JPH0995519A - Method for molding unsaturated polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a form of stable quality simply by a low-temperature low- pressure pressurized bag system by using a sheet molding compound comprising a specified unsaturated polyester resin composition. SOLUTION: A sheet molding compound(SMC) comprising an unsaturated polyester resin composition containing an unsaturated polyester resin, a thickener containing a thermoplastic resin powder as an effective component, a liquid polymerizable monomer, a curing agent and a reinforcement is laid on the inside surface of the first forming mold 1 with its inside surface coinciding with the contour of the aimed form such as a boat or a bathtub, a bag 4 made of an elastic material is placed on the SMC layer 3, the first forming mold 1 is covered with the second forming mold or a pressure-resistant plate 2, and the bag 4 is pressurized with a fluid (e.g. a gas or a liquid such as air, steam or water) at 40-100 deg.C to a pressure of 0.1-10kgf/cm<2> (at gauge) to closely press the inflated bag 4 against the upper surface of the SMC layer 3 and to thereby obtain a form.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel method for molding an unsaturated polyester resin composition. More specifically, the present invention relates to a molding method performed at low temperature and low pressure using a sheet molding compound (hereinafter, abbreviated as SMC) obtained by thickening in a short time.

[0002]

2. Description of the Related Art In recent years, SMC based on unsaturated polyester resin has been used in the reinforced plastics processing industry.
It has been steadily growing in demand as a new industrial material for machine forming, which incorporates demands for labor saving, mass production, and improvement of working environment. SMC is generally used as a thickening agent (sheeting agent) in a liquid dispersion prepared by mixing an unsaturated polyester resin, a liquid polymerizable monomer, a curing agent, an inorganic filler, a release agent, a flame retardant, a pigment and the like. A composition containing an alkaline earth metal oxide or hydroxide and further containing about 20 to 50 parts by weight of a reinforcing material such as glass fiber per 100 parts by weight of the liquid dispersion in order to impart toughness. , A sheet made by sandwiching a release film to increase the viscosity with time. This sheet is further moved to a molding site, usually laminated and laid in a mold, and heat-molded to obtain a molded product having a final shape. At this time, the molding is usually 100 to 18
The pressing is performed under the conditions of 0 ° C., high temperature and high pressure of 30 to 100 kgf / cm ² (gauge pressure). Since a molded product obtained by curing causes a volume shrinkage of about 7 to 10%, a thermoplastic resin is added as a low shrinking agent as a method for improving the shrinkage (Japanese Patent Publication No. 46-14541).
JP-A-6-32809). In this way, molding technology was improved and unsaturated polyester resin was used more, but the mold that withstands high pressure is expensive,
In addition, various high-temperature and high-pressure facilities are also restricted, and they cannot be widely applied to small-quantity products or large-scale products.

Therefore, at low temperature (40 to 100 ° C.) and /
Alternatively, a method of molding an unsaturated polyester resin that can be molded at a low pressure (0.1 to 10 kgf / cm ² ) has been investigated.
For example, when molding at a low temperature, a low-temperature decomposition type curing agent is adopted, and when molding at a low pressure, the amount of metal oxide or inorganic hydroxide added as a filler or flame retardant,
Alternatively, the composition was adjusted such that the mixing ratio of the glass fiber used as the reinforcing material was reduced to lower the viscosity of the SMC during heating. However, the low-temperature decomposition type curing agent used for producing the SMC capable of low-temperature molding reacts with an oxide of an alkaline earth metal added as a thickener to facilitate the production of SMC. As it accelerates curing, press molding in a short time, or
Or it was necessary to store the SMC at low temperature until it was molded. If an attempt is made to reduce the amount of an alkaline earth metal oxide or the like in order to solve such a problem, various problems described below occur. That is, for example, in the case of low pressure molding, it is necessary to reduce the amount of alkaline earth metal oxide so that the unsaturated polyester resin composition flows at a low pressure, but in that case, the viscosity increase of SMC becomes insufficient. Therefore, the release film sandwiching the SMC sheet is difficult to peel off. Therefore, a complicated operation of molding with the release film attached and removing the release film after the molding is required. Moreover, since it is formed with a release film, it is difficult to laminate a plurality of SMC sheets to form a thick product. Also,
If there is a small amount of alkaline earth metal oxides,
Since the reaction with the curing agent continues to proceed slowly at room temperature, SM
Storage stability of C was poor, and it was inevitable that the period of use was limited. Similarly, if an attempt is made to reduce the amount of glass fibers mixed in for the purpose of lowering the viscosity, the strength of the resulting molded article will decrease.

As a molding method of the unsaturated polyester resin at a low temperature and / or a low pressure, there is a method of using an inexpensive mold material such as a hand lay-up method and a spray-up method.
These are not suitable for stable mass production because the quality of the molded product is unstable depending on the skill of the worker and the working environment in which the vapor of the polymerizable monomer and the fine powder of the glass fiber can enter. In addition, in the conventional method of forming a pressure bag using an unsaturated polyester resin, a low pressure of several kgf / cm ² (gauge pressure) or less can be applied due to the restriction of the material of the bag, so that a liquid type It could be molded only by using the saturated polyester resin composition. Therefore, the vapor from the organic liquid drifts and the working environment is deteriorated, and a method for improvement has been awaited. In recent years, the appearance of unsaturated polyester resin compositions has made it possible to perform molding at low and medium pressures using SMC, and to pursue high quality and high productivity. However, a press molding machine for aligning the upper mold (first mold) and the lower mold (second mold) has a problem of high equipment cost, and development of a simple pressure molding method has been desired. .

[0005]

Under the circumstances, the present invention uses an SMC which can be produced in a short time and has good storage stability, and which has a good release film peeling property. Thus, the present invention has been made for the purpose of providing a method for molding an unsaturated polyester resin that can be performed at low temperature and low pressure.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to develop a method for molding an unsaturated polyester resin at low temperature and low pressure, the alkaline earth metals conventionally used as thickeners have been conventionally used. Instead of a metal oxide, etc., a fine powder of a specific thermoplastic resin having a composition and particle size capable of forming a good processing viscosity is used. It was found that a composition having a specific viscosity behavior when blended with a polyester resin has excellent fluidity and moldability at low temperature and low pressure, and can be pressed with a pressure bag, and based on this finding, the present invention Has been completed. That is, the present invention provides (1) (A) unsaturated polyester resin, (B) thickener containing thermoplastic resin powder as an active ingredient, (C) liquid polymerizable monomer, (D) curing agent, and ( E) A sheet molding compound made of an unsaturated polyester resin composition containing a reinforcing material is laid inside a first mold, and then a bag made of an elastic material is placed and covered with a second mold or a pressure plate. From the bag with a fluid at 40 to 100 ° C. for 0.1 to 10 kgf / cm
² (gauge pressure) pressurizing method for unsaturated polyester resin, and (2) (A) unsaturated polyester resin, (B) thickener containing thermoplastic resin powder as an active ingredient, A sheet molding compound composed of an unsaturated polyester resin composition containing (C) a liquid polymerizable monomer, (D) a curing agent, and (E) a reinforcing material is laid inside a first molding die, and then an elastic material. Is placed on the sheet and is covered with a second mold or pressure plate, and a space formed by the sheet and the second mold or pressure plate is 40
A method for molding an unsaturated polyester resin, which comprises pressurizing to 0.1 to 10 kgf / cm ² (gauge pressure) with a fluid at -100 ° C.

In the composition used in the present invention, (A)
The unsaturated polyester resin used as a component is not particularly limited, and a known unsaturated polyester resin that has been conventionally used for general unsaturated polyester resin molded products can be used. This unsaturated polyester resin is obtained from an α, β-unsaturated carboxylic acid or an α, β-unsaturated carboxylic acid optionally containing a saturated carboxylic acid and an alcohol. Examples of α, β-unsaturated carboxylic acids include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, chloromaleic acid, and dimethyl esters thereof. These α, β-unsaturated carboxylic acids may be used alone or in combination of two or more. Further, as the saturated carboxylic acid,
Examples thereof include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, het acid, hexahydrophthalic anhydride, adipic acid, sebacic acid, and azelaic acid.
These saturated carboxylic acids may be used alone or in combination of two or more. On the other hand, as the alcohol, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,6-hexane. Diol, cyclohexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerin monoallyl ether, hydrogenated bisphenol A, 2,2-bis (4-hydroxypropoxyphenyl) propane, 2,
Examples thereof include diols such as 2-bis (4-hydroxyethoxyphenyl) propane, triols such as trimethylolpropane, and tetraols such as pentaerythritol. These alcohols may be used alone or in combination of two or more.

When an alkaline earth metal oxide or the like conventionally used as a thickener for producing SMC is used, the molecular weight of the unsaturated polyester resin as the component (A) is about 2,500. It had to be above. However, in the present invention, by using a thickener containing a thermoplastic resin powder as an active ingredient, even an unsaturated polyester resin having a molecular weight of 1,000 to 2,500 can have a sufficiently high viscosity, so that an SMC can be obtained. Is. In this case, SMC
The fluidity of the sheet during heat molding is particularly excellent, and molding at low pressure becomes possible.

In the present invention, the unsaturated polyester resin as the component (A) may be an epoxy acrylate resin for improving chemical resistance, or a urethane acrylate for improving adhesiveness during insert processing. A portion of the resin can be replaced. Examples of the epoxy acrylate resin used for such a purpose include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin,
Examples thereof include a novolac type epoxy resin and the like to which acrylic acid or methacrylic acid is added. Further, as the urethane acrylate resin, for example, Japanese Patent Publication Sho 55
No. 30527, Japanese Patent Publication No. 60-26132 and Japanese Patent Publication No. 60-26133, tolylene diisocyanate is added to both ends of ethylene glycol, and 2-hydroxyethyl methacrylate is further added to both ends. And so on. Usually, the unsaturated polyester resin is used in a state of being dissolved in the liquid polymerizable monomer as the component (C).

In the present invention, the thickener containing the thermoplastic resin powder used as the component (B) as an active ingredient is at least one selected from the group consisting of acrylic acid esters, methacrylic acid esters and aromatic vinyl compounds. A resin powder containing 50% by weight or more of a monomer unit is preferable. If the content is less than 50% by weight, the object of the present invention may not be sufficiently achieved. Examples of the acrylic acid ester 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, etc. are mentioned, and as the methacrylic acid ester, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2
-Ethylhexyl methacrylate, n-octyl methacrylate and the like can be mentioned. Of these, ethyl acrylate and methyl methacrylate are preferable. Also,
As the aromatic vinyl compound, styrene, α-methylstyrene, divinylbenzene and benzene nucleus of these monomers, a monomer in which a methyl group, an ethyl group, a propyl group, a butyl group or the like is substituted, for example, vinyl. Examples include toluene and isobutyl styrene. Of these, styrene is preferred. The monomer may be used alone,
Two or more kinds may be used in combination.

Next, the resin powder of the component (B) is 50
Other copolymerizable monomer units may be contained in a proportion of less than wt%, and examples of the other copolymerizable monomer include 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,
Unsaturated monocarboxylic acids such as 2-ethylpropenoic acid, crotonic acid, cinnamic acid; unsaturated polycarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, chloromaleic acid; monomethyl maleate, monoethyl maleate, Monoesters of unsaturated polycarboxylic acids such as monobutyl itaconate; butadiene, isoprene, 1,
Conjugated diene compounds such as 3-pentadiene and cyclopentadiene; and non-conjugated diene compounds such as 1,4-hexadiene, dicyclopentadiene and ethylidene norbornene. Further, in order to adjust the solubility when the resin is used as a thickener, the polymer constituting the resin may be appropriately crosslinked. It is also possible to adjust the viscosity increase by this crosslinking. Examples of monomers for this crosslinking include glycidyl (meth) acrylate, 3,4-epoxycyclohexyl (meth) acrylate, 2-aminoethyl (meth) acrylate, 3-aminopropyl (meth) acrylate, and 2-aminobutyl. (Meth) acrylate, (meth) acrylamide, N-2-aminoethyl (meth) acrylamide, N-2-aminopropyl (meth) acrylamide, N-3-aminopropyl (meth)
Examples of the monomer include acrylamide, polyethylene glycol dimethacrylate having 1 to 14 ethylene groups, trimethylolpropane trimethacrylate, triallyl trimellitate, diallyl phthalate, allyl glycidyl ether, and triallyl isocyanurate. The above-mentioned other copolymerizable monomers may be used alone or in combination of two or more. Further, for the purpose of controlling the viscosity increase of the unsaturated polyester resin composition used in the present invention, the polymers on the surface of the resin particles may be ionically crosslinked. The ionic cross-linking is, for example, adding a metal cation to resin particles having a polymer containing a carboxyl group on the surface to cross-link between the carboxyl groups. While ionic cross-linking has the effect of suppressing the penetration of solvent into the resin particles, unlike the cross-linking structure by covalent bonds, it dissociates due to the increase in molecular motion at high temperatures, so there is no cross-linking of the polymer during molding. It is possible to behave.

The resin powder of the component (B) is used as a thickener for SMC preparation, and absorbs and swells the component (C) by mixing with the liquid polymerizable monomer (C) component.
The unsaturated polyester resin composition exhibits a controlled and good processing viscosity within a predetermined temperature of 50 ° C. or lower. For that purpose, in addition to the selection of the above-mentioned suitable composition, it is preferable to have an appropriate particle diameter, particle shape and surface state. Regarding the particle size, the average single particle size is preferably in the range of 0.2 to 40 μm. If the average single particle size is less than 0.2 μm, it is too fine and the absorption rate of the liquid polymerizable monomer as the component (C) at room temperature is fast, and the viscosity becomes too high in a short time to mix glass fibers and the like. It gets harder. When the average single particle size exceeds 40 μm,
Since the specific surface area of the particles becomes small, the amount necessary to obtain sufficient thickening may become excessive and the strength of the molded product may be reduced. When a reinforcing material such as glass fiber is blended in an amount of 30 parts by weight or more per 100 parts by weight of the component (A), the reinforcing material cannot be uniformly added unless the viscosity is kept low for a certain period of time. On the other hand, after mixing the reinforcing agent, it is necessary to raise the viscosity to a value suitable for SMC. In such a case, before the reinforcement is added, for example, a large resin powder of about 50 μm is mainly used, and after the reinforcement is added, a resin powder having a small particle size of about 0.2 to 5 μm can be added. However, the selection of the particle size is based on the weight-based average particle size of 1 to 40μ.
It is preferable to set it to m. The shape of the resin powder is preferably spherical. If an irregular shape is blended, the viscosity will be too high, so only a small amount can be added, and if it is a small amount, it will be tacky and will not exhibit a pseudo-curing phenomenon.
The peelability of the release film when using MC is reduced. It is desirable that the surface condition of the particles be smooth, similarly in terms of viscosity control. The thickening effect may be influenced by the kind and amount of the surfactant and the dispersant as the polymerization auxiliary material attached to the surface.

The degree of absorption and swellability of the liquid polymerizable monomer that the thermoplastic resin powder (B) should have is preferably such that the unsaturated polyester resin composition exhibits a specific viscosity and storage stability. That is, the composition used in the present invention is
Viscosity (25
(Measured in ° C) is preferably 1 to 50 million cps. If it deviates from this range, it will be difficult to manufacture an SMC. Also, after measuring the viscosity at the time of composition preparation, 30 ° C
Viscosity after 30 days (measured at 25 ° C)
However, it is preferable that the viscosity is 5 times or less of the viscosity at the time point when 24 hours have passed. If it exceeds 5 times, the storage stability of the SMC-made sheet deteriorates, the flexibility decreases, and it becomes difficult to handle and mold after aging. Thermoplastic resin powder (B)
That only absorbs the liquid polymerizable monomer and does not swell,
Alternatively, if the degree of swelling is small, the viscosity of the composition becomes low and the above-mentioned specific value is not exhibited, which is not preferable.

The resin powder of component (B) preferably has a weight average degree of polymerization of 1,000 to 150,000. When the weight average degree of polymerization deviates from the above range, it is difficult to form an SMC having the above viscosity behavior. Further, when the resin powder is copolymerized by adding the above-mentioned crosslinkable monomer and the degree of crosslinking is too high, the SMC sheet formation time becomes long. The degree of cross-linking is preferably about 50% by weight or less of the insoluble gel component when the resin powder is dissolved in a solvent.

There is no particular limitation on the method for producing such a resin powder, and any 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 weight method. Although a method such as a seeding method, a seed emulsion polymerization method, and a suspension polymerization method can be adopted, among these methods, a polymerization method that can obtain a spherical particle without particularly fine particle diameter is preferable. . For example, fine suspension polymerization, that is, an oil-soluble initiator is used as a radical polymerization initiator, and the particle diameter of the monomer oil droplets is homogenized before the initiation of polymerization to adjust the droplet diameter in advance to carry out homogeneous dispersion polymerization. The method is suitable as a polymerization method for obtaining particles having an average single particle diameter of about 0.2 to 5 μm. Examples of the oil-soluble radical polymerization initiator include dibenzoyl peroxide, di-3,5,5-trimethylhexanoyl peroxide,
Organic peroxides such as diisopropyl peroxydicarbonate; azo compounds such as 2,2'-azobisisobutyronitrile can be used. These catalysts may be used either individually or in combination of two or more. The amount used is appropriately selected depending on the type and amount of the monomer, the charging system, etc., but is usually used per 100 parts by weight of the monomer. , 0.001 to 5.0 parts by weight can be selected. Further, in this fine suspension polymerization method or suspension polymerization method, a surfactant or a dispersant is usually used. Examples of the surfactant include anionic surfactants such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and sodium dihexylsulfosuccinate; sorbitan monooleate, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers. Nonionic surfactants such as; cationic surfactants such as cetylpyridinium chloride and cetyltrimethylammonium bromide. Examples of the dispersant include polyvinyl alcohol, methyl cellulose, polyvinylpyrrolidone and the like. These may be used alone or in combination of two or more.
0.05 to 5 parts by weight, preferably 0.
It can be appropriately selected within a range of 2 to 4.0 parts by weight.
For example, in the case of the fine suspension polymerization method, first, in an aqueous medium, an oil-soluble catalyst, a monomer, a surfactant, and a polymerization aid such as higher fatty acids and higher alcohols which are optionally used, The additive is added and premixed and homogenized with a homogenizer to adjust the particle size of oil droplets.
Examples of the homogenizer include a colloid mill, a vibration stirrer, a two-stage high pressure pump, a high pressure jet from a nozzle or an orifice, and ultrasonic stirring. Furthermore, the control of oil droplet size is influenced by the control of shear force during homogenization, the stirring conditions during polymerization, the type of reactor, the amount of surfactants and additives, etc., but these are simple. By appropriate preliminary experiments, appropriate conditions can be selected.

On the other hand, also in the suspension polymerization method, an oil-soluble initiator is used as a radical polymerization initiator, and usually an aqueous solution prepared by previously dissolving the above-mentioned dispersant or, if necessary, a combination of the above-mentioned surfactants. In the medium, heating while controlling the size of the droplet particles of the monomer with a stirrer having a predetermined shearing force, to obtain a spherical polymer particles by polymerization reaction, the particle size at this time, Usually 5 to 80 on average
It is in the range of μm. After the completion of the polymerization reaction, the slurry containing the produced polymer particles is centrifugally filtered, and the polymer is taken out as a powder through a fluidized bed drying furnace. The molecular weight (weight average degree of polymerization) of this polymer can be adjusted to a desired value by the reaction temperature and the molecular weight modifier.

The thermoplastic resin powder (B) may have a core / shell structure having a polymer having the above composition in a shell layer. In particular, when the core component is a (meth) acrylic acid ester-based polymer and / or a diene-based polymer having a glass transition point of −30 ° C. or lower, preferably −40 ° C. or lower, the mechanical strength and elastic modulus of the molded article are improved. It is preferable because it greatly improves. In the present invention, the resin powder of component (B) is
The amount is preferably 20 to 120 parts by weight, more preferably 25 to 100 parts by weight, and further preferably 30 to 90 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin as the component (A). If the blending amount is less than 20 parts by weight, the viscosity of the composition tends to be low and SMC tends to be difficult to prepare, and if it exceeds 120 parts by weight, the viscosity becomes too high and mixing of glass fibers and the like may be difficult. is there.

In the present invention, a liquid polymerizable monomer is added as the component (C). The monomer is a liquid at ordinary temperature and pressure, which is also usually used as a solvent for the unsaturated polyester resin (A). The preferred component (C) is at least one liquid polymerizable monomer selected from acrylic acid esters, methacrylic acid esters, aromatic vinyl compounds and aromatic allyl compounds.
The liquid polymerizable monomer causes a crosslinking reaction with the unsaturated polyester resin of the component (A) by the curing agent of the component (D) during processing. Examples of the acrylic ester 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-
Examples thereof include ethylhexyl acrylate and n-octyl acrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate,
Examples thereof include n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, diethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.
Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, α-chlorostyrene, dichlorostyrene, divinylbenzene and the like. As the aromatic allyl compound, diallyl phthalate, diallyl isophthalate, triallyl trimellitate and the like can be used. Among these liquid polymerizable monomers, aromatic vinyl compounds, especially styrene, are preferable. The liquid polymerizable monomer as the component (C) may be used alone or in combination of two or more, and the blending amount thereof is the unsaturated polyester resin 100 as the component (A). 30 to 120 parts by weight is preferable, and more preferably 4 parts by weight.
It is selected in the range of 0 to 100 parts by weight. This amount is 30
If it is less than 100 parts by weight, the viscosity of the composition will be high, making it difficult to prepare SMC, and if it exceeds 120 parts by weight, the final molded article tends to be brittle.

In the present invention, a curing agent is used as the component (D). This curing agent decomposes by heating or the like to generate radicals, and crosslinks and polymerizes the liquid polymerizable monomer of the component (C) with the unsaturated polyester resin of the component (A) to form the entire composition. It has a curing effect. Specific examples thereof include t-butyl peroxybenzoate, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butyl peroxy-2-ethylhexanoate, di-t-butyl hydroperoxide, lauroyl peroxide. Oxide, 1,1-
Examples thereof include organic peroxides such as di-t-butylperoxy-3,5,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, and bis (4-t-butylcyclohexyl) peroxycarbonate. If desired, a curing stabilizer may be used in combination with the curing agent, and examples of the curing stabilizer include hydroquinone, naphthoquinone, t-butylcatechol and the like. The curing agent as the component (D) may be used alone or in combination of two or more, and the compounding amount thereof is 0. 100 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin as the component (A). The amount is preferably 1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. If the amount is less than 0.1 part by weight, curing at the time of molding may be insufficient, and if it exceeds 5 parts by weight, the storage stability of the composition may decrease. Examples of the reinforcing material of the component (E) include glass fiber, polyester fiber, phenol fiber, polyvinyl alcohol fiber,
Aromatic polyamide fiber (Kevlar fiber, trade name manufactured by DuPont), nylon fiber, carbon fiber, and other FRP (Fi
berReinforcedPlastics). Examples of the form of these reinforcing materials include chopped strands, chopped strand mats, rovings, and woven fabrics. These reinforcing materials are appropriately selected in consideration of the viscosity of the composition and the strength of the resulting molded product.

The unsaturated polyester resin composition comprising the components (A), (B), (C) and (D) is added to the reinforcing material (E).
By adding the components, a polyester resin molding material capable of giving a molded product having sufficient mechanical strength can be obtained. The length of chopped strands is usually 5 to 60 mm. When the shorter one is heated, the molding material tends to flow, but the mechanical strength of the molded product decreases. In the present invention, as long as the object of the present invention is not impaired, various additives conventionally used in unsaturated polyester resin compositions for SMC, such as a low-contracting agent, an inorganic filler, and a release agent, are added. , Can be blended as desired. Examples of the shrinkage reducing agent include polystyrene, polyethylene, polymethyl methacrylate, polyvinyl chloride,
Polyvinyl acetate, polycaprolactam, saturated polyester, thermoplastic resins such as styrene-acrylonitrile copolymer, polybutadiene, polyisoprene, styrene-
Examples thereof include rubber-like polymers such as butadiene copolymer and acrylonitrile-butadiene copolymer. The amount of the shrinkage reducing agent added is 100% of the unsaturated polyester resin.
It is usually 4 to 10 parts by weight with respect to parts by weight, and usually (C).
It is used as a solution by adding it to the liquid polymerizable monomer as a component.

As the inorganic filler, 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, economy of the obtained molded product, but usually calcium carbonate or aluminum hydroxide is often used. Conventional SMC agent (thickener)
When an oxide or hydroxide of an alkaline earth metal, which has been commonly used as the above, is used, it is difficult to obtain a sufficient thickening effect only with the SMC agent, and therefore the unsaturated component of the component (A) is usually used. 1 to 100 parts by weight of polyester resin
It was necessary to use a large amount of an inorganic filler such as calcium carbonate of about 100 parts by weight in combination. However, when the thickener containing the thermoplastic resin powder according to the present invention as an active ingredient is used, it is possible to form SMC without these inorganic fillers, and as a result, it is possible to form SMC sheets by heat molding. The fluidity is improved, and the transparency and coloring of the molded product are also excellent. Examples of the release agent include higher fatty acids such as stearic acid, higher fatty acid salts such as zinc stearate,
Alternatively, alkyl phosphate ester and the like can be mentioned. This release agent is usually used in a proportion of 0.5 to 5 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin as the component (A). In addition to these, a curing accelerator, a coloring agent, a defoaming agent, a viscosity reducing agent and the like can be used if necessary.

The unsaturated polyester resin composition used in the present invention can be prepared by the same procedure as the conventional unsaturated polyester resin composition, or can be prepared by a unique procedure. In order to prepare the unsaturated polyester resin composition used in the present invention by the conventional method, the unsaturated polyester resin (A) is previously dissolved in all or part of the liquid polymerizable monomer (C), and then, For example, using a known mixer such as a planetary mixer, a kneader, or a disper, the remaining components (B), (C), (D), etc. are collectively stirred and sufficiently mixed. Next, the reinforcing material of the component (E) is added, and the addition site is usually the above (A),
This is before the step of rolling the mixture of the components (B), (C) and (D) in the SMC machine. This is because if the reinforcing material is mixed from the beginning, the viscosity of the composition becomes too high and it becomes difficult to roll it into a sheet. As a unique method of preparing SMC according to the present invention, a method of adding resin powder of a thickener before, after, or simultaneously with addition of a reinforcing material can be adopted. That is, after the components (A), (C) and (D) are mixed in a mixer, when the mixture is subjected to the rolling step of the SMC machine, the components (B) and (E) are mixed before or after, or It is added at the same time and rolled. According to this method, the unsaturated polyester resin prepared by the mixer, the initial mixture containing the liquid polymerizable monomer and the curing agent,
Since there is almost no increase in viscosity, there is no time restriction that the SMC must be immediately produced following the conventional mixing. Therefore, if a curing agent having a 10-hour half-life of 80 ° C. or higher is used, it can be used for several weeks. On the other hand, the initial mixture of the original adjusting method of the present invention having a low viscosity is easy to apply on the release film because the reinforcing material is not mixed, and yet the thickener resin powder and the reinforcing material are applied on the coated surface. If it is sprayed, it is easily dispersed in the applied mixture and the viscosity of the coating layer rises rapidly. Therefore, by rolling this, an SMC having a desired semi-hard property can be immediately produced. it can.

The method of the present invention will be described with reference to FIGS. In the present invention, the above SMC capable of low temperature and low pressure molding is used to perform the molding process in the pressure bag system. In the pressure bag system, for example, an SMC is laid on the inner surface of a first molding die 1 (often a lower die) having an outer surface shape of a molding object such as a boat or a bathtub, and an elastic material is formed on the SMC layer 3. Bag 4 (also called pressure bag) or sheet 6
(Also referred to as a pressure sheet) is placed, and then the cover-like pressure plate 2 having the air supply pipe 7 is covered, and then the bag 4 is pressurized. Alternatively, the space formed by the sheet 6 and the pressure plate 2 is pressed.
A second mold (often an upper mold, not shown) can be used in place of the pressure plate. In that case, it is also possible to lay the SMC on the inner surface of the second mold. The above-mentioned pressurizing method uses a fluid at 40 to 100 ° C., that is, a gas or liquid such as air, steam, and water, at 0.1 to 10 kgf / cm.
^With the pressure of ² (gauge pressure), the expanded bag 4 or sheet 6 is brought into close contact with the upper surface of the SMC layer 3 and pressed. This smoothes the surface of the SMC layer 3 and
Can be made uniform in thickness. It is preferable to interpose a release film 8 made of, for example, polyolefin between the bag 4 or the sheet 6 and the SMC layer 3 because the bag or sheet can be easily peeled off from the SMC layer after molding. The pressure bag or pressure sheet is made of a stretchable elastic material such as natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, isoprene rubber, chloroprene rubber, silicone rubber, polyurethane, polyamide. Is. The thickness of the pressure bag or the pressure sheet is appropriately selected in consideration of the size and shape of the molding die, elasticity and rigidity of the elastic material, and the like.

The molding pressure in the present invention, that is, the pressure of the pressure bag or the pressure of the space formed by the pressure sheet and the pressure plate or the second molding die is 0.1 to 10 kgf / cm.
² (gauge pressure), preferably 1 to 5 kgf / cm ² (gauge pressure). If it is less than 0.1 kgf / cm ² , the pressing force is too weak and the smoothness of the surface of the SMC layer decreases, or the wall thickness of the vertical portion becomes excessively thick at the lower part. Also, 1
Even if it is higher than 0 kgf / cm ² , there is no effect corresponding to the applied energy, and the bag is easily damaged. The pressure is 3 kgf / c so that air bubbles do not stand out in the resin layer of the molded product.
It is preferable that the pressure is at least m ² (gauge pressure). It is also effective to apply a gel coat in advance to the inner surface of the molding die as a method for preventing bubbles from being mixed into the surface of the molded product in contact with the molding die. The molding temperature in the present invention is 40 to 100.
C., preferably 60 to 80.degree. If it is lower than 40 ° C, the viscosity of SMC is too high and the fidelity of the mold surface of the molded product is lowered, and if it is higher than 100 ° C, the bag and the molding die are easily damaged.
According to the present invention, a fluid such as heated air, steam, or water is passed through the pressure bag or through the space formed by the pressure sheet and the pressure plate or the second mold, so that heat is directly transmitted to the SMC. However, it has the advantage of good thermal efficiency. Molding of unsaturated polyester resin by the pressure bag method has been conventionally performed, but it is a high viscosity of unsaturated polyester resin mixed with liquid polymerizable monomer while applying a glass fiber mat to the inner surface of the mold. The solution was applied while being impregnated with the solution to form a resin coating layer, and then heated at 100 to 180 ° C. for molding. That is, it has a bad working environment as seen in the hand lay-up method and the like, and also has a problem in terms of quality that uneven thickness often occurs due to the flow-down of the resin coating layer. In the present invention, the work of pasting the SMC sheet on the inner surface of the molding die is sufficient, and the thickness can be adjusted by laminating 2 to 15 sheets, and the problems of the work surface and quality can be solved. In addition, it was possible to reduce energy consumption due to a decrease in heating temperature and good thermal efficiency.

The aspects of the present invention will be described below. (1) Containing (A) unsaturated polyester resin, (B) thickener containing thermoplastic resin powder as an active ingredient, (C) liquid polymerizable monomer, (D) curing agent and (E) reinforcing material The sheet molding compound composed of the unsaturated polyester resin composition is laid inside the first molding die, and then a bag made of an elastic material is placed, and the bag is covered with the second molding die or the pressure plate, and the 0.1 at 100 ° C fluid
A method for molding an unsaturated polyester resin, which comprises pressurizing to 10 kgf / cm ² (gauge pressure). (2) Thickener 2 containing (B) thermoplastic resin powder as an active ingredient per 100 parts by weight of (A) unsaturated polyester resin
0 to 120 parts by weight, (C) liquid polymerizable monomer 30 to 12
A sheet molding compound made of an unsaturated polyester resin composition containing 0 parts by weight, (D) a curing agent and (E) a reinforcing material is laid inside the first mold, and then a bag made of an elastic material is placed, A method for molding an unsaturated polyester resin, which comprises covering with a second molding die or a pressure plate and then pressurizing the bag with a fluid at 40 to 100 ° C. to 0.1 to 10 kgf / cm ² (gauge pressure). (3) Containing (A) unsaturated polyester resin, (B) thickening agent containing thermoplastic resin powder as an active ingredient, (C) liquid polymerizable monomer, (D) curing agent and (E) reinforcing material A sheet molding compound composed of the unsaturated polyester resin composition is laid inside the first mold, and then a sheet composed of an elastic material is placed, and then covered with the second mold or pressure plate, and then the sheet and the The space formed by the second mold or the pressure plate is filled with a fluid of 40 to 100 ° C. for 0.1 to 10
A method for molding an unsaturated polyester resin, which comprises pressurizing to kgf / cm ² (gauge pressure). (4) Thickener 2 containing (B) thermoplastic resin powder as an active ingredient per 100 parts by weight of (A) unsaturated polyester resin
0 to 120 parts by weight, (C) liquid polymerizable monomer 30 to 12
A sheet molding compound made of an unsaturated polyester resin composition containing 0 parts by weight, (D) a curing agent and (E) a reinforcing material is laid inside the first mold, and then a sheet made of an elastic material is placed. The space formed by the sheet and the second molding die or pressure plate after being covered with the second molding die or pressure plate is 0.1 to 40 ° C. with a fluid of 0.1 to 100 ° C.
A method for molding an unsaturated polyester resin, which comprises pressurizing to 10 kgf / cm ² (gauge pressure). (5) The method for molding an unsaturated polyester resin according to any one of (1) to (4) above, wherein 2 to 15 sheet molding compounds having a thickness of 0.3 to 5 mm are laminated and laid.

[0026]

EXAMPLES The method for molding the unsaturated polyester resin of the present invention will be described with reference to examples, but the present invention is not limited thereto. Evaluation was performed by the following method. (1) Viscosity The viscosity was measured by storing two samples of the unsaturated polyester resin composition sampled at 40 ° C. for 24 hours and at 30 ° C. for 24 hours and 24 hours and 30 days thereafter. Before each viscosity measurement, they were placed in a constant temperature bath at 25 ° C., left for 1 hour, and then measured in an atmosphere of 25 ° C. and 60% relative humidity. The viscometer is a rotary viscometer Rheo Str manufactured by HAAKE.
Ess RS-100 type was used. (2) Releasability of release film SMC was cured at 40 ° C for 24 hours, then placed in an atmosphere of 25 ° C and relative humidity of 60% for 1 hour, and the release film was peeled by hand. did. ◯: Peeled off easily and no SMC component adhered to the release film side. Δ: Slightly difficult to peel off, but no SMC component adhered to the release film side. X: SMC component adheres to the release film side even if peeling is difficult or easy. (3) Average single particle size (when average single particle size is 10 μm or less) Using a sample obtained by adding 0.2 g of thermoplastic resin powder to 100 ml of water and ultrasonically dispersing A 000-fold observation photograph was taken, the length of 800 ± 100 single particles was measured, and the average length value on a number basis was determined.

Example 1 A mold releasing agent such as silicone wax was applied to the inner surface of a mold (FIG. 1) 1 for a boat-shaped container, and the composition 1 shown in Table 1 was applied thereon.
Consisting of a vertical 400 mm × width 500 mm × thickness 1 m
5 layers of SMC of m were laminated to form an uncured SMC layer 3. When the pressure plate 2 is covered, a silicone rubber pressure bag 4 with an air supply hose is installed in the space. Then 60
Air at 60 ° C. is fed into the bag 4 from the air supply hose 5 while heating the mold to 0 ° C. The bag 4 was expanded and brought into close contact with the SMC layer 3, and was pressed against the inner surface of the mold 1 with a uniform pressure of ² kgf / cm ² (gauge pressure). After 10 minutes, the pressure was released and the molded product was removed from the mold. As a result, a boat-shaped strong molded product having an outer surface faithful to the inner surface of the molding mold was obtained. Example 2 The present invention can perform the same molding using a pressure sheet 6 made of polyurethane as shown in FIG. 2 even in a mode in which pressurized air is sent from the air supply pipe 7 of the pressure plate 2. FIG. 2 shows the composition 2 of Table 1, vertical 400 mm × horizontal 5000 mm ×
Using SMC having a thickness of 1 mm, three layers were laminated on the inner surface of the molding die 1, and a polyurethane release film 8 was placed on the polyurethane sheet 6, and then the die was heated to 50 ° C.
While heating to 50 ° C., air of 1 kgf / cm ² (gauge pressure) at 50 ° C. was sent from the air supply pipe. 1kgf / cm on the inner surface of the mold while the polyurethane sheet expands and adheres to the SMC layer
Pressed with a pressure of ² (gauge pressure). The obtained molded product was a boat-shaped strong container having an outer surface faithful to the inner surface of the mold.

[0028]

[Table 1]

[Note] 1) Unsaturated polyester resin 1: propylene glycol / neopentyl glycol / isophthalic acid / fumaric acid =
15/35/20/30 mol% random copolymer, number average molecular weight 3,300. 2) Unsaturated polyester resin 2: propylene glycol / ethylene glycol / phthalic anhydride / fumaric acid = 30
/ 20/20/30/20 mol% random copolymer, number average molecular weight 2,100. 3) ZEON F-320: polymethylmethacrylate resin powder, average single particle size 1.9 μm, weight average degree of polymerization 30,
000, manufactured by Nippon Zeon Co., Ltd. 4) Percure O: curing agent, t-butylperoxy-2
-Ethyl hexanoate, half-life of 65 ° C x 24 hours, manufactured by NOF CORPORATION. 5) Perkadox 16: curing agent, bis-4-t-butylcyclohexyl peroxydicarbonate, half-life 4
0 ° C x 10 hours, manufactured by Kayaku Akzo Co., Ltd. 6) Stearic acid: a release agent, manufactured by Sakai Chemical Industry Co., Ltd. 7) NS-100: Filler, calcium carbonate, manufactured by Nitto Koka Kogyo Co., Ltd.

[0030]

EFFECTS OF THE INVENTION According to the present invention, an unsaturated polyester resin composition which can be converted into SMC in a short time, has good storage stability, and has a good release film release property is used, and a low-temperature low-pressure pressurization by SMC is used. The bag method enables simple molding.

[0031]

[Brief description of drawings]

FIG. 1 is a sectional view of a molding machine showing a method for molding an unsaturated polyester resin according to an embodiment of the present invention.

FIG. 2 is a sectional view of a molding machine showing a method for molding an unsaturated polyester resin according to another embodiment of the present invention.

[Explanation of reference numerals] 1 first mold 2 pressure plate 3 SMC layer 4 bag made of elastic material 5 air supply hose 6 sheet made of elastic material 7 air supply pipe 8 release film

Claims (2)

[Claims] 1. (A) Unsaturated polyester resin, (B)
A sheet molding compound comprising an unsaturated polyester resin composition containing a thickener containing a thermoplastic resin powder as an active ingredient, (C) a liquid polymerizable monomer, (D) a curing agent and (E) a reinforcing material. Laying inside the one mold,
Next, a bag made of an elastic material is placed, covered with a second mold or a pressure plate, and then the bag is pressurized with a fluid of 40 to 100 ° C. to 0.1 to 10 kgf / cm ² (gauge pressure). Method for forming unsaturated polyester resin. 2. (A) unsaturated polyester resin, (B)
A sheet molding compound comprising an unsaturated polyester resin composition containing a thickener containing a thermoplastic resin powder as an active ingredient, (C) a liquid polymerizable monomer, (D) a curing agent and (E) a reinforcing material. Laying inside the one mold,
Next, a sheet made of an elastic material is placed, covered with a second molding die or pressure plate, and then a space formed by the sheet and the second molding die or pressure plate is filled with a fluid of 40 to 100 ° C.
A method for molding an unsaturated polyester resin, which comprises pressurizing to 1 to 10 kgf / cm ² (gauge pressure).