JPH0774657B2 - Friction material for brake - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel brake friction material used for vehicles such as automobiles and railways, brake pads for industrial machines and brake shoes.

[Prior Art] Conventionally, asbestos has been widely used as a main fiber base material of this type of friction material for brakes, but carcinogenicity of asbestos has been taken up as a serious problem, and asbestos regulations are being established in various countries. There have been many studies on brake friction materials that do not contain asbestos.

For example, a friction material in which heat-resistant organic fibers such as glass fibers and aromatic polyamide fibers are bonded with a thermosetting resin (Japanese Patent Laid-Open No. 57-85).
No. 877) or a non-melting heat resistant organic fiber and calcium metasilicate fiber carbonized at around 500 ° C. together with a friction performance modifier with a thermosetting binder (JP-A-58-13684). )It is shown.

However, since the glass fibers and calcium metasilicate fibers used in these friction materials have a smaller kalami of fibers than asbestos, there is a problem such as an increase in the amount of wear at high temperatures, the present inventors, In order to solve these problems, a brake friction material comprising metal fibers, heat-resistant organic fibers, calcium metasilicate fibers having an aspect ratio of 30 to 40, a thermosetting resin, and a friction modifier was invented (Japanese Patent Application No. 62-099565).

[Problems to be Solved by the Invention] However, metal fibers such as steel fibers used in a friction material for a brake disclosed in Japanese Patent Application No. 62-099565 are not compatible with a disc rotor or a drum which is a mating material. At the contact surface, the mating material is attacked to wear the disc rotor. This wear causes a problem that the life of the disk rotor is shortened.

[Means for Solving Problems] The present invention solves the above problems, and provides a friction material for a brake which is excellent in wear resistance and fade resistance not only at room temperature but also at high temperature and which is not aggressive to the mating material. It is provided.

That is, the present invention is a micro Vickers hardness 70HV ~ 150H
A friction material for a brake, which comprises a fiber base material composed of a non-ferrous metal fiber V, a heat-resistant organic fiber, and a calcium metasilicate fiber having an aspect ratio of 30 to 40, a thermosetting resin, and a friction modifier.

The non-ferrous metal fiber having a micro Vickers hardness of 70 HV to 150 HV used in the present invention is preferably one or a mixture of copper fiber and brass fiber. These non-ferrous metal fibers are preferably fibers produced by cutting and have an average diameter of 10 to 300 μm, preferably 20 to 60 μm. The fiber length is 0.1 to 10 mm, preferably 1 to 3 mm. The content of the non-ferrous metal fiber is 5 to 60% by weight based on the total amount of friction material.

The heat-resistant organic fiber of the present invention is an aromatic polyamide fiber,
Novoloid fibers and wholly aromatic polyester fibers are preferable, and fibrillated aromatic polyamide fibers are particularly preferable.

The calcium metasilicate fibers having an aspect ratio of 30 to 40 of the present invention have high heat resistance (melting point 1540 ° C.), and among those generally called wollastonite, those having a β-type crystal structure. , The shape of which is needle-like or oblong, and the aspect ratio is 30 to 40. The present invention is a fiber such as steel fiber, potassium titanate fiber, carbon fiber, etc. It is not limited to mix.

The thermosetting resin used in the present invention is one or a mixture of a phenol resin, a melamine resin and a phenol resin modified with oil, melamine, epoxy, polyvinyl butyral, an epoxy resin, a polyester resin.

The friction modifier of the present invention includes graphite, silica powder, alumina powder, barium sulfate, cashew dust, diatomaceous earth, calcium carbonate and the like.

The method for manufacturing the friction material for a brake of the present invention is a method that has been conventionally performed and is as follows.

The predetermined amounts of the fiber base material, the thermosetting resin and the friction modifier are uniformly mixed with a Henschel mixer, a Banbury mixer, a kneader or a V-type blender. Next, the mixed material is filled in a mold and pressed to perform preforming.

This preform is heated and pressed to harden and bond the thermosetting resin, and then further heat-treated to obtain a friction material for a brake.

[Operation] The friction material for a brake of the present invention has a micro Vickers hardness.
70-150 HV non-ferrous metal fibers, heat-resistant organic fibers and acicular or long columnar calcium metasilicate fibers with an aspect ratio of 30-40 are used as the fiber base material. Even if the friction material is exposed to high temperature and the thermosetting resin is carbonized and decomposed to lower the binding force, the fibrous base material is less likely to fall off and wear resistance is good.

Further, since the mating material is less aggressive and the mating material does not wear, the wear resistance is further improved.

Also, since acicular or long pillar-shaped calcium metasilicate fibers with an aspect ratio of 30 to 40 are used, many minute pores can be formed on the friction surface, and thermosetting resin and heat resistant organic fibers are thermally decomposed by high temperature friction. Since the generated gas is immediately absorbed and diffused, the coefficient of friction is not lowered and the fade resistance is improved.

[Examples] Examples of the present invention will be shown below, but the present invention is not limited thereto.

Examples 1 to 5 and Comparative Examples 1 to 3 A V type blender was used to uniformly mix the compositions shown in Table 1 to obtain mixed materials. The surface pressure of this mixed material is 300kg / cm at room temperature.
Pre-molding was performed for 20 seconds with a molding machine adjusted to ² to obtain a pre-molded product. Then, the surface pressure was 300 kg / cm ² and the mixture was heated and pressed for 7 minutes using a molding machine whose mold temperature was adjusted to 150 ° C.

Then, it was heat-treated in a heating furnace at 250 ° C. for 3 hours, allowed to cool, and then ground to a predetermined size to obtain a friction material for a brake pad.

A friction material and a fade resistance test were conducted on a friction material obtained by the formulation of each example in Table 1 with a brake dynamometer tester.

JASO-C427-83 for abrasion resistance test, JA for fade resistance test
Performed according to SO-C406-82.

[Effects of the Invention] As is clear from Table 2, the friction material of the present invention has a smaller wear rate of the friction material and better durability than the conventional friction material. It can be seen that the amount of wear is small and the aggression is small. Regarding the fade resistance, the minimum friction coefficient during the next one braking after repeating the number of braking 10 times is high,
Good fade resistance.

As described above, the friction material obtained by the present invention is a friction material for brakes which is not only wear-resistant and fade-resistant but also has little attacking property of the mating material.

Claims (2)

[Claims] 1. A fiber base material comprising a cut non-ferrous metal fiber having a micro Vickers hardness of 70 HV to 150 HV, a heat resistant organic fiber, and a calcium metasilicate fiber having an aspect ratio of 30 to 40, a thermosetting resin, and a friction modifier. A friction material for brakes, which is made of 2. The friction material for a brake according to claim 1, wherein the non-ferrous metal fiber is at least one kind of copper fiber and brass fiber.