JPH09263655A - Thermosetting resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a melamine resin molding material excellent in tracking resistance and having a small rate of change of size. SOLUTION: This thermosetting resin molding material is obtained by compounding 100 pts.wt. of a thermosetting resin such as a melamine resin or a phenol-modified melamine resin with 2-30 pts.wt. of anhydrous aluminum sulfate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melamine resin molding material having excellent electrical characteristics such as tracking resistance and a small dimensional change rate.

[0002]

2. Description of the Related Art Melamine resin molding materials are used for wiring equipment, electric appliances, etc. due to their excellent tracking resistance, electrical insulation, coloring properties, etc. Since the rate of change is large, cracks, cracks, warps and the like are likely to occur in the molded product, and there are problems in terms of dimensional stability, crack resistance, and the like. In order to improve such a defect, a resol type solid or liquid phenol resin mainly containing a methylol group has been conventionally added to a melamine resin to an extent that the tracking resistance and the coloring property are not impaired. Although this material has a smaller dimensional change rate than a molding material containing only a melamine resin molding material, the present situation is that a sufficient dimensional change rate has not been obtained as compared with a phenol resin molding material. Further, by adding a large amount of an inorganic filler to the melamine resin, the molding shrinkage rate can be improved, but the dimensional change rate after heat treatment cannot be said to be sufficient, and there is a drawback that the specific gravity is large. For these reasons, melamine resin molding materials are not often used in precision molded products that require a high degree of dimensional accuracy, because problems occur during the assembly of parts. Therefore, the melamine resin molding material does not require a high degree of dimensional accuracy, and has been used only for applications in which electrical characteristics such as electric parts and foods that require tracking resistance are absolutely necessary.

[0003]

An object of the present invention is to provide a melamine resin molding material having excellent tracking resistance and a small dimensional change rate.

[0004]

The present invention provides a melamine resin,
Thermosetting resin such as phenol resin-modified melamine resin 10
It is a thermosetting resin molding material characterized by being mixed with 2 to 30 parts by weight of anhydrous aluminum sulfate with respect to 0 parts by weight. The particle size of the anhydrous aluminum sulfate used in the present invention is not particularly specified, but an average particle size of 10 μm or less is preferable. When it is 10 μm or more, the specific surface area is small and the adhesion to the resin is low, resulting in deterioration of mechanical properties.

Since the melamine resin undergoes a condensation reaction in the molding process, the molding shrinkage rate is higher than that of the unsaturated polyester resin and the epoxy resin. In addition, since the number of functional groups is as large as 6 as compared with 3 as in the case of the phenol resin, the molding shrinkage rate is large as compared with the general phenol resin. It is considered that anhydrous aluminum sulfate has an effect as a low shrinkage material because it absorbs water generated during the condensation reaction of the melamine resin and takes it into the molded article to suppress the change in the molding shrinkage rate. The amount of the anhydrous aluminum sulfate compounded is preferably 2 to 30 parts by weight, more preferably 5 to 25 parts by weight, based on 100 parts by weight of the thermosetting resin such as melamine resin and phenol-modified melamine resin. If it is 2 parts by weight or less, the effect as a low shrinkage material is small, and if it is 30 parts by weight or more, the water absorption becomes large and the electrical characteristics deteriorate.

Melamine resins for producing molding materials,
Raw materials used together with thermosetting resins such as phenol-modified melamine resin and anhydrous aluminum sulfate are other inorganic fillers, organic fillers, curing agents, colorants, release agents and the like. The melamine resin used in the present invention may be modified with a phenol resin, an epoxy resin, rubber or the like. Further, a part of the melamine resin may be replaced with a urea resin or the like. The method for producing a molding material using the melamine resin composition may be kneaded with an ordinary mixing roll or a biaxial extrusion kneader,
It may also be granulated by a high-speed rotary mixer. The molding method for obtaining a molded product using the molding material from the melamine resin composition according to the present invention is applicable to any of injection molding, transfer molding, compression molding and the like and is not limited.

[0007]

EXAMPLES The raw materials shown in Table 1 were kneaded in a predetermined mixture by a mixing roll and pulverized to produce a molding material. Bending strength, molding shrinkage, dimensional change after heating, water absorption, tracking resistance (IEC Pub 11
2) was measured. The molding of the test piece was performed by transfer molding, and the molding conditions were 150 ° C. for 3 minutes.

[0008]

[Table 1] * 1: Methylolation degree 1.70, number average molecular weight 300 * 2: Dimethylene ether group 25 mol%, methylol group 15%, number average molecular weight 725 As in the examples, excellent tracking resistance and dimensional change rate A small melamine resin molding material was obtained.

[0009]

According to the present invention, a molded article having excellent tracking resistance and a small dimensional change rate can be obtained. Therefore, it is possible to easily produce a molded article for which the tracking resistance is excellent and the dimension accuracy is required, which could not be produced conventionally, and it is suitable as an industrial melamine resin molding material.

Claims (3)

[Claims] 1. A thermosetting resin molding material comprising 2 to 30 parts by weight of anhydrous aluminum sulfate mixed with 100 parts by weight of the whole thermosetting resin. 2. The thermosetting resin molding material according to claim 1, wherein the thermosetting resin is a melamine resin. 3. The thermosetting resin molding material according to claim 1, wherein the melamine resin is a phenol-modified melamine resin.