JPH07126407A - Friction material - Google Patents

Abstract

PURPOSE:To provide a friction material excellent in frictional performance at a high temperature and useful for automotive power transmission, etc., by immersing a lead chlorate-adhering fibrous substrate in a mixture containing a friction-controlling agent, etc., forming the immersed fibrous substrate, and subsequently hardening the formed product. CONSTITUTION:A fibrous substrate such as glass fibers to which lead chlorate has adhered is impregnated or mixed with a mixture containing a friction- controlling agent such as calcium carbonate preferably in an amount of 10-60wt.% (based on the friction material) and a binder such as a phenolic resin preferably in an amount of 10-50wt.%, formed and subsequently hardened to produce the objective friction material.

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. Further, 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 can withstand a high load at high temperature, a friction material which has been subjected to a high temperature treatment in advance (for example, JP-A-56-13184).
6, gazette 59-113038 gazette, gazette 60-14.
No. 5302, etc.), but these are associated with high cost and reduced mechanical strength. Those to which a special friction modifier is added (for example, JP-A-60-96625 and 60-92).
No. 332, No. 62-190232, etc.), but the effect cannot be sufficiently exerted because the conventional binder lacks heat resistance and adhesiveness. Also disclosed are those in which aramid fiber or polyimide resin powder with high heat resistance is added to the base material, but the heat resistance of the binder holding the base material and 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 in which the addition amount of a friction modifier has a degree of freedom in order to improve 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]

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 chlorate adhered on its surface, and molding and curing the mixture. ..

In the present invention, the material of the fiber substrate is
Inorganic fiber such as glass fiber, carbon fiber, rock wool, ceramic fiber, metal wire such as iron wire, phenol resin fiber,
There are organic fibers such as aromatic polyamide resin fibers and the like, and there is no particular limitation, but glass fibers are preferable 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 and the friction characteristics can be easily controlled. A more preferable value is 30 to 50% by weight.

The fiber substrate used in the present invention has lead chlorate attached to its surface. As a method of attaching, there is a method of immersing the fiber base material in a solution or dispersion of lead chlorate and then drying to remove the solvent. Examples of the lead chlorate solution or dispersion include an aqueous solution and an aqueous solution in which lead chlorate is dispersed or dissolved in a binder solution, and an aqueous solution is particularly preferably used.

The amount of lead chlorate to be adhered is preferably 5 to 50% by weight with respect to the fiber base material from the viewpoints of the adherence of glass fibers and the like at high temperatures and the 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, fluorite, 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, cashew dust, powders of melamine resin cured products (melamine dusts), rubber dusts, powders of organic resins such as powders of various resin cured products 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 it is preferable to use a phenol resin. The reason is that it has excellent heat resistance and adhesiveness, is inexpensive, and by combining with friction modifiers such as melamine dust, antimony trioxide, and copper powder, it is possible to obtain more friction characteristics than when using other thermosetting resins. 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 substrate (lead-treated substrate) having lead chlorate adhered to its surface is obtained by the above method. Next, in the case where 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) obtained by adding a friction modifier to a binder solution and mixing the mixture, and the mixture is uniformly applied to the base material. After adhering to, the solvent is removed by drying or the like. When the fibrous base material is a short fibrous material, 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 chlorate attached in parentheses]

Example 1 ... 5 (9.03) parts by weight Example 2 ... 10 (18.06) parts by weight Example 3 ... 30 (54.17) parts by weight Comparative Example 1 ... untreated

(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, chemical), calcium carbonate (trade name, manufactured by Takehara Chemical Co., Ltd.) Sunlight SL-1500) 2
0 parts by weight and 40 parts by weight of calcium silicate short fibers (manufactured by NYCO, USA, product name Wollastonite) are mixed as an inorganic powder, 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,
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 blended 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 above friction modifier and the lead nitrate-treated glass fiber base material were added to this resin solution so as to have the compounding ratio shown in Table 2, and a uniform mixture was obtained by 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
15 minutes at ℃, pressure 1.96×10 ⁷ Pa (200kg/cm ² )
Molding was carried out under the conditions described above to obtain a molded product of 5 mm×50 mm×50 mm. After that, 180℃ for 1 hour, 210℃ for 2 hours, 2
Post-curing was performed at 40° C. for 4 hours in this order, and both surfaces of the molded body were ground 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 a friction property test piece. The test piece was mounted on a constant-velocity friction tester defined in JIS D 4411 by pressing at a pressure of 49×10 ⁴ Pa (5 kg/cm ² ) and operated, and the friction coefficient and wear rate at 250° C. and 350° C. (cm ³ /kgf)・M) was measured. The results are shown in Table 3.

[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, but the examples have small wear rates.

[0020]

The friction material of the present invention is a friction material having excellent friction performance at high temperatures.

Claims (1)

[Claims] 1. A friction material obtained by impregnating or mixing a mixture containing a friction modifier and a binder with a fiber base material having lead chlorate adhered to the surface thereof, followed by molding and curing.