JPS6013892A - Hydraulic fluid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic fluid for transmitting power, particularly a bromine content 0-1 bromine fluid comprising a mixture of glycols of various molecular weights, glycol ethers and boric acid glycol esters as an optional component. The present invention relates to a liquid composition suitable as a pressure brake fluid.

Automotive brake systems represent an important safety element. Efficient operation of brakes is determined to a large extent by the characteristics of the hydraulic fluid used in the brake system. Therefore,
According to current regulations, hydraulic fluids have boiling point, viscosity (at high and low temperatures), pH value, and stability (at high and low temperatures).
Very strict requirements regarding specified properties such as corrosion effects on metals, swelling effects on rubber, etc. will be imposed.

Among the characteristic values listed here, those that are decisive for confirming the suitability or unsuitability of a brake fluid are the total reflux boiling point after humidification (WET PERT) and the viscosity at low temperatures.

Such characteristic values are closely linked to the hygroscopicity of the considered fluid.

In fact, this affinity for water is not only manifested in the absorption of water from the humid surroundings (atmosphere), but also influences the total reflux boiling temperature at atmospheric pressure (Pg) and low-temperature fluidity. This is also clearly demonstrated in the measurement of intramolecular bond strength.

Whatever gradual moisture uptake by the brake fluid occurs, it results in a gradual decrease in boiling point. This boiling point reduction makes the fluid unreliable for use in brakes. This is because modern automobiles generate significant amounts of frictional heat that can cause boiling of the brake fluid, resulting in the formation of a gas phase that negates the incompressibility of the fluid necessary to achieve power transmission. It is from.

Such a phenomenon is bound to occur, so that any fluid reaches a state of unsuitability as the mileage increases. An effective remedy is to periodically change the brake system fluid.

Thus, although the principle of periodic replacement of brake fluid remains valid, the replacement process is not always extremely easy and is at least somewhat costly, making it difficult to reduce the harmful effects of water absorption. As a result, the development of a brake fluid that can extend the operating period under sufficiently suitable conditions has been awaited.

The standard hydraulic brake fluid used is FMVSS 116
, DOT-x and DOT-4 (i.e., Federal Motor Vehicle Safety Standards - Department of Transportation) and SAE J1703 (Automotive Technology Association, N.Y.) must all be met.

Brake fluids belonging to the classification D 01"-3 and DOT-4 have the following characteristic values: DOT-3 DOT-4 Boiling point (dry state) PEI (T min. 205 °C min. 230
6C boiling point (wet state) VVET PEI (T minimum 140°C
Minimum 55℃ viscosity (-40℃) Maximum 150 [1c
St up to 1800 cSt It is known from the patent and technical literature of the past few decades that hydraulic brake fluids as a whole consist mostly of alcohols, glycols, glycol ethers, polyglycols, polyglycol ethers and mixtures of these derivatives.

For example, French Patent No. 2.158.523
) discloses a brake fluid composition belonging to the OT-4 classification consisting of a mixture of tetraethylene glycol, ether glycol and lower glycol ether. This composition has a high low temperature viscosity value (1590 cSt at -40°C, Example 1) due to the presence of tetraethylene glycol.
) and slightly above 155°C.
RT (up to 156, 5°C, Example 2).

It is obvious that too high a viscosity at low temperatures represents a negative characteristic for hydraulic brakes, which jeopardizes the practical use of the brake fluid.

Much research has been carried out in an attempt to obtain a brake fluid whose WE'l' PERT is always higher than 155°C, and whose viscosity at -40°C is not higher than 1500C8t.

The brake fluids referred to as DOT-3 or DOT-4 contain the components of conventional formulations based on glycol-borate esters, especially dialcohols, glycols, glycol ethers, polyglycols and solyglycol ethers. Of these, one or more of these have been selected as partially or completely esterified products with halonic acid.

For example, US Patent No. 5.625.899, the first patent related to oxide ester, is a liquid that is a mixture that is one type at an ether -based glycol, polyglycoles, one type and a mixture of monoethel glycol. A pressure brake composition is disclosed.

At this patent process stage, different streams of research are being pursued. Thus, although these studies differ from each other in the way they emphasize specific types of borate esters, they all require that the composition: 1) contain bromine in the composition in order to enter the OT-4 classification; They have in common that they must exist at a concentration higher than the limiting value.

In this composition, a portion of the absorbed water is removed by the hydrolysis reaction of the ester, with an associated undesirable tendency to precipitation of boric acid.

Furthermore, the organic balate salts used in this method consistently cause swelling of the rubber (esters of ethereal glycols) or high viscosity (esters of glycols), but in any case, comparison with conventional formulations However, it has the disadvantage that it results in unavoidably high costs. For this reason, organic balate-containing formulations have not hitherto been widely available on the market.

Thus, a need was felt for brake fluids that can be DOT-4 in the absence of boronate and, more generally, exhibit excellent moisture resistance properties even in the presence of small amounts of boric esters.

It is therefore an object of the present invention to achieve a WET PERT boiling point higher than 155°C and a
Hydraulic fluids with a viscosity lower than cst (-40°C), i.e. DOT-3 in terms of viscosity, = WETPE
It is an object of the present invention to provide a composition suitable for use as a fluid belonging to RT K12j L, TehaDOT-4.

Another object of the present invention is to provide a borate ester based composition that has higher WET PIMRT values than prior art compositions with the same boron content.

Another object of the invention is that the DOT-3 standard and L) OT
The object of the present invention is to provide a brake fluid that satisfies all of the -4 standards and in particular the non-aggressive standards for metals and rubber present in brake systems. Other objectives and benefits will be apparent to those skilled in the art from the following description.

It has now been found that the object of slanting is surprisingly achieved by a particular liquid composition with a borosine content in the range 0-1% by weight, in which the borosene is in the form of a glycol ester.

More particularly, the hydraulic fluid of the present invention comprises: (a) alkylene glycol 2-4 oi amount % fbJ alkylene glycol monoalkyl ether at least 18 15-6
Polyalkylene glycol monoalkyl ether having the following formula: at least 11 15 to 55% by weight; and (d) at least one boric acid ester of (a) above: 0 to
The composition consists of 54% by weight. (However, all weight percentages refer to the total weight of the hydraulic fluid composition).

Suitable alkylene glycols (al are monomethylene glycol, diethylene glycol, triethylene glycol, monopropylene glycol, diethylene glycol and tripropylene glycol; in particular diethylene glycol and triethylene glycol are preferred.

J This fx alkylene glycol monoalkyl ether (b) is a C1-C4 monoalkyl ether of alkylene glycol (a). Among these, triethylene glycol monoethyl ether is preferred.

Suitable polyalkylene glycol monoalkyl ethers (C) are those in the above formula in which R is C1-C4 alkyl;
1 is H or CH3, and n is the molecular weight of the compound 2
It is a compound that is an integer such as 08 to 1oooH. Preferably, it is a compound where R'=H.

Suitable boric acid esters (d) are the reaction products of boron compounds and alkylene glycols (al). Preferred are the reaction products of boronic acid and diethylene glycol.

The liquid composition obtained by the method of the invention is
Heel T higher than C (lower limit of DOT-4) PER,T,1
Viscosity lower than 500cSt (upper limit of DOT-3) (-
40°C) and a PERT value of about 250°C or higher.

Additionally, the present liquid composition has little or no aggressiveness towards the various metals and rubbers present in brake systems (which is of considerable benefit to the service life of brake systems).
In addition, it has all the typical characteristics of a conventional product of the highest quality.

If desired, additives can be added to the composition of the invention to enhance the performance of the brake fluid.

Such additives include buffering agents, corrosion inhibitors, antioxidants,
Substances that increase protection for ferrous metals in humid oxidizing environments,
There are various types such as stabilizers and dyes.

Generally, the amount of additive that can be incorporated into the liquid composition ranges from 0 to 10X with respect to the total amount of the composition.

The preparation of the 52 ester (a) is carried out at 50° C. under atmospheric pressure (preferably in the presence of an azeotropic solvent) or under reduced pressure (in the absence of a solvent).
It is carried out at temperatures in the range of 200°C.

The hydraulic fluid according to the invention is produced in a mixer with a component (al
, (b), (C1- and (d)) and Addition 1 together until sufficient and complete homogenization is achieved. Generally, this mixing is carried out at atmospheric pressure. It is carried out at lower room temperature, preferably in dry conditions.

The invention is illustrated by the following non-limiting examples.

Example 1 A brake fluid was prepared by mixing together the following components: 56.20 Component (C): Tetraethylene glycol monomethyl ether Z20 Component (d): Pentaethylene glycol monomethyl ether 00 Total: 100.00 This brake The fluid has the following properties: Boiling point at total reflux (PERT) Boiling point after humidification (WE'l') at 250°C
PiT) 161℃ - Viscosity (-40℃) 1276C8
t - Viscosity (+100°C) 24 cSt - Vapor containment temperature (VLT) ) 250°C - Vapor containment temperature + 0.5% H20223°C - pH, 10,7 ~ High temperature stability Test passed - Chemical stability " - Corrosion (weight) Change, m9/ctrt2): iron stanride
−0,01 Measures −0,01 Aluminum −〇,01 Cast iron +0.06 Copper −0,10 Yellow @ −0,13 −6 hours at 50°C − Allowance for water − Evaporation (relative to the weight of the substance to be evaporated) Weight
±001 Aluminum -0,01 - Effect on rubber Test passed - Simulated service test (Note 2) The characteristic values of the above and the following examples are:
703, FMVSS 11 (S O, J: v CUN
A NC95 (measured according to the method of S-01 standard.

) For comparison, Example 1 of French Patent No. 2, J58,525, which discloses the preparation of a mixture having the following composition, was repeated.

Parts Tetraethylene glycol 3o7゜Triethylene glycol monomethyl ether 55.0
Diethylene glycol 150 Diptylamine 06 JAge Rite Re5in D J O,1 Sodium nitrate 0.02 Total: 100.42 parts 1565°C - Viscosity (-40°C) 1585 cSt Example 2 A hydraulic fluid was prepared by mixing together the following components: Component (a):) Diethylene glycol 60.0% component (bl: Triethylene glycol monomethyl Ether 600% Component (C): Tetraethylene glycol monomethyl ether 3!1.OX Component (d): Hentaethylene glycol monomethyl ether 4.0X Total: 1 (10,00%) This fluid showed the following characteristics Total reflux boiling point 266°C - Boiling point after humidification 159°C - Viscosity (-40°C) 1192 cst - Cold flow properties and appearance Test Passing Example 3 A hydraulic fluid was prepared by mixing together the following components: Components ( a): Diethylene glycol 25.0% Component (b) Nitriethylene glycol monomethyl ether 30.0% Component (C): Tetraethylene glycol monomethyl ether 16.0% Component (C): Hentamethylene glycol monomethyl ether 2.ON Total: 1oo, oo% This fluid showed the following characteristic values: Total reflux boiling point 249°C - Boiling point after humidification 158°C - Viscosity (-40°C) 1178 cst - Steam confinement temperature 〉250°C - Vapor confinement temperature +0. 5% H20219℃-evaporation (X
Part/Part) 65 Example 4 A hydraulic fluid was prepared by mixing the following components: Component (a): Diethylene glycol 30.0% Component (bl: )Lyethylene glycol monomethyl ether 30.0% Total: 1oo, oo % This fluid showed the following characteristic values: Total reflux boiling point 246°C - Boiling point after humidification 160°C - Viscosity (-40°C) 1264 cst - Low temperature fluidity and appearance Test passing example 5 Hydraulic fluid was prepared with the following components. Prepared by mixing together: Component (a): Diethylene glycol 30.0% Component (b) Nitriethylene glycol 43.0% Total: 1
0.00 H202 19°C - Low Temperature Flowability and Appearance - Test Pass Example 6 A hydraulic fluid with 0.1% boron content was prepared by mixing together the following components: Weight % Component (a): Diethylene glycol 22.00X Total: 1oo, oo% This fluid showed the following characteristic values Total reflux 249°C - Boiling point after humidification 161°C - Viscosity (-40°C) 11415 cSt For comparison,
containing an equal amount (approximately 0.1%) of boron, similar to that described in Example 3 of French Patent No. 2,158,524;
A fluid having the following composition was also prepared: Part % - Tetraethylene glycol 37 - 2-Triethylene glycol monobutyl ether/l/20.0 - Triethylene glycol monomethyl ether 67.8 -
Age Rite Re5in D Q, 1- Sodium Nitrate 0.02 Total: 1oo, oo parts% The following characteristic values were measured for the fluid thus obtained.
Total reflux boiling point 246°C - Boiling point after humidification 156°C - Viscosity (-40°C) 1360 cst Example 7 A hydraulic fluid with a 0.46% borosine content was prepared by mixing together the following components: Ingredients (a): Diethylene glyco-# 8.2% component (
b) Nitriethylene glycol monomethyl ether 53.0% Component (C): Tetraethylene glycol monomethyl ether 20.0% Component (d): Reaction product of HBO and diethylene glycol (Syl'Ih 1:3) 13.8 % total: 1
oo, oo% This fluid showed the following characteristic values: Total reflux boiling point 252°C - Boiling point after humidification 167°C - Viscosity (-40°C) 1096 cSt For comparison, French Patent No. 2.158.522 According to example 1,
An equal amount of 0.46% of borine was prepared by preparing a fluid consisting of the following components. , l-1-ethylene glycol monomethyl ether 75 parts% The following characteristic values were measured for the fluid thus obtained: Total reflux boiling point 264°C - Boiling point after humidification 159°C - Viscosity (-40°C) 1030 cst Example 8 Boron A hydraulic fluid with a content of 0.5X was prepared by mixing together the following components: Component (a) Nidiethylene glycol 8.0% Component (b
): ) Diethylene glycol monomethyl ether 5
2.0% Component (C): Tetraethylene glycol monomethyl ether 20 parts% Component (C): Hentaethylene glycol monomethyl ether 5.0% Component (d): HBO and diethylene glycol (3E
Reaction product with -ru b 1:3) 15.0X100.
00% This fluid showed the following characteristic values Total reflux boiling point 253℃ - Boiling point after humidification 169℃ - Viscosity (-40℃) 1143 cSt Example? A hydraulic fluid with a 0.7X boronate content was prepared by mixing together the following components: Component (a): Diethylene glycol 2.0% component (
b): ) Diethylene glycol monomethyl ether
56.9% Component (C): Tetraethylene glycol monomethyl ether 20 parts% Component "'"": %C, C7'>'b";4'Q"a
e, L 2 t I was prepared by mixing together the following ingredients: Component (a) Nidiethylene glycol 7.2% Component (b)
) : ) IJ Ethylene glycol monomethyl ether 54.0% Component (C): Tetraethylene glycol monomethyl ether 20.0% Component (")" 1j ze♀L 91. -F-VaΩstoichiometry
13.8X Meter: 100.00X This fluid exhibited the following characteristics: Total reflux boiling point 252°C - Boiling point after humidification 162°C - Viscosity (-40°C) 1096 cst - Fluidity and appearance (-50°C): Test Passing Example 11 A hydraulic fluid with a 0.5% borosine content was prepared by mixing together the following components: Component (a): ) Diethylene glycol 6.0% Component (b) Nitriethylene glycol monomethyl Ether 50.8% Component (C): Tetraethylene glycol monomethyl ether A/20.0% Total: 1oo, oo% This fluid showed the following characteristic values: Total reflux boiling point 265℃ - Boiling point after humidification 167℃ - Viscosity (-P40°C) 1546cst - Flowability and Appearance (-50°C) Test Passing Example 12 A hydraulic fluid with a 0.43% boron content was prepared by mixing together the following components: lff1 min (a ): Diethylene glycol 9.00
% component (d): 83H (reaction product of J3 and diethylene glycol (molar ratio 1:3) 12.96% io
o, oo% This fluid showed the following characteristic values: Total reflux boiling point 249°C - Boiling point after humidification 167°C - Viscosity (-40°C) 1092 cst - Fluidity and appearance (-50°C) Test pass For comparison, A fluid similar to that described in Example 68 of U.S. Pat. No. 3,711,410, with a 0.43% borosine content, was prepared consisting of the following basic components: Neat triethylene glycol monomethyl ether 7s, 1 g% - Tetraethylene glycol monomethyl ether 4.70 parts% Total: 99.71 parts% This fluid showed the following characteristic values: Total reflux boiling point 2439C - Boiling point after humidification 162°C

Claims (5)

[Claims] (1) bromine content of 0 to 1% by weight, essentially the following components: 2-40% by weight of an alkylene glycol having the general formula % () (where Ra and
C4 alkyl)
5-65% by weight, C) general formula % formula % () (where R is C4-C4 alkyl, R1 is H or Cd5, n represents the molecular weight of the compound from 208 to 10
d) 15-55% by weight of at least one polyalkylene glycol monoalkyl ether having the following integer range: 1:1.5-3
A hydraulic fluid consisting of a molar ratio of 0 to 54% by weight of the reaction product of H5BO and the alkylene/glycol of general formula (I), and e) 0 to 10% by weight of at least one inhibitor (provided that all weight percent shall be based on the total weight of the hydraulic fluid). (2) In compound C) having formula (Iff), R1
is H, and n represents the molecular weight of the compound from 208 to 340.
A hydraulic fluid as claimed in claim 1, characterized in that the range is an integer. (3) The fluid does not contain back teeth, and a) 23 to 33% by weight of an alkylene glycol selected from diethylene glycol and triethylene glycol.
, b) Triethylene glycol monomethyl ether 20~
45% by weight, and C) at least one polyalkylene glycol monomethyl ether selected from the group consisting of compounds having the general formula (111) with an average molecular weight of 208 to 600.
Hydraulic fluid according to claim 1, characterized in that it consists of % by weight. (4) The fluid contains bromine and consists essentially of the following components: a) Alkylene glycols selected from the group consisting of diethylene glycol and triethylene glycol 2-z
s, 35<i%, b) 40 to 60% by weight of triethylene glycol monomethyl ether, C) polyalkylene glycol monoalkyl ether selected from the group consisting of compounds having the general formula (III) and having an average molecular weight of 208 to 600. At least 1 glaze 15-3
5% by weight, d) 3-34% by weight of a reaction product of 3 moles of an alkylene glycol selected from the group consisting of diethylene glycol and triethylene glycol and 0.1 mole of H5B. Hydraulic fluids as described in Section. (5) Component d) is 3 to 24% by weight based on the total weight of the fluid.
Hydraulic fluid according to claim 4, characterized in that the component is the reaction product of 3 moles of diethylene glycol and 1 mole of H, Bo.