Multilayer molding

Abstract

To provide a multilayer molding which is excellent in flame retardancy, and is excellent in shape retention and electric characteristics even after having been brought into contact with flame and become high temperature.SOLUTION: A multilayer molding contains a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order, wherein both of the two glass fiber sheet-containing layers are positioned on the surface, both of the two glass fiber sheet-containing layers contain a glass fiber sheet, the cured product layer is formed of a cured product obtained by curing a compound containing a thermosetting resin, a polymerizable monomer, a low constrictive agent, a curing agent, a polymerization initiator, a filler and a reinforcement fiber base material, and the filler contains aluminum hydroxide.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a multilayer molded article.

Background Art

[0002] As a material for electrical components, a compound containing a thermosetting resin such as an unsaturated polyester resin and a filler is used in terms of electrical insulation and strength. Among compounds, sheet molding compound is a sheet-shaped molding material in which a fibrous substrate such as glass fiber or organic fiber is impregnated in a paste-like composition containing a thermosetting resin and a vinyl monomer as a diluent. Because of its short molding cycle, it has the characteristic that a large amount of homogeneous products can be manufactured. Sheet molding compound is mainly used as a molding material for bathtubs, water storage tanks, septic tanks, etc., but is also used as a material for electrical components, such as plugs, lighting members, and breaker bases of household appliances. As a material for electrical components, high flame retardancy is required from the viewpoint of safety against fire. Therefore, attempts have been made to develop a resin material having flame retardancy by adding a flame retardant or the like. For example, Patent Document 1 discloses an unsaturated polyester resin composition containing a resin component containing an unsaturated polyester, a polymerizable monomer, and a low shrinkage agent which is polyvinyl acetate, aluminum hydroxide, and a flame retardant in specific amounts, respectively, for the purpose of improving flame retardancy in addition to low shrinkage and dimensional stability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a fire occurs and an electrical component comes into contact with a flame, there are problems such as the shape retention of the resin material used in the electrical component deteriorating, which may expose the energized part, and the risk of electric shock due to the deterioration of electrical insulation. Using a resin material containing a flame retardant in the electrical component was also insufficient as a countermeasure against these problems. This is presumably because even in a resin material containing a flame retardant, the combustible components become gas, the molded product becomes brittle, and the shape retention deteriorates. Also, when in contact with a flame, it is thought that the surface layer part carbonizes and becomes conductive, reducing the electrical insulation. Therefore, an object of the present invention is to provide a multilayer molded product that is excellent in flame retardancy and has excellent shape retention and electrical properties even after coming into contact with a flame and being heated to a high temperature.

Means for Solving the Problems

[0005] The present inventors have found that the above problems can be solved by a multilayer molded product containing a specific glass fiber sheet-containing layer and a specific cured product layer in a specific order. That is, the present invention relates to the following. [1] A multilayer molded product containing a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order, both of the two glass fiber sheet-containing layers are located on the surface, both of the two glass fiber sheet-containing layers contain a glass fiber sheet, and the cured product layer is composed of a cured product obtained by curing a compound containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, a filler, and a reinforcing fiber base material, and the filler contains aluminum hydroxide. [2] The multilayer molded product according to [1] above, wherein the basis weight of the glass fiber sheet is 100 to 600 g / m 2 . [3] The multilayer molded product according to [1] or [2] above, wherein the glass fiber sheet is at least one selected from the group consisting of a glass fiber woven fabric and a glass fiber non-woven fabric. [4] The multilayer molded product according to any one of [1] to [3] above, wherein the content of the aluminum hydroxide is 100 to 240 parts by mass when the total content of the thermosetting resin, the polymerizable monomer, and the low shrinkage agent is 100 parts by mass. [5] The multilayer molded article according to any one of [1] to [4] above, wherein the compound is a sheet molding compound. [6] The multilayer molded article according to any one of [1] to [5] above, wherein the reinforcing fiber base material is made of glass fiber. [7] The multilayer molded article according to any one of [1] to [6] above, wherein the polymerizable monomer contains a styrene-based monomer. [8] A multilayer molded article obtained by sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler with glass fiber sheets and press molding. [9] A method for producing a multilayer molded article, which comprises a step of sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler with glass fiber sheets and press molding. [Effect of the Invention]

[0006] According to the present invention, there is provided a multilayer molded article having excellent flame retardancy and excellent shape retention and electrical properties even after being brought into contact with a flame and heated to a high temperature. Therefore, the multilayer molded article is useful as a material for use in electric parts. [Embodiments for Carrying Out the Invention]

[0007] [Multilayer Molded Article] The multilayer molded article of the present invention contains a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order. Both of the two glass fiber sheet-containing layers are located on the surface, and both of the two glass fiber sheet-containing layers contain a glass fiber sheet. The cured product layer is composed of a cured product obtained by curing a compound containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, a filler, and a reinforcing fiber base material, and the filler contains aluminum hydroxide. The multilayer molded article of the present invention provides a multilayer molded article that is excellent in flame retardancy and maintains its shape and electrical properties even after coming into contact with a flame and reaching a high temperature. Therefore, the multilayer molded article is useful as a material for electrical components. The reason why the multilayer molded article of the present invention can exhibit the above excellent effects is not clear, but it is considered as follows. Since the glass fiber sheet-containing layer located on the surface is integrated with the cured product layer by press molding, even after the flame contacts, the glass fibers maintain their function as a reinforcing layer, and the effect of shape retention is exerted, and it is considered that the shape retention property becomes good. Furthermore, since an electric insulation layer is formed by the exposure of the glass fibers on the surface layer, it is considered that the electrical properties become good. As described above, the multilayer molded article of the present invention is considered to have good shape retention and electrical properties.

[0008] <Glass fiber sheet-containing layer> The multilayer molded article of the present invention contains a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order. Both of the two glass fiber sheet-containing layers are located on the surface, and both of the two glass fiber sheet-containing layers contain a glass fiber sheet.

[0009] The glass fiber sheet-containing layer contains a glass fiber sheet, but is not composed only of the glass fiber sheet, and contains a glass fiber sheet and a cured product contained in the cured product layer. That is, the cured product is filled in the gaps between the fibers of the glass fiber sheet and between the unevenness of the surface of the multilayer molded article and the fibers of the glass fiber sheet. In the present invention, the glass fiber sheet-containing layer contains a glass fiber sheet and a cured product. The cured product contained in the glass fiber sheet-containing layer is the same as the cured product contained in the cured product layer, and the preferred cured product is also the same.

[0010] The glass fiber sheet contained in the glass fiber sheet-containing layer is preferably at least one selected from the group consisting of a glass fiber woven fabric and a glass fiber non-woven fabric, and more preferably a glass fiber non-woven fabric. A glass fiber fabric is a cloth-like sheet made by weaving glassy threads. A non-woven fabric is a paper-like sheet made by accumulating fibers and bonding, pressing, or fusing them. The glass fiber fabric is preferably at least one selected from the group consisting of a glass cloth and a glass roving cloth, more preferably a glass roving cloth. The glass fiber non-woven fabric is preferably at least one selected from the group consisting of a glass chopped strand mat, a glass continuous strand mat, a glass non-woven fabric, and a glass paper, more preferably at least one selected from the group consisting of a glass chopped strand mat, a glass continuous strand mat, and a glass non-woven fabric, still more preferably at least one selected from the group consisting of a glass chopped strand mat and a glass continuous strand mat, and even more preferably a glass chopped strand mat. By using the above glass fiber sheet, the multi-layer molded product becomes excellent in shape retention and electrical properties.

[0011] The glass fiber sheet is a sheet made of glassy fibers. As the material, at least one selected from the group consisting of E-glass and silica is preferable, and E-glass is more preferable. The basis weight of the glass fiber sheet is preferably 100 to 600 g / m 2 and more preferably 200 to 600 g / m 2 and still more preferably 200 to 500 g / m 2 and even more preferably 250 to 500 g / m 2 and even more preferably 300 to 500 g / m 2 Here, the basis weight refers to the mass per unit area.

[0012] <Cured product layer> The multilayer molded article of the present invention contains a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order, and the cured product layer is composed of a cured product obtained by curing a compound containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, a filler, and a reinforcing fiber base material, and the filler contains aluminum hydroxide. The cured product layer is a layer composed of a cured product obtained by curing a compound. The compound will be described below.

[0013] (Compound) The compound contains a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, a filler, and a reinforcing fiber base material, and the filler contains aluminum hydroxide. The compound is preferably a sheet molding compound. By the compound being a sheet molding compound, a multilayer molded article having flame retardancy, shape retention, and excellent electrical properties, which are the effects of the present invention, can be manufactured accurately and in large quantities.

[0014] 〔Thermosetting resin〕 The compound contains a thermosetting resin. The thermosetting resin contained in the compound is preferably at least one selected from the group consisting of an unsaturated polyester resin, a vinyl ester resin, and a urethane acrylate resin. Among these, an unsaturated polyester resin is more preferable. The thermosetting resin contained in the compound is more preferably a thermosetting resin having a halogen atom in order to further enhance flame retardancy, shape retention, and electrical properties, and still more preferably at least one selected from the group consisting of an unsaturated polyester resin having a halogen atom, a vinyl ester resin having a halogen atom, and a urethane acrylate resin having a halogen atom. Among these, an unsaturated polyester resin having a halogen atom is still more preferable.

[0015] The content of the thermosetting resin is preferably 5 to 20% by mass, more preferably 6 to 15% by mass, still more preferably 7 to 12% by mass, and even more preferably 8 to 11% by mass in the compound.

[0016] Unsaturated polyester resin The unsaturated polyester resin preferably contains structural units derived from saturated dicarboxylic acids, structural units derived from unsaturated dicarboxylic acids, and structural units derived from diols, and more preferably consists essentially of structural units derived from saturated dicarboxylic acids, structural units derived from unsaturated dicarboxylic acids, and structural units derived from diols.

[0017] The saturated dicarboxylic acid that provides the structural unit derived from a saturated dicarboxylic acid is preferably at least one selected from the group consisting of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids, and more preferably an aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, bromophthalic acid, etc. From the viewpoint of the balance between the availability of raw materials and the performance of the resulting unsaturated polyester, it is preferably at least one selected from the group consisting of terephthalic acid, isophthalic acid, and phthalic acid. The aromatic dicarboxylic acid may be used in the form of an anhydride. By using the aromatic dicarboxylic acid, an unsaturated polyester resin excellent in mechanical properties, water resistance, and chemical resistance can be obtained. Examples of the alicyclic dicarboxylic acid include 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, etc. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, azelaic acid, succinic acid substituted with an alkyl group having 16 to 18 carbon atoms, dimer acid, etc. The saturated dicarboxylic acid may be used alone or in combination of two or more.

[0018] Examples of the unsaturated dicarboxylic acid that provides a structural unit derived from an unsaturated dicarboxylic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, bromomaleic acid, chloromaleic acid, het acid, het acid anhydride, etc., preferably at least one selected from the group consisting of maleic acid, maleic anhydride, and fumaric acid, more preferably at least one selected from the group consisting of maleic acid and maleic anhydride, and still more preferably maleic anhydride. The unsaturated dicarboxylic acid may be used alone or in combination of two or more.

[0019] Examples of the diol that provides a structural unit derived from a diol include aliphatic diol, alicyclic diol, etherified diphenol, polyalkylene glycol, diphenol, etc., preferably aliphatic diol. Examples of the aliphatic diol include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methylpropane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl 3-hydroxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, dipropylene glycol, 2,2-bis(bromomethyl)-1,3-propanediol, etc. Preferably, it is at least one selected from the group consisting of ethylene glycol, 1,2-propanediol (propylene glycol), dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol and 1,8-octanediol. More preferably, it is at least one selected from the group consisting of neopentyl glycol, propylene glycol and dipropylene glycol. Even more preferably, it is at least two selected from the group consisting of neopentyl glycol, propylene glycol and dipropylene glycol. Even more preferably, it is neopentyl glycol, propylene glycol and dipropylene glycol. The aliphatic diol may be used alone or in combination of two or more, and it is preferable to use in combination of two or more.

[0020] Examples of the alicyclic diol include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, etc. Examples of etherified diphenols include bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, brominated bisphenol A alkylene oxide adduct, brominated bisphenol F alkylene oxide adduct, brominated bisphenol S alkylene oxide adduct, and the like. Examples of polyalkylene glycols include polyethylene glycol, polyalkylene glycol, polytetramethylene glycol, and the like. Examples of diphenols include bisphenol A, bisphenol F, bisphenol S, brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, and the like. The diol may be used alone or in combination of two or more.

[0021] The unsaturated polyester resin may contain other structural units in addition to the structural units described above. Examples of components that provide other structural units include monocarboxylic acids, polycarboxylic acids having a valence of 3 or more, monoalcohols, polyhydric alcohols having a valence of 3 or more, and hydroxycarboxylic acids. Note that as the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid having a valence of 3 or more, hydroxycarboxylic acid), its lower alkyl ester and anhydride may be used.

[0022] As the unsaturated polyester resin, an unsaturated polyester resin having a halogen atom is preferable from the viewpoint of further enhancing flame retardancy, shape retention, and electrical properties. The unsaturated polyester resin having a halogen atom contains a halogen atom, and preferably contains at least one selected from the group consisting of a component composed of a diol having a halogen atom and a component composed of a dicarboxylic acid having a halogen atom, and more preferably contains a component composed of a diol having a halogen atom. As the diol having a halogen atom, a diol containing bromine is preferable, and at least one selected from the group consisting of brominated bisphenol A and its alkylene oxide adduct, brominated bisphenol F and its alkylene oxide adduct, brominated bisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is more preferable, at least one selected from the group consisting of tetrabromobisphenol A and its alkylene oxide adduct, tetrabromobisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is still more preferable, and at least one selected from the group consisting of 2,2-bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane and 2,2-bis(bromomethyl)-1,3-propanediol is even more preferable. As the dicarboxylic acid having a halogen atom, at least one selected from the group consisting of a dicarboxylic acid containing bromine and a dicarboxylic acid containing chlorine is preferable, and a dicarboxylic acid containing bromine is more preferable. As the dicarboxylic acid containing bromine, at least one selected from the group consisting of bromomaleic acid and bromophthalic acid is preferable. As the dicarboxylic acid containing chlorine, at least one selected from the group consisting of chloromaleic acid, het acid and het acid anhydride is preferable.

[0023] The molar ratio [carboxyl group / hydroxyl group] of the total of the carboxyl groups of the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid having a valence of 3 or more, hydroxycarboxylic acid) to the total of the hydroxyl groups of the alcohol component (diol, monoalcohol, polyalcohol having a valence of 3 or more, hydroxycarboxylic acid) is preferably 0.9 / 1.1 to 1.1 / 0.9, and more preferably 0.95 / 1.05 to 1.05 / 0.95. The ratio (mol) of the structural unit derived from the unsaturated dicarboxylic acid in the structural unit derived from the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid with a valence of 3 or more, hydroxycarboxylic acid) is preferably 70 to 99 mol%, more preferably 80 to 99 mol%, still more preferably 90 to 99 mol%, and even more preferably 90 to 98 mol% in terms of the number of carboxyl groups converted. The ratio (mol) of the structural unit derived from the diol in the structural unit derived from the alcohol component (diol, monoalcohol, polyalcohol with a valence of 3 or more, hydroxycarboxylic acid) is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, still more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol% in terms of the number of hydroxyl groups converted. The structural unit derived from the alcohol component may consist only of the structural unit derived from the diol.

[0024] The method for producing the unsaturated polyester resin is not particularly limited, but it can be obtained by reacting the carboxylic acid component and the alcohol component described above. In that case, an esterification catalyst may be used. Examples of the esterification catalyst include at least one metal compound selected from antimony, germanium, titanium, tin, zinc, aluminum, and manganese. The addition amount of the esterification catalyst is preferably 0.01 to 1.5 mol% based on the saturated carboxylic acid component. In addition, in order to suppress the reaction of the unsaturated bond, a polymerization inhibitor may be added as necessary. Examples of the polymerization inhibitor include polyhydric phenol-based polymerization inhibitors such as hydroquinone, toluohydroquinone, trimethylhydroquinone, and tertiary butyl catechol, and quinone-based polymerization inhibitors such as para-benzoquinone and tolquinone. The addition amount of the polymerization inhibitor is preferably 0.002 to 1.0 part by mass, more preferably 0.005 to 0.3 part by mass, based on 100 parts by mass of the total amount of the carboxylic acid component and the alcohol component. The reaction temperature is preferably 150 to 280°C, more preferably 160 to 250°C. The end point of the reaction can be determined by the acid value of the reaction mixture, the amount of condensed water (alcohol in the case of using a lower alkyl ester as a raw material), the viscosity of the resulting polyester, etc.

[0025] [[Vinyl ester resin]] The vinyl ester resin is not particularly limited, but can be a polymer obtained by an addition reaction of an epoxy resin and an unsaturated carboxylic acid, and is also called epoxy acrylate. The epoxy resin is not particularly limited, and epi-bis type glycidyl ether, novolac type glycidyl ether, brominated glycidyl ether, other glycidyl ethers, nitrogen-containing type, glycidyl ester, peracetic acid oxidation type, glycol type glycidyl ether, etc. can be used, and they may be used alone or in combination of two or more. The epoxy resin is not particularly limited, and a bisphenol type epoxy compound is preferable, and it is more preferable to be at least one selected from the group consisting of bisphenol A type epoxy compound, bisphenol F type epoxy compound, and bisphenol S type epoxy compound, and bisphenol A type epoxy compound is still more preferable. As the vinyl ester resin, a vinyl ester resin having a halogen atom is preferable from the viewpoint of further enhancing flame retardancy, shape retention, and electrical properties. The vinyl ester resin having a halogen atom contains a halogen atom, and preferably contains a component composed of an epoxy resin having a halogen atom. As the epoxy resin having a halogen atom, a brominated bisphenol type epoxy compound is preferable, and it is more preferable to be at least one selected from the group consisting of brominated bisphenol A type epoxy compound, brominated bisphenol F type epoxy compound, and brominated bisphenol S type epoxy compound, and brominated bisphenol A type epoxy compound is still more preferable. The unsaturated carboxylic acid is not particularly limited, and it is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, sorbic acid, hydroxymethyl methacrylate / maleate, hydroxyethyl acrylate / maleate, hydroxypropyl methacrylate / maleate, hydroxypropyl acrylate / maleate, and dicyclopentadiene acrylate / maleate. These may be used alone or in combination of two or more.

[0026] The method for producing the vinyl ester resin is not particularly limited, and it may be according to a conventionally known method. Specifically, the vinyl ester resin can be produced by the method described in "Vinyl Ester Resin" (edited by the Vinyl Ester Resin Research Group, Chemical Industry Daily, 1993).

[0027] 〔Urethane acrylate resin〕 The urethane acrylate resin is not particularly limited, but is a radically polymerizable compound having a urethane bond and a (meth)acrylate group in the molecule, and constitutes a molded product by molding and curing. In the present invention, "(meth)acrylate" means at least one selected from the group consisting of "acrylate" and "methacrylate".

[0028] The urethane acrylate resin used in the present invention is not particularly limited, and may be an adduct of a (meth)acrylate having a hydroxy group of a polyisocyanate. The "adduct of a (meth)acrylate having a hydroxy group of a polyisocyanate" is an adduct obtained by forming a urethane bond from the isocyanate group of the polyisocyanate and the hydroxy group (hydroxyl group) of the (meth)acrylate having a hydroxy group. In addition, the urethane acrylate resin used in the present invention may further contain a component composed of a polyol or a polyester polyol, preferably contains a component composed of a polyol or a polyester polyol, more preferably contains a component composed of a polyol, and still more preferably contains a component composed of a polyol having a halogen atom.

[0029] Examples of the polyisocyanate include aromatic isocyanate compounds, alicyclic isocyanate compounds, aliphatic isocyanate compounds, etc. At least one selected from the group consisting of alicyclic isocyanate compounds and aliphatic isocyanate compounds is preferable, and both an alicyclic isocyanate compound and an aliphatic isocyanate compound are more preferable. Further, a trifunctional isocyanate having an isocyanurate ring formed by trimerization of a bifunctional isocyanate compound (nurate type polyisocyanate), an isocyanate prepolymer modified with a polyol, etc. are also preferably used.

[0030] 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, etc. 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, etc. Examples of the aliphatic isocyanate compound include 1,6-hexamethylene diisocyanate, trimethylene diisocyanate, etc. These isocyanate compounds can be used alone or in combination of two or more.

[0031] Among the polyisocyanates, at least one selected from the group consisting of 1,6 - hexamethylene diisocyanate, 1,3 - bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, and their nurate - type polyisocyanates is preferred. At least one selected from the group consisting of 1,6 - hexamethylene diisocyanate, isophorone diisocyanate, and their nurate - type polyisocyanates is more preferred. Isophorone diisocyanate and their nurate - type polyisocyanates are even more preferred.

[0032] As the (meth)acrylate having a hydroxy group, hydroxyalkyl (meth)acrylate is preferred. Examples of the hydroxyalkyl (meth)acrylate include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyphenoxypropyl (meth)acrylate, etc. Hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate are preferred, and hydroxyethyl (meth)acrylate is more preferred.

[0033] When a component comprising a polyol or a polyester polyol is included, examples of the polyol that can be used include aliphatic diols, etherified diphenols, etc. Examples of the polyester polyol include those obtained by polycondensing at least one selected from the group consisting of unsaturated acids and saturated acids and at least one selected from the group consisting of aliphatic diols and etherified diphenols. As the urethane acrylate resin, from the viewpoint of further enhancing flame retardancy, shape retention, and electrical properties, a urethane acrylate resin having a halogen atom is preferred. The urethane acrylate resin having a halogen atom contains a halogen atom, and preferably contains a component comprising a polyol having a halogen atom. As the polyol having a halogen atom, a glycol containing bromine is preferable, and at least one selected from the group consisting of brominated bisphenol A and its alkylene oxide adduct, brominated bisphenol F and its alkylene oxide adduct, brominated bisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is more preferable, at least one selected from the group consisting of tetrabromobisphenol A and its alkylene oxide adduct, tetrabromobisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is still more preferable, and at least one selected from the group consisting of 2,2-bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane and 2,2-bis(bromomethyl)-1,3-propanediol is even more preferable.

[0034] [Polymerizable monomer] The compound contains a polymerizable monomer. Before curing, the polymerizable monomer imparts fluidity to the resin composition as a diluent and also functions as a solvent for the resin. After curing, as a crosslinked portion, it can improve the strength and hardness of the obtained molded article. As the polymerizable monomer, at least one selected from the group consisting of styrene-based monomers, (meth)acrylic acid-based monomers, and vinyl acetate-based monomers is preferable, at least one selected from the group consisting of styrene-based monomers and (meth)acrylic acid-based monomers is more preferable, and a styrene-based monomer is still more preferable. As the styrene-based monomer, at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene is preferable, and styrene is more preferable. Examples of the (meth)acrylic acid-based monomer include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, acrylic (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like. The content of the polymerizable monomer is preferably 3 to 20% by mass, more preferably 5 to 15% by mass, still more preferably 5 to 10% by mass, and even more preferably 6 to 9% by mass, based on the total amount of the compound.

[0035] 〔Low shrinkage agent〕 The compound contains a low shrinkage agent. As the low shrinkage agent, at least one selected from polystyrene, polyvinyl acetate, a block copolymer of polystyrene / polyvinyl acetate, polyethylene, polypropylene, polymethyl methacrylate, a styrene-butadiene block copolymer, and a saturated polyester is preferable.

[0036] The content of the low shrinkage agent is preferably 2 to 10% by mass, more preferably 3 to 9% by mass, still more preferably 4 to 8% by mass, and even more preferably 5 to 7% by mass based on the total amount of the compound. By the content of the low shrinkage agent being within the above range, the shrinkage during the curing of the compound can be effectively suppressed, and the shape retention of the molded product can also be improved. In addition, the mass ratio of the total of the thermosetting resin and the polymerizable monomer to the low shrinkage agent [thermosetting resin and polymerizable monomer / low shrinkage agent] is preferably 60 / 40 to 90 / 10, and more preferably 65 / 35 to 80 / 20 from the viewpoints of suppressing shrinkage and the shape retention of the molded product.

[0037] 〔Curing agent〕 The compound contains a curing agent. The curing agent is used to quickly obtain a homogeneous cured product during molding. These types and amounts may be properly selected according to the application. The curing agent is preferably a peroxide. The peroxides are preferably at least one selected from the group consisting of ketone peroxide-based, diacyl peroxide-based, peroxyester-based, hydroperoxide-based, and dialkyl peroxide-based, and more preferably peroxyester-based. The content of the curing agent is preferably 0.05 to 3% by mass, more preferably 0.1 to 1% by mass, still more preferably 0.1 to 0.5% by mass, and even more preferably 0.2 to 0.3% by mass based on the total amount of the compound.

[0038] 〔Polymerization inhibitor〕 The compound contains a polymerization inhibitor. The polymerization inhibitor is compounded to prevent gelation during production, ensure the pot life during molding, and improve storage stability. Preferred polymerization inhibitors that can be used include polyhydric phenol-based polymerization inhibitors such as hydroquinone, toluhydroquinone, trimethylhydroquinone, and tertiary butyl catechol, and quinone-based polymerization inhibitors such as parabenzoquinone and tolquinone, and polyhydric phenol-based polymerization inhibitors are preferred. The content of the polymerization inhibitor is preferably 0.001 to 0.05% by mass, more preferably 0.002 to 0.02% by mass, based on the total amount of the compound.

[0039] 〔Filler〕 The compound includes a filler. The filler contains aluminum hydroxide. By using aluminum hydroxide as the filler, a sheet molding compound capable of obtaining a molded product with high shape retention even when in contact with a flame can be obtained.

[0040] The filler contained in the compound may contain a filler other than aluminum hydroxide as long as the effects of the present invention are not impaired. As the filler other than aluminum hydroxide, at least one selected from the group consisting of calcium carbonate and a silicon-based filler is preferable, and calcium carbonate is more preferable.

[0041] Examples of the silicon-based filler preferably include glass micro hollow sphere filler, silica micro hollow sphere filler, silica sand, diatomaceous earth, crystalline silica, amorphous silica, mica, and glass short fibers, etc., and at least one selected from the group consisting of glass micro hollow sphere filler and silica micro hollow sphere filler is preferable.

[0042] The content of the filler is preferably 30 to 70% by mass, more preferably 35 to 60% by mass, still more preferably 41 to 55% by mass, and even more preferably 43 to 50% by mass, based on the total amount of the compound. When the total content of the thermosetting resin, the polymerizable monomer, and the low shrinkage agent is 100 parts by mass, the content of the filler is preferably 100 to 240 parts by mass, more preferably 150 to 240 parts by mass, still more preferably 180 to 240 parts by mass, and even more preferably 200 to 240 parts by mass.

[0043] From the viewpoint of enhancing flame retardancy and shape retention, the content of aluminum hydroxide is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 65% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more, based on the total amount of the filler. There is no upper limit, and it is 100% by mass or less. It is even more preferable that the filler consists of aluminum hydroxide, and it is even more preferable that the filler consists only of aluminum hydroxide. From the viewpoint of enhancing flame retardancy and shape retention, the content of aluminum hydroxide is preferably 30 to 70% by mass, more preferably 35 to 60% by mass, still more preferably 41 to 55% by mass, and even more preferably 43 to 50% by mass, based on the total amount of the compound. From the viewpoint of enhancing flame retardancy and shape retention, when the total content of the thermosetting resin, the polymerizable monomer, and the low shrinkage agent is 100 parts by mass, the content of the filler is preferably 100 to 240 parts by mass, more preferably 150 to 240 parts by mass, still more preferably 180 to 240 parts by mass, and even more preferably 200 to 240 parts by mass.

[0044] 〔Other Components〕 The compound may contain, as other components, a thickener, a release agent, a wetting and dispersing agent, etc. These may be added during the synthesis of the thermosetting resin, mixed when blending the components of the resin composition, or mixed immediately before use, depending on the application.

[0045] The thickener is used to make the compound highly viscous. These types and amounts may be properly selected according to the application. The thickener is preferably at least one selected from the group consisting of oxides of alkaline earth metals and hydroxides of alkaline earth metals, and more preferably oxides of alkaline earth metals. As the oxide of the alkaline earth metal, magnesium oxide is preferable. As the hydroxide of alkaline earth metal, magnesium hydroxide and calcium hydroxide are preferable. The content of the thickener is preferably 0.1 to 3% by mass, more preferably 0.2 to 2% by mass, still more preferably 0.3 to 1% by mass, and even more preferably 0.4 to 0.5% by mass with respect to the total amount of the compound.

[0046] The release agent is blended to improve the releasability of the molded product and enhance the moldability. As the release agent, at least one selected from the group consisting of fatty acids, fatty acid metal salts, polyolefin waxes, petroleum waxes, and animal and plant waxes is preferable, and fatty acid metal salts are more preferable. Examples of the fatty acid include stearic acid and palmitic acid, and examples of the fatty acid metal salt include metal salts of stearic acid and metal salts of palmitic acid. Examples of the polyolefin wax include polyethylene wax and oxidized polyethylene wax. Examples of the petroleum wax include paraffin wax. Examples of the animal and plant wax include carnauba wax and montan wax. The release agent may be used alone or in combination of two or more. The content of the release agent is preferably 0.3 to 3% by mass, more preferably 0.5 to 2% by mass with respect to the total amount of the compound.

[0047] The wetting dispersant is blended to adjust the viscosity of the compound. Examples of the wetting dispersant include modified polyurethane, phosphate ester, and phosphate polyester. The wetting dispersant may be used alone or in combination of two or more. The content of the wetting dispersant is preferably 0.1 to 2.0% by mass, more preferably 0.3 to 1.0% by mass with respect to the total amount of the compound.

[0048] 〔Reinforced fiber base material〕 The compound includes a reinforced fiber base material. The reinforced fiber base material is preferably a base material made of glass fiber. The forms of the reinforcing fiber base material include roving, cloth, mat, fabric, chopped roving, chopped strand, etc., and at least one selected from the group consisting of chopped roving and chopped strand is preferred. The fiber base material may be used alone or two or more kinds may be appropriately mixed and used. The content of the reinforcing fiber base material is preferably 20 to 50% by mass, more preferably 20 to 45% by mass, still more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass based on the total amount of the compound.

[0049] [Manufacturing method of multilayer molded article] The multilayer molded article may be obtained by any manufacturing method, but it is preferably obtained by the manufacturing method shown below. This manufacturing method is also included in the present invention. The manufacturing method of the multilayer molded article of the present invention has a step of sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler with a glass fiber sheet and press molding. Therefore, the multilayer molded article of the present invention is preferably a multilayer molded article obtained by sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler with a glass fiber sheet and press molding. The multilayer molded article obtained by the above manufacturing method provides a multilayer molded article having excellent flame retardancy and excellent shape retention and electrical properties even after coming into contact with a flame and reaching a high temperature. Therefore, the multilayer molded article obtained by the above manufacturing method is useful as a material used for electrical parts.

[0050] [Sheet molding compound] The sheet molding compound is a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler.

[0051] (Resin composition) The resin composition constituting the sheet molding compound contains a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler.

[0052] 〔Thermosetting resin〕 The thermosetting resin contained in the resin composition is preferably at least one selected from the group consisting of an unsaturated polyester resin, a vinyl ester resin, and a urethane acrylate resin. Among these, the unsaturated polyester resin is more preferable. The thermosetting resin contained in the compound is more preferably a thermosetting resin having a halogen atom in order to further enhance flame retardancy, shape retention, and electrical properties. More preferably, it is at least one selected from the group consisting of an unsaturated polyester resin having a halogen atom, a vinyl ester resin having a halogen atom, and a urethane acrylate resin having a halogen atom. Among these, the unsaturated polyester resin having a halogen atom is even more preferable.

[0053] The content of the thermosetting resin is preferably 6 to 25% by mass, more preferably 8 to 15% by mass, still more preferably 9 to 15% by mass, and even more preferably 10 to 14% by mass in the resin composition.

[0054] The unsaturated polyester resin contained in the resin composition is the same as the unsaturated polyester resin described in the section of 〔Unsaturated polyester resin〕 contained in the compound, and the preferable unsaturated polyester resins are also the same. Specific unsaturated polyester resins are shown below.

[0055] The unsaturated polyester resin preferably contains a structural unit derived from a saturated dicarboxylic acid, a structural unit derived from an unsaturated dicarboxylic acid, and a structural unit derived from a diol, and more preferably consists essentially of a structural unit derived from a saturated dicarboxylic acid, a structural unit derived from an unsaturated dicarboxylic acid, and a structural unit derived from a diol.

[0056] The saturated dicarboxylic acid that provides the structural unit derived from a saturated dicarboxylic acid is preferably at least one selected from the group consisting of an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and an aliphatic dicarboxylic acid, and more preferably an aromatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, bromophthalic acid, etc. From the viewpoint of the balance between the availability of raw materials and the performance of the resulting unsaturated polyester, it is preferably at least one selected from the group consisting of terephthalic acid, isophthalic acid, and phthalic acid. The aromatic dicarboxylic acid may be used in the form of an anhydride. By using the aromatic dicarboxylic acid, an unsaturated polyester resin excellent in mechanical properties, water resistance, and chemical resistance can be obtained. Examples of the alicyclic dicarboxylic acid include 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, etc. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, azelaic acid, succinic acid substituted with an alkyl group having 16 to 18 carbon atoms, dimer acid, etc. The saturated dicarboxylic acid may be used alone or in combination of two or more.

[0057] Examples of the unsaturated dicarboxylic acid that provides a structural unit derived from an unsaturated dicarboxylic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, bromomaleic acid, chloromaleic acid, het acid, het acid anhydride, etc. Preferably, it is at least one selected from the group consisting of maleic acid, maleic anhydride, and fumaric acid, more preferably at least one selected from the group consisting of maleic acid and maleic anhydride, and still more preferably maleic anhydride. The unsaturated dicarboxylic acid may be used alone or in combination of two or more.

[0058] Examples of the diol that provides a structural unit derived from a diol include aliphatic diol, alicyclic diol, etherified diphenol, polyalkylene glycol, diphenol, etc. Preferably, it is an aliphatic diol. Examples of the aliphatic diol include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-methylpropane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,4-dimethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 3-hydroxy-2,2-dimethylpropyl 3-hydroxy-2,2-dimethylpropanoate, diethylene glycol, triethylene glycol, dipropylene glycol, 2,2-bis(bromomethyl)-1,3-propanediol, etc. Preferably, it is at least one selected from the group consisting of ethylene glycol, 1,2-propanediol (propylene glycol), dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, and 1,8-octanediol. More preferably, it is at least one selected from the group consisting of neopentyl glycol, propylene glycol, and dipropylene glycol. Even more preferably, it is at least two selected from the group consisting of neopentyl glycol, propylene glycol, and dipropylene glycol. Even more preferably, it is neopentyl glycol, propylene glycol, and dipropylene glycol. The aliphatic diol may be used alone or in combination of two or more, and it is preferable to use in combination of two or more.

[0059] Examples of the alicyclic diol include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, etc. Examples of the etherified diphenol include bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, brominated bisphenol A alkylene oxide adduct, brominated bisphenol F alkylene oxide adduct, brominated bisphenol S alkylene oxide adduct, and the like. Examples of the polyalkylene glycol include polyethylene glycol, polyalkylene glycol, polytetramethylene glycol, and the like. Examples of the diphenol include bisphenol A, bisphenol F, bisphenol S, brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, and the like. The diols may be used alone or in combination of two or more.

[0060] The unsaturated polyester resin may contain other structural units in addition to the structural units described above. Examples of the component that provides other structural units include monocarboxylic acid, polycarboxylic acid having a valence of 3 or more, monoalcohol, polyhydric alcohol having a valence of 3 or more, and hydroxycarboxylic acid. Note that as the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid having a valence of 3 or more, hydroxycarboxylic acid), its lower alkyl ester and anhydride may be used.

[0061] As the unsaturated polyester resin, an unsaturated polyester resin having a halogen atom is preferable from the viewpoint of further enhancing flame retardancy, shape retention, and electrical properties. The unsaturated polyester resin having a halogen atom contains a halogen atom, and preferably contains at least one selected from the group consisting of a component composed of a diol having a halogen atom and a component composed of a dicarboxylic acid having a halogen atom, and more preferably contains a component composed of a diol having a halogen atom. As the diol having a halogen atom, a diol containing bromine is preferable, and at least one selected from the group consisting of brominated bisphenol A and its alkylene oxide adduct, brominated bisphenol F and its alkylene oxide adduct, brominated bisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is more preferable, and at least one selected from the group consisting of tetrabromobisphenol A and its alkylene oxide adduct, tetrabromobisphenol S and its alkylene oxide adduct, and 2,2-bis(bromomethyl)-1,3-propanediol is still more preferable, and at least one selected from the group consisting of 2,2-bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane and 2,2-bis(bromomethyl)-1,3-propanediol is even more preferable. As the dicarboxylic acid having a halogen atom, at least one selected from the group consisting of a dicarboxylic acid containing bromine and a dicarboxylic acid containing chlorine is preferable, and a dicarboxylic acid containing bromine is more preferable. As the dicarboxylic acid containing bromine, at least one selected from the group consisting of bromomaleic acid and bromophthalic acid is preferable. As the dicarboxylic acid containing chlorine, at least one selected from the group consisting of chloromaleic acid, het acid, and het acid anhydride is preferable.

[0062] The molar ratio [carboxy group / hydroxy group] of the total of the carboxy groups of the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid having a valence of 3 or more, hydroxycarboxylic acid) to the total of the hydroxy groups of the alcohol component (diol, monoalcohol, polyalcohol having a valence of 3 or more, hydroxycarboxylic acid) is preferably 0.9 / 1.1 to 1.1 / 0.9, and more preferably 0.95 / 1.05 to 1.05 / 0.95. The ratio (mol) of the structural unit derived from unsaturated dicarboxylic acid in the structural unit derived from the carboxylic acid component (saturated dicarboxylic acid, unsaturated dicarboxylic acid, monocarboxylic acid, polycarboxylic acid with a valence of 3 or more, hydroxycarboxylic acid) is preferably 70 to 99 mol%, more preferably 80 to 99 mol%, still more preferably 90 to 99 mol%, and even more preferably 90 to 98 mol% in terms of the number of carboxyl groups converted. The ratio (mol) of the structural unit derived from diol in the structural unit derived from the alcohol component (diol, monoalcohol, polyalcohol with a valence of 3 or more, hydroxycarboxylic acid) is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, still more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol% in terms of the number of hydroxyl groups converted. The structural unit derived from the alcohol component may consist only of the structural unit derived from diol.

[0063] The vinyl ester resin contained in the resin composition is the same as the vinyl ester resin described in the section of [vinyl ester resin] contained in the compound, and the preferred vinyl ester resins are also the same.

[0064] The urethane acrylate resin contained in the resin composition is the same as the urethane acrylate resin described in the section of [urethane acrylate resin] contained in the compound, and the preferred urethane acrylate resins are also the same.

[0065] [Polymerizable monomer] The polymerizable monomer contained in the resin composition imparts fluidity to the resin composition as a diluent and also functions as a solvent for the resin before curing. After curing, it can improve the strength and hardness of the resulting molded product as a crosslinked part. The polymerizable monomer is preferably at least one selected from the group consisting of styrene-based monomers, (meth)acrylic acid-based monomers, and vinyl acetate-based monomers, more preferably at least one selected from the group consisting of styrene-based monomers and (meth)acrylic acid-based monomers, and still more preferably a styrene-based monomer. As the styrene monomer, at least one selected from the group consisting of styrene, vinyltoluene, and α-methylstyrene is preferable, and styrene is more preferable. Examples of the (meth)acrylic acid monomer include methyl methacrylate, methacrylic acid, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, acrylic (meth)acrylate, succinic acid 2-(meth)acryloyloxyethyl, maleic acid 2-(meth)acryloyloxyethyl, phthalic acid 2-(meth)acryloyloxyethyl, hexahydrophthalic acid 2-(meth)acryloyloxyethyl, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like. The content of the polymerizable monomer is preferably 4 to 30% by mass, more preferably 6 to 20% by mass, still more preferably 7 to 15% by mass, and even more preferably 8 to 13% by mass based on the total amount of the resin composition.

[0066] 〔Low shrinkage agent〕 As the low shrinkage agent contained in the resin composition, at least one selected from polystyrene, polyvinyl acetate, a block copolymer of polystyrene / polyvinyl acetate, polyethylene, polypropylene, polymethyl methacrylate, a styrene-butadiene block copolymer, and a saturated polyester is preferable.

[0067] The content of the low shrinkage agent is preferably 2 to 14% by mass, more preferably 4 to 10% by mass, still more preferably 5 to 9% by mass, and even more preferably 6 to 8% by mass, based on the total amount of the resin composition. When the content of the low shrinkage agent is within the above range, the shrinkage during the curing of the sheet molding compound can be effectively suppressed, and the shape retention of the molded product can also be improved. In addition, the mass ratio of the total of the thermosetting resin and the polymerizable monomer to the low shrinkage agent [thermosetting resin and polymerizable monomer / low shrinkage agent] is preferably 60 / 40 to 90 / 10, more preferably 65 / 35 to 80 / 20, from the viewpoints of suppressing shrinkage and the shape retention of the molded product.

[0068] 〔Curing agent〕 The curing agent contained in the resin composition is used to quickly obtain a homogeneous cured product during molding. These types and amounts may be properly selected according to the application. The curing agent is preferably a peroxide. The peroxides are preferably at least one selected from the group consisting of ketone peroxide-based, diacyl peroxide-based, peroxyester-based, hydroperoxide-based and dialkyl peroxide-based, and more preferably peroxyester-based. The content of the curing agent is preferably 0.05 to 3% by mass, more preferably 0.1 to 1% by mass, still more preferably 0.2 to 0.5% by mass, and even more preferably 0.3 to 0.4% by mass, based on the total amount of the resin composition.

[0069] 〔Polymerization inhibitor〕 The polymerization inhibitor contained in the resin composition is compounded for preventing gelation during production, ensuring the pot life during molding, and improving storage stability. Suitable polymerization inhibitors include polyhydric phenol-based polymerization inhibitors such as hydroquinone, toluohydroquinone, trimethylhydroquinone, and tertiary butyl catechol, and quinone-based polymerization inhibitors such as para-benzoquinone and tolquinone. Polyhydric phenol-based polymerization inhibitors are preferred. The content of the coincidence inhibitor is preferably 0.001 to 0.05% by mass, more preferably 0.002 to 0.02% by mass, based on the total amount of the resin composition.

[0070] 〔Filler〕 The filler contained in the resin composition contains aluminum hydroxide. By using aluminum hydroxide as the filler, a sheet molding compound capable of obtaining a molded product with high shape retention even when contacted with a flame can be obtained.

[0071] The filler contained in the resin composition may contain a filler other than aluminum hydroxide as long as the effects of the present invention are not impaired. As the filler other than aluminum hydroxide, at least one selected from the group consisting of calcium carbonate and a silicon-based filler is preferable, and calcium carbonate is more preferable.

[0072] As the silicon-based filler, preferably, glass micro hollow sphere filler, silica micro hollow sphere filler, silica sand, diatomaceous earth, crystalline silica, amorphous silica, mica, glass short fiber, etc. are mentioned, and at least one selected from the group consisting of glass micro hollow sphere filler and silica micro hollow sphere filler is preferable.

[0073] The content of the filler is preferably 40 to 80% by mass, more preferably 50 to 75% by mass, still more preferably 59 to 72% by mass, and even more preferably 62 to 70% by mass, based on the total amount of the resin composition. When the total content of the thermosetting resin, the polymerizable monomer and the low shrinkage agent is 100 parts by mass, the content of the filler is preferably 100 to 240 parts by mass, more preferably 150 to 240 parts by mass, still more preferably 180 to 240 parts by mass, and even more preferably 200 to 240 parts by mass.

[0074] From the perspective of enhancing flame retardancy and shape retention, the content of aluminum hydroxide is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 65% by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 99% by mass or more, based on the total amount of the filler. There is no upper limit, and it is 100% by mass or less. It is even more preferable that the filler consists of aluminum hydroxide, and it is even more preferable that the filler consists only of aluminum hydroxide. From the perspective of enhancing flame retardancy and shape retention, the content of aluminum hydroxide is preferably 40 to 80% by mass, more preferably 50 to 75% by mass, still more preferably 59 to 72% by mass, and even more preferably 62 to 70% by mass, based on the total amount of the resin composition. From the perspective of enhancing flame retardancy and shape retention, when the total content of the thermosetting resin, the polymerizable monomer, and the low shrinkage agent is 100 parts by mass, the content of the filler is preferably 100 to 240 parts by mass, more preferably 150 to 240 parts by mass, still more preferably 180 to 240 parts by mass, and even more preferably 200 to 240 parts by mass.

[0075] 〔Other Components〕 The resin composition may contain, as other components, a thickening agent, a release agent, a wetting and dispersing agent, etc. These may be added during the synthesis of the thermosetting resin, mixed when blending the components of the resin composition, or mixed immediately before use, depending on the application.

[0076] The thickening agent is used to make the compound highly viscous. These types and amounts may be properly selected according to the application. The thickening agent is preferably at least one selected from the group consisting of oxides of alkaline earth metals and hydroxides of alkaline earth metals, and more preferably oxides of alkaline earth metals. As the oxide of the alkaline earth metal, magnesium oxide is preferable. As the hydroxide of alkaline earth metal, magnesium hydroxide and calcium hydroxide are preferable. The content of the thickener is preferably 0.2 to 3% by mass, more preferably 0.3 to 2% by mass, still more preferably 0.4 to 1% by mass, and even more preferably 0.5 to 0.7% by mass based on the total amount of the resin composition.

[0077] The release agent is blended to improve the releasability of the molded product and enhance the moldability. As the release agent, at least one selected from the group consisting of fatty acids, fatty acid metal salts, polyolefin waxes, petroleum waxes, and animal / plant waxes is preferable, and fatty acid metal salts are more preferable. Examples of the fatty acid include stearic acid and palmitic acid, and examples of the fatty acid metal salt include metal salts of stearic acid and metal salts of palmitic acid. Examples of the polyolefin wax include polyethylene wax and oxidized polyethylene wax. Examples of the petroleum wax include paraffin wax. Examples of the animal / plant wax include carnauba wax and montan wax. The release agent may be used alone or in combination of two or more. The content of the release agent is preferably 0.4 to 3% by mass, more preferably 0.6 to 2% by mass based on the total amount of the resin composition.

[0078] The wetting dispersant is blended to adjust the viscosity of the compound. Examples of the wetting dispersant include modified polyurethane, phosphate ester, and phosphate polyester. The wetting dispersant may be used alone or in combination of two or more. The content of the wetting dispersant is preferably 0.2 to 2.5% by mass, more preferably 0.5 to 1.4% by mass based on the total amount of the resin composition.

[0079] (Reinforced fiber base material) The sheet molding compound is obtained by impregnating the resin composition into a reinforced fiber base material. The reinforcing fiber base material is preferably a base material made of glass fiber. Examples of the form of the reinforcing fiber base material include roving, cloth, mat, fabric, chopped roving, chopped strand, etc., and at least one selected from the group consisting of chopped roving and chopped strand is preferable. The fiber base material may be used alone or two or more kinds may be appropriately mixed and used. The content of the reinforcing fiber base material is preferably 20 to 50% by mass, more preferably 20 to 45% by mass, still more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass based on the total amount of the sheet molding compound.

[0080] (Manufacturing method of sheet molding compound) The manufacturing method of the sheet molding compound is not particularly limited, but it is preferably manufactured by the method shown below. The resin composition is impregnated into the reinforcing fiber base material to obtain a sheet-like compound, and both sides are covered with a film. By doing so, the handleability is improved. Specifically, the resin composition is applied to two films, the reinforcing fiber base material is scattered on the resin composition, the resin composition sides of the two films are bonded together, and the laminated film is pressurized from both sides to impregnate the resin composition into the reinforcing fiber base material. Then, it is aged to obtain a laminated sheet-like material using the semi-solid compound as an intermediate base material.

[0081] <Press molding process> The manufacturing method of the multilayer molded product of the present invention has a step of sandwiching both sides of the sheet molding compound with a glass fiber sheet and performing press molding. Specifically, a glass fiber sheet cut into a mold shape is inserted between the sheet molding compound, which is a sheet-like material, and the mold, and it is pressurized and heated and cured to obtain a multilayer molded product.

[0082] The glass fiber sheet is the same as the glass fiber sheet described in the glass fiber sheet-containing layer of the multilayer molded article, and the preferred glass fiber sheets are the same as well. Specifically, the glass fiber sheet used in this step is preferably at least one selected from the group consisting of a glass fiber fabric and a glass fiber nonwoven fabric, and more preferably a glass fiber nonwoven fabric. A glass fiber fabric is a cloth-like sheet made by weaving glassy yarns. A nonwoven fabric is a paper-like sheet made by accumulating fibers and bonding, pressing, or fusing them. As the glass fiber fabric, preferably, it is at least one selected from the group consisting of a glass cloth and a glass roving cloth, and more preferably a glass roving cloth. As the glass fiber nonwoven fabric, preferably, it is at least one selected from the group consisting of a glass chopped strand mat, a glass continuous strand mat, a glass nonwoven fabric, and a glass paper, more preferably at least one selected from the group consisting of a glass chopped strand mat, a glass continuous strand mat, and a glass nonwoven fabric, still more preferably at least one selected from the group consisting of a glass chopped strand mat and a glass continuous strand mat, and even more preferably a glass chopped strand mat. By using the above glass fiber sheet, the obtained multilayer molded article will be excellent in shape retention and electrical properties.

[0083] The glass fiber sheet is a sheet made of glassy fibers. As the material, at least one selected from the group consisting of E-glass and silica is preferable, and E-glass is more preferable. The basis weight of the glass fiber sheet is preferably 100 - 600 g / m 2 and more preferably 200 - 600 g / m 2 and still more preferably 200 - 500 g / m 2 and even more preferably 250 - 500 g / m 2 and even more preferably 300 - 500 g / m 2That is, the basis weight refers to the mass per unit area.

[0084] By the method as described above, a multilayer molded product containing a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order, and both of the two glass fiber sheet-containing layers are located on the surface and both contain a glass fiber sheet can be obtained. The multilayer molded product obtained by the above method provides a multilayer molded product that is excellent in flame retardancy and has excellent shape retention and electrical properties even after being in contact with a flame and reaching a high temperature. Therefore, the multilayer molded product is useful as a material used for electrical components.

Examples

[0085] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The measurements and evaluations in the present Examples were carried out by the following methods. The types of raw materials, the amounts of raw materials, the measurement results, and the evaluation results are shown in Table 1. The numbers of the amounts of raw materials are in "parts by mass".

[0086] <Flame Retardancy Evaluation (UL94 Vertical Burning Test)> According to the UL94 vertical burning test method, a flame retardancy test was carried out to evaluate the flame retardancy of the (multilayer) molded products obtained in the Examples and Comparative Examples. The thickness of the test piece was 2 mm. The results were evaluated according to the following criteria. Among those conforming to the UL94 standard, V-0 is the most excellent, followed by V-1 and V-2 in this order. (Evaluation Criteria) ◎: V-0 ○: V-1 △: V-2 ×: Does not conform to the UL94 standard

[0087] <Evaluation of Electrical Properties (Tracking Resistance Test)> The (multi-layer) molded articles obtained in the examples and comparative examples were cut into squares with sides of 10 cm to obtain flat plates for the tracking resistance test. The flat plates were gripped and fixed with two clamps. Next, a 500 W gas burner was applied from below the flat plates and heated for 10 minutes. At this time, the distance from the gas burner port to the flat plates was set to 90 mm. After 10 minutes, the gas burner was extinguished and the flat plates were cooled. The flat plates heat-treated as described above were evaluated for tracking resistance according to JIS-C-2134. The larger the tracking index (TI), the better the electrical insulation and the better the electrical properties. In this example, those with a tracking index (TI) exceeding 400 V have excellent electrical insulation and good electrical properties.

[0088] <Evaluation of shape retention (hardness test)> The (multi-layer) molded articles obtained in the examples and comparative examples were cut into squares with sides of 10 cm to obtain flat plates for the hardness test. The flat plates were gripped and fixed with two clamps. Next, a 500 W gas burner was applied from below the flat plates and heated for 10 minutes. At this time, the distance from the gas burner port to the flat plates was set to 80 mm. After 10 minutes, the gas burner was extinguished and the flat plates were cooled. A Shore A hardness tester was pressed against the center of the flat plates heat-treated as described above to measure the hardness of the molded articles after heat treatment. The larger the hardness value, the better the shape retention.

[0089] Production Example 1 (Production of unsaturated polyester resin) 713 parts by mass of dipropylene glycol, 1383 parts by mass of neopentyl glycol, and 441 parts by mass of isophthalic acid were charged into a glass reaction vessel equipped with a stirrer, a heating device, a thermometer, a fractionation device, and a nitrogen gas introduction tube, and polycondensation reaction was carried out at 210 °C with stirring under a nitrogen atmosphere. When the solid content acid value reached 10 mgKOH / g or less, it was cooled to 150 °C or less. Next, 647 parts by mass of 1,2-propanediol and 2343 parts by mass of maleic anhydride were further added, and polycondensation reaction was carried out at 210 °C with stirring under a nitrogen atmosphere. When the solid content acid value reached 27 mgKOH / g or less, it was cooled to terminate the reaction, and an unsaturated polyester resin (UP-1) was obtained.

[0090] Production Example 2 (Production of Unsaturated Polyester Resin) 3145 parts by mass of 2,2-bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane, 703 parts by mass of 1,2-propanediol, 42 parts by mass of phthalic anhydride, and 1366 parts by mass of maleic anhydride were charged into a glass reaction vessel equipped with a stirrer, a heating device, a thermometer, a fractionation device, and a nitrogen gas inlet tube. Under a nitrogen atmosphere, a polycondensation reaction was carried out at 190 °C for 8 hours with stirring. When the solid content acid value reached 35 mgKOH / g (the measurement method is JIS K 6901:2021. The same applies to the following production examples.), it was cooled to terminate the reaction, and an unsaturated polyester resin (UP-2) was obtained.

[0091] Production Example 3 (Production of Sheet Molding Compound) A resin composition was produced as follows. 43 parts by mass of unsaturated polyester resin UP-1, 32 parts by mass of styrene, 25 parts by mass of a 30% styrene solution of a polystyrene / polyvinyl acetate block copolymer (product name: Modiper SV30B30, manufactured by NOF Corporation), 0.01 parts by mass of hydroquinone (manufactured by Seiko Chemical Co., Ltd.), 1.0 part by mass of hexyl peracetate (product name: Perhexyl A, manufactured by NOF Corporation), 5 parts by mass of zinc stearate (product name: ZNS-P, manufactured by ADEKA Corporation), 210 parts by mass of aluminum hydroxide (product name: B-333L, manufactured by Almorix Co., Ltd.), and 3 parts by mass of a wetting dispersant (product name: BYK-W9010, manufactured by BYK-Chemie) were mixed and stirred to form a resin paste. Then, 2.0 parts by mass of magnesium oxide paste (product name: Magmicron MD-4AM-2, manufactured by Mikuni Shikiso Co., Ltd.) and 10 parts by mass of a gray pigment paste (manufactured by Tokyo Ink Co., Ltd.) were added and mixed to obtain a resin composition.

[0092] Next, a sheet molding compound was produced. The resin composition obtained as described above was applied to stretched carrier films made of polypropylene arranged vertically using a doctor blade so as to have a thickness of about 1 mm. Glass fiber chops (obtained by cutting glass rovings equivalent to TEX4800 into lengths of about 2.5 cm) were uniformly scattered over the resin composition applied to the film arranged below. The amount of the glass fiber chops was 30% by mass based on the total amount of the sheet molding compound (excluding the carrier film). The upper and lower resin compositions were bonded together so as to sandwich the glass fiber chops, and then pressure was applied to the whole to impregnate the glass fiber chops with the resin composition. Thereafter, it was stored at 35°C to 45°C for 24 hours to obtain a sheet molding compound.

[0093] Production Examples 4 to 6 (Production of Sheet Molding Compound) In Production Example 3, a sheet molding compound was obtained in the same manner as in Production Example 3, except that the raw materials of the resin composition were changed to the types and amounts shown in Table 1.

[0094]

Table 1

[0095] Example 1 (Production of Multilayer Molded Article) The sheet molding compound obtained in Production Example 3 was cut into a square (size: 250 mm × 250 mm). Two pieces of the cut sheet molding compound were stacked, and the two pieces of the sheet molding compound were sandwiched from both sides with a glass chopped strand mat (basis weight: 450 g / m 2 ) cut into a square (size: 300 mm × 300 mm) to obtain a laminated molding material of glass chopped strand mat / sheet molding compound / glass chopped strand mat. The laminated molding material was compression-molded by heating using a 300 mm × 300 mm flat metal plate. The molding conditions were a mold temperature of 140°C for both the front and back surfaces of the flat plate, a molding pressure of 8 MPa, and a holding time in the mold of 300 seconds. Thereafter, the molded product was demolded from the mold and immediately sandwiched between iron plates for cooling to obtain a flat multi-layer molded product with a thickness of 2 mm.

[0096] Examples 2 to 6 and Comparative Example 2 (Manufacture of multi-layer molded product) In Example 1, instead of the sheet molding compound obtained in Production Example 3, the sheet molding compounds shown in Table 2 were used, and instead of the glass chopped strand mat (basis weight: 450 g / m 2 ), a flat multi-layer molded product with a thickness of 2 mm was obtained in the same manner as in Example 1, except that the glass fiber sheets shown in Table 2 were used.

[0097] Comparative Example 1 (Manufacture of molded product) In Example 1, a molded product composed only of a cured product with a flat plate shape having a thickness of 2 mm was obtained in the same manner as in Example 1, except that a glass chopped strand mat (basis weight: 450 g / m 2 ) was not used.

[0098]

Table 2

[0099] From Table 2, it can be seen that the multi-layer molded products of the examples do not burn even in the combustion test and have high flammability. Furthermore, it can be seen that no tracking occurs in the tracking resistance test after heat treatment, and the electrical insulation is excellent. Also, it can be seen that the hardness after heat treatment is high and the shape is retained. From these facts, it can be understood that the multi-layer molded product of the present invention is excellent in flame retardancy and also excellent in shape retention and electrical properties even after being in contact with a flame and reaching a high temperature. Since the multi-layer molded product of the present invention has the above excellent properties, it is useful as a material for use in electrical components.

Claims

1. A multilayer molded article comprising a glass fiber sheet-containing layer, a cured product layer, and a glass fiber sheet-containing layer in this order, both of the two glass fiber sheet-containing layers are located on the surface, both of the two glass fiber sheet-containing layers contain a glass fiber sheet, the cured product layer is made of a cured product obtained by curing a compound containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, a filler, and a reinforcing fiber base material, the multilayer molded article, wherein the filler contains aluminum hydroxide.

2. The basis weight of the glass fiber sheet is 100 to 600 g / m 2 The multilayer molded product according to claim 1, which is such that.

3. The multilayer molded article according to claim 1 or 2, wherein the glass fiber sheet is at least one selected from the group consisting of a glass fiber woven fabric and a glass fiber nonwoven fabric.

4. The multilayer molded article according to claim 1 or 2, wherein the content of the aluminum hydroxide is 100 to 240 parts by mass when the total content of the thermosetting resin, the polymerizable monomer, and the low shrinkage agent is 100 parts by mass.

5. The multilayer molded article according to claim 1 or 2, wherein the compound is a sheet molding compound.

6. The multilayer molded article according to claim 1 or 2, wherein the reinforcing fiber base material is made of glass fiber.

7. The multilayer molded article according to claim 1 or 2, wherein the polymerizable monomer contains a styrene-based monomer.

8. A multilayer molded article obtained by sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler between glass fiber sheets and press molding.

9. A method for manufacturing a multilayer molded article, comprising the step of sandwiching both sides of a sheet molding compound obtained by impregnating a reinforcing fiber base material with a resin composition containing a thermosetting resin, a polymerizable monomer, a low shrinkage agent, a curing agent, a polymerization inhibitor, and aluminum hydroxide as a filler between glass fiber sheets and press molding.

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