JPH0770336A - Friction material - Google Patents

Abstract

PURPOSE:To obtain a friction material excellent in high-temp. friction properties and suitable for an automotive brake, etc., by depositing lead acetate on the surface of a fiber substrate, then impregnating or mixing the substrate with a mixture of a friction modifier and a binder, and molding and curing the resulting product. CONSTITUTION:Lead acetate is deposited on the surface of a fiber substrate such as a glass fiber or a rock wool, e.g. by impregnating the substrate with a lead acetate soln. or dispersion and drying the impregnated substrate. The substrate is then impregnated with a slurrylike mixture contg. a friction modifier such as calcium carbonate or barium sulfate and a binder such as a phenol resin to uniformly deposit the mixture on the substrate, dried to remove the solvent, thermally press-molded with a metal mold, etc., and heat-treated under specified conditions to cure the binder, thus giving a friction material which is asbestos-free and hence pollution-free.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used for power transmission and braking of automobiles.

[0002]

Brake linings, disc pads and clutch facings are generally 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 fibers, carbon fibers, aromatic polyamide fibers, rock wool, ceramic fibers, various steam fibers, etc. have been developed and used as a substitute for asbestos base materials. 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 conventional binder lacks heat resistance and adhesiveness, its effect cannot be fully exhibited. Also, a material such as 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. . Even if a heat resistant resin is used as a binder to obtain a friction material, the conventional manufacturing method is industrially and technically difficult.

Further, there is a friction material produced by a molding method which has a degree of freedom in the addition amount of a friction modifier for improving friction characteristics, but since short fibers are used as a fiber base material, there is a problem in fiber strength. Yes, commercialization is limited to a small part.

The present invention solves the above problems and provides a friction material having stable friction characteristics even under high temperature and high load conditions.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a friction material obtained by impregnating or mixing a mixture containing a friction modifier and a binder into a fiber base material having lead acetate adhered to the surface thereof, followed by molding and curing.

In the present invention, as the material of the fiber base material,
Inorganic fiber such as glass fiber, carbon fiber, rock wool, ceramic fiber, metal wire such as iron wire, phenol resin fiber,
Organic fibers such as aromatic polyamide resin fibers are available, and there is no particular limitation, but glass fibers are preferred because they are easy to process and inexpensive. Examples of the shape of the fibrous base material include non-woven fabrics such as mats and felts, sheet-like base materials such as papermaking sheets and woven fabrics, short fibrous base materials, and string-like base materials such as twisted yarns. It is preferable that the fibrous base material is contained in the friction material in an amount of 25 to 60% by weight because the friction characteristics are well balanced. A more preferable value is 30 to 50% by weight.

Lead acetate is attached to the surface of the fiber base material used in the present invention. As a method of attaching, there is a method of immersing the fiber base material in a solution or dispersion of lead acetate and then drying it to remove the solvent. As a solution or dispersion of lead acetate,
Examples of the binder solution include lead acetate dispersed or dissolved and an aqueous solution, and it is particularly preferable to use an aqueous solution.

The amount of lead acetate to be adhered is preferably 5 to 50% by weight with respect to the fiber base material, from the viewpoints of adhesion of glass fibers and the like at high temperatures and friction characteristics at high temperatures.
It is more preferably 10 to 30% by weight.

Friction modifiers include calcium carbonate, calcium silicate, magnesium carbonate, barium sulfate, clay, talc, graphite, carbon black, alumina, mica, fluorspar, zirconia, hematite, magnetite, silica, antimony sulfide, trioxide. Various inorganic powders such as antimony, iron sulfide, molybdenum sulfide and short fibers, copper,
Powders of metals such as iron and lead, powders of cashew dust, powders of melamine resin cured products (melamine dusts), rubber dusts, powders of various resin cured products, and the like are used. The friction modifier is preferably contained in the resulting friction material in an amount of 10 to 60% by weight because a stable friction coefficient is obtained and the balance with the wear amount is excellent. It is more preferably 20 to 40% by weight.

As the binder, various thermosetting resins can be mentioned, but a phenol resin is preferably used. The reason is that it has excellent heat resistance and adhesiveness, is inexpensive, and combines with friction modifiers such as melamine dust, antimony trioxide, copper powder, etc. This is because the temperature dependence can be reduced. Among the phenolic resins, unmodified and resol type resins are more preferable. Further, a thermosetting resin such as a melamine resin, a urea resin, a polyamideimide resin, a polyimide resin, an epoxy resin or a crosslinkable rubber may be used together with the phenol resin to the extent that the heat resistance is not affected. The binder is preferably contained in the obtained friction material in a solid content of 10 to 50% by weight because the binding force between the fiber base material and the friction modifier is excellent and the friction coefficient and the wear rate can be easily adjusted.

A method for obtaining a friction material using the above materials will be described. First, a fiber base material (lead-treated base material) having lead acetate adhered to the surface thereof is obtained by the above method. Next, when the fiber base material is in the form of a string or a sheet, the lead-treated base material is impregnated with a mixture (slurry) prepared by adding a friction modifier to a binder solution and mixing the mixture, and the mixture is uniformly applied to the base material. The solvent is removed by drying or the like. When the fibrous base material is short fibrous, the friction modifier and the lead-treated base material are mixed with the binder solution to form a uniform mixture with a kneader or the like, and the solvent is removed by drying or the like. Next, it is placed in a mold or the like and subjected to thermocompression molding, and then the molded product is heat-treated under predetermined heating conditions to cure the binder and obtain a friction material.

[0013]

[Amount of lead attached to 100 parts by weight of glass fiber, amount of lead acetate attached in parentheses]

 Example 1 ... 5 (7.9) parts by weight Example 2 ... 10 (15.7) parts by weight Example 3 ... 30 (47.1) parts by weight Comparative Example 1 ..... processing

(2) Preparation of Friction Modifier 20 parts by weight of barium sulfate (manufactured by Sakai Chemical Co., BC), 20 parts by weight of talc (manufactured by Wako Pure Chemical Industries, Ltd.), calcium carbonate (trade name, manufactured by Takehara Chemical Co., Ltd.) Sunlight SL-1500) 2
Inorganic powder in which 0 part by weight and 40 parts by weight of calcium silicate short fiber (manufactured by NYCO, Inc., trade name Wollastonite) are mixed, methylated melamine resin (manufactured by Nippon Carbide,
S-260) at 150 ° C. for 1 hour, 180 ° C. for 4 hours,
Next, melamine dust, iron oxide (Fe ₂ O ₃ ) powder (manufactured by Wako Pure Chemical Industries, manufactured by Wako Pure Chemical Industries, Ltd.,
For chemistry, average particle size: 50-100 μm) and copper powder (made by Wako Pure Chemical Industries, copper foil powder for chemistry, average thickness 2 μm, minor axis 5)
0 μm, major axis 70 μm) were mixed at the weight ratios shown in Table 1 and mixed by a V-type mixer to prepare a friction modifier.

[0015]

[Table 1]

(3) Production of friction material A resin solution prepared by dissolving 15 parts by weight of a phenol resin (TD-2040C, manufactured by Dainippon Ink and Chemicals, Inc., solid content 100% by weight) as a binder solution in 85 parts by weight of methyl ethyl ketone (MEK). (Solid content 15% by weight) was used. The friction modifier and the lead acetate-treated glass fiber base material were added to this resin solution at the compounding ratio shown in Table 2 to obtain a uniform mixture with a kneader. This admixture was dried at 60 ° C. for 2 hours to give a molding admixture, which was then filled into a mold, 160
Formed at pressure of 200kg / cm ² for 15 minutes at ℃ 5mm × 50mm ×
A 50 mm compact was obtained. After that, at 180 ℃ for 1 hour, 2
Post-curing was carried out in the order of 10 ° C. for 2 hours and 240 ° C. for 4 hours, and both surfaces of the molded body were polished with a sander to obtain a friction material.

[0017]

[Table 2]

The friction materials obtained in Examples and Comparative Examples were used as 25
It was cut into mm squares to obtain friction property test pieces. This test piece was mounted on a constant speed friction tester specified in JIS D 4411 by pressing at a pressure of 5 kg / cm ² and operated at 250 ° C. and 3
The friction coefficient and wear rate (cm ³ / kgf · m) at 50 ° C. were measured. The results are shown in Table 3.

[0019]

[Table 3] As is clear from Table 2, the comparative examples have large wear rates at high temperatures and are inferior in friction performance. On the other hand, the wear rate of the example is small.

[0020]

The friction material of the present invention has excellent friction performance at high temperatures.

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[Procedure amendment]

[Submission date] November 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

Brake linings, disc pads and clutch facings are generally 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. Currently, as an alternative material for asbestos substrate, glass fibers, carbon fibers, aromatic polyamide fibers, rock wool, ceramic fiber, various kinds of friction material using a steam le full <br/> Aiba, etc. have been developed, with some It is used. 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.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

(3) Production of friction material A resin solution prepared by dissolving 15 parts by weight of a phenol resin (TD-2040C, manufactured by Dainippon Ink and Chemicals, Inc., solid content 100% by weight) as a binder solution in 85 parts by weight of methyl ethyl ketone (MEK). (Solid content 15% by weight) was used. The friction modifier and the lead acetate-treated glass fiber base material were added to this resin solution at the compounding ratio shown in Table 2 to obtain a uniform mixture with a kneader. This admixture was dried at 60 ° C. for 2 hours to give a molding admixture, which was then filled into a mold, 160
Formed at pressure of 200kg / cm ² for 15 minutes at ℃ 5mm × 50mm ×
A 50 mm compact was obtained. After that, at 180 ℃ for 1 hour, 2
2 hours at 10 ° C., subjected to post curing in the order of 4 hours at 240 ° C., and Migaku Ken the molded body sided Thunder, to obtain a friction material.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

[Table 3] As is clear from Table 3 , the comparative examples have large wear rates at high temperatures and are inferior in friction performance. On the other hand, the wear rate of the example is small.

Claims (1)

[Claims] 1. A fiber base material having lead acetate adhered to its surface,
Impregnating or mixing an admixture containing a friction modifier and a binder,
Friction material that is formed and cured.