JP3121655B2 - Phenolic resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenolic resin molding material excellent in molding processability, and more particularly to a phenolic resin molding material which is free from burrs generated during injection molding.

[0002]

2. Description of the Related Art Phenolic resin molding materials have excellent heat resistance, electrical performance, mechanical performance, etc.
It is used for a wide range of applications such as electronic / electric parts and mechanical parts. However, the phenol resin molding material has a problem that burrs are more likely to be generated during the molding process than the thermoplastic resin molding material. Burrs are generated when molten molding material overflows from narrow gaps such as the parting surface of the mold and air vents during molding of the molding material. Therefore, it is strongly desired to reduce or suppress the occurrence of burrs of the phenol molding material.

Conventionally, as a method of solving these problems, a method of compounding a fine powder filler into a molding material is known. The filling of the molding material becomes insufficient, and it is difficult to satisfy both the suppression of burrs and the filling property to the mold. Many solutions have been proposed in terms of mold design and molding machine design and control, but practical solutions are difficult.

[0004]

The present invention has been made as a result of various studies in order to obtain a phenol resin molding material in which burrs are hardly generated at the time of molding. An object of the present invention is to provide a phenolic resin molding material which is extremely excellent in the filling property of phenol resin and in which the generation of burrs is extremely suppressed.

[0005]

SUMMARY OF THE INVENTION The present invention comprises (a) a phenolic resin, (b) a filler, and (c) a phenolic resin having a melting point of 180 ° C. or more, and having a melting point of 180 ° C. or more. A phenolic resin molding material characterized by containing a crystalline phenol compound which melts and is incompatible at a temperature of 180 ° C. or lower (hereinafter referred to as “crystalline phenol compound”) and (d) a nucleating agent.

As the phenolic resin in the present invention, a normal novolak type resin and / or resol type resin obtained by a reaction between phenols and formaldehydes is used. Novolak-type resins can be cured with hexamethylenetetramine, and resol-type resins can be self-cured by heating. Examples of the phenols of the phenol resin include monohydric or polyhydric phenols such as phenol, cresol, xylenol, naphthol, Pt-butylphenol, bisphenol A, and resorcinol, and substituted products thereof. Formaldehyde includes formalin, paraformaldehyde and the like. Further, as the phenolic resin of the present invention, a resin suitably modified with an aromatic hydrocarbon resin, dimethoxyparaxylene, dicyclopentadiene or the like can be used.

As the filler in the present invention, organic substances such as wood powder, pulp powder, pulverized various fabrics, pulverized powder of thermosetting resin laminates and molded products, silica, alumina, aluminum hydroxide, glass, Examples include inorganic powders such as talc, clay, mica, calcium carbonate, and carbon, and inorganic fibers such as glass fiber, carbon fiber, and asbestos, and one or more of these can be used.

The crystalline phenolic compound used in the present invention has a melting point of 180 ° C. or more, and is compatible with the phenol resin before curing at a temperature of 180 ° C. or more, and is incompatible with a phenolic resin at a temperature of 180 ° C. or less. A phenolic compound such as 4,4'-dihydroxybiphenyl,
4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl,
4,4'-dihydroxy-2,2 ', 3,3', 5,5'-hexamethylbiphenyl, 4,4'-dihydroxy-3,3 ', 5,5'-tetra (tert-butyl) biphenyl , 4,4'-dihydroxyphenylsulfone, α, α-bis (4-hydroxyphenyl) -4- (4-hydroxy-α, α-dimethylbenzyl) -ethylbenzene, 4,4 ', 4 "
-Trihydroxy (triphenylethane), 4,4'-dihydroxy-α-methylstilbene, 4,4'-dihydroxystilbene and the like, and one or more of these can be used. Of these compounds, 4,4'-dihydroxybiphenyl is particularly preferred.

As the nucleating agent in the present invention, aluminum dibenzoate, basic aluminum di-p-tert-butyl benzoate, silica, titanium white, alumina, glass powder talc, kaolin, calcium oxide, antimony phosphate, 1.
3,2,4-dibenzylidene sorbitol, 1,3,2,4-ditoluylidene sorbitol, 1,3,2,4-dibenzylidene xylitol, 1,3,2,4,5,6-tribenzylidene sorbitol And the like, and one or more kinds can be used.
Of these nucleating agents, 1.3,2,4-dibenzylidenesorbitol, 1.3,2,4-ditoluylidenesorbitol, 1.3,2,
A nucleating agent selected from 4-dibenzylidene xylitol and 1,3,2,4,5,6-tribenzylidene sorbitol is more preferable.

In the present invention, the mixing ratio of the phenolic resin in the molding material is 35 to 65% by weight, the filler is 35 to 65% by weight, the crystalline phenol compound is 0.5 to 20% by weight, and the nucleating agent is It is 0.01 to 3% by weight. When the compounding ratio of the crystalline phenol compound is less than 0.5% by weight, there is no effect of suppressing burrs, and when it exceeds 20% by weight, the effect does not increase, and various characteristics of the molded article are rather deteriorated. The nucleating agent is used for refining and homogenizing the crystal of the crystalline phenol compound. If the compounding ratio of the nucleating agent is less than 0.01% by weight, there is no effect, and if it exceeds 3% by weight, the properties of the molded article are deteriorated.

The phenolic resin molding material of the present invention is prepared by blending a phenolic resin, a filler, a crystalline phenolic compound, a nucleating agent and various additives as necessary, melt-kneading with a roll mill, a twin-screw kneader or the like, and cooling. , Can be manufactured by grinding.

The very good filling property and the extremely excellent burr-suppressing property in the molding of the phenolic resin molding material of the present invention are based on the fact that uniform and fine crystals of the crystalline phenol compound are present in the phenolic resin of the phenolic resin molding material. This is achieved by: It is essential that the crystals are stable in the resin until the molding at 130-180 ° C is completed.
The crystalline phenol compound of the present invention is used in the form of a powder.However, in order to make the crystalline phenol compound have more uniform and fine crystals in the phenol resin, a method of uniformly mixing and dispersing the phenol compound in the resin in advance is used. preferable. A more preferred method of this method is to melt and mix the novolak resin, the crystalline phenolic compound and the nucleating agent by heating to a temperature at which a transparent molten mixture is formed, cool the mixture and cool the crystalline phenolic compound in the novolak. This is a method of generating fine and uniform crystals, and thereby it is possible to provide the most excellent burr suppressing effect.

In the present invention, when the fine crystals of the crystalline phenol compound in the phenol resin are melted or compatible with the phenol resin, the burr suppressing effect is not exhibited. Further, in order to form microcrystals of the crystalline phenol compound which is preferable due to burr suppression in the phenol resin, it is preferable to melt and mix the phenol resin and the crystalline phenol compound at a temperature equal to or higher than the melting points thereof and cool the mixture. For this purpose, the crystalline phenol compound of the present invention has a melting point of 180 ° C. or higher, is compatible with the phenol resin before curing at a temperature of 180 ° C. or higher, and is incompatible at a temperature of 180 ° C. or lower. .

In the present invention, a nucleating agent is used to assist the formation of fine and uniform crystals of the crystalline phenol compound. If no nucleating agent is used, large crystals of a crystalline phenol compound are generated, and no burr-suppressing effect is exhibited.

In the present invention, additives such as a flame retardant, a colorant, a curing accelerator, and a release agent can be appropriately blended and used as required.

[0016]

The phenolic resin molding material of the present invention has excellent moldability, excellent moldability, excellent moldability with extremely reduced burrs, and especially excellent moldability for injection molding. I have. The reason is that the fine crystals of the crystalline phenolic compound form clusters in the molten resin, and the plasticized phenolic resin molding material has a low viscosity and flows well in the high shear rate region during the plasticization and filling process during molding, and burrs are formed. This is considered to be caused by high viscosity in a low shear rate region in a narrow gap in a place where the fluid is generated, and the fluid does not flow. Furthermore, among the crystalline phenolic compounds, those having reactivity with the curing agent are cured by a cross-linking reaction with the phenolic resin in the curing process, and thus do not adversely affect the properties of the resulting molded product, and have excellent characteristics. Is obtained.

[0017]

The present invention will be described below with reference to examples. Here, "parts" represents parts by weight.

(Example 1) Novolak resin obtained by the reaction of phenol and formaldehyde (average molecular weight 800)
44 parts were charged into a flask and heated to 150 ° C. to melt. 4,4'-dihydroxybiphenyl (melting point 285)
° C) 5 parts, 1,3,3,4-ditoluylidenesorbitol at 0.
Five parts were added and the temperature was raised while mixing. At 252 ° C., the mixture became clear. After cooling, it was pulverized to obtain a powdery opaque resin (A). 7 parts of hexamethylenetetramine powder, 3 parts of calcium hydroxide, 32 parts of wood flour, 11 parts of calcium carbonate, and 3 parts of stearic acid are mixed, melt-kneaded in a two-roll mill, cooled, and ground to form a phenol resin. The material was obtained.

(Example 2) 33 parts of a solid resole resin (average molecular weight: 900) obtained by reacting phenol and formaldehyde with an ammonia catalyst, 11 parts of the resin (A) obtained in Example 1, and 3 parts of calcium hydroxide , 30 parts of wood flour, 11 parts of calcium carbonate, and 3 parts of stearic acid were mixed, melt-kneaded in a two-roll mill, cooled and pulverized to obtain a phenolic resin molding material.

(Comparative Example 1) Novolak resin (average molecular weight 800) obtained by reaction of phenol and formaldehyde 44
Parts, 7 parts of hexamethylenetetramine powder, 3 parts of calcium hydroxide, 32 parts of wood flour, 11 parts of calcium carbonate, and 3 parts of a release agent, melt-kneaded in a two-roll mill, cooled and pulverized to form a phenol resin. A molding material was obtained.

Each of the obtained phenol molding materials was subjected to flowability (melt viscosity) using a Koka type flow tester.
Was measured. Further, molding was performed with a transfer molding machine under the following conditions, and the state of occurrence of burrs was measured. Table 1 shows the results. (Molding conditions by transfer molding machine) 20 g of phenolic resin molding material tableted was preheated to about 100 ° C, and was transferred using a transfer molding die having the shape shown in Fig. 1.
Molded at 175 ° C for 3 minutes. The burr generation state was visually determined for burr at the air vent portion of the mold.

[0022]

[Table 1]

From Table 1, it can be seen that the molding materials obtained in each of the examples are compared with the conventional phenolic resin molding materials of the comparative examples.
It can be seen that, despite having the same fluidity, generation of burrs during molding is extremely small.

[0024]

As is clear from the above examples, the phenolic resin molding material of the present invention can achieve both the filling property in the mold at the time of molding and the suppression of burrs. The man-hour can be remarkably reduced, and it can be widely used as a phenol molding material having excellent moldability.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a transfer mold used in Examples.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 1: Circular cavity 2: Square cavity 3, 4, 5: Air vent 6: Pot 7: Plunger

Claims (2)

(57) [Claims] (1) a phenolic resin, (b) a filler,
(C) Contains a crystalline phenol compound that has a melting point of 180 ° C or higher, is compatible with the phenol resin before curing at a temperature of 180 ° C or higher, and is incompatible at a temperature of 180 ° C or lower, and (d) contains a nucleating agent A phenolic resin molding material characterized in that: 2. The nucleating agent is 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-ditoluylidene sorbitol, 1.3,2,2
The phenolic resin molding material according to claim 1, wherein the phenolic resin molding material is one or more compounds selected from 4-dibenzylidene xylitol and 1,3,2,4,5,6-tribenzylidene sorbitol.