JPH05320622A - Friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material which hardly makes brake squeak and is excellent in heat resistance, friction characteristics, moldability, etc. CONSTITUTION:A friction material is obtd. by compounding a fibrous material, a filler, and a binder comprising 10-30vol.% thermosetting resin. 1-7vol.% rubber. and 1-7vol.% cashew resin, all the amts. being based on the total compsn. The material is suitable for a clutch facing, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material for disc brake pads, brake linings, clutch facings and the like used in automobiles and the like.

[0002]

2. Description of the Related Art Conventionally, asbestos-based materials have been used as friction materials, but their use has been restricted from the viewpoint of harmfulness to the human body, and as the performance of vehicles has improved, they have been used as friction materials. The required characteristics of are increasing. As a material that meets such requirements, a friction material that does not use asbestos has recently been proposed. For example, fibrous substances such as metal fibers, inorganic fibers, and organic fibers are used as the base material, and inorganic substances are used for these fibrous substances. It is generally known that an organic filler is added, and a thermosetting resin such as a phenol resin or a polyimide resin is further added as a binder to be cured.

[0003]

For example, the phenolic resin used as the above-mentioned binder has high heat resistance, good flowability during thermoforming, and is relatively inexpensive, so that it is used for friction materials used at high temperatures. It is suitable as a binder.

As the phenolic resin, an unmodified type phenolic resin is generally used, but the unmodified type phenolic resin becomes hard because the crosslink density when cured increases. For this reason, it is excellent in heat resistance and mechanical strength, but it does not hit the mating material cast iron badly and the friction coefficient becomes unstable due to the thermal decomposition material generated at the interface between the mating material and the friction material, which causes vibration caused by this. It becomes difficult for the friction material to be absorbed, and there is a drawback that brake squeal (hereinafter referred to as squeal) and vibration are adversely affected.

As a method for solving the above-mentioned drawbacks, there is a method in which a phenol resin is modified with another resin or the like to reduce the crosslink density at the time of curing to give the resin softness. However, in this method, the softness of the resin causes problems such as poor heat resistance and poor flowability during curing.

The present invention solves the above-mentioned drawbacks, reduces the generation of squeal as much as possible, and provides a friction material excellent in heat resistance, friction characteristics, formability and the like.

[0007]

As a result of various investigations on the above-mentioned drawbacks, the present inventors have found that as a binder, a thermosetting resin such as a phenol resin or a polyimide resin is used in the entire composition.
When a binder containing 0 to 30% by volume, 1 to 7% by volume of rubber and 1 to 7% by volume of cashew resin was used, generation of squeal was reduced, and excellent heat resistance was exhibited at high temperature, and stability was obtained. It was found that a friction material excellent in the above-mentioned friction performance, moldability and strength was obtained, and the present invention was completed.

The present invention relates to a friction material containing a fibrous substance, a filler and a binder. The binder is 10 to 30% by volume of thermosetting resin, 1 to 7% by volume of rubber and cashew resin in the entire composition. To a friction material containing 1 to 7% by volume.

In the present invention, examples of the fibrous substance include metal fibers such as steel fibers, copper fibers and brass fibers, glass fibers, ceramic fibers, carbon fibers, rock wool, inorganic fibers such as potassium titanate, aramid fibers and acrylic fibers. , And organic fibers such as phenolic fibers are used.

As the filler, there may be used inorganic fillers such as barium sulfate, magnesium carbonate, calcium carbonate, graphite, antimony trisulfide and metal powder, and organic fillers such as hardened cashew shell oil.

As the thermosetting resin used as the binder, phenol resin, polyimide resin or the like is used. Among them, as the phenol resin, an unmodified phenol resin, a modified phenol resin such as cashew modified, rubber modified, or the like can be used. As the rubber, it is preferable to use powder type rubber, for example, NBR,
SBR or the like is used. As the cashew resin, for example, one obtained by condensing cashew nut shell oil with hexamethylenetetramine is used.

The thermosetting resin is contained in the range of 10 to 30% by volume in the total composition, and if it is less than 10% by volume, the bonding force is remarkably reduced, and cracks and insufficient flowability are apt to occur during thermoforming.
If it exceeds 0% by volume, problems such as friction performance, particularly squealing, are likely to occur. The content of rubber in the whole composition is in the range of 1 to 7% by volume. When it is less than 1% by volume, elasticity disappears and defects such as squeal increase, and when it exceeds 7% by volume, the heat resistance of the rubber is low and abrasion resistance Becomes worse. In addition, the cashew resin is in the range of 1 to 7% by volume, and if it is less than 1% by volume, defects such as squealing will increase, and if it exceeds 7% by volume, wear resistance will be deteriorated due to poor heat resistance of the cashew resin. become worse.

[0013]

[Function] A thermosetting resin is used as a binder in the entire composition in an amount of 10
-30% by volume, 1-7% by volume of rubber and 1-7% by volume of cashew resin cures while maintaining the properties of the respective binders, thus improving heat resistance, friction properties, moldability, etc. It is considered to be excellent, and since it is possible to reduce the amount of pyrolyzed substances generated at the interface between the friction material and the mating material, cast iron, it is considered that vibration is reduced and squeal is improved.

[0014]

EXAMPLES Examples of the present invention will be described below. Examples 1 and 2 and Comparative Examples 1 to 7 The ingredients shown in Table 1 were blended and uniformly mixed with a mixer to form tablets, and then the temperature was 150 ± 2.5.
Thermocompression molding for 5 minutes under the conditions of ℃ and pressure of 49 MPa, and further 2
A disc brake pad was obtained by firing at 00 ° C. for 5 hours.

[0015]

[Table 1]

Next, the disc brake pad which is the friction material according to the present invention and the disc brake pad of the comparative example were mounted on an actual vehicle, and a comparative test of a squeal occurrence state and a comparative test of abrasion resistance were conducted. The test results are shown in Table 2. Table 2 also shows the results of the moldability.

The test conditions are as follows. Squealing state Caliper model: Collet type (cylinder area 25 cm
² ) Test car: 2000cc ... Passenger car Test method: Confirm city streets by general driving (squeal level 5
(Stage evaluation)

[Equation 1]

Wear resistance Caliper model: collet type (cylinder area 25 cm
² ) Test method: inertia: 49 kgm ² , initial braking speed: 6
4 km / hour, deceleration ... 2.94 m / sec ² , braking frequency ...
The amount of wear was measured 1000 times each under the above conditions. Moldability After molding the disc brake pad, the appearance was visually observed. In Table 2, ○ indicates that there is no problem in appearance,
The mark Δ indicates the occurrence of chipping in a part of the molded body.

[0019]

[Table 2]

As is clear from Table 2, the disc brake pad according to the present invention has a small (good) squeal and is excellent in wear resistance and moldability. On the other hand, it can be seen that the disc brake pads of the comparative example have defects in squealing, wear resistance and moldability.

[0021]

The friction material according to the present invention has good moldability,
It is a friction material that is excellent in heat resistance, friction characteristics, etc. and is good against squeal, and is industrially very suitable.

Claims (1)

[Claims] 1. A friction material containing a fibrous substance, a filler and a binder, wherein the binder comprises 10 to 30% by volume of a thermosetting resin, 1 to 7% by volume of rubber and cashew resin as a binder. A friction material containing 1 to 7% by volume.