GB2025455A

GB2025455A - Brake fluid

Info

Publication number: GB2025455A
Application number: GB7829434A
Authority: GB
Original assignee: Toho Chemical Industry Co Ltd
Current assignee: Toho Chemical Industry Co Ltd
Priority date: 1978-07-11
Filing date: 1978-07-11
Publication date: 1980-01-23
Also published as: GB2025455B

Abstract

Brake fluids of good quality which increase wet equilibrium reflux boiling point without increasing rubber swelling property and disperse or dissolve homogeneously the additives and metals extracted from rubber brake cups and cylinder pipes can be obtained by dissolving semipolar borates containing a bond represented by the formula, <IMAGE> which can be a hybridized orbital between SP<2> and SP<3> with regard to boron atom and having at least two hydroxyl groups outside said bond e.g. bis-glyceryl borate and heteroborates comprising an SP<2> hybridized orbital and containing butyl group and methyl group in their molecule in polyalkylene glycol monoalkyl ethers comprising a C1-C4 alkyl group.

Description

SPECIFICATION Brake fluid compositions for automobiles The present invention relates to brake fluid compositions for automobiles. More particularly, the invention pertains to brake fluid compositions for automobiles comprising borates having a semipolar structure, heteroborates containing butyl group and methyl group in their molecule and polyalkylene glycol monoalkyl ethers.

At present, an attempt has been made to obtain better brake fluids for automobiles having an increased wet equilibrium reflux boiling point by adding triborates comprising an SP2 hybridized orbital to polyalkylene glycol monoalkyl ethers which are used as brake fluids for automobiles.

(For example, United States Patent specification No. 3,625,899). However, brake fluids comprising such combinations have still a defect in that they are inferior to brake fluids comprising only a polyalkylene glycol monoalkyl ether in rubber swelling property. In a rubber swelling property test, therefore, the zinc oxide and fatty acids extracted from the rubber cup form an undesirable suspension state. Also, in a metal corrosion test, the ingredients extracted from the rubber cup react further with metals to form an insoluble precipitate. There is the possibility that the formation of such a precipitate results in the clogging of a fluid pressure feed pipe line for a brake fluid on actual travel of automobiles.

Therefore, an object of the present invention is to obviate the defects of prior art brake fluid compositions for automobiles.

Another object of the invention is to provide brake fluid compositions for automobiles of good quality.

Another object of the invention is to provide brake fluid compositions for automobiles which can satisfy the second class, No. 2 standard of JIS K-2233 and DOT-4 grade of Federal Motor Vehicles Safety Standard (FMVSS No. 116).

The other objects and advantages of the invention will be apparent from the following description of the invention.

As a result of various studies, the present inventors have now reached an invention of obtaining brake fluids of good quality which increase wet equilibrium reflux boiling point (hereinafter referred to as "WET-ERBP") without increasing rubber swelling property and disperse or dissolve homogeneously the additives and metals extracted from rubber cups and cylinder pipes by dissolving semipolar borates containing a bond represented by the formula,

which can be a hybridized orbital between SP2 and SP3 with regard to boron atom and having at least two hydroxyl groups outside said bond and showing rubber compression properties (hereinafter referred to as "the appointed semipolar borates") and heteroborates comprising an SP2 hybridized orbital and containing butyl group and methyl group in their molecule and showing a strong dissolving power (hereinafter referred to as "the appointed heteroborates") in polyalkylene glycol monoalkyl ethers comprising a C,-C4 alkyl group (hereinafter referred to as "the appointed polyalkylene glycol monoalkyl ethers").

With regard to the brake fluid compositions according to the present invention, there can be considered a mechanism that the ingredients extracted from a rubber cup and cylinder pipes are chelated with the appointed semipolar borates, and then dissolved in the appointed heteroborates, and finally homogeneously dispersed in the appointed polyalkylene glycol monoalkyl ethers, and thereby the precipitation of the ingredients can be prevented.

Thus, according to the present invention, there is provided brake fluid compositions for automobiles comprising as an effective ingredient a mixture of at least one of the appointed semipolar borates represented by the general formula,

wherein X, X', Y and Y' each are hydrogen atom, a group of the formula,

wherein a is 0, 1, 2 or 3, or a group of the formula,

wherein b is 1 or 2 provided that at least two hydroxyl groups are present in X + X' + Y + Y', at least one of the appointed heteroborates represented by the general formula, [{C4H2O-(CH2CH2-O-)k-}p, {CH3O-(CH2CH2O-)j-}p]B (II) wherein pis a positive number of 1 to 3/2, qis a positive number of 3/2 to 2 and p+ q is 3, kisa positive number of 1 to 3, and j is a positive number of 3 to 5, and at least one of the appointed polyalkylene glycol monoalkyl ethers represented by the general formula,

wherein R is a C,-C4 alkyl, lis O or a positive number of 3/2 or less, n is O or a positive number of 3/2 or less, and m is a positive number of 3 to 5 provided that there are the following relationship between I, m and n: 31+ m+ n) < 5 and

Here, the appointed semipolar borates can be obtained by the following three processes: Process (i) Two moles of at least one of polyhydric alcohols comprising vicinal hydroxyl groups (hereinafter referred to as "the appointed polyhydric alcohols") and one mole of boric acid are subjected to triesterification reaction.

Process (ii) Two moles of at least one of the appointed polyhydric alcohols and one mole of at least one of lower alkyl triborates having 1 to 3 carbon atoms are subjected to triesterification reaction by trnnsesterification.

Process (iii) Four mols of at least one of the appointed polyhydric alcohols and one mole of boric anhydride are subjected to triesterification reaction.

The appointed semipolar borates are exemplified by bisglyceryl borate, bisxylityl borate, bissorbityl borate, bismannityl borate, bis(glyceryloxyglyceryl) borate, bis (di(glyceryloxy)glyceryl) borate, (glyceryl, xylityl) borate, (glyceryl, sorbityl) borate, (glyceryl, mannityl) borate, (glyceryl, glyceryloxyglyceryl), borate, (glyceryl, di(g lyceryloxy)glyceryl) borate, (xylityl, sorbityl) borate, (xylityl, mannityl) borate, (xylityl, glyceryloxyog lyceryl) borate, (xylityl, d i(glyceryloxy)-glyceryl) borate, (sorbityl, mannityl) borate, (sorbityl, glyceryloxyglyceryl) borate, (sorbityl, di(glyceryloxy)glyceryl) borate, (mannityl, glyceryloxyglyceryl) borate, (mannityl, di(g Iyceryloxy)glyceryl) borate, (glyceryloxyglyceryl, d i(glyceryloxy)glyceryl) borate, (ethylene, xylityl) borate, (ethylene, sorbityl) borate, (ethylene, mannityl) borate, (ethylene, glyceryloxyglyceryl) borate, (ethylene, di(glyceryloxy)glyceryl) borate, etc.

Further, as the appointed polyhydric alcohols which are the starting material for producing these semipolar borates, there are enumerated ethylene glycol, glycerol, diglycerol, triglycerol, xylitol, sorbitol, mannitol, etc.

The above-mentioned reaction between at least one of the appointed polyhydric alcohols and boric acid can be easily carried out by heating the reaction mixture at a temperature of 50 to 300 C, and preferably 1 50 to 200 C, under reduced pressure or atmospheric pressure while the water formed is removed out of the reaction system.

The above-mentioned reaction between at least one of the appointed polyhydric alcohols and a lower alkyl triborate can be easily carried out by heating the reaction mixture at a temperature of 30 to 270 C, and preferably 100 to 200 C, under reduced pressure or atmospheric pressure while the alcohol formed is removed out of the reaction system. The lower alkyl triborates used in this case are exemplified by trimethyl borate, triethyl borate, tripropyl borate and triisopropyl borate.

The above-mentioned reaction between at least one of the appointed polyhydric alcohols and boric anhydride can be easily carried out by reacting the starting materials with each other partly at a temperature of 20 to 1 50 C, and preferably 50 to 90 C and then heating the reaction mixture at a temperature of 50 to 300 C, and preferably 150 to 250 C, under reduced pressure or atmospheric pressure while the water formed is removed out of the reaction system.

In any one of the said processes, the introduction of an inert gas such as nitrogen gas, carbon dioxide gas, etc., and the use of a solvent such as toluene, xylene, etc. accelerate the reaction.

Here, if bisethylene borate or (ethylene, glyceryl) borate which are beyond the scope of the appointed semipolar borates and which have at most only one hydroxyl group except in their semipolar structure portion is used, the ability of dispersing rubber additives and metals in a brake fluid becomes very weak. Therefore, ethylene glycol must be used in esterification of boric acid in admixture with a polyhydric alcohol having at least four hydroxyl groups.

Also, as the polyhydric alcohols comprising vicinal hydroxyl groups, there can be enumerated 1 ,2-propylene glycol, 1,2-butylene glycol, etc. in addition to said ethylene glycol. However, these polyhydric alcohols containing an alkyl side chain are not preferable since semipolar borates derived therefrom are remarkably weak in ability of suppressing rubber swelling.

The appointed heteroborates can be prepared by reacting boric acid, a lower alkyl triborate or boric anhydride with a system containing glycol ethers derived from starting alcohols containing butyl group such as ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, etc. and glycol ethers derived from starting alcohols containing methyl group such as triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, pentaethylene glycol monomethyl ether, etc. according to a usual process for preparing SP2 type triborates.The heteroborates are exemplified by (mono(monobutoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyl), poly(1.5 moles) (monomethoxydiethyleneoxyethyl)) borate, (mono(monobutoxyethyl), di(monomethoxytriethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyl), poly(1.5 moles) (monomethoxytriethyleneoxyethyl)) borate, (mono(monobutoxyethyl), di(monomethoxytetraethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyl), poly(1.5 moles) (monomethoxytetraethyleneoxyethyl)) borate, (mono(monobutoxyethyleneoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyleneoxyethyl), poly(1.5 moles) (monomethoxydiethyleneoxyethyl)) borate, (mono(monobutoxyethyleneoxyethyl), di(monomethoxytriethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyleneoxyethyl), poly(1.5 moles) (monomethoxytriethyleneoxyethyl)) borate, (mono(monobutoxyethyleneoxyethyl, di(monomethoxytetraethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxyethyleneoxyethyl), poly(1.5 moles) (monomethoxytetraethyleneoxyethyl)) borate, (mono(monobutoxydiethyleneoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxydiethyleneoxyethyl), poly(1.5 moles) (monomethoxydiethyleneoxyethyl)) borate, (mono(monobutoxydiethyleneoxyethyl), di(monomethoxytriethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxydiethyleneoxyethyl), poly(1.5 moles) (monomethoxytriethyleneoxyethyl)) borate, (mono(monobutoxydiethyleneoxyethyl), di(monomethoxytetraethyleneoxyethyl)) borate, (poly(1 .5 moles) (monobutoxydiethyleneoxyethyl), poly(1.5 moles) (monomethoxytetraethyleneoxyethyl)) borate, etc.

If heteroborates containing no butyl group which are beyond the scope of the appointed heteroborates are used, the dissolving power of the ingredients chelated with the appointed semipolar borates is remarkably reduced. Also, if alkyl groups other than methyl group exist together with butyl group in the molecule of the heteroborates, rubber swelling property becomes excessively high and is ill-balanced with the rubber compression properties of the appointed semipolar borates. Therefore, the presence of such alkyl groups is not preferable.

Also, it is unsuitable that the amount of the residue of a starting alcohol containing butyl group is larger than the amount of the residue of a starting alcohol containing methyl group, since the dissolving power of the ingredients chelated with the appointed semipolar borates thereby becomes weaker and rubber swelling property is increased.

On the other hand, if the length of an oxyethylene chain in the respective starting alcohols is shorter than that of an oxyethylene chain in the appointed heteroborates, equilibrium reflux point (hereinafter referred to as "ERBP") is reduced. Contrarily, if the former is longer than the latter, the kinetic viscosities of the brake fluids prepared therefrom are remarkably increased.

Also, it is not preferable to replace the oxyethylene chain of the appointed heteroborates by another oxyalkylene chain, since it decreases WET-ERBP.

On the one hand, the appointed polyalkylene glycol monoalkyl ethers include not only ethylene oxide adducts such as triethylene glycol monomethyl ether but also ethylene oxidepropylene oxide co-adducts such as monomethoxypropylene glycol tetraethylene glycol ether as represented by the general formula (III). Thus, specific examples of the appointed polyalkylene glycol monoalkyl ethers include triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, pentaethyleneglycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, pentaethylene glycol monoethyl ether, triethylene glycol monopropyl ether, tetraethylene glycol monopropyl ether, pentaethylene glycol monopropyl ether, triethylene glycol monoisopropyl ether, tetraethylene glycol monoisopropyl ether, pentaethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, pentaethylene glycol monobutyl ether, monomethoxytriethylene glycol propylene glycol ether, monomethoxytetraethylene glycol propylene glycol ether, monoethoxytriethylene glycol propylene glycol ether, monoethoxytetraethylene glycol propylene glycol ether, monopropoxytriethylene glycol propylene glycol ether, monopropoxytetraethylene glycol propylene glycol ether, monoisopropoxytriethylene glycol propylene glycol ether, monoisopropoxytetraethylene glycol propylene glycol ether, monobutoxytriethylene glycol propylene glycol ether, monobutoxytetraethylene glycol propylene glycol ehter, monomethoxypropylene glycol triethylene glycol ether, monomethoxypropylene glycol tetraethylene glycol ether, monoethoxypropylene glycol triethylene glycol ether, monoethoxypropylene glycol tetraethylene glycol ether, monopropoxypropylene glycol triethylene glycol ether, monopropoxypropylene glycol tetraethylene glycol ether, monoisopropoxypropylene glycol triethylene glycol ether, monoisopropoxypropylene glycol tetraethylene glycol ether, monobutoxypropylene glycol triethylene glycol ether, monobutoxypropylene glycol tetraethylene glycol ether, monomethoxypoly (3.5 moles) ethylene glycol poly(1.5 moles)propylene glycol ether, monoethoxypoly(3.5 moles) ethylene glycol poly(1.5 moles)propylene glycol ether, monopropoxypoly(3.5 moles)ethylene glycol poly(1.5 moles)propylene glycol ether, monoisopropoxypoly(3.5 moles)ethylene glycol poly(1.5 moles)propylene glycol ether, monobutoxypoly(3.5 moles)ethylene glycol poly(1.5 moles)propylene glycol ether, monomethoxypoly(1.5 moles)propylene glycol poly(3.5 moles)ethylene glycol ether, monoethoxypoly(1 .5 moles)propylene glycol poly(3.5 moles)ethylene glycol ether, monopropoxy poly(1.5 moles)propylene glycol poly(3.5 moles)ethylene glycol ether, monoisopropoxypoly(1 .5 moles)propylene glycol poly(3.5 moles)ethylene glycol ether, monobutoxypoly(1 .5 moles)propylene glycol poly(3.5 moles)ethylene glycol ether, etc.

These ethers can be obtained by reacting 3 to 5 moles of ethylene oxide or a mixture of ethylene oxide and propylene oxide (In this case, the amount of ethylene oxide added is 3 moles or more and the amount of propylene oxide added is 1.5 moles or less.) with 1 mole of methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol or butyl alcohol in the presence or absence of an acid or alkali catalyst at 50 to 30arc and at 1 to 15 kg/cm2, and preferably at 100 to 1 50 C and at 1 to 5 kg/cm2, or by adding 3 moles or more but less than 5 moles of ethylene oxide and then 1.5 moles or less of propylene oxide to 1 mole of the above-mentioned alcohol, or by adding 1.5 moles or less of propylene oxide and then 3 moles or more but less than 5 moles of ethylene oxide to 1 mole of the above-mentioned alcohol.

Here, in a relationship between polyoxyethylene group and polyoxypropylene group in the appointed polyalkylene glycol monoalkyl ether, if the average degree of polymerization of the polyoxyethylene group is lower than 3 as an absolute amount and if the molar fraction of the polyoxypropylene group in polyoxyalkylene group is larger than 1/3, it is impossible to improve the WET-ERBP of a braise fluid obtained by mixing the ether with the appointed semipolar borate and the appointed heteroborate. It is not preferable from the viewpoint of properties.

Also, a pH adjusting agent, a metal corrosion inhibitor and an antioxidant, etc. may be added to the brake fluid composition according to the present invention if necessary. These additives are not limited to specific ones.

As described above, the brake fluid compositions for automobiles according to the present invention can satisfy the second class, No. 2 standard of JIS K-2233 and DOT-4 grade of Federal Motor Vehicles Safety Standard (FMVSS No. 116). Further, they increase WER-ERBP without increasing rubber swelling property and disperse or dissolve homogeneously the additives and metals extracted from rubber cups and cylinder pipes to prevent precipitation thereof. Thus, in rubber swelling property test and metal corrosion test, the brake fluid compositions for automobiles according to the present invention do substantially not show the formation of precipitate in contrast with the brake fluid compositions prepared according to the technique as described in United States Patent specification No. 3,625,899.

The following examples will serve to illustrate the practice of the invention in more detail.

Example 1 Into a four-neck flask with a stirrer, a thermometer, a gas inlet and a water measuring tube connected with a reflux condenser were charged 184.2 g (2 moles) of glycerol and 61.8 g (1 mole) of boric acid. The charged materials were reacted at 190 to 200 C for 4 hours under nitrogen gas flowing condition. Thus, 54 g of water was distilled off and colorless and transparent bisglyceryl borate was obtained.

Also, into another reactor were charged 11 8 g (1 mole) of ethylene glycol monobutyl ether, 328 g (2 moles) of triethylene glycol monomethyl ether and 61.8 9 (1 mole) of boric acid. The charged materials were reacted at 160 to 170 C for 3 hours under nitrogen gas flowing condition. Thus, 59 g of water was distilled off and light yellow and transparent {mono(monobutoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate was obtained.

These borates were mixed with triethylene glycol monomethyl ether in the following weight ratio to form a brake fluid composition.

% by weight CH 0 OH C 10 CHO , OHC 1 6 +H I CH2 H CH2 H C4HgOCH2CH20 CHo-(CH2CH2o-)3 B 9 CH3O- ( CH2CH2O-) CH30-(CH2CH2o-)3H 81 Example 2 Into the same reactor as that used in Example 1 were charged 332.4 g (2 moles) of diglycerol and 145.8 g (1 mole) of triethyl borate. The charged materials were reacted at 90 to 100 C for 6 hours. Thus, 138 g of ethyl alcohol was distilled off and light yellow and transparent bis(glyceryloxyglyceryl) borate was obtained.

Also, in another reactor, 61 8 g (3 moles) of triethylene glycol monobutyl ether was first reacted wth 69.6 g (1 mole) of boric anhydride at 80 to 90 C. Then, 756 g (3 moles) of pentaethylene glycol monomethyl ether was charged and the mixture was reacted at 190 to 200 C. Thus, 54 g of water was distilled off and colorless and transparent {poly(1.5 moles)(monobutoxydiethyleneoxyethyl), poly(1.5 moles)(monomethoxytetraethyleneoxyethyl)) borate was obtained.These borates were mixed with tetraethylene glycol monoethyl ether in the following weight ratio to form a brake fluid composition.

by by weight ClH2O(B) 5/OH2C I L (t) CHO , OHC CH2 CH2 I 1 O CI 1 CH 2 CH2 CHOH CHOH CH2 H CH20H [ {C4H9o-(CH2CH2o-)3-}l 5-{CH3o-(CH2CH2o )5 }1-5 29 C 2H5C-(CH2CH2C-)H 70

Example 3 In the same manner as in Example 1, 92.1 g (1 mole) of glycerol, 2609 (corresponding to 1 mole) of a 70% aqueous sorbitol and 61.8 g (1 mole) of boric acid were reacted to obtain (glyceryl, sorbityl) borate which was light yellow and transparent liquid.

Also, 162 g (1 mole) of diethylene glycol monobutyl ether, 416 9 (2 moles) of tetraethylene glycol monomethyl ether and 188.1 9 (1 mole) of triisopropyl borate were reacted to obtain fniono(monobutoxyethyleneoxyethyl), di(monomethoxytriethyleneoxyethyl)} borate.

These borates were mixed with monomethoxytriethylene glycol propylene glycol ether in the following weight ratio to form a brake fluid composition.

by weight CH20X(~)/oH2 1 B CHO ~ OHC +H CHOH CH2 H HOCH CHOH CH20H C4H90-(CH2CH20 25 CH30-(CH2CH20-)4 CH30-(CH2CH23-)4 CH3 I CH30-(CH2CH20-)3-CHCH2-OH 74 Example 4 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C() OH2C CHO w CHO ,OHC 3 6 6 OHC l CH20H +H CH2 H C 4H9CCH2CH2 0 CH30;(CH2CH20-) / B 37 CH3C-(CH2CH2 C-) CH3O-(CH2CH2O-)4H 60 Example 5 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

I by weight CH20 o( - wOH2C I CHO OHC ) 6 +H' I | 6 +H' l CH2 H CH2 H C4H90-(CH2CH20-)2 CH3C-(CH2CH2C-)3 B 56 CH3C-(CH2CH2C-) 3 CH33-(CH2CH2 -)3H 3H Example 6 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C() HC CHO CHO O.i | 6 +H CH2 1 C CH2 I CHOH CHOH CH2 H CH23H C4H90-CH2CK20 MM CH3 C-(CH2CH2O-)3 B 149 CH30-(CH2CH20-)3 CH3C- (CH2CH2C-)3H 50

Example 7 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C&num;() OH C CHO ' .OH2C | 6 +H' 5 HOCH HOCH CH2 H C14H9C- (CH2cH2 -)3 CH3C-(CH2CH2C-)3 B 50 CH3C-(CH2CH2C-)3 CH C3H70-CHCH20-(CH2CH2-)qH 45 Example 8 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH20 o( wOH2C I BTh+) CHO ,OHC S 6 +H CHOH CH2 5 HOCH O HOCH CH, 2 CH20H CHOH CH20H E{C14H9C(CH2CH2O-)2-}1.5, fCH3O-(CH2CH20-)14-}1 53B 30 CH CH3 CHO CHCH2O-(CH2CH2C-)3H 65 CH3

Example 9 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight Cm20\( ~ OH2C HO B i (+) C OH 6 3 CH2 H lwH2 0 OH 0 CHOH OH OW EtCH9O-(CH2CH20-) 3} 5 fCH3O-(OH2CH2O-)3-}15JB 50 C2H50 (CH2CH20 )5 147 Example 10 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

by weight 3 ~CH2C -'-- +) CHO ,OHC I HOCH CHOH 2 HOCH CHOH CH2CH HOCH2 C14H9C-CH2CH2 C CH3C- (CH2CH2C-)14 1 / 148 CH30-(CH2CH20-)4 CH3C C3H70-(CH2CH20-)3H 50

Example 11 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C OH C B CHO / by z CHC I g +H' | d +Ho CHOH CHOH 6 HOCH CHOH CHOH HOCH2 CH2 H C4H90-(CH2CH20-)2 CH3C-(CH2CH2C-)3 B 144 3C-(CH2CH2O-)3 CH C2H5C- ( CH2CH2C-) 3H 5a Example 12 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH20 c B LI CHO OH2C 6+H' 1 'H2 CH2 I CH2 CHOH I CH2 H ({C14H9C-(cH2CH2C-)3-)15, (CH3C-(CH2cH2-)3-}15 ] B 9 CH CH30-CHCH20-(CH2CH20-)3H 90

Example 13 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH CH2C CHoM B - CHC S +H CH2 CH2 C 3 CH2 CH2 I I CHOH CHOH CH2 H CH2 H C14H90-CH2CH2O CH3C-(CH2CH2C-)3 B 52 CH3C- (CH2CH2C-)3 CH30-(CH2CH20')3 F (F"J cH3C-cCH2CH2C-)3.5-( \ CHCH20 i H 5 Example 14 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight 2 \ OH C CH - - OHC 1 1 CHOH CH2 H HOCH CHOH I CH20H ((C4H90-cH2CH2C-)15, {(CH3C-(CH2CH2C-)3-)153B 50 c2Hso(CCIHC3H2C)l.scCH2CH2C)3. 5H 49

Example 15 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH20N( ~ )/OH2CI CHO ,OHC I CHC 10 I d+H HOCH CH2 H HOCH CH20H ((C14H9C-CH2CH2C-)1 5' fCH3C-(CH2CH2C-)3-}1,5 ] B 50 cH30-(CH2CH20-)3H 140 Example 1 6 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH20 o( / H2C B CHO .OHC 3 I ; g +H-'c I CH2 H CH20H C4HgO-CH2CH20 \ CH30-(CH2CH20-)3 / B 27 CH3C-(CH2CH2 3 C14H90-(CH2CH2O-)5H 10 CH3O-(CH2CH2O-)14H 60

Example 17 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2O()OH2C (+) CHO < OHC 5 :HO CH20H CH20'.

4H90-(CH2CH20- -} , {CH30-(cH2cH2g-)4-},s5 ] B 25 CH3 \ OH3 OH / CH -(CH2CH2 - -CHCH20H CH3 20 C2H5O-(CH2C C) 3H 50 Example 18 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CHO C B / o\(+,1 CHO OHC | 5 +Ho ff l CHOH HOCY 3 HOCH CHOH CHOH HOCH CH2 H HOCH2 C4H9U-CH2CH2D CH30- ( CH2 CH2 O- ) 3 27 CH3C- (CR2CH2O-)3 /CH H20-1.5(CH2CH20-)35H CHC 30 CH30-(CH2CH20-)3H 40

Example 1 9 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH20 o( )/ H2 - -- CRC CHO 5 HOCH CH20H I HOCH CH2 H [ {C4H9o-(CH2CH2o-)3-}l 5, tCH3C-(CH2CR2C-)5-}15 ] B 15 C4HgO-(CH2CH20-)3H 15 C 2H5C-(CR2CH2O-)14H 6-5 Example 20 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

by weight CH20 21 21 CHO ' ,OH2C 1 6 6 Cur2 2 o CR2 CHOH; CH2OH C4H90-(CH2CH20-)2 CH30-(CH2CH20-)4 CH30-(CH2CH20-)4 CR3 C2HSO-(CH2CH20-)3-CHC20H 38 C2H5 (CH2cH2 )4H 50

Example 21 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight 0,(~,,0H2 C C1 < CHO OH2C HOCH HOCH I CH2 H C(C4Hg0-C2Ca0-)1.5 (0H30-(OH2OR2O-) 5 B 47 CR3O(CCIRRC3R2O)l.5(OH2OH2O ) 35R CH30,( I CH30-(CH2CH20-)3 5-\CHCH2 2 1.5 25 Example 22 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

ss by weight CH2 B / to( ) CHO ,OHC 3 S+R CH2 H -^H2WH C 14R9 CCR2CR2 0 CH30-(CH2CH20-)4 15 CH30-(CH2CH20-)4 C4HgO-(CH2CH2C-)2 CH3 -(CH2CH2 -)3 a B 15 CH30 (CH2CH20 )3 CH30-(CH2CH20-)4H 67 Example 23 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C() OH2C B CHO' .OHC 1 6 tH'c' CH20H CH2 H C 14H9C-CH2CH2-C 145 CH3C-(CH2CH2C-)3 B CH30-(CH2CH20-)3 [ fC14H9C-(CH2CR2C-)3-)1 5' CCH30-(CH2CH20-)5')1.glB 5 zCH3 \ C2H50-(CH2CH20-)3.5-tCHCH2oJl.5 149 Example 24 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2 CR C I B LI CHO .OHC 6tH' CR2 CR2 O ol I 1 4 CR I 14 2 CR2 CHOH CHOH CH20H CH2 H [ (C4HgOCH2CH20~)1 5, {CH30-(CH2CH20-)5-}1 5 ] B 10 [ (C14R9C-(CH2CH2O-)2-}1 5' CCH30-(CH2CH20-)3 1-5 36 C3H70-(CH2CH20-)3H 50

Example 25 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition

% by weight CH20X( ~ )/ OH2Ct / Bss (+) I CHO OR S+R 2 HOCH HCCH CHOH CHOH CH20H CH2CH c H20 C 2, M-M B 2 I / N (+)i CHO OHC I 6+H' I CH2 H CH2 H C4H90-CH2CH20 CH3C-(CH2CR2C-)14 1 146 CH30-(CH2CH20-)4 CH3 CH3 CH3 Example 26 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CR2C() OH2C / 9 CHO CRC 2 6 tH' I CHOH, CH20H HOCH CHOH CH20H CH20 (- > OH2C CHO B+2)I CHO , OHC CRC - - ORO CH2 H CH2 H [ (C4HgO-CH2CH20~)l 5 (CH3 -(cH2cH2 )3 1-5 25 C4H90-(CH2CH20-)35.ih 10 CH30-(CH2CH20-)3H 60

Example 27 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio to form a brake fluid composition.

8 by weight CH20 \(~)/OH2C B OH C CHO OHC OHO CR S +H-2 CH, O 0 C1R CR2 CHOH CHOH CH2 H CH20H

CH2C B OR.C CHO OHC S+R- CR2 Cl H2 1 O O CR2 I CHOH CtSOr. CR2 CR O O CHz CR2 CHOH CHOH CHzOH CH2CH C(C4HgO-CH2CHzO-)1 5, CCH3Q-(C92CH20-)3-r~53B 50 c H,O-(CH2CH20-),H 48

Example 28 Borates and a polyalkylene glycol monoalkyl ether were mixed in the following weight ratio. to form a brake fluid composition.

% by weight CH20 OH2C / (+) l CRC - ORO CHO I 1 1 6 tH' HOCH CHOH I I CH20H HOH2C Cm20\( OR C CHO ,.OH2C 6 6 +H 1 HOCH HOCH CH20H C4HgOCH2CH20 \ CH30-(CH2CH20-)3 B 5 CH30-(CH2CH20-)3 CR C3H7CCHCH2O-(CH2CR2O-)3H 53

Example 29 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CH2C (-B) I )I CHO OHC 10 S+R CH20H CH20H C14H9OCR2cH2o CR30- (CH2CH2O-)3 r a 6 CR3 C- (CR2CR2O-)3 CH90-(CH2CH20-)2 CH30-(CH2CH2 -)3 B CH30 (CH2CH20 )3 /CH,H20-1.5H 11 C3H7o-(cH2cH2o-)3.5-\cHcH2o J1.5 11 C2H50-(CH2CH20-)3H TC

Example 30 Borates and polyalkylene glycol monoalkyl ethers were mixed in the following weight ratio to form a brake fluid composition.

% by weight CI R2CTh.( B I CHO" "OHC 4 1 6 +H' c CH2 H CH2 H CH2O()OH2C Bc) CHO ,OHC 1 6 cH'/ CR2 lH2 2 I I 0 0 I I TICH2 i TICH2 CHOH CHOH CH20H CH2 H [ (C4H O-CH2CH20-)1 5, CH30-(CH2CH20-)4-)1.glB 114 C4 9O (CHcH2 J1 5 ( 2 2 )3 5 10 C2HSO-(CH2CH20-)3H 70

Comparative Example 1 According to United States Patent specification No. 3,625,899, 65% by weight of tris(monomethoxydiethyleneoxyethyl) borate and 35% by weight of triethylene glycol monomethyl ether were mixed to form a brake fluid composition.

Comparative Example 2 According to United States Patent specification No. 3,625,899, 55% by weight of tris(monobutoxydiethyleneoxyethyl) borate and 45% by weight of triethylene glycol monomethyl ether were mixed to form a brake fluid composition.

Comparative Example 3 According to United States Patent specification No. 3,625,899, 70% by weight of fmono(- monobutoxyethyleneoxyethyl), di(monodiethyleneoxyethyl)} borate and 30% by weight of triethylene glycol monomethyl ether were mixed to form a brake fluid composition.

Comparative Example 4 According to United States Patent specification No. 3,625,899, 75% by weight of (poly(1 .5 moles) (monobutoxyethyleneoxyethyl), poly(1.5 moles)(monomethoxydiethyleneoxyethyl)} borate and 25% by weight of triethylene glycol monomethyl ether were mixed to form a brake fluid composition.

The physical properties values of the products of Examples 1 to 30 and Comparative Examples 1 to 4 as well as a commercially brake fluid composition comprising triethylene glycol monomethyl ether are shown in the following table in comparison with the second class, No. 2 standard of JIS K-2233 (Motor Vehicle Brake Fluids) and DOT-4 grade of Federal Motor Vehicles Safety Standard (FMVSS No. 116).

Table

Test Volume* item Kinetic Rubber swelling precipitate Weight of** ERBP WET-ERBP viscosity property (cc) (for precipitate (mg) Example (*C) (*C) at - 40 C (120#2 C, 75 cc of (for 75 cc of No. (760 mmHg) (cst) (cst) 70#2 hour treatment test fluid) test fluid) JIS K-2233 190 or 1800 or Change in base 2nd class more less diameter of SBR No. test cup 0.15-1.4 mm FMVSS 230 or 155 1800 or Change in base DOT-4 more more less diameter of BSR grade test cup 0.15-1.4 mm Example 1 260 170 1326 Change in base 0 0 diameter of cup 0.15 mm Example 2 269.5 167 1612 ,, 0.20 0.08 16 Example 3 266 167 1590 ,, 0.35 0.08 19 Example 4 265 179 1595 ,, 0.25 0.05 5 Example 5 273 183 1705 ,, 0.25 0 0 Example 6 260.5 174.5 1197 ,, 0.35 0.08 15 Example 7 279 185 1792 ,, 0.35 0.03 7 Example 8 263 179 1705 ,, 0.35 0.04 9 Table

Test Volume* item Kinetic Rubber swelling precipitate Weight of** ERBP WET-ERBP viscosity property (cc) (for precipitate (mg) Example (*C) (*C) at - 40 C (120#2 C, 75 cc of (for 75 cc of No. (760 mmHg) (cst) (cst) 70#2 hour treatment test fluid) test fluid) Example 9 279.5 182 1778 ,, 0.20 0 0 Example 10 270 180 1358 ,, 0.20 0.04 11 Example 11 264 185 1715 ,, 0.15 0 0 Example 12 261 159 1297 ,, 0.20 0.06 12 Example 13 276 180.5 1788 ,, 0.35 0.02 4 Example 14 272 179 1702 ,, 0.40 0.09 13 Example 15 265 183 1790 ,, 0.15 0 0 Example 16 263 174 1405 ,, 0.15 0 0 Example 17 270 179 1730 ,, 0.20 0 0 Example 18 268.5 173 1755 ,, 0.20 0.01 2 Example 19 269.5 169 1610 ,, 0.25 0 0 Example 20 268.5 159 1592 ,, 0.25 0.03 8 Example 21 272 180 1787 ,, 0.40 0.06 13 Example 22 267 178 1565 ,, 0.25 0 0 Example 23 270.5 177.5 1716 ,, 0.40 0.09 20 Example 24 268 181 1710 ,, 0.30 0.02 5 Example 25 270 183 1721 ,, 0.30 0 0 Example 26 262 175 1580 ,, 0.20 0.02 4 Example 27 260 170 1289 ,, 0.35 0.08 19 Example 28 267.5 170 1415 ,, 0.40 0.08 20 Example 29 274 169.5 1790 ,, 0.15 0 0 Example 30 261 168 1350 ,, 0.15 0 0 Commercially*** 249 147 252 ,, 0.20 0.3 89 available product Comparative 278 170 1998 ,, 0.55 0.65 118 Example 1 Table

Test Volume* item Kinetic Rubber swelling precipitate Weight of** ERBP WET-ERBP viscosity property (cc) (for precipitate (mg) Example (*C) (*C) at - 40 C (120#2 C, 75 cc of (for 75 cc of No. (760 mmHg) (cst) (cst) 70#2 hour treatment test fluid) test fluid) Comparative 277 155 2087 ,, 1.80 1.40 248 Example 2 Comparative 271 168 2009 ,, 1.75 1.20 203 Example 3 Comparative 269 161 2015 ,, 1.90 1.35 211 Example 4 Notes: * Volume of precipitate was measured by charging 75 ml of a brake fluid after rubber swelling property test into the test tube as described in JIS K-2504 (Lubricating oil Precipitation Number Testing Method) and then centrifuging at 2000 for 30 minutes.

** Weight of precipitate was measured by dispersing the precipitate obtained by said centrifugation in 75 ml of ethyl alcohol to wash the precipitate, repeating the washing operation, and then drying the precipitate at 70 # 2 C for 15 hours to remove ethanol.

*** Trisethylene glycol monomethyl ether.

Claims

1. A brake fluid composition for automobiles comprising as an effective ingredient a mixture of at least one semipolar borate represented by the general formula,

wherein X, X', Y and Y' each are hydrogen atom, a group of the formula,

wherein a is 0, 1, 2 or 3, or a group of the formula,

wherein b is 1 or 2 provided that at least two hydroxyl groups are present in X + X' + Y + Y', at least one heteroborate represented by the general formula, [ fC4H90-(CH2CH2-0-)k-) P . fCH30-(CH2CH20-)1) q ] B (I I) wherein p is a positive number of 1 to 3/2, q is a positive number of 3/2 to 2 and p + q is 3, k is a positive number of 1 to 3, and jis a positive number of 3 to 5, and at least one polyalkylene glycol monoalkyl ether represented by the general formula,

wherein R is a C1-C4 alkyl, lis O or a positive number of 3/2 or less, n is O or a positive number of 3/2 or less, and m is a positive number of 3 to 5 provided that there are the following relationships between I, m and n: 3'(/+ m+ n)5 and

2.A brake fluid composition for automobiles according to Claim 1 comprising as an effective ingredient a mixture of 1 to 10% by weight of at least one semipolar borate represented by the said general formula (1), 9 to 50% by weight of at least one heteroborate represented by the said general formula (II) and 40 to 90% by weight of a polyalkylene glycol monoalkyl ether represented by the said general formula (III).

3. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, (mono(monobutyoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate and triethylene glycol monomethyl ether.

4. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, (mono(monobutoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate and tetraethylene glycol monomethyl ether.

5. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, {mono(monobutoxyethyleneoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate and triethylene glycol monomethyl ether.

6. A brake fluid fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bis(glyceryloxyglyceryl) borate, {mono(monobutoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate and triethylene glycol monomethyl ether.

7. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, (mono(monobutoxyethyl), di(monomethoxytriethyleneoxyethyl)) borate, (mono(monobutoxyethyleneoxyethyl), di(monomethoxydiethyleneoxyethyl)} borate and tetraethylene glycol monomethyl ether.

8. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, fmono(monobutoxyethyl), di(monomethoxydiethyleneoxyethyl)) borate, tetraethylene glycol monomethyl ether and pentaethylene glycol monomethyl ether.

9. A brake fluid composition for automobiles according to Claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, bissorbityl borate, (mono(monobutoxyethyl), di(monomethoxytriethyleneoxyethyl)} borate and triethylene glycol monoisopropyl ether.

10. A brake fluid composition for automobiles according to claim 1 or 2, wherein said mixture as an effective ingredient is a mixture of bisglyceryl borate, bis(glyceryloxyglyceryl) borate, {poly(1.5 moles)(monobutoxyethyl), poly(1.5 moles)(monomethoxytriethyleneoxyethyl)) borate, monobutoxypoly(1 .5 moles) propylene glycol poly (3.5 moles) ethylene glycol ether and triethylene glycol monoethyl ether.

11. A brake fluid composition for automobiles according to Claim 1 as substantially hereinbefore described.