JPH11152460A - Friction material composition, process for producing friction material composition and friction material using the friction material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material composition having a stable friction coefficient, capable of suppressing the generation of noise and judder, and suitable as a friction material, and to provide a process for producing a friction material composition and a friction material produced by using the friction material composition. SOLUTION: This friction material composition includes 0.5-3 wt.% of cashew resin or cashew nut shell liquid and 0.05-3.5 wt.% of quartz sand in the total composition. This process for producing a friction material composition is mixing and kneading cashew resin or cashew nut shell liquid and quartz sand to obtain a preliminary composition, subsequently compounding the preliminary composition with a binder, a reinforcing fiber, a filler and a lubricant, and mixing them. The friction material is obtained by subjecting the friction material composition or a friction material composition obtained by the above process to a forming process under heating and pressing.

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 a friction material composition. Related to 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 Japanese Patent Publication No. 117985, semi-metallic friction materials mainly composed of steel fibers were mainly used, but automatic vehicles have been started in line with the shift to lighter and higher-grade 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 appeared. 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 slowing down from about time, and is a sound of a frequency of about 100 (Hz) in a region where passengers feel 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 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. 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]

The invention according to claim 1 provides a friction material composition suitable for a friction material having a stable friction coefficient and capable of suppressing generation of noise and judder. It is. The invention described in claim 2 provides a method for producing a friction material composition suitable for a friction material having a stable friction coefficient and capable of suppressing generation of noise and judder. The invention according to claim 3 provides a friction material having a stable friction coefficient and capable of suppressing generation of noise and judder.

[0006]

According to the present invention, there is provided a friction material comprising 0.5 to 23% by weight of cashew resin or cashew nut shell liquid and 0.05 to 3.50% by weight of silica sand in the total composition. Material composition. Further, the present invention provides a method of kneading a cashew resin or a cashew nut shell liquid and silica sand to obtain a preliminary composition, and then blending and mixing a binder, a reinforcing fiber, a filler, and a lubricant with the preliminary composition. And a method for producing a friction material composition. Further, the present invention relates to a friction material obtained by subjecting the above-mentioned friction material composition or the friction material composition obtained by the above-mentioned method to heat and pressure molding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the content of cashew resin or cashew nut shell liquid is 0.5 to 23% by weight, preferably 0.6 to 22% by weight in the total composition in terms of solid content. It is preferably in the range of 1 to 20% by weight,
If the content is less than 5% by weight, generation of noise and judder cannot be suppressed. On the other hand, if it exceeds 23% by weight, a stable friction coefficient cannot be obtained.

In the present invention, a curing agent such as hexamethylenetetramine and paraformaldehyde is added, if necessary, in addition to the above cashew resin or cashew nut shell liquid. When a curing agent is added as necessary, the mixing ratio of the cashew resin or cashew nut shell liquid and the curing agent is such that the curing agent is 0.3 to 10 parts by weight with respect to 100 parts by weight of the cashew resin or cashew nut shell liquid. Preferably, the curing agent is in the range of 0.3 to 7 parts by weight with respect to 100 parts by weight of the cashew resin or cashew nut shell liquid.

As the silica sand, powdered silica sand, whisker-like silica sand and the like are used. The content of the silica sand is 0.05 to 3.5% by weight, preferably 0.08 to 3.3% in the total composition.
%, More preferably in the range of 0.1 to 3.0% by weight, and if it is less than 0.06% by weight, a stable friction coefficient cannot be obtained. On the other hand, if it exceeds 3.5% by weight, generation of noise and judder cannot be suppressed.

The friction material composition of the present invention uses a binder, a reinforcing fiber, a lubricant, a filler, etc. in addition to cashew resin or cashew nut shell liquid and silica sand. Metal powder is used.

The binder used in the present invention includes thermosetting resins such as silicone resin and melamine resin, SBR, NBR
And the like. The binder is preferably contained in the entire composition in an amount of 5 to 30% by weight, and 10 to 20.
More preferably, the content is 5% by weight. Further, as a curing agent added as necessary, hexamethylenetetramine, paraformaldehyde, trioxane, or the like is used, and the content is preferably 8 to 14% by weight in the binder,
More preferably, the content is 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 20% by weight, more preferably 3 to 15% by weight.

[0013] 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 in an amount of 2 to 8% by weight, more preferably 3 to 6% by weight. Fillers are present in the total composition at 10-7.
The content is preferably 0% 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 in a mold, molding by a heat and pressure molding method, and then performing a heat treatment. The heating temperature at the time of molding is preferably 130 to 170 ° C, and 140 to 170 ° C.
160 ° C. is more preferred. The pressure is preferably from 30 to 60 MPa, more preferably from 45 to 55 MPa. The heat treatment temperature is preferably from 100 to 300 ° C, more preferably from 150 to 250 ° C.

[0015]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. Examples 1 to 10, Comparative Examples 1 to 9 A cashew resin (manufactured by Hitachi Chemical Co., Ltd., not for sale) and silica sand powder were blended in the amounts shown in Tables 1 and 2, mixed uniformly, and then placed in a warmer. The temperature was raised to 160 ° C. at a rate of temperature increase of 60 ° C./hour, and the coating was cured at 160 ° C. for 5 hours to obtain a silica sand-containing composite. In Tables 1 and 2, the amount of cashew resin is shown as a solid content.

Next, the silica sand-containing composite obtained above was pulverized to obtain a preliminary composition having an average particle size of 7 μm. Next, the preliminary composition was dried at 30 ° C. for 60 minutes to remove water, and then the other materials in the amounts shown in Tables 1 and 2 were blended and uniformly mixed with a mixer to obtain a friction material composition. . Thereafter, the back metal and the friction material composition are inserted and filled in a mold, and the temperature is set to 140 ° C. and the pressure is set to 40 MPa.
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 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. In contrast, as shown in Table 4, it was confirmed that the disc brake pad of the comparative example had a defect in any of the characteristics.

[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 composition obtained by the method according to claim 2 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 3 has a stable friction coefficient (μ ≧ 0.38) and can suppress generation of noise and judder, and is industrially extremely suitable.

Claims (3)

[Claims] 1. The total composition contains 0.5 to 23% by weight of cashew resin or cashew nut shell liquid and 0.05 to 0.05% of silica sand.
A friction material composition containing 3.5% by weight. 2. After kneading a cashew resin or a cashew nut shell liquid and silica sand to obtain a preliminary composition, a binder, a reinforcing fiber, a filler and a lubricant are blended with the preliminary composition and mixed. A method for producing a friction material composition characterized by the following. 3. A friction material formed by heating and pressing the friction material composition according to claim 1 or the friction material composition obtained by the method according to claim 2.