JPH11116697A - Nonasbetos-based friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonasbestos-based friction material, improved in friction coefficient and abrasion resistance and used for a brake device or the like of automobiles or the like. SOLUTION: This nonasbestos-based friction material is obtained by compounding a powder of a hollandite type octotitanate represented by the following formula Kx Bay Mg(x+2y)/2 Ti8-(x+2y)/2 O16 [(x) is 0.2-1.4; (y) is 0.2-1.4] as a substrate in the friction material prepared by binding and molding a mixture containing the substrate, a filter or the like with a thermosetting resin as a binder. The amount of the compounded powder of the octotitanate is preferably within the range of about 3-50 wt.%. Adequate amounts of various friction modifiers (barium sulfate or the like), other additives (a rust preventing agent or the like) are further compounded therein.

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 a brake lining, a disk pad, a clutch facing and the like of a braking device of an automobile, a railway vehicle, an aircraft, an industrial machine and the like.

[0002]

2. Description of the Related Art A friction material of the above braking device is formed by binding a mixture of a thermosetting resin resin (a phenol resin, an epoxy resin, etc.) and a base fiber, a filler, etc. under heat and pressure. It is manufactured by doing. Conventionally, friction materials containing asbestos fibers have been used as the base material, but this material has a relatively low friction coefficient in the low and high temperature regions, and the friction coefficient increases rapidly with the increase in the friction surface in particular. A fading phenomenon that tends to decrease tends to occur. It has also been pointed out that the use of asbestos fiber is carcinogenic. As a countermeasure, potassium hexatitanate (K
₂ Ti ₆ O ₁₃ alkali metal titanate compound represented _{by) (M 2 Ti n O 2n} + 1, M: an attempt has been made for practical use of non-asbestos friction material powder was compounded of an alkali metal).

[0003]

In order to meet the demands for miniaturization and weight reduction of automobile brake devices, a friction material capable of stably maintaining a high coefficient of friction in a wide temperature range is required.
The alkali metal hexatitanate powder has strength, heat resistance,
It has excellent wear resistance and reinforcing properties, and can provide a friction material with friction and wear characteristics that cannot be obtained with asbestos fibers.
However, there is still room for improvement in fade resistance, friction coefficient, and the like in a high temperature range. The present invention has been made in view of the above, and has a non-asbestos-based friction material that stably maintains a high friction coefficient over a wide temperature range from a low temperature to a high temperature, and has good abrasion resistance and aggressiveness to a mating material. Is provided.

[0004]

SUMMARY OF THE INVENTION The friction material of the present invention is a non-asbestos-based friction material obtained by binding-forming a mixture containing a thermosetting resin, a thermosetting resin as a binder, and a base material, a filler and the like. in the friction material, as the base material, the following _{formula: K x Ba y Mg (x} + 2y) / 2 Ti 8- (x + 2y) / 2 O 16 wherein, x = 0.2 to 1.4, y = 0.2-1.4], and is characterized by containing an octotitanate powder having a hollandite-type crystal structure represented by the following formula:

[0005] The octotitanate having the hollandite structure has a structure of (Ti, Mg) O ₆ octahedron in which K ⁺ ,
It is a compound having a one-dimensional tunnel type crystal structure coordinated with Ba ⁺⁺ ion. This has a high melting point (about 1450 ° C. or more), excellent heat resistance and reinforcing effect, and has a hardness of about 5 to 6 in Mohs hardness, which is an appropriate hardness as a friction material. In actual use of a friction material such as a brake pad for an automobile, it is estimated that the friction surface locally rises in temperature to 1000 ° C. or more due to the generation and heat storage of friction heat. By blending the above octotitanate powder as a base material of the friction material exposed to the harsh use conditions, an excellent high coefficient of friction and abrasion resistance in a high temperature range are ensured, and its temperature dependency is high. It is small and stably maintained over a wide temperature range from low to high.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The shape of octotitanate is not particularly limited, but the major axis is about 10 to 100 μm and the minor axis is about 3
Particles having a particle form of about 20 to 20 [mu] m and an aspect ratio of about 2 to 5 are preferable in that the uniformity of kneading and dispersion in the resin is good and the reinforcing effect is excellent. The proportion of the octotitanate powder in the friction material is suitably in the range of 3 to 50% by weight. If the amount is less than 3% by weight, the effect of the compounding is small, while if the amount is more than 50% by weight, the effect of improving the friction and wear characteristics is saturated, and there is no advantage of further increasing the amount.

[0007] The raw material composition of the friction material of the present invention is not different from the conventional non-asbestos-based friction material except that the above-mentioned octotitanate powder is blended. No restrictions are imposed. As the binding component, for example, a thermosetting resin such as a phenol resin, an epoxy resin, or a silicone resin, or a modified resin thereof (modified with cashew oil, modified with dryness, modified with rubber, or the like) is appropriately used.

Further, as the base material, together with the above octotitanate, known materials as the base material of the friction material, for example, organic fibers such as polyamide fiber, aramid fiber and phenol fiber, ceramic fiber, glass fiber, and synthetic inorganic compound. One or more of inorganic fibers such as fibers (potassium titanate fibers), metal fibers such as steel fibers, and non-ferrous metal fibers (brass, copper, aluminum, etc.) are appropriately blended. The base material is subjected to a coupling treatment with a silane-based coupling agent or a titanate-based coupling agent according to a conventional method, which is performed as a surface treatment for enhancing dispersibility and binding with a resin binder, if desired. Is used.

Fillers include natural or synthetic rubber powders, vulcanized or unvulcanized, organic powders such as cashew resin powder, resin dust, rubber dust, graphite, molybdenum disulfide, antimony trisulfide, barium sulfate, calcium carbonate, etc. Two or more powders such as inorganic powders, metal powders such as copper, aluminum, zinc, and iron, and oxide powders such as alumina, silica, chromium oxide, copper oxide, titanium oxide, iron oxide, and zircon. An appropriate amount is blended. In addition, the addition of an appropriate amount of a rust preventive, a lubricant, a grinding agent, or the like as necessary does not differ from that of a normal friction material.

[0010] After the above-mentioned raw material composition is preformed, it is subjected to binding under heat and pressure (pressure: about 10 to 40 MPa, temperature: about 150 to 200 ° C). After being removed from the mold, heat-treat as necessary (temperature: approx.
200 ° C., holding time: about 1 to 12 hours), and then machined and polished to finish the desired friction material.

[0011]

【Example】

[1] Production of friction material (1) Raw material composition Base material (octotitanate powder) 30% by weight Binder (phenol resin) 20% by weight Friction modifier (barium sulfate) 50% by weight The above octotitanate powder Is the powder (K _0.7
Ba _0.7 Mg _1.05 Ti _6.95 O ₁₆ ) was used.

(2) Forming After the raw material composition is preformed (pressing force: 14.7 MPa, temperature: normal temperature, time: 1 minute), it is bound and formed by a die (pressing force: 14.7 MPa, temperature: 170). ℃, pressure holding time: 5
Min), after molding, demolding and heat treatment in a drying oven (180
C. for 3 hours). After that, it is cut to a predetermined size and polished to obtain a test friction material (disk pad).
This sample friction material is designated as A.

(Comparative Example 1) A test friction was obtained by the same raw material composition and molding process as in the above example except that asbestos fibers (6 classes) were used instead of the octotitanate powder as the base material. Get the material. This is designated as friction material B. (Comparative Example 2) As a substrate, potassium hexatitanate fiber [fiber diameter (average) about 30 µm instead of octotitanate powder]
m, a fiber length (average) of about 150 μm] is used, and a test friction material is obtained by the same raw material composition and molding process as in the above example. This is designated as friction material C.

[Friction and Wear Test] The friction coefficient and specific wear rate (cm ³ / N · m) of each of the above-mentioned friction materials were determined by a constant speed friction and wear test specified in JIS D4411 “Brake lining for automobiles”. Measure. 1 and 2 show the test results.
(FIG. 1: friction coefficient, FIG. 2: specific wear rate). Disc friction surface: FC25 gray cast iron, surface pressure: 10Kgf / c
m ^2, friction speed: 7m / sec.

FIG. 1 (coefficient of friction) and FIG. 2 (specific wear rate)
As shown in the above, friction material B (using asbestos fiber)
Low coefficient of friction at low and high temperatures, especially at 350 ° C
The drop in the high-temperature region exceeding the temperature is sharp, and the decrease in wear resistance in the high-temperature region is also remarkable. Friction material C (using potassium hexatitanate fiber) also has a low friction coefficient in a low temperature range. On the other hand, the friction material A of the invention example has a high friction coefficient, its temperature dependency is small, the high friction coefficient is stably maintained in a wide temperature range from low to high temperature, and the wear resistance is also high. Needless to say, in the low temperature range, the increase in the wear amount in the high temperature range exceeding 300 ° C. is small, and the effect of improving the friction and wear characteristics is remarkable.

[0016]

[Reference example]

[Production of hollandite-type octotitanate powder] (1) Titanium oxide (anatase type), potassium carbonate, barium carbonate, and magnesium carbonate are converted into TiO ₂ / K ₂ O / BaO
/ MgO = 6.95 / 0.35 / 0.7 / 1.05 (molar ratio). After adding 5% by weight of water to the mixed powder, press molding (pressure of 5.1 MPa) is performed to obtain a compact. (2) The molded body is heated and held at 1350 ° C. for 3 hours to perform a baking treatment, and then cooled in a furnace. The sintering anti-product is a lump solidified with octotitanate. (3) The fired reaction product is coarsely pulverized, passed through a 2 mm sieve, water is added, and the mixture is agitated with a household mixer for 10 minutes to be defibrated. After defibration, dehydrate and dry. Composition (X-ray powder diffraction): K _0.7 Ba _0.7 Mg _1.05 Ti
_6.95 O ₁₆ size (scanning electron microscope): major axis 10-50μm, minor axis 3
-20 μm, aspect ratio 2-3.

[0017]

The friction material of the present invention has a high coefficient of friction and outstanding wear resistance, its temperature dependence of its friction and wear characteristics is small, and is stably maintained in a wide temperature range from low to high temperatures. Therefore, the friction material of the present invention can be used for automobiles,
It is useful as a brake lining, clutch facing, disc pad, etc. for braking devices such as vehicles, aircraft, industrial machinery, etc., and can respond to higher speeds, smaller and lighter braking devices, and improved braking functions. -It has effects such as stabilization and improved durability.

[Brief description of the drawings]

FIG. 1 is a graph showing a measurement result of a friction coefficient by a constant speed friction and wear test.

FIG. 2 is a graph showing a measurement result of a specific wear rate by a constant speed friction wear test.

Claims (1)

[Claims] 1. A non-asbestos-based friction material obtained by binding and molding a mixture containing a thermosetting resin, a thermosetting resin as a binder, and a base material, a filler, and the like. _{K x Ba y Mg (x +} 2y) / 2 Ti 8- (x + 2y) / 2 O 16 wherein, x = 0.2~1.4, y = 0.2~1.4] represented by A non-asbestos-based friction material comprising octotitanate powder having a hollandite-type crystal structure.