Thermosetting resin composition for intermediate substrate

Abstract

The present invention provides a thermosetting resin composition for intermediate materials that can produce fiber-reinforced plastics with excellent heat resistance and mechanical properties. [Solution] A thermosetting resin composition for an intermediate substrate, comprising a urethane (meth)acrylate (X) and a polymerizable monomer (Y), wherein the urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a bifunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group, and the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq.

Description

Technical Field

[0001] The present invention relates to a thermosetting resin composition for an intermediate substrate.

Background Art

[0002] Fiber Reinforced Plastics (FRP) are lightweight and high-strength, and are therefore used in various structural members. These fields cover a wide range, including housing equipment, automobiles, ships, civil engineering, sports equipment, etc. In recent years, the use of FRP has been increasing particularly in the fields of automobiles and transportation-related equipment that require weight reduction.

[0003] Resins and fibers are used in the production of FRP. There are methods of molding using a liquid resin and methods of molding using an intermediate substrate (for example, SMC (Sheet Molding Compound), prepreg, etc.) in which the resin is impregnated into the fibers in advance to a semi-cured state. As methods of molding using an intermediate substrate, there are autoclave molding, sheet winding molding, oven molding, press molding, etc. These molding methods are molding methods in which the intermediate substrate is cut, laminated to the target thickness, and heated to be cured.

[0004] The intermediate substrate is produced by a solvent method in which a resin composition and a solvent are mixed, this is impregnated into a fiber substrate, and then the solvent is dried and removed to obtain the intermediate substrate, or a hot melt method in which the viscosity of the resin composition is reduced by heating to produce a film of the resin composition, this is attached above and below a fiber substrate in which continuous fibers are aligned in one direction, and the resin composition is impregnated into the fiber substrate by heating and pressurizing to obtain the intermediate substrate.

[0005] As the matrix resin of the intermediate substrate, a resin composition containing a thermosetting resin excellent in impregnability to reinforcing fibers and heat resistance after curing is used. As the thermosetting resin, unsaturated polyester resin, vinyl ester resin, epoxy resin, phenol resin, melamine resin, bismaleimide resin, etc. are used.

[0006] For example, Patent Document 1 discloses a liquid composition for fiber-reinforced plastic intermediate materials, which is intended to suppress voids and improve mechanical properties and heat resistance. This composition is characterized by containing a composition comprising a compound having two or more isocyanate groups, and a composition comprising a vinyl ester resin and an ethylenically unsaturated group-containing monoalcohol compound.

[0007] Furthermore, Patent Document 2 describes that a prepreg sheet obtained by impregnating fibers with a radical polymerizable resin composition containing at least a specific urethane methacrylate compound provides excellent FRP mechanical properties and also exhibits excellent curing and storage properties. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2023-070793 [Patent Document 2] Japanese Patent Publication No. 2017-214463 [Overview of the project] [Problems that the invention aims to solve]

[0009] As mentioned above, FRP is used in applications such as automobiles and transportation-related equipment, requiring high heat resistance. However, modifying the resin structure to improve heat resistance resulted in a problem where the cured product became brittle, reducing its mechanical strength. Therefore, there was a need for a molding material for FRP that could achieve both strength and heat resistance. Therefore, the object of the present invention is to provide a thermosetting resin composition for intermediate materials that can produce fiber-reinforced plastics with excellent heat resistance and mechanical properties. [Means for solving the problem]

[0010] The present inventors have found that a thermosetting resin composition for intermediate materials containing a specific urethane (meth)acrylate and a polymerizable monomer can solve the above problems. In other words, the present invention relates to the following: [1] A thermosetting resin composition for intermediate substrates, comprising a urethane (meth)acrylate (X) and a polymerizable monomer (Y), wherein the urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a bifunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group, and the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq. [2] The thermosetting resin composition for intermediate substrates according to [1] above, wherein the polymerizable monomer (Y) comprises a polymerizable monomer with two or more functionalities. [3] The thermosetting resin composition for intermediate substrates according to [2] above, wherein the bifunctional or more polymerizable monomer is at least one selected from the group consisting of alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate. [4] A thermosetting resin composition for an intermediate substrate according to any one of [1] to [3] above, wherein the alcohol compound (B1) having two or more (meth)acrylic groups is pentaerythritol tri(meth)acrylate. [5] A thermosetting resin composition for an intermediate substrate according to any one of [1] to [4] above, wherein the alcohol compound (B2) having one (meth)acrylic group is a hydroxyalkyl (meth)acrylate. [6] A thermosetting resin composition for intermediate substrates according to any one of [1] to [5] above, wherein the mass ratio [(B1) / (B2)] of structural units derived from two or more alcohol compounds (B1) having one (meth)acrylic group to structural units derived from an alcohol compound (B2) having one (meth)acrylic group is 1 / 99 to 60 / 40. [7] A thermosetting resin composition for intermediate materials according to any one of [1] to [6] above, wherein the content of polymerizable monomer (Y) in the thermosetting resin composition for intermediate materials is 10 to 45% by mass. [8] A thermosetting resin composition for intermediate materials according to any one of [1] to [7] above, wherein the content of urethane (meth)acrylate (X) in the thermosetting resin composition for intermediate materials is 55 to 90% by mass. [9] A thermosetting resin composition for intermediate substrates according to any one of [1] to [8] above, wherein the viscosity at 85°C is 4 to 10 Pa·s.

[10] A fiber-reinforced plastic intermediate substrate obtained by impregnating a fiber material with a radical polymerizable composition containing a thermosetting resin composition for intermediate substrates and a curing agent as described in any one of [1] to [9] above.

[11] A method for producing a fiber-reinforced plastic intermediate substrate, comprising the step of impregnating a fiber material with a radical polymerizable composition containing a thermosetting resin composition for intermediate substrates and a curing agent as described in any one of [1] to [9] above.

[12] A fiber-reinforced composite material obtained by curing the fiber-reinforced plastic intermediate material described in

[10] above. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a thermosetting resin composition for intermediate materials that can produce fiber-reinforced plastics with excellent heat resistance and mechanical properties. [Modes for carrying out the invention]

[0012] [Thermosetting resin composition for intermediate base material] The thermosetting resin composition for intermediate substrates of the present invention contains a urethane (meth)acrylate (X) and a polymerizable monomer (Y), wherein the urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a bifunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group, and the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq. Because the thermosetting resin composition for intermediate substrates of the present invention has the above-described structure, it is possible to obtain a fiber-reinforced plastic with excellent heat resistance and mechanical properties.

[0013] The reason why the thermosetting resin composition for intermediate materials of the present invention, having the above-mentioned structure, can produce a fiber-reinforced plastic with excellent heat resistance and mechanical properties is not entirely clear, but it is thought to be as follows. The thermosetting resin composition for intermediate substrates of the present invention allows for a relatively small acrylic equivalent in the cured resin product by using an alcohol compound having one (meth)acrylic group, as well as an alcohol compound having two or more (meth)acrylic groups, as a raw material. Furthermore, by using a polyfunctional isocyanate having an isocyanurate ring as a raw material, the toughness of the cured resin product is increased. Therefore, it is believed that a fiber-reinforced plastic with excellent heat resistance and mechanical properties can be obtained.

[0014] <Urethane (meth)acrylate (X)> The thermosetting resin composition for an intermediate substrate of the present invention contains urethane (meth)acrylate (X), and the urethane (meth)acrylate (X) has a structural unit derived from a polyfunctional isocyanate (A) having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound, a structural unit derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and a structural unit derived from an alcohol compound (B2) having one (meth)acrylic group, and the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq. In the present invention, “(meth)acrylate” means at least one selected from the group consisting of “acrylate” and “methacrylate”, “(meth)acryloyl group” means at least one selected from the group consisting of “acryloyl group” and “methacryloyl group”, and “(meth)acrylic acid” means at least one selected from the group consisting of “acrylic acid” and “methacrylic acid”.

[0015] Incidentally, “polyfunctional isocyanate (A) having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound” is also simply referred to as “polyfunctional isocyanate (A)”. “Alcohol compound (B1) having two or more (meth)acrylic groups” and “alcohol compound (B2) having one (meth)acrylic group” are also simply referred to as “alcohol compound (B1) having a (meth)acrylic group”, “alcohol compound (B2) having a (meth)acrylic group” or “alcohol compound (B1)”, “alcohol compound (B2)”.

[0016] (Polyfunctional isocyanate (A)) The urethane (meth)acrylate (X) has a structural unit derived from a polyfunctional isocyanate (A) having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound. The bifunctional isocyanate compound constituting the polyfunctional isocyanate (A) having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound is at least one selected from the group consisting of an aromatic isocyanate compound, an alicyclic isocyanate compound, and an aliphatic isocyanate compound. At least one selected from the group consisting of an alicyclic isocyanate compound and an aliphatic isocyanate compound is preferred, and an alicyclic isocyanate compound is more preferred.

[0017] Examples of the aromatic isocyanate compound include 1,3-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, m-tetramethylxylylene diisocyanate, and the like. Examples of the alicyclic isocyanate compound include hydrogenated xylylene diisocyanate (1,3-bis(isocyanatomethyl)cyclohexane), isophorone diisocyanate, norbornene diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated methylene bisphenylene diisocyanate, 1,4-cyclohexane diisocyanate, and the like. Examples of the aliphatic isocyanate compound include 1,6-hexamethylene diisocyanate, trimethylene diisocyanate, and the like. These isocyanate compounds may constitute the polyfunctional isocyanate (A) alone or in combination of two or more, but it is preferred to constitute the polyfunctional isocyanate (A) alone.

[0018] The difunctional isocyanate compound is preferably at least one selected from the group consisting of 1,6-hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and isophorone diisocyanate, more preferably at least one selected from the group consisting of 1,6-hexamethylene diisocyanate and isophorone diisocyanate, and even more preferably isophorone diisocyanate. That is, the polyfunctional isocyanate (A) having a trimarinated isocyanurate ring of the difunctional isocyanate compound is preferably a polyfunctional isocyanate having a trimarinated isocyanurate ring of isophorone diisocyanate. By using isophorone diisocyanate, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0019] Polyfunctional isocyanates (A) have an isocyanurate ring. The isocyanurate ring is formed by the trimerization of a bifunctional isocyanate compound. The number of isocyanurate rings (integer) in polyfunctional isocyanate (A) is preferably 1 to 10, more preferably 1 to 5, even more preferably 1 to 3, even more preferably 1 or 2, and even more preferably 1. Polyfunctional isocyanate (A2) may be a mixture of molecules having 1 to 10 isocyanurate rings, and in the case of a mixture, it is preferable that there are many molecules with fewer isocyanurate rings.

[0020] Polyfunctional isocyanate (A) is a compound in which a difunctional isocyanate compound is increased, and three difunctional isocyanate compounds constitute an isocyanurate ring. The number of structural units (integers) derived from the difunctional isocyanate compound in polyfunctional isocyanate (A) is preferably 3 to 21, more preferably 3 to 11, even more preferably 3 to 7, even more preferably 3 to 5, and even more preferably 3. When the number of isocyanurate rings in the polyfunctional isocyanate (A) and the number of structural units derived from the bifunctional isocyanate compound are within the above range, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0021] (Alcohol compounds having a (meth)acrylic group (B1) and (B2)) The urethane (meth)acrylate (X) has structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups and structural units derived from an alcohol compound (B2) having one (meth)acrylic group. The resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties because the urethane (meth)acrylate (X) has structural units derived from alcohol compounds (B1) and (B2) having (meth)acrylic groups.

[0022] The alcohol compound (B1) having two or more (meth)acrylic groups is preferably at least one selected from the group consisting of trimethylolpropanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate, and more preferably pentaerythritol tri(meth)acrylate.

[0023] The alcohol compound (B2) having one (meth)acrylic group is preferably at least one selected from the group consisting of hydroxyalkyl (meth)acrylate, hydroxyphenoxypropyl (meth)acrylate, and polyalkylene glycol (meth)acrylate, and more preferably hydroxyalkyl (meth)acrylate. The hydroxyalkyl (meth)acrylate is preferably at least one selected from the group consisting of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, more preferably at least one selected from the group consisting of hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, even more preferably hydroxyethyl (meth)acrylate, and even more preferably hydroxyethyl methacrylate. The polyalkylene glycol (meth)acrylate is preferably at least one selected from the group consisting of polyethylene glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate.

[0024] (Composition and properties of urethane (meth)acrylate (X)) Urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a difunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group.

[0025] The ratio of structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring in the urethane (meth)acrylate (X) is preferably 40 to 85% by mass, more preferably 50 to 80% by mass, and even more preferably 60 to 75% by mass. When the ratio of structural units derived from polyfunctional isocyanate (A) is within the above range, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0026] The ratio of structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups and structural units derived from an alcohol compound (B2) having one (meth)acrylic group in the urethane (meth)acrylate (X) is preferably 15 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 25 to 40% by mass. When the ratio of structural units derived from alcohol compounds (B1) and (B2) is within the above range, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0027] In urethane (meth)acrylate (X), the mass ratio [(B1) / (B2)] of structural units derived from alcohol compounds (B1) having two or more (meth)acrylic groups to structural units derived from alcohol compounds (B2) having one (meth)acrylic group is preferably 1 / 99 to 60 / 40, more preferably 2 / 98 to 50 / 50, even more preferably 3 / 97 to 40 / 60, and even more preferably 3 / 97 to 35 / 65. Furthermore, from the viewpoint of mechanical properties, it is even more preferably 3 / 97 to 10 / 90, and even more preferably 4 / 96 to 8 / 92. On the other hand, from the viewpoint of heat resistance, it is even more preferably 5 / 95 to 35 / 65, and even more preferably 8 / 92 to 30 / 70. When the mass ratio of structural units derived from alcohol compounds (B1) and (B2) is within the above range, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0028] In urethane (meth)acrylate (X), the mass ratio [(A) / ((B1)+(B2))] of structural units derived from polyfunctional isocyanate (A) to the total of structural units derived from alcohol compound (B1) and structural units derived from alcohol compound (B2) is preferably 40 / 60 to 85 / 15, more preferably 50 / 50 to 80 / 20, and even more preferably 60 / 40 to 75 / 25. When the mass ratio of the structural units is within the above range, the resulting fiber-reinforced plastic exhibits excellent heat resistance and mechanical properties.

[0029] The acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq. By having the acrylic equivalent of the urethane (meth)acrylate (X) within this range, it is possible to obtain a resin composition that imparts toughness to the resulting fiber-reinforced plastic while also exhibiting excellent heat resistance. The acrylic equivalent of urethane (meth)acrylate (X) is preferably 370 to 460 g / eq, more preferably 400 to 450 g / eq, even more preferably 410 to 440 g / eq, even more preferably 420 to 440 g / eq, and even more preferably 425 to 435 g / eq. By having the acrylic equivalent of urethane (meth)acrylate (X) within the above range, a resin composition with particularly excellent mechanical properties of the cured product can be obtained.

[0030] (Method of manufacturing urethane (meth)acrylate (X)) There are no restrictions on the method for producing urethane (meth)acrylate (X), but it is preferably obtained by the following method. A difunctional isocyanate compound can be obtained by forming a urethane bond between the isocyanate group of a polyfunctional isocyanate (A) having a trimerized isocyanurate ring and the hydroxyl groups of an alcohol compound (B1) having two or more (meth)acrylic groups and an alcohol compound (B2) having one (meth)acrylic group. In addition to the polyfunctional isocyanate (A) and alcohol compounds (B1) and (B2), isocyanate compounds and alcohol compounds may also be used, but it is preferable to use substantially only the polyfunctional isocyanate (A) and alcohol compounds (B1) and (B2).

[0031] In the isocyanate compound used as a raw material for urethane (meth)acrylate (X), the proportion of polyfunctional isocyanate (A) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 99% by mass or more, and may even be 100% by mass. The isocyanate compound used as a raw material for urethane (meth)acrylate (X) may consist only of polyfunctional isocyanate (A), and it is even more preferable that it consists only of polyfunctional isocyanate (A).

[0032] In the alcohol compound used as a raw material for urethane (meth)acrylate (X), the total ratio of alcohol compounds (B1) and (B2) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 99% by mass or more, and may even be 100% by mass. The alcohol compound used as a raw material for urethane (meth)acrylate (X) may consist only of alcohol compounds (B1) and (B2), and it is even more preferable that it consists only of alcohol compounds (B1) and (B2).

[0033] A urethane catalyst may be used in the reaction that forms the urethane bond. The urethane catalyst is preferably an acidic catalyst or a basic catalyst, and more preferably a tin compound such as dibutyltin dilaurate or dibutyltin diacetate. The amount of urethane catalyst used is preferably 0.0002 to 0.01% by mass, more preferably 0.0005 to 0.005% by mass, and even more preferably 0.001 to 0.003% by mass, relative to the total amount of isocyanate compound and alcohol compound, which are raw materials for urethane (meth)acrylate (X). By having the urethane catalyst content within the above range, the rate of urethane (meth)acrylate formation and the storage stability of the intermediate material can be improved, thereby improving storage stability and workability, and the resulting fiber-reinforced plastic will also have excellent mechanical properties.

[0034] The production of urethane (meth)acrylate (X), that is, the reaction to form urethane bonds, can be carried out using an isocyanate compound, an alcohol compound, and a urethane formation catalyst. Other components are optional, but from the viewpoint of efficiently obtaining a homogeneous thermosetting resin composition for intermediate materials, it is preferable to carry out the reaction to form urethane bonds in the presence of the raw materials constituting the thermosetting resin composition for intermediate materials of the present invention. In other words, a preferred method for producing urethane (meth)acrylate (X) involves heating and reacting a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a difunctional isocyanate compound, an alcohol compound (B1) having two or more (meth)acrylic groups, an alcohol compound (B2) having one (meth)acrylic group, a polymerizable monomer (Y), and an optional urethane catalyst to obtain urethane (meth)acrylate (X). This reaction yields a thermosetting resin composition for intermediate substrates containing urethane (meth)acrylate (X) and a polymerizable monomer (Y).

[0035] Polymerization inhibitors include quinones such as hydroquinone, monomethyl ether hydroquinone, toluhydroquinone, di-t-4-methylphenol, monomethyl ether hydroquinone, phenothiazine, t-butylcatechol, parabenzoquinone, and pyrogallol; 2,6-di-t-butyl-p-cresol, 2,2-methylenebis(4-methyl-6-t-butylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenol). Examples include phenolic compounds such as nyl)butane; and piperidine-1-oxyl compounds such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 2,2,6,6-tetramethylpiperidine-1-oxyl. Storage stability and workability can be improved by using polymerization inhibitors. These may be used alone or in combination of two or more.

[0036] The content of the polymerization inhibitor in the liquid composition for the intermediate base material is preferably 0.0005 to 0.05% by mass, more preferably 0.001 to 0.04% by mass, and even more preferably 0.005 to 0.03% by mass. By keeping the polymerization inhibitor content within the above range, storage stability and workability can be improved, and the liquid composition for intermediate materials can be maintained at a low viscosity.

[0037] <Polymerizable monomer (Y)> The thermosetting resin composition for intermediate substrates of the present invention contains a polymerizable monomer (Y). The polymerizable monomer (Y) acts as a diluent before curing, giving fluidity to the resin composition and functioning as a solvent for the resin. After curing, it acts as a crosslinked portion, improving the strength and hardness of the resulting cured product. Therefore, in this invention, the inclusion of polymerizable monomer (Y) makes it easier to impregnate the fiber material when obtaining a fiber-reinforced plastic intermediate substrate, resulting in a fiber-reinforced plastic with excellent heat resistance and mechanical properties.

[0038] The polymerizable monomer (Y) may be a monofunctional polymerizable monomer or a polymerizable monomer with two or more functions. The polymerizable monomer with two or more functions is preferably a polymerizable monomer with 2 to 6 functions, more preferably a polymerizable monomer with 2 to 4 functions, and even more preferably at least one selected from the group consisting of a polymerizable monomer with two functions and a polymerizable monomer with four functions. The polymerizable monomer (Y) preferably comprises at least one selected from the group consisting of bifunctional or more polymerizable monomers and monofunctional polymerizable monomers, more preferably comprises bifunctional or more polymerizable monomers, even more preferably comprises bifunctional or more polymerizable monomers, and even more preferably comprises only bifunctional or more polymerizable monomers. The inclusion of a bifunctional or more polymerizable monomer (Y) further improves the heat resistance and mechanical properties of the resulting cured product.

[0039] Furthermore, it is preferable that the polymerizable monomer (Y) does not contain isocyanate-reactive groups. This is preferable because the absence of isocyanate-reactive groups prevents reaction with isocyanate during storage and during the production of urethane (meth)acrylate (X).

[0040] The polymerizable monomer (Y) is preferably at least one selected from the group consisting of styrene monomers, (meth)acrylic acid monomers, and vinyl acetate monomers, more preferably at least one selected from the group consisting of styrene monomers and (meth)acrylic acid monomers, and even more preferably a (meth)acrylic acid monomer.

[0041] As the styrene monomer, at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene is preferred, with styrene being more preferred.

[0042] The (meth)acrylic acid monomer preferably comprises a (meth)acrylic acid monomer with two or more functions, more preferably a (meth)acrylic acid monomer with two or more functions, and even more preferably consists only of a (meth)acrylic acid monomer with two or more functions. The (meth)acrylic acid monomer with two or more functions is preferably a (meth)acrylic acid monomer with two to six functions, more preferably a (meth)acrylic acid monomer with two to four functions, and even more preferably at least one selected from the group consisting of a bifunctional (meth)acrylic acid monomer and a tetrafunctional (meth)acrylic acid monomer.

[0043] The monofunctional (meth)acrylic acid monomer is preferably at least one selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid esters, and polyalkylene glycol mono(meth)acrylates, more preferably at least one selected from the group consisting of (meth)acrylic acid esters and polyalkylene glycol mono(meth)acrylates, and even more preferably (meth)acrylic acid esters. The bifunctional or more (meth)acrylic acid monomer is preferably at least one selected from the group consisting of alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate, and more preferably at least one selected from the group consisting of polyalkylene glycol mono(meth)acrylate and pentaerythritol tetra(meth)acrylate. Therefore, the bifunctional or more polymerizable monomer is preferably at least one selected from the group consisting of alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate, and more preferably at least one selected from the group consisting of polyalkylene glycol mono(meth)acrylate and pentaerythritol tetra(meth)acrylate.

[0044] Examples of alkylene glycol di(meth)acrylates include ethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, norbornene dimethanol di(meth)acrylate, and tricyclodecanedimethanol di(meth)acrylate, with ethylene glycol di(meth)acrylate being preferred among them.

[0045] Examples of polyalkylene glycol di(meth)acrylates include triethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate, with diethylene glycol di(meth)acrylate being the most preferred.

[0046] The (meth)acrylic acid ester is preferably at least one selected from the group consisting of phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and alkyl (meth)acrylate, more preferably at least one selected from the group consisting of phenoxyethyl (meth)acrylate and benzyl (meth)acrylate, and even more preferably phenoxyethyl (meth)acrylate.

[0047] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate.

[0048] As described above, the polymerizable monomer (Y) preferably comprises at least one selected from the group consisting of alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate, which is a polymerizable monomer with two or more functionalities; more preferably comprises at least one selected from the group consisting of polyalkylene glycol di(meth)acrylate and pentaerythritol tetra(meth)acrylate; and even more preferably is at least one selected from the group consisting of polyalkylene glycol di(meth)acrylate and pentaerythritol tetra(meth)acrylate.

[0049] <Composition, properties, and manufacturing method of thermosetting resin composition for intermediate substrates> The thermosetting resin composition for intermediate substrates of the present invention contains urethane (meth)acrylate (X) and polymerizable monomer (Y) as described above.

[0050] The content of urethane (meth)acrylate (X) in the thermosetting resin composition for intermediate materials is preferably 55 to 90% by mass, more preferably 60 to 90% by mass, even more preferably 65 to 90% by mass, even more preferably 70 to 90% by mass, and even more preferably 75 to 85% by mass. By having the urethane (meth)acrylate (X) content within the above range, the resulting fiber-reinforced plastic will have excellent heat resistance and mechanical properties.

[0051] The content of polymerizable monomer (Y) in the thermosetting resin composition for intermediate substrates is preferably 10 to 45% by mass, more preferably 10 to 40% by mass, even more preferably 10 to 35% by mass, even more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. By setting the content of polymerizable monomer (D) within the above range, it is possible to easily impregnate the fibers during the production of the intermediate substrate, achieve low viscosity, and obtain good mechanical properties for the resulting fiber-reinforced plastic.

[0052] The mass ratio of polymerizable monomer (Y) to urethane (meth)acrylate (X) [(Y) / (X)] is preferably 10 / 90 to 40 / 60, more preferably 10 / 90 to 35 / 65, more preferably 10 / 90 to 30 / 70, even more preferably 10 / 90 to 25 / 75, and even more preferably 15 / 85 to 25 / 75. When the mass ratio of polymerizable monomer (Y) to urethane (meth)acrylate (X) is within the above range, it is easy to impregnate the fibers during the intermediate material manufacturing process, resulting in a low viscosity and a fiber-reinforced plastic with excellent heat resistance and mechanical properties.

[0053] The thermosetting resin composition for intermediate substrates of the present invention may contain components other than urethane (meth)acrylate (X) and polymerizable monomer (Y), as long as the effects of the present invention are not impaired. Other components besides urethane (meth)acrylate (X) and polymerizable monomer (Y) include polymerization inhibitors, pigments, low-shrinkage agents, internal release agents, and dispersants. In particular, the thermosetting resin composition for intermediate substrates of the present invention preferably contains a polymerization inhibitor to improve storage stability and workability, and to prevent the reaction of (meth)acryloyl groups during urethane (meth)acrylate (X) synthesis.

[0054] Polymerization inhibitors include quinones such as hydroquinone, monomethyl ether hydroquinone, methyl hydroquinone (toluhydroquinone), di-t-4-methylphenol, monomethyl ether hydroquinone, phenothiazine, t-butylcatechol, parabenzoquinone, and pyrogallol; 2,6-di-t-butyl-p-cresol, 2,2-methylenebis(4-methyl-6-t-butylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t- Phenolic compounds such as butylphenyl)butane; piperidine-1-oxyl compounds such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 2,2,6,6-tetramethylpiperidine-1-oxyl. These may be used alone or in combination of two or more.

[0055] The content of polymerization inhibitor in the thermosetting resin composition for intermediate materials is preferably 0.001 to 0.05% by mass, more preferably 0.005 to 0.04% by mass, and even more preferably 0.01 to 0.03% by mass. Having the polymerization inhibitor content within the above range improves storage stability and workability, and prevents the reaction of (meth)acryloyl groups during urethane (meth)acrylate (X) synthesis.

[0056] There are no restrictions on the method for producing the thermosetting resin composition for intermediate materials, but it is preferable to produce it by the method described above for producing urethane (meth)acrylate (X). In other words, a preferred method for producing a thermosetting resin composition for intermediate substrates involves mixing a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a difunctional isocyanate compound, an alcohol compound (B1) having two or more (meth)acrylic groups, an alcohol compound (B2) having one (meth)acrylic group, a polymerizable monomer (Y), and an optional component such as a urethane catalyst or polymerization inhibitor to obtain a mixture, and then heating and reacting this mixture to obtain urethane (meth)acrylate (X). This reaction yields a thermosetting resin composition for intermediate substrates containing urethane (meth)acrylate (X) and polymerizable monomer (Y).

[0057] The viscosity of the thermosetting resin composition for intermediate substrates of the present invention at 85°C is preferably 4 to 10 Pa·s, and more preferably 5 to 9 Pa·s. Having the viscosity of the thermosetting resin composition for intermediate substrates within this range at 85°C ensures good impregnation into the substrate.

[0058] As described above, the thermosetting resin composition for intermediate substrates of the present invention is a raw material for fiber-reinforced plastics with excellent heat resistance and mechanical properties, and can therefore be suitably used as a raw material for fiber-reinforced plastics in various applications, including the automotive and transportation-related equipment fields.

[0059] <Fiber-reinforced plastic intermediate substrate, and method for manufacturing fiber-reinforced plastic intermediate substrate> The fiber-reinforced plastic intermediate substrate of the present invention is a fiber-reinforced plastic intermediate substrate obtained by impregnating a fiber material with a radical polymerizable composition containing the thermosetting resin composition for intermediate substrates and a curing agent. In other words, the fiber-reinforced plastic intermediate substrate of the present invention is a fiber-reinforced plastic intermediate substrate obtained by impregnating a fiber material with a thermosetting resin composition for intermediate substrates containing a curing agent, and a radical polymerizable composition containing a curing agent, wherein the urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a bifunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group, and the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq. Therefore, fiber-reinforced plastics manufactured using the fiber-reinforced plastic intermediate material of the present invention exhibit excellent heat resistance and mechanical properties.

[0060] The radical polymerizable composition impregnated into the fiber material contains the thermosetting resin composition for the intermediate substrate and a curing agent. The curing agent is preferably an organic peroxide that decomposes with heat. The 10-hour half-life temperature of the organic peroxide is preferably 80 to 150°C, more preferably 90 to 140°C, and even more preferably 110 to 130°C. Within this range, a sufficient pot life is obtained, and the curing speed is also excellent.

[0061] The organic peroxide is preferably at least one selected from the group consisting of ketone peroxide compounds, diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, dialkyl peroxide compounds, and peroxyketal compounds, and more preferably at least one selected from the group consisting of peroxyester compounds and dialkyl peroxide compounds.

[0062] Examples of ketone peroxide compounds include methyl ethyl ketone peroxide and acetylacetone peroxide. Examples of diacyl peroxide compounds include dibenzoyl peroxide. Examples of peroxyester compounds include t-butyl peroxybenzoate, t-butyl peroxyoctoate, and t-butyl peroxy-2-ethylhexyl monocarbonate. Examples of dialkyl peroxide compounds include dicumyl peroxide and t-butylcumyl peroxide. Examples of peroxyketal compounds include 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, and 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane. Organic peroxides may be used individually or in combination of two or more types. Among these, at least one selected from the group consisting of t-butylperoxy-2-ethylhexyl monocarbonate and t-butylcumyl peroxide is more preferred from the viewpoint of freedom in molding conditions and storage stability.

[0063] The curing agent can be appropriately selected based on the maturation temperature, molding temperature, and storage temperature of the intermediate substrate, and can be used alone or in a mixture of two or more types.

[0064] The content of the curing agent in the radical polymerizable composition is preferably 0.5 to 3.0% by mass, more preferably 0.8 to 2.5% by mass, and even more preferably 1.0 to 2.0% by mass. By keeping the curing agent content within the above range, it is possible to obtain a cured product with the desired mechanical properties, and to improve the degree of freedom in molding conditions and storage stability of the intermediate substrate.

[0065] The radical polymerizable composition may contain a urethane catalyst. Preferably, the urethane catalyst is a tin compound such as dibutyltin dilaurate or dibutyltin diacetate. The content of the urethane catalyst in the radical polymerizable composition is preferably 0.0002 to 0.01% by mass, more preferably 0.0005 to 0.005% by mass, and even more preferably 0.001 to 0.003% by mass. By having a urethane catalyst content within the above range, the reaction between the fiber and the resin is promoted, thereby improving the mechanical properties.

[0066] The fibers used in the fiber-reinforced plastic intermediate material of the present invention are not particularly limited, but are preferably at least one selected from the group consisting of carbon fibers, glass fibers, aramid fibers, Zylon fibers, boron fibers, basalt fibers, and cellulose, more preferably at least one selected from the group consisting of carbon fibers and glass fibers, and even more preferably carbon fibers.

[0067] The fiber content in the fiber-reinforced plastic intermediate material is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, even more preferably 40 to 70% by mass, and even more preferably 50 to 70% by mass. By keeping the fiber content within the above range, a good balance is achieved between mechanical properties and moldability. The fibers may be surface-treated fibers. Furthermore, there are no particular restrictions on the shape of the fibers, but examples include unidirectional, cross, NCF, and nonwoven fabrics. The fibers may have a layered structure including a core material. Specifically, they may be laminated fibers obtained by sandwiching a core material between two fiber substrates. Examples of core materials include foamed nonwoven fabrics and honeycomb core mats.

[0068] A preferred method for producing a fiber-reinforced plastic intermediate material comprises the step of impregnating a fiber material with a radical polymerizable composition containing the thermosetting resin composition for the intermediate material and a curing agent. In this manufacturing method, first, the thermosetting resin composition for the intermediate substrate and the curing agent are mixed to obtain a radical polymerizable composition. A urethane catalyst may also be mixed in at that time. In other words, it is preferable to mix the thermosetting resin composition for the intermediate substrate, the curing agent, and the urethane catalyst to obtain a radical polymerizable composition.

[0069] Next, the obtained radical polymerizable composition is impregnated into the fiber material. The temperature in the step of impregnating the fiber material with the radical polymerizable composition is preferably 10 to 100°C, more preferably 30 to 100°C, even more preferably 50 to 100°C, and even more preferably 60 to 90°C. Furthermore, if necessary, the radical polymerizable composition may be sandwiched between films and impregnated into the fibrous material using roller pressure to form a sheet, roll, or bound material. More specifically, one method involves coating a film or release paper with a radical polymerizable composition, placing fibers on the coated surface, then placing another film or similar on top, and applying pressure with a roller to impregnate the fibers with the radical polymerizable composition. Alternatively, fibers may be placed on a film or similar first, the radical polymerizable composition may be dropped onto it, then another film or similar on top, and pressure may be applied with a roller to impregnate the fibers with the radical polymerizable composition. In this way, a fiber-reinforced plastic intermediate material (prepreg) in which the resin before curing is formed on the fibers can be obtained.

[0070] <Fiber-reinforced composite materials> The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material obtained by curing the aforementioned fiber-reinforced plastic intermediate substrate. The fiber-reinforced composite material of the present invention can be obtained by placing the fiber-reinforced plastic intermediate substrate into a mold, applying heat and pressure to induce radical polymerization, curing, molding, and obtaining a cured product. Examples of molding methods that involve applying heat and pressure include the autoclave method, oven molding, sheet winding molding, and press molding.

[0071] The molding temperature can be appropriately adjusted depending on the type of curing agent contained in the radical polymerizable composition, but the molding temperature is preferably 70 to 180°C, more preferably 110 to 170°C, and even more preferably 140 to 170°C. The molding time is preferably 3 to 60 minutes, more preferably 5 to 30 minutes. The molding pressure is preferably 0.1 to 10 MPa, more preferably 0.2 to 5 MPa, and more preferably 0.3 to 2 MPa.

[0072] The fiber-reinforced composite material obtained as described above uses the aforementioned thermosetting resin composition for intermediate base materials as a raw material, and therefore exhibits excellent heat resistance and mechanical properties. The fiber-reinforced composite material of the present invention can achieve both heat resistance and mechanical properties, and can be suitably used in various applications, including in the fields of automobiles and transportation-related equipment. [Examples]

[0073] The following describes in more detail one embodiment of the present invention with reference to examples, but the present invention is not limited in any way to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0074] <Manufacturing of thermosetting resin compositions for intermediate substrates> Example 1 Isophorone diisocyanate trimer (VESTANAT T1890 / 100 (product name), including pentamers, heptamers, necapers and 11mers or more, manufactured by Evonik), pentaerythritol triacrylate and pentaerythritol tetraacrylate (Aronics M-305 (product name), 56% by mass of pentaerythritol triacrylate, 44% by mass of pentaerythritol tetraacrylate, manufactured by Toagosei Co., Ltd.), 2-hydroxyethyl methacrylate (manufactured by Nippon Shokubai Co., Ltd.), diethylene glycol dimethacrylate (NK Ester 2G (product name), manufactured by Shin Nakamura Chemical Industry Co., Ltd.), dibutylhydroxytoluene, methyl hydroquinone, and dibutyltin dilaurate were charged into a container in the mass ratios shown in Table 1, and the reaction was carried out under a flow of air at a temperature of 110°C. The reaction was monitored by IR, and the absorption of the isocyanate group (2270 cm) was observed.-1 The reaction was terminated when the (approximately) constant was reached, and a thermosetting resin composition for intermediate substrates was obtained. The reaction took 3 hours.

[0075] Example 2 A thermosetting resin composition for an intermediate substrate was obtained in the same manner as in Example 1, except that the mass ratio of each component was adjusted to the mass ratio shown in Table 1.

[0076] Example 3 In Example 1, diethylene glycol dimethacrylate (NK Ester 2G (product name), manufactured by Shin Nakamura Chemical Industry Co., Ltd.) was replaced with phenoxyethyl methacrylate (Light Ester PO (product name), manufactured by Kyoeisha Chemical Co., Ltd.), and the composition was prepared in the same manner as in Example 1, except that the mass ratio of each component was as shown in Table 1.

[0077] Comparative Example 1 In Example 1, pentaerythritol triacrylate and pentaerythritol tetraacrylate (Aronics M-305 (product name), 56% by mass of pentaerythritol triacrylate, 44% by mass of pentaerythritol tetraacrylate, manufactured by Toagosei Co., Ltd.) were not included, and the composition was prepared in the same manner as in Example 1, except that the mass ratios of each component were as shown in Table 1.

[0078] Comparative Examples 2 and 3 In Example 3, a thermosetting resin composition for an intermediate substrate was obtained in the same manner as in Example 3, except that the mass ratio of each component was adjusted to the mass ratio shown in Table 1.

[0079] <Manufacturing of fiber-reinforced plastic intermediate materials> (Radical polymerizable composition) Dibutyltin dilaurate and tert-butylcumyl peroxide (manufactured by NOF Corporation, product name: Perbutyl C) or tert-butylperoxy-2-ethylhexyl monocarbonate (manufactured by NOF Corporation, product name: Perbutyl E) were blended into each resin composition of Examples 1-3 and Comparative Examples 1-3 in the mass ratios shown in Table 1 to obtain radical polymerizable compositions.

[0080] (Fiber-reinforced plastic intermediate material) The radical polymerizable composition was applied to release paper using a roll coater heated to 80°C. Next, a carbon fiber fabric (manufactured by Mitsubishi Chemical Corporation, product name: TR3523M) was placed on the coating of the radical polymerizable composition, and release paper was laminated on top of it. Then, it was passed through a roller heated to 90°C and pressure was applied to impregnate the carbon fiber fabric with the radical polymerizable composition. One side of the release paper was peeled off, and a polyethylene film was laminated to obtain a prepreg sheet (fiber-reinforced plastic intermediate material) containing 40% by mass of the radical polymerizable composition and 60% by mass of carbon fiber.

[0081] <Manufacturing of fiber-reinforced composite materials> Using the aforementioned prepreg sheet, a molded plate made of fiber-reinforced composite material (fiber-reinforced plastic) was obtained by molding it with a 100-ton hydraulic press (manufactured by Toho Press Manufacturing Co., Ltd.). The molding temperature of the prepreg sheets using the thermosetting resin compositions for intermediate substrates in Examples 1 and 2 and Comparative Example 1 was 150°C, the molding pressure was 7 bar, and the molding time was 10 minutes. The molding temperature of the prepreg sheets using the thermosetting resin compositions for intermediate substrates in Example 3 and Comparative Examples 2 and 3 was 150°C, the molding pressure was 6 bar, and the molding time was 15 minutes.

[0082] <Acrylic equivalent of urethane (meth)acrylate> The acrylic equivalent of urethane (meth)acrylate was determined using the following formula.

number

[0083] <Evaluation of fiber-reinforced composite materials (fiber-reinforced plastics)> (1) Evaluation of heat resistance The heat resistance of the aforementioned molded plate was evaluated as follows. The heat resistance was evaluated by measuring the inflection point of the storage modulus (E'-Onset Tg: Tg at E'-Onset) using a dynamic viscoelasticity analyzer (product name: RSA-G2, manufactured by TA Instruments). A larger E'-Onset Tg value indicates a higher heat resistance temperature for the fiber-reinforced composite material, which is preferable. In particular, an E'-Onset Tg value exceeding 200°C is suitable for applications of fiber-reinforced plastics where heat resistance is required. The results are shown in Table 1.

[0084] (2) Evaluation of mechanical properties The mechanical properties of the molded plate were evaluated as follows. Interlaminar shear strength was measured according to the method specified in JIS K7078:1991. A higher interlaminar shear strength value indicates greater strength in the fiber-reinforced composite material, which is preferable. The results are shown in Table 1.

[0085] [Table 1]

[0086] Table 1 shows that the fiber-reinforced composite materials (molded boards, fiber-reinforced plastics) obtained using the thermosetting resin compositions for intermediate substrates in the examples exhibit excellent heat resistance due to their high E'-Onset Tg values, and also have excellent mechanical properties due to their high interlaminar shear strength values. From this, it can be seen that the thermosetting resin composition for intermediate materials of the present invention can produce fiber-reinforced plastics that are particularly excellent in heat resistance and mechanical properties. Thus, fiber-reinforced plastics obtained from the thermosetting resin composition for intermediate materials of the present invention can achieve both heat resistance and mechanical properties, and can be suitably used in various applications, including in the fields of automobiles and transportation-related equipment.

Claims

1. It contains urethane (meth)acrylate (X) and polymerizable monomer (Y), The urethane (meth)acrylate (X) has structural units derived from a polyfunctional isocyanate (A) having a trimerized isocyanurate ring of a difunctional isocyanate compound, structural units derived from an alcohol compound (B1) having two or more (meth)acrylic groups, and structural units derived from an alcohol compound (B2) having one (meth)acrylic group. A thermosetting resin composition for intermediate substrates, wherein the acrylic equivalent of the urethane (meth)acrylate (X) is 340 to 470 g / eq.

2. The thermosetting resin composition for intermediate substrates according to claim 1, wherein the polymerizable monomer (Y) comprises a polymerizable monomer with two or more functionalities.

3. The thermosetting resin composition for intermediate substrates according to claim 2, wherein the bifunctional or more polymerizable monomer is at least one selected from the group consisting of alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

4. The thermosetting resin composition for intermediate substrates according to claim 1 or 2, wherein the alcohol compound (B1) having two or more (meth)acrylic groups is pentaerythritol tri(meth)acrylate.

5. The thermosetting resin composition for intermediate substrates according to claim 1 or 2, wherein the alcohol compound (B2) having one (meth)acrylic group is a hydroxyalkyl (meth)acrylate.

6. A thermosetting resin composition for an intermediate substrate according to claim 1 or 2, wherein the mass ratio [(B1) / (B2)] of structural units derived from two or more alcohol compounds (B1) having (meth)acrylic groups to structural units derived from one alcohol compound (B2) having one (meth)acrylic group is 1 / 99 to 60 / 40.

7. The thermosetting resin composition for intermediate materials according to claim 1 or 2, wherein the content of polymerizable monomer (Y) in the thermosetting resin composition for intermediate materials is 10 to 45% by mass.

8. The thermosetting resin composition for intermediate substrates according to claim 1 or 2, wherein the content of urethane (meth)acrylate (X) in the thermosetting resin composition for intermediate substrates is 55 to 90% by mass.

9. A thermosetting resin composition for an intermediate substrate according to claim 1 or 2, wherein the viscosity at 85°C is 4 to 10 Pa·s.

10. A fiber-reinforced plastic intermediate substrate obtained by impregnating a fiber material with a radical polymerizable composition containing the thermosetting resin composition for intermediate substrates and a curing agent according to claim 1 or 2.

11. A method for producing a fiber-reinforced plastic intermediate substrate, comprising the step of impregnating a fiber material with a radical polymerizable composition containing the thermosetting resin composition for intermediate substrates and a curing agent described in claim 1 or 2.

12. A fiber-reinforced composite material obtained by curing the fiber-reinforced plastic intermediate material according to claim 10.

Images