Friction material

Abstract

To provide a frictional material with improved wear resistance.MEANS FOR SOLVING THE PROBLEM: Provided is a friction material comprising, as main components, a fiber material, a binder, a lubricant, and a friction modifier, where the binder is an aralkyl-modified phenol resin, the lubricant comprises flaky graphite and granular graphite. In a range where the total amount of the flaky graphite and the granular graphite becomes 11 wt.% or less relative to the total amount of the composition, the flaky graphite is contained in an amount of 1.5-3.0 wt.% and the granular graphite is contained in an amount of 7.0-8.5 wt.%.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to friction materials used in brake shoes and brake pads for vehicles such as automobiles and motorcycles, and in particular to improvements in friction materials whose main components are fiber materials, binders, lubricants, and friction modifiers. [Background technology]

[0002] Among such friction materials, Patent Document 1 below describes one that contains at least two types of graphite particles with different particle sizes as a lubricant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-109369 Summary of the Invention [Problem to be solved by the invention]

[0004] The friction material described in Patent Document 1 contains at least two types of graphite particles with different particle sizes, which allows for improved wear resistance while reducing the graphite content, but insufficient consideration has been given to its resistance to wear during braking.

[0005] Here, "pull-off" during braking refers to the phenomenon that occurs when, for example, a disc brake is operated under wet and high load conditions, the braking heat causes the organic components and moisture inside the friction pad, i.e., the friction material, to evaporate, causing swelling on the surface of the friction pad, and the swollen surface is then peeled off and roughened by the numerous holes in the disc rotor.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a friction material with excellent resistance to abrasion. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a friction material whose main components are a fiber material, a binder, a lubricant, and a friction modifier, wherein the binder is an aralkyl-modified phenol resin, and the lubricant contains flake graphite and granular graphite, The friction modifier contains copper powder The first feature of this friction material is that it contains 1.5 to 3.0 Wt% of the scaly graphite and 7.0 to 8.5 Wt% of the granular graphite, with the total amount of the scaly graphite and granular graphite being within a range of 11 Wt% or less of the total composition of the friction material.

[0008] In addition to the first feature, the present invention is characterized in that the average particle size of the granular graphite is 300 to 600 μm, the average particle size of the flake graphite is 180 to 220 μm, and the fiber material contains copper fibers. ,child The second feature of the friction material is that it contains 4.0 to 7.5 wt% of the copper fibers and 20.0 to 2.0 wt% of the copper powder, with the total amount of the copper fibers and copper powder being within a range of 35.0 wt% or less of the total composition of the friction material, and the friction material further contains brass powder.

[0009] Furthermore, in addition to the second feature, the present invention has the following features: scale 2.0 to 2.5 wt% of the above-mentioned graphite grain The third feature is that the composite material contains 8.0 to 8.5 wt% of crystalline graphite, 4.5 to 6.0 wt% of the copper fibers, and 22.0 to 25.0 wt% of copper powder. [Effects of the Invention]

[0010] According to the first feature of the present invention, the surface of the friction material can be strengthened, and its resistance to tearing can be improved.

[0011] According to the second feature of the present invention, it is possible to improve the wear resistance and braking effectiveness of the friction material while maintaining the resistance to tearing of the friction material.

[0012] According to the third feature of the present invention, it is possible to further improve the wear resistance and braking effectiveness of the friction material while maintaining the resistance to abrasion of the friction material. [Brief explanation of the drawings]

[0013] [Figure 1] The composition ratios of the conventional friction material, the friction material according to the present invention, and the comparative examples 1 to 3 are shown in Table 1. [Figure 2] 1 is a diagram showing the results of a test comparing braking performance between a conventional friction material and the friction material of Example 1 of the present invention. [Figure 3] 1 is a comparison diagram showing the results of a wear resistance comparison test between a conventional friction material and the friction material of Example 1 of the present invention. [Figure 4] Photographs showing the results of a test comparing the resistance to abrasion between a conventional friction material and the friction material of Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The friction material according to the present invention is applied to, for example, brake pads attached to vehicle disc brakes.

[0015] In Table 1 of FIG. 1, in the friction materials of Examples 1 to 15 of the present invention, an aralkyl-modified phenol resin was used instead of the straight phenol resin of the conventional example.

[0016] In addition, in the friction materials of Examples 1 to 15 of the present invention, the composition ratio of flaky graphite is set to 1.5 to 3.0 Wt%, instead of 7.5 Wt% in the conventional examples, and the composition ratio of granular graphite is set to 7.0 to 8.5 Wt% in Example 1, instead of 5.0 Wt% in the conventional examples, and the total amount of flaky graphite and granular graphite is set to 11 Wt% or less of the total composition amount of this friction material.

[0017] Furthermore, in the friction materials of Examples 1 to 8, in addition to the above, The composition ratio of copper powder is The composition ratio of copper fiber was set to 20.0 to 27.0 Wt%, and the composition ratio of copper fiber was set to 4.0 to 7.5 Wt%, and the total amount of copper fiber and copper powder was set to 35 Wt% or less with respect to the total composition amount of this friction material.

[0018] Here, we will explain the "test items" in Table 1.

[0019] "Braking effectiveness" was determined by conducting a braking test using dry friction material in a vehicle running mode at 50 km / h on a bench test machine, measuring the friction coefficient of the friction material and judging braking effectiveness performance. Effectiveness values ​​within ±10% of the conventional value were rated as the best (◎), those within ±20% were rated as good (○), and those outside the ±20% range were rated as poor (×).

[0020] "Wear resistance" was determined by measuring the amount of wear on the friction material on a bench test machine under various braking modes (similar conditions to those in Figure 3 below) and making a comprehensive judgment. An extremely small amount of friction was rated as the best: "◎", a small amount was rated as good: "○", and a large amount was rated as poor: "×".

[0021] "Pull-resistant performance" is measured on a bench test machine by braking the vehicle at 80km / h with water-sprayed friction material, causing the vehicle to decelerate by 4m / s. s 2 ,6m / s 2 ,8m / s 2 When the friction material was subjected to the test, the presence or absence of peeling was observed and judged; if peeling was observed, it was rated as "present," and if not, it was rated as "absent."

[0022] 2 is a diagram showing the braking performance of the conventional friction material and the friction material of Example 1. As can be seen from this diagram, both the conventional friction material and the friction material of Example 1 exhibit good braking performance.

[0023] 3 is a diagram showing the wear resistance of the friction material of the conventional example and the friction material of Example 1. As can be seen from this diagram, both the friction material of the conventional example and the friction material of Example 1 have good wear resistance.

[0024] In Figure 3, "low-temperature braking" refers to the braking state when the vehicle speed is 50 km / h and the friction material temperature is 50°C, "first braking" refers to the braking state when the vehicle speed is 50 km / h and the friction material temperature is 80°C, "second braking" refers to the braking state when the vehicle speed is 80 km / h and the friction material temperature is 120°C, "third braking" refers to the braking state when the vehicle speed is 120 km / h and the friction material temperature is 150°C, and "high-speed braking" refers to the braking state when the vehicle speed is 150 km / h and the friction material temperature is 250°C.

[0025] 4 is a set of photographs showing the results of the abrasion resistance test of the conventional friction material and the friction material of Example 1. As can be seen from these photographs, a abrasion phenomenon occurred on the surface of the conventional friction material, whereas no abrasion phenomenon was observed on the surface of the friction material of Example 1.

[0026] From the results in Table 1 above, it can be seen that in Examples 1 to 15, aralkyl-modified phenol resin was used instead of the straight phenol resin used in the conventional examples, the composition ratio of flaky graphite was set to 1.5 to 3.0 Wt% instead of 7.5 Wt% used in the conventional examples, the composition ratio of granular graphite was set to 7.0 to 8.5 Wt% instead of 5.0 Wt% used in the conventional examples, and the total amount of flaky graphite and granular graphite was set to 11 Wt% or less. This not only formed a strong surface on the friction material, but also ensured an escape route for gases and water vapor generated inside the friction material when heated to high temperatures, thereby improving the resistance to wear of the friction material as described above.

[0027] Furthermore, as in Examples 1 to 8, the average particle size of the granular graphite was set to 300 to 600 μm, the average particle size of the flaky graphite was set to 180 to 220 μm, copper fiber was selected as the fiber material, and copper powder was selected as the friction modifier, and the composition ratio of the copper fiber was set to 4.0 to 7.5% and the composition ratio of the copper powder was set to 2.0 to 27.0% within a range in which the total amount of these copper fibers and copper powder was 35.0% or less of the total composition of the friction material, and further brass powder was added to the friction material, thereby it was recognized that wear resistance and braking effectiveness could be improved while maintaining good tear resistance performance.

[0028] Furthermore, as in Examples 1 to 4, with respect to the total composition amount of the friction material, scale The composition ratio of graphite is 2.0 to 2.5 Wt%, grain By setting the composition ratio of graphite to 8.0 to 8.5 Wt%, the composition ratio of copper fiber to 4.5 to 6.0 Wt%, and the composition ratio of copper powder to 22.0 to 25.0 Wt%, it is recognized that wear resistance and braking performance have been further improved while maintaining good resistance to tearing.

[0029] In summary, the noteworthy point of this invention is that aralkyl-modified phenol resin is selected as the binder, and flake graphite and granular graphite are selected as the lubricant, and the total amount of flake graphite and granular graphite is 11 wt% of the total amount of the friction material. below Within this range, the composition ratio of flake graphite should be set to 1.5 to 3.0 wt%, and the composition ratio of granular graphite should be set to 7.0 to 8.5 wt%, which will improve the resistance to wear of the friction material.

[0030] Furthermore, in addition to the above, it is noteworthy that the average particle size of the granular graphite is set to 300 to 600 μm, the average particle size of the flaky graphite is set to 180 to 220 μm, copper fiber is selected as the fiber material, and copper powder is selected as the friction modifier, and the total amount of these copper fiber and copper powder is 35.0% of the total amount of the friction material composition. Wt The composition ratio of copper fiber is 4.0 to 7.5% or less. Wt %, the composition ratio of copper powder is 20.0 to 27.0 Wt %, and the friction material contains brass powder. This makes it possible to improve wear resistance and braking performance while maintaining good resistance to wear on the surface of the friction material. In this case, the total amount of the friction material is scale The composition ratio of graphite is 2.0 to 2.5 wt%, grain By setting the composition ratio of crystalline graphite to 8.0 to 8.5 wt%, the composition ratio of copper fiber to 4.5 to 6.0 wt%, and the composition ratio of copper powder to 22.0 to 25.0 wt%, it is possible to further improve the wear resistance and braking performance while maintaining good resistance to abrasion of the friction material surface.

[0031] Thus, according to the composition ratios of Examples 1 to 4, the braking effect, abrasion resistance and tear resistance of the friction material can all be fully satisfied.

[0032] Furthermore, based on the composition ratios of Examples 5 to 8, the test results indicated that the friction material's resistance to ripping was "absent," and the braking effectiveness and friction resistance were judged to be "good" or better. Therefore, the friction material's braking effectiveness, friction resistance, and ripping resistance are all satisfactory.

[0033] Furthermore, based on the composition ratios of Examples 9 to 15, the test results showed that at least the friction material's resistance to ripping could be judged as "absent," and one of braking effectiveness and friction resistance could be judged as "good," but the other was judged as "poor." Therefore, the composition ratios of Examples 9 to 15 can be adopted for friction materials that emphasize either resistance to ripping or braking effectiveness and friction resistance.

[0034] Furthermore, the test results indicated that the friction material's resistance to abrasion was "present" when using the composition ratios of Comparative Examples 1 to 3. Therefore, in the present invention, which places importance on abrasion resistance, the composition ratios of Comparative Examples 1 to 3 cannot be adopted.

[0035] In Comparative Example 1, the braking effect was "poor" because the amount of graphite was excessive. Also, the resistance to ripping was "present" because the amount of scaly graphite and granular graphite was excessive.

[0036] In Comparative Example 2, the reason why the abrasion resistance was "poor" was because the amount of graphite was too small. Also, the reason why the peeling resistance performance was "present" was because the amount of scaly graphite and granular graphite was too large.

[0037] In Comparative Example 3, the reason why the peeling resistance performance showed a "yes" peeling phenomenon was because straight resin was included as a binder.

[0038] The allowable range of the composition ratio of the friction material of the present invention in Table 1 was determined by taking the above results into consideration and ensuring that at least the tear resistance performance of the friction material is satisfied.

[0039] Therefore, the above-mentioned Examples 1 to 15 correspond to the description of claim 1 of the present invention, the above-mentioned Examples 1 to 8 correspond to the description of claim 2 of the present invention, and the above-mentioned Examples 1 to 4 correspond to the description of claim 3 of the present invention.

[0040] The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various design changes can be made without departing from the present invention as described in the claims.

Claims

1. In friction materials whose main components are fiber materials, binders, lubricants, and friction modifiers, the binder is an aralkyl-modified phenolic resin, The lubricant includes flake graphite and granular graphite, The friction modifier comprises copper powder, The friction material is characterized in that it contains 1.5 to 3.0 Wt% of the scaly graphite and 7.0 to 8.5 Wt% of the granular graphite, with the total amount of the scaly graphite and granular graphite being within a range of 11 Wt% or less relative to the total composition of the friction material.

2. 2. The friction material according to claim 1, The average particle size of the granular graphite is 300 to 600 μm, The average particle size of the flake graphite is 180 to 220 μm, the fibrous material comprises copper fibers; The friction material contains 4.0 to 7.5 wt% of copper fibers and 20.0 to 27.0 wt% of copper powder, with the total amount of the copper fibers and copper powder being 35.0 wt% or less relative to the total composition of the friction material, The friction material further comprises brass powder.

3. The friction material according to claim 2, The friction material is characterized in that it contains, relative to the total amount of the friction material, 2.0 to 2.5 wt% of the flake graphite, 8.0 to 8.5 wt% of the granular graphite, 4.5 to 6.0 wt% of the copper fibers, and 22.0 to 25.0 wt% of the copper powder.

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