JPH0959598A - Frictional material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a frictional material composition not lowered in frictional coefficient, maintaining the braking force of a brake, little in the abrasion of a counter material, rotor, and useful for braking automobiles, trucks, industrial machines, etc. SOLUTION: This composition comprises (A) a basic material such as aramid fibers preferably in an amount of 20-48vol.%, (B) a binder such as a phenolic resin preferably in an amount of 15-35vol.%, (C) a friction-controlling agent such as vermiculite preferably in an amount of 27-47vol.%, and (D) an IR dust preferably having particle diameters of <=20 meshes in an amount of 1-15vol.%. Therein, the IR dust is obtained by blending isoprene rubber, a vulcanizing agent therefor, and a cashew nut dust and subsequently curing the blend. The weight ratio of the isoprene/the cashew nut resin is preferably 6/4 to 2/8.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a friction material composition suitable for a friction material used for braking passenger cars, trucks, industrial machines and the like.

[0002]

2. Description of the Related Art Conventionally, as a friction material composition for a brake of an automobile, JP-A-6-128561 and JP-A-5-128561 have been known.
No. 152082, JP-A-2-262149,
As disclosed in JP-A-64-55441, a metal fiber, an inorganic fiber, an organic fiber, a phenol resin or a modified phenol resin as a binder, graphite, cashew dust, an inorganic abrasive as a friction modifier , Barium sulfate and the like have been used. The friction material has been manufactured by stirring and mixing so that these components become uniform, and then heating and pressing.

However, the friction material using the above-mentioned inorganic fiber or inorganic abrasive may sometimes grind the cast iron rotor of the mating material during idling, that is, even when braking is not performed. In particular, if the rotor is non-uniformly ground and unevenly worn, it causes unpleasant vibration not only on the brake pedal but also on the vehicle body during braking.

It is possible to use a lubricant such as graphite in order to improve the grindability. However, if a large amount of the lubricant is used, the coefficient of friction decreases and the braking effect, more specifically, the braking force of the brake is reduced. Tends to get worse.

[0005]

According to the first and second aspects of the present invention, the friction coefficient is not lowered, the braking force of the brake is maintained, and the grindability of the mating rotor is small. A friction material composition for obtaining a friction material is provided. In addition to the object of the invention according to claim 1, the invention according to claim 3 provides a friction material composition in which the fall of the cash resin during mixing is reduced.

[0006]

The present invention comprises a substrate, a binder and a friction modifier, and is obtained by mixing and curing isoprene rubber, a crosslinker of isoprene rubber and a cashew resin in the entire composition. And a friction material composition containing IR dust. Further, the present invention is characterized in that the weight ratio of isoprene rubber to cashew resin is 6: 4 to 2: 8 for isoprene rubber: cashew resin. Furthermore, the present invention is characterized in that the particle size of IR dust is 20 mesh or less.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a base material, organic fibers such as aramid fiber, acrylic fiber, phenol fiber, cellulose fiber and the like similar to those used in conventional friction materials, glass fiber, ceramic fiber, Inorganic fibers such as rock wool, calcium silicate fibers and carbon fibers, and metal fibers such as steel fibers, copper fibers, brass fibers and bronze fibers, or a mixture of two or more kinds of fibers are used. The content of the base material is 20 to 48 with respect to the friction material composition.
A range of volume% is preferred.

Examples of the binder include phenol resins, urea resins, melamine resins, modified resins thereof, aromatic polyimide resins, and polyacetals, and one or more of these can be used. The content of the binder is preferably 15 to 35% by volume with respect to the friction material composition.

Further, as the friction modifier, vermiculite, graphite, those having a lubricating action such as molybdenum disulfide, metal powder (iron, copper, brass, tin), barium sulfate, calcium carbonate, magnesium carbonate, etc. are filled. Agents, zircon sand, alumina, mica, talc, etc. having high Mohs hardness and great grindability, hardened cashew resin, etc., and one or more of these are used, and IR of the present invention Dust is used. The content of the friction modifier is preferably 27 to 47% by volume with respect to the friction material composition.

IR dust is obtained by mixing isoprene rubber, a cross-linking agent for isoprene rubber, and cashew resin, curing the mixture, and then pulverizing the mixture. Crosslinking agents for isoprene rubber include sulfur, zinc oxide, sulfur chloride, selenium,
Tellurium, magnesium oxide and the like are used, and it is preferable to use sulfur and zinc oxide in combination. The cross-linking material is preferably in the range of 5 to 40% by weight based on isoprene rubber. As the cashew resin, a reaction product of cashew nut shell oil and an aldehyde such as paraformaldehyde, formaldehyde or furfural is used. The use ratio of isoprene rubber and cashew resin is preferably in the range of 6: 4 to 2: 8 by weight ratio of isoprene rubber: cashew resin in order to reduce the amount of wear of the rotor. Sulfur and zinc oxide, which are crosslinking agents for isoprene rubber, are preferably used in an amount of 15 to 25% by weight and 5 to 15% by weight, respectively, based on the isoprene rubber in order to obtain a sufficient degree of crosslinking. It is preferable that the particle size of the IR dust is 20 mesh or less, because falling off during mixing is reduced.

In the present invention, the IR dust is in the range of 1 to 15% by volume, preferably 3 to 10% by volume, more preferably 5 to 8% by volume, based on the friction material composition, and less than 1% by volume. However, the effect of reducing the grindability of the rotor cannot be obtained, and if it exceeds 15% by volume, the shear strength decreases, the compression strain increases, and the brake pedal stroke increases. The volume% is a value calculated by dividing the weight by the density. In order to obtain a friction material using the friction material composition according to the present invention, the friction material composition is preformed,
After inserting the back metal and the preform into the mold, the molding may be performed by the heating and pressing method.

[0012]

EXAMPLES Examples of the present invention will be described below. Examples 1 to 4 and Comparative Examples 1 to 2 The components shown in Table 1 were blended and uniformly mixed with a mixer,
Preforming is performed under the condition of pressure of 30 MPa, after which the back metal and the preforming body are inserted into the mold and the temperature is 145 ° C. and the pressure is 40M
Press heat molding for 10 minutes under Pa condition, then 200 ° C
For 5 hours to obtain a disc brake pad.

The IR dusts used in Examples 1 to 4 and Comparative Example 2 were isoprene rubber (Kuraray Co., Ltd., trade name Klaprene IR10), and cashew resin (a product of a reaction product of curnut nut oil and paraformaldehyde). Tohoku Kako Co., Ltd., trade name BD230) is a weight ratio of isoprene rubber: cashew resin 5: 5, and sulfur and zinc oxide as a rubber crosslinking agent are 20% by weight and 10% by weight relative to isoprene rubber, respectively. A mixture having a weight% of mixture was cured, and this was crushed to obtain particles having a particle size in the range of 20 to 100 mesh.

[0014]

[Table 1]

Next, a disc brake pad using the friction material composition according to the present invention and a disc brake pad of a comparative example were rubbed with a friction coefficient at 100 ° C. according to JASO, C406 at 0.75 MPa for 22 hours. The amount of wear of the rotor was measured. The results are shown in Table 2.

[0016]

[Table 2]

As shown in Table 2, it was confirmed that the disc brake pad using the friction material composition of the present invention has a high friction coefficient and a small amount of wear of the rotor. It was also confirmed that the compression strain was small and the shear strength was excellent.

Examples 5 to 8 and Comparative Examples 3 to 4 The components shown in Table 3 were blended and uniformly mixed with a mixer,
Preforming is performed under the condition of pressure of 30 MPa, after which the back metal and the preforming body are inserted into the mold and the temperature is 145 ° C. and the pressure is 40M
Press heat molding for 10 minutes under Pa condition, then 200 ° C
For 5 hours to obtain a disc brake pad.

The IR dusts used in Examples 5 to 8 and Comparative Example 4 were isoprene rubber (Kuraray Co., Ltd., trade name Klaprene IR10) and cashew nuts (resultant of cashew nut shell oil and furfural). Tohoku Kako Co., Ltd.
Made by trade name BD233) in a weight ratio of 5: 5, and sulfur and zinc oxide as a rubber cross-linking agent are mixed with 20% by weight and 10% by weight of isoprene rubber, respectively, and then cured. It was crushed and used with a particle size in the range of 20 to 100 mesh.

[0020]

[Table 3]

Next, the disc brake pad using the friction material composition of the present invention and the disc brake pad of the comparative example were rubbed with the friction coefficient at 100 ° C. according to JASO, C406 at 0.75 MPa for 22 hours. The amount of wear of the rotor was measured. The results are shown in Table 4.

[0022]

[Table 4]

As shown in Table 4, it was confirmed that the disc brake pad using the friction material composition of the present invention has a high friction coefficient and a small amount of wear of the rotor. It was also confirmed that the compression strain was small and the shear strength was excellent.

[0024]

The friction material composition according to the first aspect can provide a friction material having a low grindability of the rotor while maintaining the braking force of the brake without lowering the friction coefficient. The friction material composition according to claim 2 has the effect of the friction material composition according to claim 1, and is particularly excellent in the effect of reducing the grinding of the rotor. The friction material composition according to the third aspect is the first aspect.
And the effect of the friction material composition in 2 is exhibited.

Claims (3)

[Claims] 1. An IR dust containing a base material, a binder and a friction modifier, and containing 1 to 15% by volume of IR dust obtained by mixing and curing isoprene rubber, a crosslinking agent for isoprene rubber and a cashew resin in the entire composition. A friction material composition containing the same. 2. The weight ratio of isoprene rubber to cashew resin is 6: 4 from isoprene rubber to cashew resin.
The friction material composition according to claim 1, which is 2: 8. 3. The friction material composition according to claim 1, wherein the particle size of IR dust is 20 mesh or less.