Non-asbestos friction material composition, friction material using same, and friction member

Abstract

A non-asbestos frictional material composition is provided, which is capable of provide a frictional material with low environmental load and with excellent friction coefficient, anti-crack properties, and abrasion resistance compared with conventional ones. Furthermore, a frictional material and a friction member formed by using this non-asbestos frictional material composition are provided. The non-asbestos frictional material composition containing a binder, an organic filler, an inorganic filler, and a fiber base material, includes: copper in a content of 5 mass % or less as a copper element; a metal fiber other than a copper fiber and a copper alloy fiber in a content of 0.5 mass % or less; cashew dust in a content of 1.5-4.5 mass % as the organic filler; zirconium oxide with a particle size of 30 m or less in a content of 30-45 mass % but not containing zirconium oxide with a particle size of more than 30 m as the inorganic filler.

Claims

1. A non-asbestos frictional material composition containing a binder, an organic filler comprising cashew dust and a rubber filler, an inorganic filler, and a fiber base material, comprising: copper in a content of 5 mass % or less as a copper element; a metal fiber other than a copper fiber and a copper alloy fiber in a content of 0.5 mass % or less; cashew dust in a content of 1.5-4.5 mass %, wherein a mass ratio of the cashew dust to the organic filler other than the cashew dust falls within a range of 2/1-10/1; zirconium oxide with a particle size of 30 m or less in a content of 30-45 mass % but not containing zirconium oxide with a particle size of more than 30 m as the inorganic filler.

2. The non-asbestos frictional material composition according to claim 1, wherein the mean particle size of the zirconium oxide falls within the range of 1-7 m.

3. The non-asbestos frictional material composition according to claim 1, wherein the mass ratio of the cashew dust to the organic filler other than the cashew dust falls within a range of 2/1-9/1.

4. The non-asbestos frictional material composition according to claim 1, wherein the mass ratio of the cashew dust to the organic filler other than the cashew dust falls within a range of 2/1-6/1.

5. The non-asbestos frictional material composition according to claim 1, wherein the content of the cashew dust is 1.8-4.2 mass %.

6. The non-asbestos frictional material composition according to claim 1, wherein the content of the cashew dust is 2.0-4.0 mass %.

7. A frictional material being formed from the non-asbestos frictional material composition according to claim 1.

8. A friction member being formed from a frictional material formed from the non-asbestos frictional material composition according to claim 1 and a backing plate.

9. A frictional material being formed from the non-asbestos frictional material composition according to claim 2.

10. A friction member being formed from a frictional material formed from the non-asbestos frictional material composition according to claim 2 and a backing plate.

Description

EXAMPLES

(1) The non-asbestos frictional material composition, the frictional material, and the friction member of the present invention will be described in detail in reference to Examples and Comparative examples. However, the present invention is not limited to these examples.

Examples 1-6 and Comparative Examples 1-10

(2) (Production of Disc Brake Pad)

(3) The materials were blended according to the blend ratio shown in Tables 1 and 2 to obtain the frictional material compositions of Examples 1-6 and Comparative examples 1-10. Each of the frictional material compositions was mixed using a Loedige mixer (available from MATSUBO Corporation, brand name: Loedige mixer M20). This mixture was preformed with a molding press (available from OJIKIKAI CO., LTD). The obtained preformed material was hot press-molded together with an iron backing plate (available from Hitachi Automotive Systems, Ltd.) using a molding press (SANKI SEIKO CO., LTD.) under the condition at a molding temperature of 145 C. and a molding pressure of 30 MPa for 5 minutes. The obtained molded article was heated at 200 C. for 4.5 hours, polished with a rotary polisher, and then scorched at 500 C. to obtain the disc brake pads of Examples 1-6 and Comparative examples 1-10. In these examples and comparative examples, disc brake pads with having a backing plate thickness of 6 mm, a frictional material thickness of 11 mm, and a frictional material projected area of 52 cm.sup.2 were produced.

(4) (Evaluation of Friction Coefficient)

(5) The friction coefficient was measured based on Japanese Automotive Standards Organization JASO C406. The average of friction coefficients measured in the second effectiveness test was calculated.

(6) (Evaluation of Anti-Crack Properties)

(7) The braking was repeated at a brake temperature of 400 C. (initial speed: 50 km/h, closing speed: 0 km/h, deceleration: 0.3 G, brake temperature before braking: 100 C.) based on JASO C427 until the thickness of the each frictional material was reduced to half. The generation of cracks on the side face and the frictional surface of the each frictional material was measured. The generation of cracks was evaluated with the following scores 1-3. Score 1: No cracks were generated. Score 2: Cracks were generated to the extent where a 0.1 mm thickness gauge does not enter the frictional surface or the side face of the frictional material. Score 3: Cracks were generated to the extent where a 0.1 mm thickness gauge enters the frictional surface or the side face of the frictional material.

(8) When cracks were generated to the extent where a 0.1 mm thickness gauge does not enter one of the frictional surface and the side face of the frictional material but enters the other, the generation of cracks was evaluated as Score 3.

(9) (Evaluation of Abrasion Resistance)

(10) The abrasion resistance was measured based on Japanese Automotive Standards Organization JASO C427. The abrasion loss of the each frictional material, which corresponds to 1000 times of braking at brake temperatures of 100 C. and 300 C., were evaluated.

(11) The friction coefficient, the abrasion resistance, and the anti-crack properties were evaluated at an inertia of 7 kgf.Math.m.Math.s.sup.2 with a dynamometer (available from SANKI SEIKO CO., LTD.) based on the above-mentioned JASO C406 and JASO C427. The above-mentioned evaluation was carried out using a ventilated disc rotor (material: FC190, available from KIRIU Corporation) and a general pin sliding collet type caliper.

(12) The evaluation results are shown in Tables 1 and 2.

(13) Details of the each structural component shown in Tables 1 and 2 are as follows. The mean particle size and the maximum particle size as described below were measured with a laser diffraction/scattering particle size distribution measurement device LA.Math.920 (available from HORIBA, Ltd.).

(14) (Binder)

(15) Phenol resin: available from Hitachi Chemical Co., Ltd. (brand name: HP491UP)

(16) (Organic Filler)

(17) Cashew dust: available from Tohoku Chemical Industries, Ltd (brand name: FF-1056, maximum particle size: 500 m)

(18) (Inorganic Filler)

(19) Barium sulfate: available from SAKAI CHEMICAL INDUSTRY CO., LTD. (brand name: Barium sulfate BA)

(20) Graphite: available from TIMCAL (brand name: KS75) Mica: available from Imerys (Brand name: 325HK, mean particle diameter 25 m, maximum particle size 100 m) Potassium titanate: available from Kubota Corporation (Brand name: TXAX-MA, plate-like potassium titanate)

(21) Tin sulfide: available from Chemetall (brand name: Stannolube)

(22) Calcium hydroxide: available from Chichibu Lime Industry CO., LTD (brand name: SA-149)

(23) Zirconium oxide A: available from DAIICHI KIGENSO KAGAKU KOGYO CO., LTD. (brand name: BR-3QZ, mean particle diameter: 2.0 m, maximum particle size: 15 m)

(24) Zirconium oxide B: available from DAIICHI KIGENSO KAGAKU KOGYO CO., LTD. (brand name: BR-QZ, mean particle diameter: 6.5 m, maximum particle size: 26 m)

(25) Zirconium oxide C: available from DAIICHI KIGENSO KAGAKU KOGYO CO., LTD. (brand name: BR-12QZ, mean particle diameter: 8.5 m, maximum particle size: 45 m)

(26) (Organic Fiber)

(27) Aramid fiber: available from DU PONT-TORAY CO., LTD. (brand name: 1F538)

(28) (Metal Fiber)

(29) Copper fiber: available from Sunny Metal (brand name: SCA-1070)

(30) Iron fiber: available from GMT (brand name: #0)

(31) (Inorganic Fiber)

(32) Mineral fiber: available from LAPINUS FIBRES B.V (brand name: RB240Roxul 1000, mean fiber length: 300 m)

(33) TABLE-US-00001 TABLE 1 Table 1 Examples 1 2 3 4 5 6 Frictional material Binder Phenol resin 8 8 8 8 8 8 composition (mass %) Organic filler Cashew dust 2 3 4 3 3 3 SBR powder 1 1 1 1 1 1 Inorganic filler Barium sulfate 28 22 21 17 26 22 Graphite 5 5 5 5 5 5 Mica 5 5 5 5 5 5 Potassium titanate 4 4 4 4 4 4 Tin sulfide 4 4 4 4 4 4 Calcium hydroxide 2 2 2 2 2 2 Zirconium oxide A 32 37 37 42 37 0 Zirconium oxide B 0 0 0 0 0 37 Zirconium oxide C 0 0 0 0 0 0 Fiber base material Aramid fiber 2 2 2 2 2 2 Copper fiber 4 4 4 4 0 4 Iron fiber 0 0 0 0 0 0 Mineral fiber 3 3 3 3 3 3 Content of copper as copper element (mass %) 4 4 4 4 0 4 Content of metal fiber other than copper fiber and 0 0 0 0 0 0 copper alloy fiber (iron fiber) (mass %) Content of cashew dust (mass %) 2 3 4 3 3 3 Content of zirconium oxide (mass %) 32 37 37 42 37 37 Evaluation Friction coefficient 0.40 0.40 0.40 0.41 0.40 0.40 Anti-crack properties Score 1 Score 1 Score 1 Score 1 Score 1 Score 1 Abrasion resistance 100 C. 0.101 0.095 0.098 0.111 0.114 0.108 (mm/1000 brakings) 300 C. 0.55 0.53 0.56 0.62 0.67 0.62

(34) TABLE-US-00002 TABLE 2 Comparative examples 1 2 3 4 5 6 7 8 9 10 Frictional Binder Phenol resin 8 8 8 8 8 8 8 8 8 8 material Organic Cashew dust 3 1 1 1 5 3 3 3 3 3 compo- filler SBR powder 1 1 1 1 1 1 1 1 1 1 sition Inorganic Barium sulfate 16 36 40 24 20 34 9 22 22 21 (mass %) filler Graphite 5 5 5 5 5 5 5 5 5 5 Mica 5 5 5 5 5 5 5 5 5 5 Potassium titanate 4 4 4 4 4 4 4 4 4 4 Tin sulfide 4 4 4 4 4 4 4 4 4 4 Calcium hydroxide 2 2 2 2 2 2 2 2 2 2 Zirconium oxide A 37 25 25 37 37 25 50 0 18 37 Zirconium oxide B 0 0 0 0 0 0 0 0 0 0 Zirconium oxide C 0 0 0 0 0 0 0 37 19 0 Fiber base Aramid fiber 2 2 2 2 2 2 2 2 2 2 material Copper fiber 10 4 0 4 4 4 4 4 4 4 Iron fiber 0 0 0 0 0 0 0 0 0 1 Mineral fiber 3 3 3 3 3 3 3 3 3 3 Content of copper as copper element (mass %) 10 4 0 4 4 4 4 4 4 4 Content of metal fiber other than copper fiber and 0 0 0 0 0 0 0 0 0 1 copper alloy fiber (iron fiber) (mass %) Content of cashew dust (mass %) 3 1 1 1 5 3 3 3 3 3 Content of zirconium oxide (mass %) 37 25 25 37 37 25 50 37 37 37 Evalu- Friction coefficient 0.40 0.37 0.35 0.38 0.36 0.37 0.39 0.41 0.41 0.41 ation Anti-crack properties Score 1 Score 2 Score 3 Score 2 Score 2 Score 1 Score 3 Score 1 Score 1 Score 1 Abrasion resistance 100 C. 0.113 0.143 0.169 0.147 0.117 0.128 0.153 0.132 0.123 0.148 (mm/1000 brakings) 300 C. 0.60 0.73 1.32 0.82 0.74 0.77 1.01 0.80 0.71 1.11

(35) Examples 1-6 exhibit friction coefficient, anti-crack properties, and abrasion resistance on about the same level as those of Comparative example 1 containing copper in a content of more than 5 mass % as a copper element. Furthermore, Examples 1-6 have excellent friction coefficient, anti-crack properties, and/or abrasion resistance compared with Comparative examples 2-4 containing cashew dust in a content of less than 1.5 mass %; Comparative example 5 containing cashew dust in a content of more than 4.5 mass %; Comparative examples 2, 3 and 6 containing zirconium oxide in a content of less than 30 mass %; Comparative example 7 containing zirconium oxide in a content of more than 45 mass %; Comparative examples 8 and 9 containing zirconium oxide with a particle size of more than 30 m; and Comparative example 10 containing a metal fiber other than a copper fiber and a copper alloy fiber in a content of more than 0.5 mass %.

INDUSTRIAL APPLICABILITY

(36) The non-asbestos frictional material composition of the present invention, and a frictional material and a friction member formed by using the composition have low environmental load due to the low content of copper in abrasion powder generated during the braking, can provide excellent friction coefficient, anti-crack properties, and abrasion resistance and are therefore suitable for a frictional material and a friction member such as a brake pad for a car, compared with conventional ones.