JPH10309755A - Manufacture of fiber-reinforced plastic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve glossiness, smoothness of an SMC molding having a design pattern by placing a prepreg sheet so that its surface side is brought into contact with a surface of a mold, superposing sheet molding compound having a specific molding shrinkage factor thereon, and heating and pressurizing it. SOLUTION: A prepreg sheet is placed so that a surface side of the sheet is brought into contact with a mold for forming a surface of an SMC molding. Sheet molding compound having a molding shrinkage factor of -0.05 to +0.03 is superposed thereon, heated and pressurized. The SMC contains unsaturated polyester resin, polymerizable monomer and saturated polyester resin as indispensable components. In this case, when a mixing amount of the unsaturated resin is a pts.wt., the a, b and c are selected so that a mixing amount of the monomer is b pts.wt., and a mixing amount of the saturated resin is c pts.wt., the relation of 0.4<=b/(a+c)<=1.1 is satisfied and the relation of 0.3<=c/a<=0.6 is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a fiber-reinforced plastic molded product.

[0002]

2. Description of the Related Art Various fiber-reinforced composite materials are widely used in various fields such as aerospace, land transportation, ships, construction civil engineering, industrial parts, audio equipment, agricultural and fishing materials, and sporting goods. A method for producing a fiber-reinforced plastic molded article (hereinafter, referred to as an SMC molded article) using a sheet molding compound (hereinafter, referred to as an SMC) has attracted attention because a molded article can be produced and the productivity is high.

[0003] SMC is usually added to an unsaturated polyester resin with a low shrinkage agent, a thickener, a filler as a secondary material,
An unsaturated polyester resin composition mixed with a release material, a curing catalyst, a curing retarder, a colorant, and the like is applied on a plastic film, and then is impregnated into reinforcing fibers to form a sheet, which is then rolled. And aged at room temperature or under heating.

[0004] An SMC molded product is manufactured by loading one or two or more SMCs into a mold according to the thickness thereof and subjecting them to high-temperature press molding into a predetermined shape by a press molding method. As a method of manufacturing an SMC molded product having a picture pattern, a method of integrally forming a SMC by heating and pressurizing using a prepreg sheet using a woven fabric or a nonwoven fabric on which a pattern or the like is printed in advance, and manufacturing a bathtub (particularly, Kaisho 50-9665
No. 6), a sheet in which a transparent synthetic resin is impregnated with a cloth provided with at least one of a pattern, a pattern, and a color is integrally formed with the SMC to produce a bathtub with a pattern on the flange surface or inner surface. Method (JP-A-53-14676)
No. 9), when a glass fiber sheet having a pattern that can be impregnated with a resin and a molding material are pressurized and heated by a mold, the molten resin in the molding material passes through the glass fiber sheet with the pattern, and Method for producing a reinforced plastic molded article characterized by forming a transparent layer
JP-A-33571), a method of hot-press forming a prepreg sheet impregnated with a thermosetting resin into a pattern-impregnated sheet and an SMC using a strand mat to produce a panel with a picture pattern. Kaisho 62-152733
For example, are known.

[0005]

However, in these conventional manufacturing methods, a high cycle of manufacturing, protection of a picture and a pattern, and improvement of abrasion resistance of a surface can be achieved. However, the obtained SMC molded product is smooth. However, there is a problem that poor design and gloss cannot be obtained because of poor appearance and gloss.

It is an object of the present invention to provide a method for producing an SMC molded article having good gloss and smoothness without warpage or distortion using SMC. Also,
An object of the present invention is to provide a method of manufacturing an SMC molded product having a picture pattern in addition to the object of the present invention. A third object of the present invention is to provide an SMC suitable for such a manufacturing method.

[0007]

Means for Solving the Problems In the present invention, claim 1 is provided.
In the invention described in the above, the prepreg sheet is placed so that the surface side of the prepreg sheet is in contact with the mold surface forming the surface of the SMC molded product, and the molding shrinkage is -0.05 to
This is a method for producing an SMC molded product, characterized in that a sheet molding compound of + 0.03% is overlaid and heated and pressed.

[0008] Here, the molding shrinkage is a percentage of the difference between the dimension of the mold and the dimension of the SMC molded product when the SMC is molded using a mold and then cooled to 23 ° C. ,
It can be obtained by the mathematical formula shown in Expression 2.

[0009]

S = (L ₀ −L) × 100 / L ₀ where S: molding shrinkage, L ₀ : mold size at 23 ° C., L: SMC molded product size at 23 ° C.

When the molding shrinkage is less than -0.05%,
Demolding after molding becomes difficult, workability decreases, and
If it exceeds + 0.03%, the smoothness of the surface of the SMC molded product,
The gloss cannot be obtained, and the SMC molded product warps or warps. From this, the molding shrinkage rate was -0.03
More preferably, it is 0.02%.

Next, a second aspect of the present invention is to provide a prepreg sheet comprising a thermosetting resin composition which becomes a transparent cured product and a fibrous base material, and having a transparent pattern. This is a method for producing an SMC molded product using a prepreg sheet obtained by impregnating a conductive resin and having a pattern.

Further, the invention according to claim 3 is a method for manufacturing an SMC molded product according to claim 1 or 2,
As the MC, the unsaturated polyester resin, the polymerizable monomer and the saturated polyester resin are essential components, the compounding amount of the unsaturated polyester resin is a part by weight, the compounding amount of the polymerizable monomer is b part by weight, the saturated polyester resin Is a resin composition for SMC, wherein an unsaturated polyester resin, a polymerizable monomer, and a saturated polyester resin are compounded in a range satisfying the formulas (1) and (2) when the compounding amount is c parts by weight. This is a method for producing an SMC molded product using an SMC using a product.

## EQU3 ## 0.4 ≦ b / (a + c) ≦ 1.1 (1) 0.3 ≦ c / a ≦ 0.6 (2)

If the values of a, b and c deviate from this range, excellent surface smoothness of the SMC molded product cannot be obtained. From this, it is more preferable to mix the unsaturated polyester resin, the polymerizable monomer, and the saturated polyester resin in a range that satisfies Formulas (3) and (4).

0.45 ≦ b / (a + c) ≦ 0.75 (3) 0.35 ≦ c / a ≦ 0.5 (4)

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The prepreg sheet used in the present invention is composed of a thermosetting resin composition which becomes a transparent cured product and a fiber base material, and which is brought into an appropriate cured state at room temperature or by heating. Is used. The prepreg sheet is, for example, a fiber substrate and a thermosetting resin composition to be a transparent cured product placed between two plastic films, and a roll is pressed from above the plastic film to form a transparent cured product. It can be produced by impregnating a curable resin composition into a fiber base material and heating it to an appropriate cured state at room temperature or by heating. More specifically, the fiber substrate and the thermosetting resin composition to be a transparent cured product in this order, or the reverse order thereof, or, the thermosetting resin composition to be a transparent cured product, the fiber substrate and A thermosetting resin composition to be a transparent cured product is placed on one plastic film in this order, another plastic film is stacked thereon, and a roll is pressed from above on the transparent cured product. The fibrous base material is impregnated with the thermosetting resin composition as described below, and is made into an appropriate cured state at room temperature or by heating to obtain a prepreg sheet.

[0015] A nonwoven fabric is preferred as the fiber base material. Specifically, those made of organic fibers such as polyester, nylon, acryl, and cellulose derivatives can be used. Preferably has a weight of 10~120g / m ² per unit area, it is more preferable at 20 to 80 g / m ^2. If the weight per unit area is less than 10 / m ^{2, if} it is smaller, the prepreg sheet tends to be torn during molding and the appearance tends to be poor. If the weight per unit area exceeds 120 g / m ² , the adhesiveness between the prepreg sheet and the SMC tends to be poor. As the fiber base material, a woven fabric, a nonwoven fabric, a felt, a mat, or the like made of glass fiber can be used in addition to the above-described materials.

The plastic film used for producing the prepreg sheet is not particularly limited as long as it has heat resistance and releasability and is insoluble in the thermosetting resin impregnating the fiber base material. And a plastic film such as a polyamide resin, a polyester resin, and a fluororesin.

A prepreg sheet having a pattern can be obtained by using a fiber substrate with a pattern which has been printed in advance. The printing method of the picture pattern on the fiber base material may be any one of letterpress printing, intaglio (gravure) printing, offset printing, silk printing and the like. The ink used for printing a pattern is preferably a mixture of an unsaturated polyester resin, an acrylic resin, a nitrocellulose-based resin, or the like, and a pigment or dye. Commercially available products of such inks include, for example, NL-ALFA
(The Inktec Co., Ltd., trade name), SAM, BC heat resistance, NC, Chemical X (all above, manufactured by Showa Ink Industries, Ltd.
(Product name).

The pattern can also be obtained by transferring the pattern from a releasable support sheet or film on which a transfer layer containing the pattern is formed. For example, a peelable support sheet or film on which a transfer layer is formed is used on one side of a plastic film used when manufacturing a prepreg sheet, and the surface on which the transfer layer is formed faces upward, and a fiber base is placed thereon. Laminate the materials, further place the thermosetting resin composition to be a transparent cured product, cover it with another plastic film, and apply a roll pressure from above on the transparent cured product. The thermosetting resin composition to be impregnated into the fiber base material, and after being brought to an appropriate cured state at room temperature or by heating, peeling the release support sheet or film, the transfer layer and the transparent cured product And transferred to the resin surface of the thermosetting resin composition.

The releasable support sheet or film on which the transfer layer including the picture pattern is formed is particularly suitable as long as it has heat resistance and releasability and is insoluble in the thermosetting resin impregnating the fiber base material. There is no limitation, the above-mentioned plastic film, a metal foil such as an aluminum foil, a metal foil bonded to another film, and a resin having a releasable property on the surface of paper or a plastic film. It may be applied. As the patterning ink for forming the transfer layer including the pattern on the peelable support sheet or film, the same ink as that used for printing the pattern on the fiber base material can be used.

Regardless of the method of forming the picture pattern, the picture pattern may be any pattern such as a wood pattern, a stone pattern, a natural pattern such as a cloth pattern, a geometric pattern, a character, or a symbol. Good.

As the thermosetting resin constituting the thermosetting resin composition to be a transparent cured product, an unsaturated polyester resin or a vinyl ester resin is preferable because transparency is required for the cured product. An unsaturated polyester resin or a vinyl ester resin is dissolved in a polymerizable monomer, and a curing agent or the like is blended to obtain a thermosetting resin composition that becomes a transparent cured product.

The unsaturated polyester resin used here is obtained by polycondensation of an unsaturated polybasic acid and a polyhydric alcohol. If necessary, a polybasic acid other than the unsaturated polybasic acid, for example, a saturated polybasic acid is used in combination.

As the unsaturated polybasic acid, generally, unsaturated dibasic acids such as maleic acid, fumaric acid, itaconic acid,
Citraconic acid, chlormaleic acid and the like are used. Among them, maleic acid or fumaric acid, which is commonly used for producing unsaturated polyester resin, is preferably used as an essential component. These can use the acid anhydride.
The unsaturated dibasic acid is usually added in an amount of 0.1 to 1 mol of the polybasic acid component used in the production of the unsaturated polyester resin.
It is preferably used in the range of 3 to 1.0 mol. Examples of polybasic acids other than unsaturated polybasic acids include isophthalic acid, phthalic acid, phthalic anhydride, terephthalic acid, nitrophthalic acid, tetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, halogenated phthalic anhydride, oxalic acid, Malonic acid, succinic acid, adipic acid, sebacic acid and the like can be mentioned, and these acid anhydrides may be used. Polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, hydrogenated bisphenol A, an alkylene oxide adduct of bisphenol A, and the like.

The unsaturated polyester resin has a weight average molecular weight (hereinafter referred to as "weight average molecular weight") determined by gel permeation chromatography in terms of standard polystyrene within the range of 8,000 to 50,000, preferably 10, 50,000.
It is appropriately selected from the range of 000 to 45,000. Further, the acid value is appropriately selected from the range of 5 to 40 KOH mg / g, preferably from the range of 10 to 25 KOH mg / g. These ranges are within the range of the weight average molecular weight and the acid value of the commonly used unsaturated polyester resin.

The vinyl ester resin is obtained by reacting an epoxy resin with an unsaturated monobasic acid. Commercial products can be used as the epoxy resin. Commercial products used include, for example, Epicoat 828, 1001, 15
2, 154 (all trade names of Shell Chemical Co., Ltd.), Araldite AER280, 6071 (all trade names of Asahi Ciba Co., Ltd.), Epiclon 850, 860, 1050 (all trade names of Dainippon Ink and Chemicals, Inc.), EPOMIC R-1
40, 301 (trade name of Mitsui Petrochemical Co., Ltd.), D
EN-431, 438, 439 (both trade names of Dow Chemical Company) and the like. Acrylic acid and methacrylic acid are typical examples of the unsaturated monobasic acid, and acrylic acid esters and methacrylic acid esters are also included. The unsaturated monobasic acid has a carboxyl group of the unsaturated monobasic acid of 0.9 to 1 per mole of the epoxy group of the epoxy resin.
The reaction is performed in a range of 2 mol. This range is a condition usually employed in the production of vinyl ester resin.

The vinyl ester resin has a weight average molecular weight in the range of 500 to 5,000, preferably 800 to 5,000.
It is appropriately selected within the range of 4,000. The acid value is in the range of 0.1 to 40 KOHmg / g, preferably 5
It is appropriately selected within the range of ２０20 KOH mg / g. These ranges are within the range of the weight average molecular weight and the acid value of a commonly used vinyl ester resin.

Examples of the polymerizable monomer include aromatic vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, dichlorostyrene, divinylbenzene, t-butylstyrene, methyl methacrylate, and methacrylic. Ethyl acrylate, alkyl methacrylates such as butyl methacrylate, alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, neopentyl glycol dimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, dimethacrylate Methacrylic acid esters of polyhydric alcohols such as pentaerythritol hexamethacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol pen Acrylate, polyvalent methacrylic acid esters of alcohols such as dipentaerythritol hexaacrylate, diallyl phthalate, triallyl cyanurate, and acrylonitrile.

The cured state of the prepreg sheet can be adjusted by appropriately selecting a curing agent (in some cases, combining two or more curing agents), the amount of the curing agent, the curing conditions, and the like. Specific examples of the curing agent include organic peroxides such as methyl ethyl peroxide, acetylacetone peroxide, lauroyl peroxide, methyl isobutyl ketone peroxide, t-butyl perbenzoate, and dicumyl peroxide. The compounding amount of the curing agent is preferably 0.5 to 3 parts by weight based on 100 parts by weight of the total amount of the thermosetting resin and the polymerizable monomer. If the amount of the curing agent is less than 0.5 parts by weight, curing tends to be insufficient. Also, the amount of the curing agent is 3
Even if the amount exceeds the weight part, the effect does not change and the cost increases.

Here, the moderately cured state means that the prepreg sheet can maintain its shape, is not sticky, and has a reactive group (crosslinking point) sufficient to enable adhesion to the SMC at the time of complete curing. It is a state. Further, it is preferable that the material has strength and flexibility that can follow the uneven shape and joints of the mold during molding and does not cause outflow, crack breakage, sheet tear, and the like. For this reason, the degree of cure of the prepreg sheet is preferably set to 50 to 95%, and particularly preferably set to 70 to 90%. Although there is no particular limitation on the curing method, it is generally carried out in a drying oven at 40 to 80 [deg.] C. when heating and curing.

The degree of cure is determined as follows. Several sheets of a thermosetting resin composition used for manufacturing a prepreg sheet applied to a glass plate to a thickness of about 200 μm are prepared, covered with a plastic film, and the time is changed at a predetermined temperature (for example, 10 minutes). , 20 minutes, 30 minutes)
Heat. For the thermosetting resin composition before heating and the thermosetting resin composition after heating, respectively, a differential scanning calorimeter (for example, Du Pont 9900 Therm)
al Analyzer (Du Pont Co.,
)) Is used to measure the reaction heat capacity. Assuming that the reaction heat capacity of the thermosetting resin composition before heating is A and the reaction heat capacity of the thermosetting resin composition after heating is B, the reaction rate α is determined according to Equation 5.

Α (%) = (A−B) × 100 / A

The obtained reaction rate α is plotted against the heating time to prepare a calibration curve of the reaction rate with respect to the heating time. The degree of cure of the prepreg sheet is determined from the heating time at a predetermined temperature by using the above calibration curve to determine a reaction rate corresponding to the heating time, and this is defined as the degree of curing.

In the production of the prepreg sheet, it is preferable that the weight of the thermosetting resin composition to be a transparent cured product is in the range of 100 to 1,000 g / m ² . If it is less than 100 g / m ² , the gloss of the surface is deteriorated, and the adhesion to SMC tends to be deteriorated. On the other hand, if it exceeds 1,000 g / m ² , the occurrence of cracks during molding tends to increase. From this, the weight per unit area is 300 to 620 g / m ^2.
It is more preferable to be within the range. The thickness of the prepreg sheet is preferably in the range of 100 to 800 μm, excluding the plastic film, the release support sheet or the film, and more preferably 200 to 500 μm.
Is more preferable. If the prepreg sheet is too thin, the surface lacks gloss and the desired design cannot be obtained. If the prepreg sheet is too thick, cracks increase during molding and the appearance is reduced.

As the unsaturated polyester resin used for the SMC, the same unsaturated polyester resin as that used for producing the prepreg sheet can be used. However, regarding the weight average molecular weight, 5,000 to 20,
000, preferably 7,000 to 1
More preferably, it is within the range of 5,000. Also,
The acid value is preferably in the range of 10 to 40 KOH mg / g, and more preferably in the range of 15 to 35 KOH mg / g. Weight average molecular weight of 5,0
If it is less than 00, the strength of the molded article tends to decrease, and if it exceeds 20,000, the viscosity of the resin increases and the S
There is a tendency that workability during the fabrication of MC is impaired. Acid value is 10K
If it is less than OH mg / g, the SMC tends to be sticky and the workability is deteriorated. If it exceeds 40 KOH mg / g, the molded article tends to be difficult to separate from the mold.

As the polymerizable monomer used for the SMC, the same polymerizable monomer as that used for producing the prepreg sheet can be used. However, from the viewpoints of cost, workability, and the like, it is preferable that at least 70% by weight of the total amount of the polymerizable monomer components be styrene.

The saturated polyester resin used for the SMC is obtained by reacting a saturated polybasic acid with a polyhydric alcohol. As the saturated polybasic acid, a polybasic acid used in combination with the unsaturated polybasic acid in the synthesis of the unsaturated polyester resin can be used. Saturated polyester resins act as low shrinkage agents.

The weight average molecular weight of the saturated polyester resin used here is preferably in the range of 7,000 to 30,000. 10,000-25,000
More preferably, it is within the range of 0. If the weight average molecular weight is less than 7,000, the effect of properly shrinking the SMC molded product becomes insufficient, and the surface smoothness tends to deteriorate. On the other hand, if the weight average molecular weight exceeds 30,000, the viscosity is too high, and the impregnation property becomes poor when producing SMC. From this, saturated polyester resin,
More preferably, the weight average molecular weight is in the range of 10,000 to 25,000.

In producing the SMC, a filler is usually used in addition to the unsaturated polyester resin, the polymerizable monomer and the saturated polyester resin. Examples of the filler include calcium carbonate, aluminum hydroxide, clay, alumina powder, talc, silica powder, glass powder, and the like, and it is preferable to use calcium carbonate from the viewpoints of cost and large filling property. The filler is preferably blended in the range of 100 to 300 parts by weight based on 100 parts by weight of the total of a, b and c. When the amount is less than 100 parts by weight, the low shrinkage effect is small and sufficient surface smoothness is hardly obtained. On the other hand, if it exceeds 300 parts by weight, the viscosity of the resin composition for SMC is too high, so that the impregnating property becomes inferior when producing SMC, and the mechanical properties of the obtained SMC molded product tend to decrease. . From this, the compounding amount of the filler, with respect to 100 parts by weight of the total amount of the unsaturated polyester resin, the polymerizable monomer and the saturated polyester resin,
More preferably, it is blended in the range of 150 to 250 parts by weight.

A curing catalyst is blended in the SMC. Examples of the curing catalyst to be blended include t-butyl peroxybenzoate, t-hexylperoxybenzoate, benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl peroctate, and 2,5-dimethyl-.
Organic peroxides such as 2,5-di- (t-butylperoxy) hexane and 2,5-dimethylhexyl-2,5-di (peroxybenzoate) are included. In order to obtain good surface smoothness in a normal molding time, it is preferable to use t-butylperoxybenzoate or t-hexylperoxybenzoate alone or in combination with another curing catalyst. The amount of the curing catalyst used is the total amount of the above-mentioned a, b and c which is usually used in SMC.
It is appropriately selected from the range of 0.5 to 3 parts by weight with respect to 0 parts by weight.

In addition to the curing agent, another low-shrinkage agent may be further added, if necessary. As the low shrinkage agent, conventional S
A thermoplastic resin material generally used in MC can be used as it is. Specifically, polybutadiene, styrene-butadiene copolymer, polystyrene, polyisoprene, rubbery polymers such as polychloroprene,
Polystyrene, polyvinyl acetate, polycaprolactam,
Examples include polymethacrylic acid and polymethyl methacrylate. Styrene-butadiene copolymer is most preferred from the viewpoint of the effect on the effects of the present invention and easy availability and low cost.
Commercial products include Kariflex TR-KX410S and DX-1300 (Shell Co., trade name), ZFT-13
00 and ZFT-5000 (Nippon Zeon Co., Ltd., trade name) and the like, having a weight average molecular weight of 50,000 to
It is preferably in the range of 500,000 and 10
More preferably, it is in the range of from 000 to 300,000. If the weight average molecular weight is smaller than the above range, S
If the mechanical properties and the low shrinkage effect of the MC molded product are not sufficiently obtained, and if the weight average molecular weight is larger than the above range, the viscosity becomes too high and the impregnation becomes poor.

In addition, a thickener, a curing retarder, a release agent,
A coloring agent, a reinforcing material, and the like may be added. Examples of the thickener include divalent metal oxides and divalent metal hydroxides, for example, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and the like. These are used alone or in combination. The amount of the thickener used is 7 parts with respect to 100 parts by weight of the total of a, b and c.
It is preferably not more than 0.1 parts by weight.
It is preferable to use at least part by weight. If the amount of the thickener is less than 0.1 part by weight, sufficient thickening tends not to be performed, and if it exceeds 7 parts by weight, the hot water resistance of the molded article tends to deteriorate.

The curing retarder includes, for example, hydroquinone, p-benzoquinone, methylhydroquinone and the like, preferably 0.1 parts by weight or less based on 100 parts by weight of the total of a, b and c. When used, it is preferable to use 0.001 part by weight or more.

As a release agent, zinc stearate is generally used, and its use amount is preferably 5 parts by weight or less based on 100 parts by weight of the total of a, b and c. It is preferable to use 0.5 parts by weight or more.

As the colorant, a pigment such as carbon black can be used. The amount of the pigment is preferably 5 parts by weight or less based on 100 parts by weight of the total of a, b and c. In this case, it is preferable to use 0.1 parts by weight or more.

A curing agent or the like is blended with the unsaturated polyester resin,
An SMC is prepared by impregnating a fiber reinforcing material such as a reinforcing fiber mat, a cut reinforcing fiber laminate, or the like with a short cut length before a thickening progresses as a composition for MC. As the fiber of the fiber reinforcement, glass fiber is the most common, but chopped strand mats and rovings of fibers such as polyester fiber, acrylic fiber, polyvinyl alcohol fiber, carbon fiber and polyamide fiber can also be used. The amount of the fiber reinforcing material to be used is appropriately selected within the range of 10 to 50 parts by weight, which is commonly used, based on 100 parts by weight of the total amount of the composition for SMC.

In the production of the SMC molded product, the area ratio covered by the SMC on which the molding surface of the lower die is placed, that is, the charge rate is preferably in the range of 50 to 100%.
More preferably, it is in the range of 60 to 100%. When the charge rate is less than 50%, the prepreg sheet tends to be torn during molding, and the appearance tends to be reduced. The molding temperature is in the range of 100 to 180 ° C, and more preferably in the range of 110 to 160 ° C. The molding pressure is in the range of 5 to 12 MPa,
A more preferred condition is within the range of 8 to 10 MPa. The molding time is about 1 to 10 minutes. These ranges of molding temperature, molding pressure and molding time are conditions commonly used in the production of SMC molded products, and the production can be carried out by appropriately selecting from these ranges.
Under these conditions, a good SMC
Molded articles can be manufactured.

[0046]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Preparation of unsaturated polyester resin composition (A) for prepreg sheet: 327 g (0.45 mol) of isophthalic acid, 9 g (0.027 mol) of propylene glycol, 292 g (0.62 mol) of neopentyl glycol and hydroquinone 0 .
05 g was charged into a 1,000 ml four-necked flask equipped with a thermometer, a stirring blade, an inert gas inlet tube, and a condenser, heated to 225 ° C. under a nitrogen stream, and subjected to a dehydration condensation reaction by a conventional method. The reaction was stopped when the acid value reached 10 KOHmg / g.

236 g of maleic anhydride (0.5 g)
5 mol), 122 g of propylene glycol (0.367)
Mol) and 13 g of neopentyl glycol (0.027
Mol), and the temperature was raised again to 225 ° C. to cause a dehydration condensation reaction. When the acid value reached 24 KOH mg / g, the reaction temperature was lowered to 215 ° C., and the reaction was continued.
When the acid value reached 20 KOH mg / g, the reaction was stopped to obtain an unsaturated polyester resin. To this was added 0.1 g of hydroquinone, and the weight average molecular weight was determined to be 40,300. 60 parts by weight of the obtained unsaturated polyester resin was dissolved in 40 parts by weight of styrene monomer, and 1.0 part by weight of bis- (4-t-butylcyclohexyl) peroxydicarbonate was added as a curing agent, and the prepreg sheet was added. An unsaturated polyester resin composition (A) for use was prepared.

Preparation of unsaturated polyester resin composition (B) for SMC 1586 g (1.00 mol) of maleic anhydride, 1414 g (1.15 mol) of propylene glycol and 0.3 g of hydroquinone were added to a thermometer, stirring blade, The mixture was charged into a 3,000 ml four-necked flask equipped with an active gas inlet tube and a condenser, heated to 210 ° C. under a nitrogen stream, allowed to undergo a dehydration condensation reaction by a conventional method, and had an acid value of 21 KOHmg.
/ G, the reaction was stopped to obtain an unsaturated polyester resin. To this was added 0.15 g of hydroquinone, and the weight average molecular weight was determined in the same manner.
It was 8,700. 70 parts by weight of the obtained unsaturated polyester resin was dissolved in 30 parts by weight of styrene monomer to obtain SM.
An unsaturated polyester resin composition for C (B) was prepared.

Preparation of saturated polyester resin composition (C) for SMC 656 g (1.00 mol) of adipic acid, 182 g (0.65 mol) of ethylene glycol, 162 g (0.40 mol) of 1,4-butanediol and hydroquinone 0.1
g was charged into a 1,000 ml four-necked flask equipped with a thermometer, a stirring blade, an inert gas inlet tube, and a condenser. The temperature was raised to 215 ° C. under a nitrogen stream, and a dehydration condensation reaction was carried out by a conventional method. Then, when the acid value reached 24 KOHmg / g, the pressure was reduced to 426.6 hPa, and the reaction was continued as it was. When the acid value reached 5.0 KOHmg / g, the reaction was stopped to obtain a saturated polyester resin. To this was added 0.1 g of hydroquinone, and the weight average molecular weight was determined in the same manner. The result was 27,700. 60 parts by weight of the obtained saturated polyester resin was dissolved in 40 parts by weight of styrene monomer to prepare a saturated polyester resin composition for SMC (C).

Preparation of Prepreg Sheet (A-1) Using a polyurethane-based ink NL-ALFA (manufactured by The Inktec Co., Ltd.), a thickness obtained by printing a marble-like grain pattern on one side by a gravure printing method. A 50 μm polyester film was cut into a size of 22 cm × 22 cm. 15 g of the unsaturated polyester resin composition for prepreg sheet (A) immediately after preparation is placed on the surface with the pattern printed thereon, and the top is covered with a 50 μm-thick polyester film, and pressed with a roller. The unsaturated polyester resin composition (A) for a prepreg sheet was uniformly stretched and defoamed. This was cured in a curing furnace maintained at 70 ° C. for 30 minutes, taken out, and the polyester film on which the pattern was printed was peeled off. The marble-like pattern was transferred to the resin layer. 22cm x 22c on the surface from which the polyester film with the pattern was printed
The polyester resin non-woven fabric (weight per unit area is 15 g / m ² ) cut into a size of m is overlapped, and 25 g of the unsaturated polyester resin composition (A) for a prepreg sheet is further placed on the non-woven fabric. It was covered with a polyester film having a thickness of 50 μm, and similarly pressed with a roller to uniformly push and stretch the unsaturated polyester resin composition (A) for a prepreg sheet, and simultaneously impregnated in a polyester resin nonwoven fabric. This was cured at 70 ° C. for 20 minutes and taken out. At this time, the degree of cure of the unsaturated polyester resin composition for prepreg sheets (A) was 90%. Next, both polyester films were peeled off, and the thickness was measured. The thickness was 480 μm, and there was no stickiness and the handleability was excellent. The prepreg sheet obtained by the above method was cut into a size of 22 cm × 22 cm to prepare a prepreg sheet (A-1).

Preparation of Prepreg Sheet (A-2) On a 50 μm-thick polyester film, 15 g of the unsaturated polyester resin composition for prepreg sheet (A) immediately after preparation was placed, and the above prepreg sheet (A-
A marble-like pattern is printed on one side with the same ink as in 1), a polyester nonwoven fabric having a size of 22 cm × 22 cm is overlaid with the pattern side up, and the unsaturated polyester resin composition for prepreg sheet ( A) was placed in an amount of 15 g and covered with a polyester film having a thickness of 50 μm.
From above, the mixture was pressed with a roller to uniformly stretch and defoam the unsaturated polyester resin composition for prepreg sheets (A), and at the same time impregnated in a polyester nonwoven fabric. Next, the mixture was cured in a curing furnace maintained at 70 ° C. for 12 minutes and taken out to obtain a prepreg sheet. At this time, the degree of cure of the unsaturated polyester resin composition for prepreg sheets (A) was 70%. Next, when the two polyester films were peeled off and the thickness was measured, the thickness was 310 μm, and there was no stickiness and the handleability was excellent. The prepreg sheet obtained by the above method was cut into a size of 22 cm × 22 cm to prepare a prepreg sheet (A-2).

Example 1 Unsaturated polyester resin composition for SMC (B) 63.0
Parts by weight, SMC saturated polyester resin composition (C) 2
6.0 parts by weight, 200 parts by weight of calcium carbonate, 1.5 parts by weight of t-butyl peroxybenzoate as a curing agent,
A resin composition for SMC was prepared by mixing 3.0 parts by weight of zinc stearate and 1.2 parts by weight of magnesium oxide as a thickener. The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. Is b parts by weight and the amount of the saturated polyester resin is c parts by weight, b /
(A + c) = 0.68 and c / a = 0.35. Two pieces of a polyethylene film having the SMC resin composition applied to the surface thereof were prepared, and the two sides of the SMC resin composition applied were faced to each other, and a glass roving cut to a length of 1 inch was sandwiched therebetween. . This was aged at 40 ° C. to produce SMC. The glass roving was adjusted to 25% by weight in the SMC.
The aging conditions are as follows: only the resin composition for SMC is 40 ° C.
And a viscosity of 20,000 Pa · s when measured at 40 ° C. with a Brookfield HBT viscometer.
Conditions.

The surface is flat and its size is 22 cm × 22
cm using a male die (upper die)
A female mold (lower mold) is charged with 550 g of SMC at a charge rate (meaning a ratio of the molded surface of the upper mold covered by the placed SMC) to 80.
%, Tighten the male mold, and the male mold temperature is 14
The plate was heated and pressurized for 5 minutes under the conditions of 5 ° C., a female mold temperature of 140 ° C., and a pressure of 8 MPa to produce a flat molded article of 22 cm × 22 cm × 0.5 cmt. Also, using the same press equipment,
The prepreg sheet (A-1) is stacked on the SMC, and the male mold is tightened. The male mold temperature is 145 ° C, and the female mold temperature is 140.
At 5 ° C. and a pressure of 8 MPa for 22 minutes.
A patterned flat molded product of cm × 22 cm × 0.5 cmt was produced.

Example 2 Using the prepreg sheet (A-2), a patterned flat molded product was produced in the same manner as in Example 1.

Example 3 Unsaturated polyester resin composition for SMC (B) 57.0
Parts by weight, saturated polyester resin composition for SMC (C) 3
2.0 parts by weight, 210 parts by weight of calcium carbonate, 1.5 parts by weight of a curing agent, 3.0 parts by weight of zinc stearate, and 1.2 parts by weight of a thickener were mixed to prepare a resin composition for SMC.
The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. Is b parts by weight and the amount of the saturated polyester resin is c parts by weight, b / (a + c)
= 0.69 and c / a = 0.48. Thereafter, in the same manner as in Example 1, a flat molded product and a flat molded product with a pattern were produced.

Example 4 Using the prepreg sheet (A-2), a patterned flat molded product was produced in the same manner as in Example 3.

Comparative Example 1 Unsaturated polyester resin composition for SMC (B) 58.0
Parts by weight, saturated polyester resin composition for SMC (C) 4
2.0 parts by weight, 200 parts by weight of calcium carbonate, 1.5 parts by weight of a curing agent, 3.0 parts by weight of zinc stearate, and 1.2 parts by weight of a thickener were mixed to obtain a resin composition for SMC.
The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. Is b parts by weight and the amount of the saturated polyester resin is c parts by weight, b / (a + c)
= 0.52, c / a = 0.62. Thereafter, in the same manner as in Example 1, a flat molded product and a flat molded product with a pattern were produced.

Comparative Example 2 Unsaturated polyester resin composition for SMC (B) 92.0
Parts by weight, saturated polyester resin composition for SMC (C)
8.0 parts by weight, 200 parts by weight of calcium carbonate, 1.5 parts by weight of a curing agent, 3.0 parts by weight of zinc stearate, and 1.2 parts by weight of a thickener were mixed to prepare a resin composition for SMC.
The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. Is b parts by weight and the amount of the saturated polyester resin is c parts by weight, b / (a + c)
= 0.45 and c / a = 0.08. Thereafter, in the same manner as in Example 1, a flat molded product and a flat molded product with a pattern were produced.

Comparative Example 3 Unsaturated polyester resin composition for SMC (B) 57.0
Parts by weight, saturated polyester resin composition for SMC (C) 1
7.0 parts by weight, styrene monomer 26.0 parts by weight, calcium carbonate 200 parts by weight, hardener 1.5 parts by weight, zinc stearate 3.0 parts by weight, thickener 1.2 parts by weight, This was a resin composition for SMC. The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. Is b parts by weight and the amount of the saturated polyester resin is c parts by weight, b / (a + c) = 1.00, c / a =
0.26. Thereafter, in the same manner as in Example 1, a flat molded product and a flat molded product with a pattern were produced.

Comparative Example 4 Unsaturated polyester resin composition for SMC (B) 50.0
Parts by weight, saturated polyester resin composition for SMC (C)
8.0 parts by weight, 42.0 parts by weight of styrene monomer, 200 parts by weight of calcium carbonate, 1.5 parts by weight of a curing agent, 3.0 parts by weight of zinc stearate, and 1.2 parts by weight of a thickener were mixed, This was a resin composition for SMC. The relationship between the amount of the unsaturated polyester resin, the polymerizable monomer, and the amount of the saturated polyester resin in the SMC resin composition is such that the amount of the unsaturated polyester resin is a part by weight, the amount of the polymerizable monomer is a. B / (a + c) = 1.51, c / a =
0.14. Thereafter, in the same manner as in Example 1, a flat molded product and a flat molded product with a pattern were produced.

The surface smoothness, 60-degree specular gloss, molding shrinkage, and the state of occurrence of glass fiber eyes were examined for the six types of obtained flat molded products. Table 1 shows the results. In addition, surface smoothness and 60-degree specular glossiness of eight types of patterned flat molded products were examined. Table 2 shows the results. The test method was as shown below.

Surface smoothness: Surface smoothness measuring device (US A
shria, Loria (trade name))
The measurement was performed on an area of cm × 20 cm. In addition, the measured value is an index No. The smaller the numerical value, the better the smoothness. Molding shrinkage: The dimensions of the mold and the molded product were measured at 23 ° C. and calculated according to Equation 2. 60-degree specular gloss: According to JIS K 7105, the glass surface having a refractive index of 1.567 was used as a reference surface, and the value in this case was set to 100%, and the 60-degree specular gloss was measured. Occurrence of glass fiber (shown as glass in Table 1):
Observed visually.

[0064]

[Table 1] Example Comparative Example 1 3 1 2 3 4 ────────────────────────────────── Surface smoothness 80 75 120 130 110 120 60 degree specular gloss (% ) 94 93 68 84 80 77 Mold shrinkage (%) -0.01 -0.03 -0.06 0.10 0.05 0.07 Glass grain Small Small Many Many Many Many ──────────────────── ───────────────

[0065]

[Table 2] Example Comparative Example 1 2 3 4 1 2 3 4 ─────────────────────────────────── Surface smoothness 85 83 80 85 125 140 115 130 60 degree mirror surface Gloss (%) 91 90 92 89 65 70 75 71 ───────────────────────────────────

[0066]

According to the present invention, an SMC molded article having excellent surface smoothness and surface glossiness can be manufactured. ADVANTAGE OF THE INVENTION According to this invention, deformation | transformation, such as a warpage and distortion of a molded article after shaping | molding, is hardly formed, and an SMC molded article excellent in design property and excellent in appearance can be manufactured. Therefore, according to the invention described in claim 2,
SM with high design and excellent aesthetics, with a pattern on the surface
C molded products can be manufactured.

The present invention is intended to manufacture members requiring high designability such as housing parts such as wall panels, waterproof pans and counters, as well as automobile parts, electric and electronic parts, and transport equipment parts such as ships, boats and vehicles. It is suitable for.

Claims (3)

[Claims] 1. A prepreg sheet is placed such that the surface side of the prepreg sheet is in contact with a mold surface forming a surface of a molded product, and the molding shrinkage is -0.05 to +0.0.
3% of the sheet molding compound,
A method for producing a fiber-reinforced plastic molded product, comprising heating and pressurizing. 2. The fiber-reinforced plastic molded article according to claim 1, wherein the prepreg sheet is a prepreg sheet having a pattern and a thermosetting resin composition to be a transparent cured product and a fiber base material. Production method. 3. The sheet molding compound according to claim 1,
The unsaturated polyester resin, the polymerizable monomer and the saturated polyester resin as essential components, the compounding amount of the unsaturated polyester resin is a part by weight, the compounding amount of the polymerizable monomer is b parts by weight,
When the compounding amount of the saturated polyester resin is c parts by weight,
A sheet molding compound obtained by using a resin composition for a sheet molding compound in which an unsaturated polyester resin, a polymerizable monomer, and a saturated polyester resin are blended in a range satisfying the formulas (1) and (2). A method for producing a fiber-reinforced plastic molded product according to claim 1 or 2. 0.4 ≦ b / (a + c) ≦ 1.1 (1) 0.3 ≦ c / a ≦ 0.6 (2)