JPS6220581A - Frictional material composition for brake lining - Google Patents

Abstract

PURPOSE:A frictional material composition for brake linings, e.g. bicycles, etc., containing glass fibers and pulped aromatic polyamide fibers as base material fibers and a small amount of zircoium oxide powder and having a high friction coefficient with a slight wear ratio. CONSTITUTION:A frictional material composition obtained by incorporating (A) preferably 20-50vol% base material fibers consisting of (i) glass fibers, preferably chopped glass fibers having 5-13mu diameter and 1-6mm length and (ii) pulped aromatic polyamide fibers, preferably a polymer having repeating units containing >=70mol% p-phenylene terephthalamide with (B) preferably 25-65vol% based on the total volume of the composition, organic and inorganic compounding agents containing 0.5-10vol%, based on the total volume of the composition, zirconium oxide powder, preferably having 6-7 Mohs hardness and (C) preferably 15-25vol%, based on the total volume of the composition, phenolic resin binder, preferably consisting essentially of unmodified phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a friction material composition for brake linings of automobiles and the like.

[Prior Art] Conventionally, as a friction material composition for brake lining, an organic friction material having asbestos as a base material and fiber is generally used. In addition, as a fiber base material to replace asbestos, for example, as shown in JP-A-53-130742 and JP-A-56-16579, glass U&fiber, aromatic polyamide fiber, etc. are used. Are known.

[Problems to be solved by the invention] Conventional brake lining compositions using asbestos as a base fiber have known problems such as a relatively small FJ friction coefficient and a fade phenomenon that occurs when the brake is repeatedly depressed. It is being On the other hand, sufficient studies have not been conducted on friction material compositions for brake linings whose base fibers are glass m-fibers or aromatic polyamide fibers.

An object of the present invention is to provide a novel friction material composition for brake linings that has a high coefficient of friction and a low wear rate without using asbestos as a fiber base material.

[Means for Solving the Problems] The II friction material composition for brake linings of the present invention uses glass fibers and pulped aromatic polyamide fibers as the base fibers, and has a composition of 0.5% by volume when the whole is 100% by volume. This is a friction material composition for a resin mold type brake lining, characterized in that it contains zirconium oxide powder of ~10% by volume (hereinafter % indicates volume%).

In the present invention, the resin-molded friction material for brake linings is a molded product made by pressurizing and heat-molding base fibers and organic and inorganic compounding agents using a phenolic resin binder, and is used as a brake lining. It is something that will be done.

The glass fiber constituting the base fiber of the present invention refers to an amorphous inorganic fiber having a fiber diameter of 5 to 13 μm. Note that the glass fiber is preferably chopped glass mH having a length of 1 to 6 mm.

The pulped aromatic polyamide fiber together with the chopped glass fiber constitutes the base fiber. Aromatic polyamide fiber is a polymer made by amide bonding of monomers containing aromatics, and due to the steric hindrance of the atoms that make up the polymer,
A single polymer extends in a straight line, and a fiber is made up of many linear chains of polymers. Typical aromatic polyamide fibers include polyparaphenylene terephthalamide fibers. This polyparaphenylene terephthalamide fiber is a fiber commercially available as Kevlar (registered trademark). Polyparaphenylene terephthalamide refers to a polymer in which 50 mol% or more, more preferably 70 mol% or more of repeating units are paraphenylene terephthalamide. Note that polymetaphenylene isophthalamide fibers are other known aromatic polyamide fibers, but when polymetaphenylene isophthalamide is used as a fiber base material, the fade properties are poor. The pulped aromatic polyamide fiber is obtained by partially grinding the aromatic polyamide fiber itself, and partially splitting and cutting the ma, to form a pulp.

The total base fibers preferably account for 20 to 50% when the entire friction material composition for brake lining is taken as 100%. Further, it is preferable that the glass fiber accounts for 10 to 45% and the pulped aromatic polyamide fiber accounts for 5 to 30%. When the total base fiber content is less than 20%, the coefficient of friction decreases. Conversely, when the total base fiber content exceeds 45%, the amount of wear increases. Moreover, if the glass fiber content is less than 10%, heat resistance will be insufficient. Conversely, if it exceeds 40%, the amount of wear increases.

If the content of pulped aromatic polyamide fiber is less than 5%, wear will increase, and if it exceeds 30%, heat resistance will be insufficient.

The phenolic resin binder refers to a binder mainly composed of a resin obtained by condensing one or more phenols such as phenol and cresol with formaldehyde or a compound that is a source thereof. Modified phenolic resins modified with cashew nut oil, polyvinyl butyral, vegetable oil, melamine, epoxy compounds, etc. may also be used. Note that unmodified phenol resin is preferable in that it is less likely to cause a fade phenomenon.

The blending ratio of the phenolic resin binder is preferably 15 to 25%. If it is less than 15%, the material strength is insufficient, and 25%
If it exceeds 20%, the required porosity of the material cannot be ensured and the fade resistance deteriorates.

Examples of organic and inorganic powder-free agents include graphite,
Friction modifiers such as molybdenum disulfide, lead sulfide, and antimony trisulfide, organic dusts such as cashew dust, metal powders such as copper and sinchu, and inorganic additives such as barium sulfate, magnesium oxide, zirconium oxide, and cryolite are used. . The organic and inorganic powder-free ingredients preferably account for 25 to 65% of the total.

Of this, friction modifier accounts for 5-25%, organic dust accounts for 3-25%.
10%, metal powder 3-10%, inorganic compounding agent 10-40%
degree is preferred.

In the present invention, 0.5 to 10% of zirconium oxide powder is included as an inorganic powder-free agent. This zirconium oxide powder has the effect of significantly improving the friction coefficient of the brake lining when pulped aromatic polyamide fiber is used as the base fiber and phenol resin is used as the binder. In addition,
If the amount of zirconium oxide powder blended is less than 0.5%, the effect of improving the friction coefficient will be small. On the other hand, if it exceeds 10%, the wear of the mating material tends to increase. Note that the zirconium oxide powder is preferably a powder of a mineral having a Mohs hardness of 6 to 8. Zirconium oxide, which has a higher Mohs hardness that is closer to perfect crystals, tends to have higher wear rates.

As a method for manufacturing brake linings using the friction material composition for brake linings of the present invention, a conventional manufacturing method called a molding method can be applied as is. That is, the base fiber, 71-nol resin binder powder, and organic/inorganic compounding agent are sufficiently mixed, placed in a pressure mold, and pressurized at room temperature to preform. This preformed material is then mode-molded using a hot press mold.

[Test Examples] A total of four types of friction material compositions for brake linings were prepared: Example 1, Example 2, and Comparative Example 1 and Comparative Example 2 shown in the table. The glass fiber used as the base fiber in this example has a length of 3 mm and a diameter of about 9 microns. Further, as the pulped aromatic polyamide fiber, commercially available KeVlar (sigma trademark) fiber was partially ground into pulp. Straight phenol resin powder was used as the phenol resin. I'! A mixture of graphite and metal sulfides was used as the rub modifier. Cashew dust was used as the organic dust, and copper powder with a particle size of approximately 500 to 10 μm was used as the metal powder. Barium sulfate, magnesium oxide, magnesium oxide, and zirconium oxide powder having a Mohs hardness of 7 and an average particle size of 8 were not used as inorganic additives. Comparative Example 1 uses lIi! as its inorganic compounding agent. Only 1v barium, magnesium oxide and magnesium oxide were used, no zirconium oxide powder was used. Moreover, in Comparative Example 2, barium sulfate, magnesium oxide, magnesium oxide, and aluminum oxide were used as the inorganic compounding agents, and zirconium oxide powder was not used. Other base fibers, binders, lubricants, organic dust, metal powder, and inorganic compounding agents in Comparative Examples 1 and 2 were the same as in Examples 1 and 2, as shown in the table. The proportions were used.

The brake lining is g+3 as shown in the table for each composition.
and mixed for 10 minutes in a mixer. The resulting mixture was filled into a mold and 300 kg/7 cl was poured at room temperature.
It was preformed by heating for a minute. Next, this preformed body was
Hot pressing was carried out at 5°C for 10 minutes at 300 kg/C1, and after removal from the mold, curing was performed at 250°C for 3 hours.

Each of the obtained brake lining materials was attached to a brake dynamometer and tested. Regarding the coefficient of friction, please refer to JAS
The friction coefficient at a vehicle speed of 100 klll/'hr was determined in the second effectiveness test in the test method specified in O-0406-82. The wear rate was measured as a wear rate by temperature according to the test method of JASo-C427-83. These results are summarized in FIGS. 1 and 2.

FIG. 1 shows the friction coefficient, with the vertical axis showing the friction coefficient and the horizontal axis showing the oil pressure applied to the friction test piece.

The results are shown in Example 1 with a white circle and a solid line, in Example 2 with a black circle and a broken line, in Comparative Example 1 with an X mark and a one-dot broken line, and in Comparative Example 2 with a black triangle and a two-dot broken line. Figure 2 shows the wear rate results, and the vertical axis shows the wear rate (×10'''4 n+m37kg
m) wo, the horizontal axis shows the (1) 7L, r-main temperature before braking. Note that the symbols and types of lines in FIG. 2 are the same as those in FIG. 1.

From FIG. 1, the friction coefficient as a whole tended to become slightly smaller as the oil pressure increased. I
! ! In terms of friction coefficient values, Example 2 had values of 0°52 to 0.45;
Comparative Example 2 is 0.48 to 0.38, Example 1 is 0.45 to
0.34, and Comparative Example 1 had a result of 0°38 to 0.28. Except for Comparative Example 1, the other Examples 2, Comparative Example 2, and σ Example 1 exhibited desirable high coefficients of friction.

From Figure 2, in Comparative Example 2, the brake temperature before braking was 200℃.
Above that, the wear rate suddenly increased. On the other hand, in the case of Example 1, Example 2, and Comparative Example 1, the pre-braking brake temperature was relatively stable and the wear rate was small up to about 250℃, but the wear rate suddenly increased from about 300℃. Indicated.

From the results shown in FIGS. 1 and 2, it was confirmed that the friction coefficients of Examples 1 and 2 were high and the wear rate 9 was low. Furthermore, Comparative Example 1 has a small coefficient of friction. Comparative Example 2 has a high wear rate at temperatures below 250°C. For these reasons, it was confirmed that Comparative Example 1 and Comparative Example 2 were not practical.

[Effects of the Invention] The friction material composition for brake linings containing zirconium oxide as an inorganic compounding agent of the present invention has a relatively high coefficient of friction and a low wear rate, and is highly practical for use in automobiles.

[Brief explanation of drawings]

Figure 1 is a miniature diagram showing the relationship between the friction coefficient of four types of brake linings, including the example, and the oil pressure applied to the friction test piece, and Figure 2 is a miniature diagram showing the relationship between the friction coefficient of four types of brake linings, including the example, and the oil pressure applied to the friction test piece. FIG. Patent applicant: Toyota Motor Corporation Agent
Patent Attorney: Hirotoshi Okawa Patent Attorney: Akio Maruyama Figure 1 Oil Engineering Figure 2 Tere A Temperature before Braking (°C) Procedural Amendment A (Voluntary) July 2, 1985 1, Indication of Case 1985 Patent Application No. No. 158792 No. 2, Name of the invention: SM material composition for brake lining 3, Relationship to the amended case Patent applicant: 1-320 Toyota-cho, Toyota-shi, Aichi Prefecture T-Yota Automobile Co., Ltd. Representative: Kiyoshi Matsumoto 4 , Agent Address: 3-3-4 Meieki, Nakamura-ku, Nagoya, Aichi Prefecture 450, Detailed explanation of the invention in the specification to be amended, column 6, Contents of the amendment (1) Page 8, No. 11 of the specification From the line to the 12th line, [M
The words "magnesium chloride and magnesium oxide" will be corrected to "magnesium oxide and cryolite." (2) The words "magnesium oxide and aluminum oxide" on page 8, lines 14 to 15 of the specification will be corrected to "cryolite and aluminum oxide." (3) In Specification 1, page 8, line 18, the phrase “metal powder and non-silicon compound” should be corrected to “metal powder.” (4) Insert a separate table before the first line of page 8 of the details. 7. Attachment 1 or more of the list of category 1 (1) table

Claims (2)

[Claims] (1) In a resin-molded brake lining friction material composition, the base fiber is composed of glass fiber and pulped aromatic polyamide fiber, and when the total is 100 volume%, the base fiber is 0.5 to 10 volume%. A friction material composition for brake linings containing zirconium oxide powder. (2) The friction material composition for brake linings according to claim 1, wherein the zirconium oxide powder has a Mohs hardness of 6 to 7.