JPS5849745A - Phenolic resin molding compound - Google Patents

Abstract

PURPOSE:The titled molding compound that is made by using mainly spheric form of inorganic filler, thus being suitable for the use in injection molding, because it keeps sufficient fluidity in the cylinder on molding, shows high thermal stability and rapidly solidifies after injected into the mold. CONSTITUTION:A phenolic resin of novolac or resol type or their mixture obtained by using an acid or alkali as a catalyst, is combined with a sphere-formed inorganic filler such as glass beads. As a filler, nonspheric one such as alumina, talc or glass fiber may be used, however, the content of the spheric filler is preferably higher than 50wt%. The friction heat caused by the rotation of the screw in the cylinder is reduced to delay the curing reactions and increase the fluidity of the resin. Thus, its molding operability is improved and at the same time, molding becomes operable even when the content of the filler is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phenolic resin molding material suitable for injection molding.

In recent years, with the expansion of the uses of plastics and the rapid increase in demand, attempts have been made to improve molding efficiency in order to cope with this SC problem. Thermoplastic resin - in this case.

Injection molding has been used for a long time, and molding operations have been carried out under almost satisfactory conditions. On the other hand, with the shift to thermosetting resins, especially phenolic resin molding materials, there is a shift from conventional direct pressure molding to injection molding in order to improve molding efficiency.

However, in the process of molding thermosetting resin,
Heat and pressure - melting and fluidization of the resin and hardening reaction begin simultaneously, and as these two phenomena progress competitively, injection and
While the resin is melted in the cylinder of the molding machine,
Molding may become impossible. In other words, the molding material is heated inside the cylinder, and the temperature of the molding material rises due to the frictional heat generated by the rotation of the screw, causing a curing reaction to proceed and loss of fluidity, which eventually leads to injection molding. It seems impossible.

For this reason, when subjecting a thermosetting resin molding material to injection molding, the temperature of the injection molding machine cylinder is kept at the lowest possible humidity at which the molding material exhibits a molten state to suppress the progress of the curing reaction.

On the other hand, the molding mold is maintained at as high a temperature as possible, and molding conditions are adopted such that -1 temperature curing is completed when the material is injected. However, even if the cylinder temperature is suppressed, the curing reaction proceeds gradually, and the residence time of the molding material in the cylinder becomes longer, and continuous molding occurs over a long period of time.
While doing this, the resin gradually loses its fluidity.
Eventually, a situation arises in which injection molding becomes impossible. Therefore,
As a thermosetting resin molding material for injection molding, the curing reaction does not proceed in the cylinder at a relatively low temperature; in other words, it is melt stable and once injected into the mold, the curing reaction occurs rapidly. Things that have certain characteristics are desired and desirable.

Conventionally, in order to achieve the above-mentioned purpose, attempts have been made to add a large amount of plasticizer to phenolic resin molding materials to ensure low-temperature fluidity. However, the method of using a large amount of plasticizer has the disadvantage that the gloss of the molded product or other various properties deteriorates, and the method of using a molding material in which the resinization reaction is stopped at an early stage. In.

It has the disadvantage that a large amount of volatile matter is generated during molding, and molded products tend to have residue.

The present invention has been made based on one or more of the above circumstances, and it solves the conventional drawbacks, maintains sufficient fluidity in the cylinder during molding, and improves thermal stability. The object of the present invention is to provide a nearly ideal phenolic resin molding material for injection molding, which hardens quickly when injected into a mold.

The present invention is the result of studies on the flow behavior and curing behavior of phenolic resin molding materials.

It has been discovered that in a phenolic resin molding material containing an inorganic filler, if a spherical material is used as the main inorganic filler, the object can be achieved.

The phenol resin used in the present invention may be either a novolac type or resol type resin obtained using an acid or an alkali as a catalyst, or a mixture thereof. What is a spherical inorganic filler?

For example, glass beads having a spherical diameter of jO to 100μ are used. Spherical inorganic filler and chemical alumina.

Karasu powder, talc, clay, glass fiber.

Non-spherical inorganic fillers such as carbon black may be included, and it is preferable that one spherical filler exceeds 500 parts by weight of the total filler.

The phenolic resin molding material of the present invention contains the above-mentioned phenolic resin and inorganic filler, but may also contain an internal mold release agent. Examples of the internal mold release agent include stearic acid, palmitic acid, long chain carboxylic acids such as;

Metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, Cartewax.

Examples include waxes such as montan wax. Other additives include filler treatment agents such as silane coupling agents such as r-aminopropylethoxysilane, and antimony oxide.

Conventionally known additives such as flame retardants such as halides and phosphides, and various pigments may also be blended.

The phenolic resin molding material of the present invention can be obtained by kneading and pulverizing the above-mentioned raw materials using a conventional method such as using a roll. In the present invention, a spherical filler is used as the main inorganic filler, which reduces the generation of frictional heat due to the rotation of the screw in the cylinder of the injection molding machine, suppresses the progress of the curing reaction, and improves the fluidity of the resin. This means that molding operations can be improved. At the same time, in the past, when the amount of inorganic filler was increased, the flow of the molding material became poor, causing problems in molding.

In the present invention, even if the amount of inorganic filler blended is large, the molding operation can be performed.

Next, a detailed explanation of the present invention will be given.

Example 1 Hydrochloric acid catalyzed novolak phenol resin (softening point 95°C
)'11.0 parts by weight [for 1 sll J 1 part of hexa,
Glass peas (ball diameter 10-5 oza) - 30 parts by weight,
Add 120 parts by weight of calcium carbonate, 3 parts by weight of spirit black, and 2 parts by weight of stearic acid.
A molding material was obtained by heating and kneading with a roll at 790°C for 3 to 5 minutes. Table 1 shows the measurement results of the gel time of the molding material, the fluidity of the molding material, and the softening point of the resin.

In addition, in Table 1, the gel time indicates the gel time of the molding material, which was measured using a Brabender plastograph. or.

Fluidity is the value of spiral flow of a molding material. In the following Examples, each item was measured in exactly the same manner.

Example 2 Hydrochloric acid catalyzed novolak phenolic resin (softening point 95°C
) 110 parts by weight, 16 parts by weight of hexa, trade name Microdol (manufactured by Hoechst Gosei Co., Ltd., CaMg(Co
Hatake].

300 parts by weight of spheres with diameters of 2 to 6μ, the main components of which are 70 parts by weight of calcium carbonate, 3 parts by weight of spirit black, and 2 parts by weight of stearic acid, and heated and kneaded at 120°C/90°C for 73 to 5 minutes. A molding material was obtained. Table 1 shows the measurement results of the gel time, fluidity, and softening point of the molding material.

Comparative Example: Novolac type phenolic resin with hydrochloric acid as an electrolyte (softening point: 95°C)
) 110 parts by weight, 15 parts by weight of hexa, 370 parts by weight of calcium carbonate.

3 parts by weight of spirit black and 2 parts by weight of stearic acid were added, and the mixture was heated and kneaded with rolls at 120°C and 790°C for 5 minutes to obtain a molding material.

Table 1 shows the measurement results of the gel time, fluidity, and softening point of the molding material.

Table 1 It can be seen from Table 1 that the molding material of the present invention takes a long time to gel at low temperatures, that is, it has good stability in the cylinder and maintains fluidity for a long time. This effect is unique to the spherical inorganic filler used in the present invention, and although such an effect is not observed with other inorganic materials, the present invention has the advantage of Its industrial value is extremely great, as it has better stability and improves molding workability.

Claims (1)

[Claims] A phenolic resin molding material containing an inorganic filler, characterized in that a spherical material is used as the main inorganic filler.