JPH08150628A - Method for producing thermosetting resin molded product - Google Patents

Abstract

(57) [Summary] [Purpose] A method for producing a thermosetting resin molded product used for bathtubs, washstands, kitchen counters, tables, etc., wherein a transparent or semi-transparent surface layer has a backside coloring material. (EN) Provided is a method capable of inexpensively producing a thermosetting resin molded product in which a layer is formed uniformly, overflowing with a feeling of depth and transparency, and a concealing property being secured, without requiring a special mold. [Structure] A back surface layer molding material containing an unsaturated polyester resin, a reinforcing material, and a pigment as main materials is charged into a mold to perform primary compression molding. Then, a surface layer molding material containing an unsaturated polyester resin, a reinforcing material and an inorganic filler as a main material and being transparent or translucent after curing is placed on the surface of the obtained molded product, and the laminate is subjected to secondary compression. By molding and integrating, a thermosetting resin molded product 1 including a transparent or semi-transparent surface layer 2 and a colored back surface layer 3 is formed.

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 molded product.

[0002]

2. Description of the Related Art Conventionally, a resin composition prepared by adding a filler, a curing agent, a release agent, a pigment, a thickener, etc. to an unsaturated polyester resin is impregnated into a reinforcing fiber material such as glass fiber to obtain a bulk material. The molding material in the shape of a sheet or a sheet is called bulk molding compound (BMC) or sheet molding compound (SMC),
It is mainly compression molded and used for bathtubs, washstands, kitchen counters, tables, etc.

In recent years, in order to give a higher quality image, a molded product which gives a transparent feeling when observed from the surface side has been particularly preferred in recent years. Conventionally, a casting method has been used as a method for obtaining a molded product as described above.

[0004]

However, in the casting method, the molding cycle is long and the productivity is low.
It has been switched to the compression molding method.

As a method for obtaining the above-mentioned molded product by the compression molding method, as described in JP-A-5-138674, when a transparent or translucent molded product is in a cured or semi-cured state. , A method of applying a coloring material to the back surface of the molded article and compression-molding again, or a method of injecting the coloring material at a high pressure between the back surface of the molded article and the molding die surface has been proposed. However, since it is easy to cause unevenness because a brush or a spray is used, the latter method requires a nozzle for high-pressure injection and a high-pressure injection device in the mold, resulting in high equipment cost and increase in manufacturing cost. was there.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing a molded article using a transparent or semi-transparent thermosetting resin made of an unsaturated polyester resin, wherein a coloring material for the back surface is used. Layers are formed evenly, giving a sense of depth,
It is an object of the present invention to provide a method capable of inexpensively producing a thermosetting resin molded product that is transparent and secures hiding power without requiring a special mold.

[0007]

In order to achieve the above object, the method for producing a thermosetting resin molded article according to the present invention comprises:
The unsaturated polyester resin, the reinforcing material, and the inorganic filling are applied to the surface of the obtained molded product after the primary layer compression molding by placing the molding material for the back surface layer, which mainly contains the unsaturated polyester resin, the reinforcing material and the pigment. Place the molding material for the surface layer that is made of material as the main material and becomes transparent or translucent after curing,
It is characterized in that the laminate is subjected to secondary compression molding to be integrated.

The method of the present invention will be described with reference to FIG. 1. The thermosetting resin molded article obtained by the method of the present invention will be described.
(1) has a structure in which a transparent or semitransparent surface layer (2) containing an inorganic filler (4) such as glass powder and a colored back surface layer (3) are laminated. This thermosetting resin molded product
When observing (1) from the front side, a colored back layer (3)
It appears to float through the transparent or semi-transparent surface layer (2), providing excellent depth and transparency. Further, the back surface layer (3) is in a uniform state and also has a concealing property.

In the method of the present invention, the unsaturated polyester resin means an unsaturated dibasic acid, a glycol, and optionally an unsaturated polyester obtained by polycondensing a saturated dibasic acid, and a copolymerizable monomer. Is a mixture of. Further, as the resin component contained in the unsaturated polyester,
In addition to the unsaturated polyester, a thermoplastic resin added for reducing the shrinkage may be used.

Here, as the unsaturated dibasic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and the like are used.

As the glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butanediol,
1,4-butanediol, 1,6-hexanediol,
Bisphenol A, hydrogenated bisphenol A, ethylene oxide adduct of bisphenol A, neopentyl glycol and the like are 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 used. The use of styrene is preferred.

The amount of the copolymerizable monomer contained in the unsaturated polyester resin is usually 20 to 50% by weight.

Examples of the thermoplastic resin for reducing the shrinkage include polystyrene, polyvinyl acetate, polymethyl methacrylate, polyethylene, poly ε-caprolactone, saturated polyester, polyvinyl chloride, polybutadiene, styrene-acrylic acid copolymer. , Styrene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, acrylonitrile-styrene copolymer and the like are used.

The inorganic filler to be used in the method of the present invention includes glass powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, barium sulfate, talc, clay, mica, silica, alumina, cold water stone, silica sand. Etc. These may be used alone or in combination of two or more.

In particular, in the surface layer molding material, it is desirable to use glass powder or aluminum hydroxide in order to obtain a deep feeling of the molded product.

The amount of the inorganic filler compounded is in the range of 50 to 360 parts by weight with respect to 100 parts by weight of the unsaturated polyester resin, and the particle size of the inorganic filler is 1 to 30.
μm is preferred.

The reinforcing material used in the method of the present invention is preferably a fibrous material, and examples thereof include glass fibers, organic fibers such as polyester, phenol and vinylon, and carbon fibers. Of these, glass fibers are particularly preferable. Is preferably used. The length of the fibrous reinforcing material is 1 to 8
0 mm is preferred. Here, a short fibrous reinforcing material having a length of less than 1 mm does not have a reinforcing effect, and a fibrous reinforcing material having a length of more than 80 mm is not preferable because the viscosity at the time of compounding increases and the moldability deteriorates.

Particularly, for artificial marble which is excellent in depth,
Glass fibers having a length of 1 to 20 mm, preferably 1.2 to 15 mm are used. In this case, short glass fibers with a length of less than 1 mm have no reinforcing effect, and those with a length of more than 20 mm are
This is not preferable because the appearance of the molded product is impaired.

As the fibrous reinforcing material, in addition to the case where the strand of a constant length is used as it is, a mat-shaped reinforcing material 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 fibrous reinforcing material is mixed in the range of 1 to 40% by weight based on the whole unsaturated polyester resin molding material. Here, if the content of the reinforcing material is less than 1% by weight, there is no reinforcing effect, and if it exceeds 40% by weight, the viscosity of the composition increases and the moldability deteriorates.
Not preferred.

Especially for artificial marble, the amount of the reinforcing material is 1 to 20% by weight, preferably 3 to 15% by weight. Here, if the content of the reinforcing material is less than 1% by weight, there is no reinforcing effect, and if it is more than 20% by weight, the transparency is significantly reduced.

Examples of pigments include titanium oxide (white), quinacridone (red), dioxazine (purple),
Carbon black (black) is used as a color pigment.

The above-mentioned molding material for the surface layer is a resin composition comprising an unsaturated polyester resin, glass fibers, and an inorganic filler, and is usually a curing agent, an internal mold release agent, a thickening agent, and optionally an antioxidant. A bulk molding compound (BMC) is prepared by adding a curing agent, a curing accelerator, a polymerization inhibitor, a pigment and a low-shrinking agent, mixing and kneading with a Henschel mixer or the like, and then integrating them into a bulk.

In this case, in order to prevent volatilization of volatile components of the resin composition, the resin composition is covered with a release film such as a polyester film and aged, usually for 30 to 50 days for 30 to 50 days.
By placing the material under a temperature condition of ° C, it thickens to over 1 million poise and becomes semi-solid, forming BMC. This BMC can be stored in a cool dark place for a long period of time.

As a compounding example of the molding material for the surface layer, 80 to 320 parts by weight of glass powder or 80 to 320 parts by weight of aluminum hydroxide as a filler is added to 100 parts by weight of an unsaturated polyester resin (including a monomer). However, when glass powder and aluminum hydroxide are used in combination, the total amount thereof is 80 to 320 parts by weight, the thickener 0.3 to 3 parts by weight, the internal release agent 1 to 10 parts by weight, and the curing agent 0.5. ~ 3
One part by weight is added, and further, glass fibers are added by 1 to 20% by weight to the whole molding material.

Particularly, as a preferable example of the compound for the surface layer, an unsaturated polyester resin (including a monomer) is used.
100 parts by weight of glass powder 100 as a filler
-300 parts by weight or 0-200 parts by weight of aluminum hydroxide, but when glass powder and aluminum hydroxide are used in combination, the total amount is 100-300 parts by weight, a thickener of 0.8-2 parts by weight, and internal separation. 2 to 5 parts by weight of a mold agent and 1 to 2 parts by weight of a curing agent are added, and glass fibers are further added in an amount of 3 to 15% by weight based on the whole molding material.

According to the molding material of the above formulation example, a surface layer excellent in depth and transparency can be formed.

A back layer molding material containing an unsaturated polyester resin, a reinforcing material and a pigment as main materials is also prepared by the same method as in the case of the above surface layer molding, but the concealing property of the molded product is improved. From the standpoint of ensuring, the molding material for the back surface layer does not particularly require blending of a filler such as glass powder for imparting a feeling of depth and transparency.

The above two molding materials are integrated by compression molding to form a molded product.

That is, first, the backside layer molding material is put into a predetermined mold, the mold is closed, and the backside layer is molded by primary compression molding. After that, the mold is opened, the molding material for the surface layer is placed on the surface of the molded product, the mold is closed again, and the secondary compression molding is performed. As a result, both layers are integrated and a thermosetting resin molded product is obtained.

Here, the presence of the surface layer makes the molded article overflow with a feeling of depth, and the back surface layer can impart the concealing property to the molded article.

The ratio of the thickness of the front surface layer to the back surface layer of the thermosetting resin molded product is preferably in the range of 1: 1 to 1: 0.1 from the viewpoint of ensuring the degree of depth and the concealment. The thickness of the back surface layer is preferably 1 mm or more in terms of molding. The molding temperature is 70 to 160 ° C and the molding pressure is 20 to 150 kgf /
cm ² is preferred.

As the above-mentioned curing agent, t-butylperoxybenzoate, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butyl peroxy-2-ethylhexanoate, 1,1-di-t. Examples thereof include organic peroxides that act on thermosetting resins such as -butylperoxycyclohexane and t-peroxy-isopropyl carbonate.

As the internal release agent, higher fatty acids such as stearic acid and zinc stearate, higher fatty acid salts, alkyl phosphates and the like are used.

The thickening agent is chemically bonded to the hydroxyl group, carboxyl group, ester group, etc. possessed by the unsaturated polyester resin and linearly or partially cross-linked to increase the molecular weight, resulting in unsaturated Thickening polyester resin, for example diisocyanates such as toluene diisocyanate, aluminum isopropoxide,
A metal alkoxide such as titanium tetrabutoxide, an oxide of a divalent metal such as magnesium oxide, calcium oxide, barium oxide, and a hydroxide of a divalent metal such as calcium hydroxide are used.

[0038]

According to the method of the present invention, the molding material for the back surface layer is placed in a mold for primary compression molding, and the molding material for the front surface layer is placed on the surface of the obtained molded product to form a laminate. Since the thermosetting resin molded article is manufactured by the secondary compression molding, not only the molding cycle can be shortened, but also the coloring material layer as the back surface layer can have a uniform thickness. Therefore, when viewed from the transparent or translucent surface layer side, it is possible to obtain a molded product having no unevenness, a feeling of depth and transparency, and a concealing property, and moreover, a conventional resin injection nozzle. A molded product can be manufactured easily and inexpensively using a general-purpose mold that does not require special equipment such as.

[0039]

EXAMPLES Examples of the present invention will be described below.

First, BMC was prepared as a molding material for the surface layer in the following manner.

That is, unsaturated polyester resin 100
Parts by weight (styrene content about 30% by weight), glass powder 1
50 parts by weight, 100 parts by weight of aluminum hydroxide, 13 parts by weight of glass fiber (cut length 3 mm), 1 part by weight of t-butylperoxybenzoate (manufactured by Kayaku Akudo Co., Ltd.) as a curing agent, and zinc stearate as an internal release agent. 3 parts by weight and 1 part by weight of magnesium oxide as a thickener were mixed and kneaded with a Henschel mixer, and the kneaded product was wrapped with polyethylene laminated cellophane and then aged at 40 ° C. for 40 hours for thickening. Then, a bulk molding compound (BMC) was produced.

On the other hand, 100 parts by weight of unsaturated polyester resin and 15 parts by weight of aluminum hydroxide were used as the molding material for the back surface layer.
0 parts by weight, glass fibers 26 parts by weight (cut length 6 mm), white pigment titanium oxide (manufactured by Sumika Color Co., Ltd., trade name; KR-7)
E830), 1 part by weight of tert-butylperoxy-3,5,5-trimethylhexanoate (manufactured by Kayaku Akzo Co., Ltd.) as a curing agent, 3 parts by weight of zinc stearate as an internal release agent, and oxidation as a thickener. 1 part by weight of magnesium was blended, and a BMC for the back surface layer was produced by the same method as the BMC for the front surface layer.

Next, 1 kg of BMC for the back surface layer obtained by the above method was put into a minibus mold heated to 130 ° C. for the upper mold and 115 ° C. for the lower mold, and the molding pressure was 100 kg / mm with a 300 ton press. ² 、 Pressing time 3 minutes, primary compression molding, then open the minibus mold, place 3.5kg BMC for surface layer on the primary molded product in the mold, and clamp again. The laminate was subjected to secondary compression molding under a molding pressure of 100 kg / mm ² and a pressing time of 10 minutes to obtain a thermosetting resin molded product.

Here, the thickness of the surface layer of the obtained thermosetting resin molded article was 6.5 mm, the thickness of the colored back layer was 1.5 mm, and the thickness of the surface layer and the back layer was The ratio of
It was 1: 0.23.

As shown in FIG. 1, the thermosetting resin molded product (1) thus obtained has a transparent or semitransparent surface layer (2) containing glass powder (4) as an inorganic filler. When,
It has a structure in which the colored back surface layer (3) is laminated, and when this is observed from the front side, the colored back surface layer
It was confirmed that (3) seemed to float up through the transparent or semi-transparent surface layer (2), and was excellent in depth and transparency. It was also confirmed that the back surface layer (3), which floats up through the surface layer (2) and is observed, is in a uniform state and has sufficient hiding power.

[0046]

As described above, the method for producing a thermosetting resin molded product according to the present invention is performed by charging the back layer molding material containing an unsaturated polyester resin, a reinforcing material and a pigment as a main material into a mold. Since the molded product for the back surface layer is formed in advance by the primary compression molding, the coloring material layer as the back surface layer can have a uniform thickness. Then, on the surface of the molded product for the back surface layer, the unsaturated polyester resin, the reinforcing material, and the inorganic filler as main materials, and the transparent or semitransparent molded material for the surface layer are placed, and the laminate is laminated. Since a thermosetting resin molded product is produced by subsequent compression molding, a molded product that has no unevenness, a sense of depth and transparency when viewed from the transparent or semitransparent surface layer side, and has concealability. Is what you can get. Moreover, since compression molding is performed using a general-purpose mold that does not require special equipment such as a resin injection nozzle, the molding cycle can be shortened and the equipment cost can be reduced, which results in thermosetting resin. A molded product can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of a thermosetting resin molded product obtained by the method of the present invention.

[Explanation of symbols]

 1: Thermosetting resin molded product 2: Transparent or semi-transparent surface layer 3: Colored back surface layer 4: Glass powder as an inorganic filler

Claims (1)

[Claims] 1. An unsaturated polyester resin is provided on the surface of the obtained molded product after the primary layer compression molding is carried out by introducing a molding material for a back surface layer containing an unsaturated polyester resin, a reinforcing material and a pigment as a main material into the mold. A thermosetting resin comprising a reinforcing material and an inorganic filler as main materials, and a molding material for a surface layer which is transparent or semi-transparent after curing is placed, and a laminate is subjected to secondary compression molding to be integrated. Molded article manufacturing method.