U.S. patent application number 10/469770 was filed with the patent office on 2004-06-17 for hydraulic fluids with improved anti-corrosion properties.
Invention is credited to Aydin, Bayram, Fidorra, Uwe, Roida, Michael, Wenderoth, Bernd.
Application Number | 20040116306 10/469770 |
Document ID | / |
Family ID | 7680939 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040116306 |
Kind Code |
A1 |
Wenderoth, Bernd ; et
al. |
June 17, 2004 |
Hydraulic fluids with improved anti-corrosion properties
Abstract
Hydraulic fluids, in particular brake fluids for motor vehicles,
having improved corrosion protection, comprising (a) from 0.005 to
0.125% by weight of 1H-1,2,4-triazole, and (b) from 0 to 10% by
weight of one or more further corrosion inhibitors, where, on
concomitant use of 1H-1,2,3-benzotriazole and/or
1H-1,2,3-tolutriazole and/or derivatives thereof, the weight ratio
between 1H-1,2,4-triazole and the said 1H-1,2,3-triazoles must be
greater than 4:1.
Inventors: |
Wenderoth, Bernd; (Birkenau,
DE) ; Roida, Michael; (Weingarten, DE) ;
Aydin, Bayram; (Ludwigshafen, DE) ; Fidorra, Uwe;
(Wachenheim, DE) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Family ID: |
7680939 |
Appl. No.: |
10/469770 |
Filed: |
September 4, 2003 |
PCT Filed: |
April 3, 2002 |
PCT NO: |
PCT/EP02/03671 |
Current U.S.
Class: |
508/280 ;
508/256; 508/279 |
Current CPC
Class: |
C10M 2215/04 20130101;
C10M 2215/044 20130101; C10M 2209/105 20130101; C10M 2207/04
20130101; C10N 2040/08 20130101; C10M 2215/22 20130101; C10M
2219/108 20130101; C10M 137/02 20130101; C10M 169/04 20130101; C10M
2215/223 20130101; C10M 2209/1085 20130101; C10M 137/12 20130101;
C10M 2215/221 20130101; C10M 133/44 20130101; C10M 2209/104
20130101; C10M 2223/04 20130101; C10M 2215/26 20130101; C10M
2215/30 20130101; C10M 2223/049 20130101; C10M 2215/042 20130101;
C10M 2215/226 20130101; C10M 2227/0625 20130101; C10M 2209/1055
20130101; C10M 2223/065 20130101; C10M 2209/1095 20130101; C10M
2223/10 20130101; C10M 2209/1045 20130101; C10M 2223/06 20130101;
C10M 107/34 20130101; C10M 2209/1065 20130101; C10M 2227/062
20130101; C10M 2223/061 20130101; C10M 2209/1033 20130101; C10M
2223/02 20130101; C10M 2227/061 20130101; C10M 2215/225 20130101;
C10M 105/78 20130101; C10M 2223/042 20130101; C10M 2209/1075
20130101; C10M 2227/0615 20130101; C10M 2215/223 20130101; C10M
2215/223 20130101 |
Class at
Publication: |
508/280 ;
508/279; 508/256 |
International
Class: |
C10M 133/44; C10M
169/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2001 |
DE |
101 17 647.3 |
Claims
We claim:
1. A hydraulic fluid having improved corrosion protection,
comprising (a) from 0.005 to 0.125% by weight of 1H-1,2,4-triazole,
and (b) from 0 to 10% by weight of one or more further corrosion
inhibitors, where, on concomitant use of 1H-1,2,3-benzotriazole
and/or 1H-1,2,3-tolutriazole and/or derivatives thereof, the weight
ratio between 1H-1,2,4-triazole and said 1H-1,2,3-triazoles must be
greater than 4:1.
2. A hydraulic fluid as claimed in claim 1, comprising from 0.005
to 0.08% by weight of component (a).
3. A hydraulic fluid as claimed in claim 1 or 2, comprising
component (a) as the only triazole-based corrosion inhibitor.
4. A hydraulic fluid as claimed in claim 1 or 2, comprising, as
component (b), from 0.001 to 0.5% by weight of one or more
compounds from the group consisting of benzimidazole, hydrogenated
1H-1,2,3-tolutriazole, purine, adenine, 6-chloropurine,
2,6-dichloropurine, 6-methoxypurine,
1H-1,2,3-triazolo(4,5-b)pyridine, 6-histaminopurine and
6-furfurylaminopurine, and, if desired, further corrosion
inhibitors other than (a).
5. A brake fluid for motor vehicles, comprising, as corrosion
inhibitors, components (a) and, if desired, (b) as claimed in any
one of claims 1 to 4.
6. A brake fluid for motor vehicles as claimed in claim 5,
furthermore comprising, besides components (a) and, if desired,
(b), from 0.1 to 97% by weight of one or more polyglycol ethers
and/or boric acid esters thereof.
7. A brake fluid for motor vehicles as claimed in claim 5 or 6,
furthermore comprising, besides components (a) and, if desired,
(b), from 0.1 to 50% by weight of one or more polyglycols.
Description
[0001] The present invention relates to hydraulic fluids, in
particular brake fluids for motor vehicles, having improved
corrosion protection which comprise
[0002] (a) from 0.005 to 0.125% by weight of 1H-1,2,4-triazole,
and
[0003] (b) from 0 to 10% by weight of one or more further corrosion
inhibitors, where, on concomitant use of 1H-1,2,3-benzotriazole
and/or 1H-1,2,3-tolutriazole and/or derivatives thereof, the weight
ratio between 1H-1,2,4-triazole and said 1H-1,2,3-triazoles must be
greater than 4:1.
[0004] Hydraulic fluids and in particular brake fluids for motor
vehicles are subject to very high requirements with respect to
their chemical and physical properties. In accordance with the
existing standards and specifications for brake fluids from the US
Department of Transportation in Federal Motor Vehicle Safety
Standard FMVSS-No. 116 and the SAE J 1704 standard published by the
Society of Automotive Engineers, modern brake fluids should on the
one hand have high dry boiling points (equilibrium reflux boiling
points "ERBP") and high wet boiling points ("wet ERBP"), but on the
other hand should also have a viscosity which changes only slightly
within a broad temperature range.
[0005] In addition, there are more exacting requirements from the
automobile industry for improved corrosion protection in the case
of metals and nonferrous metals. Corrosion inhibitors in brake
fluids have the job of preventing destruction of metallic materials
caused by corrosion.
[0006] The use of 1H-1,2,3-triazoles, such as
1H-1,2,3-benzotriazole or 1H-1,2,3-tolutriazole, as corrosion
inhibitors in hydraulic fluids or brake fluids has been known for
some time, for example from EP-A 028 789 (1) and EP-A 454 110
(2).
[0007] WO 00/46325 (3) recommends hydraulic fluids which comprise a
combination of 1H-1,2,3-benzotriazole or derivatives thereof, such
as 1H-1,2,3-tolutriazole, and 1H-1,2,4-triazole or derivatives
thereof in a weight ratio of from 1:4 to 4:1 as corrosion inhibitor
system. For comparative purposes, Tables 1 to 4 in (3) also
indicate hydraulic fluids which comprise 1H-1,2,4-triazole alone in
concentrations of 0.15% by weight; however, its
corrosion-inhibiting action is acceptable only in the case of
copper.
[0008] The hydraulic fluids and brake fluids for motor vehicles
which are known in the prior art are, however, still unsatisfactory
with respect to their properties and in particular their corrosion
protection. It was therefore an object of the present invention to
provide hydraulic fluids which, in particular, satisfy the
abovementioned requirements for improved corrosion protection in
the case of metals and nonferrous metals.
[0009] We have found that this object is achieved by the hydraulic
or power-transmission fluids defined at the outset.
[0010] The hydraulic fluids, in particular motor vehicle brake
fluids, according to the invention preferably comprise from 0.005
to 0.10% by weight, preferably from 0.005 to 0.08% by weight, in
particular from 0.005 to 0.06% by weight, of component (a).
[0011] In a preferred embodiment, the hydraulic fluids, in
particular motor vehicle brake fluids, according to the invention
comprise component (a) as the only triazole-based corrosion
inhibitor. This is intended to mean that triazoles, such as
1H-1,2,3-benzotriazole, 1H-1,2,3-tolutriazole or hydrogenated
1H-1,2,3-tolutriazole, are excluded here, but inorganic and/or
organic corrosion inhibitors having a different structure may be
present.
[0012] In another preferred embodiment, the hydraulic fluids, in
particular motor vehicle brake fluids, according to the invention
also comprise up to 10% by weight, in particular up to 5% by
weight, of one or more further corrosion inhibitors (b), where, in
the case of the concomitant use of 1H-1,2,3-benzotriazole and/or
1H-1,2,3-tolutriazole and/or derivatives thereof, the weight ratio
between 1H-1,2,4-triazole and said 1H-1,2,3-triazoles must be
greater than 4:1.
[0013] Suitable further corrosion inhibitors (b) here are, in
particular, alkali metal salts of phosphoric acid and phosphorous
acid, fatty acids, such as caprylic, lauric, palmitic, stearic or
oleic acid and alkali metal salts thereof, esters of phosphoric
acid and phosphorous acid, such as ethyl phosphate, dimethyl
phosphate, isopropyl phosphate, diisopropyl phosphate, butyl
phosphite or dimethyl phosphite, substituted or unsubstituted
ethoxylated mono- and dialkylamines and salts thereof with mineral
acids and fatty acids, for example butylamine, hexylamine,
octylamine, isononylamine, oleylamine, dipropylamine,
diisopropylamine or dibutylamine, substituted or unsubstituted
ethoxylated alkanolamines, for example mono-, di- or
triethanolamine, N,N'-di-n-butylaminoethanol or
1,1'-iminodipropan-2-ol, cyclohexylamine, benzimidazole and
hydrogenated tolutriazole, and nitroaromatic compounds, for example
3-nitrobenzaldehyde.
[0014] Said corrosion inhibitors (b) are preferably present in the
hydraulic fluids, in particular motor vehicle brake fluids,
according to the invention in amounts of from 0.001 to 10% by
weight, in particular from 0.001 to 5% by weight.
[0015] In a particularly preferred embodiment, the hydraulic
fluids, in particular motor vehicle brake fluids, according to the
invention comprise, besides 1H-1,2,4-triazole (a), from 0.001 to 5%
by weight, in particular from 0.001 to 0.5% by weight, of one or
more compounds from the group consisting of benzimidazole,
hydrogenated 1H-1,2,3-tolutriazole, purine, adenine,
6-chloropurine, 2,6-dichloropurine, 6-methoxypurine,
1H-1,2,3-triazolo(4,5-b)pyridine, 6-histaminopurine and
6-furfurylaminopurine and, if desired, further corrosion inhibitors
other than (a) as additional corrosion inhibitors (b). Said purine
derivatives are described in German Patent Application P 100 26
010.1 as non-ferrous metal corrosion inhibitors for hydraulic
fluids or brake fluids.
[0016] All the percent by weight data given above and below in each
case relate to the total amount of the hydraulic fluid or brake
fluid, unless stated otherwise. The sum of all components listed
above and below for the hydraulic fluids or brake fluids according
to the invention in each case adds up to 100% by weight.
[0017] The present invention relates, in particular, to brake
fluids for motor vehicles which comprise, as corrosion inhibitors,
said components (a) and, if desired, (b).
[0018] In a preferred embodiment, the motor vehicle brake fluids
according to the invention furthermore comprise, in addition to
components (a) and, if desired, (b), from 0.1 to 97% by weight, in
particular from 30 to 97% by weight, especially from 50 to 97% by
weight, of one or more polyglycol ethers and/or borates
thereof.
[0019] Suitable polyglycol ethers here are, in particular, ethylene
glycol monoalkyl ethers having up to 6 ethylene oxide units and
having up to 4 carbon atoms in the alkyl radical, for example
diethylene glycol monomethyl ether, triethylene glycol monomethyl
ether, triethylene glycol monobutyl ether or tetraethylene glycol
monomethyl ether. Also suitable are ethylene glycol dialkyl ethers
and propylene glycol dialkyl ethers having up to 6 alkylene oxide
units and having up to 4 carbon atoms in each of the alkyl
radicals, for example triethylene glycol dimethyl ether,
tetraethylene glycol dimethyl ether, diethylene glycol
di-tert-butyl ether, diethylene glycol dibutyl ether, diethylene
glycol di-tert-butyl ether or dipropylene glycol dimethyl
ether.
[0020] Suitable boric acid esters of said or other polyglycol
ethers are described, in particular, in the specifications EP-B 013
925 (cyclic bisboric acid esters), DE-C 28 04 535
(nitrogen-containing boric acid esters), DE-A 24 38 038 (boric acid
alkylene glycol monoalkyl ether esters) and DE-B 17 68 933 (boric
acid trisalkoxyalkyl esters).
[0021] Instead of said polyglycol ethers and/or boric acid esters
thereof, the motor vehicle brake fluids according to the invention
may also comprise, as principal component, those based on
carboxylic acid esters, mineral oils or silicone oils.
[0022] In a further preferred embodiment, the motor vehicle brake
fluids according to the invention furthermore comprise, besides
components (a) and, if desired, (b), from 0.1 to 50% by weight, in
particular from 1 to 40% by weight, especially from 5 to 30% by
weight, of one or more polyglycols.
[0023] Suitable polyglycols here are, in particular, relatively
high-boiling products of the reaction of ethylene oxide and/or
propylene oxide and/or butylene oxide with water or diols, in
particular corresponding products of the mixtures of ethylene oxide
and propylene oxide with water. The number of alkylene oxide units
in polyglycols of this type is normally from 2 to 10.
[0024] The action of these high-boiling polyglycols is that of a
lubricant, which is attributable essentially to an improvement in
the temperature/viscosity behavior. The polyglycols give the
low-viscosity polyglycol ethers sufficient viscosity at high
temperatures and thus ensure adequate lubrication. Adequate
lubrication is necessary in the components of the motor vehicle
braking system since rubber or elastomers have to slide on metal
with very low wear in these systems.
[0025] Further components and assistants in the motor vehicle brake
fluids according to the invention can be conventional antioxidants,
for example phenothiazine and/or those based on phenol, and
conventional antifoams.
[0026] In addition, the brake fluids according to the invention may
comprise the cyclic carboxylic acid derivatives mentioned in WO
00/65001, which are suitable as components for reducing the
low-temperature viscosity in the presence of water.
[0027] The presence of said small amount of 1H-1,2,4-triazole
ensures, in an excellent manner, that the hydraulic fluids or motor
vehicle brake fluids according to the invention meet the
requirements mentioned at the outset and that, in particular, a
corrosion behavior which is generally good compared with the prior
art, i.e. improved corrosion protection in the case of metals, such
as iron, steel, tinplate, cast iron (gray iron), lead, tin,
chromium, zinc, aluminum, magnesium and alloys thereof, and in the
case of solder metals, for example solder tin, and in the case of
non-ferrous metals, such as copper and alloys thereof, for example
brass, is effected.
[0028] Further advantages of the hydraulic fluids or motor vehicle
brake fluids according to the invention are their favorable
low-temperature viscosity, good water compatibility, a mild pH,
good low-temperature, high-temperature and oxidation stability and
good chemical stability, a favorable behavior (i.e. good
compatibility) with materials such as rubbers, plastics, glue
lines, fiber, elastomer and rubber seals and similar materials, as
well as good lubricating behavior.
[0029] Not least, the use of only a small amount of
1H-1,2,4-triazole in the hydraulic fluids or motor vehicle brake
fluids according to the invention is advantageous both in economic
and in ecological terms.
[0030] The examples below are intended to explain the present
invention without representing a restriction.
APPLICATIONAL EXAMPLES
[0031] Based on the commercially available DOT 4 or DOT 5.1 brake
fluids BF 1 (ERBP: 267.degree. C., wet ERBP: 173.degree. C.,
kinematic viscosity at -40.degree. C.: 676 cSt) and BF 2 (ERBP:
263.degree. C., wet ERBP: 181.degree. C., kinematic viscosity at
-40.degree. C.: 850 cSt) each with 0.05% by weight of
1H-1,2,3-tolutriazole as non-ferrous metal corrosion inhibitor, the
brake fluids BF 1a, BF 1b, BF 1c and BF 2a according to the
invention were tested in comparison thereto.
[0032] The motor vehicle brake fluids used had the following
compositions:
[0033] BF 1:
[0034] 55.00% by weight of triethylene glycol methyl ether
borate,
[0035] 43.44% by weight of a mixture of triethylene glycol
monomethyl ether, tetraethylene glycol monomethyl ether,
triethylene glycol monobutyl ether and diethylene glycol monomethyl
ether,
[0036] 1.51% by weight of a mixture of 1,1'-iminodipropan-2-ol,
phenothiazine and a phosphoric acid ester
[0037] 0.05% by weight of 1H-1,2,3-tolutriazole
[0038] BF 2:
[0039] 68.00% by weight of triethylene glycol methyl ether
borate,
[0040] 28.84% by weight of a mixture of triethylene glycol
monomethyl ether, diethylene glycol monomethyl ether, diethylene
glycol monobutyl ether and diethylene glycol,
[0041] 3.11% by weight of a mixture of 1,1'-iminodipropan-2-ol,
phenothiazine and a phosphonic acid derivative
[0042] 0.05% by weight of 1H-1,2,3-tolutriazole.
[0043] Brake fluids BF 1a and BF 2a according to the invention
differ from BF 1 and BF 2 only in that the 0.05% by weight of
1H-1,2,3-tolutriazole has been replaced by the same amount of
1H-1,2,4-triazole; brake fluid BF 1b comprises 0.04% by weight of
1H-1,2,4-triazole and 0.01% by weight of adenine instead of 0.05%
by weight of 1H-1,2,3-tolutriazole; brake fluid BF 1c according to
the invention comprises 0.07% by weight of 1H-1,2,4-triazole (but
only 54.98% by weight of triethylene glycol monomethyl ether
borate) instead of 0.05% by weight of 1H-1,2,3-tolutriazole.
[0044] The applicational studies were carried out in accordance
with the PSA Peugeot-Citron D 53 5387 copper corrosion test in the
2000 version. In this test, firstly a copper sheet which has
previously been cleaned in acetone, with a total surface area of
1000 cm.sup.2 (dimensions: 71.4 cm.times.7 cm.times.0.05 cm) is
coiled up in the form of a round cylinder in such a way that the
metal surface in the interior is not in contact with itself. The
copper sheet is placed in a mixture of 294 ml of brake fluid
containing 6 ml of distilled water and heated at 100.degree. C. for
100 hours; 10 liters per hour of air which had previously been
passed through distilled water cooled to 2.degree. C. are passed
through the fluid. After the test, the appearance of the unrolled
copper sheet and the appearance of the fluid are assessed visually,
and the copper content of the fluid is determined.
[0045] The results from the test described are shown in Table 1
below.
1TABLE 1 Cu content Cu sheet, [mg/kg] appearance Fluid, appearance
pH BF 1 24 Thick coating Cloudy, 7.4 (Comp.): precipitations BF 1a:
29 Bright, no Amber-colored, 7.6 coating clear BF 1b: 34 Bright, no
Amber-colored, 7.6 coating clear BF 1c: 18 Bright, no
Amber-colored, 7.5 coating clear BF 2 10 Thick coating Cloudy, 7.6
(Comp.): precipitations BF 2a: 30 Bright, no Amber-colored, 7.7
coating clear
[0046] It can be seen that the formulations according to the
invention, in contrast to conventional brake fluids, such as BF 1
and BF 2, not only offer very good copper corrosion protection with
a low Cu content in the test fluid, but in addition also produce a
coating-free metal surface and no sediment formation in the brake
fluid.
[0047] The results shown below for the corrosion test in accordance
with SAE J 1704 (January 1997) also confirm that brake fluids
according to the invention, such as BF 2a, having a low
1H-1,2,4-triazole content offer advantages over formulations not in
accordance with the invention, such as BF 1d, having a high
1H-1,2,4-triazole content, since they exhibit a better corrosion
result in the case of copper (BF 1d corresponded to BF 1, but
comprised 0.20% by weight of 1H-1,2,4-triazole instead of
1H-1,2,3-tolutriazole and comprised only 54.85% by weight of
triethylene glycol monomethyl ether borate):
[0048] The results from the corrosion test in accordance with SAE J
1704 (January 97) are shown in Table 2 below.
2TABLE 2 BF 2a BF 1d (comparison) Metal Weight change [mg/cm.sup.2]
Weight change [mg/cm.sup.2] Tinplate 0.00 -0.01 Steel +0.03 0.00
Aluminum 0.00 0.00 Cast iron +0.05 +0.02 Brass 0.00 0.00 Copper
-0.05 -0.11 Zinc +0.05 +0.04
* * * * *