JPS594459B2 - Friction modifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a friction-modifying material obtained by modifying force shoe dust, which has conventionally been commonly used as a raw material for friction materials. This article relates to a new raw material that can bring out the characteristics of semi-metallic disc pads, which are being actively studied by automobile manufacturers and others for practical use.

Force has traditionally been used as a raw material for friction materials. Shoe dust is an extremely useful raw material for improving the practical life of friction materials in the temperature range up to about 200°C, which is the most frequently used practical range for brakes. Also, due to its chemical structure, crab dust has high elasticity,
For this reason, it has the effect of absorbing frictional vibrations and preventing the generation of noise5, which is a serious problem during practical walking. However, in recent years, the size of brakes has become more compact due to the miniaturization and weight reduction of automobiles, the increase in the number of automobiles that do not apply engine braking due to the spread of automatic cars, and the spread of 10 front-wheel drive cars with an increase in the weight ratio of the front wheels. The burden placed on materials is increasing, and the situation is reaching a point where conventional raw materials alone cannot cope with the burden.

In particular, in terms of heat resistance, force shoe dust generally begins to decompose at temperatures above 300°C, and at 400°C it is approximately 30~5015°C.
% weight reduction, and the reality is that it is no longer as effective as it has been in the past in dealing with the rise in brake temperature caused by the increased burden on brake materials in recent years. This tendency is particularly noticeable in semi-metallic disc pads (DP) in which asbestos is replaced with sulfur fiber or other reinforcing fibers.

In other words, in the case of semi-metallic DP, its thermal conductivity is approximately 3 to 4 times higher than that of conventional asbestos DP.
Frictional heat is also absorbed into the DP itself. For this reason, the force shoe dust contained in the semi-metallic DP hastens its decomposition due to its lack of heat resistance, and is no longer able to fully achieve the effects initially expected of the force shoe dust. 10 The present invention corrects the drawbacks of the force shoe dust and improves the heat resistance while maintaining the effects of the conventional force shoe dust.

That is, the present invention provides a friction rope containing coke powder and force shoe dust, and a friction material containing the coke powder in an amount of 40 to 100% by weight based on force shoe nut shell oil, which is the raw material for the force shoe dust. Regarding modification materials.

The friction modifier according to the present invention is made of cashew dust and coke powder, and provides heat resistance and good thermal conductivity while retaining the original functions of cashew dust.

The coke powder used in the present invention is, for example, 1100 to 12
It is made by drying coke calcined at 00°C and then finely pulverizing it between 60 mesh and 350 mesh, and its heat resistance is such that the weight loss at 800°C is 5% in the presence of air.
~10% (weight loss of 1.5% or less at 1000°C under inert gas), has extremely high heat resistance, and since it is a porous material, it retains elasticity and is resistant to heat. It is also a good conductor. The blending ratio of coke powder and cashew dust varies depending on the quality of the friction material, but the coke powder is 40 to 100% by weight, preferably 50 to 100% by weight, based on cashew nut oil, which is the raw material for cashew dust.
It is 90% by weight.

If it is less than 40% by weight, the effect of improving heat resistance is small;
If the content exceeds % by weight, the friction modification properties achieved by using cashew dust will decrease.

The friction modifier according to the present invention is produced by thermally polymerizing cashew nutshell oil in the presence of an acid catalyst such as sulfuric acid during the production process of cashew dust. Then, while an aldehyde such as formaldehyde is added and an addition condensation reaction is carried out, coke powder is added and mixed thoroughly in a kneader or the like.

The cashew dust containing coke powder thus obtained is pulverized and used. It is particularly preferable to add coke powder by mixing it with cashew nut shell oil before the thermal polymerization. In the friction modifier according to the present invention, it is preferable that individual pieces of coke powder are coated with cashew dust, and the coke powder is dispersed in the cashew dust as a whole. Next, examples of the present invention will be shown. Example 1 (l) A coke powder exhibiting the following properties was used.

Fixed carbon 86±3% Ash content 14±3 Volatile content 2% or less Particle size 60 mesh or more 5% 100〃 20 200″ 70 Add the above coke powder to carefully selected and dehydrated cashew nutshell oil. 90 of
% by weight, then added 5 parts by weight of sulfuric acid, and heated and polymerized at 160°C for 2 hours.
After adding parts by weight and mixing, heat the mixture in a heated furnace.
Heat cure at 50°C for 1 hour and at 180°C for 5 hours.

After cooling, it was pulverized to obtain a friction modifier (I) having a particle size of 40 to 80 mesh. The friction modifier produced in this manner was mixed uniformly with other materials in the formulation shown in Table 1 below, and heated and pressure molded for 5 minutes at a temperature of 150°C and a pressure of 400K9/d to form a molded product. After that, it was heated in a hot air oven at 200℃
A friction material was manufactured by heating and curing for a period of time.

Comparative Example 1 A friction material was produced according to Example 1 except that cashew dust was used instead of the friction modifier (I) in Example 1.

Example 2 (l) A coke powder having the following characteristics was used.

Fixed carbon 86±3% Ash content 14±3 Volatile content 2% or less Particle size Above 200 mesh 10% 350〃 25 Below 350″ 65 Examples except that 50 weight of the above coke powder was used with respect to cashew nut shell oil. A friction modifier () was manufactured according to 1.

(il) Using the friction modifier (□) produced in (l) above, a friction material was produced according to Example 1 with the formulation shown in Table 2 below.

Comparative Example 2 A friction material was produced according to Example 2, except that cashew dust was used instead of the friction modifier (2).

In order to investigate the heat resistance of the friction materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2, a wear test against temperature and a friction performance (friction coefficient) test were conducted.

FIG. 1 shows the measurement results of the wear amount versus temperature, and FIG. 2 shows the measurement results of the friction coefficient versus temperature.

These performance tests were carried out using an inertial type dynamometer tester, an Anett type brake caliper manufactured by Garling Co., Ltd., and an inertia of 4.5 kg-m-S2. The area of the dead sample is 37 (7i). Regarding the test results, first of all, looking at Figure 1, there is a comparison between the friction material of Example 1 (curve 1) and ordinary cashew dust added at the same blending ratio as Example 1. Comparing the amount of wear due to heat of the friction material of Example 1 (curve 2) and the friction material of Comparative Example 2 (curve 4) in which ordinary cashew dust was added to the friction material of Example 2 (curve 3). It was found that the friction materials to which the friction modifier according to the present invention was added had excellent wear resistance.
It has been proven that heat resistance can be improved by adding coke powder.
In addition, the amount of wear at a low temperature of 100°C is approximately 1/1 compared to the semi-metallic DP that does not contain cashew dust, as shown by curve 5.
2, indicating that the low-temperature wear-improving effect of cashew dust containing coke is maintained. As shown in FIG. 2, the coefficient of friction shows a similar tendency, and it can be seen that the decrease in the coefficient of friction at high temperatures due to the improved heat resistance of the modified cashew dust is very small.

In Figure 2, curve 6 is for the friction material of Example 1, curve 7 is for the friction material of Comparative Example 1, curve 8 is for the friction material of Example 2, and curve 9 is for the friction material of Comparative Example 2. It is related to. The friction modifier according to the present invention has excellent heat resistance in terms of friction coefficient and wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the amount of wear and the temperature of the friction material, and FIG. 2 is a graph showing the relationship between the coefficient of friction and the temperature. Explanation of symbols, 1, 6... Curve related to the friction material of Example 1, 2, 7... Curve related to the friction material of Comparative Example 1, 3, 8... Curve related to the friction material of Example 1 Curve related to the friction material of Example 2, 4, 9...Curve related to the friction material of Comparative Example 2.

Claims (1)

[Scope of Claims] 1. A friction modifier comprising coke powder and cashew dust, the coke powder containing 40 to 100% by weight of cashew nut shell oil, which is the raw material for the cashew dust. 2. The friction modifier according to claim 1, wherein coke powder is coated with cashew dust. 3. The friction modifier according to claim 1, wherein coke powder is dispersed in cashew dust.