JP2005272654A - Phenol resin molding material for commutator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin molding material for commutators capable of providing a commutator having small difference of anisotropy and even long-term dimensional change while keeping mechanical properties, compared with conventional commutator made of phenol resin and excellent in roundness thereby, largely improved in toughness and excellent also in press-fittability. <P>SOLUTION: The phenol resin molding material for commutators comprises 25-50 wt.% phenol resin, 5-15 wt.% talc, 5-15 wt.% calcium carbonate, 20-55 wt.% glass fiber and 5-30 wt.% one or more kinds of material selected from clay and wollastonite. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

   The present invention relates to a phenol resin molding material for a commutator.

  The glass resin-containing phenol resin molding material is excellent in heat resistance, dimensional stability, moldability, etc., and has a track record of being used for a long time in key industries such as the automobile field, the electric field, and the electronic field. In recent years, there has been a demand for further improvement of the properties of glass resin-containing phenolic resin molding materials. In particular, in the field of key parts such as automobile parts, not only mechanical strength at room temperature but also machine at heat It is necessary to improve the mechanical strength, suppress the deterioration due to heat, and reduce the dimensional change.

  Among these, basic properties required for materials used for commutators include heat resistance such as mechanical strength during heat and dimensional stability during heat, and moisture dimensional stability. In particular, with respect to the dimensional stability, there is a distortion caused by a deviation in the roundness of the commutator due to a dimensional change caused by a difference in linear expansion coefficient (anisotropic difference) caused by orientation of glass fibers or the like when the material flows. In addition, commutators used in small motors often have excellent toughness so that the commutator does not break during press-fitting because a shaft that is slightly thicker than the inner diameter is directly press-fitted into the inner diameter of the commutator molded with a phenol resin molding material. Required.

  For example, Patent Literature 1 discloses a filler for a phenol resin molding material for a commutator. However, there is no description regarding the balance between strength (toughness) and dimensional stability.

JP-A-9-95595

  Compared to conventional phenol resin commutators, the present invention is superior in roundness due to its small anisotropic difference and uniform long-term dimensional change, while maintaining mechanical properties, and greatly improves toughness and press fit. In addition, the present invention provides a phenol resin molding material for a commutator that can provide an excellent phenol resin commutator.

Such an object is achieved by the present invention described in the following (1) to (2).
(1) A phenol resin molding material for a commutator, which is 25 to 50% by weight of phenol resin, 5 to 15% by weight of talc, 5 to 15% by weight of calcium carbonate, and 20 of glass fiber with respect to the entire molding material A phenol resin molding material for a commutator, comprising: -55% by weight and 5-30% by weight of at least one selected from clay or wollastonite.
(2) The phenol resin molding for a commutator according to the above (1), wherein one or more average particle diameters selected from the above talc, calcium carbonate, and clay or wollastonite are 30 to 100 μm. material.

  The phenol resin molding material for commutator of the present invention is 2 to 50% by weight of phenol resin, 5 to 15% by weight of talc, 5 to 15% by weight of calcium carbonate, and 20 to 55% of glass fiber with respect to the whole molding material. It is characterized by containing 5 to 30% by weight of one or more selected from clay or wollastonite, and has the same mechanical properties as conventional commutator molding materials. Above that, since the anisotropic difference of the linear expansion coefficient is small and the improvement of toughness is obtained, a phenol resin commutator having excellent circularity and excellent press-fitting properties can be obtained.

Hereinafter, the present invention will be described in detail.
The present invention comprises 25-50% by weight of phenolic resin, 5-15% by weight of talc, 5-15% by weight of calcium carbonate, 20-55% by weight of glass fiber, and clay or It is a phenol resin molding material for a commutator characterized by containing 5 to 30% by weight of one or more selected from wollastonite.

As the phenol resin used in the present invention, a novolac type or a resol type may be used alone, or both may be used in combination. Although it does not specifically limit about novolak type phenol resin, For example, random novolak resin and high ortho novolak resin are mentioned. Among these, the one having a number average molecular weight of 800 to 1,000 is used, the workability at the stage of forming a molding material, the moldability (especially injection molding) is good, and the mechanical properties of the obtained molded article are good. It is preferable at this point.
The resol-type phenol resin is not particularly limited, and examples thereof include a methylol type and a dimethylene ether type. Among these, it is preferable to use a dimethylene ether type because of a good balance between curability and thermal stability. .

  When a novolac type phenol resin is used, it is usually preferable to blend 15 to 25% by weight of hexamethylenetetramine as a curing agent with respect to the phenol resin. If it is less than the lower limit, curing may be insufficient, and even if it exceeds the upper limit, the curability will not be improved any more, and conversely, it may cause molding defects due to decomposition gas or the like. is there.

  The content of the phenol resin used in the present invention is 25 to 50% by weight with respect to the entire molding material including hexamethylenetetramine when it is blended. If the content of the phenolic resin is less than the lower limit, the flow as a molding material may not be sufficient, and if the content exceeds the upper limit, the content of the inorganic base material such as glass fiber is reduced, resulting in heat resistance and dimensions. The commutator characteristics such as stability may not be satisfied.

  The molding material of this invention contains the talc which is an inorganic base material. By containing talc, it becomes possible to reduce the anisotropic difference of molded products, such as a commutator obtained. The reason for this is not clear, but talc is considered to have an action of reducing the anisotropy manifested by the glass fiber because the shape is plate-like and the smoothness in the surface direction is large.

  It is preferable to use talc having an average particle size of 30 to 100 μm. Furthermore, 35-55 micrometers is preferable. If the average particle size is less than the lower limit value, the effect of reducing the anisotropic difference is less likely to appear, and if the upper limit value is exceeded, the mechanical strength may be reduced, and workability at the stage of forming the molding material may be reduced. is there.

  The content of this talc is 5 to 15% by weight with respect to the entire molding material. If the talc content is less than the lower limit value, the effect of reducing the anisotropic difference of the commutator molded product may be insufficient. If the upper limit value is exceeded, the workability during the production of the molding material is reduced and the machine of the molded product is reduced. There is a case where a decrease in the mechanical strength occurs.

  The molding material of this invention contains the calcium carbonate which is an inorganic base material. By containing calcium carbonate, it becomes possible to improve the toughness (pressability) of a molded product such as a commutator obtained.

The calcium carbonate content is 5 to 15% by weight based on the entire molding material. If the content of calcium carbonate is less than the lower limit value, the effect of toughness expression of the commutator molded body may be insufficient, and if the upper limit is exceeded, the strength of the commutator molded body may decrease.
The average particle size of the calcium carbonate is not particularly limited, but is preferably 30 to 100 μm, and more preferably 35 to 55 μm. If the average particle size is less than the lower limit, the elastic modulus may be improved and the toughness effect may be reduced. If the average particle size exceeds the upper limit, the toughness effect may be reduced due to a decrease in strength.

  The molding material of the present invention contains glass fibers. By containing glass fiber, the mechanical strength of the obtained molded product is improved. Although the fiber diameter of glass fiber is not specifically limited, 10-15 micrometers is preferable. By using glass fibers in the range of the fiber diameter, workability at the stage of forming a molding material can be improved. The fiber length of the glass fiber is not particularly limited, but it is preferable to use a chopped strand type of 1 to 3 mm. By using the glass fiber in the range of the fiber length, workability at the time of forming a molding material, moldability, and strength of the molded body can be improved.

  The glass fiber content is 20 to 55% by weight, more preferably 25 to 50% by weight, based on the entire molding material. If the glass fiber content is less than the lower limit, the mechanical strength of the molded product may be insufficient. If the upper limit is exceeded, workability during the production of the molding material may be reduced. .

The molding material of the present invention contains an inorganic filler other than calcium carbonate and glass fiber. Thereby, the mechanical strength of the obtained molded product can be improved and the dimensional stability can be improved.
Examples of the inorganic filler include, but are not limited to, hydroxides such as aluminum hydroxide and magnesium hydroxide, wollastonite, alumina, silica, clay (unfired clay, calcined clay), barium sulfate, and the like. be able to.
Among these, clay and wollastonite are preferable, and one or more of them can be selected and used. Thereby, the dimensional stability of the molded product can be further improved.

  Although this inorganic filler is not specifically limited, it is preferable to use a thing with an average particle diameter of 30-100 micrometers. Furthermore, 35-55 micrometers is preferable. If the average particle size is less than the lower limit, the effect of improving the mechanical strength and dimensional stability is difficult to appear, whereas if the upper limit is exceeded, the mechanical strength may be lowered, and in the molding material stage Workability may be reduced.

  Although content of inorganic fillers other than glass fiber is not specifically limited, 5 to 30 weight% of the whole molding material is preferable, and also 9 to 25 weight% is preferable. When the content is less than the lower limit, the heat resistance and dimensional stability of the molded product may not be sufficient. When the content exceeds the upper limit, workability during production of the molding material and mechanical strength of the molded product are reduced. There is a case.

  In addition to the components described above, additives such as mold release agents, curing aids, pigments, and elastomers can be added to the phenol resin molding material for a commutator of the present invention as long as the object of the present invention is not impaired. .

   A normal method is employ | adopted as the method of manufacturing the phenol resin molding material of this invention. That is, after adding a phenol resin, a curing agent, an inorganic base material, a release agent, a curing aid, a pigment, etc., and uniformly mixing, a kneading machine alone such as a heating roll, a kneader, a twin screw extruder or other rolls and other It can be obtained by kneading and pulverizing in combination with a mixer.

The following examples further illustrate the present invention.
Tables 1 and 2 show the material compositions and characteristics of Examples and Comparative Examples.

Example 1
25% by weight novolak resin, 5% by weight hexamethylenetetramine, 5% by weight talc, 15% by weight calcium carbonate, 37% by weight glass fiber, 10% by weight clay, pigment, curing aid, release agent 1% by weight of each was added.
The mixed material was melt-kneaded for about 15 minutes with a heating roll at 90 to 100 ° C., cooled and pulverized to obtain a molding material.

Example 2
A molding material was obtained in the same manner as in Example 1 except that the amount of talc was increased to 10% by weight and the amount of calcium carbonate was decreased to 10% by weight.

Example 3
A molding material was obtained in the same manner as in Example 1 except that the amount of talc was increased to 15% by weight and the amount of calcium carbonate was decreased to 5% by weight.

Example 4
Novolak resin increased to 40 wt%, hexamethylenetetramine increased to 7 wt%, talc increased to 7.5 wt%, calcium carbonate decreased to 7.5 wt%, glass fiber decreased to 25 wt% Was the same as in Example 1 to obtain a molding material.

Example 5
A molding material was obtained in the same manner as in Example 1 except that the amount of talc was increased to 15% by weight and the amount of calcium carbonate was decreased to 5% by weight.

Example 6
Novolac resin increased to 40 wt%, hexamethylenetetramine increased to 7 wt%, talc increased to 7.5 wt%, calcium carbonate reduced to 7.5 wt%, glass fiber reduced to 25 wt%, clay A molding material was obtained in the same manner as in Example 1 except that wollastonite was used instead of.

Comparative Example 1
A molding material was obtained in the same manner as in Example 1 except that talc and calcium carbonate were not added, glass fiber was increased to 52% by weight, and clay was increased to 15% by weight.

Comparative Example 2
A molding material was obtained in the same manner as in Example 1 except that calcium carbonate was not added, talc was reduced to 3% by weight, glass fiber was increased to 50% by weight, and clay was increased to 12% by weight.

Comparative Example 3
A molding material was obtained in the same manner as in Example 1 except that talc was increased to 25% by weight, calcium carbonate was not added, glass fiber was reduced to 32% by weight, and clay was increased to 10% by weight.

Comparative Example 4
A molding material was obtained in the same manner as in Example 1 except that talc was not added, calcium carbonate was reduced to 5% by weight, glass fiber was increased to 52% by weight, and clay was increased to 10% by weight.

Comparative Example 5
A molding material was obtained in the same manner as in Example 1 except that talc was not added, calcium carbonate was increased to 25% by weight, glass fiber was decreased to 32% by weight, and clay was increased to 10% by weight.

(Materials used)
Novolac resin: “A-1082” (number average molecular weight 800) manufactured by Sumitomo Bakelite Co., Ltd.
Talc: SP-38 (manufactured by Fuji Talc Industrial Co., Ltd., average particle size 50 μm)
Calcium carbonate: manufactured by Nitto Flour Chemical Co., Ltd., average particle size 50 μm
Glass fiber: CS-3E479FB (manufactured by Nittobo, fiber diameter 11 μm, fiber length 3 mm)
Unfired clay: ECKALITEI (manufactured by Seal Kaolin, average particle size 50 μm)
Wollastonite: manufactured by Kinsei Matec Co., Ltd., average particle size 50 μm
Pigment: Carbon black curing aid: Calcium hydroxide release agent: Calcium stearate

(Preparation of test piece)
The test piece for characteristic evaluation is molded by transfer molding under the following conditions, and the evaluation method is as follows.
Preheating temperature: 95-100 ° C
Mold temperature: 170-175 ° C
Injection pressure: 50 MPa
Curing time: 3 minutes Annealing conditions: 180 ° C., 8 hours (implemented for bending strength test piece)

(Evaluation methods)
Flexural strength, flexural modulus: measured in accordance with JIS K 6911.
Linear expansion coefficient: A bending specimen according to JIS K 6911 was used. The test piece was cut into 4 × 5 × 10 mm height, and the linear expansion coefficient at 40 to 120 ° C. was measured. In addition, anisotropy was calculated by measuring in two directions of the molding material flow direction (parallel direction) and the orthogonal direction during molding.

As is clear from the above results, it can be seen that each example has a balance between strength and elastic modulus and has little anisotropic difference.
Comparative Example 1 does not contain talc, Comparative Example 2 has a large anisotropic difference in linear expansion because the content of talc is small, and Comparative Example 3 has a large amount of talc, so the anisotropic difference in linear expansion is The bending strength of the small one was small.
In Comparative Examples 4 and 5, although the strength and the elastic modulus were satisfactory, the anisotropic difference in linear expansion was increased due to the absence of talc.
From this, it can be seen that the phenol resin molding materials obtained in the examples are suitable for commutators because both the mechanical properties and the dimensional stability are excellent and balanced.

  The phenol resin molding material for a commutator of the present invention has a mechanical property equivalent to or higher than that of a conventional commutator molding material, has a small anisotropic difference in coefficient of linear expansion, and further improves toughness. It can be suitably used to obtain a phenol resin commutator having excellent circularity and excellent press-fitting properties.

Claims (2)

A phenol resin molding material for a commutator, which is 25 to 50% by weight of phenol resin, 5 to 15% by weight of talc, 5 to 15% by weight of calcium carbonate, and 20 to 55% by weight of glass fiber with respect to the entire molding material % And one or more selected from clay or wollastonite in an amount of 5 to 30% by weight. 2. The phenol resin molding material for a commutator according to claim 1, wherein one or more average particle diameters selected from talc, calcium carbonate, and clay or wollastonite are 30 to 100 μm.