JPH073040A - Production of friction material - Google Patents

Abstract

PURPOSE:To obtain a method for producing a friction material in which the friction material having a stable friction coefficient and a low wear rate even under conditions of a high temperature and load can be produced. CONSTITUTION:This method for producing a friction material is to knead or impregnate (d) a substrate composed of a fibrous material with a composition for the friction material containing (a) 20-70 pts.wt. binder, (b) 30-80 pts.wt. friction modifier [with the proviso that the total amount of the components (a) and (b) is regulated to 100 pts.wt.] and (c) carbon black in an amount of 15-50 pts.wt. based on 100 pts.wt. total amount of the components (a) and (b), then dry the kneaded or impregnated substrate, preform the dried kneaded or impregnated substrate, hot press form the preformed substrate, further heat- treat the hot press formed substrate at 230-330 deg.C for 1-8hr and subsequently cure the heat-treated substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a friction material used for power transmission, braking, etc. of an automobile.

[0002]

Brake linings, disc pads, clutch facings and the like are used as friction materials for automobiles. Conventionally, asbestos (asbestos) has been used as a base material, but development of a non-asbestos friction material is desired due to the problem of asbestos pollution. Further, as the performance of automobile engines is improved, it is desired to improve the friction characteristics (friction coefficient, wear rate) and mechanical characteristics of friction materials. Furthermore, recently, the usage conditions have become severe, and high-speed rotation strength at high temperatures has been required. At present, friction materials using glass fiber, carbon fiber, aromatic polyamide fiber, rock wool, ceramic fiber, various steel fibers, etc. have been developed and used as a substitute for the asbestos base material. However, since these base materials have higher elasticity and hardness and lower heat resistance than conventional asbestos, there are various problems when used as a friction material, and the above-mentioned required performance is not satisfied.

[0003]

As a friction material which uses an asbestos substitute material and withstands a high load at a high temperature, the friction material itself is preliminarily treated at a high temperature (for example, JP-A-56-13184).
6, gazette 59-113038 gazette, gazette 60-14.
No. 5302, etc.), but this involves a high cost and a decrease in mechanical strength. Those to which a special friction modifier is added (for example, JP-A-60-96625 and JP-A-60-9233).
No. 2, gazette, No. 62-190232, etc.),
Since the heat resistance and adhesiveness of the binder are insufficient, the effect cannot be fully exerted. Also disclosed are those in which aramid fiber or polyimide resin powder having high heat resistance is added to the base material, but the heat resistance of the binder holding the base material and the friction modifier is not sufficient and high temperature strength cannot be obtained. . In addition, in order to improve the frictional characteristics, it is made to be porous and lightweight, and short glass fibers are twisted and spun into a spun glass string, or an acrylic fiber is added to this glass string.
A mixed spun glass string is used in which fibers such as fiber, rayon, aromatic polyamide and phenol resin are mixed.
There are problems such as high price and various adverse effects on friction characteristics at high temperatures, and commercialization is limited to a part.

An object of the present invention is to solve the above problems and provide a friction material having stable friction characteristics even under high temperature and high load conditions.

[0005]

According to the present invention, (a) the binder is 20 to 70 parts by weight and (b) the friction modifier is 30 to 80 parts by weight (however, the total amount of (a) and (b) is 100 parts by weight). And (a) and (b) in a total amount of 100 parts by weight, (c) a composition for a friction material comprising 15 to 50 parts by weight of carbon black, and (d) a fibrous substance. A method for producing a friction material, comprising: kneading or impregnating a base material, drying, preforming, hot-pressing, and further heat-treating at 230 to 330 ° C. for 1 to 8 hours for post-curing. Regarding

(A) The binder is not particularly limited,
Known materials can be used, for example, thermosetting resins such as phenol resin, melamine resin, urea resin, epoxy resin, polyamideimide precursor resin, polyimide precursor resin, natural rubber, chloroprene rubber, styrene butadiene rubber. And rubber such as acrylonitrile butadiene rubber and acrylic rubber. Among these, a phenol resin and a melamine resin are preferable from the viewpoint of the balance of properties, and among them, a resol type phenol resin and a methylated melamine resin are more preferable. Further, rubber is preferable from the viewpoint of improving heat resistance. When rubber is used, a rubber crosslinking agent such as sulfur may be used if necessary.

The friction modifier (b) is not particularly limited, and known ones can be used. Examples thereof include calcium carbonate, magnesium carbonate, barium sulfate, calcium silicate short fiber, clay, talc, graphite, alumina,
Inorganic powder of mica, fluorite, zirconia, hematite, magnetite, silica, antimony sulfide, lead sulfide, iron sulfide, zinc sulfide, molybdenum sulfide, antimony trioxide, etc., metal powder of iron, lead, copper, etc., cashew dust , Powders of organic substances such as powders of cured products of thermosetting resins such as melamine resins. These are used alone or in combination of two or more.

As the carbon black (c), known carbon black can be used without particular limitation.

The component (a) is in the range of 20 to 70 parts by weight, and the component (b) is in the range of 30 to 80 parts by weight (however,
(The total amount of (a) and (b) is 100 parts by weight). Further, the component (c) is 15 to 50 parts by weight (preferably 20 to 45 parts by weight, more preferably 35) based on 100 parts by weight of the total amount of the components (a) and (b).
Up to 45 parts by weight).

If the amount of component (a) is too small, the mechanical strength will be poor, and if it is too large, the friction coefficient and the amount of wear cannot be balanced. If the amount of component (b) is too small, the friction coefficient becomes unstable and the amount of wear increases, and if it is too large, the friction coefficient and the amount of wear cannot be balanced. If the amount of the component (c) is too small, the heat resistance is lowered and the friction characteristics at high temperature are deteriorated, and if it is too large, the friction coefficient becomes unstable and the amount of wear increases.

In addition to the above (a), (b) and (c), the resin composition for a friction material of the present invention may further contain other components such as water, methyl ethyl ketone, toluene, etc. Dispersants such as organic solvents, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, carboxyethyl cellulose, polyvinylpyrrolidone, polyvinyl alcohol, styrene-maleic acid copolymers,
Examples thereof include additives such as plasticizers such as ethylene glycol, propylene glycol, dimethyl phthalate, surfactants, adhesion improvers and the like. The composition for friction material can be manufactured, for example, as follows. (A) Binder, (b) friction modifier, (c) carbon black, and other components used as necessary may be well mixed with a high-speed mixer or the like to obtain a slurry-like composition for friction material. it can.

The friction material can be obtained, for example, as follows. The composition for a friction material is kneaded or impregnated into a base material made of (d) a fibrous substance, and (d) a kneaded product of the base material made of a fibrous material and the composition for a friction material or (d) a fibrous material. A friction material composition is uniformly impregnated and coated on a base material made of to obtain a coated cord, and the kneaded product or the coated cord is dried to remove the solvent and preform. Then put it in a mold etc. and hot press molding (140-180 ° C, 50-150 kgf / cm ² , 5-3
0 minutes) to obtain a molded product, and this molded product is 230 to 330
A heat treatment is performed at a temperature of 1 to 8 hours for post-curing to obtain a friction material. If the heat treatment temperature and time are out of this range, the productivity, workability, frictional properties (especially at high temperature) and mechanical strength will be poor.

As the base material composed of the above-mentioned (e) fibrous substance, known materials can be used without particular limitation, and examples thereof include glass fiber, carbon fiber, rock wool,
Inorganic fibers such as ceramic fibers, metal wires such as iron wires, organic fibers such as phenol resin fibers, aromatic polyamide resin fibers, and the like can be mentioned, and glass fibers are preferable because they are easy to process and inexpensive. The form of the base material made of a fibrous substance includes, but is not limited to, non-woven fabrics such as chops, filaments, rovings, twisted yarns, yarns, mats and felts, paper sheets, and woven fabrics.

(E) The base material composed of the fibrous material has a weight ratio of the friction material finally obtained such that the composition of the base material composed of the fibrous material / the friction material composition (solid content) is from 30/70.
It is preferably used in an amount such that it is in the range of 70/30. If the amount of the base material made of a fibrous substance is too small, the mechanical strength of the friction material tends to decrease, and if it is too large, the friction characteristics become unstable and wear increases, and the mechanical strength changes due to the change of friction with time. Tends to decline. In the base material / friction material composition (solid content) made of a fibrous material in the above-mentioned weight ratio, the weight of the friction material composition (solid content) is per unit of the finally obtained friction material. Can be confirmed as a value A-B obtained by subtracting the weight B of the base material made of the fibrous substance per unit from this. The fine adjustment of the weight ratio can be easily performed by increasing or decreasing the solid content concentration of the friction material composition, increasing or decreasing the impregnation coating speed, and the like.

[0015]

EXAMPLES The present invention will now be described with reference to examples. Barium sulfate (Sakai Chemical Co., BC), talc (Wako Pure Chemical Industries, chemical), calcium carbonate (Takehara Chemical Co., trade name Sunlight SL-1500), calcium silicate short fiber (US NYCO, Brand name Wollastonite) 40 parts by weight of inorganic powder and copper powder (Wako Pure Chemical Industries, copper foil powder for chemicals, average thickness 2 μm, minor axis 50 μm, major axis 70)
μm) and a carbon black (Mitsubishi Kasei # 44 carbon black) were mixed at a ratio shown in Table 1 to obtain a mixture. In addition, NBR (Nihon Zeon, Ni
15 parts by weight of pool 1041) was dissolved in 85 parts by weight of methyl ethyl ketone (MEK) to obtain a solution of rubber as a binder having a solid content of 15% by weight. In addition, phenol resin (manufactured by Dainippon Ink and Chemicals, TD-2040C, solid content 10
0%) 15 parts by weight of methyl ethyl ketone (MEK) 85
A thermosetting resin solution as a binder having a solid content of 15% by weight was obtained by dissolving in parts by weight. A solution of the binder was added to the mixture of the friction modifier and carbon black in the proportions shown in Table 1 and kneaded to obtain a slurry-like composition for the friction material.

[0016]

[Table 1]

In addition, chopped glass fiber (made by Fuji Fiber Glass, UPG IZA508, length about 30 m
The m) was disentangled (opened) with a mixer to obtain a substrate made of a fibrous substance.

Examples 1 and 2 67 parts by weight of the fibrous base material was added to 100 parts by weight of the friction material composition (solid content) and kneaded with a kneader to obtain a kneaded product. ME for 2 hours at ℃
Remove K and preform, then fill it in a mold,
Molding was carried out at 160 ° C. for 15 minutes at a pressure of 100 kgf / cm ² to obtain a molded body of 5 mm thickness × 50 mm square. Then, post-curing was performed in the order of 230 ° C. for 1 hour and 260 ° C. for 4 hours, and both surfaces were polished with a sander to obtain a friction material.

Comparative Examples 1 and 2 The materials were blended and mixed according to the formulation of Table 1, and the other components were used in Example 1.
A friction material was obtained in the same manner as in.

The friction materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were cut into 25 mm square pieces to prepare test pieces for evaluating friction characteristics. This test piece was attached to a low-speed friction tester specified in JIS D4411, operated at a pressing pressure of 5 kgf / cm ² , and the friction coefficient and wear rate (cm ³ / kgf-m) at 150 ° C, 250 ° C and 350 ° C were measured. did. The results are shown in Table 2.

[0021]

[Table 2]

From Table 2, Comparative Examples 1 and 2 have large fluctuations in the friction coefficient at each temperature, high wear rates at high temperatures, and poor friction characteristics. On the other hand, Examples 1 and 2 have stable friction coefficient and excellent friction characteristics with a small wear rate.

[0023]

According to the present invention, a friction material having good friction characteristics at high temperatures can be obtained.

Claims (1)

[Claims] 1. (a) 20 to 70 parts by weight of a binder and (b) 30 to 80 parts by weight of a friction modifier (provided that the total amount of (a) and (b) is 100 parts by weight) and ( The friction material composition containing (c) 15 to 50 parts by weight of carbon black is kneaded or impregnated into a base material made of a fibrous substance with respect to 100 parts by weight of the total of (a) and (b). A method for producing a friction material, which comprises: drying, preforming, hot-pressing, and heat-treating at 230 to 330 ° C. for 1 to 8 hours for post-curing.