JPH05222353A - Friction material - Google Patents

Abstract

PURPOSE:To provide at a low cost a friction material prevented from causing judder of a brake or other parts without detriment to its frictional coefficient and from decreasing in an effect of preventing the judder as a result of the denaturation of the constituents of the friction material caused by the frictional heat, shearing force, etc., generated during use. CONSTITUTION:The title material comprises a fibrous material, a thermosetting resin, a rubber composition, and carbon black contained in a volume ratio of 2-15% based on the friction material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a friction material, and more particularly to a friction material such as a brake lining, a brake pad and a clutch facing.

[0002]

BACKGROUND OF THE INVENTION Friction materials such as brake linings, brake pads, clutch facings, etc., which have been conventionally used in vehicles and the like, have sufficient performance in practical use under general use conditions. In some cases, "brake squeal" or "judder" may occur in the process of connecting the clutches, which causes a discomfort to the driver of the vehicle or a passenger.

It is said that brake squeal and judder appear when frictional vibrations generated by some cause are magnified and transmitted in these systems when a brake or a clutch is used. The squeal of the brake is not a serious defect that impairs the function of the brake, but it is required to eliminate it from the discomfort in feeling. The judder is a phenomenon in which the vehicle vibrates back and forth in the process of engaging the clutch, and is an inconvenient phenomenon that gives a driver or a passenger an uncomfortable feeling.

In order to prevent such a phenomenon, generally, a lubricant having a layered structure such as graphite, expanded graphite, molybdenum disulfide, a low melting point metal such as lead or a friction modifier such as cashew resin and melamine resin. Is used. However, if graphite is used as a friction modifier, it has the effect of preventing brake squeal and judder, but since it reduces the coefficient of friction, when used for brake linings, etc.,
The braking distance becomes long, and when used as a clutch facing, the function of synchronizing the speeds of the driving side and the driven side may be deteriorated.

When a low-melting metal such as molybdenum disulfide or lead, cashew resin, melamine resin or the like is used, the frictional heat and shearing force generated at the time of use deteriorate these materials to prevent brake squeal and judder. May be lost. Expanded graphite can prevent brake squeaking in a wide temperature range and has almost no decrease in friction coefficient, but expanded graphite is very expensive because it is manufactured by a special manufacturing method.

On the other hand, research has been conducted focusing on the relationship between the thin film formed at the interface between the friction material and the mating material and the brake squeal and the judder phenomenon, for example, Automotive Technology, Vol.45, No.4.
(1991) states that residues formed by carbonization of organic components due to friction form a thin film between the friction material and the mating material, and the thickness and viscosity of the thin film are related to friction characteristics. Has been done. According to this, the more the good quality carbide (graphite-like amorphous carbon) is contained in the coating on the surface of the mating material, the better the dμ / dv characteristic (the change rate of the friction coefficient with respect to the friction speed) becomes, and the front-rear direction when the vehicle starts, etc. It is said that there is little change in acceleration and it is difficult for judder to occur. However, this is an observation of the surface film after friction, and does not mention the carbide contained in the friction material itself.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and can prevent brake squeal and judder without lowering the friction coefficient, and provide a friction material by friction heat or the like. It is an object of the present invention to provide a friction material that is inexpensive and does not deteriorate the constituent materials.

[0008]

SUMMARY OF THE INVENTION A friction material according to the present invention comprises a fiber material, a thermosetting resin, a rubber compound and carbon black, and carbon black is contained in a volume ratio of 2 to the friction material.
It is characterized in that it is mixed in a proportion of -15%.

According to the friction material of the present invention, brake squeal and judder can be prevented without lowering the friction coefficient.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The friction material according to the present invention will be specifically described below. The friction material according to the present invention is formed of a fiber material, a thermosetting resin, a rubber compound and carbon black. The carbon black used in the present invention is a black fine powder obtained by incomplete combustion or thermal decomposition of natural gas or liquid hydrocarbons. This black fine powder is an aggregate of microcrystals having a width of 10 to 30Å and a thickness of 10 to 20Å. The microcrystals form dozens of hexacarbon rings to form a plane, and the planes are parallel to each other. It has a structure in which 3 to 5 sheets are overlapped.

Such carbon black can be produced, for example, by the following method. (1) A method in which natural gas or light oil is used as a fuel to create a violent combustion flow in a combustion furnace, and raw materials (petroleum-based or coal-based heavy oil) are fed into the combustion furnace together with a certain amount of air for incomplete combustion to produce the fuel. (Furness method) (2) A method in which natural gas is incompletely burned in a combustion chamber made of iron, and a flame is made to collide with the surface of a steel channel (gutter-shaped plate) to produce the gas. (Channel Method) (3) A method of introducing acetylene as a raw material into a heat storage furnace and thermally decomposing it. (Acetylene method) (4) Two heat storage furnaces are arranged in parallel using natural gas as a raw material,
A method of alternately storing and pyrolyzing heat. (Thermal method) The true specific gravity of the carbon black thus obtained is usually 1.8 to 1.9.

In the present invention, carbon black having a carbon content of usually 90% or more, preferably 95% or more is preferably used. The particle size of carbon black is not particularly limited, and a particle size suitable for the use of friction material or manufacturing method is selected, but is usually 10 to 500 μm.
m, preferably 10 to 100 μm.

The carbon black is mixed in the friction material in a volume ratio of 2 to 15%, preferably 3 to 12%. If the blending amount is too small, the effect of preventing brake squeal and judder will not be sufficient, and if the blending amount is too large, the frictional force required for brake lining, clutch facing, etc. may be insufficient. Specific examples of the fiber material used in the present invention include glass fibers, metal fibers, ceramic fibers, asbestos, slag fibers, mineral fibers, inorganic fibers such as sepiolite, aramid fibers (aromatic polyamide fibers), polyamide fibers, and cotton. , Hemp, rayon,
Examples include organic fibers such as cellulose fibers, carbon fibers, graphite fibers, and the like.

Of these, glass fiber, aramid fiber, aromatic polyamide fiber, and carbon fiber are preferably used. Such fiber materials are preferably used alone or in combination, and the organic fibers are preferably used in combination with the inorganic fibers. These fiber materials are used in a conventionally known shape such as a roving shape, a yarn shape, a tape shape, a cloth shape, and a flat ring shape.

It is desirable that such a fiber base material is blended in an amount of 20 to 70%, preferably 30 to 60% by volume with respect to the friction material. Specific examples of the thermosetting resin used in the present invention include a phenol resin, a urea resin, a melamine resin, and an epoxy resin. Of these, it is preferable to use a phenolic resin, and examples of the phenolic resin include phenolic resins or modified phenolic resins such as cresol modified phenolic resins, melamine modified phenolic resins, rubber modified phenolic resins and cashew modified phenolic resins.

It is desirable that such a thermosetting resin is mixed in the friction material in an amount of 3 to 30%, preferably 5 to 20% by volume. The rubber compound used in the present invention contains a rubber material and a filler. As the rubber material, specifically, butadiene rubber, styrene-butadiene rubber, isoprene rubber, ethylene-propylene rubber, butyl rubber, acrylonitrile-butadiene rubber,
Examples thereof include synthetic rubber such as acrylic rubber, urethane rubber, silicone rubber, fluororubber, polysulfide rubber, and natural rubber.

Of these, styrene-butadiene rubber and acrylonitrile-butadiene rubber are preferably used. Such a rubber material contains a usual vulcanizing agent or vulcanization accelerator. Examples of the vulcanizing agent include sulfur, zinc oxide, magnesium oxide, organic peroxides, organic sulfur-containing compounds, and alkyl-modified phenol resins. As the vulcanization accelerator, a thiazole-based accelerator,
Sulfenamide-based accelerator, dithiocarbamate-based accelerator, aldehyde amine-based accelerator, guanidine-based accelerator,
Examples thereof include thiourea-based accelerators, xanthate-based accelerators, aldehyde-ammonia-based accelerators, and thiuram-based accelerators.

As the filler, zinc oxide, clay, talc, barium sulfate, aluminum sulfate, cashew dust, graphite, calcium carbonate, bentonite, organic modified bentonite, fine particle silica, carboxymethyl cellulose, sodium bicarbonate, mica, silicon oxide, Metal powder etc. are mentioned. By blending the metal powder, the scavenger effect of scraping off dust and the like adhering to the mating member and the heat dissipation effect of releasing frictional heat and the like are imparted to the friction material. Examples of such metal powder include Al, Cu, Zn and the like, and among these, Al is particularly preferable.

It is desirable that such a rubber compound is compounded in an amount of 5 to 60%, preferably 10 to 50% by volume ratio with respect to the friction material. Next, a method for manufacturing a friction material according to the present invention will be described by taking clutch facing as an example. After adhering the thermosetting resin, the rubber compound containing the carbon black and the filler to the base fiber,
The base fiber is preformed into a spiral shape or a laminate shape, and the obtained preform is then put into a mold, preferably under pressure of 100-200 kgf / cm ² and 150-2.
It heat-compresses and integrates under a temperature condition of 00 ° C. Then, by subjecting to heat curing for 2 to 10 hours under a temperature condition of 180 to 250 ° C., the target clutch facing can be obtained.

[0020]

EXAMPLES Hereinafter, the friction material according to the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

[0021]

EXAMPLE 1 Phenolic resin and a rubber compound containing carbon black were adhered to a glass fiber yarn and molded into a spiral shape to obtain a primary molded product. Each material is
50% glass fiber and 10% phenol resin by volume
The rubber composition was adjusted to 36% and carbon black 4%.

Next, the primary molded product is put into a mold and 1
The mixture was heat-pressed and molded at 80 ° C. for 5 minutes, and then heat-cured in an electric furnace at 220 ° C. for 5 hours to prepare a clutch facing having an outer diameter of 200 mm, an inner diameter of 130 mm and a thickness of 3.5 mm. The carbon black used here was in the form of particles and had a particle size of 10 to 100 μm.

[0023]

[Example 2] The mixing ratio of each material is 50% by volume of glass fiber, 10% of phenol resin, 28% of rubber compound,
Except that the carbon black was adjusted to 12%,
A clutch facing was prepared in the same manner as in Example 1.

[0024]

[Comparative Example 1] The mixing ratio of each material was adjusted so that the volume ratio was 50% of glass fiber, 10% of phenol resin, and 40% of rubber compound (carbon black was not mixed).
A clutch facing was prepared in the same manner as in Example 1 except for the above.

[0025]

[Comparative Example 2] The mixing ratio of each material is 50% by volume of glass fiber, 10% of phenol resin, and 39.5 of rubber compound.
%, And carbon black was 0.5%. A clutch facing was prepared in the same manner as in Example 1.

[0026]

[Comparative Example 3] The mixing ratio of each material is 50% by volume of glass fiber, 10% of phenol resin, 20% of rubber compound,
Except that it was adjusted to 20% carbon black,
A clutch facing was prepared in the same manner as in Example 1.

[0027]

[Comparative Example 4] Flake graphite was used in place of carbon black, and the mixing ratio of each material was glass fiber 50 by volume ratio.
%, Phenol resin 10%, rubber compound 28%, and scaly graphite 12% to prepare a clutch facing in the same manner as in Example 1.

The "magnitude of frictional vibration" and "friction coefficient" were measured using the clutch facings prepared above. The results are shown in Table 1. In the present invention, the magnitude of frictional vibration is determined by attaching the created clutch facing to a frictional vibration measuring machine, measuring the torsional torque of the drive shaft when the clutch is engaged, and measuring the maximum torque (T _max ) and the minimum torque (T _max ). T _min ) and the difference (T; T = T _max −T _{m in} ).
Was calculated and evaluated as follows.

T ≦ 49 N · m (5 kgf · m)… Small vibration 49 N · m <T ≦ 147 N · m (15 kgf · m)… During vibration 147 N · m <T… Large vibration Also, the friction coefficient is inertial braking. It measured using the friction tester.

[0030]

[Table 1]

[0031]

According to the present invention, brake squeal and judder can be prevented without lowering the friction coefficient. Further, the friction material of the present invention, the frictional heat generated during use, the material constituting the friction material is changed due to shearing force,
The effect of preventing brake squeal and judder does not decrease. Furthermore, since an inexpensive material is used, a friction material having such excellent properties can be provided at low cost.

Claims (1)

[Claims] 1. A fiber material, a thermosetting resin, a rubber compound and carbon black, wherein the carbon black is 2 to 1 in volume ratio to the friction material.
A friction material characterized by being mixed in a ratio of 5%.