JP3229777B2 - Friction material - Google Patents

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 and the like in a braking device for an automobile, a railway vehicle, an aircraft, an industrial machine and the like.

[0002]

2. Description of the Related Art The friction material of the above-mentioned braking device is made of resin (phenolic).
Resin, epoxy resin, etc.)
And a friction / wear modifier (barium sulfate
Of the mixture to which it is added under heat and pressure.
It is manufactured by Asbestos as a base material
Fiber has been used, but the friction material
Wear damage increases significantly with
It is easy to cause a sharp drop / fade phenomenon. Also asbestos
Fibers have also been pointed out as a carcinogenic problem. For this reason,
Asbestos substitutes are being developed, and as a base material,
M_TwoTi_nO_{2n + 1}[Where M is K, Na, Li, Rb, etc.
Alkali metal, n = 2 to 6]
Potassium metal fiber [typically potassium hexatitanate fiber (K
_TwoTi₆O ₁₃)] Or alumina / silica fiber etc.
Practical use of blended friction materials has been attempted (for example,
JP-A-61-191599, JP-A-1-29455
No. 3 publication).

[0003]

In order to meet the demands for miniaturization and weight reduction of automobile brake devices, a friction material having a high friction coefficient and capable of stably maintaining the high friction coefficient 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, abrasion resistance, reinforcing property, etc., and having an appropriate hardness as a friction material. The manufactured friction material exhibits friction and wear characteristics superior to the conventional friction material using asbestos fiber. However, fade resistance and a coefficient of friction in a high temperature range (about 300 ° C. or higher) are not sufficient. For the purpose of further improving the fade resistance, etc., it has been proposed to compound potassium titanate fiber and alumina / silica fiber. However, since alumina / silica fiber has a Mohs hardness of about 7 and is hard, the compounding of the compound is required. As a result, the opponent material aggression becomes strong. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems associated with the conventional friction material and to provide a friction material capable of stably maintaining the 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 material. 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] Or a composite titanium compound powder comprising these crystal grains and titania (TiO ₂ ) crystal grains.

[0005]

[Action] Alkaline earth metal titanate [RTiO ₃ ] (R
Is a compound having a perovskite-type crystal structure, which is excellent in strength, heat resistance, heat insulation, abrasion resistance, etc., and has an appropriate hardness as a base material of a friction material. Having. 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 together has improved improved properties over a friction material based on a single-phase material of alkali metal titanate. It has a coefficient of friction and stably maintains a high coefficient of friction over a wide temperature range.

[0006] The composite ratio of each crystal phase constituting the composite titanium compound powder blended as a 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 to 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) Is done. The compounding ratio of the composite powder is suitably in the range of about 3 to 50% by weight. If the amount is less than about 3% by weight, the effect of the compounding is small. On the other hand, if it exceeds 50% by weight, the effect of improving the friction and wear characteristics is saturated, and there is no advantage to further increase the amount.

The above-mentioned composite titanium compound powder is referred to in the following Reference Example.
As shown in FIG._Two(Or TiO by heating_TwoTo
Generated titanium compound)) and RO [R is an alkaline earth
Metal] (or alkaline earth that generates RO upon heating)
Metal compound) and M_TwoO [M is an alkali metal] (or
M by heating_TwoAn alkali metal compound that produces O)
Is represented by Z ≧ X + nY (where X is the number of moles of RO, and Y is M_Two
Number of moles of O, Z is TiO _TwoAnd n is the same as described above)
To prepare a raw material mixture,
It is manufactured by firing at 300 ° C. Obtained
Alkaline earth metal titanate and titanium constituting the composite powder
The ratio of alkali metal phosphate to RO and M
_TwoIt is arbitrarily controlled by the mixing ratio of O.

[0008] The friction material of the present invention may be compounded with other known materials in combination with the composite titanium compound powder as a base material. For example, polyamide (nylon) fiber, aramid fiber, steel fiber, stainless fiber, copper fiber, brass fiber, carbon fiber, glass fiber, alumina / silica fiber, rock wool, wood pulp and the like can be mentioned. One or more of these are arbitrarily selected,
The compounding amount is not particularly limited, but the compounding amount may be in the range of about 10 to 65% by weight in total with the composite titanium compound powder. The base material may be a silane coupling agent (aminosilane, vinylsilane, epoxysilane, methacryloxysilane, mercaptooxysilane, etc.) or titanate, if necessary, for the purpose of improving dispersibility and binding with the binder resin. Surface treatment (coupling treatment) with a system coupling agent (isopropyl triisostearoyl titanate, di (dioctyl pyrophosphate) ethylene titanate, etc.) is performed according to a conventional method and used.

The friction material of the present invention may be, if desired, a known friction and wear modifier, for example, an organic powder such as a vulcanized or unvulcanized natural or synthetic rubber powder, cashew resin powder, resin dust, rubber dust, or the like. Inorganic powders such as natural and artificial graphite, molybdenum disulfide, antimony trisulfide, barium sulfate, calcium carbonate, metal powders such as copper, aluminum, zinc, iron, alumina, silica, chromium oxide, copper oxide, antimony trioxide, and oxide One or two or more components selected from oxide powders such as titanium and iron oxide are added in an appropriate amount (for example, 20 to 20) for the purpose of improving the friction and wear characteristics (friction coefficient, wear resistance, vibration characteristics, naki, etc.). 70% by weight). Also, it is not different from ordinary friction materials in that various additives, for example, rust preventives, lubricants, abrasives, and the like are blended in an appropriate amount (for example, 50% by weight or less) in accordance with the use and usage mode.

[0010] The resin component serving as a binder includes commonly used materials such as phenol resin, formaldehyde resin, and the like.
Examples thereof include thermosetting resins such as epoxy resins and silicone resins, and thermosetting resins thereof (modified with cashew oil and dryness), and rubber resins such as natural rubber, styrene butadiene rubber, and nitrile rubber.

The preparation of the raw material mixture for producing the friction material of the present invention does not differ from the conventional general friction material except that the above-mentioned composite titanium compound powder is used as a base material, and the production process is not limited. No special conditions or restrictions are imposed. That is, a base material is dispersed in a binder resin, and a friction and wear modifier, a rust preventive, a lubricant, a grinding agent, and the like, which are added as necessary, are added, and the mixture is uniformly mixed to prepare a raw material composition. Then, after the preforming, by molding and the like, under heating and pressurizing (pressure: about 10 to 40 MPa, temperature: about 150 to 200 MPa)
C.), and after taking out from the mold, heat-treating (temperature: about 150 to 200 ° C., holding time: about 1 to 12 hours) if necessary in a heating furnace, and thereafter, machining and polishing the formed body It is processed into a friction material having a predetermined shape. As another method, a step of dispersing and suspending the raw material composition in water or the like, making it through a paper net, squeezing water to form a sheet, stacking an appropriate number of sheets, and binding and forming the sheet under heating and pressure. , The molded body can be machined or polished to obtain a predetermined friction material.

[0012]

【Example】

(1) Preparation of raw material composition See Table 1. In the table, the symbols in the base material column are as follows. Substrates A _{1 to} A ₄ are based on Reference Examples described later (composite ratios are shown by molar ratio). A ₁ : Composite titanium compound (CaTiO ₃ / K ₂ Ti ₆ O ₁₃ = 2
/ 1) A ₂ : Composite titanium compound (CaTiO ₃ / K ₂ Ti ₆ O ₁₃ = 4)
/ 1) A ₃ : Composite titanium compound (CaTiO ₃ / K ₂ Ti ₆ O ₁₃ = 1)
0/1) A ₄ : Composite 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: Single phase powder of calcium titanate (CaTiO ₃ ) (powder particle size: 1 to 5 μm) D: Asbestos fiber (6 classes)

(2) Forming of friction material The raw material composition is preformed (pressing force: 14.7 MPa = 150 kg / c)
m ² , temperature: normal temperature, time: 1 minute), and then binding with a mold (pressure: 14.7 MPa = 150 kg / cm ² , temperature: 170)
C., pressurization holding time: 5 minutes), after molding, release from the mold and heat treatment in a drying oven (holding at 180 ° C for 3 hours). After that, cut to a predetermined size, add a grinding process, test friction material (
Disk pad).

(3) Friction test JASO C406"Passenger car brakes
2nd efficacy test based on "Device dynamometer test method"
Do the table1The results shown in the lower column were obtained. (Test conditions) Initial braking speed: 50 km / h, 100 km / h_.  Deceleration: 0.3G

[0015]

[Table 1]

As shown in the above-mentioned friction test results, the base materials using the alkali metal titanate single-phase material (Comparative Examples 1 and 2) and the alkaline earth titanate single-phase material were used. (Comparative Example 3) and those using asbestos (Comparative Example 4).
The friction material of the invention example using the alkali metal titanate composite powder (Examples 1 to 4) has a high friction coefficient from a relatively low initial braking speed to a high initial braking speed accompanied by a significant 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) mixing the powder in the mixing ratio below. 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 An appropriate amount of water (about twice the total amount of powder) is added to the mixed powder to form a slurry, and the slurry is dried with a spray dryer to obtain a granulated powder (average particle size: about 40 μm). Temperature 115
Firing for 1 hour at 0 ° C. Composite titanium compound in the above step a powder _{A 1, A 2, A 3} , and to obtain a A _4. Each powder is a granule 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 ratio 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 abrasion resistance as a compounding effect of the composite titanium compound powder, and exhibits excellent fade resistance and abrasion resistance even at a high temperature range. . Therefore, it is useful as a brake lining, a disc pad, a clutch facing, etc. constituting a braking device for automobiles, vehicles, aircrafts, and various industrial machines, and it is possible to cope with a reduction in size and weight of the braking device.
Effects such as improvement and stabilization of the braking function and improvement of durability can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F16D 69/02 F16D 69/02 C // C08L 61:00 C08L 61:00 (56) References JP-A-6-248091 (JP JP-A-8-53553 (JP, A) JP-A-7-26033 (JP, A) JP-A-7-26032 (JP, A) JP-A-7-53214 (JP, A) 8-337420 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/14 C01G 23/00 C09K 3/14 520 F16D 69/02 C08L 61/00-61/34

Claims (3)

(57) [Claims] An alkaline earth titanate represented by RTiO ₃ (where R is an alkaline earth metal) as a substrate in a friction material obtained by binding and molding a mixture of a resin and a substrate. 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 that. 2. Binder molding of a mixture of a resin and a base material
In the friction material thus formed, RTiO is used as a base material._Three〔formula
Wherein R is an alkaline earth metal]
Crystal grains of lithium earth metal and M_TwoTi_nO_{2n + 1}[Where M is
Alkali metal, n is an alkali titanate represented by 2 to 6]
Li metal crystal grains and titania (TiO _Two)
Special compound titanium powder
A characteristic friction material. 3. The method according to claim 1, wherein 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.