JP2001106867A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phenolic resin molding material which shows excellent insulation and tracking resistance and is usable for a heavy electric part and an electric part. SOLUTION: This molding material comprises a melamine resin (a) having a methylol group, a resol type phenolic resin (b) and an inorganic filler (c) which releases crystalline water at a temperature of not lower than 200 deg.C each as essential components, wherein the ratio of the melamine (a) to the resol type phenolic resin (b) is 0.52<a/b<2.4, (a)+(b) is 30 to 50 wt.%, (c) is 20 to 40 wt.% based on the total of the resin composition, and the residue is other than the inorganic filler (c).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a phenolic resin molding material having excellent tracking resistance.

[0002]

2. Description of the Related Art Phenolic resin molding materials have excellent electrical insulation and heat resistance, and are widely used in heavy electric fields and electric fields. However, with respect to tracking resistance, only lower characteristics can be obtained as compared with resins such as unsaturated polyester resin, melamine resin, urea resin, diallyl phthalate resin and the like. Unsaturated polyester resin and diallyl phthalate resin with good tracking resistance are low in surface hardness, poor in abrasion resistance and scratch resistance, and cause abrasion powder to adhere to the contact parts of electrical components during use and cause poor conduction . Melamine resin has hard and brittle defects. On the other hand, phenol resins are superior to the above resins in terms of hardness, brittleness, continuous moldability, and cost, and improvement in tracking resistance is demanded. This tracking resistance test method is described in IEC. P
ub. Although defined in I.112, there are CTI and PTI with different interpretations of evaluation results. The former is specified to be evaluated by the average of the specified number of tests, while the latter is specified to be evaluated by the lowest value among the specified number of tests. Conventionally, evaluation was performed using CTI, but the situation has shifted to more severe PTI. Therefore,
Even a conventional CTI acceptable product is likely to be rejected by PTI, and further improvement in tracking resistance is demanded. This tracking destruction is a phenomenon in which electric leakage occurs in the presence of light, moisture, and the like, and finally, the surface of the molded product becomes conductive due to carbonization, resulting in surface destruction. A phenol resin is inferior in tracking resistance because it is easily carbonized due to its molecular structure. Therefore, the tracking resistance can be improved by reducing the amount of the phenolic resin that causes surface carbonization and increasing the amount of the inorganic filler, but this is not preferable because it increases the specific gravity, increases the cost, and deteriorates the moldability. In addition, a method of using a powder of an unsaturated polyester resin or a melamine resin having good tracking resistance as a filler has been proposed, but in these methods, a phenol resin is used for the surface layer, so that almost no improvement effect can be expected.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a phenolic resin molding material which has excellent insulation and tracking resistance and can be suitably used for heavy electric parts and electric parts. With the goal.

[0004]

That is, the present invention essentially requires a melamine resin (a) having a methylol group, a resole-type phenol resin (b), and an inorganic material (c) which releases crystal water at 200 ° C. or higher. The ratio of the melamine resin (a) to the resol-type phenol resin (b) is 0.52 <a / b <2.4 by weight ratio, and (a) + (b) is 30 to 50% by weight, (c) is 20 to 40% by weight, and the balance is a filler material other than (c).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The melamine resin having a methylol group used in the present invention preferably has a methylolation degree of 1.0 to 3.0 and a number average molecular weight of 180 to 500, and a methylolation degree of less than 1.0. In this case, the curing reaction is slow.
If it exceeds 0, the gelation is too fast and the kneading operation becomes difficult.
The softening point is not particularly limited, but is preferably 70 ° C. or higher. As methylolated melamine resins, S-176, S
-260 (trade name, manufactured by Nippon Carbide Co., Ltd.) can be used.

Next, the resole type phenol resin to be used includes a methylol type resole resin and a dimethylene ether type resole resin, and both can be used in the present invention. In the former case, since the reaction of the methylol group starts at a low temperature, the thermal stability in the cylinder tends to be slightly deteriorated.
The latter is stable at a low temperature and has a fast reaction at a high temperature, so that it has good thermal stability in a cylinder and quick curing in a mold. However, when combined with a melamine resin having a methylol group, in the former, a more stable tracking resistance can be obtained because the phenol resin and the methylol group of the melamine resin react during kneading of a material such as a roll. The methylol type resole resin can be synthesized by reacting a phenol with formaldehyde in the presence of a normal basic catalyst. As the basic catalyst, ammonia and hexamethylenetetramine are preferable. The methylol type resole resin used in the present invention has a methylol group content of 30 mol%.
A solid resin having a number average molecular weight of 300 to 700 and a mole average molecular weight of 300 to 700 is desirable.

The dimethylene ether type resole resin is obtained by converting phenol and formaldehyde into a salt of a group II element or a transition element with an organic monocarboxylic acid such as formic acid or acetic acid or an inorganic acid such as boric acid, hydrochloric acid or nitric acid. It can be synthesized by reacting. The dimethylene ether type resole resin used in the present invention is preferably a solid resin having a dimethylene ether group content of 20 mol% to 70 mol% and a number average molecular weight of 400 to 1000. The softening point of these resole phenolic resins is not particularly limited, but is preferably 70 ° C. or higher from the viewpoint of workability. If it is less than this, pulverization of the resole type resin becomes difficult, and mixing with other powders such as a filler becomes difficult. The molecular weight of each resin is determined by gel permeation chromatography (GP
By conversion into standard polystyrene using C), the degree of methylolation and the content of dimethylene ether groups can be determined by nuclear magnetic resonance spectrum (NMR). The ratio (a / b) of the melamine resin (a) having a methylol group to the resol-type phenol resin (b) is 0.52 to
2.4 is preferred. If it is less than 0.52, satisfactory tracking resistance cannot be obtained, and if it exceeds 2.4, the molded product becomes brittle. The total amount of the melamine resin having a methylol group and the resol-type phenol resin is preferably 30 to 50% by weight based on the whole phenol resin molding material. If it is less than 30% by weight, the fluidity of the material is poor and the moldability is poor. Also, 50
Exceeding the weight percent results in excessive resin, resulting in high fluidity, poor moldability and reduced tracking resistance. The total amount of the melamine resin having a methylol group and the resole type phenol resin is 3 to the entire phenol resin molding material.
More preferably, it is 5 to 45% by weight.

Examples of the inorganic filler include metal oxides such as aluminum hydroxide, magnesium hydroxide and hydrated alumina; metal hydrates; Use what emits. When these inorganic fillers are used, crystallization water is released when a high voltage is applied during the tracking resistance test, thereby suppressing the rise in surface temperature, making it difficult to form a carbon layer on the surface, and improving the tracking resistance. It is thought that. The particle size of the inorganic filler is not particularly limited, but is preferably 10 μm or less in average particle size in consideration of dispersibility with the resin. Further, the phenolic resin molding material of the present invention includes a conventionally used wood powder, an organic filler such as pulp, an inorganic filler such as calcium carbonate, and an acid,
Hardening accelerators such as alkaline earth metals and alkali salts, template agents, coloring agents, and the like can be used in combination. As a method for manufacturing a molding material, a method similar to a conventional phenolic resin molding material using a heating roll, an extruder, or the like can be applied as it is.

[0009]

The present invention will be specifically described below with reference to examples.・ Synthesis of methylol-type resole resin 1.0 mol of paraformaldehyde and 4 mol of hexamethylenetetramine are mixed with 1 mol of phenol at 50 ° C.
After 10 hours, methanol was added in an amount of 40% by weight to phenol, and the mixture was added dropwise at 100 ° C. and a reduced pressure of 75 mmHg.
A methylol type resole resin having mol%, number average molecular weight of 400 and softening point of 80 ° C. was synthesized.・ Synthesis of dimethylene ether type resole resin 1.2 mol of paraformaldehyde is mixed with 1 mol of phenol, zinc acetate is present as a catalyst in an amount of 0.5% by weight with respect to phenol, and reacted at 100 ° C. for 4 hours. After dehydration at 120 ° C. under reduced pressure, a dimethylene ether type resole resin having a dimethylene ether group content of 55 mol%, a number average molecular weight of 620 and a softening point of 80 ° C. was synthesized. Example 1 Methylolated melamine resin S-260 having a methylolation degree of 2.0 and a number average molecular weight of 320 (manufactured by Nippon Carbide Co., Ltd.)
(Product name) 18 parts, 50 mol% of methylol group, number average molecular weight 400, softening point 80 parts of methylol type resole resin 22 parts, aluminum hydroxide 30 parts, wood powder 28 parts, zinc stearate 1 part, coloring agent 1 The parts were uniformly mixed, kneaded with a roll having a front roll temperature of 90 ° C. to 95 ° C. and a rear roll temperature of 80 ° C. to 85 ° C. for 3 minutes, and pulverized to obtain an actual molding material. Example 2 20 parts of a methylolated melamine resin having a degree of methylolation of 2.0 and a number average molecular weight of 320, 20 parts of a dimethylene ether type resole resin having a dimethylene ether group content of 55 mol% and a number average molecular weight of 620, and aluminum hydroxide 30 Parts, 28 parts of wood flour, 1 part of zinc stearate, and 1 part of coloring agent were produced under the same manufacturing conditions as in Example 1 to obtain a molding material.

Comparative Example 1 20 parts of a methylolated melamine resin having a degree of methylolation of 2.0 and a number average molecular weight of 320, a novolak type phenol resin having a softening point of 92 ° C. containing no methylol group and dimethylene ether group (HP700NK, Hitachi Chemical Co., Ltd.) 20 parts, aluminum hydroxide 30 parts, wood flour 28
Parts, 1 part of zinc stearate and 1 part of a coloring agent were prepared under the same manufacturing conditions as in Example 1 to obtain a molding material. Comparative Example 2 40 parts of a dimethylene ether type resole having a dimethylene ether group content of 55 mol% and a number average molecular weight of 620, 30 parts of aluminum hydroxide, 28 parts of wood flour, 1 part of zinc stearate, and 1 part of a coloring agent The composition was prepared under the same manufacturing conditions as in Example 1 to obtain a molding material. A test molded article was prepared by injection molding using the molding materials of Examples and Comparative Examples,
Tested. The molding conditions at this time were a mold temperature of 180 ° C. and a curing time of 50 seconds by an injection molding machine with a front cylinder temperature of 90 ° C. and a rear cylinder temperature of 80 ° C. The test method is IEC. Pub.
It measured according to 112. For other characteristics, refer to JI
It was measured according to SK6911. The results are shown in Table 1. The number of test samples was 5 and the PTI
Other than that are shown by the average value.

[0011]

[Table 1]

[0012]

According to the present invention, a resole type phenol resin and a melamine resin having a methylol group,
By using an inorganic filler that releases water of crystallization at ℃ or more at a specific ratio, the tracking resistance can be greatly improved, and it is suitable for heavy electric parts and electric parts where insulation and tracking resistance are important. It has become possible to provide a suitable phenolic resin molding material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court ゛ (Reference) C08K 3:34) C08K 3:34) (72) Inventor Hisao Ikegami 1500 Ogawa Oji, Shimodate-shi, Ibaraki Prefecture Hitachi Chemical F-term (reference) in Shimodate Works of Industrial Co., Ltd. 4J002 CC04X CC09X CC18W DE076 DE146 DJ006 DJ036 DJ046 DJ056 FD010 FD016 GQ01

Claims (4)

[Claims] A melamine resin (a) having a methylol group,
It contains a resol type phenol resin (b) and an inorganic filler (c) that releases water of crystallization at 200 ° C. or higher as essential components, and the ratio of the melamine resin (a) to the resol type phenol resin (b) is a weight ratio. 0.52 <a / b <2.4, with (a) + (b) being 30 to 50% by weight, (c) being 20 to 40% by weight, and the balance being (c), based on the total amount of the resin composition. A phenolic resin molding material comprising a filler other than the above. 2. A melamine resin having a methylol group has a methylolation degree of 1.0 to 3.0 and a number average molecular weight of 180 to 500.
The phenolic resin molding material according to claim 1, which is: 3. A resol type phenol resin having a methylol group content of 30 to 80 mol% and a number average molecular weight of 300 to 700.
The phenolic resin molding material according to claim 1, which is a methylol-type resol resin. 4. A resol type phenol resin having a dimethylene ether group content of 20 to 70 mol% and a number average molecular weight of 400.
The phenolic resin molding material according to claim 1, which is a dimethylene ether type resole resin of from 1000 to 1,000.