JP3392255B2 - Brake friction material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used for a brake, and more particularly to a non-asbestos type brake friction material suitable for a brake pad of an automobile or the like.

[0002]

Brake friction materials used for automobile brake pads are prepared by mixing a fiber material with a lubricant, a filler, a friction modifier, a pH adjuster, and the like, and a binder with these components. It is prepared by sufficiently stirring and mixing, and then performing compression molding while heating. Among them, for example, those used under high load or high frequency, such as a small truck or a taxi, are conventionally used to ensure wear resistance.
It contains 25 to 35% by volume of steel fiber as a fibrous material, 30 to 35% by volume of graphite as a lubricant, 5 to 15% by volume of barium sulfate as a filler, and 20 to 30% by volume of a phenol resin as a binder. Contains.

On the other hand, in passenger cars, in order to prevent the generation of abnormal noise, conventionally, 5 to 10% by volume of metal fibers such as steel fibers and copper-copper fibers, and inorganic fibers such as ceramic fibers and rock wool are used as fiber materials. In addition to containing 10 to 20% by volume and 1 to 10% by volume of aramid fiber, 5 to 5% graphite as a lubricant.
10% by volume, 1 to 10% by volume of sulfides such as antimony trisulfide and molybdenum disulfide, and 20 to 30% by volume of a phenol resin as a binder.

[0004]

However, among the above-mentioned conventional brake friction materials, those for trucks and taxis have a large content of steel fiber and have a static friction coefficient (μ).
Since the difference between the friction coefficient and the dynamic friction coefficient is large, an abnormal noise such as a goo noise may be generated when the brake is operated. Further, since the brake is highly aggressive to the disc rotor, the thickness of the disc rotor may change with use, which may cause vibration or judder.

On the other hand, in the case of brake friction materials for passenger cars,
Ceramic fibers, rock wool, etc. are mixed in the fiber material, but these fibers are thin with a diameter of 3 to 5 μm, and antimony trisulfide and molybdenum disulfide used as lubricants are oxidized at around 250 ° C. to degrade. Therefore, when the brake friction material becomes hot due to high load braking operation or high frequency brake operation, the fiber material may come off and the lubricity may deteriorate, resulting in a decrease in the mechanical strength of the brake friction material. There was a problem that the amount of wear increased.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in a brake friction material in which a lubricant is mixed with a fiber material, in particular, the fiber material has a diameter of 2
10 μm or more of fibers having a size of 0 μm or more per the above brake friction material
20 to 30% by volume, and the lubricant has a heat resistance of 300 ° C. or higher for each of the brake friction materials of 20.
It is characterized by containing -40 volume%.

Here, as the fiber material, metal fibers such as steel fibers and copper-copper fibers, and / or potassium titanate fibers are used. Particularly, when only metal fibers are used as the fiber material, the content thereof is 10 to 20% by volume based on the brake friction material.

[0008]

In the brake friction material according to the present invention, the fiber material having a diameter of 20 μm or more is adopted as the main element of the fiber material instead of the fiber material having a small diameter, such as ceramic fiber or rock wool, so that the fiber material does not easily come off. Become. Further, since the lubricant has a heat resistance of 300 ° C. or higher, the deterioration of the lubricity due to the temperature rise can be small.

[0009]

EXAMPLES Examples of the present invention will be described below. As the fiber material, metal fibers (steel fibers and / or copper fibers) and potassium titanate fibers each having a diameter of 20 μm or more, and ceramic fibers and potassium titanate (whisker) having a diameter of less than 20 μm are prepared. did. Further, graphite, mica and molybdenum disulfide were used as lubricants, phenol resin was used as a binder, and barium sulfate was used as a filler.

The above materials were blended in the proportions (volume%) as shown in the columns of Examples 1 to 8 in Table 1, thoroughly mixed and stirred using a Rödege mixer, and then dried, and a predetermined mold was formed at room temperature. It was preformed. The preformed product was further heat-compressed and molded using a predetermined mold, and then heat-treated at 200 ° C. for 5 hours to prepare brake friction materials (Examples 1 to 8).

Each of these brake friction materials contains 10 to 20% of metal fibers having a diameter of 20 μm or more as a fibrous material, and / or a total of 10 potassium titanate fibers.
It is contained so as to be 30%. Also, it contains 20 to 40% of graphite and mica as a lubricant.

On the other hand, in order to make a comparison with the above-mentioned examples, the above materials were blended in proportions (volume%) as shown in the columns of Comparative Examples 1 to 7 in Table 1, respectively, and brake friction was carried out in the same manner as in the above-mentioned examples. Materials (Comparative Examples 1 to 7) were produced. Here, Comparative Example 1 has a relatively low content of fiber material having a diameter of 20 μm or more, and Comparative Example 2 has a relatively high content of metal fiber having a diameter of 20 μm or more. Examples 3, 4
Is a thin fiber material with a diameter of less than 20 μm,
Comparative Example 5 has a relatively low content of the lubricant, and Comparative Example 6 has a relatively high content of the lubricant.
In Comparative Example 7, molybdenum disulfide having low heat resistance is used as the lubricant.

[0013] (Note): Phenolic resin, barium sulfate, etc.

Then, the wear resistance of each brake friction material produced as described above is determined according to "Japan Society of Automotive Engineers Standard J
According to "ASOC-427", each test was conducted in a temperature range of 100 to 400 ° C, and a general running test was conducted using an actual vehicle equipped with each brake friction material to test for abnormal noise generation during brake operation.
The results of these tests are shown in Table 2.

[0015] *: Insufficient μ, all temperatures in Table 2 are Celsius.

As a result of the test, in Examples 1 to 7, the wear amount of the brake friction material at each temperature was 0.10 mm.
Stable and less than the following, high wear resistance was maintained. In addition, in a test using an actual vehicle, it was confirmed that no abnormal noise was generated during brake operation.

On the other hand, in Comparative Examples 1 and 3, the amount of wear of the brake friction material increased as the temperature increased, and in a test using an actual vehicle, abnormal noise such as judder and goo noise was generated during brake operation. . Further, in Comparative Example 2, although the abrasion of the brake friction material was small as in the case of Example, an abnormal noise was generated during the brake operation, and in Comparative Examples 4, 5 and 6, no abnormal noise was generated during the brake operation, but the temperature was decreased. It was observed that the amount of wear of the brake friction material increased with the increase.

[0018]

As described above, according to the present invention, it is possible to prevent both the dropping of the fibrous material in the brake friction material and the thermal deterioration of the lubricant, and thus (1) Improvement of wear resistance at high temperature. (2) Since the content of the steel fiber can be reduced, it is possible to obtain an excellent effect that it is possible to prevent the generation of abnormal noise such as judder and goo noise during brake operation.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-9462 (JP, A) JP-A-59-54644 (JP, A) JP-A-4-88227 (JP, A) JP-A-6- 93110 (JP, A) JP-A-6-49439 (JP, A) JP-A-4-106183 (JP, A) JP-A-63-266231 (JP, A) JP-A-6-129456 (JP, A) JP-A-6-129454 (JP, A) JP-A-5-9460 (JP, A) JP-A-1-203728 (JP, A) JP-A-3-181628 (JP, A) JP-A-4-318093 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16D 69/02

Claims (5)

(57) [Claims] 1. A brake friction material comprising a fibrous material mixed with a lubricant or the like, wherein the fibrous material contains metal fibers having a diameter of 20 μm or more in an amount of 10 to 20% by volume per the braking friction material. A brake friction material, wherein the lubricant contains a substance having a heat resistance of 300 ° C. or higher in an amount of 20 to 40% by volume based on the brake friction material. 2. A brake friction material prepared by mixing a fibrous material with a lubricant or the like, wherein the fibrous material has a total of 10 metal fibers and potassium titanate fibers each having a diameter of 20 μm or more. Brake friction material, characterized in that the content thereof is ˜30% by volume, and the lubricant contains a substance having a heat resistance of 300 ° C. or higher in an amount of 20 to 40% by volume per the brake friction material. 3. The metal fibers are steel fibers and / or
Or it is copper fiber, The claim 1 or 2 characterized by the above-mentioned.
Brake friction material described. 4. A brake friction material comprising a fibrous material mixed with a lubricant or the like, wherein the fibrous material is potassium titanate fiber having a diameter of 20 μm or more in an amount of 10 to 30% by volume per the brake friction material.
20-40% by volume of the above-mentioned lubricant containing a substance having a heat resistance of 300 ° C. or more per brake friction material
Brake friction material characterized by containing. 5. The brake friction material according to claim 1, 2, 3 or 4, wherein the substance is graphite and / or mica.