DE10117647A1 - Hydraulic fluids with improved corrosion protection - Google Patents

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

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

contain.

Hydraulic fluids and especially brake fluids for motor vehicles are subject to their chemical and physical properties very high requirements. Ent speaking of the existing norms and specifications for brakes liquids from the U.S. Department of Transportation in Federal Mo tor Vehicle Safety Standard FMVSS no. 116 and that of the Society of Automotive Engineers published standard SAE J 1704 modern brake fluids on the one hand have high dry boiling points (Reflux boiling points, dry [Equilibrium reflux boiling point, "ERBP"]) and high wet boiling points (reflux boiling points, moist ["wet ERBP"]), but also a viscosity have, which are within a wide temperature range little changes.

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

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 Liquids or brake fluids have 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 is a combination of 1H-1,2,3-benzotriazole or its deri such as 1H-1,2,3-tolutriazuol and 1H-1,2,4-triazole or its  Derivatives in a weight ratio of 1: 4 to 4: 1 as corrosion inhibitors bitor system included. For comparison purposes, Table 1 to 4 of (3) also specified hydraulic fluids that 1H-1,2,4-triazole alone in concentrations of 0.15% by weight hold; However, their corrosion-preventing effect is only at Copper acceptable.

The hydraulic fluids known in the prior art and brake fluids for automobiles are in view their properties and in particular depending on the corrosion protection but still in need of improvement. It was therefore the task to provide hydraulic fluids, which in particular the above requirements for an improved Corrosion protection for metals and non-ferrous metals.

Accordingly, the hydraulic or power transmission fluids 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, ins particularly 0.005 to 0.06% by weight of component (a).

The hydraulic fluids according to the invention, in particular Brake fluids for motor vehicles contained in a before preferred embodiment, component (a) as the sole corro ion 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 can be excluded here, inorganic and / or organic corrosion inhibitors of other structures can however be present.

In another preferred embodiment, the hydraulic fluids according to the invention, in particular Brake fluids for motor vehicles, up to 10% by weight, in particular up to 5% by weight of one or more further corro sionsinhibitoren (b), with the use of 1H-1,2,3-benzo triazole and / or 1H-1,2,3-tolutriazole and / or their derivatives the weight ratio of 1H-1,2,4-triazole to the above 1H-1,2,3-triazoles must be greater than 4: 1.

Above all, there are other corrosion inhibitors (b) Alkali metal salts of phosphoric acid and phosphorous acid, fat acids such as caprylic, lauric, palmitic, stearic or oleic acid such as their alkali metal salts, esters of phosphoric acid and the phosphorous acid such as ethyl phosphate, dimethyl phosphate, isopro pyl phosphate, diisopropyl phosphate, butyl phosphite or dimethyl phosphite,  optionally ethoxylated mono- and dialkylamines and whose salts with mineral and fatty acids, e.g. B. butylamine, hexyl amine, octylamine, isononylamine, oleylamine, dipropylamine, diiso propylamine or dibutylamine, optionally ethoxylated alkanol amines, e.g. B. mono-, di- or triethanolamine, N, N'-di-n-butylami noethanol or 1,1'-iminodipropan-2-ol, cyclohexylamine, benz imidazole and hydrogenated tolutriazole and nitroaromatics, e.g. B. 3-nitrobenzaldehyde.

The corrosion inhibitors (b) mentioned are preferably 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, ins special brake fluids for motor vehicles.

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

All of the above and following% by weight data relate to the total amount of hydraulic fluid or the brake fluid unless otherwise stated. The Sum of all components listed above and below for the hydraulic fluids or brakes according to the invention liquids add up to 100% by weight.

The present invention relates in particular to brakes Automotive fluids used as corrosion inhibitors contain said components (a) and optionally (b).

The brake fluids for motor vehicles according to the invention ent hold next to the components in a preferred embodiment (a) and optionally (b) further 0.1 to 97 wt .-%, ins particularly 30 to 97% by weight, especially 50 to 97% by weight, of one or several polyglycol ethers and / or their boric acid esters.  

Suitable polyglycol ethers are especially ethylene glycol mo noalkyl ether with up to 6 ethylene oxide units and with up to 4 Carbon atoms in the alkyl radical, such as methyl diglycol, Methyl triglycol, butyl triglycol or methyl tetraglycol. Farther come with up to ethylene glycol or propylene glycol dialkyl ether 6 alkylene oxide units and each with up to 4 carbon atoms in the alkyl radicals, such as Triethy lenglycol dimethyl ether, tetraethylene glycol dimethyl ether, the ethylene glycol di-tert-butyl ether, diethylene glycol dibutyl ether, Butyl diglycol tert-butyl ether or dipropylene glycol dimethyl ther.

Suitable boric acid esters of said or other polyglyko Ethers are particularly described in the documents EP-B 013 925 (cycli Sche bis-boric acid ester), DE-C 28 04 535 (nitrogen-containing boron acid esters), DE-A 24 38 038 (boric acid-alkylene glycol monoalkyls ther esters) and DE-B 17 68 933 (tris-alkoxyalkyl borate) described.

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

The brake fluids for motor vehicles according to the invention ent hold in a further preferred embodiment in addition to the Components (a) and optionally (b) further 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 conversion tion products of ethylene oxide and / or propylene oxide and / or Butylene oxide with water or diols, in particular, find ent Talking reaction products of mixtures of ethylene oxide and Propylene oxide with water use. The number of alkylene oxide Units in such polyglycols are usually 2 to 10.

The effect of these high-boiling polyglycols is one Lubricant, which essentially indicates an improvement in the Temperature-viscosity behavior is attributable. The poly Glycols give the thin polyglycol ethers at high Temperatures enough viscosity and thus ensure a adequate lubrication. Sufficient lubrication is therefore in the components of the motor vehicle brake system necessary because there Glide rubber or elastomers on metal as wear-free as possible have to.  

Other components and auxiliaries in the invention Brake fluids for motor vehicles can be common anti oxidizing agents such as B. phenothiazine and / or such Phenol base, and usual defoamers.

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

The presence of said small amount of 1H-1,2,4-triazole ensures in an excellent manner that the invention hydraulic fluids or brake fluids for power vehicles meet the requirements mentioned at the beginning and that in particular a generally good compared to the prior art t corrosion behavior, d. H. improved corrosion protection for metals such as iron, steel, tinplate, cast iron (gray cast iron), Lead, tin, chrome, zinc, aluminum, magnesium and their alloys gene and with solder metals, for example solder, as well as with colored metals such as copper and their alloys, for example mes sing, is effected.

Further advantages of the hydraulic fluid according to the invention Brake fluids for motor vehicles are their gün constant low temperature viscosity, good water compatibility, a gentle pH value, a good cold, high temperature and Oxidation stability as well as good chemical stability, a favorable behavior (i.e. good tolerance) towards Materials such as rubbers, plastics, glue joints, fiber, Elastomer and rubber seals and similar materials as well good lubrication behavior.

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

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

Application engineering examples

Based on the commercially available DOT 4 or DOT 5.1 brake fluid 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, kine Matic viscosity at -40 ° C: 850 cSt) with 0.05% by weight each 1H-1,2,3-tolutriazole as a non-ferrous metal corrosion inhibitor was used in  Comparison with the brake fluids BF 1a, BF according to the invention 1b, BF 1c and BF 2a checked.

The motor vehicle brake fluids used had the following compositions:

BF 1:
55.00% by weight of methyl triglycol borate,
43.44% by weight mixture of methyltriglycol, methyltetraglycol, butyltriglycol and methyldiglycol,
1.51% by weight mixture of 1,1'-iminodipropan-2-ol, phenothiazine and a phosphoric acid ester
0.05 wt% 1H-1,2,3-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 1,1'-iminodipropan-2-ol, hydroxyanisole and a phosphonic acid derivative
0.05% by weight of 1H-1,2,3-tolutriazole.

The brake fluids BF 1a and BF 2a under differed from BF 1 and BF 2 only in that they instead of 0.05% by weight of 1H-1,2,3-tolutriazole the same amount 1H-1,2 contained 4-triazole; the brake fluid according to the invention speed BF 1b contained 1H-1,2,3-tolutriazole instead of 0.05% by weight 0.04% by weight of 1H-1,2,4-triazole and 0.01% by weight of adenine; the Brake fluid BF 1c according to the invention contained instead of 0.05 wt% 1H-1,2,3-tolutriazole 0.07 wt% 1H-1,2,4-triazole (but only 54.98% by weight of 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 by PSA Peugeot-Citroën. Here, a copper sheet previously cleaned in acetone with a total area of 1000 cm ² (dimensions: 71.4 cm × 7 cm × 0.05 cm) 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 at 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 the appearance of the liquid are assessed optically and the copper content of the liquid is determined.

The results after the test described are as follows Table 1.

Table 1

It can be seen that the formulations according to the invention in Contrary to conventional brake fluids like BF 1 and BF 2 not just very good copper corrosion protection with little Offer Cu content in the test liquid, but also additionally a deposit-free metal surface and no sediment formation in the Cause brake fluid.

The results listed below in the corrosion test according to SAE J 1704 (Jan. 97) also demonstrate that inventive brakes liquids like BF 2a with a low 1H-1,2,4-triazole Ge compared to formulations not according to the invention such as BF 1d with a high 1H-1,2,4-triazole content offer advantages because they show a better corrosion result with copper (BF 1d ent spoke BF 1, but contained 1H-1,2,3-tolutriazole instead 0.20% by weight of 1H-1,2,4-triazole and only 54.85% by weight of methyl trigly kol-borate):

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

Table 2

Claims (7)

1. Containing hydraulic fluids with improved corrosion protection

• a) 0.005 to 0.125% by weight of 1H-1,2,4-triazole and
• b) 0 to 10 wt .-% of one or more further corrosion inhibitors, the weight when using 1H-1,2,3-benzotriazole and / or 1H-1,2,3-tolutriazole and / or their derivatives . Ratio of 1H-1,2,4-triazole to the 1H-1,2,3-triazoles mentioned 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 Triazole-based. 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-dich loropurine, 6-methoxypurine, 1H-1,2,3-triazolo (4,5B) pyryidine, 6-histaminopurine and 6-furfurylaminopurine and optionally other corrosion inhibitors other than (a). 5. Brake fluids for motor vehicles, containing as a corro sion inhibitors components (a) and optionally (b) according to claims 1 to 4. 6. Brake fluids for motor vehicles according to claim 5, ent holding next to components (a) and optionally (b) white thereafter 0.1 to 97 wt .-% 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.