JPH06306186A - Friction material - Google Patents

Abstract

PURPOSE:To obtain the material improved in both heat resistance and abrasion resistance. CONSTITUTION:The material contains a silicon-modified phenolic resin as a binder and a carbonaceous filler treated with a titanate or a silane. Because this material contains the above-specified binder, the heat resistance and the cracking resistance after a heat history can be improved. Because the treated carbonaceous filler can improve the bonding force with a binder, the abrasion resistance does not lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used as a clutch facing, a brake pad, etc. for automobiles, industrial machines, railway vehicles and the like.

[0002]

2. Description of the Related Art Performances required of friction materials include excellent wear resistance, high friction coefficient, and stable friction coefficient. A single material is difficult to satisfy these performances, and the friction material is composed of a composite material in which many materials are mixed.

As a friction material for automobiles, for example, a semi-mold type or resin mold type friction material is often used. When manufacturing such a friction material, a mixing step of mixing raw material powders and raw material fibers is performed, but it is difficult to mix raw materials having different specific gravities, particle shapes and sizes without segregation by simple dry mixing. . Therefore, conventionally, liquid raw materials such as an organic solvent, a phenol derivative, a liquid phenol resin, and a liquid epoxy resin are used as a mixing aid to prevent segregation. In addition, JP-A-2-133431
JP-A-2-133432 and the like disclose examples in which a modified phenol resin obtained by modifying an oxygen-containing oligomer having a 3-substituted aromatic hydrocarbon bonded with phenol is used as a mixing aid.

However, when an organic solvent is used as a mixing aid, various adverse effects due to gasification occur when the organic solvent is present during thermoforming, and a drying step is required before thermoforming, resulting in a large number of steps. . Further, the phenol derivative is not preferable because it causes a rash on contact with the skin. Further, the liquid phenol resin or epoxy resin remains in the friction material and causes deterioration of performance such as deterioration of fade resistance.

[0005]

In order to improve the above-mentioned problems, it is necessary to add a modified silicone oil or modified silicone rubber which reacts with a phenol resin as a binder and becomes a part of a friction material base material as a mixing aid. Is being considered. Since such modified silicone oil and modified silicone rubber are liquid and have lubricity, they prevent aggregation of the powders when they adhere to the raw material powder, and are therefore extremely effective as a mixing aid. Further, since there is no problem such as a rash on the human body, it is easy to handle.

The modified silicone oil has good thermal stability and does not gasify even when the phenol resin is cured, so that a drying step is not necessary. Further, since the functional group of the modified silicone oil reacts with the phenol resin and becomes a part of the friction material base material, there is no problem that the fade resistance is lowered. Furthermore, since the modified silicone oil also has water repellency, it is expected to eliminate the problem caused by moisture absorption.

However, in a friction material formed by using modified silicone oil or modified silicone rubber as a mixing aid, the silicone-modified phenolic resin formed improves heat resistance but deteriorates wear resistance. There was a problem. Further, when a straight phenol resin or a phenol resin modified with an organic substance is used as the binder, the heat resistance is insufficient, and cracks may occur when subjected to a strong heat history.

The present invention has been made in view of such circumstances, and an object thereof is to improve both heat resistance and abrasion resistance.

[0009]

The friction material of the present invention for solving the above-mentioned problems is characterized by containing a silicone-modified phenolic resin as a binder and a titanate-treated or silane-treated carbon-based filler. The silicone-modified phenol resin may be one formed by mixing a modified silicone oil or the like with a straight phenol resin at the time of manufacturing a friction material and binding them during heat molding, or may be one added as a silicone-modified phenol resin. .

For example, as the modified silicone oil,
R ₁ and R _{2 of} the silicone oil represented by the formula:
It is possible to use one having a functional group such as an epoxy group, a carboxyl group or a hydroxyl group, which bonds to a phenol resin, at at least one position of R ₃ . The appropriate addition amount is 0.1 to 5% by weight based on the whole friction material. If it is less than this range, the effect cannot be obtained, and if it is too large, the effect is saturated and the fade resistance is lowered due to the remaining of the modified silicone oil which has not reacted with the phenol resin.

[0011]

[Chemical 1]

This modified silicone oil can be added at the same time when the friction material raw materials are mixed. 2 in this case
It is preferable to use it in the range of 5 wt%. Further, in order to prevent only segregation of a specific powder such as cashew dust, it is preferable that modified silicone oil is attached to cashew dust in advance and then mixed with another friction material raw material. In this case, the amount of the modified silicone oil may be extremely small, and can be, for example, 1% by weight or less based on the whole friction material.

The titanate-treated or silane-treated carbon-based filler refers to graphite, coke, carbon black, carbon fiber or the like treated with an organic titanate compound or an organic silane compound. This carbon-based filler is preferably contained in the range of 0.5 to 8% by volume of the entire friction material. Content is 0.5% by volume of the whole friction material
If it is less, the abrasion resistance is not improved, and even if it is added in excess of 8% by volume, the effect is saturated and other physical properties are adversely affected.

As another component of the friction material, for example, an organic fiber such as aramid fiber, cellulose or acrylic fiber is used.
~ 15% by volume, 5-15% by volume of inorganic fibers such as carbon fiber, glass fiber, rock wool, etc., 1-7% by volume of copper or copper-based fibers and powders, lubrication of molybdenum disulfide, antimony trisulfide, etc. The agent can be used in an amount of 0.5 to 8% by volume, and other friction modifiers such as cashew dust and an abrasive agent can be used in the same manner as in the past.

[0015]

In the friction material of the present invention, since the silicone-modified phenol resin is contained as the binder, the heat resistance is improved and the crack resistance after heat history is improved. In addition, as compared with the case where a straight phenol resin or a phenol resin modified with an organic substance is used as the binder, the bond strength with the carbon-based filler is generally weak when the silicone-modified phenol resin is used. However, in the present invention, since the carbon-based filler is treated with titanate or silane, it is presumed that the bond strength with the binder is improved and the abrasion resistance is improved.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) As shown in Table 1, 10% by volume of aramid fiber, 10% by volume of slag wool, 10% by volume of potassium titanate fiber, 20% by volume of silicone rubber-modified phenol resin (manufactured by Mitsui Toatsu Co., Ltd.) , 15% by volume of cashew dust, 4% by volume of organic titanate modified graphite, 2% by volume of molybdenum disulfide, 4% by volume of copper fiber, 6% by volume of mica, 16% by volume of barium sulfate and 3% by volume of slaked lime, 16
The friction material of this example was manufactured by thermoforming at 0 ° C. (Example 2) The same as Example 1 except that 4% by volume of organosilane-modified graphite was used instead of the organic titanate-modified graphite. (Comparative Example 1) The same as Example 1 except that 4% by weight of untreated graphite was used instead of the organic titanate-modified graphite. (Comparative Example 2) The same as Example 1 except that 20% by volume of straight phenol resin was used in place of the silicone rubber-modified phenol resin and 4% by weight of untreated graphite was used in place of the organic titanate-modified graphite. . (Comparative Example 3) The same as Example 1 except that 20% by volume of a straight phenol resin was used instead of the silicone rubber-modified phenol resin. (Test / evaluation) For each of the above friction materials, PD5
1-18V caliper, inertia In = 4.5kgmS
^Under the condition of ² , braking at 50 → 0 km / h × 0.3 G,
The wear rate was measured at two levels of the braking temperature before braking: 200 ° C and 300 ° C.

Further, the presence or absence of cracks in the appearance after performing the first fade test and the second fade test of JASO under the conditions of PD51-18V caliper and inertia In = 5.0 kgmS ² was examined to check for cracks. The appearance was evaluated as x after heat history, and the one without crack was evaluated as o. The respective results are shown in Table 1.

[0018]

[Table 1]

From Table 1, looking at Comparative Example 1 and Comparative Example 2,
Comparative Example 1 using a silicone rubber modified phenolic resin
Is a comparative example 2 in which the heat resistance is free from the occurrence of cracks after heat history.
It is understood that the abrasion resistance is reduced though it is improved compared to. On the other hand, it can be seen that the friction material of the example has improved wear resistance particularly at high temperature as compared with the conventional friction material of comparative example 2, and significantly improved as compared with comparative example 1. Further, it is clear that the cracks after the heat history are the same as in Comparative Example 1 and are improved as compared with Comparative Example 2. Since there is no difference between the results of Comparative Example 2 and Comparative Example 3, there is no effect even if only the organic titanate modified graphite is used without using the silicone rubber modified phenolic resin, and the silicone rubber modified phenolic resin and the organic titanate modified graphite are not used. It is also clear that the effect is exhibited only when and are used together.

[0020]

According to the friction material of the present invention, both heat resistance and abrasion resistance are improved, so that it has a long life and can be used under more severe conditions. Becomes higher.

Claims (1)

[Claims] 1. A friction material comprising a silicone-modified phenolic resin as a binder and a titanate-treated or silane-treated carbon-based filler.