JPH0455499A - Hydraulic fluid composition of liquid pressure brake for automobile - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent corrosion resistance in a break system and suppressing the generation of precipitation by adding a specific amount of a specific nitrogen-containing compound as a precipitation inhibitor to a non-mineral-based hydraulic fluid. CONSTITUTION:A nitrogen-containing compound as a precipitation inhibitor expressed by formula I and/or formula II [R1 and R2 are H or phenol; (n) is 0 or integer of 1-3 (preferably 0); (m) is 0 or integer of 1-4 (preferably 3)] is added to a non-mineral-based hydraulic fluid in an amount of >=0.005 wt.% (preferably 0.01-0.1 wt.%) to afford the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic brake hydraulic fluid composition for automobiles, and particularly to a hydraulic fluid that has excellent anticorrosion properties and suppresses the formation of precipitates in brake systems.

(Prior Art) Quality requirements for recent automobiles have become more and more sophisticated, and in response, further improvements in safety and performance have been made.

Brake fluids are being improved in performance, such as by increasing the boiling point and wet boiling point by incorporating boric acid ester of polyalkylene glycol monoalkyl ether into the main component, polyalkylene glycols.

(Plot B to be solved by the invention) Regarding brake systems, the installation rate of anti-lock brake systems is increasing due to the strong demand for improved braking performance in recent years.

In an anti-lock brake system, the brake fluid flow path is very narrow, so if sediment is present in the fluid, the flow path may become clogged, and the fluid pressure may not be transmitted properly. Therefore, in order to further improve the reliability of the anti-lock brake system, it is necessary to further reduce the amount of precipitate that forms in the liquid as it is used.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have made extensive efforts to elucidate the factors that cause precipitation in brake fluid and to take measures to prevent it.

A metal corrosion test specified in JIS K 2233 was conducted, and the precipitates formed in the brake fluid were analyzed, and the precipitates were found to be copper compounds. From this, it was assumed that the precipitate was caused by the combination of copper and a certain component of the brake fluid, so a compound was added to the brake fluid that had the effect of not forming a precipitate even when it combined with copper. The effectiveness was confirmed.

As a result, we found that the formation of precipitates can be suppressed by adding one or two nitrogen-containing compounds represented by general formulas (1) and (II) to a non-mineral oil-based automotive hydraulic brake fluid, The invention has been completed.

Conventional brake fluids contain antioxidants, metal deactivators, metal rust inhibitors, pH adjusters, lubricants, and the like to ensure long-term corrosion protection and oxidation stability. The present invention does not preclude their addition.

In other words, an automotive fluid that suppresses the formation of precipitates without impairing corrosion resistance by coexisting them with one or two of the nitrogen-containing compounds mentioned above, and that satisfies the standards and practical performance of automotive brake fluids. It becomes possible to provide a pressure brake hydraulic fluid composition.

Therefore, the non-mineral oil-based automotive hydraulic brake fluid composition of the present invention has the following formulas (I) and (U) (R1 and R
1 is a hydrogen atom or a phenol group, n is an integer of 0, 1.2 or 3, and m is an integer of 0°1.2.3 or 4.
The present invention is characterized in that 0.005% by weight or more, preferably 0.01 to 0.1% by weight, of seeds is added as a suspending agent. In the present invention, the above suspending agent may optionally contain 0.1% by weight or more, preferably 0.01 to 0.1% by weight.
It may be used in an amount exceeding % by weight, however, there is no advantage in using it in an amount greater than that in terms of cost and effectiveness.

In the case of the above formulas (1) and (IF), in the nitrogen-containing compound of formula (I), R and Rt are a hydrogen atom and a phenol group, respectively, and n-0, and in the case of formula (It), m −
Those exhibiting 3 are preferable.0 The constituent ratios of the above-mentioned additives constituting the composition of the present invention are arbitrary.

(Example) The present invention will be described below with reference to comparative examples and examples, but the present invention is not limited to these examples.

1-4 1-8 0.5% by weight of antioxidant (bisphenol) in the base liquid of automotive hydraulic brake hydraulic fluid containing boric acid ester of polyalkylene glycol monoalkyl ether;
metal deactivator (benzotriazole) 0.2% by weight,
Each liquid obtained by adding the additives shown in Table 1 to a solution containing 1.0% by weight of a pH adjuster (dicyclohexylamine) was evaluated for precipitates using the following test method. The results are shown in Table 1.

Harm (Test Method) The evaluation test for the precipitate was conducted with reference to the metal corrosion test of JIS K 2233, considering that the precipitate is a copper compound. That is, 50 cm of copper plate 2 and 100 m of brake fluid containing 10% water by weight were placed in an arbitrary glass container, held at 100±2°C for 672±2 hours, and then subjected to JIS K 2233 metal corrosion test 7.7.
・The amount of precipitation is evaluated by the operation in 5 (3).

From the evaluation results shown in Table 1, the following was confirmed.

The amount of precipitate produced in each of the test solutions of Examples 1 to 8 was 0.
It is sufficiently small at 1% by volume or less, especially 0.0% in Examples 1 to 3.
It shows better performance with less than 0.05% by volume. On the other hand, in Comparative Examples 1 and 2, the amount of precipitate was very large at 2.5% by volume or more, and in Comparative Example 3.4, it was smaller than Comparative Example 1.2, but larger than Examples 1 to 8. ing.

(Effects of the Invention) As is clear from the evaluation results in Table 1, the composition of the present invention has the following properties:
Compared to Comparative Examples 1 to 4, Examples 1 to 8 were more effective in suppressing the formation of precipitates.

Based on the above, by providing an automotive hydraulic brake hydraulic fluid composition that significantly reduces the amount of sediment, it is possible to contribute to further improvements in the safety, performance, and reliability of automobiles. .

Claims (1)

[Claims] 1. Non-mineral oil-based automotive hydraulic brake fluid has the following general formulas (I) and (II) ▲mathematical formulas, chemical formulas, tables, etc.▼---(I) ▲mathematical formulas, Chemical formulas, tables, etc. are available▼---(II) (R_1 and R_2 in the above formula are hydrogen atoms or phenol groups, n is an integer of 0, 1, 2, or 3, m is 0, 1,
(representing an integer of 2, 3 or 4), one or two selected from nitrogen-containing compounds represented by
．． A hydraulic brake hydraulic fluid composition for an automobile, characterized in that it contains 0.005% by weight or more.