JPH11209744A - Abrading material composition and abrading material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a stable frictional coefficient and capable of suppressing the generation of a noise and a judder by containing each specific amount of a glassy carbon and a boron carbide. SOLUTION: This abrading material composition contains (A) 0.3-23 wt.%, preferably 0.5-22 wt.%, more preferably 2-20 wt.% glassy carbon, (B) 0.1-15 wt.%, preferably 1-13 wt.%, more preferably 3-10 wt.% boron carbide and, as necessary, (C) 5-20 wt.% binder (e.g.; a phenolic resin), 0.5-16 wt.% reinforcing fiber (e.g.; a copper fiber), 2-8 wt.% lubricant (e.g.; graphite), 10-60 wt.% filler (e.g.; barium sulfate), a metal powder, or the like. The component (A) is obtained by uniformly mixing the component (B) into a liquid state thermosetting resin (e.g.; furan resin), then curing the mixture by heat-treating, then carbonizing and performing a high temperature treatment under an inert atmosphere (graphitizing treatment) and crushing the obtained material. The abrading material is obtained by heat compression molding of this composition.

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 uncomfortable.

[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 organic and inorganic fibers such as aramid fibers and ceramic fibers, and non-steel friction materials using abrasives of inorganic materials in order to obtain a more stable friction coefficient (μ ≧ 0.42) 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]

The present invention relates to a friction material composition comprising 0.3 to 23% by weight of glassy carbon and 0.1 to 15% by weight of boron carbide in the total composition. 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 22% by weight, more preferably from 2 to 20% 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 boronization, the boron carbide is uniformly mixed and then subjected to a heat treatment to harden, followed by carbonization and high-temperature treatment (graphitization treatment) in an inert atmosphere, and pulverized.

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.

[0009] Boron carbide is contained in the total composition in an amount of from 0.1 to 0.1%.
The content is 15% by weight, preferably 1 to 13% by weight, and more preferably 3 to 10% by weight. When the content is less than 0.1% by weight, the effect as a grinding agent functions to some extent, but the stable friction coefficient (μ ≧ 0.42) for the target (μ ≧ 0.
35) can only be obtained. On the other hand, if it exceeds 15% by weight, generation of noise and judder cannot be suppressed.

[0010] The friction material composition of the present invention comprises, in addition to glassy carbon and boron carbide, a binder, a reinforcing fiber, a lubricant,
A filler or the like is used, and if necessary, metal powder such as brass or brass is 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 the lubricant, graphite, antimony sulfide, molybdenum sulfide and the like are used. As the 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 60% by weight, more preferably 20 to 50% 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 in 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 temperature at the time of producing the friction material is preferably from 130 to 170 ° C, more preferably from 130 to 160 ° C. Pressure is 30-6
0 MPa is preferable and 35-55 MPa is more preferable. The heat treatment temperature is preferably 100 to 300 ° C, and 150 to 25 ° C.
0 ° C. is more preferred.

[0014]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. Examples 1 to 9 and Comparative Examples 1 to 8 Resor-type furan resins (manufactured by Hitachi Chemical Co., Ltd., trade name V
P-13N) and boron carbide were blended in the amounts shown in Tables 1 and 2, mixed uniformly, put into 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 cured to obtain a boron carbide-containing resin plate.

Next, the boron carbide-containing resin plate is carbonized and calcined at 1000 ° C. for 30 days in a nitrogen gas atmosphere, then heated to 2000 ° C., and held at 2000 ° C. for 10 hours to perform graphitization. Thus, a boron carbide-containing glassy carbon was obtained. The obtained boron carbide-containing glassy carbon has a thickness of 2.0 to 3.5 mm, a density of 1.58 g / cm ³ , an electrical resistivity of 9000 μΩ-cm, and a thermal expansion coefficient of 20 to 400 ° C. It was 2.6 × 10 ⁻⁶ deg ⁻¹ .

The boron carbide-containing glassy carbon obtained above was pulverized to obtain a boron carbide-containing glassy carbon powder having an average particle diameter of 7 μm. Next, the boron carbide-containing glassy carbon powder and the components shown in Tables 1 and 2 were blended and uniformly mixed by a mixer to obtain a friction material composition. After this, 140 ° C, pressure 4
Heat and pressure molding for 12 minutes under the condition of 0MPa, further 200
Heat treatment was performed at 5 ° 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 status and effectiveness JASO, C402 actual vehicle test was performed on a 2000 cc automatic vehicle (model name Cedric (Y32) manufactured by Nissan Motor Co., Ltd.), and the abnormal noise during the test was measured. The occurrence rate of abnormal noise and the maximum sound pressure were determined. As for the effect, the effect as a disc brake during the test is expressed in μ value,
The amount of attack on the surface of the mating 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 claim 1 can provide a friction material having a stable friction coefficient (μ ≧ 0.42) and capable of suppressing generation of noise and judder. The friction material according to claim 2 has a stable friction coefficient (μ ≧ 0.42) 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 0.1 to 15% by weight of boron carbide. 2. A friction material formed by heating and pressing the friction material composition according to claim 1.