JP2001062857A - Manufacture of thermosettable resin molded body having silica surface layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a surface height and wear resistance by a method wherein after applying polysilazarane solution to the surface of a heated mold, a thermosettable resin molding material is casted, the mold is closed, and the molding material is cured by heating and compressing. SOLUTION: A chopped strand glass fiber of one inch length is impregnated with a resin paste in which a polyester resin styrene solution 80, a polystyrene styrene solution 20, a calcium carbonate 140, and others in respective pts.wt. are mixed, aged at 40 deg.C for one day to make SMC, and it is applied by blowing 20 wt.% xylene solution of polysilazane by a spray onto the surface of a core mold of the mold heated at 150 deg.C. A thickness of a silica film to be obtained is adjusted so as to become 0.8 μm. After reacting for 1 min, SMC is charged in the mold, the mold is closed, and it is press molded for 4 min by a pressure of 100 kg/cm2. The obtained molded product is treated for 3 h under conditions of 95 deg.C and 80%RH, and silica conversion of polysilazane is completed.

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 article having excellent abrasion resistance on the surface used for a housing interior material, a bathroom substrate, a washbasin substrate and the like.

[0002]

2. Description of the Related Art Conventionally, fiber reinforced plastics (hereinafter referred to as FRs) used for housing interior materials, bathroom base materials, wash basin base materials, and the like.
Press molding using a thermosetting molding material such as a sheet molding compound (hereinafter, referred to as SMC) or a bulk molding compound (hereinafter, referred to as BMC) as a raw material when mass-producing a product (hereinafter referred to as P). The method or the injection molding method is widely industrially performed.

However, such SMC or BMC
Molded products obtained by press molding or injection molding have disadvantages such as insufficient surface hardness and abrasion resistance, easily scratching the surface, and uneven gloss due to scratching. Have.

[0004] Therefore, various methods have been adopted to enhance and improve the surface hardness and abrasion resistance so as not to cause scratches or the like. For example, there is a method of adding a granular additive such as mica powder or glass flake to the thermosetting molding material. In order to improve the surface hardness by this method, it is necessary to add a large amount of a granular additive, and when a large amount of the granular additive is added, the viscosity of the thermosetting molding material increases, and the thermosetting molding at the time of molding is performed. The impregnating property of the resin into the reinforcing fibers (usually glass fibers) contained in the material is reduced. When the impregnation property is reduced, there is a problem that appearance defects are likely to occur in applications such as bathtubs that are exposed to warm water.

In order to solve this problem, Japanese Patent Laid-Open Publication No. 10-1
No. 80972 discloses that a glass bead is used for a resin for gel coating.
A method of dispersing and mixing the particles, applying the resultant to a mold as a surface layer, curing or semi-curing, and then laminating a substrate layer has been proposed, but a molding method using SMC or BMC as a thermosetting molding material has been proposed. Incorporating a method of applying a gel coat to the method causes a problem that productivity is greatly deteriorated, and a problem that it is difficult to mix a glass bead amount sufficient to sufficiently improve the surface hardness remains. ing.

[0006] Polysilazane, which is known to provide a silica film having high abrasion resistance, has poor adhesion to plastic. For this reason, in Japanese Patent Application Laid-Open No. 9-39161,
It has been proposed to provide an adhesive layer in the middle of the plastic layer. However, providing an adhesive layer in FRP molding using SMC or BMC as a thermosetting molding material complicates the process and increases the cost. There is.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the conventional FRP molded article as described above, and has a large surface hardness and abrasion resistance. It is an object of the present invention to provide a method for producing a thermosetting resin molded article having a silica surface layer, which hardly causes cracks, does not cause uneven gloss on the surface due to scratches, and does not reduce glossiness.

[0008]

According to the present invention, after a polysilazane solution is applied to the surface of a preheated mold, a thermosetting resin molding material is charged into the mold, and the mold is closed. A method for producing a thermosetting resin molded article having a silica surface layer, wherein the thermosetting resin molding material is heat-compressed and cured.

The polysilazane of the present invention is -SiH ₂ N
H- is an inorganic polymer that is soluble in an organic solvent having a basic unit. When heated at 140 ° C. to 150 ° C. for 1 to 3 minutes in the air, it reacts with moisture and oxygen to be converted into silica, and has high purity. It forms a dense silica film. The silica film has high abrasion resistance and chemical resistance.

According to the method of evaporating the solvent from the polysilazane solution, it is easy to form a relatively thick silica film, and a film having a maximum thickness of 2.0 μm can be obtained.
If it exceeds 2.0 μm, cracks are likely to occur,
When the thickness is less than 0.1 μm, the durability of the film becomes insufficient. Examples of the organic solvent used in the polysilazane solution include, for example,
Xylene, dibutyl ether, cyclohexane and the like can be mentioned.

In the present invention, press molding or injection molding is used as a molding method for heat-compressing and curing the thermosetting resin molding material. The material used for the molding die is not particularly limited as long as it can withstand the applied temperature and pressure, and examples thereof include steel, aluminum, and nickel electroforming. In the case of press molding, usually 5
It is compression molded at a molding pressure of up to 120 kg / cm ² .

The temperature at which the mold is pre-heated is
Usually, 90 to 160 ° C. is preferable. In the present invention, the polysilazane solution is applied to the surface of the heated mold,
A surface of a molded article (product) obtained by compression molding of a thermosetting resin molding material, which requires abrasion resistance, for example, in the case of a bathtub, the surface of a mold corresponding to the inner surface of the bathtub and the surface of the peripheral portion. Applied.

The method of applying the polysilazane solution is not particularly limited, but a spray method is preferred. After applying the polysilazane solution to the surface of the mold, the time until the thermosetting resin molding material is subjected to press molding or injection molding is such that the solvent is substantially volatilized from the applied polysilazane solution layer, and conversion to silica is performed to some extent. Time to progress is preferred. Depending on the temperature of the mold, a polysilazane having an optimum solvent and reaction rate is selected.

Further, in order to complete the conversion of polysilazane to silica, a molded product obtained by molding is
The treatment is preferably performed in a moist heat environment. As a condition in a moist heat environment, for example, 95 ° C. and 80% RH for 2 to 4 hours is preferable.

As the thermosetting resin molding material used in the present invention, a thermosetting resin, a low-shrinking agent, a glass fiber as a reinforcing fiber, an inorganic filler, and the like can be prepared by a conventionally known method and apparatus for preparing SMC and BMC. It is preferable to use a composition obtained by adding a material, a curing agent, a release agent, a thickener, and further, if necessary, a pigment and an inhibitor to the composition to ripen and thicken it to form SMC or BMC.

The thermosetting resin is a resin generally used in the FRP industry, for example, unsaturated polyester resin, vinyl ester resin, epoxy resin, diallyl phthalate resin and the like. Among them,
Unsaturated polyester resins are preferred because of their good price, viscosity and moldability.

(Function) In the method for producing a thermosetting resin molded article having a silica surface layer according to the present invention, a polysilazane solution is applied to the surface of a preheated molding die, and then the thermosetting resin molding is formed in the molding die. Since the material is charged, the molding die is closed, and the thermosetting resin molding material is heated and compression-cured, the polysilazane is formed into a thermosetting resin molding material during the conversion to silica. And the molded body have good adhesion. The resulting thermosetting resin molded product having a silica surface layer has a high surface hardness and abrasion resistance, and therefore is hardly scratched on the surface. Do not drop. Furthermore, since the surface is excellent in chemical durability, a beautiful surface is maintained for a long time.

[0018]

(Example 1) (Preparation of SMC) 80 parts by weight of a styrene solution of an iso-unsaturated polyester resin and a styrene solution of polystyrene 2
0 parts by weight, 140 parts by weight of calcium carbonate having an average particle size of 2 μm, 1 part by weight of magnesium oxide, 1 part by weight of tert-butyl peroxybenzoate, 0.03 part by weight of parabenzoquinone, and 5 parts by weight of zinc stearate. The mixed resin paste was impregnated with a 1-inch long chopped strand glass fiber and aged at 40 ° C. for 1 day to obtain SMC. The glass fiber content in this SMC was 25% by weight.

(Formation of Silica Film and Molding of SMC) 150
A 20% by weight xylene solution of polysilazane was sprayed onto the surface of a core (a surface corresponding to the inner surface of the resulting bathtub) of a forming die for forming a bathtub heated to a temperature of 0 ° C. The number of spraying was adjusted so that the thickness of the obtained silica film was 0.8 μm. After reacting for 1 minute after the spraying was completed, the SMC was put into the mold, the mold was closed, and press-molded at a pressure of 100 kg / cm ² for 4 minutes. The obtained molded body (bath) was heated at 95 ° C. and 80%
Treatment was performed for 3 hours under RH conditions to complete the conversion of polysilazane to silica.

(Evaluation of Durability) First, the surface gloss of the bath was measured. Then, water was pooled in the bath, and kept at 80 ° C. for 1000 hours with a heating heater to perform a warm water test to measure the surface gloss. Thereafter, using a resin scourer made of vinylidene chloride, an abrasion test of rubbing the surface 10,000 times while applying a load of 5 kg was performed to measure the surface gloss. The results are shown in Table 1.

[0021]

[Table 1]

(Comparative Example 1) Spraying of polysilazane solution
A molded body of a bathtub was obtained in the same manner as in Example 1 except that spray coating was not performed. Then, in the same manner as in Example 1, the surface gloss was measured at the initial stage, after the warm water test, and after the abrasion test. The results are shown in Table 1.

(Comparative Example 2) The same polysilazane solution as used in Example 1 was sprayed on the surface of the molded article obtained in Comparative Example 1 so that the obtained silica film had a thickness of 0.8 μm. The number of times of spraying is adjusted, spray coating is performed by spraying, and after heating at 150 ° C. for 3 minutes, 95 ° C., 80% R
The treatment was performed for 3 hours under the condition of H. Then, as in Example 1, the initial surface gloss, the surface gloss after the warm water test, and the surface gloss after abrasion were measured. The results are shown in Table 1.

As can be seen from Table 1, the molded article of Example 1 having the silica surface layer showed a slight decrease in the initial surface gloss both after the warm water test and after the abrasion test performed thereafter.
The surface was beautiful. On the other hand, the molded article of Comparative Example 1 having no silica surface layer lost its surface gloss both in the warm water test and after the abrasion test. The molded article of Comparative Example 2 in which a silica surface layer was formed in a post-process on the molded article had almost the initial surface gloss after the warm water test, but the adhesion between silica and the molded article was poor. Due to the lack, the surface gloss was lost after the abrasion test.

[0025]

The structure of the method for producing a thermosetting resin molded article having a silica surface layer according to the present invention is as described above. According to the present invention, a molding having good adhesion between the silica film and the molded article is provided. The body is obtained. Therefore, the surface of the molded body has high surface hardness and abrasion resistance, and the surface is hardly scratched, and the scratches do not cause uneven gloss on the surface or reduce the glossiness.

Claims (1)

[Claims] After applying a polysilazane solution to the surface of a preheated mold, a thermosetting resin molding material is charged into the mold, the mold is closed, and the thermosetting resin molding material is heated. A method for producing a thermosetting resin molded article having a silica surface layer, which is compression-cured.