JP2000213578A - Wet friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit sufficient durability in harsh environment without impairing a friction characteristic by forming wet friction material using paper base material containing latex, and setting the content of latex in the paper base material into a specified range. SOLUTION: A clutch disc 1 of a wet friction clutch is composed of an annular core member 2 formed of a steel plate or an Al alloy, and annular wet friction material 3 bonded to both annular surfaces of the core member 2. A plurality of oil grooves 4 extending from the inner peripheral edge to the outer peripheral edge are radially formed at the friction material 3. The wet friction material 3 is formed by impregnating thermosetting resin in paper base material and hardening it. The paper base material is formed by normal paper making work using fiber (organic fiber and/or inorganic fiber), a filler and latex, and the content CL of latex in the paper base material is set into a range of 0.4 wt.%<=CL<25 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wet friction material used for a wet friction clutch, a wet friction brake and the like.

[0002]

2. Description of the Related Art Conventionally, as a wet friction material of this type, a paper base by papermaking having various fibers and fillers,
A material composed of a thermosetting resin in which the paper base material is impregnated and cured is known.

[0003]

In recent years, with the reduction in size and weight of wet friction clutches and the like, the wet friction material has a high load,
Although it is required to have sufficient durability under high surface pressure, the problem that conventional wet friction materials cannot sufficiently meet such requirements in terms of durability under such severe conditions. was there.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a wet friction material capable of exhibiting sufficient durability under the above-mentioned severe conditions without impairing the excellent friction characteristics of a conventional wet friction material. The purpose is to provide materials.

[0005] To achieve the above object, according to the present invention,
Comprising a paper substrate comprising a latex content of the latex in the paper substrate C _L is 0.4 wt% ≦ C
A wet friction material with _L <25 wt% is provided.

[0006] With the above construction, since the latex functions as a binder for binding fibers and the like to each other in the paper base material, the strength of the paper base material is increased, and as a result, the wet friction material under severe conditions is used. Durability can be greatly improved. Also, the latex content C _L
Within the above range, the porosity of the wet friction material is not impaired, and therefore, its excellent friction characteristics can be secured.

[0007] In order to make the durability of the wet friction material remarkably improved, it is necessary that the strength of the paper base material be about 5.5 MPa or more in tensile strength. The lower limit of the content C _L of the latex is C _L =
Limited to 0.4 wt%. On the other hand, when C _L ≧ 25 wt%, the μs / μd value becomes large, and the friction characteristics of the wet friction material are reduced.
In the clutch, the judder characteristic tends to decrease.

[0008]

1 and 2, a clutch disc 1 of a wet friction clutch comprises an annular core member 2 made of a steel plate or an Al alloy and two annular wet friction members adhered to both annular surfaces thereof. And 3. Both friction members 3 have a plurality of oil grooves 4 extending from the inner peripheral edge to the outer peripheral edge.

The wet friction material 3 comprises a paper substrate and a thermosetting resin impregnated and cured in the paper substrate.

[0010] The paper base material is formed by a usual paper-making operation using a raw material liquid containing fibers, that is, organic fibers and / or inorganic fibers, a filler, and latex.

As organic fibers, linter pulp, aramid fibers and the like are used. As inorganic fibers, carbon fibers and glass fibers are used. As fillers, silica, cashew dust, rubber powder, activated carbon and the like are used.

As the latex, natural rubber latex, synthetic rubber latex, synthetic resin emulsion and the like are used. Latex content C _L in paper substrate
It is set to _{0.4wt% ≦ C L <25wt%} .

[0013] When the latex is contained in the paper base as described above, the latex functions as a binder for binding fibers and the like to each other, so that the strength of the paper base is increased. The durability of the material 3 can be greatly improved. Also by to keep the content of C _L of the latex within the range, without compromising the porosity of the wet friction material 3, thus it is possible to ensure the excellent friction characteristics.

In order to improve the binder function of the latex, it is an effective means to add a vulcanizing agent such as zinc white and a vulcanization accelerator to the latex.

As the thermosetting resin, a phenolic resin is generally used, but a melamine resin, an epoxy resin or the like can also be used. The content C _R of the thermosetting synthetic resin in the wet friction material 3 is set to 15 wt% ≦ C _R <40 wt%. In this case, when C _R <15 wt%, sufficient shape-retaining property and bonding property of the thermosetting synthetic resin cannot be obtained. On the other hand, when C _R ≧ 40 wt%, the friction characteristics deteriorate.

Hereinafter, specific examples will be described.

Table 1 shows the composition of the main part of the paper substrate.

[0018]

[Table 1]

In Table 1, silica was used as a filler.

Table 2 shows the composition of the paper base material for Examples 1 to 3 and Comparative Examples 1 and 2 of the wet friction material 3.

[0021]

[Table 2]

In Examples 1 to 3 and Comparative Example 2, the content of the paper substrate was set to 70% by weight, and the content of the phenolic resin was set to 30% by weight.

Dumbbell-shaped test pieces were punched out of the paper base materials of Examples 1 to 3 and Comparative Examples 1 and 2 shown in Table 2, and the test pieces were subjected to a tensile test.
FIG. 3 shows the relationship between the content of synthetic rubber latex and the tensile strength for Examples 1 to 3 and Comparative Examples 1 and 2. Than 3, the content of C _L of the synthetic rubber latex C _L ≧ 0.
It can be seen that when the content is set to 4 wt%, the tensile strength of the paper base material is gradually increased beyond the minimum required tensile strength of about 5.5 MPa. In this case, the paper substrate of Comparative Example 1 is:
Since it does not contain synthetic rubber latex, it corresponds to the conventional example.

Next, three types of clutch discs 1 provided with the wet friction material 3 of Example 2 and Comparative Examples 1 and 2 will be described.
The μs / μd value (average value) was determined as a friction characteristic of each wet friction material 3 by performing a measurement test. In the measurement test, the clutch disk 1 was assembled in a well-known inertial absorption type clutch full size tester, and the flywheel was rotated at an input rotation speed of 2111 rpm using SAE10W30 for a 4-cycle gasoline engine as test oil. A method was adopted in which the inertial rotation of the wheel was stopped by continuing the clutch, μs and μd were measured, and the measurement was performed 300 times.

Table 3 shows the content of synthetic rubber latex and μs for wet friction material 3 of Example 2 and Comparative Examples 1 and 2.
/ Μd value (average value).

[0026]

[Table 3]

As is apparent from Table 3, Example 2 The content C _L is set to C _L = 3.0 wt% of the synthetic rubber latex, Comparative Example corresponds to the conventional example 1 and the same .mu.s / mu
has a d value, C _L = In 25.0 wt% which is set to a comparative example 2 it can be seen that .mu.s / [mu] d value becomes large as compared with Example 2 and the like.

The wet friction material according to the present invention can be applied to a wet friction brake and the like.

[0029]

According to the present invention, by adopting the above-described means, sufficient durability under severe conditions can be obtained without impairing the excellent friction characteristics of the conventional wet friction material. A wet friction material that can be exhibited can be provided.

Further, the elasticity of the wet friction material increases with the inclusion of the latex, so that the aggressiveness of the wet friction material such as abrasion of the rubbing member can be reduced.

Further, since the latex swells with oil, the amount of swelling compensates for the abrasion of the wet-type friction material, thereby suppressing an increase in the gap between the wet-type friction material and the rubbing member, thereby improving the operation feeling. Changes can be minimized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a clutch disk.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a graph showing the relationship between the content of synthetic rubber latex in a paper substrate and tensile strength.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clutch disk 2 Core material 3 Wet friction material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Suzuki, Inventor FCC Research Institute, 46, 7000 Nakagawa, Hosoe-cho, Husa-gun, Shizuoka Prefecture (72) Keiko Suzuki, Inventor Keiko Suzuki, Hosoe-cho, Shizuoka Within the FCC Technology Research Institute, 46 shares at 7000 Nakagawa (72) Inventor Kazuma Matsushita F-term in the 46th FCC Technology Research Institute, 46, Nakasagawa, Hosoe-cho, Husa-gun, Shizuoka 3J058 BA41 BA73 EA03 EA08 GA01 GA12 GA54 GA62 GA67 GA73 GA92 GA93 GA94 4F071 AA09 AA10 AA41 AA56 AB03 AB18 AB26 AB28 AE02 AH09 EA05

Claims (1)

[Claims] [Claim 1, further comprising a paper substrate comprising a latex, a wet friction material, wherein the content C _L of the latex in the paper substrate is _{0.4wt% ≦ C L <25wt%} .