WO2002081604A1

WO2002081604A1 - Hydraulic fluids with improved anti-corrosion properties

Info

Publication number: WO2002081604A1
Application number: PCT/EP2002/003671
Authority: WO
Inventors: Bernd Wenderoth; Michael Roida; Bayram Aydin; Uwe Fidorra
Original assignee: Basf Aktiengesellschaft
Priority date: 2001-04-09
Filing date: 2002-04-03
Publication date: 2002-10-17
Also published as: AR033453A1; PL197796B1; EP1379615A1; BR0208415A; DE10117647A1; EP1379615B1; CN1501971A; ZA200308690B; CN1312261C; PL367159A1; PT1379615E; SK286828B6; NO325635B1; CZ20032736A3; MXPA03007944A; NO20034495D0; SK11922003A3; CA2442697A1; ES2235077T3; CA2442697C

Abstract

The invention relates to hydraulic fluids, in particular brake fluids for motor vehicles, with improved anti-corrosion properties, containing (a) between 0.005 and 0.125 wt. % 1H-1,2,4-triazole and (b) between 0 and 10 wt. % of one or more corrosion inhibitors, whereby with the co-use of 1H-1,2,3-benzotriazole and/or 1H-1,2,3-tolyltriazole and/or their derivatives, the weight ratio of 1H-1,2,4-triazole to the aforementioned 1H-1,2,3-triazoles must be greater than 4:1.

Description

Hydraulic fluids with improved corrosion protection

description

The present invention relates to hydraulic fluids, in particular brake fluids for motor vehicles, with improved corrosion protection, which

(a) 0.005 to 0.125 wt% 1H-1, 2,4-triazole and

(b) 0 to 10% by weight of one or more further corrosion inhibitors, where the weight of 1H-1,2, 3-benzotriazole and / or 1H-1, 2, 3-tolutriazole and / or their derivatives is also used Ratio of 1H-1, 2,4-triazole to said 1H-1,2, 3-triazoles must be greater than 4: 1,

contain.

Hydraulic fluids and especially brake fluids for motor vehicles are subject to very high requirements with regard to their chemical and physical properties. According to the existing standards and specifications for brake fluids from the US Department of Transportation in the Federal Motor Vehicle Safety Standard FMVSS-No. 115 and the SEJ 1704 standard published by the Society of Automotive Engineers, modern brake fluids are said to have high dry boiling points (reflux boiling points, dry [ERBP "]) and high wet boiling points (reflux boiling points, moist [" wet ERBP "]) , but on the other hand also have a viscosity that changes only slightly within a wide temperature range.

In addition, there are further requirements from the automotive industry for improved corrosion protection for metals and non-ferrous metals. Corrosion inhibitors in brake fluids have the task of preventing the destruction of metallic materials caused by corrosion.

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 long been known, for example from EP-A 028 789 (1) and EP-A 454 110 (2).

In WO 00/46325 (3) hydraulic fluids are recommended which contain a combination of 1H-1,2, 3-benzotriazole or its derivatives such as 1H-1,2, 3-tolutriazuol and 1H-1, 2,4-triazole or whose Derivatives in a weight ratio of 1: 4 to 4: 1 contained as a corrosion inhibitor system. For comparison purposes, hydraulic fluids are also given in Tables 1 to 4 of (3), which contain 1H-1,2,4-triazole alone in concentrations of 0.15% by weight; however, their corrosion-preventing effect is only acceptable for copper.

The hydraulic fluids and brake fluids for motor vehicles known in the prior art are, however, in need of improvement with regard to their properties and in particular corrosion protection. The object was therefore to provide hydraulic liquids which, in particular, meet the above-mentioned requirements for improved corrosion protection in metals and non-ferrous metals.

Accordingly, the hydraulic or power transmission fluids defined at the outset were found.

The hydraulic fluids according to the invention, in particular brake fluids for motor vehicles, preferably contain 0.005 to 0.10% by weight, preferably 0.005 to 0.08% by weight, in particular 0.005 to 0.06% by weight, of component (a) ,

In a preferred embodiment, the hydraulic fluids according to the invention, in particular brake fluids for motor vehicles, contain component (a) as the sole corrosion inhibitor based on triazole. This means that triazoles such as 1H-1, 2,3-benzotriazole, 1H-1,2, 3-tolutriazole or hydrogenated 1H-1, 2,3-tolutriazole are excluded here, inorganic and / or organic corrosion inhibitors of a different structure can however be present.

In another preferred embodiment include hydraulic fluids according to the invention, in particular motor vehicle brake, even up to 10 wt .-%, in particular up to 5 wt .-% of one or more further Korro ^¬ sion inhibitors (b), wherein in the concomitant use of 1H -1, 2, 3-benzotriazole and / or 1H-1, 2, 3-tolutriazole and / or their derivatives the weight ratio of 1H-1, 2, 4-triazole to the mentioned 1H-1,2 , 3-triazoles must be greater than 4: 1.

As further corrosion inhibitors (b) there are especially alkali metal salts of phosphoric acid and phosphorous acid, fatty acids such as caprylic, auric, palitinic, stearic or oleic acid and their alkali metal salts, esters of phosphoric acid and phosphorous acid such as 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, for example butylamine, hexylamine, octylamine, isononylamine, oleylamine, dipropylamine, diisopropylamine or dibutylamine, optionally 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 nitroaromatics, for example 3-nitrobenzaldehyde, into consideration.

The corrosion inhibitors (b) mentioned are preferably present in amounts of 0.001 to 10% by weight, in particular 0.001 to 5% by weight, in the hydraulic fluids according to the invention, in particular brake fluids for motor vehicles.

In a particularly preferred embodiment, the hydraulic fluids according to the invention, in particular brake fluids for motor vehicles, contain 0.001 to 5% by weight, in particular 0.001 to 0.5% by weight, in addition to 1H-1, 2, 4-triazole (a) as additional corrosion inhibitors (b) .-%, one or more compounds from the group benzimidazole, hydrogenated 1H-1, 2, 3-tolutriazole, purine, adenine, 6-chloropurine, 2, 6-dichloropurine, 6-methoxypurine, 1H-1, 2, 3-triazolo (4, 5B) pyridine, 6-histaminopurine and 6-furfurylaminopurine and optionally other corrosion inhibitors other than (a). The purine derivatives mentioned are described as non-ferrous metal corrosion inhibitors for hydraulic fluids or brake fluids in German patent application Az. P 100 26 010.1.

All of the above and following parts by weight relate to the total amount of hydraulic fluid or brake fluid, unless otherwise stated. The sum of all the components listed above and below for the hydraulic fluids or brake fluids according to the invention adds up to 100% by weight.

The present invention relates in particular to brake fluids for motor vehicles which contain the components (a) and optionally (b) mentioned as corrosion inhibitors.

In a preferred embodiment, the brake fluids for motor vehicles according to the invention contain, in addition to components (a) and optionally (b), 0.1 to 97% by weight, in particular 30 to 97% by weight, especially 50 to 97% by weight , one or more polyglycol ethers and / or their boric acid esters. Suitable polyglycol ethers are above all ethylene glycol monoalkyl ethers with up to 6 ethylene oxide units and with up to 4 carbon atoms in the alkyl radical, such as, for example, methyldiglycol, methyltriglycol, butyltriglycol or methyltetraglycol. Also suitable are ethylene glycol or propylene glycol dialkyl ethers with up to 6 alkylene oxide units and each with up to 4 carbon atoms in the alkyl radicals, such as, for example, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol di-tert.- butyl ether, diethylene glycol dibutyl ether, butyl diglycol tert-butyl ether or dipropylene glycol dimethyl ether.

Suitable boric acid esters of said polyglycol ethers or of other polyglycol ethers are described in particular in documents EP-B 013 925 (cyclic bis-boric 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 (tris-alkoxyalkyl borate).

Instead of the polyglycol ethers mentioned and / or their boric acid esters, the brake fluids according to the invention for motor vehicles can also contain, as the main component, those based on carboxylic acid esters, mineral oils or silicone oils.

In a further preferred embodiment, the brake fluids for motor vehicles according to the invention contain, in addition to components (a) and optionally (b), 0.1 to 50% by weight, in particular 1 to 40% by weight, especially 5 to 30% by weight. %, one or more polyglycols.

Suitable polyglycols are, above all, higher-boiling reaction products of ethylene oxide and / or propylene oxide and / or butylene oxide with water or diols; in particular, corresponding reaction products of mixtures of ethylene oxide and propylene oxide with water are used. The number of alkylene oxide units in such polyglycols is usually 2 to 10.

The effect of these high-boiling polyglycols is that of a lubricant, which is essentially due to an improvement in the temperature-viscosity behavior. The polyglycols give the thin-bodied polyglycols sufficient viscosity at high temperatures and thus ensure adequate lubrication. Sufficient lubrication is therefore necessary in the components of the motor vehicle brake system, since rubber or elastomers on metal have to slide as wear-free as possible. Further components and auxiliaries in the brake fluids for motor vehicles according to the invention can be customary antioxidants, such as phenothiazine and / or those based on phenol, and customary defoamers.

In addition, the brake fluids according to the invention can contain the cyclic carboxylic acid derivatives listed in WO 00/65001, which are suitable as components for lowering the low-temperature viscosity in the presence of water.

The presence of the small amount of 1H-1, 2, 4-triazole mentioned ensures in an excellent manner that the hydraulic fluids or brake fluids for motor vehicles according to the invention meet the requirements mentioned at the outset and that, in particular, a generally good corrosion behavior compared to the prior art , ie improved corrosion protection for metals such as iron, steel, tinplate, cast iron (gray cast iron), lead, tin, chromium, zinc, aluminum, magnesium and their alloys and for soldering metals, for example solder, and for non-ferrous metals such as copper and their alloys, for example Brass.

Further advantages of the hydraulic fluids or brake fluids for motor vehicles according to the invention are their favorable low-temperature viscosity, good water compatibility, a gentle pH value, good low-temperature, high-temperature and oxidation stability as well as good chemical stability, favorable behavior (ie good behavior) Compatibility) with materials such as rubbers, plastics, glue joints, fiber, elastomer and rubber seals and similar materials as well as good lubrication behavior.

Last but not least, the use of only a small amount of 1H-1,2,4-triazole in the hydraulic fluids or brake fluids according to the invention for motor vehicles is both economically and ecologically advantageous.

The following examples are intended to illustrate the present invention without restricting it.

Application engineering examples

Based on the standard DOT 4 or DOT 5.1 brake fluids BF 1 (ERBP: 267 ° C, wet ERBP: 173 ° C, kinematic viscosity at -40 ° C: 676 cSt) and BF 2 (ERBP: 263 ° C, wet ERBP: 181 ° C, kinematic viscosity at -40 ° C: 850 cSt) with 0.05 wt .-% lH-l, 2,3-tolutriazole as a non-ferrous metal corrosion inhibitor In comparison, the brake fluids BF la, BF lb, BF lc and BF 2a tested according to the invention.

The motor vehicle brake fluids used had the following compositions:

BF 1:

55.00% by weight of methyltriglycol-borate, 43.44% by weight of a mixture of methyltriglycol, methyltetraglycol, butyltriglycol and methyldiglycol, 1.51% by weight of a mixture of 1,1'-iminodipropan-2-ol, Phenothiazine and a phosphoric acid ester 0.05 wt .-% lH-l, 2,3-tolutriazole

BF 2:

68.00% by weight of methyl triglycol borate,

28.84% by weight mixture of methyl triglycol, methyl diglycol, butyl diglycol and diglycol,

3.11% by weight mixture of 1, l'-iminodipropan-2-ol, hydroxyanisole and a phosphonic acid derivative 0.05% by weight lH-l, 2,3-tolutriazole.

The brake fluids BF la and BF 2a according to the invention differ from BF 1 and BF 2 only in that instead of 0.05% by weight 1H-l, 2,3-tolutriazole they contain the same amount of 1H-1, 2,4 -Triazole contained; the brake fluid BF 1b according to the invention contained 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; The brake fluid BF 1c according to the invention contained 0.07% by weight of 1H-1, 2, 4-triazole instead of 0.05% by weight of 1H-l, 2,3-tolutriazole (but only 54.98% by weight for this) % Methyl triglycol borate).

The application tests were carried out in accordance with the copper corrosion test PSA D 53 5387 in the version of the year 2000 from the company PSA Peugeot-Citroen. First, a copper sheet with a total area of 1000 cm2 (dimensions: 71.4 cm x 7 cm x 0.05 cm) previously cleaned in acetone is rolled up in a spiral shape in the form of a round cylinder so that the metal surface inside does not touch. The copper sheet is placed in a mixture of 294 ml of brake fluid with 6 ml of distilled water and heated to 100 ° C. for 100 hours; 10 liters of air are passed through the liquid per hour, which was previously passed through distilled water cooled to 2 ° C. After the test, the appearance of the re-rolled copper sheet and optically assessed the appearance of the liquid and determined the copper content of the liquid.

The results after the test described are shown in Table 1 below.

Table 1:

It can be seen that, in contrast to conventional brake fluids such as BF 1 and BF 2, the formulations according to the invention not only offer very good copper corrosion protection with a low Cu content in the test fluid, but also additionally cause a deposit-free metal surface and no sediment formation in the brake fluid.

The results listed below in the corrosion test according to SAE J 1704 (Jan. 97) also prove that brake ^fluids according to the invention such as BF 2a with a low 1H-1, 2, 4-triazole content compared to formulations according to the invention such as BF ld triazole-2,4-content offer advantages with a high lH-l, as they reach a better copper corrosion result show (BF ld ent ^¬ said BF 1, containing instead of 1H-1, 2, 3-tolutriazole However 0, 20% by weight lH-l, 2,4-triazole and only 54.85% by weight methyltriglycol-borate):

The results after the corrosion test according to SAE J 1704 (Jan. 97) are shown in Table 2 below. Table 2:

Claims

claims

1. Containing hydraulic fluids with improved corrosion protection

(a) 0.005 to 0.125 wt% 1H-1,2,4-triazole and

(b) 0 to 10% by weight of one or more further corrosion inhibitors, with the use of 1H-1, 2, 3-benzotriazole and / or 1H-1, 2, 3-tolutriazole and / or their derivatives the weight ratio of 1H-1, 2, 4-triazole to said 1H-1, 2, 3-triazoles must be greater than 4: 1.

2. Hydraulic liquids according to claim 1, containing 0.005 to 0.08% by weight of component (a).

3. Hydraulic liquids according to claim 1 or 2, containing component (a) as the sole corrosion inhibitor based on triazole.

4. Hydraulic liquids according to claim 1 or 2, containing as component (b) 0.001 to 0.5% by weight of one or more compounds from the group benzimidazole, hydrogenated 1H-1, 2, 3-tolutriazole, purine, adenine, 6- Chloropurine, 2,6-dichloropurine, 6-methoxypurine, 1H-1, 2, 3-triazolo (4, 5B) pyryidine, 6-His aminopurine * and 6-furfurylaminopurine and optionally other corrosion inhibitors different from (a).

5. Brake fluids for motor vehicles, containing components (a) and optionally (b) according to claims 1 to 4 as corrosion inhibitors.

6. Brake fluids for motor vehicles according to claim 5, containing in addition to components (a) and optionally (b), further 0.1 to 97% by weight of one or more polyglycol ethers and / or their boric acid esters.

7. Brake fluids for motor vehicles according to claim 5 or 6, containing in addition to components (a) and optionally (b) further 0.1 to 50 wt .-% of one or more polyglycols.