JPH06134783A - Manufacture of molding - Google Patents

Abstract

PURPOSE:To manufacture a molding with favorable superficial characteristics having no sinks or pinholes by blending a reinforcing fiber of 30-70wt.% with respect to the whole of an unsaturated polyester resin molding material, and putting it into a mold to be subjected to a compression molding while applying vibration under heat. CONSTITUTION:An unsaturated polyester resin molding material is made such that a reinforcing fiber of glass fiber or the like is blended in a molding material consisting of adding a curing agent or filling material to unsaturated polyester resin within the range of 30-70wt.% with respect to the whole. Namely, in the case of 30% or more, it is difficult to obtain a dynamic strength and, on the contrary, in the case of 70% or less, it fails to function as a matrix. The molding material is made to flow within the mold, and is subjected to compression molding while applying vibration under heat. Accordingly, air in the inner part of the material or mold is excluded so that a molding can be obtained which has excellent superficial characteristics and has no sinks or pinholes therein, and a molding can also be obtained which has increased fluidity and sufficient strength because of its high content of fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded product using an unsaturated polyester resin molding material.

[0002]

2. Description of the Related Art Thermosetting resin molding material obtained by impregnating a resin composition obtained by adding a curing agent, a thickening agent, etc. to an unsaturated polyester resin into a reinforcing fiber substance such as glass fiber to form a sheet or a bulk. Is called a sheet molding compound (SMC), a bulk molding compound (BMC), or the like, and is mainly compression-molded and widely used for housing equipment, industrial parts, automobile parts and the like.

These unsaturated polyester resin molding materials usually contain about 3 to 25% by weight of reinforcing fibers such as glass fibers. However, for example, a thermosetting resin molding material containing more reinforcing fibers is desired in order to obtain a structural component having higher strength. However, if a large amount of reinforcing fibers is contained, the impregnation property of unsaturated polyester resin will be reduced, and air will remain inside the molding material easily, resulting in a nest (poor filling of molding material in the form of a bird's nest) or pins. There is a problem that holes are easily formed and the fluidity of the molding material is lowered, and in particular, molding is difficult in the case of a complicated molded product having a rib or the like.

To solve this problem, by kneading the unsaturated polyester resin molding material under reduced pressure, the inclusion of air is reduced to prevent or reduce the generation of cavities and the like, whereby the transparency is excellent. A method of manufacturing a molded product has been proposed (see Japanese Patent Laid-Open No. 3-56559). However, in this method, since the polymerizable monomer such as styrene is easily vaporized under reduced pressure, air cannot be sufficiently removed because the degree of vacuum must be adjusted.
Therefore, the formation of cavities and pinholes in the molded product cannot be sufficiently prevented.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to eliminate air sufficiently even with an unsaturated polyester resin molding material having a high content of reinforcing fibers, so that there are cavities and pinholes. The object of the present invention is to provide a method for producing a molded product having excellent surface properties and high strength.

[0006]

According to the method for producing a molded article of the present invention, an unsaturated polyester resin molding material containing a reinforcing fiber of more than 30% by weight and 70% by weight or less is charged into a mold and heated. It is characterized by performing compression molding while applying vibration. The unsaturated polyester resin used in the present invention is an unsaturated polyester obtained by polycondensing an unsaturated dibasic acid, a glycol, and optionally a saturated dibasic acid, and a copolymerizable monomer. . Further, as a resin component contained in the unsaturated polyester resin, a thermoplastic resin may be added, if necessary, in order to reduce the shrinkage, in addition to the unsaturated polyester.

The unsaturated polyester resin molding material used in the present invention is an unsaturated polyester resin containing a curing agent, a thickener, a filler such as calcium carbonate, aluminum hydroxide, calcium sulfate, glass powder and the like, and if necessary. Reinforcing fiber is added to the composition containing release agent, pigment, etc., and is usually integrated in bulk or sheet according to the purpose, covered with a release film such as polyethylene film, and aged to thicken. , Used in a semi-solid state. The bulk type is called BMC, and the sheet type is called SMC. Aging is usually performed by placing the molding material under a temperature condition of 30 to 50 ° C. for half a day to 2 days.

As the unsaturated dibasic acid used for the unsaturated polyester, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and the like are used. As glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol,
Bisphenol A or the like is used. As the saturated dibasic acid, phthalic anhydride, orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, tetrachlorophthalic acid, het acid, etc. are used.

As the copolymerizable monomer, styrene, dichlorostyrene, vinyltoluene, vinyl acetate, methacrylic acid, methacrylic acid ester, acrylic acid, acrylic acid ester, diallyl phthalate, etc. are generally used. Styrene is preferably used.

As the reinforcing fibers, glass fibers, carbon fibers, asbestos fibers, whiskers, organic synthetic fibers, natural fibers and the like are used. In addition to the case where a fiber having a fixed length or continuous fibers is used as it is, a fiber which is previously formed into a mat shape or a shape of a molded product is also used. For example, in the case of glass fiber, a chopped strand obtained by cutting the strand into a certain length, a chopped strand mat in which the chopped strand is bonded with a binder to form a mat, and the like are used.

The length of the fixed length fiber is usually 1 to 80 mm,
It is preferably 20 to 60 mm. As for the directionality of the fibers in the thermosetting resin molding material, in addition to random orientation, orientation in one direction, orientation in X-shape, and the like are used.

The amount of reinforcing fibers in the invention exceeds 30% by weight based on the whole unsaturated polyester resin molding material.
It is mixed in the range of 0% by weight or less. Preferably 35-
It is mixed in the range of 65% by weight, more preferably 40 to 60% by weight. When it is 30% by weight or less, it becomes difficult to obtain the mechanical strength required for structural parts, and when it is more than 70% by weight, the unsaturated polyester resin becomes difficult to function as a matrix.

As the curing agent, a polymerization initiator such as tertiary butyl perbenzoate, benzoyl peroxide, methyl ethyl ketone partoxide, and cumie hydroperoxide, and as a release agent, zinc stearate,
As thickeners such as calcium stearate, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide and the like are used.

Generally, the BMC described above is formed by a mixer such as a kneader, and the SMC is also formed by using a conventionally known device. The SMC or BMC used in the present invention is usually 80-
Put the required amount into the mold heated to 160 ℃,
0 kgf / cm ^2, preferably compression molded at a molding pressure of 10~100kgf / cm ^2.

The method for producing a molded article of the present invention is to flow an unsaturated polyester resin molding material in a mold,
When shaping, compression molding is performed while heating and applying vibration.
As a method of generating vibration, for example, a mechanical system such as a cam / crank system or an unbalanced weight system, an electromagnetic electrical system such as an electrodynamic exciter, or an electrohydraulic system can be used. As the vibration characteristics, the vibration frequency is 20 ~
2000 Hz and a vibration amplitude of 5 to 60 μm are suitable.

[0016]

According to the present invention, more than 30% by weight and 70% by weight
The unsaturated polyester resin molding material containing the following reinforcing fibers is heated and subjected to vibration during compression molding to efficiently remove air inside the material or inside the mold, so that nests and pinholes In addition to obtaining a molded article having excellent surface characteristics, the fluidity is increased and the reinforcing fiber content is high, so that a molded article having excellent strength can be easily obtained.

[0017]

Examples (Examples 1 to 3) 100 parts by weight of an unsaturated polyester resin obtained by dissolving an unsaturated polyester composed of fumaric acid, isophthalic acid and propylene glycol and polystyrene in a styrene monomer (35% by weight of styrene monomer). ) Was mixed with 0.6 part by weight of magnesium oxide, 1 part by weight of t-butylbenzoate, 0.03 part by weight of parabenzoquinone, 5 parts by weight of zinc stearate, and 140 parts by weight of calcium carbonate to obtain a resin composition.

This resin composition was added in the amount shown in Table 1
After mixing with chopped glass strands having a length of 50 mm and a diameter of 13 μm and feeding them to the upper and lower endless belts facing each other at a predetermined interval, the mixture of the resin composition and the glass fiber is sandwiched with an impregnating roll to 40 ° C. It was aged for 1 day to obtain a sheet-shaped molding material (SMC). Using this SMC, Asahi Engineering Co., Ltd. 50t vibration press machine (S
A-50), a flat plate (270 mm × 150 mm × thickness 5 mm) was used to form a flat plate. That is, after inserting SMC into the lower mold of 135 ° C, lower the upper mold of 150 ° C and vibrate the mold three-dimensionally for 20 seconds after the upper mold comes into contact with SMC (frequency is 750Hz, amplitude is 10μm), then 5 minutes, 50kgf / cm
Pressurized at ² .

Bending strength (JIS, K-6911)
Table 1 shows the results of observing the surface condition (presence or absence of cavities and pinholes).

(Comparative Examples 1 to 3) Compression molding was carried out in the same manner as in Examples 1 to 3 except that compression molding was performed without applying vibration.
The results shown in Table 1 were obtained. (Comparative Example 4) Compression molding was carried out in the same manner as in Example 1 except that the glass fiber content was 20% by weight, and the results shown in Table 1 were obtained. (Comparative Example 5) Compression molding was carried out in the same manner as Comparative Example 4 except that compression molding was performed without applying vibration, and the results shown in Table 1 were obtained.

[0021]

[Table 1]

[0022]

According to the present invention, the amount exceeds 70% by weight and 70
An unsaturated polyester resin molding material containing reinforcing fibers in an amount of less than or equal to wt% is put into a mold and heated while applying vibration.
By compression molding, it is possible to easily obtain a molded product having good appearance characteristics and excellent strength without cavities and pinholes.

Claims (1)

[Claims] 1. A molding, characterized in that an unsaturated polyester resin molding material containing reinforcing fibers in an amount of more than 30% by weight and less than 70% by weight is put into a mold and compression molding is performed while heating and applying vibration. Body manufacturing method.