JPS61258886A - Friction material composition - Google Patents

Abstract

PURPOSE:To provide a composition containing a specific amount of tung oil or linseed oil, capable of reducing the variation of frictional coefficient and preventing the generation of abnormal low-frequency noise and vibration of an automobile body and useful for a frictional material of disk brake pad, brake lining, etc., of an automobile. CONSTITUTION:The objective composition can be produced e.g. by adding 0.5-10vol% tung oil and/or linseed oil to a composition containing steel fiber, graphite, barium sulfate, phenolic resin and iron powder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a friction material composition for disc brake pads, brake linings, etc. used for braking automobiles and the like.

(Prior Art and its Problems) For example, disc brakes are used as braking devices for automobiles, etc., but conventional disc brakes generate an unpleasant noise called brake squeal when braking.

In recent years, the brake squeal phenomenon that occurs during braking has become a serious problem, particularly in the general market, and various efforts have been made to investigate its causes and take countermeasures.

This brake squeal phenomenon is a high-frequency sound with a frequency of 2,000 to 1,000 Hz or more, but there is also a low frequency sound of about 100 to 300 Hz that occurs when automatic cars start and stop. There is an abnormal frequency noise.

This low-frequency noise is caused by instantaneous fluctuations in the coefficient of friction between the mating material and the friction material at extremely low speeds.

At times, the vibrations are so large that they cause the vehicle to vibrate.

Recently, it has been known that this low-frequency noise occurs very significantly in semi-metallic disc brake pads that use steel fiber as an asbestos substitute fiber.

For this reason, with the future growth in automatic cars and the trend toward non-asbestos (semi-metallic), this is becoming a major problem that needs to be solved, similar to general high-frequency noise.

The low-frequency noise mentioned above is caused by fluctuations in the coefficient of friction between the mating material and the friction material, specifically the disc brake pad, at extremely low speeds (below 5 km/hour), and this occurs through the mating material disc and caliber. It resonates with the undercarriage of the car and produces abnormal noise, so an effective way to prevent this is to improve the rigidity of the undercarriage. It is important to modify the material to suppress fluctuations in the coefficient of friction and reduce noise.

The present inventors investigated the variation in the coefficient of friction (stick-slip) from 0.5) on/hour to stop. As a result 2, it was found that the friction coefficient of a normal semi-metallic disc brake pad becomes large just before stopping. The increased coefficient of friction causes stick-slip with the disc rotor, which is the mating material, and causes low-frequency noise and vehicle body vibration. In contrast, it was found that conventional asbestos-based disc brake pads, which produce less abnormal noise, have a smaller fluctuation range and are more likely to attenuate.

(Objective of the Invention) In view of the above circumstances, an object of the present invention is to provide a friction material composition for preventing or reducing low-frequency noise and vehicle body vibration.

(Means for Solving the Problems) As a result of various studies in order to eliminate the above-mentioned drawbacks, the present inventors found that tung oil and/or linseed oil was added to the entire friction material composition.
．． Disc brake pads, brake linings, etc. that do not have an abnormally large coefficient of friction when containing 5 to 10 volumes of CH, and prevent or reduce low-frequency abnormal noise and vehicle body vibration even in actual automobile tests. It has been discovered that a friction material composition that provides a friction material of

The present invention contains 0.5 tung oil and/or linseed oil in the entire composition.
The present invention relates to a friction material composition containing ~10 volumes.

In the present invention, it is necessary to contain 0.5 to 10 volumes of tung oil and/or linseed oil in the entire composition.
．． If the capacity is less than 5, the objective of the present invention cannot be achieved because the coefficient of friction becomes abnormally large and the effect of reducing low-frequency abnormal noise is small, causing vibration of the vehicle body. Moreover, if the capacity exceeds 10, there will be a drawback that the coefficient of friction at high temperatures will decrease.

In addition to the above-mentioned tung oil and/or linseed oil, the friction material composition of the present invention also includes steel fiber, asbestos modified with melamine,
It contains a binder resin such as a phenolic resin modified with epoxy, a lubricant such as graphite, molybdenum disulfide, etc., and an organic friction modifier, barium sulfate, metal powder other than the above, etc. are added as necessary.

(Example) The present invention will be explained below with reference to Examples.

Example 1 The ingredients shown in Table 1 were blended, mixed uniformly using a mixer, dried at 82.5±2.5°C for 2 hours in an electric oven, and then crushed to form a molded powder. forming, then 152.5±2.5℃, pressure 500k
Hot pressure molded for 5 minutes under g/cm2 conditions.

Thereafter, it was baked at 200° C. for 5 hours to obtain a semi-metallic disc brake pad.

Table 1 Example 2 The components shown in Table 2 were blended and the same steps as in Example 1 were carried out to obtain a semi-metallic disc brake pad.

Note that the same raw materials as in Example 1 were used.
Table 2 (margin) Example 3 The components shown in Table 3 were blended and the same steps as in Example 1 were carried out to obtain a semi-metallic disc brake pad.

The linseed oil used was non-break linseed oil manufactured by Nisshin Seimitsu Oil Co., Ltd., and the other raw materials used were the same as in Example 1.

Comparative Example 1 A semi-metallic disc brake pad was obtained by blending the components shown in Table 4 without containing tung oil and/or linseed oil, and following the same steps as in Example 1. Note that the same raw materials as in Example 1 were used as shown in Table 4.

Table 4 Next, a semi-metallic disc brake pad using the friction material composition of the present invention and a conventional semi-metallic disc brake pad (comparative example 1) were installed on an actual car.
A comparative test was conducted on the generation of low-frequency noise at speeds of , sb/hour or less. The results are shown in Table 5.

Table 5 Test conditions Abnormal noise level 5 levels A, B, C, D, E Elementary school - 111 year old large test car: (1800cc automatic car, temperature is semi-metallic disc brake pad temperature, semi-metallic disc brake pad temperature Area 38an", total vehicle weight 1320kL, brake type, collet type]
As can be seen from Table 5, the semi-metallic disc brake pad using the friction material composition of the present invention produces less abnormal noise. In contrast, it can be seen that the conventional semi-metallic disc pad makes a lot of noise.

Although the present invention has been described in detail in the case where it is applied to a semi-metallic disc brake pad, similar effects can be obtained with other friction materials such as disc brake pads and brake linings.

(Effects of the Invention) According to the present invention, a disc brake pad is provided in which fluctuations in the coefficient of friction are reduced, and low-frequency noise and vehicle body vibration are not generated at all or are extremely small.

A friction material composition that provides brake linings and the like is obtained.

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Claims (1)

[Claims] 1. 0.5 to 1 tung oil and/or linseed oil in the entire composition
A friction material composition containing 0% by volume.