JP2000178538A - Friction material composition and friction material made by using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material composition which can prevent or reduce the vibration and noise of a brake and gives a disc rotor suffering less wear by incorporating a specified amount of triiron tetraoxide therein. SOLUTION: This friction material composition contains 0.5-23 wt.% triiron tetraoxide, 10-45 wt.% fibrous material, and 20-60 wt.% filler other than triiron tetraoxide, and if necessary, 1-8 wt.% metal powder. The triiron tetraoxide used preferably comprises one having a mean particle diameter of 0.4 μm or smaller with a polyhedron or needle shape. In addition to the triiron tetraoxide, a fibrous material comprising e.g. copper fibers, aramid fibers, or calcium silicate whisker, a binder comprising e.g. a thermosetting material or a rubber composition, a friction modifier comprising e.g. molybdenum disulfide or graphite, and a filler comprising e.g. barium sulfate are used for the friction material. A disc brake pad is obtained by preforming the composition into a prescribed shape, press molding it in a die at 130-180 deg.C, heat treating the molding, and baking the surface at high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material composition suitable for a friction material such as a disc brake pad and a brake lining used for braking automobiles, railway vehicles, various industrial machines and the like, and a friction material composition. Related to friction material.

[0002]

2. Description of the Related Art Friction materials such as disc brake pads and brake linings are used in automobiles, railway vehicles, various industrial machines and the like for braking. Friction materials such as disc brake pads and brake linings currently used are braked by using a fibrous substance such as aramid fiber or ceramic fiber, a friction modifier or the like as shown in JP-A-6-184525. Non-Asbestos-Organic (hereinafter referred to as NAO) -based friction materials that generate less squeal and noise are mainly used.

However, performance requirements for brakes in recent years have tended to become more and more advanced. In contrast to conventional NAO materials, while maintaining sound vibration characteristics such as brake squeal and abnormal noise at the time of braking, effective characteristics and high speed Improvements in braking characteristics during running are required, but conventional friction materials such as those described above, for example, disc brake pads, have insufficient sound and vibration characteristics, resulting in reduced effectiveness and braking characteristics at high speed running. Tend to.

[0004]

According to the first, second and third aspects of the present invention, it is possible to prevent or reduce brake vibration during braking at high speed (hereinafter referred to as "high speed / high temperature judder") and prevent brake squeal. Another object of the present invention is to provide a friction material composition which can be reduced and is suitable for a friction material having a small wear amount of a disk rotor. The fourth aspect of the present invention is to provide a friction material capable of preventing or reducing high-speed / high-temperature judder, preventing or reducing brake squeal, and having a small wear amount of the disk rotor.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a friction material composition containing 0.5 to 23% by weight of ferric oxide in the total composition. The present invention also relates to a friction material composition in which ferric oxide has an average particle size of 0.4 μm or less. Also,
TECHNICAL FIELD The present invention relates to a friction material composition in which triiron tetroxide is iron tetroxide containing one or both of a polyhedral shape and a needle shape. Furthermore, the present invention relates to a friction material obtained by subjecting the above-mentioned friction material composition to heat and pressure molding.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, iron tetroxide must be contained in the entire composition in an amount of 0.5 to 23% by weight, preferably 1 to 20% by weight, more preferably 3 to 18% by weight. If it is less than 0.5% by weight, the effect of preventing or reducing high-speed and high-temperature judder is reduced, and if it exceeds 23% by weight, squealing occurs and the disk rotor wear increases.

The ferric oxide has a polyhedral shape such as a hexahedral shape and an octahedral shape, a needle shape, a spherical shape and an irregular shape. In the present invention, the stability of the friction coefficient and the friction coefficient are improved. From the viewpoint, it is preferable to use polyhedral and acicular iron tetroxides, and these can be used alone or in combination. The average particle size of triiron tetroxide is preferably 0.4 μm or less, more preferably 0.3 μm or less, and 0.2 to
The range of 0.1 μm is more preferable. If the thickness exceeds 0.4 μm, squealing tends to occur and the amount of wear of the disk rotor tends to increase.

As the material of the friction member, a generally known material is used. In addition to the above-mentioned triiron tetroxide, for example, copper fiber, brass fiber, acrylic fiber, aramid fiber, ceramic fiber,
Rock wool, carbon fiber, fibrous substances such as calcium silicate whisker, calcium carbonate whisker, potassium titanate whisker, magnesium carbonate whisker, phenolic resin, epoxy resin, melamine resin, thermosetting resin such as polyimide resin and NBR, SBR, Binders including rubber compositions such as IR, friction modifiers such as cashew dust, antimony trisulfide, molybdenum disulfide, graphite, fillers such as barium sulfate, calcium carbonate, magnesium carbonate and the like. Metal powder such as bronze, tin, and zinc is added.

The content of the fibrous substance in the above composition is preferably from 10 to 45% by weight in the whole composition,
More preferably, the content is 5 to 40% by weight.
More preferably, the content is 5% by weight. The content of the binder is preferably 5 to 15% by weight, more preferably 6 to 13% by weight, and more preferably 7 to 13% by weight in the whole composition.
More preferably, the content is about 11% by weight. The content of the friction modifier is preferably 4 to 25% by weight, more preferably 7 to 22% by weight, even more preferably 10 to 19% by weight in the whole composition.

The content of the filler excluding triiron tetroxide is preferably 20 to 60% by weight in the whole composition.
More preferably, the content is 25 to 50% by weight, and 30 to 50% by weight.
More preferably, the content is 40% by weight. Further, the content of the metal powder to be added as needed is 1 to
The content is preferably 8% by weight, more preferably 2 to 7% by weight, even more preferably 3 to 6% by weight. These components are blended so that the total composition becomes 100% by weight.

[0011] The disc brake pad according to the present invention comprises:
The friction material composition is preformed into a predetermined shape, and then the back metal and the preformed body are inserted into a mold, and then molded by a heat and pressure molding method, followed by a heat treatment. If necessary, the surface of the molded body may be further baked at a high temperature of 400 to 800 ° C. after the heat treatment. The heating temperature during molding is preferably from 130 to 180 ° C, more preferably from 140 to 170 ° C. The pressure is preferably 30 to 70 MPa, and 45
~ 55 MPa is more preferred. Heat treatment temperature is 100 ~
300 ° C is preferable, and 150 to 250 ° C is more preferable.

[0012]

Embodiments of the present invention will be described below. Examples 1 to 4 and Comparative Examples 1 and 2 The components shown in Table 1 were blended and uniformly mixed with a mixer to obtain a friction material composition. Next, after preforming the friction material composition into a predetermined shape, a backing metal and a preformed body are inserted into a mold,
It was heated and pressed at 140 ° C. ± 5 ° C. and 50 MPa for 10 minutes, further heated at 250 ° C. for 5 hours, cooled and polished to obtain a disc brake pad.

[0013]

[Table 1]

Next, a disc brake pad according to an embodiment of the present invention and a disc brake pad according to a comparative example will be described.
Comparative tests of high-speed and high-temperature judder (torque fluctuation), brake squeal and disk rotor wear were conducted. Table 2 shows the results. The test conditions are as follows.

Using a high-speed and high-temperature judder dynamometer, a brake test was performed under the following braking conditions, and the torque fluctuation at the time of regulation was measured. Braking conditions: vehicle speed before braking: 200 km / h, rotor temperature before braking: two conditions of 200 ° C. and 300 ° C., braking deceleration: 0.
3G constant The brake model used was Nissan Motor Co., Ltd., model name: Primera (P11). Brake squeal An actual vehicle test was performed using Nissan Motor Co., Ltd., model name: Primera (P11) according to JASO C 402-79, squeal during the test was measured, and the occurrence rate of squeal of 75 dB or more was determined. Abrasion amount The same actual vehicle test as described above was performed, and the abrasion amount was measured from the difference in thickness of the disk rotor before and after the test, and the abrasion resistance was compared.

[0016]

[Table 2]

As shown in Table 2, it can be seen that the disk brake pad according to the embodiment of the present invention has a low torque fluctuation, that is, a high-speed / high-temperature judder, and has a low brake squealing rate and a small disk rotor wear amount. On the other hand, the disc brake pad of Comparative Example 1 has a high-speed / high-temperature judder, and the disc brake pad of Comparative Example 2 has a high-speed / high-temperature judder, a high brake squealing rate and a large disc rotor wear amount. .

[0018]

According to the first, second and third aspects of the present invention, a friction material suitable for a friction material capable of preventing or reducing high-speed / high-temperature judder, preventing or reducing brake squeal, and having a small wear amount of a disk rotor. A composition can be provided. According to the fourth aspect of the present invention, it is possible to provide a friction material that can prevent or reduce high-speed / high-temperature judder, prevent or reduce brake squeal, and reduce the amount of wear of the disk rotor.

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Claims (4)

[Claims] 1. A composition comprising 0.5 to 23 iron trioxide in the total composition.
A friction material composition containing about 100% by weight. 2. The friction material composition according to claim 1, wherein the average particle size of the triiron tetroxide is 0.4 μm or less. 3. The friction material composition according to claim 1, wherein the triiron tetroxide is triiron tetroxide containing one or both of a polyhedral form and a needle form. 4. A friction material formed by heating and pressing the friction material composition according to claim 1, 2 or 3.