JPH07290478A - Production of thermosetting resin molded object - Google Patents

Abstract

PURPOSE:To obtain a thermosetting resin molded object free from a void or pinhole and excellent in surface gloss by charging a thermosetting resin molding material prepared by adding a specific amt. of silicic anhydride and a specific amt. of an inorg. filler to a thermosetting resin into a mold and subjecting the same to pressure molding under heating and specific molding pressure while applying vibration to the mold. CONSTITUTION:A thermosetting resin molding material prepared by adding 0.5-15 pts.wt. of silicic anhydride with an average particles diameter 0.5-50nm and 80-350 pts.wt. of an inorg. filler to 100 pts.wt. of a thermosetting resin is charged in a mold. Next, the molding material is subjected to compression molding under molding pressure of 2-30kg/cm<2> while vibration is applied to the mold under heating. At that time, the flowability of the molding material in the mold is greatly increased and the molding material flows while the air in the molding material or in the mold is efficiently excluded and, therefore, a vioid or pinhole is not caused and a molded object having a desired shape is obtained even under a low pressure.

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 thermosetting resin molding.

[0002]

2. Description of the Related Art A resin composition obtained by adding a filler, a curing agent, a release agent, a pigment, a thickener, etc. to a thermosetting resin such as an unsaturated polyester resin or a vinyl ester resin is used as a reinforcing fiber such as glass fiber. Thermosetting resin molding materials that are impregnated with substances and formed into sheets or bulks are available in sheet molding compound (SMC), bulk molding
It is called compound (BMC) and is mainly compression molded and widely used for housing equipment, industrial parts, automobile parts and the like.

[0003]

Conventionally, these molding materials are often compression-molded under heating. The compression molding is performed at a high pressure of 80 to 100 kg / cm ² . In the above-mentioned conventional compression molding method, if the product to be applied is expanded to have a large size and a large variety of products, there is a problem that the cost burden becomes very large due to securing a large molding machine and expensive die investment. there were.

Therefore, if compression molding can be performed at low pressure, the cost burden can be reduced. However, when compression molding is performed at a low pressure, the wall thickness is reduced, the surface gloss is reduced, and
There is a problem that pinholes are easily formed on the surface of the molded body.
For example, if the molded body is used in a bathtub,
The surface gloss is particularly important, and if the gloss level is less than 85, the value as a product is reduced. In the first place, cavities and pinholes not only impair the appearance of the molded product, but also adversely affect the mechanical properties and durability.

Therefore, in order to solve the above problems, as disclosed in Japanese Patent Laid-Open No. 3-56559, the compound is kneaded under reduced pressure, so that a thermosetting resin molding material with less air inclusion is obtained. Have been proposed. However, in this method, since the polymerizable monomer such as styrene is easily vaporized under reduced pressure, it is necessary to adjust the degree of vacuum, and air cannot be removed sufficiently, so that the holes and pinholes are satisfied. It cannot be reduced to the extent possible.

[0006] Further, in order to obtain fluidity at low pressure, a method of molding by lowering the viscosity of the molding material has been attempted.
However, in this method, since the molding material is sticky, there is a problem that the peelability of a release film such as a polyethylene film covering the molding material and the workability such as cutting are deteriorated.

[0007] Further, a method of reducing the pressure inside the mold has been attempted. With this method, although the cavities and pinholes are reduced, not only the fluidity is not obtained, but also the surface gloss is improved. I can't.

It is an object of the present invention that a thermosetting resin molding material can be compression molded at a low pressure and has no cavities or pinholes.
An object of the present invention is to provide a method for producing a thermosetting resin molded product having excellent surface gloss.

[0009]

According to a first aspect of the present invention, there is provided a method for producing a thermosetting resin molded article, wherein 100 parts by weight of the thermosetting resin is used to prepare silicic acid anhydride having an average particle diameter of 5 to 50 nm.
A thermosetting resin molding material containing 5 to 15 parts by weight and 80 to 350 parts by weight of an inorganic filler is put into a mold, and the molding pressure is 2 to 30 k while vibrating the mold under heating.
It is characterized in that it is compression molded at g / cm ² .

According to a second aspect of the present invention, there is provided a method for producing a thermosetting resin molded article, wherein 0.5 to 10 parts by weight of silicic acid anhydride having an average particle diameter of 5 to 50 nm and inorganic are used with respect to 100 parts by weight of the thermosetting resin. Reinforcing fibers are added to a thermosetting resin composition containing 80 to 300 parts by weight of a filler, and the content of the reinforcing fibers is 1 to 4
It is characterized in that a thermosetting resin molding material of 0% by weight is put into a mold, and compression molding is carried out at a molding pressure of ² to 30 kg / cm ² while applying vibration to the mold under heating. .

The thermosetting resin molding material used in the inventions of claims 1 and 2 usually further contains a curing agent, a release agent, a thickener, a pigment and the like, and a stabilizer if necessary. This thermosetting resin molding material is covered with a release film such as a polyethylene film, and usually at 30 ° C. for half a day to 2 days.
The material is aged, thickened and made semi-solid by placing the material under temperature conditions of ~ 50 ° C. The thermosetting resin molding material is formed into a sheet or a bulk according to the purpose.

Examples of the thermosetting resin include unsaturated polyester resin, vinyl ester resin, epoxy resin, and phenol resin. Among them, unsaturated polyester resin and vinyl ester resin are preferable, and thickening,
Unsaturated polyester resins are particularly preferred because of their good moldability. The unsaturated polyester resin is an unsaturated polyester obtained by polycondensing an unsaturated dibasic acid, a glycol, and optionally a saturated dibasic acid, a polymerizable monomer, and optionally a low shrinkage agent for shrinkage. It is a mixture of thermoplastic resins. Examples of unsaturated dibasic acids include maleic anhydride, fumaric acid, itaconic acid and citraconic acid. Examples of the glycol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, hydrogenated bisphenol A, and bisphenol A ethylene oxide. Examples thereof include adducts and neopentyl glycol.

Examples of the saturated dibasic acid include phthalic anhydride, orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, tetrachlorophthalic acid and het acid.

Examples of the polymerizable monomer include styrene, dichlorostyrene, vinyltoluene, vinyl acetate, methacrylic acid, methacrylic acid ester, acrylic acid, acrylic acid ester and diallyl phthalate. Among them, styrene is preferred. .

The amount of the polymerizable monomer contained in the unsaturated polyester resin is usually 20 to 60% by weight. Thermoplastic resins for low shrinkage include polystyrene, polyvinyl acetate, polymethylmethacrylate, polyethylene,
Poly ε-caprolactone, saturated polyester, polyvinyl chloride, polybutadiene, polystyrene-acrylic acid copolymer, polystyrene-polyvinyl acetate copolymer, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, acrylonitrile-styrene Examples thereof include copolymers.

The vinyl ester resin is a resin having a vinyl group at the terminal of an ester chain or an ether chain, and generally refers to an epoxy acrylate resin.

The epoxy acrylate resin is an epoxy acrylate obtained by reacting a bisphenol-type or novolac-type epoxy resin with an unsaturated-basic acid such as acrylic acid or methacrylic acid, a polymerizable monomer and, if necessary, added. It is a mixture of thermoplastic resins for low shrinkage. As the polymerizable monomer and the thermoplastic resin which is added as necessary for reducing the shrinkage, those shown above are used.

Silicic anhydride is represented by the chemical formula SiO ₂ , and its structure is a macromolecule in which tetrahedra of SiO ₄ share all O and are three-dimensionally linked. Both natural ones obtained by crushing silica stone whose main component is silicic acid and those artificially produced by a high temperature hydrolysis method of silicon tetrachloride can be used, but those artificially produced Is preferable in that high purity can be obtained. As the product, Aerosil manufactured by Nippon Aerosil Co., Ltd. is used.

The silicic acid anhydride used in the present invention is an ultrafine powder having an average particle size of 5 to 50 nm, preferably 7 to 40 nm. If the average particle size is less than 5 nm, the viscosity is significantly increased, and it becomes difficult to uniformly mix the filler and the resin, and the mechanical properties are deteriorated. If the average particle size is more than 50 nm, the effect of improving the fluidity due to vibration is obtained. Less and more prone to meat loss

In the invention of claim 1, the amount of silicic acid added is 0.5 to 1 with respect to 100 parts by weight of the thermosetting resin.
5 parts by weight, preferably 0.8 to 10 parts by weight. The addition amount of silicic acid anhydride in the invention of claim 2 is 0.5 to 10 parts by weight, preferably 0.8 to 7 parts by weight with respect to 100 parts by weight of the thermosetting resin.

In the present invention, the amount of silicic anhydride added is
If the amount is less than 0.5 part by weight, the effect of improving fluidity at the time of compression molding cannot be obtained while applying vibration. In addition, in the invention of claim 1, when the amount of silicic acid added is more than 15 parts by weight, thixotropy becomes too high, rather the vibration effect is lowered, the viscosity is greatly increased, and a filler is used. The uniform mixing with the thermosetting resin becomes difficult and the mechanical properties decrease, and in the invention of claim 2, the addition amount of silicic anhydride is
If the amount is more than 10 parts by weight, the viscosity is significantly increased, impregnating property with the reinforcing fiber is lowered, and voids are generated in the molded product or mechanical properties are deteriorated.

When silicic acid anhydride is added to the thermosetting resin,
Thixotropic can be imparted. In addition, thermosetting resin 1
00 parts by weight is the total amount of a polymer (oligomer) component such as unsaturated polyester and epoxy acrylate, and a polymerizable monomer and a thermoplastic resin for reducing shrinkage, which is added if necessary. As the inorganic filler, calcium carbonate, aluminum hydroxide, calcium sulfate, glass powder, talc, mica and the like are used.

The addition amount of the inorganic filler in the invention of claim 1 is 80 to 350 parts by weight, preferably 100 parts by weight of the thermosetting resin, whether used alone or in combination. Is in the range of 100 to 300 parts by weight,
The addition amount of the inorganic filler in the invention of claim 2 is 80 to 300 parts by weight with respect to 100 parts by weight of the thermosetting resin. It is preferably 100 to 270 parts by weight.

In the present invention, the addition amount of the inorganic filler is 8
When the amount is less than 0 parts by weight, the effect of increasing the fluidity due to vibration is small, and the thickness tends to be thinned. Further, in the invention of claim 1, when the addition amount of the inorganic filler is more than 350 parts by weight,
In the invention according to claim 2, the viscosity is significantly increased, the uniform mixing of the filler and the resin becomes difficult, and the mechanical properties are lowered.
When the amount of the inorganic filler added is more than 300 parts by weight, the viscosity is significantly increased, impregnating ability with the reinforcing fiber is lowered, and a cavity is generated in the molded product, or mechanical properties are deteriorated.

The preferred particle size of the inorganic filler is 0.1-2.
It is 00 μm. As the curing agent, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy 3,5,5-trimethylhexanoate, 1,1
-Bis (tertiary butyl peroxy) 3,3,5-
Examples thereof include organic peroxides such as trimethylcyclohexane, benzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide and the like.

Examples of the releasing agent include zinc stearate and calcium stearate. As a thickener,
Examples thereof include magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide and the like. As a stabilizer,
A phosphite-based antioxidant is added as necessary to reduce yellowing during molding or hot water immersion, but a solid phosphite-based antioxidant with less curing retarding action is suitable. .

As the reinforcing fibers in the invention of claim 2, glass fibers, carbon fibers, asbestos fibers, whiskers, organic synthetic fibers, natural fibers and the like are used. The reinforcing fiber is used after being cut into a certain length or as a continuous fiber. In addition, mats and cloths are 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 fixed length is usually 1 to 80 mm. If the fiber length is shorter than 1 mm, there is no reinforcing effect, and if it is longer than 80 mm, the viscosity increases and the moldability deteriorates. The direction of the fibers in the thermosetting resin molding material may be random, in addition to being arranged in one direction, arranged in an X shape, or the like, and the direction that is appropriate for the application is used. To be done.

The content of the reinforcing fiber is 1 to 40% by weight, preferably 3 to 35% by weight based on the whole thermosetting resin molding material.
It is mixed in the range of wt%. If the content of the reinforcing fibers is less than 1% by weight, there is no reinforcing effect, and if it is more than 40% by weight, the viscosity increases and the fluidity deteriorates.

The sheet-shaped molding material is formed by using a known machine. For example, a thermosetting resin composition is applied to a release film such as a polyethylene film with a doctor blade so as to have a uniform thickness, and then the release film is covered with an upper surface of the thermosetting resin composition. When reinforcing fibers are added, the reinforcing fibers are sprinkled on the surface coated with the thermosetting resin composition, and the reinforcing fibers are impregnated with the thermosetting resin by a roll to form a sheet. The bulk molding material is formed by a mixer such as a kneader.

The sheet-shaped or bulk thermosetting resin molding material is usually put in a required amount in a mold heated to 60 to 160 ° C., and the molding pressure is ^{2 to} 30 kg / cm ² , preferably 5 to 5. It can be molded at 20 kg / cm ² . 2 kg
If it is less than / cm ² , the vaporization of the polymerizable monomer cannot be suppressed, and the physical properties of the molded article are deteriorated. If it is more than 30 kg / cm ² , the effect of vibration is small.

The time for applying vibration to the mold is usually from the moment when the thermosetting resin molding material is placed in one of the female mold and the male mold and then the other mold comes into contact with the molding material. , Until the molding material loses fluidity.

The vibration characteristic is that the vibration frequency is 20 to 5
The amplitude is 2 to 60 μm at 000 Hz, but the vibration frequency is 500 to 500 due to the balance between the effect of vibration and the durability of the mold.
The amplitude is preferably 5 to 30 μm at 3000 Hz.

The direction of vibration may be vertical, horizontal, or three-dimensional vibration, but three-dimensional vibration is suitable for obtaining a molded product having a three-dimensional shape.

As a method of generating vibration, 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.

A preferred example of the invention of claim 1 will be described below. As the thermosetting resin, 0.8 to 10 parts by weight of silicic acid anhydride having an average particle size of 7 to 40 nm is used per 100 parts by weight of the unsaturated polyester resin, and as the inorganic filler, carbonic acid having an average particle size of 0.5 to 20 μm. Any one of 100 to 300 parts by weight of calcium, 100 to 300 parts by weight of aluminum hydroxide having an average particle size of 0.5 to 30 μm and 100 to 300 parts by weight of glass powder having an average particle size of 0.5 to 20 μm is added. When a plurality of these are used in combination, an unsaturated polyester composition is obtained by adding them so that the total weight is 100 to 300 parts by weight.

In the unsaturated polyester composition having the above composition, 0.2 to 2.0 parts by weight of organic peroxide as a curing agent and 2 to 10 parts by weight of zinc stearate as a release agent,
As a thickener, 0.2 to 3 parts by weight of magnesium oxide is mixed and aged to obtain a thermosetting resin molding material. This thermosetting resin molding material is put into a mold heated to 80 to 160 ° C., the mold is closed, and when the molding material comes into contact with both molds, the vibration frequency is 500 to 3000 Hz and the amplitude is 5 to 3
Vibration of 0 μm is applied for 5 seconds to 5 minutes, molding pressure 5 to 20 k
Compression molding was performed at g / cm ² to obtain a thermosetting resin molded body.

A preferred example of the invention of claim 2 will be given below. As the thermosetting resin, the average particle size is 7 to 40 nm with respect to 100 parts by weight of the unsaturated polyester resin.
0.8 to 7 parts by weight of anhydrous silicic acid, and calcium carbonate 100 to 27 having an average particle size of 0.5 to 20 μm as an inorganic filler.
0 parts by weight, 100 to 270 parts by weight of aluminum hydroxide having an average particle size of 0.5 to 30 μm, and an average particle size of 0.5 to 20 μm
Any one of 100 to 270 parts by weight of m glass powder
When a plurality of types are used in combination, the unsaturated polyester composition is obtained by adding them so that the total weight is 100 to 270 parts by weight.

In the unsaturated polyester composition having the above composition, 0.2 to 2.0 parts by weight of an organic peroxide as a curing agent, 2 to 10 parts by weight of zinc stearate as a release agent,
As a thickener, 0.2 to 3 parts by weight of magnesium oxide is mixed, and reinforcing fibers are added to the entire amount of the molding material in an amount of 3 to 35% by weight using an SMC or BMC manufacturing apparatus, followed by aging. Then, a thermosetting resin molding material is obtained. This thermosetting resin molding material is put into a mold heated to 80 to 160 ° C., the mold is closed, and when the molding material comes into contact with both molds, the vibration frequency is 500 to 3000 Hz and the amplitude is 5 to 5.
Vibration of 30 μm is applied for 5 seconds to 5 minutes, and pressure is 5 to 20 kg.
/ Cm ² was compression-molded to obtain a thermosetting resin molded body.

[0039]

According to the present invention, since the thermosetting resin molding material contains silicic acid anhydride, it has thixotropic properties, and since it has a low viscosity due to vibration, the flow of the molding material in the mold is suppressed. As the molding material flows while efficiently excluding air inside the molding material or inside the mold, cavities and pinholes do not occur, and the molded body of the desired shape can be treated under low pressure conditions ( ^{2 to} 30 kg / cm ² ) can also be obtained.

Further, according to the present invention of claim 2, a molding material having excellent mechanical properties can be obtained even under a low pressure condition by including reinforcing fibers in the molding material.

[0041]

EXAMPLES In the following examples, the average particle size of silicic acid anhydride was calculated by enlarging the primary particle size magnification to 50,000 to 400,000 times using a scanning electron microscope. First, an embodiment of the invention of claim 1 will be described. Examples 1 to 4 100 parts by weight of an unsaturated polyester resin in which an unsaturated polyester composed of fumaric acid, isophthalic acid and propylene glycol and polystyrene are dissolved in a styrene monomer is added to a silicic acid anhydride (Nippon Aerosil) having an average particle diameter of 12 nm. Aerdir # 200 manufactured by K.K., aluminum hydroxide (average particle size 8 μm) shown in Table 1, magnesium oxide 1 part by weight, tertiary butyl peroxybenzoate 1 part by weight, rose benzoquinone 0.03 part by weight, stearin A thermosetting resin composition prepared by mixing 5 parts by weight of zinc oxide was added to 4 parts.
Aged at 0 ° C for 1 day to obtain BMC.

Using this BMC, a flat plate (270 mm × 150 mm × thickness 2 mm) mold was molded at a molding pressure shown in Table 1 by a 50t vibration press machine (SA-50) manufactured by Asahi Engineering Co., Ltd.

The vibration was started for 20 seconds after the molding material came into contact with the upper and lower molds. The charge was placed in the corner on the short side of the flat plate mold, and the charge area ratio was about 11%. The pressing time was 3 minutes. The mold temperature was 150 ° C. for the upper mold and 135 ° C. for the lower mold.

As an evaluation item of the molded product, the fluidity is indicated by the filling area ratio of the molding material to the projected area of the flat plate die, and the glossiness of the obtained molded product is measured and the surface condition is observed (for nests and pinholes). Existence). Gloss is JI
According to SK7105, a 60-degree specular gloss was measured with a gloss meter.

Comparative Examples 1 to 7 Compression molding was carried out in the same manner as in Examples except that the addition amount of silicic acid anhydride, the particle size, the addition amount of aluminum hydroxide, the molding pressure, and the presence or absence of vibration were as shown in Table 1. The results shown in Table 1 were obtained.

[0046]

[Table 1] Next, an embodiment of the invention of claim 2 will be given. Examples 5-8 100 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 was added to anhydrous silicic acid (Nippon Aerosil) having an average particle size of 7 nm. Aerdir # 300 manufactured by K.K., calcium carbonate (average particle size 2 μm) in the amounts shown in Table 2 and magnesium oxide 1
Parts by weight, tertiary butyl peroxybenzoate 1
25 parts by weight of a thermosetting resin composition in which 0.03 parts by weight of rose benzoquinone and 5 parts by weight of zinc stearate are mixed.
mm chopped strands were impregnated and aged at 40 ° C. for 1 day to obtain SMC. The glass content is as shown in Table 2.

Using this SMC, a flat plate (270 mm × 150 mm × thickness 2 mm) mold was molded at a molding pressure shown in Table 2 by a 50t vibration press (SA-50) manufactured by Asahi Engineering Co., Ltd.

The vibration was started for 20 seconds after the molding material came into contact with the upper and lower molds. The charge was placed in the corner on the short side of the flat plate mold, and the charge area ratio was about 11%. The pressing time was 3 minutes. The mold temperature was 150 ° C. for the upper mold and 135 ° C. for the lower mold.

As an evaluation item of the molded product, the fluidity is shown by the filling area ratio of the molding material to the projected area of the flat plate die, and the glossiness of the obtained molded product is measured and the surface condition is observed (for nests and pinholes). Existence). Gloss is JI
According to SK7105, the 60-degree specular gloss was measured with a gloss meter.

Comparative Examples 8 to 15 Addition amount of silicic acid anhydride, particle size, addition amount of calcium carbonate,
Compression molding was carried out in the same manner as in Example except that the addition amount of glass fiber, the molding pressure, and the presence or absence of vibration were set as shown in Table 2.
The results shown in are obtained.

[0051]

[Table 2]

[0052]

EFFECTS OF THE INVENTION According to the present invention, a thermosetting resin molding material can be compression-molded at a low pressure into a molded product having a desired shape. Since an excellent molded body can be easily obtained, there is an advantage that the molded body can be made large in size and various kinds can be manufactured at low cost, and the molding width can be widened.

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Claims (2)

[Claims] 1. A thermosetting resin molding containing 0.5 to 15 parts by weight of silicic acid anhydride having an average particle diameter of 5 to 50 nm and 80 to 350 parts by weight of an inorganic filler with respect to 100 parts by weight of the thermosetting resin. A method for producing a thermosetting resin molded product, which comprises charging a material into a mold and performing compression molding at a molding pressure of ² to 30 kg / cm ² while applying vibration to the mold under heating. 2. A thermosetting resin composition containing 0.5 to 10 parts by weight of silicic acid anhydride having an average particle size of 5 to 50 nm and 80 to 300 parts by weight of an inorganic filler with respect to 100 parts by weight of the thermosetting resin. Reinforcement fiber is added to the product, and the content of reinforcement fiber is 1 to 4
A thermosetting resin, which comprises 0% by weight of a thermosetting resin molding material and is compression molded at a molding pressure of ² to 30 kg / cm ² while vibrating the mold under heating. A method for producing a resin molded body.