JPS61278586A - Extrudable friction material - Google Patents

Abstract

PURPOSE:To obtain the titled friction material which causes no high temp. fading and is excellent in mass producibility etc., by incorporating an arom. polyamide fiber and an adhesive contg. a thermosetting resin, a rubber material, etc., and a metal oxide powder as a high-temp. fading inhibitor. CONSTITUTION:An intended extrudable friction material is obtd. by incorporating an arom. polyamide fiber as a base material, an adhesive compsn. contg. a thermosetting resin (e.g.: phenolic resin), a rubber material (e.g.: butadiene rubber), etc., a metal oxide powder as a high-temp. facing inibitor (e.g.: calcined aluminum powder or zinc oxide powder). The use of the present material enables mass production of frictional materials suitable for use in buffer material of a clutch disc, a brake shoe of a washing machine, which are excellent in cushioning properties and flexibility, undergoes no lowering in friction coefficient, without use of any asbestos which has an adverse effect on human body.

Description

[Detailed Description of the Invention] The present invention relates to a friction material that can be extruded and used as a cushioning material for clutch desks, a plexi for washing machines, etc. The present invention relates to a formed extrudable friction material.

Technical Background and Problems Friction materials are used in clutch discs, rotating cylinders of washing machines, etc. to provide a buffering effect. It is desirable that such a friction material has a high coefficient of friction, excellent wear resistance, cushioning properties, and flexibility such that it will not break even when wrapped around a rotating tube, for example.

Such friction materials have traditionally been manufactured using asbestos as a base material, but in recent years, asbestos resources have been depleted and the resulting difficulty in obtaining them has arisen, as well as the negative effects of asbestos on the human body have been pointed out. Its use is beginning to be reconsidered.

For this reason, the inventors of the present invention conducted intensive studies to manufacture friction materials from base fibers other than asbestos, and discovered the following fact. In other words, when trying to manufacture a friction material using rigid inorganic fibers such as glass fibers as a base material instead of asbestos, it becomes difficult to manufacture a sheet-like material using an extruder at a low temperature of about 50°C from room temperature. Each friction material must be heated and compressed one by one, which significantly reduces mass productivity and increases costs, as well as making it impossible to obtain products with excellent cushioning properties and flexibility. . On the other hand, when manufacturing friction materials using aromatic polyamide fibers or fibrillated aromatic polyamide fibers as the base fiber instead of asbestos, it is possible to manufacture sheets in the form of sheets using an extruder at low temperatures and mass production. Although it has excellent properties, the resulting friction material has poor heat resistance and is
At a high temperature of about 200° C., a serious problem arises in that the coefficient of friction decreases significantly.

The present inventors investigated how to reduce the reduction in the coefficient of friction, that is, the high-temperature fade phenomenon, when friction materials containing aromatic polyamide fibers as a base material are used under high-temperature conditions. Specifically, the present invention has been completed by discovering that the above problems can be solved all at once.

The present invention enables extrusion molding from base fibers other than asbestos, has excellent mass productivity, has cushioning properties and flexibility, and has a low coefficient of friction even when used under high temperature conditions. The purpose of the present invention is to provide a friction material that does not show any decrease in friction.

Applications 5 and 1 The friction material according to the present invention comprises aromatic polyamide fibers as a base material, a binder composition containing a thermosetting resin and a rubber material, and a metal oxide powder as a high temperature fade preventive agent. It is characterized by containing.

As a metal oxide powder as a high temperature anti-fade agent,
Calcined alumina powder, zinc oxide powder, lead oxide powder, etc. are mainly used.

Fake original copy The friction material according to the present invention will be specifically explained below.

The friction material according to the present invention contains aromatic polyamide fibers as base fibers. As this aromatic polyamide fiber, fibrillated aromatic polyamide fiber is preferably used. Such aromatic polyamide fibers are commercially available from DuPont as Kevlar or Kevlar pulp.

A binding composition made of a thermosetting resin and a rubber material is attached to such aromatic polyamide fibers. As the thermosetting resin, specifically, phenol resin, urea resin, melamine resin, epoxy resin, etc. are used. Among these, phenol resins are preferred, and the phenol resins used include novolak type, resol type, and modified phenol resins such as cresol-modified, melamine-modified, rubber-modified, and oak-modified.

Rubber materials include butadiene rubber (BR) and styrene rubber.
Butadiene rubber (SBR), isoprene rubber (■R),
Ethylene-propylene rubber (EPM), butyl rubber (I
IR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), chlorosulfonated polyethylene (C3M), acrylic rubber (ACM>), urethane rubber (U), silicone rubber (Si), fluororubber (FPM), polysulfide Synthetic rubbers such as rubber (T) and polyether rubber (FOR>) as well as natural rubbers can be used, but styrene-butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR>) are particularly preferred.

Also used as a vulcanizing agent in rubber materials (sulfur,
Zinc oxide, magnesium oxide, organic peroxide, etc. are used. Vulcanization accelerators include thiazole accelerators, sulfenamide accelerators, dithiocarbamate accelerators, aldehyde amine accelerators, guanidine accelerators, thiourea accelerators, xanthate accelerators and thiourea accelerators. agents, aldehyde ammonia type accelerators, etc. are used.

The present invention is characterized in that metal oxide powder is used as a high-temperature fade preventive agent in the friction material. As the metal oxide powder, calcined alumina powder, zinc oxide powder, lead oxide powder, etc. are used, and among these, calcined alumina powder is particularly preferred. Such metal oxide powder preferably has a size of about 150 to 500 meshes, preferably about 250 to 350 meshes. If a metal oxide powder with a size of 150 mesh or more is used, the extruder screw will be easily damaged when extruding the friction material molding composition using an extruder, which is not preferable.

By incorporating metal oxide powder such as calcined alumina into a friction material, the coefficient of friction hardly decreases even when the friction material is used under high temperature conditions, and a friction material having excellent friction properties can be obtained.

For example, in the case of a friction material containing calcined alumina, the friction coefficient μ at 100°C is 0.501 and 20
μ at 0′C is 0.569. On the other hand, when Palite (varium sulfate), which is known as a friction improver for asbestos friction materials, is used as a high-temperature fade preventive agent in the aromatic polyamide fiber-based friction material of the present invention, 1
While the coefficient of friction μ at 00°C is 0.563,
At 200° C., μ decreases significantly to 0.177.

Similarly, when a friction material is manufactured using cashew dust, which is a friction improver for asbestos friction materials, in the present invention, the friction coefficient μ at 100°C is 0.453, but the μ at 200°C is
is greatly reduced to 0.144.

In this way, in the present invention, even if typical compounds such as pallite and cashew dust, which are conventionally used as friction improvers in asbestos friction materials, are used as high-temperature fade preventive agents in friction materials based on aromatic polyamide fibers, It is noteworthy that this is largely ineffective.

Furthermore, the friction material according to the present invention may contain an extender and a thickener, and examples of such extenders and thickeners include bentonite, organically modified bentonite, particulate silica, and carboxymethyl cellulose. .

In the friction material of the present invention, the amount of metal oxide powder as a high-temperature fade inhibitor is 30 to 100 parts by weight, preferably 40 to 80 parts by weight, based on 100 parts by weight of aromatic polyamide fibers as base fibers. used. Further, the binder composition containing a thermosetting resin, a rubber material, and a vulcanizing agent has a molecular weight of 150 to 300% relative to the aromatic polyamide fiber.
Parts by weight are preferably used in amounts of 200 to 250 parts by weight. Furthermore, the amount of extender and filler is 20 to 100 parts by weight, preferably 40 parts by weight, based on the aromatic polyamide fiber.
It is used in an amount of ~80 parts by weight.

Next, a method for manufacturing a friction material according to the present invention will be described, but it is basically the same as the method for manufacturing a friction material made of asbestos, except that asbestos as the base fiber is replaced with aromatic polyamide fiber. Namely, aromatic polyamide fiber, rubber agent,
Thoroughly knead the vulcanizing agent and extender using a roll or kneader. Then, the obtained kneaded product, a solution obtained by dissolving the thermosetting resin in an organic solvent, and a thickener if necessary are thoroughly kneaded, and a high temperature fade preventive agent is added thereto and thoroughly kneaded. A composition for forming a friction material is prepared.

The obtained composition for forming a friction material is supplied to an extrusion molding machine and extrusion molded by the extrusion molding machine to obtain a sheet-like friction material preform.

If this friction material preform is dried and then heated and compressed,
A friction material is obtained.

In the friction material according to the present invention, aromatic polyamide fibers are used as base fibers and metal oxide powder is used as a high-temperature fade preventive agent, so that the following effects can be obtained.

(a> The friction material can be formed from base fibers other than asbestos.

(b) Since extrusion molding is possible, a friction material with excellent mass productivity and excellent cushioning properties and flexibility can be obtained.

(C) Even when used under high-temperature conditions, a friction material can be obtained in which the high-temperature fade phenomenon in which the coefficient of friction decreases is hardly observed.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 100 parts by weight of aromatic polyamide fiber and 10 parts by weight of NBR rubber
0 parts by weight, 10 parts by weight of sulfur, and 150 parts by weight of an extender were thoroughly kneaded with a roll. The obtained kneaded product, a solution of 70 parts by weight of phenolic resin in 150 parts by weight of an organic solvent (acetone), and a thickener, bentone (#27 IND
(manufactured by USTRIES) and 35 parts by weight in a kneader.
After kneading for 0 minutes, 80 parts by weight of 325 mesh calcined alumina powder was added to the mixed wire material and thoroughly kneaded in a kneader to prepare a composition for forming a friction material.

Supplying the obtained friction material forming composition to an extrusion molding machine,
A sheet-like friction material preform was manufactured by extrusion molding using an extrusion molding machine.

After drying the obtained friction material preform at 40 to 80°C, it was dried at a temperature of 180°C and a pressure of 40kof/cm2 for 20 minutes.
A friction material was manufactured by heating and compressing for a minute.

The friction coefficient of the obtained friction material was adjusted to 100°C, 150°C, and 20°C.
Measurements were made at a temperature of 0°C. Further, this friction material was maintained at 200°C, cooled, and heated again to a temperature of 100°C, and the coefficient of friction was measured. The results are shown in Table 1.

A friction material was produced in the same manner as in Example 1, except that cashew dust powder was used instead of calcined alumina powder.

The friction coefficient of this friction material at high temperatures was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A friction material was prepared in the same manner as in Example 1 except that Palite powder was used instead of calcined alumina powder in Example 1. The friction coefficient at high temperature was measured. The results are shown in Table 1.

Table 1 From Table 1, in friction materials based on aromatic polyamide fibers, no high-temperature fade phenomenon is observed when calcined alumina powder is added, whereas in the case of friction materials made of asbestos, the friction improver It can be seen that even when certain cashew dust, pallite, etc. are added to friction materials based on aromatic polyamide fibers, the high-temperature fade phenomenon is not solved at all.

Fuyugo-2 In Example 1, instead of calcined alumina powder, 32
A friction material was produced in the same manner as in Example 1 except that 5 meshes of zinc oxide powder were used.

When we measured the friction coefficient of the obtained friction material at high temperatures, we found that
No high temperature fade phenomenon was observed.

衷凰■ Once in Example 1, instead of the calcined alumina powder, 32
A friction material was produced in the same manner as in Example 1 except that 5 meshes of lead oxide powder were used.

When we measured the friction coefficient of the obtained friction material at high temperatures, we found that
No high temperature fade phenomenon was observed.

Claims (2)

[Claims] (1) It is characterized by comprising an aromatic polyamide fiber as a base material, a binder composition comprising a thermosetting resin and a rubber material, and a metal oxide powder as a high temperature fade preventive agent. extrudable friction material. (2) The extrudable friction material according to claim 1, wherein the metal oxide powder is calcined alumina powder, zinc oxide powder, or lead oxide powder.