having an acid halide group include (meth)acrylic halides such as (meth)acrylic chloride and (meth)acrylic bromide. These compounds having an ethylenically unsaturated group may be used alone or in combination of two or more.

Next, a preferred embodiment of the above production method 1 will be shown.

The amount of diisocyanate used per equivalent of hydroxyl group of diol having a specific polyoxyalkylene structure is approximately 0.
．． It is 5 to 2 moles. In this reaction, a catalyst such as copper naphthenate, cobalt naphthenate, zinc naphthenate, n-butyltin laurate, or triethylamine is usually used in an amount of 0.01 to 1.0 parts by weight per 100 parts by weight of the total amount of reactants. Perform the reaction. The reaction temperature in this reaction is usually 0 to 80°C.

A compound having an ethylenically unsaturated group is reacted with the functional group of the intermediate product thus obtained, and the amount of the compound having an ethylenically unsaturated group used is 1 equivalent of the functional group of the intermediate product. The reaction conditions are similar to those for producing the intermediate product described above.

Next, a preferred embodiment of the above production method 2 will be shown.

A compound having a specific polyoxyalkylene structure per equivalent of functional group of an intermediate product obtained by reacting about 1 mole of a compound having an ethylenically unsaturated group with 1 mole of diisocyanate under the same reaction conditions as in Production Method 1. The diol is used so that the amount of hydroxyl group is about 1 equivalent, and the reaction is carried out under the same reaction conditions as in Production Method 1.

Next, a preferred embodiment of the above production method 3 will be shown.

Production method 1: 0.5 to 2 mol of diisocyanate and 0.5 to 2 mol of a compound having an ethylenically unsaturated group are added to 1 mol of diol having a specific polyoxyalkylene structure.
React under the same reaction conditions.

When carrying out the above production methods 1 to 3, add a polyol other than trifunctional to a diol, a polyamine other than trifunctional to a diamine, or a polyisocyanate other than trifunctional to a diisocyanate to the extent that the bioacid does not gel. It can be used in combination, and the amount used is usually 5 parts by weight per 100 parts by weight of diol, diamine or diisocyanate.
~30 parts by weight. Examples of polyols other than trifunctional include, for example, addition products of glycerin and propylene oxide, glycerin, 1,2,3-pentanetriol, 1,2,3-butanetriol, tri(2
-hydroxypolyoxyprobyl) polysiloxane, polycaprolactone triol, polycaprolactone tetraol, liquid polybutadiene having more than two hydroxyl groups in one molecule, or a hydrogenated product of this compound. Examples of non-trifunctional polyamines include diethylenetriamine, R2,3-)riaminopropane, polyoxypropyleneamine, etc., and non-trifunctional polyisocyanate compounds include:
Examples include polymethylene polyphenylisocyanate, triphenylmethane 4.4',4''-triisocyanate, and the like.

In the present invention, the ratio of a specific polyoxyalkylene structure to the total amount of polymer (al) is usually 50 to 95
The proportion of ethylenically unsaturated groups is usually 0.5 to 10% by weight, preferably 1 to 8% by weight.

Further, the polymer (a) usually has a number average molecular weight of 300.
It is 0 to 10,000, preferably 3,500 to 8,000. When this number average molecular weight is less than 3000, the Young's modulus at low temperatures of the obtained cured product increases, and 1
If it exceeds 0,000, the viscosity of the composition will reach an upper limit and the coating properties for optical fibers will deteriorate. Further, the proportion of the polymer fa+ in the composition needs to be 65 to 90% by weight, and preferably 70 to 85% by weight.

If the proportion in this composition is less than 65%,
The Young's modulus of the cured product at low temperatures increases, and if the weight exceeds 90 weight single cylinders, the coatability for optical fibers decreases.

Examples of ethylenically unsaturated monomers having at least one amino group in the molecule of the bl component used in the composition of the present invention include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N,N- Examples include monoethylenically unsaturated monomers having a tertiary amino group such as dimethylacrylamide, N,N-dimethylaminopropylacrylamide, octylacrylamide, N,N-dimethylaminoethyl acrylate, and N,N-dimethylaminoethyl acrylate. Among these, N-vinylpyrrolidone, N
-Vinyl caprolactam, acryloylmorpholine,
It is preferable because it is relatively less irritating to human skin.

Ethylenically unsaturated monomers having a small number of amino groups (one in each molecule) may be used singly, or two
More than one species may be used in combination.

(The proportion of the BL component in the composition is 2 to 20% by weight.
The content is preferably 3 to 12% by weight. If the proportion of this fbl component is less than 2% by weight, the adhesiveness of the resulting cured product to optical fibers will decrease, and if it exceeds 20% by weight, the water absorption rate of the cured product will increase.

In the general formula (I) representing the (meth)acrylate of component (c) used in the composition of the present invention, the alkyl group having 1 to 12 carbon atoms represented by R2 is, for example, a methyl group, an ethyl group, a propyl group. , a hexyl group, a nonyl group, etc., preferably a hydrogen atom, a methyl group, an ethyl group, etc., and examples of the alkylene group having 2 to 6 carbon atoms represented by R3 include a methylene group, an ethylene group, a propylene group, and a tetramethylene group. group, butylene group, pentamethylene group, hexamethylene group, etc. Moreover, when n exceeds 2 in general formula (I), the adhesiveness of the obtained cured product to the optical fiber decreases.

(The (meth)acrylate represented by the general formula (I) as the c1 component includes phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypropyl (meth)acrylate, etc., and the commercially available product is Aroex MIOL. (manufactured by Toagosei@Rumor), Aronixt 111 (manufactured by Toagosei ■), etc.

Among these (c+ acid components), phenoxyethyl acrylate is preferred.

The proportion of component (c) in the composition is 2 to 20% by weight.
The content is preferably 3 to 12% by weight. If the proportion of this (c1 component) is less than 2% by weight, the curing speed of the composition will be slow, and if it exceeds 20% by weight, the Young's modulus of the cured product at low temperatures will increase.

The photopolymerization initiator that can be used as fd) component used in the composition of the present invention is not particularly limited, and examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, acetophenone, and benzophenone. , xanthone, fluorenone, henzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-
Chlorhensiphenone, 414'-dimethoxyhensiphenone, 4,4'-diaminobenzophenone, Michler's ketone, hendiin propyl ether, hendiin ethyl ether, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy- 2-methylpropan-1-one, 2-human 0x-2-methyl-1-
Examples include phenylpropan-1-one, thioxanthone compounds, 2-methyl-1-(4-(methylthio)phenyl-2-morpholino-propan-1-one, 2.4.6-trimethylbenzoyldiphenylphosphine oxide, etc.) It will be done.

The thermal polymerization initiator that can be used as the dl component in the composition of the present invention is also not particularly limited, and various types can be used, such as peroxides and azo compounds. For example, benzoyl peroxide,
Examples include t-butyl peroxyhenzoate and azobisisobutyronitrile.

These polymerization initiators may be used alone or in combination of two
More than one species may be used in combination, and when a photopolymerization initiator is used, a sensitizer (photopolymerization accelerator) such as an amine compound may be used in combination as necessary.

(The proportion of the DL component in the composition needs to be 0.1 to 10% by weight, preferably 2 to 5% by weight.The proportion of the FDL component in the composition is less than 0.1% by weight. If so, the curing speed of the composition will be slow, and if it exceeds 10% by weight, the storage stability of the composition and the heat resistance and dirty water resistance after curing will decrease.

In the present invention, in addition to the fat to Methoxysilane, γ-(2
-aminoethyl)aminopropyltrimethoxysilane,
γ-methacryloxypropyltriethoxysilane, γ-
The composition may contain glycidoxypropyltriethoxysilane, γ-mercaptopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, T-(2-aminoethyl)aminopropyltriethoxysilane, and the like. The proportion of these silane coupling agents in the composition is usually 0.1 to 5% by weight, and 0.3% by weight.
It is preferably 3% by weight. If the proportion of this silane coupling agent is less than 0.1% by weight, the adhesion of the obtained cured product to optical fibers will decrease when the humidity is high, and if it exceeds 5% by weight, the storage stability of the composition will deteriorate. decreases.

In addition, other additives may be used in the composition of the present invention as necessary, such as reactive diluents other than the components (b) and fc) having ethylenically unsaturated groups, aging An inhibitor, a polymerization inhibitor, a leveling agent, etc. can be added.

Reactive diluents other than components (b) and fe) having ethylenically unsaturated groups can be used within the range that does not adversely affect the curability of the composition of the present invention, the mechanical properties of the obtained cured product, etc. . Such reactive diluents are not particularly limited, and include, for example, 2-hydroxyethyl acrylate, 2-
Hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, butoxyethyl acrylate, ethyl diethylene glycol acrylate, isobornyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dicyclopentadiene acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, methyl triethylene Glycol acrylate, 7-amino-3,7-dimethyloctyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, polypropylene glycol methacrylate, diethylaminoethyl methacrylate, trimethylolpropane triacrylate, ethylene glycol diacrylate, tetraethylene glycol Diacrylate, polyethylene glycol diacrylate, 1.4-butanediol diacrylate, 1.6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane trioxyethyl acrylate, trimethylolpropane trioxyprobyl acrylate, vinyl Examples include phenol, acrylamide, vinyl acetate, vinyl ether, and styrene.

The viscosity of the composition of the present invention prepared in this way is usually 1000 to 20000 cP/25°C, preferably 2000 to 10000 cP/25°C, and the Young's modulus after curing is usually 0.01 ~0.7 kg/vs
2 (temperature 23°C).

In order to apply the composition of the present invention to an optical fiber to form a primary coating layer, for example, immediately after spinning, apply the composition to the surface of the glass fiber as appropriate so that the film thickness after curing is about 10 to 200 μm. After coating by this method, the composition may be cured by irradiation with radiation such as ultraviolet rays or electron beams, or by heating.

When providing a more rigid secondary coating layer on the outside of the flexible primary coating layer obtained in this way, polyamide resin, liquid crystal polyester resin, or general thermosetting type or ultraviolet or electron beam curing materials,
For example, polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, etc. may be applied and cured.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, "parts" in the examples mean parts by weight.

Example 1 In a reaction vessel equipped with a stirrer, 81.46 g of 2.4-)lylene diisocyanate and 1 g of dibutyltin dilaurate were added.
And 1 g of 2,6-di-t-butyl-4-methylphenol, which is a polymerization inhibitor, was charged. This has a number average molecular weight of 3
700 polyoxypropylene polyoxytetramethylene glycol (product name PPTG4000, Hodogaya Chemical ■
864.23 g of the solution (manufactured by Mimaki Co., Ltd.) was added over 2 hours while maintaining the internal temperature at 40 to 50°C.

After the addition was completed, stirring was further continued at 40 to 50°C for 1 hour. Then hydroxyethyl acrylate 54.31
g was added while maintaining the internal temperature at 40 to 50°C, and (a
A polymer (8) having a number average molecular weight of 4300, which is the l component, was obtained.

Next, 8 parts of phenoxyethyl acrylate, 10 parts of N-vinylpyrrolidone, 5 parts of pendyl methyl ketal, and 2 parts of γ-methacryloxypropyltrimethoxysilane were evenly mixed with 75 parts of the above polymer (^) to give 25 parts of the polymer (^). A composition with a viscosity of 7500 cP at °C was obtained.

Example 2 The procedure was the same as in Example 1, except that the amount of phenoxyethyl acrylate used was changed from 8 parts to 13 parts, and the amount of N-vinylpyrrolidone used was changed from 10 parts to 5 parts. A composition having a viscosity of 9500 cP was obtained.

Example 3 The viscosity at 25° C. was 10,000 cP in the same manner as in Example 1, except that 8 parts of Aronisox MIOI (trade name, manufactured by Toagosei Kagaku ■) was used instead of 8 parts of phenoxyethyl acrylate. A composition was obtained.

Example 4 The viscosity at 25°C was 9000 cP in the same manner as in Example 1 except that 10 parts of N-vinylcaprolactam was used instead of 10 parts of N-vinylpyrrolidone in Example 1.
A composition was obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out at 25° C., except that the amount of the polymer (A) used in Example 1 was changed from 75 parts to 60 parts, and the amount of phenoxyethyl acrylate was changed from 8 parts to 23 parts. A composition having a viscosity of 3000 cP was obtained.

Comparative Example 2 In the same manner as in Example 1, except that 8 parts of Aronix M113 (trade name, manufactured by Toagosei Kagaku Co., Ltd.) represented by the formula: was used instead of 8 parts of phenoxyethyl acrylate in Example 1, the procedure was carried out at 25°C. A composition with a viscosity of 14000 cP was obtained.

Test Example For each composition prepared in the above Examples and Comparative Examples,
Adhesion to the substrate and Young's modulus of the cured product were measured using the following methods. The results are shown in Table 1.

Measurement of adhesion (i) After coating the composition on a quartz plate so that the thickness after curing is 0.2 nm, the total irradiation energy was
A cured film was obtained by irradiating ultraviolet rays corresponding to J/cnT using a metal halide lamp.

(b1) Leave the hardened film on the quartz plate in the form of a tape with a width of 1 cm, peel it by pulling one end of the hardened film in a direction perpendicular to the quartz plate, measure the force required for peeling, and measure the average The value was evaluated as the adhesion of the cured film to the quartz plate.

Measurement of Young's Modulus A cured film formed on a quartz plate in the same manner as the adhesion evaluation test was left in the form of a tape with a width of 61 m, and the peeled film was used as a sample, and the distance between marked lines was 25 nm using the tensile test method specified in JIS K6911. The Young's modulus was measured at 23°C and -40"C.

Table 1 [Effects of the Invention] The composition of the present invention is cured by various types of radiation, such as electron beams, ultraviolet rays, visible light, etc., or by heating.

The cured product obtained from the composition of the present invention has excellent adhesion to a base material, such as quartz, and has a small Young's modulus over a wide temperature range, for example, a Young's modulus of 5 kg/mm 2 even at a low temperature of about -40°C. It is extremely excellent as shown below.

Therefore, the composition of the present invention is excellent as a coating material for optical eye bars, and also as a coating material for various base materials.

Claims (1)

Scope of Claims: (a) 65 to 90% by weight of polyurethane having a polyoxyalkylene structure composed of two or more types of oxyalkylene groups having 2 to 6 carbon atoms and an ethylenically unsaturated group (b) In the molecule Ethylenically unsaturated monomer having at least one amino group 2 to 20% by weight (c) General formula (I): ▲Mathematical formula, chemical formula, table, etc.▼(I) [In the formula, R_1 is a carbon atom or a methyl group , R_2 is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R_3
is an alkylene group having 2 to 6 carbon atoms, and n is an average value of 1 to 2] 2 to 20% by weight of (meth)acrylate (d) 0.1 to 10% by weight of a polymerization initiator A liquid curable resin composition containing %.