JP2006519887A - DOT4 brake fluid - Google Patents

Abstract

The brake fluid
(A) 10 to 50% by weight, preferably 20 to 40% by weight, of diethylene glycol and / or dipropylene glycol
And (b) one or more monoalkyl ethers of (poly) ethylene glycol and / or (poly) propylene glycol, 50 to 90% by weight, preferably 60 to 80% by weight
Containing. The brake fluid of the present invention contains no borate and is suitable for use in areas with high relative humidity due to its low hygroscopicity.

Description

The present invention relates to a novel DOT4 brake fluid that does not require the addition of borates (borate esters). The brake fluid is (a) 10 to 50% by mass of diethylene glycol and / or dipropylene glycol.
And (b) (poly) ethylene glycol monoalkyl ether and / or (poly) propylene glycol monoalkyl ether 50-90% by weight
And preferably free of polyglycol dialkyl diethers.

  Hydraulic fluids and especially automotive brake fluids place very high demands on chemical and physical properties. Due to the existing standards and standards for brake fluids of the US Department of Transportation (DOT) in the Federal Motor Vehicle Safety Standard (FMVSS) No. 116 and the standard SAEJ 1704 published by the Automotive Engine Association, modern brake fluids It should have a high equilibrium reflux boiling point (ERBP) and a high wet ERBP, while having a viscosity that varies only slightly within a wide temperature range.

Therefore, it is necessary to satisfy the standard values shown below for the DOT4 brake fluid according to FMVSS No. 116.
ERBP: 230 ° C. or higher, wet ERBP: 155 ° C. or higher, viscosity at −40 ° C .: 1800 mm ² / s or lower.

  Furthermore, there are more stringent demands for sufficiently good protection of metals and non-ferrous metals from corrosion due to brake fluid, which can be achieved by corrosion inhibitor additives contained in the brake fluid. Commercially available DOT4 brake fluid always contains a borate ester, such as methyl triglycol borate, which can chemically remove a predetermined amount of permeating water from the brake fluid by hydrolysis. One drawback is that borate esters are hygroscopic per se, and as a result DOT4 brake fluid absorbs a lot of water very quickly, especially in high relative humidity areas, such as tropical and subtropical areas, and captures borate esters. Despite its function, it can adversely affect the working capacity of brake equipment filled with borate esters.

  U.S. Pat. No. 3,625,899 contains at least one borate ester 54.5-92%, polyalkylene glycol up to 20%, and polyglycol monoalkyl ether or polyglycol dialkyl ether 3-43%, plus other additives DOT4 brake fluid to be described.

  U.S. Pat. No. 3,972,822 describes a DOT4 brake fluid containing 40-65% polyglycol monoalkyl ether, 16-45% polyglycol, and 10-19% borate ester, and further containing a corrosion inhibitor.

  WO 00/46325 describes a DOT4 brake fluid containing methyl triglycol borate, glycol ether and glycol in different amounts and further containing additives.

  WO 02/38711 also discloses corresponding DOT4 brake fluids containing various methyl polyglycol borates, polyglycol monoalkyl ethers, and corrosion inhibitors.

  German Patent No. 3627432 describes a borate-free brake fluid containing 30-80% glycol component and up to 70% polyglycol alkyl ether. The glycol component contains 0 to 80%, 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 DOT4 standard at selected mixing ratios. One drawback with these compositions is that the ERBP value is slightly above the specification limit, in particular, uses polyglycol dialkyl ethers, which are expensive to synthesize and are incompatible with rubber and sealants It often causes a reaction.

  Furthermore, a low-viscosity brake fluid that satisfies the DOT4 standard is required.

  An object of the present invention is to provide the brake fluid. Advantageously, this brake fluid is not very hygroscopic and should be usable in areas of high relative humidity. In particular, it should be necessary to use small amounts of boric acid esters or the use of these esters should not be necessary at all.

The problem is
(A) 10 to 50% by mass of diethylene glycol and / or dipropylene glycol
And (b) one or more of a monoalkyl ether of (poly) ethylene glycol or (poly) propylene glycol 50 to 90% by mass
It is solved by the brake fluid containing

  In particular, the liquid of the present invention does not contain a borate ester.

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

  Diethylene glycol and / or dipropylene glycol is present in the new brake fluid in an amount of 10 to 50% by weight, preferably 20 to 40% by weight.

  Another component of the brake fluid of the present invention comprises one or more monoalkyl ethers of (poly) ethylene glycol and / or (poly) propylene glycol, and the substance is 50 to 90% by mass in the liquid of the present invention. It is preferably present in an amount of 60 to 80% by weight.

  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, triethylene glycol and / or tetraethylene glycol are preferred.

The alkyl groups in the monoalkyl ethers of (poly) ethylene glycol and (poly) propylene glycol used according to the invention are preferably linear or branched C ₁ -C ₆ -alkyl groups. Linear or branched _C 1 -C ₄ - alkyl groups such as methyl, ethyl, isopropyl, n- propyl, n- butyl, more advantageous to use isobutyl, s- butyl or t- butyl, .

  Alkyl groups are in particular methyl, ethyl, isopropyl or n-butyl.

  In the present invention, methyldiethylene glycol, methyltriethylene glycol, methyltetraethylene glycol and / or butyltriethylene glycol are preferred.

  The brake fluid of the present invention has a wet ERBP value, in particular an ERBP value close to the ERBP value achieved to date using a borate-free brake fluid. This value is comparable to that currently achieved only using a borate-containing liquid. However, due to the absence of borate, the liquids of the present invention are much less hygroscopic than the borate-containing liquids. This is particularly advantageous during use in tropical and subtropical regions, since water is absorbed much faster, even though some water is combined by the addition of borate. This causes a deterioration of the characteristics of the brake fluid in each case. In particular, this loss of properties occurs frequently in automobile brake systems and also during liquid storage and transport. The brake fluid of the present invention does not have the above drawbacks.

  It is certainly true that the brake fluid of the present invention may contain various amounts of boric acid ester. However, this does not generally achieve the advantage of the present invention of low hygroscopicity. This is especially the case when boric acid esters are added in the usual amounts according to the state of the art.

  Furthermore, the liquids according to the invention do not contain polyalkylene glycol dialkyl ethers in particular. Despite the fact that the ether can be present in various amounts, the advantages of the brake fluids of the present invention, in particular the compatibility between the rubber and the sealing agent, are generally not achieved, which of course depends on the amount of polyalkylene glycol dialkyl ether present. Dependent.

  Polyglycols may further be present as an optional component in the composition of the present invention. Preference is given to using the rather high boiling point reaction products of ethylene oxide and / or propylene oxide and / or butylene oxide with water or diol. In particular, a reaction product of water with a mixture of ethylene oxide and propylene oxide is used. The number of alkylene oxide units in the polyglycol is generally from 2 to 10, preferably 2 or 3, and is present in an amount of up to 5%.

  The action of these high boiling polyglycols is that of a lubricant and is due to a significant improvement in temperature-viscosity characteristics. Polyglycols often impart sufficient viscosity to polyglycol monoalkyl ethers having low viscosity at high temperatures to ensure sufficient lubricity. Sufficient lubricity is desirable because parts of automobile brake systems require that rubber or elastomers slide on metal with very little wear.

  In another embodiment, the new DOT4 brake fluid for automobiles further comprises 0.001 to 10% by weight of one or more corrosion inhibitors, preferably 0.005 to 4% by weight, in particular 0.005 to 1% by weight, For example, 1H-1,2,3-benzotriazole, 1H-1,2,3-tolutriazole, hydrogenated 1H-1,2,3-tolutriazole, benzimidazole and / or its Derivatives, alkali metal salts of phosphoric acid and phosphorous acid, fatty acids, preferably caprylic acid, lauric acid, palmitic acid, stearic acid or oleic acid and their alkali metal salts, esters of phosphoric acid and phosphorous acid, preferably phosphorus Ethyl phosphate, dimethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphite, or dimethyl phosphite, ethoxylated Good monoalkylamines and dialkylamines and salts of said amines with inorganic acids and fatty acids, preferably butylamine, hexylamine, octylamine, isononylamine, oleylamine, dipropylamine, diisopropylamine or dibutylamine, ethoxylated Good alkanolamines, preferably mono-, di- or triethanolamine, N, N'-di-n-butylaminoethanol or 1,1'-iminodipropan-2-ol, cyclohexylamine and / or nitroaromatic Group compounds, preferably 3-nitrobenzaldehyde.

  The brake fluid of the present invention has the following formula described in WO 01/90281:

（式中、
（ｉ）ＸがＮであり、ＹがＣＲであり、ＺがＮであるか、または
（ｉｉ）ＸがＮであり、ＹがＮであり、ＺがＮまたはＣＲであるか、または
（ｉｉｉ）ＸがＣＲであり、ＹがＮであり、ＺがＮであり、
Ｒはそれぞれ存在する他の基Ｒと独立に、水素原子または基Ｒ^１であり、
Ｒ^１はそれぞれ存在する他の基Ｒ^１と独立にアルキル、アリール、アラルキル、ハロゲン、ハロゲンアルキル、非置換またはアルキル、アリールまたはアラルキルで置換されたアミノ、複素環の基、シアノ、カルボキシ、アルコキシカルボニル、ヒドロキシルまたはアルコキシであり、前記有機基Ｒ^１はそれぞれ１〜３０個の炭素原子を有し、
ｎは０，１または２である）を有する１種以上の複素環式化合物を含有することができる。この種の有利な化合物の例はプリン、アデイニン、６−クロロプリン、２，６−ジクロロプリン、６−メトキシプリン、１Ｈ−１，２，３−トリアゾロ［４，５ｂ］ピリジン、６−ヒスタミノプリンおよび６−フルフリルアミノプリンを含む。

(Where
(I) X is N and Y is CR and Z is N; or (ii) X is N and Y is N and Z is N or CR; or (iii) ) X is CR, Y is N, Z is N,
R is independently a hydrogen atom or group R ¹ independently of the other groups R present,
R ¹ is independently of each other group R ¹ present alkyl, aryl, aralkyl, halogen, halogenalkyl, unsubstituted or alkyl, aryl or aralkyl substituted amino, heterocyclic group, cyano, carboxy, alkoxycarbonyl , Hydroxyl or alkoxy, the organic radicals R ¹ each having 1 to 30 carbon atoms,
n may be 0, 1 or 2). Examples of advantageous compounds of this type are purine, adenine, 6-chloropurine, 2,6-dichloropurine, 6-methoxypurine, 1H-1,2,3-triazolo [4,5b] pyridine, 6-histamino. Contains purine and 6-furfurylaminopurine.

  The borate-free DOT4 brake fluid of the present invention can further contain a composition containing 1H-1,2,4-triazole described in WO02 / 081604.

  The brake fluid according to the invention is additionally described in the general formula I described in WO 00/65001.

（式中、
Ｘは酸素原子または式Ｎ−Ｒ^１の基であり、
Ｒ^１は水素または直鎖状または分枝状Ｃ_１〜Ｃ_２０−アルキル基であり、前記基は付加的に９個までの隣接しない酸素原子により中断されていてもよくおよび／または６個までのヒドロキシル基を有することができ、またはシクロアルキル基、または置換されていないかまたは置換されたフェニル基であり、
Ａは式−ＣＲ^２Ｒ^３−の基であり、
Ｒ^２およびＲ^３はそれぞれ水素原子またはＣ_１〜Ｃ_８−アルキル基であり、前記基は付加的に４個までの隣接しない酸素原子により中断されていてもよくおよび／または３個までのヒドロキシル基を有することができ、
ｎは２〜７である）を有する環状カルボン酸誘導体を含有することができる。

(Where
X is an oxygen atom or a group of formula N—R ¹ ;
R ¹ is hydrogen or a linear or branched C ₁ -C ₂₀ -alkyl group which may additionally be interrupted by up to 9 non-adjacent oxygen atoms and / or up to 6 Or a cycloalkyl group, or an unsubstituted or substituted phenyl group,
A is a group of the formula —CR ² R ³ —
R ² and R ³ are each a hydrogen atom or a C ₁ -C ₈ -alkyl group, which group may additionally be interrupted by up to 4 non-adjacent oxygen atoms and / or up to 3 hydroxyl groups Can have groups,
n is 2 to 7).

  These are suitable as components that reduce the low-temperature viscosity in the presence of water.

  Other components and auxiliaries in the new automotive brake fluids are conventional antioxidants such as those based on phenothiazine and / or phenol and conventional antifoams and markers.

  All mass percentages already described and described below relate to the total amount of hydraulic fluid or brake fluid, respectively.

  The borate-free DOT4 brake fluid according to the invention satisfies the requirements described at the outset in an excellent manner and furthermore has generally good corrosion properties compared to the state of the art: iron, steel, tin plate, cast iron Cast iron), in the case of metals such as lead, tin, chromium, zinc, aluminum, magnesium and their alloys and in the case of solder metals such as tin solder, and non-ferrous metals such as copper and their alloys such as brass In some cases, very good corrosion protection is guaranteed.

  Besides the significantly reduced moisture absorption properties due to the absence of borate, other advantages of the new automotive DOT4 brake fluid that can be described are: advantageous low temperature viscosity, good water compatibility, mild pH value, good low temperature Stability, high temperature stability, and oxidation stability, and good chemical stability, advantageous properties for materials such as rubber, plastics, glue joints, fibers, elastomers and rubber seals and similar materials (ie good phase Solubility) and good lubricating properties.

  The following examples illustrate the invention but do not limit the invention.

Use Example The used borate-free DOT4 brake fluid BF1 of the present invention had the following composition.

Inventive Example BF1:
Diethylene glycol 31.0%
Mixture of methyl diglycol, butyl diglycol, butyl triglycol and methyl tetraglycol 67.7%
1,1'-iminodipropan-2-ol, bisphenol A, toltriazole and 1.3% 3-nitrobenzaldehyde.

Comparative Example BF2
(Equivalent to Example 5 from German Patent No. 3627432 C2)
Diethylene glycol 39%
Triethylene glycol 26%
Triethylene glycol dimethyl ether 24%
Methyl triglycol 10%
Corrosion inhibitor (using 1,1'-iminodipropan-2-ol) 1%.

Physical data
BF1 BF2 (comparative example)
ERBP [° C.] 251 234
Wet ERBP [° C.] 159 153
(Water absorption 3.27% (Water absorption 3.93%
Reference RM713.73%) Reference RM713.70%)
Viscosity-40 ° C: 1393 1277
[Mm / s]
Compared to the state of the art according to DE 3627432 C2, the borate-free DOT4 brake fluid according to the invention has a particularly high ERBP value, which in the case of BF1 easily exceeds the minimum requirement according to FMVSS No 116 by 20 ° C. Furthermore, it has a low water absorption rate and a high wet ERBP value associated therewith.

  The brake fluid according to the invention also gives a very good corrosion protection as indicated by the following results for BF1.

Corrosion test by SAEJ1704, 120 hours / 100 ° C continuous test metal Mass change Appearance
[Mg / cm ² ]
Tin plate ± 0.000 unchanged steel +0.01 unchanged aluminum ± 0.00 unchanged cast iron +0.04 unchanged brass -0.05 slightly hazy copper -0.05 slightly hazy zinc +0 0.03 Cloudy pH value before / after test: 9.9 / 9.6.

Claims (12)

(A) 10 to 50% by weight, preferably 20 to 40% by weight, of diethylene glycol and / or dipropylene glycol
And (b) one or more monoalkyl ethers of (poly) ethylene glycol and / or (poly) propylene glycol, 50 to 90% by weight, preferably 60 to 80% by weight
Containing brake fluid.   The liquid according to claim 1, which does not contain a borate ester.   The liquid according to claim 1 or 2, which does not contain polyalkylene glycol dialkyl ether.   4. The liquid according to claim 1, wherein diethylene glycol is used as component a).   In component b), the glycol is monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, monopropylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, and The liquid according to claim 1, which is selected from hexapropylene glycol. In component b), the alkyl group is a linear and branched C ₁ -C ₆ -alkyl group, preferably a linear and branched C ₁ -C ₄ -alkyl group, in particular methyl, ethyl, isopropyl and n 6. Liquid according to any one of claims 1 to 5, selected from butyl.   7. A liquid according to any one of claims 1 to 6, wherein component b) is selected from methyl diethylene glycol, methyl triethylene glycol, methyl tetraethylene glycol, and butyl triethylene glycol.   Further reaction products of ethylene oxide and / or propylene oxide and / or butylene oxide with water or diol, preferably with a mixture of ethylene oxide and propylene oxide, having 2 to 10 alkylene oxide units, preferably 2 to 3 8. A liquid according to any one of claims 1 to 7, wherein a product is present.   9. Liquid according to claim 1, wherein 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 are present. .   Corrosion inhibitors are 1H-1,2,3-benzotriazole, 1H-1,2,3-tolutriazole, hydrogenated 1H-1,2,3-tolutriazole, benzimidazole and / or its derivatives, phosphoric acid and Alkali metal salts of phosphorous acid, fatty acids, preferably caprylic acid, lauric acid, palmitic acid, stearic acid or oleic acid, their alkali metal salts, esters of phosphoric acid and phosphorous acid, preferably ethyl phosphate, phosphoric acid Dimethyl, isopropyl phosphate, diisopropyl phosphate, butyl phosphite or dimethyl phosphite, mono- and dialkylamines which may be ethoxylated, and their salts with inorganic acids and fatty acids, preferably butylamine, hexylamine , Octylamine, isononylamine, oleylamine, dipropylamine, Isopropylamine, or dibutylamine, alkanolamines which may be ethoxylated, preferably mono-, di- or triethanolamine, N, N'-di-n-butylaminoethanol or 1,1'-iminodipropane -2-ol, cyclohexylamine, and / or nitroaromatic compounds. 10. Liquid according to any one of claims 1 to 9, preferably selected from the group consisting of 3-nitrobenzaldehyde. The following standard value (DOT4)
ERBP: 230 ° C or higher,
Wet ERBP value: 155 ° C or higher,
The liquid according to any one of claims 1 to 10, which satisfies a viscosity at -40 ° C of 1800 mm ² / s or less.   12. Use of a liquid according to any one of claims 1 to 11 as brake fluid in a motor vehicle, preferably in an area of high relative humidity.