JPH10330732A - Friction material composition and friction material made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can give friction materials having stable coefficient of friction and suppressed in the production of noise or judder by mixing a glassy carbon with silicon carbide in a specified ratio. SOLUTION: A thermosetting resin of 100 pts.wt. such as a furan resin, a phenolic resin, an epoxy resin, an unsaturated polyester resin or a melamine resin is mixed with 0.3-10 pts.wt. curing agent such as trichloroacetic acid or p-toluenesulfonic acid and silicon carbide, and the mixture is carbonized and subjected to high-temperature treatment in an inert atmosphere, and the product is ground to obtain a grinding agent containing 0.3-23 wt.% glassy carbon and 0.03-12 wt.% silicon carbide. The grinding agent is mixed with 0.5-16 wt.% reinforcing fibers such as glass fibers or ceramic fibers, 2-8 wt.% lubricant such as graphite, antimony sulfide or molybdenum sulfide, a filler such as cashew dust or a rubber dust, 5-20 wt.% binder such as a phenolic resin and optionally 8-14 wt.% curing agent such as hexamethylenetetramine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material composition suitable for a friction material such as a disc brake pad and a brake lining used for braking automobiles, railway vehicles, various industrial machines, and the like, and to use of the friction material composition. Friction material.

[0002]

2. Description of the Related Art Friction materials such as disc brake pads and brake linings are used in automobiles, railway vehicles, various industrial machines and the like for braking. Conventionally, as this friction material, Japanese Patent Application Laid-Open No.
As shown in JP-A-117985, semi-metallic friction materials containing steel fibers as a main constituent fiber were the mainstream, but automatic vehicles were launched in line with the shift to lighter and more sophisticated automobile industries. Problems such as generation of abnormal noise at the time of stoppage and stoppage, insufficient braking force at low temperatures, and wheel contamination due to abrasion powder have come up. The abnormal noise generated here has a speed of 30 km /
This is noise (sound pressure of 70 dB or more) associated with braking of the friction material that appears in the process of decelerating from about time, and is a sound of a frequency of about 100 (Hz) in a region where a passenger feels discomfort.

[0003] In order to solve these problems, non-ferrous metal fibers such as copper fiber and brass fiber are used instead of steel fiber.
The transition to non-steel friction materials using abrasives of inorganic materials in order to obtain organic fibers and inorganic fibers such as aramid fibers, ceramic fibers, and more stable friction coefficient (μ ≧ 0.38) has rapidly progressed. .

In the prior art, the friction coefficient has been stabilized by the above-mentioned inorganic material abrasive. However, the abrasive attacks the metal (rotor) of the counterpart material, and in the process, squeal noise and abnormal noise are generated. There is a disadvantage that noise such as sound and judder are generated. In order to prevent the generation of noise and judder, the use of the abrasive may be stopped or the amount of the abrasive may be reduced, but in this case, a stable friction coefficient cannot be obtained. SiO ₂ , Al ₂ O ₃ , ZrO ₂ , ZrS
When an abrasive containing an oxide such as iO ₃ is used, there is a disadvantage that carbon constituting glassy carbon disappears.
At present, a friction material having a stable friction coefficient and completely suppressing generation of noise and judder has not been obtained by using a material other than the current inorganic material-based abrasive.

[0005]

SUMMARY OF THE INVENTION The present invention provides a friction material composition suitable for a friction material having a stable friction coefficient and capable of suppressing generation of noise and judder. is there. The invention described in claim 2 provides a friction material having a stable friction coefficient and capable of suppressing generation of noise and judder.

[0006]

According to the present invention, 0.3 to 23% by weight of glassy carbon and 0.1 to 0.2% by weight of silicon carbide are contained in the whole composition.
The present invention relates to a friction material composition containing from 03 to 12% by weight.
The present invention also relates to a friction material obtained by heating and pressurizing the above friction material composition.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the content of glassy carbon in the total composition is from 0.3 to 23% by weight, preferably from 0.5 to 20% by weight, more preferably from 5 to 10% by weight. When the content is less than 0.3% by weight, the effect as a grinding agent does not function sufficiently, and a stable friction coefficient cannot be obtained. On the other hand, if it exceeds 23% by weight, generation of noise and judder cannot be suppressed. Glassy carbon can be obtained by, for example, curing a liquid thermosetting resin, and then carbonizing and high-temperature treatment (graphitization treatment) in an inert atmosphere. In the present invention, the thermosetting resin is cured. Before the silicon carbide is uniformly mixed, heat treatment is performed and hardening is performed, and then carbonization and high temperature treatment (graphitization treatment) are performed in an inert atmosphere.

The thermosetting resin for obtaining the glassy carbon is not particularly limited, and examples thereof include a furan resin, a phenol resin, an epoxy resin, an unsaturated polyester resin, a melamine resin, an alkyd resin, and a xylene resin. . Further, a mixture of the above resins may be used. In the present invention, if necessary in addition to the above thermosetting resin,
A curing agent such as trichloroacetic acid, paratoluenesulfonic acid, sulfuric acid and the like is added. When a curing agent is added as necessary, the mixing ratio of the thermosetting resin and the curing agent is preferably in the range of 0.3 to 10 parts by weight of the curing agent per 100 parts by weight of the thermosetting resin. More preferably, the curing agent is in the range of 0.3 to 7 parts by weight based on 100 parts by weight of the conductive resin.

Further, silicon carbide is contained in an amount of 0.03 to 1 in the total composition.
2% by weight, preferably 0.05 to 10% by weight, more preferably 0.05 to 10% by weight;
If it is less than% by weight, a stable friction coefficient cannot be obtained. On the other hand, if it exceeds 12% by weight, generation of noise and judder cannot be suppressed.

In the friction material composition of the present invention, a binder, a reinforcing fiber, a lubricant, a filler and the like are used in addition to glassy carbon and silicon carbide. If necessary, a metal powder such as brass and brass is used. Used. The binder used in the present invention is preferably a phenol resin, and particularly preferably a novolak resin, a solid ammonia resol resin, a silicon-modified phenol resin, or an acrylic-modified rubber phenol resin. In the present invention, a curing agent is added to the binder as needed. The binder is present in the total composition at 5-2.
The content is preferably 0% by weight, more preferably 8 to 14% by weight. As a curing agent added as needed, hexamethylenetetramine, paraformaldehyde, trioxane, or the like is used.
The content is preferably 4% by weight, more preferably 10 to 12% by weight.

Examples of the reinforcing fibers include inorganic fibers such as glass fibers, ceramic fibers, carbon fibers, and mineral fibers; organic fibers such as aramid fibers, polyamide fibers, and polyimide fibers; and metal fibers such as copper fibers, brass fibers, and steel fibers. Used. The reinforcing fiber is preferably contained in the entire composition in an amount of 0.5 to 16% by weight, more preferably 3 to 10% by weight.

As a lubricant, graphite, antimony sulfide, molybdenum sulfide and the like are used. As a filler, cashew dust, rubber dust, barium sulfate, calcium carbonate, magnesium carbonate, silica, metal powder and the like are mixed. Used as The lubricant is preferably contained in the entire composition at 2 to 8% by weight, more preferably at 3 to 6% by weight. The filler is preferably contained in the entire composition in an amount of 10 to 70% by weight, more preferably 20 to 60% by weight. The usage ratio of each component constituting the friction material composition is adjusted so that the total amount thereof becomes 100% by weight.

The friction material according to the present invention is obtained by inserting and filling a backing metal and a friction material composition into a mold, and then integrally molding by a heat and pressure molding method, or by using an adhesive after heating and pressure molding. It is obtained by bonding to the back metal and then performing heat treatment. The heating and pressurizing conditions for producing the friction material and the heat treatment conditions for the subsequent steps are not particularly limited, and are performed under conventionally known conditions.

[0014]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. Examples 1 to 7 and Comparative Examples 1 to 6 Resor-type furan resins (manufactured by Hitachi Chemical Co., Ltd., trade name V
P-13N) and silicon carbide were blended in the amounts shown in Tables 1 and 2 and mixed uniformly, then placed in a warmer, heated to 160 ° C at a rate of 10 ° C / hour, and heated at 160 ° C for 5 hours. The resin was held and subjected to a curing treatment to obtain a silicon carbide-containing resin plate.

Next, the silicon carbide-containing resin plate is carbonized and fired at 1000 ° C. for 30 days in a nitrogen gas atmosphere, then heated to 2000 ° C., and held at 2000 ° C. for 10 hours for graphitization. Thus, silicon carbide-containing glassy carbon was obtained. The obtained silicon carbide-containing glassy carbon has a thickness of 2.
Within the range of 0 to 3.5 mm, the density was 1.56 g / cm ³ , the electrical resistivity was 10,000 μΩ-cm, and the coefficient of thermal expansion at 20 to 400 ° C. was 2.2 × 10 ⁻⁶ deg ⁻¹ .

The silicon carbide-containing glassy carbon obtained above was pulverized to obtain silicon carbide-containing glassy carbon powder having an average particle diameter of 7 μm. Next, this silicon carbide-containing glassy carbon powder and
And the components shown in Table 2 were blended and uniformly mixed with a mixer to obtain a friction material composition. After this, 140 ° C, pressure 400MP
Heat-press molding was performed under the condition of a for 12 minutes, and heat treatment was further performed at 200 ° C. for 5 hours to obtain a disc brake pad.

[0017]

[Table 1]

[0018]

[Table 2]

Next, a comparative test was performed on the disc brake pad according to the present invention and the disc brake pad of the comparative example. The test results are shown in Tables 3 and 4. The test conditions are as follows. Shear strength The strength at 22 ° C and 300 ° C was measured according to JASO, C427. Wear resistance Caliper model: Collet type (cylinder area 28.8
cm ² ) Test conditions: Inertia according to JASO, C427 ... 4
9kgm ² , initial braking speed: 60km / h, deceleration: 2.94
m / sec. ^2, braking before temperature ... 250 ℃, braking number of times ... each 100
The wear amount was measured under the condition of every 0 times.

[0020] Abnormal noise generation situation and effectiveness JASO, C402 actual vehicle test was performed on a 2000cc automatic car (Nissan Motor Co., Ltd., model name Cedric (Y32)), and the abnormal noise during the test was measured, and 70dB or more. The occurrence rate of abnormal noise and the maximum sound pressure were determined. Regarding efficacy,
The effectiveness as a disc brake during the test was evaluated by the μ value, and the amount of attack on the surface of the partner material was evaluated by the amount of grinding of the rotor. Formability The appearance of the disc brake pad was visually observed, and the occurrence of wrinkles and cracks was observed.

[0021]

[Table 3]

[0022]

[Table 4]

As shown in Table 3, it was confirmed that the disc brake pad according to the present invention was free from wrinkles and cracks and was excellent in all properties. On the other hand, as shown in Table 4, in the disc brake pad of the comparative example, a defect occurred in any of the characteristics, and good results were not obtained.

[0024]

The friction material composition according to the first aspect can provide a friction material having a stable friction coefficient (μ ≧ 0.38) and capable of suppressing generation of noise and judder. The friction material according to claim 2 has a stable friction coefficient (μ ≧ 0.38) and can suppress generation of noise and judder, and is industrially extremely suitable.

Claims (2)

[Claims] 1. A glassy carbon in a total composition of 0.3 to 2%.
A friction material composition containing 3% by weight and 0.03 to 12% by weight of silicon carbide. 2. A friction material formed by heating and pressing the friction material composition according to claim 1.