JPH09176331A - High-strength sheet molding compound of unsaturated polyester resin and its molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-strength sheet molding compound of an unsaturated polyester resin capable of being molded at a low temperature under low pressure while having high strength without inducing air bubble in a molded material and capable of obtaining a beautiful molded material by mixing high-density glass fiber woven fabric as a reinforcing agent and thermoplastic resin powder as a thickener. SOLUTION: This high-strength sheet molding compound is composed of (A) 100 pts.wt. of an unsaturated polyester resin, (B) 30-120 pts.wt. of a liquid polymerizable monomer, (C) 40-180 pts.wt. of glass fiber woven fabric, (D) 20-120 pts.wt. of a thickener composed of thermoplastic resin powder and (E) 0.5-7 pts.wt. of a curing catalyst. Preferably, the compound is resin powder containing e.g. styrene as the component B, a material swelling by absorbing styrene as the component D and >=50wt.% of at least one kind of monomer unit selected from among an acrylate, a methacrylate and an aromatic vinyl compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-strength sheet molding compound. More specifically, the present invention relates to a high-strength sheet molding compound which uses a glass fiber woven fabric as a reinforcing material, can be molded at low temperature and low pressure, and does not cause foaming during molding.

[0002]

2. Description of the Related Art In recent years, reinforced plastics (FRP), which is based on unsaturated polyester resin and contains a reinforcing material such as glass fiber, has mechanical strength and is lightweight, so that it is widely used in daily life products, industrial equipment and the like. It is used. Among them, especially leisure applications such as boats and skateboards, transportation applications such as containers and truck parts,
In applications such as helmets and military civil engineering applications where a large external force is applied but lightweight is preferred, the advent of reinforced plastics with even higher strength has been desired. FRP whose strength per unit weight is stronger than iron
Must have a high glass fiber content as a reinforcing material such as roving cloth, glass cloth, filament mat, chopped strand mat. In order to obtain an unsaturated polyester resin molded article having such a high strength, a hand lay-up method has conventionally been required in the vapor of monomer and the scattering of glass fiber pieces. That is, it is necessary to impregnate the glass fiber layer with a liquid resin composition having appropriate thixotropy and good fluidity. However, the hand lay-up method requires skill, labor costs are low due to low productivity, and there is a problem that the work environment is likely to be poor. On the contrary, without requiring skill,
The sheet molding compound method is a processing method of unsaturated polyester resin that has high productivity and does not deteriorate the working environment. A conventional sheet molding compound is an unsaturated polyester resin composition prepared by mixing a mixture of an unsaturated polyester resin and a liquid polymerizable monomer with a filler, a thickener, a colorant, a release agent, a curing catalyst and the like. By applying it to a film with a doctor blade, cutting glass roving on it and scattering it, sandwiching it with a film coated with an unsaturated polyester resin composition, pressing with a roller, impregnation, defoaming, and winding. Manufactured.
40 ~ rolled sheet molding compound
The film is thickened by aging at 50 ° C. to make the film peelable and then used for molding. Molding is often performed by compression molding using a mold at a high temperature and high pressure of a heating temperature of 120 to 180 ° C. and a pressing force of 30 to 100 kg / cm ² . As the thickener, an oxide of an alkaline earth metal such as magnesium oxide is generally used. However, the thickening effect is insufficient only with magnesium oxide, and therefore it is necessary to add a large amount of filler. The unsaturated polyester resin composition in which a large amount of the filler is added and the thickener is blended in this way has poor impregnability into the glass fiber layer, and therefore the introduction of the glass fiber as a reinforcing material cuts the roving. And then spraying it onto the unsaturated polyester resin composition applied to the release film. The compounding amount is 40 parts per 100 parts by weight of the unsaturated polyester resin and the liquid polymerizable monomer.
Since the upper limit is about parts by weight, it is difficult to obtain a high-strength molded article containing a large amount of reinforcing material. In addition, when the molding temperature is high like the standard processing conditions of the conventional sheet molding compound, when the glass fiber woven fabric is used as the fiber reinforcement, the phenomenon that the air remaining in the glass fiber woven fabric is heated and foams occurs. However, there is a problem that a good molded product cannot be obtained.

[0003]

DISCLOSURE OF THE INVENTION The present invention uses a glass fiber woven fabric as a reinforcing material and enables low-temperature low-pressure molding,
The purpose of the present invention is to provide a high-strength sheet molding compound that does not cause foaming during molding.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that by blending an unsaturated polyester resin with a thermoplastic resin powder as a thickener, It is not necessary to mix the earth metal-based thickener and the inorganic filler into the sheet molding compound, and the unsaturated polyester resin composition can be impregnated into the reinforcement even when the high-density glass fiber woven fabric is used as the reinforcement. It was found that the sheet molding compound can be formed, and further, the sheet molding compound can be formed at low temperature and low pressure, and the present invention has been completed based on this finding. That is,
The present invention provides (1) 30 to 120 parts by weight of (B) liquid polymerizable monomer, per 100 parts by weight of (A) unsaturated polyester resin,
Unsaturation containing (C) 40 to 180 parts by weight of glass fiber woven fabric, (D) 20 to 120 parts by weight of a thickener made of thermoplastic resin powder, and (E) 0.5 to 7 parts by weight of a curing catalyst. Polyester resin High-strength sheet molding compound and (2) High-strength sheet molding compound described in item (1) are placed in a mold, heated to 40 to 120 ° C., and unsaturated polyester resin to be molded by pressurizing at low pressure. A method for molding a strong sheet molding compound is provided. Furthermore, as a preferred embodiment of the present invention, (3) the liquid polymerizable monomer is styrene, and the thermoplastic resin powder absorbs and swells styrene. 4) Item (1), wherein the thermoplastic resin powder is a resin powder containing 50% by weight or more of at least one monomer unit selected from acrylic acid ester, methacrylic acid ester and aromatic vinyl compound. Alternatively, the high-strength sheet molding compound according to item (3), (5) the thermoplastic resin powder has (a) a glass transition point of −30.
Radical polymerization having a core portion composed of an acrylic acid ester-based or methacrylic acid ester-based polymer and / or a diene-based polymer at a temperature of ℃ or below, and (b) an acrylic acid ester-based or methacrylic acid ester-based monomer and a free carboxyl group Core / shell type copolymer particles composed of a shell layer composed of a copolymer having a glass transition point of 70 ° C. or higher with a water-soluble unsaturated carboxylic acid monomer and ion-crosslinked with a metal cation. High-strength sheet molding compound according to item (1), (3) or (4), which is a polymer resin powder, (6) item (1), item (3), item (4) A high-strength sheet molding in which the high-strength sheet molding compound according to item (5) is installed on the lower die surface, and the sheet molding compound is pressed by the upper die at a low pressure of 0.1 to 10 kg / cm ² (gauge pressure). De (7) Item (1), Item (3), Item (4) or Item (5) of the high-strength sheet molding compound is placed on the mold surface and covered with a film. -760 between mold surface and film
Molding method for high-strength sheet molding compound, wherein pressure is reduced to -50 mmHg and the sheet molding compound is pressurized at a low pressure by the pressure difference from the atmospheric pressure, (8) Item (1), Item (3), Item (4) Item or the high-strength sheet molding compound according to item (5) is placed on the mold surface and covered with a film, and the sheet molding compound is pressurized at a low pressure by applying an air pressure of 1 to 5 kg / cm ² (gauge pressure) to the film. Examples include a method for molding a high-strength sheet molding compound, and a high-strength sheet molding compound molded article molded by the method described in (9) (6), (7) or (8).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The high-strength sheet molding compound of the present invention comprises (A) unsaturated polyester resin 1
30 to 12 (B) liquid polymerizable monomer per 100 parts by weight
0 parts by weight, (C) 40 to 180 parts by weight of glass fiber woven fabric,
(D) 20 to 120 parts by weight of a thickener composed of a thermoplastic resin powder and (E) 0.5 to 7 parts by weight of a curing catalyst. In the present invention, the unsaturated polyester resin used as the component (A) is not particularly limited, and a known unsaturated polyester resin conventionally used for a general unsaturated polyester resin molded article can be used. The unsaturated polyester resin is obtained from an unsaturated polybasic acid or an unsaturated polybasic acid optionally containing a saturated polybasic acid and a polyhydric alcohol. Examples of unsaturated polybasic acids include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, chloromaleic acid, and dialkyl esters thereof. These unsaturated polybasic acids can be used alone or in combination of two or more. Examples of the saturated polybasic acid that replaces part of the unsaturated polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, het acid, hexahydrophthalic anhydride, adipic acid, sebacic acid, and azelaic acid. And so on. These saturated polybasic acids can be used alone or in combination of two or more. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol and 1,2-pentane. Diol, 1,6-hexanediol, cyclohexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerin monoallyl ether, hydrogenated bisphenol A, 2,2-bis (4
-Hydroxyethoxyphenyl) propane, 2,2-bis
Examples thereof include diols such as (4-hydroxypropoxyphenyl) propane, triols such as trimethylolpropane, and tetraols such as pentaerythritol. These polyhydric alcohols can be used alone or in combination of two or more.

When an oxide of an alkaline earth metal which has been conventionally used as a thickener is used, the number average molecular weight of the unsaturated polyester resin as the component (A) is about 2,500.
It was necessary to be 0 or more, but in the sheet molding compound using the thermoplastic resin powder used in the present invention as a thickening agent, the number average molecular weight is 1,000 to 2,500.
Since the unsaturated polyester resin can be used as a sheet molding compound, the usable molecular weight range is expanded. In the present invention, the unsaturated polyester resin as the component (A) is, if necessary, an epoxy acrylate resin for improving chemical resistance, or a urethane acrylate resin for improving adhesiveness in insert processing or the like. Can be partially replaced with. Examples of the epoxy acrylate resin used for such a purpose include those obtained by adding acrylic acid or methacrylic acid to bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin and the like. be able to.
As the urethane acrylate resin, for example, JP-B-55-30527 and JP-B-60-26132.
Examples of the ethylene glycol disclosed in JP-B No. 60-26133 and JP-B No. 60-26133 have tolylene diisocyanate added to both ends, and 2-hydroxyethyl methacrylate added to both ends. In the sheet molding compound of the present invention, the unsaturated polyester resin is usually used in a state of being dissolved in the liquid polymerizable monomer as the component (B). The liquid polymerizable monomer used as the component (B) can be used without particular limitation as long as it has solubility in an unsaturated polyester resin and has radical polymerizability. Methacrylic acid esters, aromatic vinyl compounds and allyl alcohol esters of aromatic carboxylic acids can be used particularly preferably. The liquid polymerizable monomer causes a crosslinking reaction with the unsaturated polyester resin as the component (A) during molding.

Examples of acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate. , 2-ethylhexyl acrylate, n-octyl acrylate, and the like, and examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, and cyclohexyl. Methacrylate, 2-
Examples thereof include ethylhexyl methacrylate, n-octyl methacrylate, diethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, vinyltoluene,
Examples thereof include t-butylstyrene, α-chlorostyrene, dichlorostyrene, divinylbenzene and the like.
Examples of the allyl alcohol ester of aromatic carboxylic acid include diallyl phthalate, diallyl isophthalate and triallyl trimellitate. Of these liquid polymerizable monomers, styrene can be particularly preferably used. In the present invention, the liquid polymerizable monomer as the component (B) may be used alone or in combination of two or more. The blending amount is 30 to 120 parts by weight, preferably 40 to 100 parts by weight, per 100 parts by weight of the unsaturated polyester resin as the component (A). When the amount of the liquid polymerizable monomer is less than 30 parts by weight per 100 parts by weight of the unsaturated polyester resin, the viscosity of the composition is high and it may be difficult to produce a sheet molding compound. When the compounding amount of the liquid polymerizable monomer exceeds 120 parts by weight per 100 parts by weight of the unsaturated polyester resin, the final molded product tends to be brittle.

The sheet molding compound of the present invention contains a glass fiber woven fabric as the component (C). Examples of the glass fiber woven fabric include roving cloth and glass cloth. The roving cloth is a plain weave thick cloth woven by roving having 8 to 60 aligned rovings. The glass cloth is a thin cloth obtained by weaving a yarn in which a strand is twisted to a predetermined thickness. In the present invention, a plain weave, a twill weave, a satin weave, a one-way weave or the like can be used. In the present invention, the glass fiber woven fabric,
The component (A) is contained in an amount of 40 to 180 parts by weight, preferably 60 to 120 parts by weight, per 100 parts by weight of the unsaturated polyester resin. If the content of the glass fiber woven fabric is less than 40 parts by weight per 100 parts by weight of the unsaturated polyester resin, the molded product may not have sufficiently high strength. If the content of the glass fiber woven fabric exceeds 180 parts by weight per 100 parts by weight of the unsaturated polyester resin, it may be difficult to impregnate the glass fiber woven fabric with the unsaturated polyester resin composition. The sheet molding compound of the present invention contains a thermoplastic resin powder as a component (D) as a thickener. As the thermoplastic resin powder,
There is no particular limitation as long as it absorbs the liquid polymerizable monomer (B) and swells, but at least one monomer selected from acrylic acid esters, methacrylic acid esters and aromatic vinyl compounds is used. It is preferable to use a thermoplastic resin powder containing 50% by weight or more of a monomer unit. Examples of the acrylic acid ester used as a raw material monomer of the thermoplastic resin powder include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl. Acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate,
Examples thereof include n-octyl acrylate, and examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, and 2-ethylhexyl methacrylate. , N-octyl methacrylate and the like. Of these monomers, methyl methacrylate is particularly suitable. Further, as the aromatic vinyl compound,
For example, styrene, α-methylstyrene, divinylbenzene and benzene nuclei of these monomers, a methyl group, an ethyl group, a propyl group, a monomer such as butyl group is substituted, for example, vinyltoluene and isobutylstyrene Can be mentioned. These monomers may be used alone or in combination of two or more. When the content of the acrylic acid ester, methacrylic acid ester or aromatic vinyl compound monomer unit in the thermoplastic resin powder is less than 50% by weight, the thermoplastic resin powder may not show a sufficient thickening effect. There is.

The thermoplastic resin powder as the component (D) may contain another monomer unit copolymerizable with the above-mentioned monomer, and as the other copolymerizable monomer, , For example, vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl esters such as vinyl acetate, vinyl propionate, vinyl myristate, vinyl oleate, vinyl benzoate; acrylic acid, methacrylic acid, 2-ethylpropenoic acid , Unsaturated acids such as crotonic acid, cinnamic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid; monomethyl maleate, monoethyl maleate, monobutyl itaconic acid, etc. Monoesters of saturated dicarboxylic acids; butadiene, isoprene, 1,3-pentadiene, cyclopenta Conjugated diene compounds such as ene;
Examples include non-conjugated diene compounds such as 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene and the like. Furthermore, in order to adjust the solubility when the thermoplastic resin powder is used as a thickening agent in the process of producing a sheet molding compound of an unsaturated polyester resin composition, the polymer constituting the thermoplastic resin powder is appropriately used. It can be crosslinked. Examples of the copolymerization component for giving a crosslinked structure include glycidyl (meth) acrylate, 3,4-epoxycyclohexyl (meth) acrylate, 2-aminoethyl (meth) acrylate, and 3-aminoethyl (meth) acrylate.
Aminopropyl (meth) acrylate, 2-aminobutyl
(Meth) acrylate, (meth) acrylamide, N-2-
Aminoethyl (meth) acrylamide, N-2-aminopropyl (meth) acrylamide, N-3-aminopropyl
(Meth) acrylamide, polyethylene glycol dimethacrylate having 1 to 14 ethylene groups, trimethylolpropane trimethacrylate, triallyl trimellitate, diallyl phthalate, allyl glycidyl ether,
Mention may be made of monomers such as triallyl isocyanurate. The other copolymerizable monomers may be used alone or in combination of two or more.

Further, for the purpose of suppressing the thickening of the sheet molding compound of the present invention with time, it is possible to ionically crosslink between the polymers on the surface of the thermoplastic resin powder particles.
The ionic crosslinking can be formed by adding a metal cation to the thermoplastic resin powder particles having a carboxyl group on the surface to crosslink between the carboxyl groups. Ion crosslinking has the effect of suppressing the penetration of the solvent into the thermoplastic resin powder particles, but unlike the crosslinking structure by covalent bonding, it dissociates due to an increase in molecular momentum at high temperatures, so there is no crosslinking during molding. Does not behave like a polymer. The thermoplastic resin powder as the component (D) exerts an effect as a thickener in the sheet molding compound, and is mixed with the liquid polymerizable monomer as the component (B) to form the liquid polymerizable monomer. Is absorbed and swelled so that the sheet molding compound exhibits a controlled and good processing viscosity within a predetermined temperature. Therefore, in addition to the selection of the above-mentioned suitable composition, it is preferable to have an appropriate particle diameter and particle surface state. For particle size,
The average single particle diameter is preferably 0.2 to 40 μm, more preferably 0.5 to 15 μm. If the average single particle size is less than 0.2 μm, the absorption rate of the liquid polymerizable monomer at room temperature is too high and the viscosity becomes too high, which makes it difficult to mix and impregnate the fiber reinforcement. There is a risk. If the average single particle diameter exceeds 40 μm, the absorption rate of the liquid polymerizable monomer at room temperature becomes low, and pseudo-curing may be slow, making it difficult to produce a sheet molding compound. Here, pseudo-curing refers to the property of absorbing a liquid component and swelling to form a gel. However, when the fiber reinforcement is blended in an amount of 30 parts by weight or more per 100 parts by weight of the unsaturated polyester resin, the thermoplastic resin powder has an average single content in order to uniformly blend the fiber reinforcement as a low-viscosity blend. The particle size is preferably 1 to 40 μm, but after mixing with the fiber reinforcement, a thermoplastic resin having a small particle size of about 0.2 to 5 μm appears in order to exhibit an increase in viscosity suitable for the sheet molding compound. It is more preferable to use the powder in combination with a thermoplastic resin powder having a larger particle size, for example, a particle size of about 50 μm so that the average particle size of the powder is 1 to 40 μm. Further, the shape of the thermoplastic resin powder is preferably spherical. If the compound having an irregular shape has a high viscosity when blended, only a small amount can be added, and if it is a small amount, it is tacky and does not exhibit a pseudo-curing phenomenon, so that it is difficult to produce a sheet molding compound. The surface condition of the particles is preferably smooth rather than porous in terms of viscosity control.

The degree of absorption and swelling property of the liquid polymerizable monomer to be contained in the thermoplastic resin powder as the component (D) is preferably such that the sheet molding compound exhibits a specific viscosity and storage stability. That is, in the present invention, the viscosity (measured at 25 ° C.) at a point of time of 24 hours at 40 ° C. after the preparation of the unsaturated polyester resin composition before the addition of the component (C) glass fiber fabric is 1,000 to 50,00
The viscosity (measured at 25 ° C.) at 0 Pa · s after 30 days at 30 ° C. after preparation is preferably 5 times or less than the viscosity at 24 hours at 40 ° C. after preparation. After the preparation of the unsaturated polyester resin composition, 2 at 40 ° C
Viscosity after 4 hours (measured at 25 ° C) is 1.0
If it is less than 00 Pa · s or more than 50,000 Pa · s, it may be difficult to produce a sheet molding compound. If the viscosity at 30 ° C. for 30 days after preparation exceeds 5 times the viscosity at 40 ° C. for 24 hours after preparation, the storage stability of the sheet molding compound decreases and the flexibility May decrease, making handling and molding difficult. In addition,
When measuring the viscosity, the condition is adjusted by placing it in a thermostat at 25 ° C. for 1 hour, and then the viscosity is measured in an environment of 25 ° C. and relative humidity of 60%. In the present invention, the thermoplastic resin powder of the component (D) has a weight average degree of polymerization of 1,000 to 150,000.
It is preferably 0. Weight average degree of polymerization is 1,000
If it is less than 150,000 or more than 150,000, it may be difficult to produce a sheet molding compound having an appropriate viscosity behavior. When the thermoplastic resin powder is polymerized by adding a crosslinking monomer, if the degree of crosslinking is too high, the sheet molding compound formation time may be prolonged. The crosslinking degree of the thermoplastic resin powder is preferably about 50% by weight or less of the insoluble gel component when the thermoplastic resin powder is dissolved in the solvent. The method for producing such a thermoplastic resin powder is not particularly limited, and is a method conventionally used for producing a fine resin powder such as polyvinyl chloride or polymethylmethacrylate, for example, a fine suspension polymerization method or an emulsion polymerization method. , A seeded emulsion polymerization method, a suspension polymerization method and the like can be adopted. Among these methods, a spherical shape having an average single particle diameter of 0.1 to 5 μm without particularly fine particle diameter is used. Polymerization methods that give the following are preferred. For example, as a fine suspension polymerization method, an oil-soluble initiator is used as a radical polymerization initiator, and the particle diameter of the monomer oil droplets is preliminarily subjected to a homogenization treatment to control the droplet diameter before the initiation of polymerization, thereby performing homogeneous dispersion polymerization. A method and the like are suitable.

The thermoplastic resin powder as the component (D) can have a core / shell type structure having a polymer having the above composition in the shell layer. The core component has a glass transition point −
A (meth) acrylic acid ester-based polymer and / or a diene-based polymer having a temperature of 30 ° C. or lower, preferably −40 ° C. or lower, is preferable because the mechanical strength and elastic modulus of the molded article are significantly improved. In order to produce such thermoplastic resin powder particles of the core / shell type copolymer, first, the glass transition point of the core portion is -30 ° C by emulsion polymerization or fine suspension polymerization.
A rubber-like seed polymer (a) made of the following polymer is prepared. Examples of the polymer having a glass transition point of −30 ° C. or lower include (meth) acrylic acid ester-based polymers and diene-based polymers. In the present invention, (meta)
Acrylic acid ester means acrylic acid ester or methacrylic acid ester. Examples of the (meth) acrylic acid ester-based monomer that gives a homopolymer having a glass transition point of −30 ° C. or lower include, for example, n-propyl acrylate (glass transition point of homopolymer −52 ° C.), n−
Butyl acrylate (the same -54 ° C), n-octyl acrylate (the same -65 ° C), 2-ethylhexyl acrylate (the same -85 ° C), n-decyl methacrylate (the same-).
65 ° C.) and the like, and one of these may be used, or two or more thereof may be used in combination. Particularly, n-butyl acrylate and 2-ethylhexyl acrylate are preferable. Examples of the diene-based monomer that gives a homopolymer having a glass transition point of −30 ° C. or lower include butadiene, isoprene, 1,3-pentadiene,
Conjugated diene compounds such as cyclopentadiene; 1,4
-Non-conjugated diene compounds such as hexadiene may be mentioned, and these may be used alone or in combination of two or more. Among these, butadiene and isoprene are particularly preferable. In the present invention, the above
(Meth) acrylic acid ester-based or diene-based monomer, optionally by adding a cross-linking monomer such as ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, a core having further rubber elasticity It is also effective to prepare parts.

Next, the thus obtained polymer having a glass transition point of -30 ° C or lower is used as a core portion (a), and a shell layer (b) made of a copolymer having a glass transition point of 70 ° C or higher. To form. As the raw material component of the shell layer used at this time, it is desirable to mainly use a monomer that gives a homopolymer having a glass transition point of 70 ° C. or higher. Specifically, for example,
Isopropyl methacrylate (homopolymer glass transition point 81 ° C.), t-butyl methacrylate (107
C), cyclohexyl methacrylate (76 ° C.), phenyl methacrylate (110 ° C.), methyl methacrylate (105 ° C.), etc. (meth) acrylic acid ester type monomers; styrene (100 ° C.), 4-chlorostyrene (At 110 ° C), 2-ethylstyrene (at 103 ° C)
Aromatic vinyl monomers such as; acrylonitrile (12
5 ° C.), vinyl chloride (at the same temperature of 80 ° C.) and the like. One of these monomers can be used, and 2
More than one species can be used in combination. Of these, (meth) acrylic acid ester-based monomers, particularly methyl methacrylate, are preferable. The glass transition point of the shell layer (b) is preferably 70 ° C. or higher, more preferably 90 ° C. or higher. The glass transition point of the shell layer is 70
When the temperature is lower than 0 ° C, when the thermoplastic resin powder particles made of the core / shell type copolymer are dried after the polymerization reaction, they tend to aggregate to form a lump. Further, the weight ratio of the core part / shell layer is 1
It is preferably in the range of / 4 to 3/1, preferably 1/3 to 2/1. When the weight ratio of the core portion / shell layer is less than 1/4, the function as a thickener, a moldability improver in low temperature / low pressure molding, a reinforcing material, etc. in the sheet molding compound of the thermoplastic resin powder deteriorates. There is a risk. If the weight ratio of the core part / shell layer exceeds 3/1, the viscosity stability of the sheet molding compound may be reduced.

In the present invention, the metal cation as a cross-linking agent forms an ionic cross-link between a carboxyl group and a carboxyl group introduced as a side chain into the shell layer of the core / shell type copolymer. The three-dimensional polymer structure reduces the swelling property of the unsaturated polyester resin and the liquid polymerizable monomer at room temperature as a dispersion medium, but the unsaturated polyester resin and the liquid polymerizable monomer are heated to form a core / shell structure. Since it hardens while penetrating into the mold copolymer, the original performance can be exhibited. In the present invention, the thermoplastic resin powder as the component (D) is 20 parts by weight per 100 parts by weight of the unsaturated polyester resin as the component (A).
To 120 parts by weight, preferably 25 to 100 parts by weight, and more preferably 30 to 90 parts by weight. The blending amount of the thermoplastic resin powder is the unsaturated polyester resin 10
When it is less than 20 parts by weight per 0 parts by weight, the viscosity is low,
It may be difficult to manufacture the sheet molding compound. When the blending amount of the thermoplastic resin powder exceeds 120 parts by weight per 100 parts by weight of the unsaturated polyester resin, the viscosity becomes too high and it may be difficult to impregnate the glass fiber woven fabric. The sheet molding compound of the present invention contains a curing catalyst as the component (E). The curing catalyst decomposes by heating to generate radicals, and crosslinks and polymerizes the liquid polymerizable monomer of the component (B) with the unsaturated polyester resin of the component (A) to cure the entire composition. Is to have. The curing catalyst can be appropriately selected depending on the temperature used for forming the sheet molding compound, and examples thereof include t-butylperoxybenzoate, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, and t-butyl peroxide. Oxy-2-ethylhexanoate, di-t-butylhydroperoxide, lauroyl peroxide, 1,1-di-t-butylperoxy-3,
Examples thereof include organic peroxides such as 5,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, and bis (4-t-butylcyclohexyl) peroxycarbonate. If necessary, a curing stabilizer can be used in combination with a curing catalyst. Examples of such a curing stabilizer include hydroquinone, naphthoquinone, t-butylcatechol and the like. Only one curing catalyst can be used, or two or more curing catalysts can be used in combination.
The compounding amount of the curing catalyst is 0.5 to 7 parts by weight, and more preferably 1 to 5 parts by weight, per 100 parts by weight of the unsaturated polyester resin as the component (A). The amount of the curing catalyst added is 0.5 per 100 parts by weight of the unsaturated polyester resin.
If the amount is less than part by weight, curing during molding may be insufficient. If the compounding amount of the curing catalyst exceeds 7 parts by weight per 100 parts by weight of the unsaturated polyester resin, the storage stability of the sheet molding compound may decrease.

In the sheet molding compound of the present invention, as long as the object of the present invention is not impaired, various additives conventionally used in the sheet molding compound, such as an internal release agent, a shrinkage reducing agent and a coloring agent, are used. , An antifoaming agent, a viscosity reducing agent and the like can be blended as necessary. The sheet molding compound of the present invention usually contains an internal release agent. The internal release agent used is not particularly limited, and known internal release agents for unsaturated polyester resins, for example, higher fatty acids such as stearic acid, higher fatty acid salts such as zinc stearate and calcium stearate, and alkyl phosphates. Ester, wax, etc. can be mentioned. Among these, zinc stearate has good mold release properties and excellent surface gloss of molded products, so
It can be particularly preferably used. Internal release agent is (A)
To 100 parts by weight of the unsaturated polyester resin as a component,
0.5 to 10 parts by weight, preferably 2 to 6 parts by weight is blended. If it is less than 0.5 part by weight, it may be difficult to release the mold, and if it exceeds 10 parts by weight, it may be deposited on the surface of the molded product to cause blooming. Examples of the shrinking agent include thermoplastic resins such as polystyrene, polyethylene, polymethyl methacrylate, polyvinyl chloride, polyvinyl acetate, polycaprolactam, saturated polyester, styrene-acrylonitrile copolymer, polybutadiene, polyisoprene, and styrene. Examples thereof include rubbery polymers such as a butadiene copolymer and an acrylonitrile-butadiene copolymer. The purpose of the addition of these shrinkage reducing agents is usually 4 to 10 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin. In that respect, when the thermoplastic resin powder is used as the thickener in the present invention, 2
If the amount is 0 to 120 parts by weight, the effect will not be exhibited, and thus the amount will be significantly different. Further, the above-mentioned thermoplastic resin or rubber-like polymer may be dissolved in styrene, methyl methacrylate, ethyl acrylate or the like and used as a liquid.
In the sheet molding compound of the present invention, since the thermoplastic resin powder is used as the thickener, it is possible to form the sheet molding compound without necessarily blending the inorganic filler, and as a result,
The flowability during molding of the sheet molding compound is improved, and the transparency and coloring of the molded product are also excellent. However, a filler may be added within a range that does not impair the effects of the present invention, for fine adjustment of viscosity or as an extender for cost reduction. As the inorganic filler added in such a case, for example, calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, clay, celite, asbestos, barlite, baryta, silica, silica sand, dolomite limestone, Gypsum, aluminum fine powder, hollow balloons, alumina, glass powder, aluminum hydroxide, cryolite, zirconium oxide, antimony trioxide, titanium oxide, molybdenum dioxide and the like can be mentioned. These inorganic fillers are appropriately selected in consideration of workability, strength, appearance, and economical efficiency of the obtained molded product, but calcium carbonate or aluminum hydroxide is usually used.

The sheet molding compound of the present invention can be prepared in a manner similar to conventional sheet molding compounds. FIG. 1 is an explanatory view showing one aspect of a manufacturing process of a sheet molding compound. In order to produce the sheet molding compound of the present invention, the unsaturated polyester resin of the component (A) is dissolved in advance in the liquid polymerizable monomer of the component (B), and then, for example, a planetary mixer, a kneader, Using a known mixer such as a disperser, the thermoplastic resin powder of the component (D) and the curing catalyst of the component (E) are added and sufficiently stirred and mixed to homogenize. The unsaturated polyester resin composition 2 prepared by the mixer 1 is transferred to a coater bank of an SMC machine, and one or both of the two release films 3 is coated with a coater 4 to a constant thickness of 0.3 to 3 mm. Then
On one of the applied unsaturated polyester resin composition
The (C) component glass fiber woven fabrics 5 are laminated and then laminated with the coated surface inside and rolled by a rolling mill 6 to a thickness of 0.5 to 5 m.
A sheet of m is obtained, and the sheet is wound by the take-up roller 7 with both sides covered with a release film. The sheet molding compound of the present invention is a thermoplastic resin powder that absorbs and swells a liquid polymerizable monomer, instead of an oxide of an alkaline earth metal that has been conventionally used as a thickener for a conventional sheet molding compound. , Is mixed with an unsaturated polyester resin. The viscosity of the unsaturated polyester resin composition can be adjusted by selecting the thermoplastic resin powder, and the viscosity before adding the glass fiber fabric can be controlled to 4 to 10 Pa · s. . As a result, it becomes possible to produce a sheet molding compound obtained by impregnating a high-density glass fiber woven fabric or the like with an unsaturated polyester resin composition, which could not be conventionally used for a sheet molding compound, and further increase the viscosity after impregnation. When using a catalyst that cures at 100 ° C. or higher, the temperature is 1,000 to 5,000 Pa in a few hours by heating to about 50 ° C. and aging.
-It can have a viscosity of s. Further, since the initial viscosity of the unsaturated polyester resin composition can be suppressed, it is possible to prevent bubbles from being mixed when the glass fiber fabric is impregnated. Since magnesium oxide acts as an accelerator for low-temperature activated curing catalyst, it is not possible to use low-temperature activated catalysts in conventional sheet molding compounds that use magnesium oxide as a thickener. It was an obstacle to molding. Since the sheet molding compound of the present invention does not use magnesium oxide, it can be molded at a low temperature and can be easily molded at 80 to 90 ° C. Therefore, even a sheet molding compound using a high density glass fiber woven fabric or the like can be used. It does not cause the foaming phenomenon. As a result, the flexibility of the material of the mold by low temperature and low pressure processing is expanded, it becomes possible to mold the sheet molding compound even with the resin mold, and at the same time, a high-strength cured molded product that could not be obtained by the conventional processing of the sheet molding compound. Can be obtained.

Since the sheet molding compound of the present invention has a high temperature dependency of the viscosity at the time of molding, it is particularly excellent in fluidity at the time of heating and pressurizing, and for example, at room temperature, it is 5,000 to 8,000 Pa. A sheet molding compound with a viscosity of 10 s
The viscosity is up to 30 Pa · s, a complicated mold surface can be reproduced, heating deaeration can be performed at a low pressure, and a cured molded product free of air bubbles can be easily obtained. The sheet molding compound of the present invention is capable of low-temperature and low-pressure molding, so without using expensive equipment or mold,
A molded product having a beautiful appearance can be obtained. The sheet molding compound of the present invention has a molding temperature of 40.
Molding pressure is 0.1-10kg / c in compression molding at ~ 120 ℃
It can be molded with m ² (gauge pressure). Molding time is
Molding is usually possible in 1 to 10 minutes. Furthermore, a sheet molding compound is installed on the mold surface, and a polypropylene sheet or an upper mold is closed on the sheet molding compound, and then the system is degassed to bring the sheet molding compound into close contact with the (lower) mold, and the atmospheric pressure. A molding method (hereinafter referred to as vacuum molding) in which a sheet molding compound is brought into close contact with a mold by a force of a differential pressure in the mold to form a shape is a molding temperature 4
0-120 ℃, -760--50mmHg (0-710Tor
It can be performed under the pressure of r). In addition, a sheet molding compound is installed on the mold surface, and the pressure molding is performed by pressing the sheet molding compound against the mold surface with pressurized air to bring it into close contact, at a molding temperature of 40 to 120 ° C. and a pressure of 1 to 1.
It can be performed at 5 kg / cm ² (gauge pressure). By using the sheet molding compound of the present invention, it is possible to obtain a high-strength sheet molding compound molded product by eliminating the restrictions of conventional large-scale equipment under high temperature and high pressure and expensive molds. Conventionally, it has been extremely difficult to perform molding at a low temperature and a low pressure as described above using a sheet molding compound. However, since the sheet molding compound of the present invention is shaped by being softened at a low temperature and a low pressure, according to the present invention, it is possible to stack the sheet molding compound, for example, about 2 to 10 sheets. A molded product can be obtained. The hardness of the sheet molding compound of the present invention does not change much even when stored for a long time, and the mold shape can be sufficiently reproduced by low pressure molding, vacuum or pressure molding, and a low temperature decomposition type curing agent is used. Even in this case, the long-term storage stability of the sheet molding compound at room temperature will be sufficient. Even in the low pressure molding, it is not necessary to adjust the viscosity such as reducing the amount of glass fiber mixed.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 The molar ratio of propylene glycol / neopentyl glycol / isophthalic acid / fumaric acid is 15/35/20/30.
100 parts by weight of an unsaturated polyester resin composed of a random copolymer having a number average molecular weight of 3,300 is added to 43 parts by weight of styrene and uniformly dissolved to obtain an average single particle size of 1.9.
Polymethylmethacrylate resin powder having a particle size of 30,000 and a weight average degree of polymerization of 30,000
0] 29 parts by weight, zinc stearate [Sakai Chemical Industry Co., Ltd.,
SZ-2000] 4 parts by weight, t-butylperoxy-2
-Ethyl hexanoate [NOF CORPORATION, Percure O] 3 parts by weight and bis-4-t-butylcyclohexyl peroxydicarbonate [Kayaku Akzo Co., Ltd., Percadox 16] 1.5 parts by weight, The mixture was mixed at room temperature to obtain an unsaturated polyester resin composition. The viscosity of this unsaturated polyester resin composition after being stored at 40 ° C. for 24 hours was measured by a rotational viscometer (HAAKE, Rheo Stress).
s RS-100 type) was 3400 Pa · s when measured at 25 ° C. Using an SMC machine, a polypropylene film as a release film was coated with the above unsaturated polyester resin composition to a thickness of 2 mm, and a glass fiber roving cloth [Nitto Boseki Co., Ltd., WR800B
-100] were laminated, and sandwiched between polypropylene films coated with an unsaturated polyester resin composition to a thickness of 2 mm. The amount of glass fiber roving cloth is the amount of unsaturated polyester resin 1 in the unsaturated polyester resin composition.
It is 100 parts by weight per 00 parts by weight. A glass fiber roving cloth between two polypropylene films was impregnated with an unsaturated polyester resin composition by a rolling mill,
It was wound up to obtain a sheet molding compound. This sheet molding compound at 40 ° C for 24 hours
When the polypropylene film was peeled off after aging for a period of time, the sheet molding compound was not sticky at all, and it was easily peeled off, and no adhesion of the sheet molding compound component to the film was observed. 30
90 compression mold with 0mm x 300mm satin finish
The sheet molding compound was kept at 0 ° C. and cut into 300 mm × 300 mm, three sheet molding compounds were laminated and placed on the mold surface, and compression molding was performed for 10 minutes by applying a pressure of 5 kg / cm ^{2 to} the mold. The matte finish of the mold was beautifully transferred to the surface of the molded product, and a sheet molding compound molded product with a good appearance was obtained. A test piece is cut out from this molded product and JIS K
According to 6911, the bending strength in the direction in which the roving cloth surface is parallel to the load direction was measured to be 5,4.
It was 00 kg / cm ² . Comparative Example 1 Unsaturated polyester resin 1 same as that used in Example 1
00 parts by weight, styrene 43 parts by weight, polymethylmethacrylate resin powder 29 parts by weight, zinc stearate 4 parts by weight, t-butylperoxy-2-ethylhexanoate 3 parts by weight and bis-4-t-butylcyclohexylper. A sheet molding compound was prepared by using 1.5 parts by weight of oxydicarbonate and 143 parts by weight of calcium carbonate [NS-100] manufactured by Nitto Koka Kogyo Co., Ltd. to prepare an unsaturated polyester resin composition. In addition, this unsaturated polyester resin composition is
When the viscosity after storage for a period of time was measured in the same manner as in Example 1, it was 3,400 Pa · s. Using an SMC machine, a polypropylene film as a release film is coated with the above unsaturated polyester resin composition in a thickness of 2 mm, and a glass fiber roving having a diameter of 13 μm [Nitto Boseki
Co., Ltd.] was cut into a cut length of 1 inch and scattered, and then sandwiched between polypropylene films coated with an unsaturated polyester resin composition in a thickness of 2 mm. The amount of glass fiber sprayed is
It is 43 parts by weight per 100 parts by weight of the unsaturated polyester resin in the unsaturated polyester resin composition. The glass fiber between the two polypropylene films was impregnated with the unsaturated polyester resin composition and wound to obtain a sheet molding compound. After the sheet molding compound was cured at 40 ° C. for 24 hours and then the polypropylene film was peeled off, the sheet molding compound was not sticky at all, and it was easily peeled off and adhesion of the sheet molding compound to the film was not observed. Keep a compression molding die with a satin surface of 300 mm × 300 mm at 90 ° C, 300 mm × 30
3 sheets of sheet molding compound cut to 0 mm
The sheets were stacked and placed on the surface of the mold, and compression molding was performed by applying a pressure of 5 kg / cm ^{2 to} the mold for 10 minutes. The matte finish of the mold was beautifully transferred to the surface of the molded product, and a sheet molding compound molded product with a good appearance was obtained. A test piece was cut out from this molded product and the bending strength was measured according to JIS K 6911, and it was 2,800 kg / cm ² . Comparative Example 2 Unsaturated Polyester Resin 1 Same as that Used in Example 1
00 parts by weight, styrene 43 parts by weight, magnesium oxide [Kyowa Chemical Co., Ltd., MgO # 40] 4 parts by weight, calcium carbonate [Nitto Koka Kogyo KK, NS-100] 214 parts by weight, zinc stearate [Sakai Chemical Industry Co., Ltd., SZ-200
0] 4 parts by weight, t-butylperoxy-2-ethylhexanoate [NOF CORPORATION, Percure O] 3 parts by weight, and bis-4-t-butylcyclohexyl peroxydicarbonate [Kayaku Akzo Co., Ltd. ), Perkadox 16]
1,5 parts by weight were mixed at room temperature to obtain an unsaturated polyester resin composition. The viscosity of this unsaturated polyester resin composition after being stored at 40 ° C. for 24 hours was measured as in Example 1.
It was 3,800 Pa · s when measured in the same manner as. Using an SMC machine, a polypropylene film as a release film is coated with the above unsaturated polyester resin composition in a thickness of 2 mm, and a glass fiber roving having a diameter of 13 μm [Nitto Boseki Co., Ltd.] is cut into a cut length of 1 inch. Then, the unsaturated polyester resin composition was sandwiched between polypropylene films having a thickness of 2 mm. The amount of the glass fiber sprayed is 57 parts by weight per 100 parts by weight of the unsaturated polyester resin in the unsaturated polyester resin composition. The glass fiber between the two polypropylene films was impregnated with the unsaturated polyester resin composition and wound to obtain a sheet molding compound. After the sheet molding compound was cured at 40 ° C. for 24 hours and the polypropylene film was peeled off, the sheet molding compound was not sticky at all and easily peeled off, but a small amount of the sheet molding compound component was attached to the film. 300 mm x 3
Keep the compression molding die having a matte surface of 00 mm at 90 ° C., stack 3 sheet molding compounds cut into 300 mm × 300 mm, place them on the die surface, and place 5 on the die.
Compression molding was carried out for 10 minutes by applying a pressure of kg / cm ² . The molded product was not sufficiently cured, and the matte surface of the mold was not transferred to the surface of the molded product. Comparative Example 3 The same unsaturated polyester resin 1 as that used in Example 1
00 parts by weight, styrene 43 parts by weight, magnesium oxide [Kyowa Chemical Co., Ltd., MgO # 40] 4 parts by weight, calcium carbonate [Nitto Koka Kogyo KK, NS-100] 143 parts by weight, zinc stearate [Sakai Chemical Industry Co., Ltd., SZ-200
0] 4 parts by weight, t-butylperoxy-2-ethylhexanoate [NOF CORPORATION, Percure O] 3 parts by weight, and bis-4-t-butylcyclohexyl peroxydicarbonate [Kayaku Akzo Co., Ltd. ), Perkadox 16]
1.5 parts by weight were mixed at room temperature to obtain an unsaturated polyester resin composition. The viscosity of this unsaturated polyester resin composition after being stored at 40 ° C. for 24 hours was measured as in Example 1.
It was 2,700 Pa · s when measured in the same manner as. Using an SMC machine, a polypropylene film as a release film was coated with the above unsaturated polyester resin composition to a thickness of 2 mm, and one glass fiber roving cloth [Nitto Boseki Co., Ltd., WR800B-100] was laminated, Further, the unsaturated polyester resin composition was sandwiched between polypropylene films having a thickness of 2 mm. The amount of glass fiber roving cloth is 3 per 100 parts by weight of the unsaturated polyester resin in the unsaturated polyester resin composition.
3 parts by weight. Attempting to impregnate the unsaturated polyester resin composition into the glass fiber roving cloth between the two polypropylene films with an SMC machine rolling machine, the glass fiber roving cloth was completely impregnated with the unsaturated polyester resin composition. I couldn't let you do it. The results of Example 1 and Comparative Examples 1 to 3 are collectively shown in Table 1.

[0019]

[Table 1]

[Note] 1) Unsaturated polyester resin: propylene glycol /
Neopentyl glycol / isophthalic acid / fumaric acid = 1
5/35/20/30 mol% random copolymer, number average molecular weight 3,300. 2) Glass fiber fabric: roving cloth WR800B-
100, manufactured by Nitto Boseki Co., Ltd. 3) Glass fiber: diameter 13 μm, manufactured by Nitto Boseki Co., Ltd. 4) Thermoplastic resin powder: Zeon F-320, polymethylmethacrylate resin powder, average single particle size of 1.9 μm, weight average degree of polymerization of 30,000, manufactured by Zeon Corporation. 5) Magnesium oxide: MgO # 40, Kyowa Chemical Co., Ltd.
Made. 6) Calcium carbonate: NS-100, Nitto Koka Kogyo Co., Ltd.
Made. 7) Zinc stearate: SZ-2000, Sakai Chemical Industry
Co., Ltd. 8) Curing catalyst 1: Percure O, t-butylperoxy-2-ethylhexanoate, half-life of 65 ° C. × 24 hours, manufactured by NOF Corporation. 9) Curing catalyst 2: Perkadox 16, bis-4-t
-Butylcyclohexyl peroxydicarbonate, half-life 40 ° C x 10 hours, manufactured by Kayaku Akzo Co., Ltd. The sheet molding compound of Example 1 of the present invention has a good film peeling property after 24 hours, and can be molded at a low temperature and a low pressure of a molding temperature of 90 ° C. and a molding pressure of 5 kg / cm ² , and is cured and molded. The product has a high bending strength of 5,400 kg / cm ² . On the other hand, the sheet molding compound of Comparative Example 1 in which the roving cut as the glass fiber is used and calcium carbonate is mixed as the filler has good film peeling property and low-temperature / low-pressure moldability, The bending strength is lower than that of the cured molded article of Example 1 using roving cloth. The sheet molding compound of Comparative Example 2 in which magnesium oxide was used as the thickening agent and cut roving was used as the reinforcing material without compounding the thermoplastic resin powder could not be molded. Furthermore, in Comparative Example 3 in which magnesium oxide was used as the thickening agent and roving cloth was used as the reinforcing material without blending the thermoplastic resin powder, the roving cloth could not be impregnated with the unsaturated polyester resin composition. It was

[0021]

EFFECTS OF THE INVENTION The high-strength sheet molding compound of the present invention uses a high-density glass fiber woven fabric as a reinforcing material, so that it can be molded at low temperature and low pressure even though it has high strength, and bubbles are generated in the molded product. A beautiful molded product can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of one embodiment of a manufacturing process of a sheet molding compound.

[Explanation of symbols]

 1 Mixer 2 Unsaturated Polyester Resin Composition 3 Release Film 4 Coater 5 Glass Fiber Woven Fabric 6 Rolling Machine 7 Winding Roller

Claims (2)

[Claims] 1. (A) 30 to 120 parts by weight of liquid polymerizable monomer, (C) 40 to 180 parts by weight of glass fiber woven fabric, and (D) per 100 parts by weight of unsaturated polyester resin.
An unsaturated polyester resin high-strength sheet molding compound comprising 20 to 120 parts by weight of a thickener made of a thermoplastic resin powder and (E) 0.5 to 7 parts by weight of a curing catalyst. 2. A high-strength sheet molding compound according to claim 1 is placed in a mold and heated to 40 to 120 ° C.,
Unsaturated polyester resin high-strength sheet molding compound molding method by pressurizing at low pressure.