JPH10130629A - Friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material which comprises a filler component and a binder component contg. a fiber component and is excellent in stability of braking performance even when water is present on the surface, hardly causing an abnormal sound, by using, as at least a part of the fiber component, potassium titanate fibers which allow only a small amt. of potassium to dissolve out into 25 deg.C water. SOLUTION: Only potassium titanate fibers which allow potassium in an amt. of 0.1wt.% or lower (based on the total amt. of potassium titanate) to dissolve out into 25 deg.C water is used here. Conventional potassium titanate fibers allow about 1wt.% potassium to dissolve out, and when water is attached, potassium dissolves out into and reacts with water to form a film of hydrated titania, which adversely affects the stability of braking preformance. Potassium hexatitante or octatitanate fibers are used as the potassium titanate fibers. The binder component comprises the fiber component and a thermosetting resin (e.g. a phenol resin). Graphite, barium sulfate, etc., are used as the filler component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake pad, a brake lining, and a clutch mechanism for a vehicle such as an automobile.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material which is used as a shing or the like, and which is less likely to squeal and generate abnormal noise due to brake braking when wet with water and has excellent effect stability.

[0002]

2. Description of the Related Art Conventionally, friction materials used for brake pads, brake linings, clutch facings, and the like of vehicles such as automobiles have often used asbestos as a base material. As a result of pointing out that dust is harmful to the human body, its use is being regulated, and the demand for friction materials that do not use asbestos is increasing.

[0003] Therefore, many non-asbestos-based friction materials which do not use asbestos have been proposed, but fibers such as aramid fiber, potassium titanate fiber, and rock wool are often used as a reinforcing fiber instead of asbestos fiber. In particular, potassium titanate fiber is excellent in heat resistance, abrasion resistance, and fade resistance, and is often used for adjusting physical properties such as porosity.

[0004]

However, when the potassium titanate fiber is used to a certain extent or more, when the friction material surface becomes wet with water, the friction coefficient at the time of brake braking becomes unstable, and sometimes squeals and vibrations occur. It has recently been pointed out that abnormal noise occurs. In particular, the friction coefficient has recently increased after washing due to changes in the shape of wheels and the spread of high-performance car washing machines.
There are cases where abnormal sounds such as squeals and brake vibrations are generated.

[0005] Therefore, the problem to be solved by the present invention is:
In friction materials using potassium titanate fiber with excellent heat resistance and abrasion resistance, even if water adheres to the friction material surface due to car washing, etc., it provides a friction material with excellent braking effect and low noise generation. It is to be.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has the following constitutions: (1) a fiber component, a binder component such as a phenol resin, graphite, barium sulfate; And the like. In a friction material containing a filler component such as above, at least a part of the fiber component has a potassium elution amount in water at 25 ° C. of 0.
(2) The potassium titanate fiber has a potassium elution amount in water at 25 ° C. by an acid or alkali treatment which is equal to or less than 1% by weight of potassium titanate fiber. (1), wherein the potassium titanate fiber is a potassium hexatitanate fiber or a potassium octa titanate fiber; The friction material according to (1) or (2), wherein

That is, the inventor of the present invention has found that a friction material using potassium titanate fiber having excellent heat resistance, abrasion resistance and fade resistance has an excellent stability in braking effect when wet with water. As a result of repeated studies for the purpose of providing a friction material with less sound generation, it was found that the use of potassium titanate fiber having a small amount of potassium elution in water can solve the above-mentioned problems, and accomplished the present invention. Things.

[0008]

Next, the present invention will be described in detail. Potassium titanate is an inorganic compound represented by the general formula K ₂ O · nTiO ₂ , and the potassium titanate fiber usable in the present invention has a potassium elution amount in water at 25 ° C. of 0 to the entire potassium titanate. 1% by weight or less. Incidentally, the potassium elution amount of potassium titanate fiber existing in water is about 1% by weight. When potassium titanate adheres to water, potassium elutes and reacts with water to form a hydrophilic titania hydrate film.
It is considered that this coating has an adverse effect on the effectiveness and stability of the brake and causes abnormal noise.

[0009] Potassium titanate is mainly used in a firing method, a melting method,
Manufactured by hydrothermal method, flux method, melt method,
In the present invention, for example, those in which the amount of potassium eluted is adjusted to 0.1% by weight or less by an acid treatment step or the like can be used. Even when potassium titanate fibers having a potassium elution amount in water of 25 ° C. exceeding 0.1% by weight are produced by the above production method, potassium is eluted in advance with an acid or alkali before use in the present invention. Can be. As the potassium titanate fiber, potassium dititanate fiber, potassium tetratitanate fiber, potassium hexatitanate fiber, and potassium octa titanate fiber are well known. Potassium fibers or potassium octitanate fibers are preferred.

In the present invention, various organic fibers, glass fibers, rock wool, ceramic fibers and other inorganic fibers, as well as potassium titanate fibers, copper, bronze, aluminum and brass are used as the fiber component. And the like. Examples of the binder component include thermosetting resins such as phenolic resin, urea resin, melamine resin, and modified resins thereof, and the filler component includes graphite,
Lubricating materials such as metal powder and cash dust, barium sulfate, calcium carbonate and the like can be mentioned.

The potassium titanate fiber having a potassium elution amount of 0.1% by weight or less in water at 25 ° C. is uniformly mixed with other friction materials by a mixer such as a Ladyge mixer, an Erich mixer or a Henschel mixer. Can be mixed into
Thereafter, the friction material of the present invention can be obtained through conventional molding, heat treatment, and finishing steps. There are no particular restrictions on the conditions such as preliminary molding, heat and pressure molding, and heat treatment after mixing the friction material, and they can be performed by a conventional method.

[0012]

Next, an embodiment of the present invention will be described. First, potassium titanate fibers for Examples and Comparative Examples shown in Table 1 were prepared. About the kind of potassium titanate,
Those labeled "Six titers" are potassium hexatitanate,
What is indicated as "Yachita" indicates potassium octitanate. The amount of potassium eluted indicates the amount of potassium eluted with respect to the entire potassium titanate into water at 25 ° C. Regarding the treatment, those indicated as “acid” indicate that the commercial product was treated with an acid, and those indicated as “alkali” indicate that the commercial product was treated with an alkali.

[0013]

[Table 1]

Examples A to D In addition to the potassium titanate fibers of A to D in Table 1 as the fiber components, aramid fibers and copper fibers were used. A phenol resin was used as a binder component, and graphite was used as a filler component. Using barium sulfate, calcium carbonate, etc., these are uniformly mixed, and preformed at room temperature and a pressure of 400 kg / cm ² ,
The molded body was heated and pressed at a temperature of 150 ° C. and a pressure of 400 kg / cm ² for 10 minutes, and then heat-treated at a temperature of 180 ° C. for 5 hours to obtain friction materials of Examples AD having the compositions shown in Table 2.

Comparative Examples a and b Comparative Examples a and b having the compositions shown in Table 2 in the same manner as in the above Examples except that the potassium titanate fibers of Tables 1 and 2 were used.
The friction material of b was obtained. In addition, the numerical value of Table 2 shows volume%.

[0016]

[Table 2]

The friction materials of Examples and Comparative Examples produced as described above are mounted on an actual vehicle, and the vehicle is washed with a car washer.
Table 3 shows the results of sensory evaluation of the degree of squealing and abnormal noise generated by repeating braking at m / h and a liquid pressure of 20 kg / cm ^2, and the results of a dynamo test measuring changes in friction coefficient before and after car washing.

[0018]

[Table 3]

[0019]

As described above, the friction material of the present invention comprises a fiber component, a binder component such as phenol resin, and a filler component such as graphite and barium sulfate, and at least a part of the fiber component contains water. Incorporation of potassium titanate fibers having a potassium elution amount of 0.1% by weight or less based on the total potassium titanate results in excellent braking stability and stable stability even when water adheres to the friction material surface. Since it produces less sound, it is suitable as a friction material for use in brake pads, brake linings, clutch facings and the like of vehicles such as automobiles.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI F16D 69/02 F16D 69/02 E (72) Inventor Yuji Shishido 1-18-1 Nishiaraimachi, Adachi-ku, Tokyo Nisshin Boseki Co., Ltd. Inside the Tokyo plant (72) Inventor Yoshinori Ozaki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shigeru Ichikawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Mikio Gomi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Keiichi Nishiyama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (3)

[Claims] 1. A friction material containing a fiber component, a binder component such as a phenolic resin, and a filler component such as graphite and barium sulfate.
A friction material comprising potassium titanate fibers having a potassium elution amount into water of 0.1% by weight or less based on the entire potassium titanate. 2. The potassium titanate fiber is a potassium titanate fiber in which the amount of potassium eluted into water at 25 ° C. by an acid or alkali treatment is suppressed to 0.1% by weight or less based on the entire potassium titanate. The friction material according to claim 1, wherein: 3. The friction material according to claim 1, wherein the potassium titanate fiber is a potassium hexatitanate fiber or a potassium octa titanate fiber.