JP2000026838A - Friction material composition and friction material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction material which has stabilized friction coefficient and can suppress the occurrence of noise and judder by compounding glassy carbon and aluminum nitride in respective specific amounts. SOLUTION: This friction material composition comprises 0.3-23 wt.% of glassy carbon and 0.1-15 wt.% of aluminum nitride in the whole composition. The glassy carbon, for example, is obtained by curing a liquid thermosetting resin, followed by treating carbonization and graphitization, but in this friction material composition, before curing the thermosetting resin, mixing uniformly the aluminum nitride with the thermosetting resin, followed by curing the resulting product through heat treatment, then treating the cured product to the carbonization and graphitization in an inert atmosphere, and grinding and using the resultant. The grain diameter of glassy carbon after the grind is preferably 1-15 μm. The friction material composition may comprise a binder, a reinforcing fiber, a lubricant, a filler or the like, besides the glassy carbon and the aluminum nitride.

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 to obtain organic fibers and inorganic fibers such as aramid fibers, ceramic fibers, and 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 aluminum nitride in the total composition. Further, the present invention relates to a friction material obtained by subjecting the above-mentioned friction material composition to heat and pressure molding.

[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 an abrasive 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. The glassy carbon is obtained by, for example, curing a liquid thermosetting resin, and then performing carbonization and high-temperature treatment (graphitization treatment) in an inert atmosphere. In the present invention, the thermosetting resin is cured. Before the heat treatment, aluminum nitride is uniformly mixed, and then heat-treated to be cured. Thereafter, carbonization and high-temperature treatment (graphitization treatment) are performed in an inert atmosphere, and this is pulverized and used. The particle size of the glassy carbon after pulverization is preferably from 1 to 15 μm,
-11 μm is more preferable.

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, a curing agent such as trichloroacetic acid, paratoluenesulfonic acid, and sulfuric acid is added as necessary in addition to the thermosetting resin. 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] Aluminum nitride is contained in the entire composition.
The content is in the range of 0.1 to 15% by weight, preferably 1 to 13% by weight, more preferably 3 to 10% by weight. Only (μ ≧ 0.35) can be obtained for the target of the coefficient of friction (μ ≧ 0.42). On the other hand, if it exceeds 15% by weight, generation of noise and judder cannot be suppressed. The particle size of aluminum nitride is preferably 1 to 15 μm, and more preferably 2 to 10 μm.

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 aluminum nitride, and if necessary, a metal powder such as brass and bronze is used. Can be 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. The length of the reinforcing fiber varies depending on the material. For example, the inorganic fiber preferably has a length of 15 to 50 mm, more preferably 20 to 45 mm. Organic fibers are preferably 0.8-4 mm,
1-2 mm is more preferred. The metal fiber is preferably 1 to 5 mm, more preferably 2 to 4 mm.

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 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. And then heat-treated. 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 aluminum nitride 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 subjected to a curing treatment to obtain an aluminum nitride-containing resin plate.

Next, the aluminum nitride-containing resin plate is carbonized and fired at 1000 ° C. for 30 days in a nitrogen gas atmosphere, and then heated to 2000 ° C.
Graphitization treatment was performed by holding for a time to obtain glass nitride carbon containing aluminum nitride. The obtained aluminum nitride-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
The coefficient of thermal expansion at 0 to 400 ° C. was 2.6 × 10 ⁻⁶ deg ⁻¹ .

The aluminum nitride-containing glassy carbon obtained above was pulverized to obtain aluminum nitride-containing glassy carbon powder having an average particle diameter of 7 μm. Next, the aluminum nitride-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. Thereafter, it was heated and pressed at 140 ° C. and a pressure of 40 MPa for 12 minutes, and heat-treated 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.

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 based on 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, the disc brake pad of Comparative Example 1 was effective, the disc brake pad of Comparative Example 2 was the actual vehicle abnormal noise occurrence rate, the actual vehicle abnormal noise maximum sound pressure, the effect, the surface attack amount of the mating material, The disc brake pad of Comparative Example 3 has an actual vehicle abnormal noise generation rate, the actual vehicle abnormal noise maximum sound pressure and the amount of attack on the mating material surface, the disk brake pad of Comparative Example 4 is effective, and the disk brake pad of Comparative Example 5 has an actual vehicle abnormal noise generation rate. The maximum sound pressure and the amount of attack on the surface of the opponent material, the disc brake pad of Comparative Example 6 was effective and the amount of attack on the surface of the opponent material. There were defects in the sound pressure and the amount of attack on the surface of the partner material, and good results could not be 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.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takanori Kato 3-3-1 Ayukawacho, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Plant F-term (reference) 3J058 BA21 BA75 BA76 FA01 FA11 FA21 GA07 GA12 GA20 GA22 GA23 GA28 GA33 GA34 GA37 GA45 GA55 GA65 GA92 GA95 4F071 AA41 AA54 AB03 AB12 AB22 AB23 AB28 AB29 AD01 AE11 AE12 AF28 DA01 DA04 DA05

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 aluminum nitride. 2. A friction material formed by heating and pressing the friction material composition according to claim 1.