JPS6023774B2 - Friction material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wet friction material used in an automobile clutch or a mechanical power transmission mechanism.

More specifically, the present invention relates to a friction material based on fibrous material. Conventionally known fibrous-based wet friction materials include cellulose fiber-based materials that are heat-press molded by adding solid powder and phenolic resin (Jiko Sho 46).
-38443), a felt sheet adsorbed with organic activated carbon and a phenol resin are integrally molded under heat and pressure (Japanese Patent Publication No. 46-21123), after heating the pulp and thermosetting resin without applying pressure. , and those molded under heat and pressure (Japanese Patent Publication No. 48-24101) are known.

The main properties required of wet friction materials for braking are friction properties, heat resistance, abrasion resistance, oil retention, and durability.

Among these required characteristics, friction characteristics and oil retention have been improved to a nearly satisfactory level using conventional technology.
In particular, friction materials based on fibers exhibit relatively good performance. However, heat resistance and abrasion resistance are still not at satisfactory levels, and improvements in abrasion performance and durability are strongly desired. The object of the present invention is to provide good frictional properties, which were not available in the prior art.

An object of the present invention is to provide a durable friction material with excellent heat resistance and wear resistance. As a result of intensive research aimed at the above-mentioned purpose, the present inventors have found that heat resistance and abrasion resistance can be improved by simply replacing part of the fibers of conventional paper-based friction materials with aromatic polyamide fibers. We found that there was a significant improvement.

Furthermore, it has been found that stable friction characteristics can be obtained. That is, the present invention relates to a friction material based on fibrous material, in which 5% to 70% of aromatic polyamide fibers are used as a base material, and a paper made by adding a binder and a friction performance improver is used as the base material. This is a friction material made by impregnating phenolic resin with phenolic resin and molding it by heating and pressing. Representative examples of aromatic polyamide fibers include polymetaphenylene isophthalamide fiber (Conex ■) and polyparaphenylene terephthalamide fiber (Kevlar ■), but are not limited to these. It may also be a copolymer.

However, the secondary transition point of the fiber is 200°C or higher, preferably 25°C.
0qo or more is required. The fibers used for the auxiliary fiber materials include cellulose fibers such as cotton, asbestos,
There are inorganic fibers such as glass and carbon, and they are mixed appropriately depending on the purpose of use.

The present invention is characterized in that aromatic polyamide fibers are mixed in place of these existing fiber materials, and the amount of fiber can be determined appropriately depending on the purpose of use, but if it is less than 5%, the heat resistant If it exceeds 70%, the friction properties will deteriorate even if the heat resistance is improved.

The thickness of the fibers is suitably 3 deniers or less, preferably 1.5 deniers or less, and the fiber length is suitably 5 sides or less, preferably 3 ribs or less. When the fibers are thicker than 3 deniers, the surface smoothness of the paper deteriorates, and when the fiber length is 5 sides or more, the cut edges cannot be cut cleanly when the paper is punched into a ring shape. Next, the binder may be commonly used linter pulp, and if necessary, butadiene acrylonitrile or polychloroprene latex may be used in combination. Furthermore, as friction performance improvers, CaC03, mother S0
It may be a commonly used material such as 4Si02, and is not particularly limited.

The particle size of the friction performance improver is suitably 50 microns or less, preferably 10 microns or less. The amount added is 10 to 10% of the base material.
40% is desirable. As the phenolic resin, phenol formaldehyde resin can be used. Examples are shown below, but are not limited thereto.

Examples Aromatic polyamide fibers: 1.5 denier consisting of polymetaphenylene sophthalamide fibers (Conex Teijin registered trademark), length 2 short fibers 3% by weight asbestos fibers 2% by weight linter % by weight of the pulp 2 % by weight of the friction performance improver 3 is dispersed in water at a predetermined concentration, and the dispersion liquid is transferred to a mixer and thoroughly mixed to allow sufficient adsorption between the fibers.

Next, the fibers were formed into a sheet using a paper machine, dried, impregnated with 2% by weight of commercially available phenolic resin, and air-dried. A plate-like lining material was formed by pressing. This was punched out into a ring shape of a required size and bonded to a steel plate base material with adhesive to create a facing material for a green type clutch.
Comparative Example Weight % of asbestos fiber 4, weight % of linter pulp 3
, % by weight of the friction performance improver 3 is dispersed in water at a predetermined concentration, and the dispersion is transferred to a mixer and mixed well to ensure sufficient adsorption between the fibers.

Next, a facing material for a wet type clutch was prepared in the same manner as in the example.

The test method was to use two discs with an inner diameter of 90 ribs and an outer diameter of 120 ribs, and a clutch pressing load of 400 k9 for a rotating body rotating at a rotational inertia mass of 2.4k9/skin/sec2 and a rotation speed of 300pm. Brake, stop, and absorb rotational energy.

The clutch was operated in oil set at 120° C., and the clutch was operated continuously 3000 times at a rate of once every 24 seconds. Figure 1A
1 is a diagram showing the relationship between the number of repeated braking and the time required for the friction material to stop due to braking for a friction material according to the present invention and B for a subordinate product of a comparative example.

B requires a long braking time as well as the number of braking times, whereas A
Although the braking time is short, the braking time is relatively long and stable. FIG. 2 shows a comparison of weight loss due to wear, where A shows the friction material according to the present invention and B shows a conventional product as a comparative example.

As described above, when the friction material according to the present invention is used, good friction characteristics can be obtained, the friction characteristics are stable even after repeated braking operations, and the durability is greatly improved.

Furthermore, by increasing mechanical strength such as heat resistance and abrasion resistance, it becomes possible to reduce the weight and size of the transmission.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the number of brakings and braking time for the product according to the present invention and the conventional product, and Fig. 2 is a graph showing the number of brakings and the weight loss due to wear as a residual weight percentage. Z diagram

Claims (1)

[Claims] 1. A friction material based on fibrous material, which contains 5 to 70% by weight of aromatic polyamide fibers and is made from paper with the addition of a binder and a friction performance improver, and is impregnated with a phenolic resin. Friction material that is molded by heating and pressurizing after tightening.