JPH08337660A - Friction material - Google Patents

Abstract

PURPOSE: To obtain a friction material which can stably retain high-temp. friction characteristics by compounding a composite titanium compd. powder comprising crystal particles of a specific alkaline earth metal titanate and crystal particles of a specific alkali metal titanate as the base material into a binder resin. CONSTITUTION: A raw material mixture comprising TiO2 , RO (wherein R is an alkalne earth metal), and M2 O (wherein M is an alkali metal) in a molar ratio satisfying the relation: Z>=X+nY (wherein X is the number of moles of RO; Y is the number of moles of M2 O; Z is the number of moles of TiO2 ; and n is 2-6) is baked at 700-1,300 deg.C to give a composite titanium compd. powder comprising crystal particles of an alkaline earth metal titanate represented by RTiO3 and crystal particles of an alkali metal titanate represented by M2 Tin O2n+1 . The powder as the base material is dispersed in a binder resin, and the resulting dispersion is mixed homogeneously with required amts. of a friction and abrasion modifier, a rust preventive, a lubricant, an abrasive, etc., premolded and then molded under heating and pressure e.g. in a mold, and machined and ground to give a finished friction material with a desired shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material constituting a sliding surface such as a brake lining, a disc pad, a clutch facing, etc. in a braking device for automobiles, railway vehicles, aircrafts, industrial machines and the like.

[0002]

2. Description of the Related Art The friction material of the above braking device is made of resin (phenotype).
Resin, epoxy resin, etc.) as a binder
And a friction / wear modifier (sulfate
The mixture with the mixture) is bound and formed under heat and pressure.
It is manufactured by Conventionally asbestos as a base material
Although fibers have been used, the friction material is
Wear damage significantly increases as
Sudden drop and fade phenomenon are likely to occur. Asbestos
Carcinogenic problems have also been pointed out in the fibers. For this reason,
Asbestos alternatives are being developed,
M₂Ti_nO_{2n + 1}[In the formula, M is K, Na, Li, Rb, etc.
Alkali metal, n = 2-6]
Potassium metal fiber (typically potassium hexatitanate fiber (K
₂Ti₆O ₁₃)], Or alumina / silica fiber, etc.
Practical application of blended friction materials has been tried (for example,
Japanese Unexamined Patent Publication No. 61-191599, Japanese Patent Laid-Open No. 1-29455.
No. 3, etc.).

[0003]

In order to meet the demands for downsizing and weight reduction of automobile brake devices, a friction material having a high coefficient of friction and capable of stably maintaining a high coefficient of friction in a wide temperature range is required. Required. The alkali metal titanate fiber such as the potassium hexatitanate fiber is a material having excellent strength, strength, heat resistance, wear resistance, reinforcing property and the like, and having an appropriate hardness as a friction material. The manufactured friction material exhibits friction and wear characteristics superior to those of conventional friction materials using asbestos fibers. However, it cannot be said that the anti-fade property and the friction coefficient in the high temperature range (about 300 ° C. or higher) are sufficient. It has also been proposed to compound potassium titanate fiber and alumina / silica fiber in combination for the purpose of further enhancing the fade resistance property. As a result, the aggressiveness of the opponent material becomes stronger. The present invention aims to solve the problems associated with conventional friction materials and to provide a friction material that can stably maintain friction characteristics in a high temperature range.

[0004]

The friction material of the present invention is a friction material obtained by binding and molding a mixture of a resin and a base material, wherein the base material is RTiO ₃ [where R is an alkaline earth metal]. and the crystal grains of the titanate alkaline earth metal represented by metal] in M ₂ Ti _n O _{2n + 1} [wherein, M is an alkali metal, n represents the crystalline alkali metal titanate represented by 2-6] It is characterized in that grains or a composite titanium compound powder composed of these grains and titania (TiO ₂ ) grains is mixed.

[0005]

[Function] Alkaline earth metal titanate [RTiO ₃ ] (R
(Mg, Ca, Sr, Ba, etc.) is a compound having a perovskite type crystal structure. This compound has excellent strength, heat resistance, heat insulation, wear resistance and the like, and has an appropriate hardness as a base material for friction materials. Have. The perovskite alkali earth titanate metal structure, two-phase composite powder was mixed in the crystal grains of the alkali metal titanate of layered or tunneled structure [M ₂ Ti _n O _{2n + 1],} or their grain, The friction material of the present invention based on a three-phase composite powder in which crystal grains of titania (TiO ₂ ) are mixed in the base material is an improved high-performance material that is superior to a friction material based on a single-phase material of alkali metal titanate. It has a friction coefficient and maintains a high friction coefficient stably over a wide temperature range.

The composite ratio of the respective crystal phases constituting the composite titanium compound powder blended as the base material is arbitrary,
The 2-phase composite powder consisting of a titanate alkaline earth metal [RTiO _3] and the alkali metal titanate [M ₂ Ti _n O _{2n + 1],} the ratio of _{RTiO 3 / M 2 Ti n O} 2n + 1 ( molar ratio ): Having a composite ratio of (0.2-40) / 1,
In a three-phase composite powder in which titania (TiO ₂ ) is mixed, R
Use Preferred composite powder having the composite ratio of the ratio of _{TiO 3 / M 2 Ti n O} 2n +1 / TiO 2 ( molar ratio): 0.2 to 40) / 1 / (0.1-20) To be done. The compounding ratio of the composite powder is appropriately in the range of about 3 to 50% by weight. If the amount is less than about 3% by weight, the compounding effect is small. On the other hand, if the amount exceeds 50% by weight, the effect of improving the friction and wear characteristics is saturated, and there is no advantage of increasing the amount further.

The above-mentioned composite titanium compound powder is a reference example described later.
As shown in₂(Or TiO by heating₂To
Titanium compound produced)) and RO [R is an alkaline earth
Metal] (or alkaline earth that produces RO when heated)
Metal compound) and M₂O [M is an alkali metal] (or
M by heating₂Alkali metal compound that produces O)
Z ≧ X + nY (where X is the number of moles of RO and Y is M₂
The number of moles of O, Z is TiO ₂The number of moles of n is the same as above)
The raw material mixture is prepared by blending at a ratio of 700 to 1
It is manufactured by baking at 300 ° C. Obtained
Alkaline Earth Metal Titanate and Titanium Constituting Composite Powder
The ratio of alkali metal phosphate is RO and M in the raw material preparation.
₂It is arbitrarily controlled by the compounding ratio of O.

The friction material of the present invention can be compounded as a base material with the above-mentioned composite titanium compound powder in combination with other known materials. Examples thereof include polyamide (nylon) fiber, aramid fiber, steel fiber, stainless fiber, copper fiber, brass fiber, carbon fiber, glass fiber, alumina / silica fiber, rock wool and wood pulp. One or more of these are arbitrarily selected,
The compounding amount is not particularly limited, but the compounding amount may be about 10 to 65% by weight in total with the composite titanium compound powder. If necessary, the base material is a silane coupling agent (aminosilane, vinylsilane, epoxysilane, methacryloxylan, mercaptoxylan, etc.) or titanate for the purpose of improving dispersibility and binding property with the binder resin. A surface treatment (coupling treatment) with a system coupling agent (isopropyltriisostearoyl titanate, di (dioctylpyrophosphate) ethylene titanate, etc.) is performed according to a conventional method and used.

If desired, the friction material of the present invention may be a known friction / wear modifier, for example, vulcanized or unvulcanized natural / synthetic rubber powder, cashew resin powder, resin dust, organic powder such as rubber dust, Natural / artificial graphite, molybdenum disulfide, antimony trisulfide, inorganic powder such as barium sulfate, calcium carbonate, metal powder such as copper, aluminum, zinc, iron, alumina, silica, chromium oxide, copper oxide, antimony trioxide, oxidation One or more components selected from oxide powders such as titanium and iron oxide are used in an appropriate amount (for example, 20 to 20) for the purpose of improving friction and wear characteristics (friction coefficient, wear resistance, vibration characteristics, naki, etc.). 70% by weight). Also, it is no different from ordinary friction materials that various additives, for example, rust preventive agents, lubricants, abrasives, and the like are blended in appropriate amounts (for example, 50% by weight or less) depending on the application and usage.

The resin component which is a binder is a commonly used material such as phenol resin, formaldehyde resin,
Examples thereof include thermosetting resins such as epoxy resins and silicone resins, thermosetting resins modified with these (cashew oil modification, dry modification, etc.), rubber-based resins such as natural rubber, styrene-butadiene rubber, nitrile rubber and the like.

The preparation of the raw material mixture for producing the friction material of the present invention is the same as the conventional friction material except that the above-mentioned composite titanium compound powder is used as the base material, and the production process thereof is the same. However, no special conditions or restrictions are imposed. That is, a base material is dispersed in a binder resin, and a friction wear modifier, which is blended if necessary, and a rust preventive agent, a lubricant, an abrasive agent, etc. are added and uniformly mixed to prepare a raw material composition. Then, pre-molding is followed by heating and pressurization (pressurization pressure of about 10 to 40 MPa, temperature of about 150 to 200) by die molding or the like.
C.) and take out from the mold. Then, if necessary, heat treatment (temperature about 150 to 200.degree. C., holding time about 1 to 12 hours) is performed, and then the molded body is machined and polished. A friction material having a predetermined shape is finished by processing. Alternatively, a step of dispersing and suspending the raw material composition in water, etc., making a paper with a paper making net, squeezing water to make sheets, stacking an appropriate number of sheets, and binding-molding under heating and pressure. It is also possible to obtain a predetermined friction material by subjecting the molded body to mechanical processing or polishing processing via the above.

[0012]

【Example】

(1) Preparation of raw material composition See Table 1. In the table, the symbols in the base material column are as follows. The base materials A _{1 to} A ₄ are according to the reference example described later (composite ratio is shown by molar ratio). A ₁ : Composite titanium compound (CaTiO ₃ / K ₂ Ti ₆ O ₁₃ = 2
/ 1) A _2: complex titanium compound _{(CaTiO 3 / K 2 Ti 6} O 13 = 4
/ 1) A _3: complex titanium compound _{(CaTiO 3 / K 2 Ti 6} O 13 = 1
0/1) A _4: complex titanium compound _{(CaTiO 3 / K 2 Ti 6} O 13 / Ti
O ₂ = 4/1/1) (powder particle size: 10 to 100 in each case)
μm) B ₁ : potassium hexatitanate (K ₂ Ti ₆ O ₁₃ ) single phase (spherical particles) (powder particle size: 10 to 100 μm) B ₂ : potassium hexatitanate (K ₂ Ti ₆ O ₁₃ ) single phase ( Fiber (fiber length: 150 μm (average), fiber diameter: 30 μm
(Average) C: Calcium titanate (CaTiO ₃ ) single-phase powder (powder particle size: 1 to 5 μm) D: Asbestos fiber (6 class)

(2) Molding of friction material The raw material composition is pre-molded (pressing force: 14.7 MPa = 150 Kg / c)
m ^2, temperature: room temperature, time: after 1 minute), the binder forming with a die (pressure: 14.7MPa = 150Kg / cm ^2, temperature: 170
℃, pressurizing and holding time: 5 minutes), after molding, mold release and heat treatment in a drying furnace (hold at 180 ℃ for 3 hours). After that, cut it to a specified size, add polishing process, and test friction material (
Get the disk pad).

(3) Friction test Each test friction material was subjected to a second efficacy test in accordance with "JASO C 406 Passenger Car Brake Device Dynamometer Test Method", and the results shown in the lower column of Table 2 were obtained. (Test condition) Initial braking speed: 50 km / h, 100 km / h. Deceleration: 0.3G

[0015]

[Table 1]

As shown in the results of the friction test, as the base material, those using alkali metal titanate single-phase materials (Comparative Examples 1 and 2) and alkaline earth metal titanate single-phase materials were used. Alkaline earth metal titanate-compared to the one (Comparative Example 3) and the one using asbestos (Comparative Example 4).
The friction materials of the invention examples (Examples 1 to 4) using the alkali metal titanate composite powder have a high friction coefficient from a relatively low initial braking speed to a high initial braking speed accompanied by a remarkable temperature rise of the friction surface. ing.

[0017]

[Reference example]

(Production of alkaline earth metal titanate-alkali metal titanate composite powder) Purified anatase (TiO ₂ ) powder, calcium carbonate (CaCO ₃ ) powder, and potassium carbonate (K
₂ CO) powder is mixed with the following compounding ratio. Raw material A ₁ : TiO ₂ / CaO / K ₂ O (molar ratio) = 8
/ 2/1 Raw material A ₂ : TiO ₂ / CaO / K ₂ O (molar ratio) = 10
/ 4/1 Raw material A ₃ : TiO ₂ / CaO / K ₂ O (molar ratio) = 16
/ 10/1 Raw material A ₄ : TiO ₂ / CaO / K ₂ O (molar ratio) = 11
/ 4/1 A suitable amount of water (about twice the total amount of the powder) is added to the mixed powder to make a slurry, which is dried by a spray dryer to obtain granulated powder (average particle size: about 40 μm). Temperature 115
Bake for 1 hour at 0 ° C. Through the above steps, composite titanium compound powders A _1, A _2, A _3, and A ₄ were obtained. Each powder is granular powder (average particle size: about 33 μm), and the granules are calcium titanate (CaTiO ₃ ), potassium hexatitanate (K ₂ Ti).
It is composed of fine crystal grains (submicron order) such as ₆ O ₁₃ ) and titania (TiO ₂ ). The composite rate of the crystal phase of each powder is as follows (molar ratio, weight ratio in parentheses). CaTiO ₃ / K ₂ Ti ₆ O ₁₃ / TiO ₂ composite powder A ₁ : 2/1/0 (32/68/0) composite powder A ₂ : 4/1/0 (49/51/0) composite powder A ₃ : 10/1/0 (70/30/0) Composite powder A ₄ : 4/1/1 (45/48/7)

[0018]

The friction material of the present invention has an improved friction coefficient and wear resistance as a compounding effect of the composite titanium compound powder, and exhibits excellent fade resistance and wear resistance even in a high temperature range. . Therefore, it is useful as a brake lining, a disk pad, a clutch facing, etc., which constitutes a braking device for automobiles, vehicles, aircrafts, and various industrial machines, and enables a reduction in size and weight of the braking device.
The effects of improving / stabilizing the braking function and improving durability are obtained.

Claims (3)

[Claims] 1. A friction material obtained by binding and molding a mixture of a resin and a base material, wherein the base material is RTiO ₃ [wherein R is an alkaline earth metal] as the base material. and the crystal grains of the metal, wherein, M is an alkali metal, n represents 2-6] M ₂ Ti _n O _{2n + 1} are blended composite titanium compound powder composed of crystal grains of alkali metal titanate represented by Friction material characterized by being 2. Binder molding of a mixture of a resin and a base material
In the friction material formed by using₃〔formula
Where R is an alkaline earth metal]
Li-earth metal crystal grains and M₂Ti_nO_{2n + 1}[Where M is
Alkali metal, n is 2 to 6]
Li metal crystal grains and titania (TiO ₂) Crystal grains
The composite titanium compound powder consisting of
Friction material to collect. 3. The alkaline earth metal titanate is calcium titanate (CaTiO ₃ ), and the alkali metal titanate is potassium hexatitanate (K ₂ Ti ₆ O ₁₃ ). The friction material according to claim 2.