JPS5948029B2 - Method for producing phenolic resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for producing a phenolic resin molding material using a filler pre-treated with hexamine and using a dry production method such as roll or co-kneader, which is the same as conventional methods, such as injection molding. The present invention relates to a method for producing a phenolic resin molding material that does not cause internal defects such as boards in the molded product.

The quality of molded products obtained by molding from phenolic resin molding materials is greatly influenced by the types and amounts of the phenolic resins and base lubricants used, and the mechanical properties of the molded products are affected by these compositions and the flow characteristics of the molding materials. , electrical characteristics etc. are determined. However, depending on the shape of the molded product, mold structure, and other molding conditions, it is often not possible to obtain the same properties even with the same phenolic molding material. This may be due to the orientation of the base material, etc.
There are compositional causes, but internal defects in the boards in the molded product are also causes. That is, internal defects in the board or the like tend to cause variations in strength, and may also cause a significant decrease in electrical properties such as withstand voltage. The present invention relates to a method for producing a phenolic resin molding material that does not cause internal defects such as boards that cause variations in the properties of these molded products.

The present invention aims to eliminate the defects inside the molded product that cause the above-mentioned variations in properties, and is a method for producing a phenol molding material by a conventional method after treating a base material with hexamine in advance. The present invention will be explained in detail below. There are two methods for manufacturing phenolic resin molding materials: a two-step method using novolak resin and curing with hexamine, and a one-step method using resol resin.Also, there are two methods for producing phenolic resin molding materials: a two-step method using novolac resin and curing with hexamine, and a one-step method using resol resin. There is a wet method and a dry method in which raw materials are uniformly mixed with a blender or pen shell mixer, etc., and then kneaded with a roll, co-kneader, etc., but the present invention is a two-step method using hexamine as a hardening agent. The dry method has remarkable effects.

Processing refers to dissolving 1 hexamine in a solvent, mixing it uniformly with 2 filler, drying the solvent 3, and making the filler to which hexamine is attached into a state in which it can be handled as a powder.

Solvents for dissolving hexamine include water, methanol, and chloroform, but water is the best in terms of solubility.

The upper limit of the concentration of hexawater in which hexamine is dissolved in water is about 48% based on the solubility.

Therefore, if the concentration exceeds 45%, precipitation of hexamine may occur, and if such precipitation occurs, large crystals of hexamine will be formed, so an appropriate upper limit of the concentration is 45%. Next, regarding the lower limit of the concentration, the lower the concentration, the more the hexamine can be precipitated and the more uniformly mixed with the filler, but if there is too much water and left to stand after mixing, it will migrate from the upper layer to the lower layer, resulting in non-uniformity. It also becomes difficult to dry. Therefore, a suitable lower limit concentration is 30%, and generally 40% is optimal. The hexa water and the filler are mixed using a conventional wet mixer such as a kneader or a pen shell mixer, the filler is placed in advance, and the hexa water is added while stirring. The amount of hexamine used in the filler is equal to the total amount of hexamine used in the final composition.

The base material treated with hexa water is dried at below 100°C, and the moisture content is adjusted to 5 to 15 (F6). As in the conventional method, this is mixed using a blender, a pen shell mixer, etc., and then a roll, co-kneader, etc. Knead and use as a molding material.

If the water content is more than 15%, partial blockage will occur and uniform mixing will be difficult, while if it is less than 5 (fl), roll kneading etc. will be difficult and the fluidity of the molding material will be poor. Fillers include organic fillers such as wood flour and pulp, and inorganic fillers such as asbestos, calcium carbonate, clay, etc., and the present invention is applicable to all of these fillers.

In addition, alkaline earth metal compounds such as slaked lime, magnesium oxide, and zinc oxide, pigments, mold release agents, and plasticizers such as furfural are used, and conventional compositions can be applied to the present invention as they are.

Hereinafter, the present invention will be specifically explained based on examples.

Example 1 Hexawater was prepared by dissolving 6.3 parts of hexamine in 12.6 parts of water.

Next, 18.9 parts of hexa water was added to 36.2 parts of wood flour, mixed for 10 minutes using a pen shell mixer, and dried at 80° C. for 1 hour to obtain hexa-treated wood flour. Put the above-mentioned hexa-treated wood flour into a pen shell mixer, add 42 parts of novolac resin, 1 part of slaked lime, 1.5 parts of zinc stearate, 2 parts of pigment,
Add 2 parts of furfural and 6 parts of asbestos and mix for 10 minutes to obtain a uniform mixed powder. Next, apply this mixed powder to the front roll 90
The mixture was mixed for 5 minutes at a roll temperature of 80° C. and a rear roll for 5 minutes, and further pulverized to obtain a molding material. Example 2 57 parts of an aqueous solution of Hexamine 40 (F6) was added to 100 parts of wood flour and mixed in a kneader for 30 minutes to make the mixture uniform.

This was dried at 80° C. until the moisture content of the treated material was 10% to obtain hexamine-treated wood flour. Next, 45.5 parts of the above hexamine-treated wood flour, 42 parts of novolak resin, 1 part of slaked lime, 2 parts of pigment, 2 parts of furfural, and 6 parts of calcium carbonate were uniformly mixed in a blender for 30 minutes, and then the front roll was heated to 90°C.
The resulting sheet was kneaded for 5 minutes at a rear roll temperature of 80° C. and the resulting sheet was pulverized to obtain a molding material.

Comparative Example Hexawater was mixed with hexamine at the mixing ratio of Example 1, without being processed into wood flour, and mixed uniformly for 10 minutes in a pen shell mixer, followed by roll pulverization in the same manner to obtain a molding material.

The molding materials of Examples 1 and 2 and Comparative Examples above were molded using an injection molding machine RJ-75A (manufactured by Meiki Seisakusho) at a cylinder temperature of 90°C at the front, 70°C at the rear, and an injection pressure of 50°C at a mold temperature of 180°C.
157 with k9/CflG! Tm square rod-shaped molded product, 47!
A plate with a thickness of 171L was formed, cut, and the presence or absence of the board inside was examined.

After cutting the molded product with a diamond cutter of the first grade and polishing it with sandpaper (#800 to #1500), the size of the board was determined visually or with a microscope at a magnification of 60 to 600.

The results are shown below. Additional Comparative Example The same composition as in the comparative example except for the resin and 10 parts of methanol were placed in a pen shell mixer heated to 100°C, mixed for 5 minutes, and then cooled.

A novolak resin that had been finely ground in advance was added to this mixture, kneaded for 1.5 minutes with heated rolls at 90 to 110°C, cooled, and then ground to obtain a phenolic resin molding material.
Comparative example Number of pieces: 3 to 6 pieces/cm2 Maximum diameter: about 0.1 mm.

Claims (1)

[Claims] 1. A method for producing a phenolic resin molding material, which uses a powdered filler to which hexamine is obtained by dissolving hexamine in a solvent, uniformly mixing it with the filler, and then drying the solvent.