FRICTION MATERIAL COMPOSITION, FRICTION MATERIAL, AND DISC BRAKE PAD

Abstract

[Object] This invention, on an assumption that the environmental situation must be considered, reduces the brake noise, prevents the reduction of the braking effectiveness in the high temperature range, and improves the wear resistance.

[Means to Resolve] In the NAO friction material composition that does not practically contain a copper component, this invention contains the first substance made of such as the calcium carbonate that is the substance which becomes the sintered body during braking and is the precursor of the sintered body which keeps the powder generated from the disc rotor, and the second substance made of such as the fluoropolymer that is the sintering additive which aids sintering of the first substance.

[Selected Drawing(s)] None

Claims

1. A non-asbestos-organic (NAO) friction material composition, containing a binder, a fiber base, an inorganic filler, and an organic filler that does not practically contains a copper component, wherein said NAO friction material composition includes (1) a first substance that is a substance which becomes a sintered body during braking and is a precursor of said sintered body which keeps powder generated from a disc rotor, and (2) a second substance that is a sintering additive which aids sintering of the first substance.

2. The NAO friction material composition of claim 1, wherein said first substance is a calcium carbonate as an inorganic filler, and 5-20 weight % of said calcium carbonate, relative to the entire amount of the friction material composition, is contained in the friction material composition, and said second substance is a fluoropolymer as an organic filler, and 1-5 weight % of said fluoropolymer, relative to the entire amount of the friction material composition, is contained in the friction material composition.

3. The NAO friction material composition of claim 1, wherein 10-35 weight % a lithium potassium titanate, relative to the entire amount of the friction material composition, is contained in the friction material composition.

4. The NAO friction material composition of claim 2, wherein 10-35 weight % a lithium potassium titanate, relative to the entire amount of the friction material composition, is contained in the friction material composition.

5. A friction material manufactured using the NAO friction material composition according to claim 1.

6. The friction material manufactured using the NAO friction material composition according to claim 2.

7. The friction material manufactured using the NAO friction material composition according to claim 3.

8. The friction material manufactured using the NAO friction material composition according to claim.

9. A disc brake pad mounting the friction material on a back plate according to claim 5.

10. A disc brake pad mounting the friction material on a back plate according to claim 6.

11. A disc brake pad mounting the friction material on a back plate according to claim 7.

12. A disc brake pad mounting the friction material on a back plate according to claim 8.

Description

EMBODIMENT

[0048] In the following section, each embodiment and comparative example of the friction material composition and the friction material that employs the friction material composition is explained concretely. Here, the friction material in each embodiment and comparative example is manufactured using the matching friction material composition in each embodiment and comparative example.

[0049] The manufacturing method for the friction material in each embodiment and comparative example is as follows.

[0050] [Manufacturing Method for Friction Material in Embodiments 1-14/Comparative Examples 1-4] The friction material compositions shown in Table 1 and Table 2 were mixed by Loedige mixer for about 5 minutes and were pressed in the forming die under 30 MPa for about 10 seconds, thereby conducing a pre-forming process to produce the preformed intermediate item. That intermediate item was superposed on a steel back plate, which was prewashed, surface-treated, and adhesive coated thereon, and was heat-formed in a heat forming die at the forming temperature of 150 centigrade under the forming pressure of 40 MPa for about 10 minutes. Then, the heat-formed intermediate item was heat-treated (cured) at 200 centigrade for about 5 hours, and the obtained item through the above-processes was grinded to form a friction surface to complete a disc brake pad for an automobile (Embodiments 1-14, Comparative Examples 1-4).

[0051] In the respective friction material composition of the embodiments, containing the appropriate amount of the calcium carbonate and the fluoropolymer is important. To measure and determine the appropriate amount, for example, setting a center weight % of the calcium carbonate as 12 weight % and setting a center weight % of the fluoropolymer as 3 weight %, the amount of calcium carbonate and the amount of fluoropolymer were increased or decreased to evaluate the various appropriate amounts.

TABLE-US-00001 TABLE 1 Embodiments 1 2 3 4 5 6 7 8 9 binder phenol resin 10 10 10 10 10 10 10 10 10 fiber base aramid fiber 6 6 6 6 6 6 6 6 6 inorganic filler graphite 2 2 2 2 2 2 2 2 2 molybdenum disulfide 3 3 3 3 3 3 3 3 3 zirconium oxide 10 10 10 10 10 10 10 10 10 zirconium silicate 1 1 1 1 1 1 1 1 1 calcium hydroxide 3 3 3 3 3 3 3 3 3 barium sulfide 22 21 20 19 18 27 25 17 12 calcium carbonate 12 12 12 12 12 5 7 15 20 lithium potassium 25 25 25 25 25 25 25 25 25 titanate potassium hexatitanate 0 0 0 0 0 0 0 0 0 organic filler fluorine based polymer 1 2 3 4 5 3 3 3 3 cashew dust 3 3 3 3 3 3 3 3 3 tire tread rubber 2 2 2 2 2 2 2 2 2 pulverized powder Total (weight %) 100 100 100 100 100 100 100 100 100 Comparative Embodiments Examples 10 11 12 13 14 1 2 3 4 binder phenol resin 10 10 10 10 10 10 10 10 10 fiber base aramid fiber 6 6 6 6 6 6 6 6 6 inorganic filler graphite 2 2 2 2 2 2 2 2 2 molybdenum disulfide 3 3 3 3 3 3 3 3 3 zirconium oxide 10 10 10 10 10 10 10 10 10 zirconium silicate 1 1 1 1 1 1 1 1 1 calcium hydroxide 3 3 3 3 3 3 3 3 3 barium sulfide 20 20 10 9 20 22.5 17 28 11 calcium carbonate 12 12 12 12 12 12 12 4 21 lithium potassium 9 10 35 36 0 25 25 25 25 titanate potassium hexatitanate 16 15 0 0 25 0 0 0 0 organic filler fluorine based polymer 3 3 3 3 3 0.5 6 3 3 cashew dust 3 3 3 3 3 3 3 3 3 tire tread rubber 2 2 2 2 2 2 2 2 2 pulverized powder Total (weight %) 100 100 100 100 100 100 100 100 100

[0052] Table 1 shows the amount of the respective material contained in the friction material compositions in Embodiments 1-14 and Comparative Examples 1-4.

[0053] Firstly, the respective friction material compositions in the embodiments and the comparative examples commonly contains the phenol resin as the binder, and also about 10 weight % of the phenol resin relative to the entire amount of the friction material composition is commonly contained therein.

[0054] Secondly, the respective friction material compositions in the embodiments and comparative examples commonly contains the aramid fiber as the fiber base, and also about 6 weight % of the aramid fiber relative to the entire amount of the friction material composition is commonly contained therein.

[0055] Thirdly, the respective friction material composition in the embodiments and comparative examples commonly contains the graphite, the molybdenum disulfide, the zirconium oxide, the zirconium silicate, and the calcium hydroxide as the inorganic filler, and also about 2 weight % of the graphite, 3 weight % of the molybdenum disulfide, 10 weight % of the zirconium oxide, 1 weight % of the zirconium silicate, and 3 weight % of the calcium hydroxide are commonly contained therein relative to the entire amount of the friction material composition.

[0056] Fourthly, although the respective friction material composition in the embodiments and comparative examples commonly contains the barium sulfide and the calcium carbonate as the inorganic filler, differences exist in the amounts of the barium sulfide and the calcium carbonate, which are treated as variables. Also, differences exist in some of the friction material compositions in the embodiments and comparative examples which selectively contain the lithium potassium titanate, and the potassium hexatitanate therein.

[0057] Fifthly, the respective friction material composition of the embodiments and the comparative examples commonly contains the cashew dust and the tire tread rubber pulverized powder as the organic filler, and moreover the amount of the cashew dust contained therein is commonly about 3 weight % and the amount of the tire tread rubber pulverized powder is commonly about 2 weight % relative to the entire friction material composition.

[0058] Sixthly, the respective friction material composition of the embodiments and the comparative examples commonly contains the fluoropolymer as the organic filler therein; however, the amounts of the fluoropolymer are different, which are regarded as valuables.

[0059] In Embodiments 1-5, the amounts of the barium sulfide and the fluoropolymer contained in the friction material composition are different; however, the amounts of other materials including the calcium carbonate contained therein are same. From Embodiment 1 to Embodiment 5, the amount of the barium sulfide was reduced by 1 weight % at every embodiment from Embodiment 1 to Embodiment 5 respectively in order while the amount of fluoropolymer was increased by 1 weight % at every embodiment from Embodiment 1 to Embodiment 5 respectively in order.

[0060] Embodiments 6-9 contain different amounts of the barium sulfide and the calcium carbonate but the amounts of other materials including the fluoropolymer contained therein are same. From Embodiments 6 to Embodiment 9, the amount of the barium sulfide was reduced by 1 weight % at every embodiment from Embodiment 6 to Embodiment 9 respectively in order while amount of calcium carbonate was increased by 1 weight % at every embodiment from Embodiment 6 to Embodiment 9 respectively in order.

[0061] Embodiments 10-14 contains the different amounts of the barium sulfide, the lithium potassium titanate, and the potassium hexatitanate; however, Embodiments 10-14 contain the same amounts of other materials including the calcium carbonate and the fluoropolymer. The amounts of the barium sulfide, the lithium potassium titanate, and the potassium hexatitanate were changed without regularity.

[0062] Comparative Examples 1-4 contain the different amount of the barium sulfide, the calcium carbonate, and the fluoropolymer. Here, Comparative Examples 1-4 contain the same amount of other materials. The friction materials in Comparative Examples 1 and 2 are compared with the embodiments in Embodiments 1-5. The friction materials in Comparative Embodiments 3 and 4 are compared with the friction materials in Embodiments 6-9.

TABLE-US-00002 TABLE 2 Comparative Embodiments Examples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2 3 4 Evaluation braking effectiveness E E E G P E E E E E E E E E E F E E Result of the normal range of use braking effectiveness P G E E G P G E G G E E E G F P F P in high speed high load condition wear resistance of P G E E E P G G P G E E G G F E F F the friction material E = Excellent G = Good P = Pass F = Fail

[0063] Table 2 shows an evaluation result of the friction materials manufactured by using the friction material compositions in Embodiments 1-14 and Comparative Examples 1-4. Here, Table 2 shows the evaluation result of each and following definitions, i.e., (1) “the braking effectiveness in the normal range of use”, (2) “the braking effectiveness in high speed high load condition”, and (3) “the wear resistance of the friction material”. In addition, these evaluation results are based on the testing of the friction material of the respective embodiment and comparative example used in a rear disc brake.

[0064] For evaluating (1) “the braking effectiveness of the normal range of use”, the second effectiveness test was conducted based on JASO C406, “Passenger Car—Braking Device—Dynamometer Test Procedures”. Here, the brake was applied to the disc rotors which were rotating at 50 km/h under the fluid pressure of about 4 MPa until the rotation speed reached 0 km/h.

[0065] The respective evaluation result shown in the row of (1) “the braking effectiveness of the normal range of use” of Table 2 is based on an average friction coefficient μ after 5 brake actions, and Excellent, Good, Pass, and Fail can be defined as follows:

[0066] Excellent: 0.42 or more but less than 0.46;

[0067] Good: 0.38 or more but less than 0.42;

[0068] Pass: 0.34 or more but less than 0.38; and

[0069] Fail: less than 0.34.

[0070] When evaluating (2) “the braking effectiveness in high speed high load condition”, and (3) “the wear resistance of the friction material”, High Speed Pattern Simulation Test published in German Car Magazine, “Auto Motor Und Sport” (AMS) was performed under 150% condition by speed. Here, one brake action with the deceleration speed of 0.6 g was performed until the disc rotors rotating at 240 km/h reached the rotation speed of 5 km/h.

[0071] The respective evaluation result shown in the row of (2) “the braking effectiveness in high speed high load condition” of Table 2 is the respective evaluation result of the minimum value of an average friction coefficient μ at the final brake action, and Excellent, Good, Pass, and Fail can be defined as follows:

[0072] Excellent: 0.20 or more:

[0073] Good: 0.15 or more but less than 0.20;

[0074] Pass: 0.10 or more but less than 0.15; and

[0075] Fail: less than 0.10.

[0076] The respective evaluation result shown in the row of (3) “the wear resistance of the friction material” of Table 2 is judged based on the amount of the friction material wear after the High Speed Pattern Simulation Test, and Excellent, Good, Pass, and Fail can be defined as follows:

[0077] Excellent: less than 2.0 mm;

[0078] Good: 2.0 mm or more but less than 3.00 mm;

[0079] Pass: 3.0 mm or more but less than 4.00 mm; and

[0080] Fail: 4.0 mm or more.

[0081] Firstly, in view of the evaluation results of (1) “the braking effectiveness of the normal range of use” in the friction materials of Embodiments 1-5, all friction materials in Embodiments 1-3 are Excellent; the friction material in Embodiment 4 is Good result; and the friction material in Embodiment 5 is Pass result. Accordingly, so far as (1) “the braking effectiveness of the normal range of use” is concerned, it can be said that the evaluation is low when the amount of the fluoropolymer is large.

[0082] Secondly, in view of the evaluation result of (2) “the braking effectiveness in high speed high load condition” in the friction materials of Embodiments 1-5, the evaluation results for all friction materials in Embodiments 3 and 4 are Excellent; the evaluation results for all friction materials in Embodiments 2 and 5 are Good; and the evaluation results for the friction material in Embodiment 1 is Pass. Therefore, with respect to the evaluation result of (2) “the braking effectiveness in high speed high load condition”, it can be said that there is an adverse effect on the evaluation results when the amount of the fluoropolymer is small.

[0083] Thirdly, in view of the evaluation result of (3) “the wear resistance of the friction material” in the friction materials of Embodiments 1-5, the evaluation result for the friction material in Embodiment 1 is Pass; the evaluation result for the friction material in Embodiment 2 is Good; and the evaluation results for the friction materials in Embodiments 3-5 are Excellent. Accordingly, with respect to (3) “the wear resistance of the friction material”, it can be said that the evaluation is low when the amount of the fluoropolymer is small.

[0084] Referring to Comparative Example 1, the friction material in Comparative Example 1 shows 0.5 weight % less fluoropolymer contained therein than that of Embodiment 1. In this case, the evaluation results of both (2) “the braking effectiveness in high speed high load condition” and (3) “the wear resistance of the friction material” were Fail.

[0085] Then, referring to Comparative Example 2, the friction material in Comparative Example 2 shows 1 weight % more fluoropolymer contained therein than that of Embodiment 5. In this case, the evaluation result of (1) “the braking effectiveness of the normal range of use” was Fail.

[0086] In consideration of the above-evaluation results, it was found that the evaluation results for the friction materials in Embodiments 1-5, when the amounts of the fluoropolymer contained therein is appropriate, were Excellent with respect to all (1) “the braking effectiveness of the normal range of use”, (2) “the braking effectiveness in high speed high load condition”, and (3) “the wear resistance of the friction material”.

[0087] Furthermore, in consideration of the evaluation results of the friction materials in Comparative Examples 1 and 2, it was found that the evaluation results of the friction materials in Embodiments 1-5 all pass and satisfy the evaluation criteria when the amount of the fluoropolymer is 1 weight % or more but 5 weight % or less relative to the entire friction material composition. Especially, just like Embodiments 2-4, it can be said that the evaluation results of the friction material are Good when the amount of the fluoropolymer is 2-4 weight % relative to the entire friction material composition.

[0088] Then, referring to the evaluation results of (1) “the braking effectiveness of the normal range of use” with respect to Embodiments 6-9, all evaluation results of the friction materials in Embodiments 6-9 were Excellent.

[0089] Then, referring to (2) “the braking effectiveness in high speed high load condition” with respect to the friction materials in Embodiments 6-9, the evaluation result for the friction material in Embodiment 8 was Excellent; the evaluation results for the friction materials in Embodiments 7 and 9 were Good; and the evaluation result for the friction material in Embodiment 6 was Pass. Accordingly, it can be said that the evaluation result for (2) “the braking effectiveness in high speed high load condition” is not preferable when the amount of the calcium carbonate is small.

[0090] Then, referring to the evaluation results for (3) “the wear resistance of the friction material” with respect to Embodiments 6-9, the evaluation result for the friction materials in Embodiments 7 and 8 were Good and the evaluation results for the friction material in Embodiments 6 and 9 were Pass. Accordingly, it can be said that the evaluation result for (3) “the wear resistance of the friction material” is not preferable when the amount of the calcium carbonate is large or small.

[0091] Referring to Comparative Example 3, the friction material in Comparative Example 3 shows 1 weight % less calcium carbonate than Embodiment 6 relative to the entire amount of the friction material composition. In this case, the evaluation results for (2) “the braking effectiveness in high speed high load condition” and (3) “the wear resistance of the friction material” were Fail.

[0092] Then, referring to Comparative Example 4, the friction material in Comparative Example 4 shows 1 weight % more calcium carbonate contained therein than that of the friction material in Embodiment 9. In this case, the evaluation result for (3) “the wear resistance of the friction material” was Fail.

[0093] In consideration of the above-evaluation results, it can be said that the evaluation results for the friction materials in Embodiments 6-9, when the amounts of the calcium carbonate contained therein was appropriate, all passed and satisfied the evaluation criteria with respect to all (1) “the braking effectiveness of the normal range of use”, (2) “the braking effectiveness in high speed high load condition”, and (3) “the wear resistance of the friction material”.

[0094] Furthermore, in consideration of the evaluation results for the friction materials in Comparative Examples 3 and 4, it was found that the amount of the calcium carbonate in the friction materials in Embodiments 6-9 were preferably 5 weight % or more but 20 weight % or less. Especially, just like Embodiments 7 and 8, it can be said that the amount of calcium carbonate relative to the entire amount of friction material composition is preferably 7-8 weight %.

[0095] Then, referring to the evaluation results of (1) “the braking effectiveness of the normal range of use” with respect to Embodiments 10-14, all evaluation results with respect to Embodiments 10-14 were Excellent.

[0096] Furthermore, referring to the evaluation results for the friction materials of (2) “the braking effectiveness in high speed high load condition”, all evaluation results for Embodiments 11-13 were Excellent and all evaluation results for Embodiments 10 and 14 were Good.

[0097] Here, as examining in more detail of the evaluation results, with respect to Embodiments 10 and 11 and 14, the amount of the lithium potassium titanate and potassium hexatitanate same but the content ratio thereof are different.

[0098] More concretely, to focus on the lithium potassium titanate, the amount of the same in Embodiment 10 was 10 weight % relative to the entire friction material composition, and the amount of the same in Embodiment 11 was 9 weight % relative to the entire friction material composition. Regardless of the above-evaluation results, the evaluation result for (2) “the braking effectiveness in high speed high load condition” with respect to Embodiment 10 was Good and that with respect to 11 was Excellent.

[0099] Then, with respect to Embodiments 1-9, preferable evaluation results can be seen for (2) “the braking effectiveness in high speed high load condition” even without containing the potassium hexatitanate, and with respect to Embodiment 14, the evaluation result for the friction material was Good with relatively large amount of the potassium hexatitanate, and therefore, it can be understood that an existence of the potassium hexatitanate does not make a significant effect on the evaluation result for (2) “the braking effectiveness in high speed high load condition”.

[0100] Accordingly, it can be understood that the amount of the lithium potassium titanate affects on the evaluation result for the friction material for (2) “the braking effectiveness in high speed high load condition” and that the amount of the lithium potassium titanate contained therein is preferably 10 weight % or more relative to the entire amount of the friction material composition.

[0101] Then, referring to the evaluation results for (3) “the wear resistance of the friction material” with respect to Embodiments 10-14, all evaluation results for the friction materials in Embodiments 11 and 12 were Excellent and all evaluation results for the friction materials in Embodiments 13 and 14 were Good.

[0102] Here, as examining in more detail of the evaluation results, with respect to Embodiments 12 and 13, both embodiments do not contain the potassium hexatitanate and the amounts of the lithium potassium titanate are slightly different only.

[0103] More concretely, to focus on the lithium potassium titanate, the amount of the same in Embodiment 12 was 35 weight % relative to the entire friction material composition, and the amount of the same in Embodiment 13 was 36 weight % relative to the entire friction material composition. Regardless of the above-evaluation results, the evaluation result for (3) “the wear resistance of the friction material” with respect to Embodiment 12 was Excellent and that with respect to 13 was Good.

[0104] Furthermore, with respect to Embodiments 1-9, because the preferable evaluation result was obtained for (3) “the wear resistance of the friction material” even without containing the potassium hexatitanate, it can be said that the amount of the lithium potassium titanate contained therein is preferably 35 weight % or lower relative to the entire friction material composition.

[0105] In consideration of the above-evaluation results, the friction materials in Embodiments 10-14, assuming that the amount of the calcium carbonate is predetermined (as desired), the amount of the lithium potassium titanate relative to the entire friction material composition is preferably 36 weight % or less.

[0106] Especially, as in Embodiments 11 and 12, it can be said that the amount of the lithium potassium titanate contained therein relative to the entire amount of the friction material composition is preferably 10-35 weight %.