KR101458630B1 - Compositions for Brake Fluids Comprising Tartaric acid and Imidazole - Google Patents

Abstract

(B) a corrosion inhibitor; and (c) a brake fluid comprising a mixture of tartaric acid, imidazole, or tartaric acid and imidazole as an antioxidant, the composition comprising (a) a glycol compound and a boron- ≪ / RTI > The present invention provides a brake fluid composition improved in thermal oxidation prevention, metal corrosion prevention and high temperature corrosion prevention performance. The brake fluid composition of the present invention has excellent thermal oxidation resistance and prevents corrosion of the metal point of the test piece and precipitation of boronic acid, thereby remarkably improving the durability for a long period of time. The influence of the equilibrium reflux boiling point and the wet equilibrium reflux boiling point is extremely small Oxidation and corrosion protection against high temperature is very good.

Description

Compositions for Brake Fluids Comprising Tartaric Acid and Imidazole < RTI ID = 0.0 >

The present invention relates to a composition for a brake fluid.

TECHNICAL FIELD The present invention relates to a brake fluid composition for automobiles used in an automotive system brake device, and is a brake fluid composition comprising a solvent, a metal corrosion inhibitor and an antioxidant. More specifically, the present invention relates to a process for producing a corrosion inhibitor, which comprises a mixture of a glycol compound and a boron-containing compound as a solvent, a corrosion inhibitor, a mixture of tartaric acid, imidazole or tartaric acid and imidazole as an antioxidant, To an automotive brake fluid composition.

The brake fluid plays an important role in accurately transferring the pressure generated by the master cylinder to the wheel cylinder. If there is a problem in this process, the result is a deterioration of the brake responsiveness. There are several requirements related to its chemical and physical properties of such brake fluid. The first is the high equilibrium reflux boiling point (ERBP). Braking liquids can cause boiling in certain situations, since liquids that are difficult to boil by themselves or high temperatures when braking. If boiling occurs, the pressure of the master cylinder can not be accurately transmitted and a stable braking force can not be expected. The temperature of the frictional heat generated by frequent disc brakes in the brake system is about 800 ° C. Such high-temperature brake fluid can be oxidized by heat and deterioration of corrosion prevention performance may cause safety accidents. The second is the high wet equilibrium reflux boiling point. The brake fluid is a hygroscopic liquid and requires low hygroscopicity. However, it is important not to lower the boiling point when absorbing moisture to some extent. If the boiling point is lowered by absorbing moisture in the atmosphere, a vapor lock may occur and cause a safety accident. And the viscosity change rate should be small even within a wide temperature range. Further, the brake fluid is added with a metal corrosion inhibitor and an oxidation stabilizer which prevent corrosion of various metals present in the brake device and make them durable.

In the case of a commonly used brake fluid, a type in which only a glycol ether compound is used as a solvent or in which about 30 to 50 wt% of a boron ester compound is added to a solvent is mainly used. The brake fluid of the type using only the glycol ether compound absorbs moisture in the air during a long period of use and lowers the wet boiling point to cause a vapor lock to cause a braking incapable accident, There is a weak point in ability. Further, the use of a boron ester compound in the form of a brake fluid containing about 30 to 50% by weight of a boron ester compound increases the boiling point of equilibrium reflux and the boiling point of wetting, resulting in a higher degree of safety than that of the glycol ether compound alone. However, it has the disadvantage of corrosion of metal parts due to precipitation of boronic acid due to hydrolysis of boron ester compound during moisture absorption. The protection of metals and non-ferrous metals from corrosion by such brake fluid can be achieved by corrosion inhibiting additives and antioxidants.

As a result of intensive research to solve the problems of the prior art described above, the present inventors have found that when a conventional brake fluid composition contains a mixture of tartaric acid, imidazole, or tartaric acid and imidazole, To thereby provide a composition for an automotive brake fluid capable of improving thermal oxidation prevention performance, chlorine ion corrosion prevention performance, high temperature corrosion prevention performance and boron acid precipitation prevention performance.

Accordingly, it is an object of the present invention to provide a brake fluid composition.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention and claims.

According to an aspect of the present invention, there is provided a brake fluid composition comprising a glycol compound and a boron-containing compound as a solvent, a metal corrosion inhibitor as a solvent, and a mixture of tartaric acid, imidazole or tartaric acid and imidazole as an antioxidant .

The inventors of the present invention have made intensive studies to solve the problems of the prior art described above. As a result, the present invention has found that when a mixture of tartaric acid, imidazole or tartaric acid and imidazole is included in the conventional composition, It is possible to improve the antioxidant performance, the chlorine ion corrosion inhibition performance, the high temperature corrosion prevention performance and the boronic acid precipitation prevention performance.

As used herein, the term " brake fluid " is a non-petroleum liquid for a hydraulic brake of an automobile used in an automobile (vehicle) system braking system and is used to accurately transmit pressure generated in a master cylinder to a wheel cylinder during operation It is a liquid substance.

In the composition of the present invention, the solvent includes any glycol compound known in the art. The glycol compound is preferably selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, methylene glycol, dimethylene glycol, trimethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, polyalkylene glycol, ≪ / RTI > More preferably, the glycol compound suitable for the composition of the present invention is ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyalkylene glycol or glycol ether.

In the composition of the present invention, the glycol ether may be any of those known in the art, but preferably ethylene glycol ethyl ether, diethylene glycol ethyl ether, triethylene glycol ethyl ether, ethylene glycol methyl ether, diethylene Ethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, triethylene glycol butyl ether, polyethylene glycol butyl ether, dipropylene glycol methyl ether, polypropylene glycol methyl ether and the like. ≪ / RTI > More preferably, the glycol ether suitable for the composition of the present invention is selected from the group consisting of ethylene glycol methyl ether, diethylene glycol methyl ether, triethylene glycol methyl ether, polyethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, triethylene glycol Butyl ether, polyethylene glycol butyl ether, and most preferably triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, or polyethylene glycol monobutyl ether.

In the composition of the present invention, the brake fluid of the present invention comprises a boron-containing compound. Preferably, the boron-containing compound is selected from the group consisting of boric acid, a boron compound, sodium borate and potassium borate, more preferably a boron compound, and still more preferably a boron ester compound. Most preferably tris [2- [2- (2-methoxyethoxy) ethoxy] ethyl] orthoborate.

According to a most preferred embodiment of the present invention, the solvent used in the present invention is a mixture of polyalkylene glycol, glycol ether and boric acid ester compound.

In the composition of the present invention, the content of the solvent is preferably 20-99% by weight, more preferably 40-99% by weight, more preferably 60-95% by weight, More preferably from 70 to 95% by weight, and most preferably from 85 to 95% by weight.

When polyalkylene glycols, glycol ethers and boric acid ester compounds are used as the solvent, the content of the polyalkylene glycol is preferably 1.0-80 wt%, more preferably 1.0-60 wt%, based on the total weight of the solvent, , Even more preferably from 5.0 to 50 wt%, even more preferably from 5.0 to 30 wt%. The content of the glycol ether is preferably 20-90% by weight, more preferably 50-90% by weight, and even more preferably 60-85% by weight, based on the total weight of the solvent. The content of the boric acid ester is preferably 0.1-70% by weight, more preferably 0.1-60% by weight, even more preferably 1.0-50% by weight, still more preferably 1.0-50% by weight, 30% by weight.

The metal corrosion inhibitor of the present invention includes various metal corrosion inhibitors known in the art. According to a preferred embodiment of the present invention, the corrosion inhibitor used in the present invention is triazole, an amine compound or a mixture thereof.

The triazoles usable in the present invention include various triazoles known in the art, and preferably the triazoles are selected from the group consisting of benzotriazole, tolythriazole, octylthiazole, decyltriazole, And mixtures thereof. More preferably, the triazole is a benzotriazole or a tolyltriazole.

In the composition of the present invention, the preferable content of the triazole as the metal corrosion inhibitor is 0.1-10% by weight based on the total weight of the composition, more preferably 0.5-5.0% by weight.

Amine compounds which can be used in the present invention include alkyldiethanolamines (e.g., methyldiethanolamine), monoethanolamine, diethanolamine, triethanolamine, cyclohexylamine, morpholine, phenylmorpholine, ethanolamine, di- -Ethylhexylamine, di-N-butylamine, monoamylamine, diamylamine, dioctylamine, salicylmonoethanolamine and di-beta-naphthyl-p-phenylenediamine. Most preferably, the amine compound usable in the present invention is cyclohexylamine or alkyldiethanolamine.

In the composition of the present invention, the preferred content of the amine compound as the metal corrosion inhibitor is 0.1-10 wt%, more preferably 0.5-10 wt%, based on the total weight of the composition.

The brake fluid composition of the present invention essentially contains a mixture of tartaric acid, imidazole or tartaric acid and imidazole as an antioxidant. As demonstrated in the following examples, a mixture of tartaric acid, imidazole or tartaric acid and imidazole exhibits very good performance in terms of thermal oxidation and durability to heat.

Imidazoles that can be used in the present invention include various imidazoles known in the art, and preferably the imidazole is selected from the group consisting of 1H-imidazole, 1-methylimidazole, 1- ethylimidazole, 1- ( 1-methylimidazole, 1-phenylimidazole, benzimidazole, N-vinylimidazole and 2-mercapto-1-methylimidazole from the group consisting of Is one or more imidazole compounds selected. Most preferably, the imidazole is 1H-imidazole.

In the composition of the present invention, the preferable content of the mixture of tartaric acid and imidazole as the antioxidant is 0.1-10% by weight based on the total weight of the composition, more preferably 0.5-5.0% by weight. The preferred weight ratio of the two components tartaric acid to imidazole in the mixture of tartaric acid and imidazole as the antioxidant is 0.1: 1 to 1: 0.1.

In the brake fluid composition of the present invention comprising a mixture of a glycol compound and a boric acid ester compound, a corrosion inhibitor and a mixture of tartaric acid, imidazole or tartaric acid and imidazole as an antioxidant, From 85 to 99% by weight of the mixture, from 0.5 to 10% by weight of a corrosion inhibitor and from 0.5 to 5.0% by weight of a mixture of tartaric acid, imidazole or tartaric acid, imidazole as an antioxidant.

The brake fluid composition of the present invention is excellent in the prevention of long-term corrosion of metals and the prevention of thermal oxidation by heat. Therefore, the brake fluid composition of the present invention improves the anti-oxidation and endurance corrosion by adding an antioxidant having a different structure from that of the prior art, and solves the problem that the brake fluid boils at a high temperature. It also prevents corrosion of surrounding metal parts due to chlorine ion corrosion or boronic acid precipitation.

The features and advantages of the present invention are summarized as follows:

(a) The brake fluid composition of the present invention is characterized by using a mixture of tartaric acid, imidazole or tartaric acid and imidazole as a differentiated antioxidant, and a corrosion inhibitor.

(b) The present invention provides a brake fluid composition improved in thermal oxidation prevention, metal corrosion prevention and high temperature corrosion prevention performance.

(c) The brake fluid composition of the present invention is excellent in thermal oxidation resistance, and has a long-term durability improved by preventing corrosion of the metal point of the test piece and precipitation of boronic acid, and the influence on the equilibrium reflux boiling point and the wet equilibrium reflux boiling point Very low oxidation and corrosion resistance to high temperatures is very good.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention, and it is to be understood by those skilled in the art that the present invention is not limited thereto It will be obvious.

Example

Manufacturing example

The brake fluid composition of the present invention having the composition shown in the following Table 1 was prepared:

function Composition (% by weight) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 solvent Polyalkylene glycol 17 17 5 5 17 5 Polyethylene glycol monomethyl ether 23 23 15 14 23 14 Polyethylene glycol monobutyl ether 24 24 21 13 24 13 Treethylene glycol monomethyl ether 33.6 33.6 24 13 33.6 13 Boric acid ester compound - - 32.6 52.6 - 52.6 Metal corrosion
Inhibitor Benzotriazole 0.6 0.6 - - 0.6 - Tolythriazole - - 0.6 0.6 - 0.6 Alkyldiethanolamine 1.0 - 1.0 - - - Cyclohexylamine - 1.0 - 1.0 - Triethanolamine - - - 1.0 1.0 Antioxidant Tartaric acid 0.8 - 0.4 0.4 - - Imidazole - 0.8 0.4 0.4 - - Dibutylhydroxytoluene - - - - 0.8 0.8

The brake fluid compositions of Examples and Comparative Examples were prepared according to the compositions of Table 1, respectively. The boric acid ester compound is tris [2- [2- (2-methoxyethoxy) ethoxy] ethyl] orthoborate, and imidazole is 1H-imidazole. At this time, each component was stirred and mixed at room temperature (25 ° C) for 1 hour, and filtration was performed by microfiltration (5 μm).

Experimental Example

A thermal oxidation test, a chlorine ion metal corrosion test, a high temperature metal corrosion test, an antioxidation test, an equilibrium reflux boiling point, a wet equilibrium reflux boiling point, and a boronic acid precipitation test were conducted on the compositions of the brake fluid samples and the comparative examples (Table 1) And the results are shown in the following Table 2-7.

 Thermal oxidation test (132 占 폚 占 18 hr 占 copper powder 2 g 占 bubble 120 ml / min) division Example 1 Example 2 Example 3
Example 4 Comparative Example 1 Comparative Example 2 Item standard Thermal oxidation
exam(%) Preliminary alkalinity
Rate of change Max. 20%
14%
16%
15%
16%
70%
85%
pH change report 0.5 0.6 0.5 0.5 2.2 2.5

The following tests were conducted to evaluate the superiority of brake fluid for heat and oxidation. In order to accelerate the oxidation of the heat, copper powder and air bubbles are injected. Put 50 ml of brake fluid and 2 g of copper powder in a 250 ml Erlenmeyer flask and prepare by using air tube, cooler and thermometer. Bubbles are injected through the air tube at a rate of 120 ml / min and the brake fluid is stirred at 132 ° C for 18 hours and cooled. After that, the reserve acidity of the brake fluid is measured, and the amount of change is checked by comparing the preliminary alkalinity before and after the test.

As a result of the measurement, as shown in Table 2, it was confirmed that the rate of change in the preliminary alkalinity of the brake fluid using a mixture of tartaric acid, imidazole, or tartaric acid and imidazole as a result of the thermal oxidation test was comparative (that is, (Brake fluid not containing a mixture of tric acid and imidazole). The pH change rate of the brake fluid using a mixture of tartaric acid, imidazole or tartaric acid and imidazole was also 4-5 times better than the comparative example. It was confirmed that a mixture of tartaric acid, imidazole or tartaric acid and imidazole was effective in preventing oxidation of the brake fluid by heat.

Metal corrosion test (100 ℃ × 120 hr × 5% water, 25 ppm of NaCl added) division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Item standard    Chloride ion corrosion test (mg / ㎠) Annotation ± 0.2 0.02 0.02 0.01 0.01 0.06 0.12 River ± 0.2 0.02 0.02 0.04 0.03 0.08 0.14 aluminum ± 0.1 0.02 0.01 0.01 0.01 0.25 0.37 cast iron ± 0.2 0.02 0.02 0.02 0.05 0.11 0.12 Brass ± 0.4 0.05 0.06 0.05 0.02 0.49 0.63 copper ± 0.4 0.04 0.08 0.04 0.03 0.55 0.65 zinc ± 0.4 0.06 0.06 0.05 0.07 0.35 0.42 Exterior No corrosion Good Good Good Good Aluminum part Aluminum part

The following tests were conducted to evaluate the superiority of brake fluid on chloride ion. Corrosion test for chlorine ion was carried out according to KS M 2141 standard and metal corrosion test was conducted by adding 25 ppm of chlorine ion to accelerate corrosion of brake fluid. Each brake fluid was put into a non-mineral oil brake fluid test container for automobiles, the temperature was adjusted to 100 ° C, and then the standard test piece was immersed for 120 hours.

As a result of the above measurement, as shown in Table 3, the corrosion resistance of the brake fluid using a mixture of tartaric acid, imidazole or tartaric acid and imidazole was 10 times or more superior to that of the comparative example. In addition, in the evaluation of appearance corrosion resistance (ie, brake fluid not containing tartaric acid, imidazole, or a mixture of tartaric acid and imidazole), dot corrosion occurred in the aluminum metal upon exposure to chlorine ions. This confirms that the mixture of tartaric acid, imidazole or tartaric acid and imidazole improved the metal corrosion resistance of the brake fluid to chloride ions.

High temperature metal corrosion resistance test (120 캜 120 hr) division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Item standard   High temperature metal corrosion test (mg / ㎠) Annotation ± 0.2 0.01 0.02 0.01 0.02 0.08 0.09 River ± 0.2 0.02 0.02 0.02 0.03 0.11 0.11 aluminum ± 0.1 0.01 0.01 0.03 0.02 0.20 0.20 cast iron ± 0.2 0.02 0.01 0.02 0.03 0.11 0.13 Brass ± 0.4 0.03 0.02 0.03 0.03 0.20 0.22 copper ± 0.4 0.03 0.04 0.05 0.05 0.18 0.20 zinc ± 0.4 0.04 0.04 0.05 0.06 0.35 0.41

The following tests were conducted to evaluate the superiority of brake fluid for high temperature durability. The high temperature corrosion test was carried out according to KS M 2141, and the results were observed after 120 hours at 120 ° C.

As a result of the above measurement, as shown in Table 4, the evaluation results of the high-temperature endurance corrosion test showed that the brake fluid containing a mixture of tartaric acid, imidazole or tartaric acid and imidazole had a weight change amount in the high temperature endurance corrosion evaluation, The brake fluid not containing a mixture of tartaric acid, imidazole, or a mixture of tartaric acid and imidazole) was about 5 times better. It was confirmed that a mixture of tartaric acid, imidazole or tartaric acid and imidazole improved the metal corrosion resistance of the brake fluid to high temperatures.

Antioxidant test (23 ° C × 70 hr + 70 ° C × 168 hr) division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Item standard    Antioxidant activity (mg / ㎠) aluminum ± 0.05 0.01 0.01 0.01 0.01 0.03 0.03 cast iron ± 0.3 0.02 0.02 0.02 0.01 0.19 0.21

The following tests were conducted to evaluate the superiority of brake fluid on antioxidant properties. The antioxidant activity test was carried out according to the procedure of KS M2141 5.9, proceeded at 23 ° C for 70 hours, and left at 70 ° C for 168 hours, and then the appearance and weight change of the metal specimen were measured. The above test is a test to evaluate corrosion resistance by adding benzoyl peroxide and rubber to the brake fluid. The outer surface of the aluminum metal and the cast iron metal piece in contact with the tin plate by the brake fluid is corrosive enough to be visually discernible .

As a result of the measurement, as shown in Table 5, the brake fluid containing a mixture of tartaric acid, imidazole or tartaric acid and imidazole in the examples was used as a comparative example (i.e., a mixture of tartaric acid, imidazole or tartaric acid and imidazole The antioxidant properties of benzoyl peroxide were superior to those of benzoyl peroxide more than twice as much as those of the brake fluid not containing the mixture. It was confirmed that the mixture of tartaric acid, imidazole or tartaric acid and imidazole improved the antioxidative activity of the brake fluid.

Equilibrium reflux boiling point and wet equilibrium reflux boiling point test according to composition division Example 1
Example 2
Example 3
Example 4
Example 5
Comparative Example 1
Item standard 3 species 4 species Equilibrium reflux
boiling point 205 ℃ or higher 230 ℃ or higher 251 251 261 271 251 271 Wet equilibrium reflux
boiling point 140 ℃ or more 155 ℃ or higher 149 150 160 172 149 172

The following tests were conducted to evaluate the superiority of the brake fluid over the equilibrium reflux boiling point and the wet equilibrium reflux boiling point. The equilibrium reflux boiling point and the wet equilibrium reflux boiling point test were carried out according to the procedure of KS M2141 5.1.1, 5.1.4. As a result of the above measurement results, equilibrium reflux boiling point and wet equilibrium reflux boiling point test results showed equal results. It is considered that the equilibrium reflux boiling point and the wet equilibrium reflux boiling point are not largely affected by the addition of the composition of the present invention.

Boron acid precipitation test depending on the composition content division Example 1
Example 2
Example 3
Example 4
Comparative Example 1 Comparative Example 2 Item standard Boronic acid
Precipitation test Foreign matter and precipitation
Not to be none none none none Boronic acid
Precipitation Boronic acid
Precipitation

In order to evaluate the superiority of brake fluid on boronic acid, the following boronic acid precipitation test was carried out. The brake fluid was injected into the flask and after 72 hours at room temperature (25 ° C), precipitation of boronic acid was observed by hand or by naked eyes. As a result of the above measurement, as shown in Table 7, boronic acid precipitation test of the boron ester compound showed that boronic acid was not precipitated even after 72 hours in the brake fluid using alkyldiethanolamine or cyclohexylamine. However, in the case of the comparative example (i.e., the brake fluid not containing alkyldiethanolamine or cyclohexylamine), boronic acid precipitated after 72 hours. It was confirmed that the alkyldiethanolamine or cyclohexylamine improved the boronic acid precipitation preventing performance of the brake fluid.

Claims (1)

A brake fluid composition comprising (a) a mixture of a glycol compound and a boron-containing compound as a solvent, (b) a corrosion inhibitor, and (c) an antioxidant,
The composition comprises 85-99% by weight of a mixture of a glycol compound and a boron-containing compound as a solvent, 0.5-10.0% by weight of a corrosion inhibitor and 0.5-5.0% by weight of a mixture of tartaric acid and imidazole as an antioxidant,
The glycol compound as the solvent of (a) comprises 5.0-30% by weight of polyalkylene glycol and 60-85% by weight of glycol ether based on the total weight of the solvent, and the glycol ether is triethylene glycol monomethyl ether, polyethylene Glycol monomethyl ether, and polyethylene glycol monobutyl ether,
The boron-containing compound as the solvent of (a) is contained in an amount of 1.0-30% by weight, based on the total weight of the solvent, tris [2- [2- (methoxyethoxy) ethoxy] ethyl]
The brake fluid composition according to claim 1, wherein the corrosion inhibitor (b) is a tolylthiazole, an amine compound, or a mixture thereof, and the amine compound is an alkyldiethanolamine or cyclohexylamine.