JPH02209635A - Friction material for brake - Google Patents

Abstract

PURPOSE:To prevent lowering of frictional coefficient at the time of high temperature braking by having a friction material for brake made of a fiber base material containing at least metal fiber, a filling material and thermosetting resin contain black lead whose crystal grain (La, Lc) is specific. CONSTITUTION:A mixed material for a fiction material for brake is obtained by a fiber base material made of inorganic fiber such as glass fiber, silica fiber and alumina fiber containing at least metal fiber such as steel fiber and so on and organic fiber, a filling material such as cashoo dust, rubber dust, barium sulfate and so on, and thermosetting resin. Moreover, it is made to contain 5 to 20weight% of black lead grain whose crystal grain (La, Lc) is 80 to 90nm, heated by a forming machine and pressurized to grain the friction material for brake. In this way, abrasion resistance is improved and exfoliation strength between crystal grains is increased, which restrains adhesion of black lead to the other material and can prevent lowering of friction coefficient at the time of high temperature braking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a friction material for brakes mainly used in automobiles, railway vehicles, airplanes, industrial machinery, etc.

[Conventional technology] Conventionally, this type of friction material has mainly used asbestos as the fiber base material, but recently, asbestos-free friction materials have been promoted to improve the working environment and prevent asbestos pollution. .

As fiber base materials to replace asbestos, inorganic fibers such as glass fiber, alumina fiber, rock wool, potassium titanate fiber, metal fibers such as steel fiber, copper 111I fiber, brass fiber, hemp, cotton, rayon, phenol fiber, and aromatic fibers are used. Fiber base materials made of organic fibers such as polyamide ya fibers alone or in appropriate combinations are being considered.

For example, a friction composition using a mixture of steel fiber and graphite or graphite and rubber is disclosed in JP-A-61-168684. Also, JP-A-62-106980
The publication discloses a friction material comprising metal fibers (metal powder), aramid fibers (aramid valves), a lubricant such as graphite or molybdenum disulfide, a binder, and a filler.

[Problems to be Solved by the Invention] However, in this type of friction material whose main components are metal fibers such as steel fibers and graphite, graphite, which is used as a wear resistance improver of the friction material, becomes resistant to friction during high-temperature braking. There is a problem in that it adheres to the disc rotor, which is a material, and reduces the coefficient of friction.

[Means for Solving the Problems] An object of the present invention is to solve the above problems and provide a high coefficient of friction,
The present invention provides a brake friction material with excellent wear resistance.

The present inventors have continued their intensive research in order to solve the above problems. As a result, it was discovered that the degree of crystallinity of graphite greatly affects its adhesion to a mating material, and the present invention was completed.

That is, the present invention provides a friction material for brakes consisting of a fiber base material containing at least metal fibers, a filler, and a thermosetting resin, wherein the crystal particles (La, Lc) are 80 to 9
This is a brake friction material characterized by containing 0 nm of graphite.

The metal fibers used in the present invention are steel fibers, brass fibers, and titanium fibers. Fiber base materials other than metal fibers include inorganic fibers such as glass fiber, silica fiber, alumina fiber, rock wool, and potassium titanate fiber, and organic IA fibers such as hemp, cotton, rayon, phenol fiber, and aromatic polyamide fiber. 1f! ! Alternatively, short fibers of 2 fffi or more can be used.

The fiber diameter of the fiber base material is preferably 5 μm to 1100 μm, and the fiber length is preferably o, tmm to 3 mm.

The graphite used in the present invention has crystal grains (La, Lc
) is 80 to 900 m, and the layer spacing (C/2) is 0
．． 3357r+m is preferred. The expression "degree of graphitization" is used to indicate how close the crystal structure of graphite is to an ideal graphite crystal.
- For boat fishing, crystal grains (La, Lc) and interlayer distance t
It is expressed as Ji (C/2).

- For boat fishing, natural graphite crystal particles have a size of 1100 nm or more and a high degree of graphitization, so wear resistance is good, but the coefficient of friction after heat history is low, which is not preferable.

The blending amount of graphite having crystal grains of 80 to 90 nm is preferably 5 to 20% by weight based on the total friction material.

In the present invention, a friction modifier such as cashew dust, rubber dust, barium sulfate, diatomaceous earth, alumina, dolomite, calcium carbonate, etc. can be included as a filler other than graphite having crystal particles of 80 to 90 nm.

Next, the thermosetting resin used in the present invention is one or more of phenol resin, melamine resin, epoxy resin, polyester resin, phenol-modified melamine resin, and oil, rubber, melamine, epoxy, or polyvinyl butyral-modified phenol resin. A mixture is used. The blending amount of these thermosetting resins is preferably 5 to 15% by weight in the total friction material.

Next, the method for manufacturing the asbestos-free friction material for brakes of the present invention is as follows:
This is a conventionally used method and is as follows.

A mixed raw material is produced by thoroughly and uniformly mixing predetermined amounts of the fiber base material, filler, and powdered thermosetting resin using a Banbury mixer, a Henschel mixer kneader, a type blender, or the like. This mixed raw material is filled into a mold and pressed to perform preforming.

This preformed product is heated and pressurized to harden and bond with a thermosetting resin, and then further heat treated to produce a friction material.

[Operations and Effects of the Invention] According to the friction material for brakes of the present invention, crystal particles are 80 to 90 nm in the friction material made of a fiber base material containing at least metal fibers, a filler, and a thermosetting resin. By containing graphite, it has good wear resistance and strong cracking strength between crystal particles, which suppresses adhesion of graphite to the mating material and prevents a decrease in the coefficient of friction during high-temperature braking.

If the crystal grain size is 80 nm without grooves, the wear resistance is insufficient, and if the crystal grain size exceeds 1100 nm, the friction coefficient after thermal history becomes low.

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

Examples 1 and 2 and Comparative Examples 1 and 2 The compositions shown in Table 1 were uniformly mixed using a V-type blender to obtain mixed raw materials. This mixed raw material is heated to a surface pressure of 300 k at room temperature.
A preformed product was obtained by preforming for 20 seconds in a molding machine adjusted to g/c+n'. Rear pressure 300 kg/cm2
The molding machine was heated and pressurized for 7 minutes using a molding machine adjusted to a mold temperature of 150°C. Thereafter, it was heat-treated in a heating furnace at 250° C. for 2 hours and 30 minutes, and after being allowed to cool, it was polished to a predetermined size to obtain a friction material.

Friction materials obtained according to the formulations on each side of Table 1 were subjected to a wear resistance test and a fade resistance test using a brake dynamometer tester. The test results are shown in Table 2.

The method of the wear resistance test was JASO-C427-83 [brake type: PD51g, rotor: 18mm ventilated type, inertia (load): 4. Okg-f
-m-52 Braking initial speed: 50 km/h, deceleration: 0
．． 3G].

The third efficacy test method is JASO-C406-82 [
Brake model: PD51s, rotor: 18vn ventilated type, inertia (load): 5,
Okg-f-m-s2 efficacy after second fade].

(Margin below) (Table 2) Test Results As shown in Table 2, the brake friction material of Example 1.2 had a lower wear rate than the friction material of Comparative Example 1.2.
It can be seen that there is no decrease in the third effect friction coefficient, making it an excellent and well-balanced friction material.

Patent applicant: Aisin Kako Co., Ltd. Representative Haruo Miyaji (Table 1) Mixture composition (Unit: weight%) (Margin below)

Claims (1)

[Claims] (1) A brake friction material consisting of a fiber base material containing at least metal fibers, a filler, and a thermosetting resin, characterized by containing graphite having crystal particles (La, Lc) of 80 to 90 nm. Friction material for brakes.