JP2000219873A - Heat resistant dry type frictional material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat resistant dry type frictional material showing an excellent abrasion resistance even at a high temperature, also having a high strength as a non-rock wool-based material and useful as a brake pad, etc. SOLUTION: This frictional material containing a reinforcing fiber other than a rock wool and a binder such as a phenolic resin, and a friction-adjusting agent such as barium sulfate, is provided by containing 0.5-50 vol.% potassium titanate as a part of the above reinforcing fiber based on the total amount and also 0.5-30 vol.% graphite containing >=40 wt.% that having <=300 μm particle diameter as a part of the above friction-adjusting agent based on the total amount. Since the material uses potassium titanate as the part of the reinforcing fiber other than the rock wool, the dust of the rock wool which is poisonous to a human body, is not generated, and also the graphite containing fine graphite made to have a prescribed particle diameter or less as the part of the friction adjusting agent, elevates heat conductivity and also absorbs oxygen at a high temperature to prevent the deterioration of the friction material, and it is possible to be equipped with sufficient high temperature frictional characteristics even by using potassium titanate having a low heat conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-asbestos-based heat-resistant dry friction material used as a brake pad, a brake lining, a clutch facing of a vehicle, an industrial machine, and the like. The present invention also relates to a non-asbestos-based heat-resistant dry friction material which exhibits excellent wear resistance and high strength.

[0002]

2. Description of the Related Art Conventionally, as a friction material, a material containing asbestos as a main component has been widely used, but it is pointed out that asbestos dust, which cannot be avoided, is toxic to the human body. As a result, the use of asbestos-based materials has been restricted due to the fact that their use is being regulated, and secondly, higher performance friction materials have become necessary as vehicles have become more sophisticated. There is an increasing demand for friction materials that have higher performance and do not use asbestos.

[0003] Recently, many proposals have been made for friction materials that do not use asbestos, and most of them use aramid fiber, glass fiber or metal fiber as a base material.

[0004]

However, the friction material using aramid fiber, glass fiber or metal fiber has various problems. That is, the friction material using aramid fiber has a problem that when a brake is used continuously, the surface temperature of the friction material increases, and the aramid fiber may be thermally decomposed and cracked. The friction material using fibers has a problem that the glass fibers fall off at a high temperature and the amount of wear increases.

[0005] Further, friction materials using metal fibers have the advantage of being excellent in abrasion resistance and fade resistance at high temperatures, but they are bulky, easily rust, and ignite at high temperatures. It is possible and dangerous, and the friction material using the glass fiber or the metal fiber may have the possibility of shaving or damaging the other side, such as a rotor or a drum.

Of course, friction materials using materials other than those described above have been provided, but many of them have insufficient high-temperature characteristics such as abrasion resistance at a high temperature of 400 ° C. or higher and have unstable friction behavior. It was.

The present invention has been made to solve the above-mentioned disadvantages of the prior art.

[0008]

Means for Solving the Problems and Embodiments of the Invention The above objects have been achieved, and at normal operating temperatures, of course,
A configuration adopted by the present invention to provide a non-asbestos-based dry friction material having stable friction performance because of exhibiting excellent wear resistance even at a high temperature of 400 ° C. or higher, and having high strength and excellent heat resistance. Is a friction material containing reinforcing fibers other than asbestos, a binder such as phenolic resin, and a friction modifier such as barium sulfate, wherein potassium titanate fiber as a part of the reinforcing fibers is 0% based on the total amount of the friction material. .5 to 50
% Of graphite and, as a part of the friction modifier, 0.5 to 30% by volume of graphite containing 40% by weight or more of particles having a particle size of 300 μm or less based on the total amount of the friction material. Or, or in a friction material containing a reinforcing fiber other than asbestos and a binder such as phenolic resin and a friction modifier such as barium sulfate, as a part of the reinforcing fiber,
Potassium titanate fiber whose surface is coated with a metal or a thermosetting resin is 0.5% of the total amount as a friction material.
Or 50% by volume, or a friction material containing a reinforcing fiber other than asbestos, a binder such as a phenolic resin, and a friction modifier such as barium sulfate. Contains 0.5 to 50% by volume of potassium titanate fiber whose surface is coated with a metal or a thermosetting resin with respect to the total amount as a friction material, and has a particle diameter of 300 μm or less as a part of the friction modifier. Characterized by containing 0.5 to 30% by volume of graphite containing not less than 40% by weight of the total amount as a friction material.

Hereinafter, the present invention will be described in detail. As the reinforcing fiber used in the present invention, potassium titanate fiber represented by the formula K ₂ Ti ₆ O ₁₃ or the like or an organic fiber such as aramid fiber, acrylic fiber, phenol fiber, PVA fiber or the like, or Glass fibers, inorganic fibers such as carbon fibers, and a mixture containing one or more fibers of metal fibers such as steel fibers, copper fibers, and bronze fibers are used. In short, a part of the reinforcing fibers is used. As long as it contains potassium titanate fiber.

The potassium titanate fiber may be one whose surface is coated with a metal or a thermosetting resin. Examples of the metal for surface treatment include copper and nickel. Similarly, examples of the thermosetting resin include a phenol resin and an epoxy resin that are widely used as a binder in a friction material.

As the binder, a thermosetting resin such as a phenol resin is used, and as the friction modifier, cashew dust, barium sulfate, calcium carbonate and the like are used, and these are widely used in ordinary friction materials. In the present invention, however, the friction modifier contains graphite containing a predetermined amount or more of fine graphite having a predetermined particle size or less.

The ratio of each of the above components is preferably 0.5 to 50% by volume of the reinforcing fiber with respect to the total amount of the friction material.
(Hereinafter,% relating to the component ratio indicates volume%.) The binder is 5 to 30%, the friction modifier is 20 to 80%, and the graphite is 0.5 to 30% with respect to the total amount of the friction material. ,
As this graphite, one containing 40% by weight or more having a particle size of 300 μm or less is used.

[0013]

According to the present invention, since potassium titanate fiber is used as a part of the reinforcing fiber other than asbestos, no asbestos dust toxic to the human body is generated, and the friction modifier is used. As a part of graphite containing a predetermined amount of fine graphite with a predetermined particle size or less, increases the thermal conductivity and absorbs oxygen at high temperatures to prevent deterioration of the friction material,
Even when potassium titanate fibers having low thermal conductivity are used, sufficient high-temperature friction characteristics can be provided.

Further, since potassium titanate fiber whose surface is coated with a metal or a thermosetting resin is used as a part of the reinforcing fiber, the potassium titanate fiber is easily blended with other components during the production of the friction material. It is possible to reduce bubbles around the potassium titanate fiber, which cannot be normally avoided, and prevent the invasion of oxygen to prevent the friction material from deteriorating.

[0015] Further, potassium titanate fiber whose surface is coated with a metal or a thermosetting resin is used as a part of the reinforcing fiber, and at the same time, fine graphite having a predetermined particle size or less is used as a part of the friction modifier. When a graphite containing a predetermined amount of is used, it is possible to further obtain a friction material having excellent friction characteristics at high temperatures.

[0016]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 First, graphite containing a predetermined amount of fine graphite having a predetermined particle size or less as described below was prepared. Graphite A: 10 to 20% contained 300 μm or less Graphite B: 20 to 40% contained 300 μm or less Graphite C: 40% or more contained 300 μm or less, the balance being 1,000 to 300 μm particle size belongs to.

Next, a mixture containing potassium titanate fiber and graphite was uniformly mixed in the proportions shown in Table 1 (the numbers in the table represent% by volume). Examples A to E were compression molded at a pressure of 200 kg / cm ² for 7 minutes and then heat-treated at 180 ° C. for 5 hours.
Was obtained. On the other hand, those obtained by variously changing the blending of the reinforcing fibers and the friction modifier were mixed uniformly, and friction materials a to f of comparative examples were obtained in the same manner as above.

The friction materials thus obtained in Examples and Comparative Examples were subjected to a friction test in accordance with the friction performance test method specified in JASO C406 "Test Method for Dynamometer of Passenger Car Brake Apparatus". For the friction material, the state of crack generation was examined. Table 2 shows the friction coefficient when the surface temperature of the friction material during the fade test is 100 ° C., 400 ° C., and 450 ° C., the wear amount of the friction material after the test, and the state of crack generation.

[0020]

[Table 1]

[0021]

[Table 2]

Example 2 First, a potassium titanate fiber was coated with copper by an electroless plating method to prepare a potassium titanate fiber A.
The solution was melted at ℃, potassium titanate fiber was put therein, stirred, cooled, and pulverized to prepare potassium titanate fiber B.

The above-mentioned mixture containing the potassium titanate fibers A and B was uniformly mixed at the ratios shown in Table 3 (the numbers in the table represent% by volume), and the mixture was treated in the same manner as in Example 1. Thus, the friction materials of Examples F to O were obtained. As the graphite, the one described as graphite C in Example 1, that is, graphite containing 40% or more having a particle size of 300 μm or less was used.

On the other hand, those obtained by variously changing the blending of the reinforcing fibers and the friction modifier were mixed uniformly, and friction materials g to j of comparative examples were obtained in the same manner as described above. The friction materials thus obtained in Examples and Comparative Examples were subjected to a friction test in the same manner as in Example 1 and the state of occurrence of cracks was examined. The results are shown in Table 4 below.

[0025]

[Table 3]

[0026]

[Table 4]

Since the present invention is as described above, a vehicle,
Brake pads and brake linings for industrial machinery, etc.
Excellent as a non-asbestos-based friction material used as clutch facing.

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Claims (3)

[Claims] 1. A friction material containing reinforcing fibers other than asbestos, a binder such as phenolic resin, and a friction modifier such as barium sulfate, wherein potassium titanate fibers are used as a part of the reinforcing fibers in a total amount as a friction material. And 0.5 to 50% by volume, and a particle size of 3 as a part of the friction modifier.
A heat-resistant dry-type friction material comprising 0.5 to 30% by volume of graphite containing not more than 00 μm and not less than 40% by weight of graphite. 2. A friction material containing reinforcing fibers other than asbestos, a binder such as phenolic resin, and a friction modifier such as barium sulfate, wherein the surface of the reinforcing fibers is made of a metal or a thermosetting resin as a part of the reinforcing fibers. A heat-resistant dry friction material comprising 0.5 to 50% by volume of the coated potassium titanate fiber based on the total amount of the friction material. 3. A friction material containing reinforcing fibers other than asbestos, a binder such as phenolic resin, and a friction modifier such as barium sulfate, wherein the surface of the reinforcing fibers is made of a metal or a thermosetting resin as a part of the reinforcing fibers. It contains 0.5 to 50% by volume of the coated potassium titanate fiber based on the total amount of the friction material, and has a particle size of 30 as a part of the friction modifier.
A heat-resistant dry-type friction material containing 0.5 to 30% by volume of graphite containing 40% by weight or more of a material having a particle size of 0 μm or less with respect to the total amount of the friction material.