JP2001031835A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low specific gravity, low water absorption phenolic resin molding material excellent in wear resistance. SOLUTION: This phenolic resin molding material essentially comprises (a) 60 to 75 wt.% of a high-molecular weight novolak type phenolic resin having a weight-average molecular weight of >=50,000 based on polysthyrene, (b) 5 to 20 wt.% of hexamethylenetetramine as a curing agent and (c) 5 to 35 wt.% of organic filler and/or inorganic filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention provides a phenolic resin molding material which is excellent in abrasion resistance in addition to low specific gravity and low water absorption.

[0002]

2. Description of the Related Art Among thermosetting resins, phenol resins are excellent in various points such as heat resistance, mechanical strength, and electrical properties, and are used for various applications such as molding materials and laminates. Particularly in the heavy electric field, it has been used for breakers and magnet switches for a long time. However, the phenolic resin molding materials used in this application require moldability, appearance, low specific gravity, low cost, etc. There is a problem that the water absorption is high and the electrical insulation property is reduced. On the other hand, a material in which an inorganic filler is blended at a high filling rate has a low water absorption and is excellent in electric insulation, but has a problem that the specific gravity is high and the partner material is significantly worn in the movable part. Not preferred. From such a background, a phenol resin molding material having low specific gravity, low water absorption and abrasion resistance has been desired.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a high-molecular weight novolak phenol resin having a weight average molecular weight of 50,000 or more (hereinafter, "novolak phenol resin" is simply referred to as "novolak resin"). By applying the phenol resin molding material at a high ratio of weight%, a phenol resin molding material having a lower specific gravity, lower water absorption and abrasion resistance than conventional phenol resin molding materials is provided.

[0004]

According to the present invention, (a) 60 to 75% by weight of a high molecular weight novolak resin having a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance, based on the whole molding material; , (B) 5-20% by weight of hexamethylenetetramine as a curing agent, and (c) 5-35% by weight of an organic filler such as wood flour and / or an inorganic filler such as calcium carbonate as essential components. Phenolic resin molding material.

The high molecular weight novolak resin (a) used in the present invention is a polycondensate of a trifunctional phenol and formaldehyde, and has a weight average molecular weight of 50,000 or more when polystyrene is used as a reference substance. In order to make the molding material quick-curing, it is preferable that the methylene bond at the ortho-ortho position relative to the phenolic hydroxyl group is 60% or more of all methylene bonds. Further, from the viewpoint of workability in forming a molding material, the weight average molecular weight is 50,0.
It is preferably from 00 to 200,000.

The amount of the high molecular weight novolak resin added is 60 to
75 parts by weight, preferably 65 to 70 parts by weight. When the amount is less than 60 parts by weight, when the inorganic filler is used, the amount of the inorganic filler is increased, so that the specific gravity is increased and the wear characteristics are reduced. Further, when an organic base material is used, the water absorption increases, and the electrical insulation under high humidity decreases. If the amount exceeds 75 parts by weight, workability in forming a molding material is reduced, which is not preferable in terms of handleability.

In the present invention, hexamethylenetetramine (b) is used as a curing agent in an amount of 5 to 2 with respect to the whole molding material.
Use 0% by weight. If the amount is less than 5% by weight, the curing will be insufficient, and if the amount exceeds 20% by weight, the curability will not be further improved, and conversely, a decomposition gas or the like tends to cause molding failure.

The organic filler and / or the inorganic filler (c) used in the present invention includes wood powder, plywood powder,
Thermosetting resin powder, crushed cloth, etc., and inorganic fillers include, but are not limited to, glass fiber, calcium carbonate, talc, aluminum hydroxide, and the like. The mixing ratio is 5 to 35% by weight based on the whole molding material. If the amount is less than 5% by weight, the effect of improving the abrasion resistance becomes insufficient, and if it exceeds 35% by weight, the fluidity becomes insufficient and molding defects such as blurring tend to occur.

The present invention achieves abrasion resistance, low water absorption and low specific gravity of a molded product by increasing the proportion of a phenolic resin as compared with a normal phenolic resin molding material.
In addition, by using a novolak resin having a high molecular weight as the phenol resin, an appropriate melt viscosity can be obtained when forming a molding material, and good workability can be obtained.

[0010]

The present invention will be described below with reference to examples.

EXAMPLE 1 22.0 kg of phenol was placed in a 50 L high-pressure reactor having a heat exchanger, a heating device and a two-stage turbine type stirring blade of the same diameter, heated to 180 ° C., and heated to 0 ° C. with nitrogen gas. .8
After pressurizing to MPa, the formic acid content was previously reduced to 50P by ion exchange resin treatment with a diaphragm type high pressure metering pump.
13.3Kg of 40% formalin reduced to PM to 60
The mixture was added sequentially from the lower part of the reactor over a period of minutes to cause an addition condensation reaction. The temperature and the addition rate of the jacket of the reactor were adjusted so that the reaction temperature during this time was 180 to 200 ° C. After completion of the addition, the temperature was maintained for 5 minutes, and after confirming that self-heating did not occur, a dehydration reaction was performed while returning to normal pressure over 30 minutes via a heat exchanger while heating to further maintain the temperature at 220 to 230 ° C. Was. Thereafter, the pressure was reduced to 1.3 KPa, and the unreacted phenol was removed for 30 minutes. The unreacted phenol was taken out on a cooling vat to obtain 20.0 kg of a novolak resin having a weight average molecular weight of 52,000 in terms of polystyrene.

A novolak resin having a weight average molecular weight of 52,000, a filler, hexamethylenetetramine, a curing aid, a lubricant, a colorant, and the like are blended in the proportions shown in Table 1 and melt-kneaded with a heating roll to form a molding material. Was done.

Example 2 20.0 kg of phenol was placed in a reactor, 8.9 kg of 88% paraformaldehyde was used as aldehydes, and this paraformaldehyde was previously mixed with 8.0 kg of phenol to form a suspension. Except that the liquid was supplied from the lower part of the reactor with a plunger-type high-pressure metering pump, unreacted phenol was not removed under reduced pressure, and the reaction temperature was 200 to 220 ° C. Novolak resin having a weight average molecular weight of 102,000 in terms of polystyrene, which was reacted in the same manner as in No. 1
7.0 kg was obtained.

A novolak resin having a weight average molecular weight of 102,000, a filler, hexamethylenetetramine, a curing aid, a lubricant, a colorant, and the like are blended in the proportions shown in Table 1 and melt-kneaded with a heating roll to form a molding material. Was done.

Comparative Examples 1 and 2 Novolak resin having a weight average molecular weight of 8,000 in terms of polystyrene (a general phenol resin used for a phenol resin molding material), a filler, hexamethylenetetramine, a curing aid, a lubricant , A colorant, etc., were blended in the proportions shown in Table 1 and melted and kneaded with a heating roll to form a molding material.

With respect to each of the above Examples and Comparative Examples, workability upon forming a molding material was observed. Transfer molding (molding conditions: temperature 180) of the obtained molding material
℃, time 3 minutes) to form a test piece, specific gravity, water absorption,
The wear characteristics were evaluated.

[0017]

[Table 1]

(Measurement method) Specific gravity: Measured according to JIS K7112. 2. Water absorption: JIS K 691 after immersion in normal temperature water for 7 days
Measured according to 1. 3. Abrasion (Sumibe method): Cylindrical molded product 2 having an outer diameter of 18 mm and a width of 10 mm was added to a plate-shaped molded product 1 having a width of 10 mm and a thickness of 4 mm.
The cylindrical molded product 2 was rotated at a speed of 60 rpm while applying a load of 3 kgf as shown in FIG. 1, and the total wear amount of both molded products after 24 hours was measured.

[0019]

As is clear from the results obtained in the above Examples and Comparative Examples, the phenolic resin molding material of the present invention has a lower specific gravity than the conventional phenolic resin molding material.
Since it is a low water-absorbing and low-wear molding material,
It can be suitably used for various heavy electric parts.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a method of measuring a wear amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate-shaped molded product 2 Cylindrical molded product A Load direction B Rotation direction

Claims (1)

[Claims] 1. The weight average molecular weight of (a) polystyrene as a reference substance is 50,0 based on the whole molding material.
High molecular weight novolak type phenol resin 6 having a molecular weight of 00 or more
A phenol containing, as essential components, 0 to 75% by weight, (b) 5 to 20% by weight of hexamethylenetetramine as a curing agent, and (c) 5 to 35% by weight of an organic filler and / or an inorganic filler. Resin molding material.