DE10310757A1 - Brake fluid, used in motor vehicles, especially in regions with high humidity, comprises diethylene glycol and/or dipropylene glycol and (poly)ethylene glycol and/or (poly)propylene glycol monoalkyl ether - Google Patents

Abstract

Brake fluid comprises 10-50 wt.% diethylene glycol and/or dipropylene glycol and 50-90 wt.% (poly)ethylene glycol and/or (poly)propylene glycol monoalkyl ether.

Description

• (a) 10 bis 50 Gew.-% Diethylenglykol und/oder Dipropylenglykol und
• (b) 50 bis 90 Gew.-% (Poly)Ethylen- und/oder (Poly)Propylenglykolmonoalkylether

und sind vorzugsweise frei von Polyglykoldialkylethern.The present invention relates to new DOT 4 brake fluids in which the addition of borates (boric acid esters) is not necessary. The brake fluids included

• (a) 10 to 50% by weight of diethylene glycol and / or dipropylene glycol and
• (b) 50 to 90% by weight of (poly) ethylene and / or (poly) propylene glycol monoalkyl ether

and are preferably free of polyglycol dialkyl ethers.

Hydraulic fluids and especially brake fluids for motor vehicles are subject to their chemical and physical properties very high requirements. According to existing standards and Specifications for brake fluids from the U.S. Department of Transportation (DOT) in the Federal Motor Vehicle Saftey Standard FMVSS no. 116 and that of the Society of Automotive Engineers issued the SAE J 1704 standard aimed at modern brake fluids on the one hand about high dry boiling points (reflux boiling points, dry [Equilibrium reflux boiling point, "ERBP"]) and high wet boiling points (reflux boiling points, moist ERBP "]), on the other hand but also a viscosity have that only within a wide temperature range little changes.

• Trockenkochpunkt „ERBP": ≥ 230°C
• Nasskochpunkt „wet ERBP": ≥ 155°C
• Viskosität bei –40°C: ≤ 1800 mm²/s

For a DOT 4 brake fluid according to FMVSS no. 116, the specification values listed below must therefore be observed:

• Dry boiling point "ERBP": ≥ 230 ° C
• Wet cooking point "wet ERBP": ≥ 155 ° C
• Viscosity at –40 ° C: ≤ 1800 mm ² / s

There are also more extensive ones Requirements for adequate corrosion protection for metals and non-ferrous metals from brake fluids, what can be achieved with the anti-corrosion additives it contains can.

Standard DOT 4 brake fluids always contain boric acid esters such as methyl triglycol borate, the penetrating water in certain amounts from the brake fluid chemically by hydrolysis can eliminate. The disadvantage here is that boric acid esters themselves are hygroscopic, causing such DOT 4 brake fluids especially in regions with high humidity, for example so much moisture very quickly in tropical and subtropical areas be able to record, that in spite of the absorption function of the boric acid ester the functionality one filled with it Brake system adversely affected can be.

In the US 3,625,899 DOT 4 brake fluids are described which contain 54.5 to 92% of at least one boric acid ester, up to 20% polyalkylene glycols and 3 to 43% polyglycol monoalkyl or dialkyl ethers in addition to other additives.

The US 3,972,822 describes DOT 4 brake fluids which contain 40 to 65% polyglycol monoalkyl ether, 16 to 45% polyglycols and 10 to 19% boric acid ester plus corrosion inhibitors.

WO 00/46325 describes DOT 4 brake fluids described the methyl triglycol borate, glycol ethers and glycols in contain different amounts and an additive system.

Corresponding are also in WO 02/38711 DOT 4 brake fluids discloses the different methyl polyglycol borates, polyglycol monoalkyl ethers as well as corrosion inhibitors.

In the DE 36 27 432 C2 Borate-free brake fluids of 30 to 80% of a glycol component and up to 70% polyglycol alkyl ethers are described. The glycol component in turn contains 0 to 80% by weight, preferably 55 to 80% by weight, of diethylene glycol and / or dipropylene glycol. The polyglycol alkyl ether component contains 0 to 90% by weight, preferably 0 to 50% by weight, of at least one polyglycol monoalkyl ether. These liquids meet the DOT 4 specification in selected mixing ratios. Disadvantages of these formulations are, in particular, the dry boiling point “ERBP”, which is just above the specification limit, and also the use of complex polyglycol dialkyl ethers which are difficult to synthesize and which often also lead to incompatibility reactions of rubber and sealing materials.

There is still a need for low-viscosity brake fluids, which is the DOT 4 specification fulfill.

The object of the present invention is to provide such a brake fluid. This brake fluid should preferably be less hygroscopic and in regions with high air humidity be settable. In particular, the conversion should only require small amounts of boric acid esters or ideally even be completely unnecessary.

• a) 10 bis 50 Gew. % Diethylenglykol und/oder Dipropylenglykol und
• b) 50 bis 90 Gew.-% einen oder mehrere Monoalkylether von (Poly)Ethylenglykol

oder (Poly)Propylenglykol.This object is achieved by containing a brake fluid

• a) 10 to 50 wt.% Diethylene glycol and / or dipropylene glycol and
• b) 50 to 90% by weight of one or more monoalkyl ethers of (poly) ethylene glycol

or (poly) propylene glycol.

In particular, the liquids according to the invention are free of boric acid esters.

It can be diethylene glycol or dipropylene glycol or a mixture of diethylene glycol and dipropylene glycol in one any ratio be used. Diethylene glycol is preferred.

Diethylene glycol and / or dipropylene glycol are in the brake fluids according to the invention in an amount of 10 to 50% by weight, preferably 20 to 40% by weight. % available.

Another component of the brake fluids according to the invention are one or more monoalkyl ethers of (poly) ethylene glycols and / or (Poly) propylene glycols in the liquids according to the invention in an amount of 50 to 90% by weight, preferably 60 to 80% by weight, are present.

Examples of suitable (poly) ethylene glycols are monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, Pentaethylene glycol and hexaethylene glycol.

Examples of suitable (poly) propylene glycols are monopropylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, Pentapropylene glycol and hexapropylene glycol.

Diethylene glycol and triethylene glycol are preferred and / or tetraethylene glycol.

The alkyl radical in the monoalkyl ethers of (poly) ethylene glycol and (poly) propylene glycol used according to the invention is preferably a linear or branched C ₁ -C ₆ -alkyl radical. It is more preferred to use a linear or branched C ₁ -C ₄ alkyl radical, for example methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, sec-butyl or tert-butyl.

In particular, the alkyl radicals Methyl, ethyl, i-propyl or n-butyl.

Within the scope of the present invention is the use of methyldiethylene glycol, methyltriethylene glycol, Methyl tetraethylene glycol and / or butyl triethylene glycol preferred.

The brake fluids according to the invention have wet boiling points and in particular dry boiling points that lie with those who previously with borate-free brake fluids could be achieved. They are comparable to those that have so far only with liquids containing borate were achieved. Due to the absence of borate, the liquids according to the invention are however, significantly less hygroscopic than those containing borate. This is especially when used in tropical and subtropical areas advantageous because a part of the water due to the borate addition is bound, but water is also absorbed relatively quickly. This means that the brake fluid will deteriorate in any case on. In particular, this loss of quality often occurs in the braking system of motor vehicles, but also when storing and transporting the liquids on. The brake fluids according to the invention do not have the disadvantages mentioned.

The brake fluids according to the invention can boric acid esters contained in different amounts. However, the advantages of the invention the low hygroscopicity generally not achieved. This is particularly the case if the amounts of boric acid esters customary according to the prior art be added.

The liquids according to the invention are also especially free of polyalkylene glycol dialkyl ethers. This too can in different amounts, but then generally the advantages of the brake fluids according to the invention, in particular the compatibility with rubber and sealing materials, this is not achieved here too, of course on the amount of any polyalkylene glycol dialkyl ether present depends.

Additional components can be used as an optional component Contain polyglycols in the formulations according to the invention his. Higher-boiling reaction products of Ethylene oxide and / or propylene oxide and / or butylene oxide with water or diols used. Implementation products from Mixtures of ethylene oxide and propylene oxide with water use. The number of alkylene oxide units in the polyglycols mentioned is usually generally 2 to 10, preferably 2 to 3 and in one Amount up to 5%.

The effect of this high-boiling Polyglycol is that of a lubricant, which essentially indicates a Improvement in temperature-viscosity behavior is attributable. The polyglycols give the polyglycol monoalkyl ethers, which are often viscous at high temperatures enough viscosity and thus ensure adequate lubrication. Adequate lubrication is desirable because rubber or elastomers in the components of the motor vehicle braking system Metal if possible wear have to slide.

In a further embodiment, the DOT 4 brake fluids for motor vehicles according to the invention further contain 0.001 to 10% by weight, preferably 0.005 to 4% by weight, in particular 0.005 to 1% by weight, of one or more corrosion inhibitors, for example 1H-1,2, 3-benzotriazole, 1H-1,2,3-tolutria zole, hydrogenated 1H-1,2,3-tolutriazole, benzimidazole and / or their derivatives, alkali metal salts of phosphoric acid and phosphorous acid, fatty acids, preferably caprylic, lauric, palmitic, stearic or oleic acid and their alkali metal salts, esters of phosphoric acid and phosphorous acid, preferably ethyl phosphate, dimethyl phosphate, isopropyl phosphate, disopropyl phosphate, butyl phosphite or dimethyl phosphite, optionally ethoxylated mono- and dialkylamines and their salts with mineral and fatty acids, preferably butylamine, hexylamine, octylamine, isononylamine, oleylamine, dipropylamine or dibutylamine, diisopropylamine, diisopropylamine, diisopropylamine, optionally ethoxylated alkanolamines, preferably mono-, di- or triethanolamine, N, N'-di-n-butylaminoethanol or 1,1'-iminodipropan-2-ol, cyclohexylamine, and / or nitroaromatics, preferably 3-nitrobenzaldehyde.

in der
(i) x für N, Y für CR und Z für N oder
(ii) X für N, Y für N und Z für N oder CR oder
(iii) X für CR, Y für N und Z für N steht,
wobei
R, jeweils unabhängig von weiteren vorhandenen Resten R, ein Wasserstoffatom oder einen Rest R¹ bezeichnet,
R¹, jeweils unabhängig von weiteren vorhandenen Resten R¹, Alkyl, Aryl, Aralkyl, Halogen, Halogenalkyl, gegebenenfalls alkyl-, aryl- oder aralkylsubstituiertes Amino, einen heterocyclischen Rest, Cyano, Carboxyl, Alkoxycarbonyl, Hydroxyl oder Alkoxyl bedeutet, wobei die genannten organischen Reste für R¹ jeweils 1 bis 30 C-Atome aufweisen, und
n für 0, 1 oder 2 steht, können in den erfindungsgemäßen Bremsflüssigkeiten enthalten sein. Beispiele für bevorzugte Verbindungen dieses Typs umfassen Purin, Adenin, 6-Chloropurin, 2,6-Dichloropurin, 6-Methoxypurin, 1H-1,2,3-Triazolo(4,5B)pyridin, 6-Histaminopurin und 6-Furfurylaminopurin.Also one or more of the heterocyclic compounds of the following general formula described in WO 01/90281

in the
(i) x for N, Y for CR and Z for N or
(ii) X for N, Y for N and Z for N or CR or
(iii) X is CR, Y is N and Z is N,
in which
R, in each case independently of other existing radicals R, denotes a hydrogen atom or a radical R ¹ ,
R ¹ , each independently of other R ¹ radicals present, is alkyl, aryl, aralkyl, halogen, haloalkyl, optionally alkyl, aryl or aralkyl-substituted amino, a heterocyclic radical, cyano, carboxyl, alkoxycarbonyl, hydroxyl or alkoxyl, the abovementioned organic radicals for R ¹ each have 1 to 30 C atoms, and
n stands for 0, 1 or 2, can be contained in the brake fluids according to the invention. Examples of preferred compounds of this type include purine, adenine, 6-chloropurine, 2,6-dichloropurine, 6-methoxypurine, 1H-1,2,3-triazolo (4,5B) pyridine, 6-histaminopurine and 6-furfurylaminopurine.

The borate-free DOT 4 brake fluids according to the invention can furthermore the formulations described in WO 02/081604 with 1H-1,2,4-triazole contain.

enthalten, in der
X für ein Sauerstoffatom oder eine Gruppierung der Formel N-R¹ steht, wobei
R¹ Wasserstoff oder eine lineare oder verzweigte C₁- bis C₂₀-Alkylgruppe bezeichnet, welche noch zusätzlich durch bis zu 9 nicht benachbarte Sauerstoffatome unterbrochen sein und/oder bis zu 6 Hydroxylgruppen tragen kann, oder eine Cycloalkylgruppe oder eine gegebenenfalls substituierte Phenylgruppe bezeichnet,
A eine Gruppierung der Formel -CR²R³- bezeichnet, wobei
R² und R³ für Wasserstoff oder C₁- bis C₈-Alkylgruppen stehen, welche noch zusätzlich durch bis zu 4 nicht benachbarte Sauerstoffatome unterbrochen sein und/oder bis zu 3 Hydroxylgruppen tragen können, und
n eine Zahl von 2 bis 7 bedeutet.In addition, the brake fluids according to the invention can contain the cyclic carboxylic acid derivatives of the general formula I listed in WO 00/65001

included in the
X represents an oxygen atom or a grouping of the formula NR ¹ , where
R ¹ denotes hydrogen or a linear or branched C ₁ to C ₂₀ alkyl group which can additionally be interrupted by up to 9 non-adjacent oxygen atoms and / or can carry up to 6 hydroxyl groups, or denotes a cycloalkyl group or an optionally substituted phenyl group,
A denotes a grouping of the formula -CR ² R ³ -, wherein
R ² and R ^{3 represent} hydrogen or C ₁ - to C ₈ -alkyl groups which can additionally be interrupted by up to 4 non-adjacent oxygen atoms and / or can carry up to 3 hydroxyl groups, and
n represents a number from 2 to 7.

These are components of humiliation the low temperature viscosity suitable in the presence of water.

Other components and tools in the brake fluids according to the invention for motor vehicles can be common antioxidants such as. Phenothiazine and / or those based on phenol, and conventional defoamers as well Dyes.

All of the above and following % By weight refer to the total amount of hydraulic liquid or the brake fluid.

The borate-free DOT 4 brake fluids according to the invention excellently meet the requirements mentioned at the outset and also have a generally good corrosion behavior compared to the prior art, ie very good corrosion protection is applied to metals such as iron, steel, tinplate, cast iron (gray cast iron), Lead, tin, chrome, zinc, aluminum, magnesium and their alloys and in the case of solder metals, for example solder, and in the case of non-ferrous metals such as copper and their alloys, for example brass.

In addition to the freedom from borates are significantly reduced hygroscopic properties than others Advantages of the DOT according to the invention 4 brake fluids for motor vehicles their cheap Low temperature viscosity, good water compatibility, a gentle pH value, good cold, high temperature and oxidation stability as well good chemical stability, a cheap one Behavior (i.e. good tolerance) across from Materials such as rubbers, plastics, glue joints, fiber, elastomer and rubber seals and the like Highlight materials and good lubrication behavior.

The following examples are intended explain the present invention, without restricting them.

The borate-free DOT 4 brake fluid BF 1 used according to the invention had the following composition: Example BF 1 according to the invention: 31.0% diethylene glycol 67.7% Mixture of methyl diglycol, butyl diglycol, butyl triglycol and. Methyltetrahydrofolic glycol 1.3% Mixture of 1,1'-iminodipropan-2-ol, bisphenol A, tolutriazole and. 3-nitrobenzaldehyde Comparative example BF 2 (corresponds to example 5 from DE 36 27 432 C2 ) 39% diethylene glycol 26% triethylene 24% triethylene 10% methyltriglycol 1 % Corrosion inhibitor (used: 1,1'-iminodipropan-2-ol)

Physical data:

The borate-free DOT 4 brake fluids according to the invention are distinguished from the prior art DE 3627432 C2 in particular due to a significantly higher dry boiling point "ERBP", which for BF 1 exceeds the minimum requirement according to FMVSS No. 116 by a good 20 ° C, as well as a lower water absorption and the associated higher wet boiling point "wet ERBP".

The brake fluids according to the invention also lead to very good corrosion protection, like the results below for BF 1 show:

Corrosion test according to SAE J 1704, test duration 120h / 100 ° C:

Claims (12)

brake fluid containing a) 10 to 50 wt.%, preferably 20 to 40 wt. %, Diethylene glycol and / or dipropylene glycol b) 50 to 90 % By weight, preferably 60 to 80% by weight, of one or more monoalkyl ethers of (poly) ethylene glycol and / or (poly) propylene glycol. liquid according to claim 1, characterized in that these are not boric acid esters contains. liquid according to claim 1 or 2, characterized in that these none Contains polyalkylene glycol dialkyl ether. liquid according to one of the claims 1 to 3, characterized in that as component a) diethylene glycol is used. liquid according to one of the claims 1 to 4, characterized in that in component b) the glycols selected are made of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, Pentaethylene glycol, hexaethylene glycol, monopropylene glycol, dipropylene glycol, Tripropylene glycol, tetrapropylene glycol, pentapropylene glycol and Hexapropylene. Liquid according to one of claims 1 to 5, characterized in that in component b) the alkyl residue is selected from linear or branched C ₁ -C ₆ alkyl radicals, preferably linear and branched C ₁ -C ₄ alkyl radicals, in particular methyl, ethyl , i-propyl or n-butyl. liquid according to one of the claims 1 to 6, characterized in that component b) is selected from methyldiethylene glycol, methyltriethylene glycol, methyltetraethylene glycol and butyl triethylene glycol. liquid according to one of the claims 1 to 7, characterized in that continue reaction products of ethylene oxide and / or propylene oxide and / or butylene oxide with water or diols, preferably reaction products of mixtures of ethylene oxide and propylene oxide with water having 2 to 10, preferably 2 to 3, alkylene oxide units available. liquid according to one of the claims 1 to 8, characterized in that 0.01 to 10 wt.%, Preferably 0.005 to 4% by weight, in particular 0.005 to 1% by weight, one or more Corrosion inhibitors are present. Liquid according to one of claims 1 to 9, characterized in that the corrosion inhibitors are selected from the group 1H-1,2,3-benzotriazole, 1H-1,2,3-tolutriazole, hydrogenated 1H-1,2,3-tolutriazole , Benzimidazole and / or their derivatives, alkali metal salts of phosphoric acid and phosphorous acid, fatty acids, preferably caprylic, lauric, palmitic, stearic or oleic acid and their alkali metal salts, esters of Phosphoric acid and phosphorous acid, preferably ethyl phosphate, dimethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphite or dimethyl phosphite, optionally ethoxylated mono- and dialkylamines and their salts with mineral and fatty acids, preferably butylamine, hexylamine, octylamine, isononylamine, oleylamine, dipropylamine or dibutylamine, optionally ethoxylated alkanolamines, preferably mono-, di- or triethanolamine, N, N'-di-n-butylaminoethanol or 1,1'-iminodipropan-2-ol, cyclohexylamine, and / or nitroaromatics, preferably 3-nitrobenzaldehyde , Liquid according to one of claims 1 to 10, characterized in that it complies with the following specification values (DOT 4): dry boiling point "ERBP": ≥ 230 ° C wet boiling point "wet ERBP": ≥ 155 ° C viscosity at -40 ° C: ≤ 1800mm ² / s Use of a liquid according to one of claims 1 to 11 as a brake fluid in motor vehicles, preferably in areas with high humidity.