JPH0739587B2 - Lubricating Silicone Grease for Synthetic Rubber Parts for Automotive Brake Systems - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lubricating silicone grease, and more particularly to a lubricating silicone grease suitable for a vehicle brake device.

<< Prior Art >> Conventionally, a synthetic rubber sliding surface lubrication grease based on a hydrocarbon mineral oil or a synthetic oil and mainly using a metal salt of various fatty acids as a thickener has been used. . However, these sliding parts materials are exposed to higher temperature conditions than before due to the trend toward higher integration and higher performance, and the operating environment tends to become more severe. This tendency is remarkable for materials for sliding parts for automobiles. In other words, the temperature of the brake parts has become remarkably high with the shift of automobile brake shoes to non-asbestos prescription from the viewpoint of pollution problems. Under such circumstances, silicone grease, which has better heat resistance than conventional non-silicone type grease, has been required as a lubricating grease for brake rubber cup parts.

<Problems to be Solved by the Invention> However, most of the silicone greases are generally thickened with a silicone oil and a metal salt of various fatty acids, particularly lithium stearate. High reactivity with various rubber compounding materials such as vulcanizing agents, vulcanization accelerators, reinforcing agents, and fillers.

Therefore, if silicone grease is simply used as a lubricating grease for brake rubber cup parts, the above thickener chemically reacts with various rubber compounding materials to form solids when the temperature of the brake rubber cup rises above 100 ° C. However, there is a drawback that it may cause malfunction.

The present inventors have conducted extensive studies to solve the above-mentioned drawbacks, and as a result, when a non-metallic powder as a thickener, especially when an organic amine-treated bentonite is used, solid matter formation occurs even at high temperatures. However, they have found that stable performance can be obtained over a long period of time, and have reached the present invention.

Therefore, a first object of the present invention is to provide a synthetic rubber sliding surface lubricating grease which has excellent heat resistance and can be used for a long period of time.

A second object of the present invention is to provide a lubricating scricone grease for a brake device for an automobile, which can obtain stable performance for a long period of time.

<< Means for Solving the Problems >> The above-mentioned objects of the present invention have the following general formulas. For 100 parts by weight of organopolysiloxane having a viscosity of 10 to 100,000 cs at 25 ° C., and 2 to 70 parts by weight of bentonite treated with organic amine, for a synthetic rubber part for an automobile brake device. Achieved by lubricating silicone grease.

The organopolysiloxane used in the present invention has a viscosity at 25 ° C. of 10 to 100,000 cs and is represented by the following general formula.

In the formula, R is one or more groups selected from saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms.

Specific examples of R include methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group,
Examples thereof include saturated hydrocarbon groups such as tetradecyl group and unsaturated hydrocarbon groups such as vinyl group, phenyl group and chlorophenyl group. Of these, a methyl group, a phenyl group and an alkyl group having 6 to 14 carbon atoms are particularly preferable. If the viscosity of the above organopolysiloxane at 25 ° C is less than 10cs, a smooth and extensible grease cannot be obtained.
If it is larger than this, the sliding resistance of the grease becomes large, and the performance as grease cannot be fully exhibited. Therefore, in the present invention, the range of 100 to 10,000 cs is particularly preferable.

In the present invention, bentonite treated with an organic amine is particularly used as a thickener.

The amount of the thickening agent used is 100 parts by weight of the organopolysiloxane, preferably 2 to 70 parts by weight, more preferably 5 to 65 parts by weight. If it is less than 5 parts by weight, the grease is soft,
Also, if the amount is more than 65 parts by weight, the grease will become hard, so
65 parts by weight is preferred.

In the lubricating silicone grease of the present invention, even if an antioxidant is added as necessary for the purpose of improving heat resistance, an extreme pressure additive or oiliness improver for the purpose of improving lubricity, or rust preventive against metal For this purpose, a rust preventive agent or the like may be added.

The method for producing a lubricating silicone grease applied to the automobile brake device of the present invention is such that the organopolysiloxane as the first component and the thickener as the second component are calculated in a mixer such as a planetary mixer, Accordingly, the third component is further added and mixed. The mixing may be performed under heating.

In the present invention, after the mixing, a kneading operation for uniform finishing is further performed. As a kneading device, there are three rolls, a colloid mill, a sand grinder, a gaurin homogenizer, and the like, but the three roll method is particularly preferable.

<Effects of the Invention> The lubricating silicone grease of the present invention uses various rubber compounding materials and non-reactive organic amine-treated bentonite as a thickener, so that it is used in places with high temperatures such as automobile braking devices. Even so, it has sufficient durability and can maintain stable performance for a long period of time.

<Example> Next, the present invention will be further described with reference to examples, but the present invention is not limited thereto. In addition, the measurement of the mixing consistency in the examples is at 25 ° C., and JIS-K
-Measured according to 2202 "Grease". The heat resistance test of synthetic rubber is performed by immersing the rubber in grease, and various characteristics of grease as a rubber lubricant are evaluated by JIS-K-2228.
The measurement was performed according to "Non-mineral oil type rubber lubricant for automobile brakes".

Example 1 and Comparative Examples 1 to 3 As shown in Table 1, organopolysiloxane as a base oil and a thickener were weighed into a planetary mixer,
After mixing well for 30 minutes, kneading was performed three times using a triple roll. However, when the Li-soap-based thickener of Comparative Example was used, heat treatment was indispensable, and therefore heat treatment was performed at 185 ° C./2 hours during mixing.

Regarding the obtained lubricating silicone grease, JIS-K-2
Consistency is measured in accordance with the provisions of 220, and it is determined with the SBR rubber cup for wheel cylinders (diameter 1 (1/8) inch) conforming to JIS-D-2605-2 immersed in grease. The results of evaluating the heat resistance of the grease by visually observing the presence or absence of solids formed on the surface of the SBR rubber cup after heating for an hour are also shown in Table 1.

From the results in Table-1, it was demonstrated that the lubricating silicone grease of the present invention has extremely good heat resistance.

Example 2 The lubricating silicone grease of Sample No. 1 of the present invention produced in Example 1 was evaluated for various characteristics when used in a vehicle brake device according to JIS-K-2228. The results are shown in Table-2. From these results, it was demonstrated that the lubricating silicone grease of the present invention can maintain stable lubricating performance for a long period of time even when contacting with the SBR rubber at high temperature.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C10N 40:00 Z 50:10 (72) Inventor Satoshi Kuwata 2-13- Isobe, Gunma Prefecture 1 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) Reference JP 63-275696 (JP, A) JP 63-235398 (JP, A) JP 59-157192 (JP, A) JP-A-56-82894 (JP, A) JP-B-45-20794 (JP, B1)

Claims (1)

[Claims] 1. The following general formula (Wherein R is one or more groups selected from saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms), and the viscosity at 25 ° C. is 10 to 10 Ten thousand
Lubricating silicone grease for synthetic rubber parts for automobile braking devices, which comprises 100 parts by weight of cs organopolysiloxane and 2 to 70 parts by weight of organic amine-treated bentonite.