JP2002212388A - Phenolic resin molding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phenolic resin composition that has more improved weld strength and heat impact resistance than the welt strength and heat impact resistance of weak points of conventional phenolic resin materials for pulleys, has excellent mechanical strengths, and is used for automotive parts, general purpose machine parts, domestic electric appliance parts, OA equipment parts, and OA equipment peripheral parts and the like. SOLUTION: This phenolic resin composition used for automotive parts, general purpose machine parts, domestic electric appliance part, OA equipment parts and OA equipment peripheral parts and the like is characterized by comprising a resol type phenolic resin, glass fibers and poly(vinyl acetal) as an organic additive in amounts of 15 to 34 wt.%, 46 to 75 wt.%, and 4 to 10 wt.%, respectively, based on the total amount of the molding material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is excellent in mechanical strength, weld strength and thermal shock resistance, and is suitable for parts for automobiles, parts for general-purpose machines, parts for home appliances, parts for OA equipment and its peripheral equipment and the like. The present invention relates to a phenolic resin molding material used in the present invention.

[0002]

2. Description of the Related Art Conventionally, phenolic resin molding materials used for parts for automobiles, parts for general-purpose machines, parts for household electric appliances, parts for OA equipment and peripheral equipment, etc., are made by mixing glass fiber with mechanical properties due to their required properties. Materials with reinforced strength were used. In addition, a combination of a novolak-type phenol resin and hexamethylenetetramine, which are inexpensive in terms of cost, has been the mainstream. However, in a material containing glass fiber, the mechanical strength is improved, but the anisotropy of the mechanical strength is increased due to the orientation of the glass fiber in the material, and sufficient strength cannot be obtained, or a material such as a weld portion is not provided. There is a problem that the mechanical strength is significantly reduced and the fatigue deterioration is liable to increase in a portion where the reinforcing effect of the glass fiber cannot be obtained. Conventionally, such problems have been improved by the shape of the mold or the gate position and gate shape of the mold cavity in injection molding or transfer molding, but there is a limit to the solution.

[0003] Further, in the combination of a novolak type phenol resin and hexamethylenetetramine, ammonia gas is generated at the time of curing reaction, so that depending on parts, metal may be corroded by residual ammonia generated during use,
In some cases, generation of such gas is environmentally problematic. Further, materials reinforced by glass fibers have high mechanical strength and high elastic modulus, but have a problem that they are weak against thermal shock. On the other hand, in order to impart thermal shock resistance, conventionally, a method has been adopted in which NBR, vinyl acetate or chloroprene rubber is blended and dispersed in a sea-island state to impart resistance to thermal shock. This improved the thermal shock resistance to some extent, but as the number of thermal shock cycles increased, the shock absorbing power at the sea-island area decreased and minute cracks gradually progressed. There was a limit to improve.

[0004]

DISCLOSURE OF THE INVENTION The present invention has excellent weld strength and thermal shock resistance and good mechanical strength as described above, and is suitable for parts for automobiles, parts for general-purpose machines, parts for home appliances, and OA. An object of the present invention is to provide a phenolic resin composition suitably used for equipment and parts for peripheral equipment thereof.

[0005]

Means for Solving the Problems As a result of intensive studies on the above points, the present inventor has found that the use of a phenol resin molding material containing a specific amount of a resol type phenol resin, glass fiber, and polyvinyl acetal makes it possible to obtain a mechanical property. Automotive parts with excellent strength, weld strength, and thermal shock resistance,
The present inventors have found that parts for general-purpose machines, parts for home appliances, parts for OA equipment and peripheral equipment, and the like have been obtained, and the present invention has been completed.

[0006] The automobile parts referred to here include, for example, motor-related parts such as a motor gear case, a motor brush holder, a motor end bracket, a commutator, various bushes, a brake piston, a brake booster, and the like.
General-purpose mechanical parts refer to mechanical parts such as cams and cam pulleys, various pulleys and various gears of small engines, and parts for home appliances include motor brushes, for example. A holder, a motor end bracket, a commutator, a gear, a bearing, and the like are inserted, and the OA device and its peripheral device parts refer to various gears, bearings, and the like, but are not limited to these.

That is, the present invention relates to the entire molding material,
A phenolic resin molding material characterized by containing as essential components 15 to 34% by weight of a resole type phenolic resin, 46 to 75% by weight of glass fiber, and 4 to 10% by weight of polyvinyl acetal as an organic compound.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the resol type phenol resin (hereinafter referred to as resol resin) used in the present invention, a methylol type or a methylene ether type is used alone or in combination. Since a resol type phenol resin (hereinafter referred to as a novolak resin) is a self-curing resin, it can be cured without using hexamethylenetetramine unlike a novolak resin. Therefore, ammonia due to decomposition of hexamethylenetetramine does not remain in the molded product, so that the metal does not corrode or odor due to ammonia gas is not generated, and the thermal shock resistance is improved. Resole resin is 15% of the total molding material.
~ 34% by weight. When the content of the resole resin is less than 15% by weight, there are problems in that production of a molding material becomes difficult and molding becomes difficult because the fluidity of the material is significantly reduced. Therefore, in the weld portion, the adhesion between the resins is poor, and the weld strength is reduced. Further, the modulus of elasticity is increased and the tensile elongation is also reduced, so that the molded article has reduced thermal shock resistance and mechanical strength against repeated fatigue. If it exceeds 34% by weight, the coefficient of linear expansion and the rate of molding shrinkage increase, and the residual stress increases, so that the thermal shock resistance decreases. Further, since the dimensional change due to molding shrinkage and post-shrinkage increases, it becomes difficult to maintain a predetermined molded product size. In consideration of moldability and mechanical strength, it is preferably 20 to 34% by weight.

In the present invention, glass fibers are used as a substrate. The glass fiber is a chopped strand having an average fiber diameter of 6 to 20 μm and an average fiber length of 1 to 6 mm, and is used for a general phenol resin molding material.

In the present invention, glass fibers are used to improve mechanical strength.
If the amount exceeds 5% by weight, the productivity of the material and the moldability in injection molding or transfer molding are undesirably reduced. In addition, the mechanical strength is not improved but is rather lowered. If the amount is less than 46% by weight, the mechanical strength is low, so that the required strength may not be satisfied depending on the molded product, which is not preferable. For this reason, it is preferable that the glass fiber is blended in an amount of 46 to 75% by weight of the whole molding material. In consideration of formability and mechanical strength, the content is preferably 46 to 65% by weight.

[0011] If necessary, an inorganic powder can be used in combination. Examples of the inorganic powder include, but are not limited to, calcium carbonate, wollastonite, kaolinite, clay, fused silica, crystalline silica, mica, aluminum hydroxide, magnesium hydroxide, and diatomaceous earth. Each of these inorganic powders is stable to heat and has a small shrinkage and expansion, so that the coefficient of linear expansion can be reduced and the thermal shock resistance is improved. The amount of the inorganic powder is preferably 1 to 4% by weight based on the whole molding material in order to obtain the above effects. 1% by weight
If the amount is less than 4%, the compounding effect is small, and if it exceeds 4% by weight, the mechanical strength is reduced.

In the present invention, polyvinyl acetal is blended as an organic blend. This is for the purpose of improving thermal shock resistance and mechanical impact strength. As the polyvinyl acetal, one or more of polyvinyl formal, polyvinyl acetoacetal and polyvinyl butyral can be used in combination. Since these partially react with the resole resin and exist in a crosslinked structure, they are independently dispersed in a cured system such as a conventionally used elastomer such as vinyl acetate, NBR, and chloroprene rubber. As compared with the one having the sea-island structure, the thermal shock resistance is less deteriorated due to peeling of the interface between the elastomer component and the resin, and the thermal shock resistance is improved.

When the amount of the polyvinyl acetal is more than 10% by weight based on the whole molding material, the thermal shock resistance is improved due to the reduction of the elastic modulus and the improvement of the tensile elongation. The dimensional change of the molded article due to the increase in the molding shrinkage becomes large, which makes it difficult to obtain a predetermined dimension. Another problem is that the heat resistance, which is a feature of the phenol resin, is impaired. When the amount is less than 4% by weight, it is difficult to reliably improve the thermal shock resistance. Therefore, 4 to 10% by weight of the polyvinyl acetal is blended with respect to the whole molding material.

The method for producing the phenolic resin molding material of the present invention employs a usual method. That is, it is obtained by mixing the above blends at a predetermined blending ratio, further adding a colorant, a release agent, and a curing catalyst, kneading them with a heating roll, and pulverizing the sheet into granules.

[0015]

The present invention will be described below with reference to examples. Table 1
The molding material compositions of Examples and Comparative Examples are shown in FIG. Table 2 shows the results of evaluating the characteristics of the examples and comparative examples.

The compounds used in the examples and comparative examples are as follows. Resole resin: PR-51501B manufactured by Sumitomo Durez Co., Ltd. Novolac resin: PR-50716 manufactured by Sumitomo Durez Co., Ltd. Hexamethylenetetramine: urotropin manufactured by Sumitomo Seika Glass fiber: chopped strand RE manufactured by Nippon Sheet Glass
S Clay: Insulite polyvinyl butyral manufactured by Mizusawa Chemical Co .: Eslek vinyl acetate manufactured by Sekisui Chemical Co., Ltd .: Sakunol manufactured by Denki Kagaku Co., Ltd. Colorant: carbon black Release agent: stearic acid Curing catalyst: slaked lime

These were blended in the proportions shown in Table 1, kneaded between heating rolls, then formed into a sheet and cooled to obtain a granular molding material.

[Table 1]

Test pieces for measuring the characteristics were prepared by injection molding using the obtained molding materials. The molding conditions were a mold temperature of 175 ° C. and a curing time of 1 minute. After the molding, each characteristic was evaluated. Table 2 shows the evaluation results of the molded article characteristics. The representative characteristics of each molding material in Table 2 are based on JIS based on tensile strength and Charpy impact test as mechanical strength.
K 6911 was measured according to "General Method for Thermosetting Plastics", and weld strength was measured according to ISO527 "Tensile Test Method". About the amount of free ammonia, the molded article was measured according to JIS K 7230, "Method for measuring free ammonia". The thermal shock test was conducted with an inner diameter of 45 mm, an outer diameter of 55 mm, and a height of 2.
A molded product obtained by insert molding so as to wrap a 0 mm metal cylinder with a resin portion thickness of 5 mm is put into a thermal shock tester and then subjected to −40.
Between 150 ° C. and 150 ° C. every 30 minutes,
The occurrence of cracks was checked every 50 cycles.

[0019]

[Table 2]

In Examples 1 to 5, the amount of ammonia is extremely small and the thermal shock resistance is excellent as compared with the molding material using the novolak resin shown in Comparative Example 1. Further, it can be seen that the mechanical strength and the weld strength are superior to Comparative Example 2 in which vinyl acetate resin is used as the elastomer. Also,
Compared to Comparative Example 3 with a small amount of glass fiber and Comparative Example 4 with a large amount of resin and a small amount of polyvinyl butyral, mechanical strength and weld strength are excellent. In Comparative Example 5 having a large amount of polyvinyl butyral, the thermal shock resistance and the Charpy impact strength were good, but the tensile strength and the weld strength were small.
It turns out that Examples 1-5 are more excellent.

[0021]

As is clear from the results obtained in the above Examples and Comparative Examples, the phenolic resin molding material of the present invention has higher mechanical strength, weld strength, and thermal shock resistance than conventional phenolic resin molding materials. It turns out that it is excellent. For this reason, it is suitably applied to parts for automobiles, parts for general-purpose machines, parts for home appliances, parts for OA equipment and peripheral equipment thereof, and the like.

Claims (1)

[Claims] 1. Resin-type phenolic resin 15 to 34% by weight, glass fiber 46 to 75% by weight, polyvinyl acetal 4 to 10 as an organic compound, based on the whole molding material.
A phenolic resin molding material characterized in that it is blended as an essential component by weight.