JPH04159385A - Friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material capable of being improved in fading resistance while retaining the strength of matrix by mixing a base material, a binder resin, and a friction modifier so as to give pores wherein those having a specified diameter account for a specified percentage. CONSTITUTION:A friction material which contains a base material, a binder resin, and a friction modifier and in which pores having a diameter of 1000Angstrom or smaller account for at least 50vol.% of the total volume of pores. As the base material, organic fibers such as aromatic polyamide fibers, steel fibers, inorganic fibers such as glass fibers, etc., can be used. As the binder resin, thermosetting resins, such as phenolic resin and epoxy resin, can be used. As the friction modifier, graphite, cashew dust, etc., can be used. In addition, this friction material may contain a filler, such as copper powder, silica or barium sulfate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to friction materials. This friction material can be applied to brake pads, clutch fading, etc. of automobiles, industrial vehicles, etc.

[Prior Art] Conventionally, friction materials have been formed by appropriately combining base materials, resins, friction modifiers, and the like. In this friction material, a fade phenomenon occurs in which the coefficient of friction decreases as the temperature of the friction surface increases.

In recent years, in the field of friction materials used in automobiles, there has been a demand for further improvement in fade resistance as automobiles become faster. The applicant has found that the fade resistance is not only affected by the material of the friction material, but also by the pores in the friction material. Therefore, the present applicant proposed a technique for clutch fading in Japanese Patent Application Laid-Open No. 63-6
As disclosed in Publication No. 7435, the pore size is 1 μm.
We developed the following pores that were set to increase the total pore volume by 50%.

In addition, it has been used as a friction material for brakes since 1983.
As disclosed in Japanese Patent No. 151435, a product containing thermally decomposable starch, rice hulls, etc. is disclosed. In this product, starch and rice husks are thermally decomposed during heat treatment during molding, so the pore volume can be increased.

Therefore, the pores can provide an escape route for the gas generated from the resin in the friction material that becomes hot due to frictional heat during use.
It is expected to improve fade resistance.

Further, there have been conventionally known friction materials in which the amount of resin blended into the friction material is reduced in order to reduce the amount of gas generated from the friction material, which has become hot due to frictional heat.

[Problems to be Solved by the Invention] By the way, each of the above friction materials has a large pore diameter, so the strength of the base material of the friction material is not necessarily sufficient, resulting in a decrease in wear resistance, etc. There is a problem that abrasion powder is taken in, which worsens the wear of not only the friction material itself but also the mating material.

Further, even in friction materials in which the amount of resin blended into the friction material is reduced in order to reduce the amount of gas generated, there is a problem in that the strength of the base material of the friction material decreases.

The present invention was developed in view of the above circumstances, and an object of the present invention is to provide a friction material that can improve fade resistance while ensuring base material strength.

[Means for Solving the Problems] In order to solve the above problems, the present inventor has conducted extensive research on pores in friction materials, and has found that, with respect to the total pore volume,
It was discovered that if the proportion of ultra-fine pores with a pore diameter of 1000 angstroms or less is 50% or more by volume, it is possible to improve the fade resistance while ensuring the strength of the base material of the friction material, and completed the present invention. It is something that

The reason why fading resistance can be improved while maintaining the strength of the base material is that in order to adsorb and remove gas generated during friction, it is necessary to
Ultra-fine pores of 00 angstroms or less are sufficient;
Furthermore, pores exceeding 1000 angstroms tend to reduce the strength of the base material of the friction material;
It is presumed that pores larger than angstroms tend to cause noise and vibration due to water adsorption.

Friction 1 of the present invention includes a base material, a binding resin, and a friction modifier, and the ratio of ultrafine pores with a pore diameter of 1000 angstroms or less to the total pore volume is 50% by volume.
% or more.

Known materials can be used as the base material, resin, and friction modifier. For example, base materials include aromatic polyamide fibers, organic fibers such as rayon WjAM, steel fibers, copper I! Metal fibers such as fibers, glass fibers, inorganic fibers such as rock wool, etc. can be used. As the bonding resin, thermosetting resins such as phenol fibers, various modified phenol resins, and epoxy resins can be used.

Graphite, cashew dust, etc. can be used as the friction modifier. The friction material of the present invention can also include fillers. For example, copper powder, silica, barium sulfate, etc. can be used as the filler.

In the friction material of the present invention, the total pore volume is 1000
The ratio of ultra-fine pores having a pore diameter of angstroms or less is set to 50% or more by volume. When setting in this way, for example, friction adjustment materials, fillers,
For example, cashew dust, metal powder, granular graphite, 5
Means for increasing the uniformity of the particle size distribution of 11M barium 1, means for increasing the fluidity of the binding resin when uniformly mixing each material, glass S miscellaneous, rock wool I! It is possible to adopt a means for sufficiently decomposing the fibers such as miscellaneous fibers. Specifically, the particle size of the friction modifier and filler can be, for example, 1 to 50 microns. The pore volume can be measured by the mercury intrusion method, in which mercury is injected in an evacuated state. The mercury intrusion method focuses on the fact that mercury has a contact angle of 90 to 180° with most substances, has the property of not wetting the substance, and will not enter the pores unless it is forcibly injected. be. In the mercury intrusion method, the pressure applied to the mercury is inversely proportional to the pore size through which mercury can penetrate. Further, the fluidity of the bonding resin can be, for example, 60 to 80 mm. Further, in the friction material of the present invention, the ratio of the total pore volume (porosity) to the entire friction material can be 5 to 25%.

[Effects of the Invention] According to the friction material of the present invention, it is possible to maintain a high friction coefficient and a low wear rate, thereby improving fade resistance. Furthermore, according to the friction material of the present invention,
Since the ratio of extremely fine pores having a pore diameter of 1000 angstroms or less to the total pore volume is large, it is possible to suppress a decrease in base material strength and a decrease in wear resistance.

[Example code] Hereinafter, this will be explained in detail using examples.

(Example 1) As shown in Table 1, aromatic polyamide fiber (Kevlar manufactured by DuPont > 10 parts by weight, steel fiber 5 parts by weight,
10 parts by weight of copper fiber N, 10 parts by weight of glass fiber, 10 parts by weight of phenolic resin (PR311 manufactured by Sumitomo Durez Co., Ltd., flow 60 mm) as a binding resin, 8 parts by weight of fine graphite
Parts by weight, cashew dust (FF1085 manufactured by Tohoku Kako Co., Ltd., 100 mesh > 10 parts by weight, 3 parts by weight of copper powder, 3 parts by weight of silica, 31 parts by weight of barium sulfate as an inorganic filler)
Parts by weight. In this case, as shown in Table 2, the phenol resin used had a resin flow of 60 mm, and the cashew dust had a particle size of -100 mesh. In addition, the particle size of copper powder is 20 to 50 μm, and the particle size of silica is 1 to 5 μm.
, the particle size of barium sulfate is 1-5 μm. The mixing conditions were as follows: After the polyamide fibers and glass fibers were defibrated for 30 minutes using an Eirich mixer, other materials were added and uniformly mixed for 15 minutes. Then, this mixture was put into a mold and heated and pressed at a surface pressure of 400 to 9/r:M and a temperature of 170''C for 15 minutes to obtain a molded body.
The friction material of Example 1 was obtained by heat treatment at ℃ for 8 hours, cooling and polishing.

The obtained friction material was measured using a porosimeter ("Poresizer 9310J" manufactured by Shimadzu Corporation, measurement method: mercury intrusion method, pore diameter measurement range: pore distribution of approximately 500 μm to 60 angstroms). The proportion occupied by the pore volume was measured.Furthermore, the proportion occupied by ultra-fine pores with a pore diameter of 1000 angstroms or less with respect to the total pore volume was measured using the above-mentioned porosimeter.In addition, when measuring with the porosimeter, the cell equipped with the sample was used. was evacuated, and mercury was injected under pressure.

The measurement results are shown in Table 1, and the ratio of the total pore volume to the entire friction material was 15%. Furthermore, the ratio of ultra-fine pores with a pore diameter of 1000 angstroms or less to the total pore volume was 62%.

Furthermore, using a brake dynamo tester, the obtained friction materials shown in Tables 1 and 2 were subjected to a fade resistance test, and the minimum friction coefficient and wear rate were measured. The test conditions for measuring the friction coefficient are JASO-C406-82 (Brake model: PD
51S, rotor thickness: 18mm, inertia v: 4.
OK5F-m-s2). The test conditions for measuring the wear rate were in accordance with JASo-C427-83 (brake model: PD51S, rotor thickness: 1 Bmm, inertia v: 3.5Kfl·m-52).

As shown in Table 1, the test results show that the minimum friction coefficient is 0.2.
4, the wear rate at 100°C is 1°1, and 2
The wear rate at 00°C was 2.3.

(Example 2) The friction material according to Example 2 was basically manufactured under the same conditions as in Example 1. However, steel fiber has been abolished and copper m
The amount of miscellaneous substances was increased to 15 parts by weight.

In Example 2, as shown in Table 1, the pore volume accounted for 12% of the total friction material. Further, the ratio of ultra-fine pores with a pore diameter of 1000 angstroms or less to the total pore volume was 58%.

The friction material of Example 2 was also subjected to a fade resistance test in the same manner as in Example 1. The test results are shown in Table 1, and the minimum friction coefficient is 0°22, and at 100°C
The wear rate at 200° C. was 1.2, and the wear rate at 200° C. was 2.2.

(Comparative Example 1) A friction material according to Comparative Example 1 was basically manufactured under the same conditions as in Example 1. However, the following points are different.

That is, as shown in Table 2, the resin flow of the phenol resin was 2Qmm, and the cashew dust used was +100 mesh. As for the mixing conditions, all the materials were uniformly mixed for 15 minutes using an Eirich mixer.

In Comparative Example 1, as shown in Table 1, the pore volume accounted for 18% of the total friction material. Furthermore, the ratio of ultra-fine pores with a pore diameter of 1000 angstroms or less to the total pore volume was 42%.

Then, a performance test was conducted in the same manner as in Example 1. As shown in Table 1, the test results show that the minimum friction coefficient is 0°21.
The wear rate at 100°C was 1.9, and the wear rate at 200°C was 3.4.

(Comparative Example 2) A friction material according to Comparative Example 2 was basically manufactured under the same conditions as in Example 2. However, the following points are different.

That is, as shown in Table 2, the resin flow of the phenol resin was 20 mm, and the cashew dust used was +100 mesh. As for the mixing conditions, all the materials were uniformly mixed for 15 minutes using an Eirich mixer.

In Comparative Example 2, as shown in Table 1, the pore volume accounted for 15% of the total friction material. Furthermore, the ratio of ultra-fine pores with a pore diameter of 1000 angstroms or less to the total pore volume was 39%.

Then, a performance test was conducted in the same manner as in Example 1. As shown in Table 1, the test results show that the minimum friction coefficient is 0°18.
The wear rate at 100'C is 2.1, and at 200'C
The wear rate per year was 3.8.

(Evaluation) As explained above, in Examples 1 and 2, the ratio of ultra-small pores with a pore diameter of 1000 angstroms or less to the total pore volume is set to 50% or more in volume %. . It can be seen that Examples 1 and 2 exhibit higher friction coefficients than the Comparative Examples, have lower wear rates than the Comparative Examples, and have excellent fade resistance.

Patent applicant: Aisin Kako Co., Ltd.

Claims (1)

[Claims] (1) It contains a base material, a binding resin, and a friction modifier, and is characterized in that the ratio of ultrafine pores with a pore diameter of 1000 angstroms or less to the total pore volume is 50% or more by volume. friction material.