JP2000144104A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material for a brake pad, a lining, or the like, having an improved fade resistance without decreasing a shear strength by including a fibrous talk in the friction material comprising a fiber material, a friction and abrasion-adjusting agent and a binder. SOLUTION: A fiber material such as an aramid fiber or a potassium titanate fiber, a friction and abrasion-adjusting agent such as a graphite, zirconium oxide, a cashew dust or barium sulfate and a binder such as a phenol resin are mixed. The obtained mixture is mixed with a fibrous talk having 2-10 μm average diameter and 10-50 μm average length to form a mixed material. After the obtained mixed material is pressed and pre-formed at a room temperature, the resultant material is molded in a mold, or the like by heating and pressing while degassing. Thus, the objective friction material useful for a brake pad and a lining for a car, a motorcycle, a rolling stock, or the like, and a facing material for a clutch, or the like, and excellent in fade resistance is obtained.

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 brake pads and linings of automobiles, motorcycles, railway vehicles and the like, and a facing material for clutches, and more particularly to a friction material excellent in fade resistance.

[0002]

2. Description of the Related Art Friction materials such as linings of drum brakes of automobiles and pads of disc brakes are required to have various performances such as braking effectiveness, fade resistance, wear resistance, squeal resistance, and high shear strength. . To satisfy this, friction materials containing various fiber base materials, friction and wear modifiers, and binders are used.

[0003] As a fiber base material, metal fibers such as steel fibers,
Inorganic fibers such as asbestos and glass fibers, and organic fibers such as aramid fibers are used. Organic friction modifiers
There are inorganic and metallic ones. The typical organic matter is
Rubber, cashew dust and the like are mainly used for adjusting friction and wear at a relatively low temperature. The inorganic substances are graphite, molybdenum sulfide, barium sulfate, calcium carbonate, silica, magnesium oxide, etc., and the metallic substances are copper, brass,
It is mainly used for adjusting friction and wear at high temperatures.

A phenolic resin, a DAP resin or the like is used as a binder. Generally, the fade property is a phenomenon in which, when repeated braking is performed, the friction coefficient gradually decreases as the friction surface becomes higher in temperature. When it gets hot,
A fade phenomenon occurs because a decomposition gas such as a binder or a friction and wear modifier in the friction material due to frictional heat is present at the interface between the friction material and the mating material.

Therefore, conventionally, a friction material having an increased porosity has been used in order to improve fade resistance.
However, a friction material having an increased porosity has a problem that the strength is reduced. In particular, friction materials whose porosity has been increased by reducing the compounding ratio of organic substances (organic fibers, resin binders, organic friction and wear modifiers), which are sources of decomposition gas, have increased strength due to the decrease in organic fibers and resin binders. However, there was a problem that the water content was reduced.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the conventional problems, and an object of the present invention is to provide a friction material having improved fade resistance without reducing strength.

[0007]

The present inventors have conducted experiments on various combinations of fiber base materials, friction and wear modifiers, and binders. As a result, the addition of talc improves the fade resistance without reducing the strength. It was found that the present invention could be performed, and the present invention was completed. That is, the friction material of the present invention, a fiber substrate, a friction and wear modifier, a binder,
, Characterized by containing fibrous talc.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The friction material of the present invention is a friction material comprising a fibrous base material, a friction and wear modifier and a binder, and contains fibrous talc. Talc is Mg ₃ (S
i ₄ 0 ₁₀ ) (OH) ₂ . Normal talc is scaly, but in the present invention, fibrous talc is used. Since it is fibrous, it has a reinforcing effect and contributes to maintaining the shear strength of the friction material. Fibrous talc has an average diameter of 2 to 10
μm and an average length of about 10 to 50 μm are preferable. The content of fibrous talc is preferably in the range of 1 to 50% by weight. If it is less than 1% by weight, the porosity is low and the fade resistance is not satisfied. If it exceeds 50% by weight, the weight percentage of the friction and wear modifier will be too small, and the friction coefficient before the fade phenomenon will occur will be low.

As the fibrous base material, friction and wear modifier, and binder, those used in conventional friction materials can be used. That is, as the fiber base material, metal fibers such as steel fibers, inorganic fibers such as asbestos and glass fibers, and organic fibers such as aramid fibers can be used. As friction and wear modifiers, rubber, organic substances such as cashew dust, graphite, molybdenum sulfide, barium sulfate, calcium carbonate, silica, magnesium oxide,
And the like and a combination of metals such as copper, brass and zinc.

A phenol resin or a DAP resin is used as the binder. The method of making the lining and pad is the same as the conventional molding method. That is, a friction material having a predetermined shape can be obtained by preforming a mixed material containing a fiber base material, a friction and wear modifier, and a binder at room temperature and then hot pressing.

[0011]

The added fibrous talc functions as a fiber base material to exert a reinforcing effect, and also functions as a friction and wear modifier to maintain fade resistance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an automobile brake pad will be described, and the present invention will be described more specifically. The mixing ratio (% by weight) of the friction material is as shown in Table 1, and the brake pads of three examples were manufactured by changing the amount of fibrous talc added. The fibrous talc used here has an average particle size of 5 μm and an average length of 30 μm. Also, two types of brake pads of comparative examples were manufactured without adding fibrous talc and changing the blending ratio of the organic matter.

In this embodiment, aramid fiber and potassium titanate fiber were used as the fiber base material. Graphite, zirconium oxide, cashew dust, and barium sulfate were used as friction and wear modifiers. A phenol resin was used as a binder. In the example, the amount of barium sulfate was reduced and balanced by the amount of the fibrous talc.

In Comparative Example 1, the mixing ratio of fibrous talc was 0
This is the same as the example except that the mixing ratio of barium sulfate is large. Comparative Example 2 is the same as Comparative Example 1 except that the blending ratio of organic substances (aramid fibers and phenolic resin) was reduced and the blending ratio of barium sulfate was increased accordingly.

[0015]

[Table 1] The brake pads of these examples and comparative examples were manufactured by a molding method. First, the mixed material blended according to Table 1 is pre-formed by pressing at room temperature, and then put into a mold maintained at 160 ° C., and a pressing pressure of 300 kg / cm ² is applied to perform degassing. The molded body was obtained by holding for 10 minutes. The molded body was heated at 200 ° C. for 3 hours to cure the phenolic resin binder, and polished to a predetermined thickness to obtain a brake pad. In addition, a plurality of pads were manufactured for each of the pad of the example and the comparative example for the friction and wear test and the measurement of the shear strength and the porosity.

The first fade coefficient of friction of the brake pads of the embodiment and the comparative example was determined according to the car standard JASO-C427-
83. (Caliper format: PD51,
Rotor: 18mm ventilated type, inertia: 4
kgf · m · s ² ) On the other hand, the shear strength and the porosity were measured using the brake pads not subjected to the friction coefficient measurement according to the automotive standard JASO-444.
It measured according to -78. The shear strength and porosity are shown in Table 1.

From the test results shown in Table 1, the brake pads of Examples 1 to 3 have good or improved fade resistance. On the other hand, Comparative Example 1 has a low porosity and is inferior in fade resistance to the examples. In Comparative Example 2 in which the proportion of the organic substance was reduced, the porosity was high and the fade performance was good, but the strength was low.

[0018]

The friction material of the present invention comprises a fibrous base material, a friction and wear modifier, and a binder, and is characterized by containing fibrous talc. The fibrous talc functions as a fibrous base material to exhibit a reinforcing effect, and also functions as a friction and wear modifier to maintain fade resistance. Therefore, the friction material of the present invention can satisfy the fade resistance without lowering the shear strength.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 101: 00 F term (Reference) 3J056 AA31 BA01 CA16 EA02 EA14 EA23 EA26 EA30 FA03 FA08 3J058 AA01 AA41 BA34 CA02 CA42 GA07 GA12 GA20 GA23 GA24 GA28 GA34 GA35 GA37 GA38 GA43 GA44 GA45 GA50 GA54 GA55 GA64 GA65 GA78 GA86 GA88 GA92 GA93 4F071 AA01 AA32 AD01 AE12 AF28

Claims (3)

[Claims] 1. A friction material comprising a fiber base material, a friction and wear modifier, and a binder, wherein the friction material contains fibrous talc. 2. The fibrous talc has an average diameter of 2 to 10 μm.
The friction material according to claim 1, wherein m and the average length are 10 to 50 m. 3. The friction material according to claim 1, wherein the content of the fibrous talc is in a range of 1 to 50% by weight.