KR20030087063A - Hydraulic fluids with improved anti-corrosion properties - Google Patents

Abstract

The present invention relates to hydraulic hydraulic fluids, in particular automotive braking fluids having improved anticorrosive properties comprising:

(a) 0.005 to 0.125 weight percent of 1H-1,2,4-triazole, and

(b) 0 to 10% by weight of one or more additional corrosion inhibitors (1H-1,2,3-benzotriazole and / or 1H-1,2,3-tolutriazole and / or derivatives thereof) C, the weight ratio between 1H-1,2,4-triazole and 1H-1,2,3-triazole is at least 4: 1.

Description

HYDRAULIC FLUIDS WITH IMPROVED ANTI-CORROSION PROPERTIES}

Hydraulic hydraulic fluids and in particular automotive braking fluids must meet very high chemical and physical requirements. According to the current standards and specifications for braking fluid as issued by the US Department of Transportation as Federal Vehicle Safety Standard FMVSS No. 116 and issued by the Society of Automotive Engineers as standard SAE J 1704, the current braking amount is high. It must have a dry boiling point (reflux boiling point, dry [equilibrium reflux boiling point, "ERBP"]), and also a high wet boiling point (reflux boiling point, wet ["wet ERBP"]), while its viscosity is only slightly over a wide temperature range. This must be changed.

There are also stricter regulations from the automotive industry for improved anticorrosion for metals and nonferrous metals. The corrosion inhibitor in the braking liquid has a role of preventing the destruction of the metal material caused by the 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 Known for some time, for example in EP-A 028 789 (1) and EP-A 454 110 (2).

WO 00/46325 (3) discloses 1H-1,2,3-benzotriazole or derivatives thereof, such as 1H-1,2,3-tolutriazole and 1H-1,2,4 as corrosion inhibitor systems. Hydraulic hydraulic fluids comprising a combination of triazoles or derivatives thereof in a weight ratio of 1: 4 to 4: 1 are recommended. For comparison purposes, Tables 1 to 3 of Document (3) describe hydraulic hydraulic fluids containing 1H-1,2,4-triazole alone at a concentration of 0.15% by weight. Only allowed in cases.

However, hydraulic hydraulic fluids and vehicle braking fluids known in the art of defoaming are still unsatisfactory with regard to their properties, in particular their corrosion resistance. It is therefore an object of the present invention to provide a hydraulic hydraulic fluid which satisfies the above requirements for improved corrosion resistance, in particular in the case of metals and nonferrous metals.

The present invention relates to hydraulic hydraulic fluids, in particular automotive braking fluids having improved anticorrosive properties comprising:

(a) 0.005 to 0.125 weight percent of 1H-1,2,4-triazole, and

(b) 0 to 10% by weight of one or more additional corrosion inhibitors (1H-1,2,3-benzotriazole and / or 1H-1,2,3-tolutriazole and / or derivatives thereof) C, the weight ratio between 1H-1,2,4-triazole and 1H-1,2,3-triazole is at least 4: 1.

The inventors have found that this object is achieved by the hydraulic fluid or power transmission fluid as defined above.

Hydraulic hydraulic fluids, in particular vehicle braking fluids, according to the invention preferably comprise from 0.005 to 0.10% by weight of component (a), preferably from 0.005 to 0.08% by weight, in particular from 0.005 to 0.06% by weight.

In a preferred embodiment, the hydraulic hydraulic fluid, in particular vehicle braking fluid, according to the present invention comprises component (a) solely as a triazole-based corrosion inhibitor. This excludes triazoles such as 1H-1,2,3-benzotriazole, 1H-1,2,3-tolutriazole or hydrogenated 1H-1,2,3-tolutriazole, although different structures It is intended to mean that inorganic and / or organic corrosion inhibitors may be present.

In another preferred embodiment, the hydraulic fluid, in particular the vehicle braking fluid, according to the invention also comprises at least 10% by weight, in particular at most 5% by weight, of at least one further corrosion inhibitor, wherein 1H-1,2,3-benzotria When used in combination with a sol and / or 1H-1,2,3-tolutriazole and / or derivatives thereof, between 1H-1,2,4-triazole and 1H-1,2,3-triazole The weight ratio should be at least 4: 1.

Suitable further corrosion inhibitors (b) are, in particular, alkali metal salts of phosphoric acid and phosphorous acid, fatty acids such as caprylic acid, lauric acid, palmitic acid, stearic acid or oleic acid and their alkali metal salts, phosphoric acid and phosphorous acid, Such as ethyl phosphate, dimethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphate or dimethyl phosphite, substituted or unsubstituted ethoxylated mono- and dialkylamines and their salts with mineral acids and fatty acids, for example hexyl Amines, octylamines, isononylamines, oleylamines, dipropylamines, diisopropylamines or dibutylamines, substituted or unsubstituted ethoxylated alkanolamines, for example mono-, di- or triethanolamines, N, N'-di-n-butylaminoethanol or 1,1'-iminodipropan-2-ol, cyclohexylamine, benzimidazole and hydrogenated tolutriazole, and nitroaromatic Compounds such as 3-nitrobenzaldehyde.

Said corrosion inhibitor (b) is preferably present in an amount of from 0.001 to 10% by weight, in particular from 0.001 to 5% by weight, in the hydraulic hydraulic fluid according to the invention, in particular for the vehicle braking fluid.

In a particularly preferred embodiment, the hydraulic hydraulic fluid, in particular the vehicle braking fluid, according to the invention is in addition to 1H-1,2,4-triazole (a) 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- 0.001 to 5% by weight, in particular 0.001 to 0.5% by weight of one or more compounds from the group consisting of furfurylaminopurine and, if necessary, further corrosion inhibitors other than component (a) as further corrosion inhibitors (b) do. Such purine derivatives are described in German patent application P 100 26 010.1 as nonferrous metal corrosion inhibitors for hydraulic hydraulic or braking fluids.

In each case all weight percentage data provided above and below relate to the total amount of hydraulic fluid or braking fluid unless otherwise indicated. In each case the above and The sum of all components listed below is added up to 100% by weight.

In particular, the invention relates to a vehicle braking liquid comprising said component (a) as a corrosion inhibitor and, if necessary, component (b).

In a preferred embodiment, the vehicle braking liquid according to the invention comprises 0.1 to 97% by weight, in particular 30 to 97% by weight of at least one polyglycol ether and / or its borate salt, in addition to component (a) and, if necessary, component (b) %, In particular 50 to 97% by weight.

Suitable polyglycols here are in particular ethylene glycol monoalkyl ethers having an ethylene oxide unit of 6 or less and having 4 or less 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. In addition, ethylene glycol dialkyl ethers and propylene glycol dialkyl ethers having up to 6 ethylene oxide units and having up to 4 carbon atoms in each alkyl radical, such as triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, di Ethylene glycol di-t-butyl ether, diethylene glycol dibutyl ether, diethylene glycol di-t-butyl ether or dipropylene glycol dimethyl ether are also suitable.

Suitable boric acid ethers of these or other polyglycols are, in particular, EP-B 013 925 (ring bisboric acid esters), DE-C 28 04 535 (nitrogen containing boric acid ethers), DE-A 24 38 038 (alkylene borates) Monoalkyl ether esters) and DE-B 17 68 933 (boric acid trialkoxyalkyl esters).

Instead of the polyglycol ethers and / or boric acid esters thereof, the vehicle braking liquid according to the present invention may include those based on carboxylic acid esters, mineral oils or silicone oils as main components.

In another preferred embodiment, the automotive braking fluid according to the invention comprises from 0.1 to 50% by weight, in particular from 1 to 40% by weight, in particular at least one polyglycol in addition to component (a) and, if necessary, component (b) In particular, it further comprises 5 to 30% by weight.

Suitable polyglycols here are relatively high boiling products of the reaction of ethylene oxide and / or propylene oxide and / or butylene oxide with water or diol, in particular mixtures of ethylene oxide and propylene oxide and the corresponding products of water. The number of alkylene oxide units in this type of polyglycol is generally from 2 to 10.

The role of such high-boiling polyglycols is the role of lubricants, which can in essence contribute to improved temperature / viscosity behavior. Polyglycols provide low viscosity polyglycol ethers with sufficient viscosity at high temperatures, thus ensuring adequate lubricity. Proper lubricity is essential for components of automotive braking systems because rubber or elastomers must slide on metal with very low wear in such systems.

Further components and auxiliaries in the braking fluid for vehicles according to the present invention may be conventional antioxidants such as phenothiazine and / or phenol as main components, and conventional antifoaming agents.

The braking liquid according to the invention may also comprise the cyclic carboxylic acid derivatives mentioned in WO 00/65001, which is suitable as a component for reducing the low temperature viscosity in the presence of water.

The presence of such small amounts of 1H-1,2,4-triazole makes it possible in an excellent way for the hydraulic hydraulic fluid or vehicle braking fluid according to the invention to meet the above-mentioned requirements, in particular a generally good corrosion compared to the prior art. Behavior, ie for metals such as iron, steel, tin plates, cast iron (gray iron), lead, tin, chromium, zinc, aluminum, magnesium and their alloys, and for non-ferrous metals such as copper and their alloys such as brass If corrosion protection is to be carried out.

Another advantage of the hydraulic fluid or vehicle braking fluid according to the invention is their preferred low temperature viscosity, good water solubility, mild pH, good low temperature, high temperature and oxidative stability and good chemical stability, rubber, plastics, glues, fibers , Good behavior (ie good compatibility) with materials such as elastomers and rubber steel and similar materials, as well as good lubrication behavior.

The use of only a small amount of 1H-1,2,4-triazole in the hydraulic hydraulic fluid or vehicle braking fluid according to the invention has a number of advantages from an economical and ecological point of view.

The following examples are intended to illustrate the invention but not to limit it.

Commercially available DOT 4 or DOT 5.1 brake fluid BF 1 (ERBP: 267 ° C, wet ERBP: 173 ° C, -40, respectively, with 0.05% by weight of 1H-1,2,3-tolutriazole as non-ferrous metal corrosion inhibitor) Brake fluid BF 1a according to the present invention based on the kinematic viscosity at 캜: 676 cSt) and BF 2 (ERBP: 263 캜, wet ERBP: 181 캜, -40 캜: kinematic viscosity: 850 cSt) as main components , BF 1b, BF 1c and BF 2a were compared and tested.

BF 1:

55.00 wt% triethylene glycol methyl ether borate,

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,

1.51% by weight of a mixture of 1,1'-iminodipropan-2-ol, phenothiazine and phosphate ester,

0.05% by weight of 1H-1,2,3-tolutriazole.

BF 2:

68.00 wt% triethylene glycol methyl ether borate,

28.84% by weight of a mixture of triethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether and diethylene glycol,

3.11 wt% of a mixture of 1,1′-iminodipropan-2-ol, phenothiazine and phosphoric acid derivatives,

0.05% by weight of 1H-1,2,3-tolutriazole.

The braking solutions BF 1a and BF 2a according to the present invention are replaced by only 0.05% by weight of 1H-1,2,3-tolutriazole by an equivalent amount of 1H-1,2,4-triazole; Braking liquid 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; The braking liquid BF 1c according to the present invention contained 0.07% by weight of 1H-1,2,4-triazole instead of 0.05% by weight of 1H-1,2,3-tolutriazole (triethylene glycol monomethyl ether borate was only 54.98 Weight percent), different from BF 1 and BF 2 only.

Application studies were performed according to the 2000 version of PSA Peugeot-Citroen D 53 5387 copper corrosion test. In this test, a copper sheet having a total surface area of 1000 cm 2, pre-washed with acetone, was bent in the form of a round cylinder in such a way that the inner metal surface itself did not contact. The copper sheet was placed in a mixture of 294 ml of a braking liquid containing 6 ml of distilled water and heated to 100 ° C. for 100 hours; 10 liters / hour of air previously passed through distilled water cooled to 2 ° C was passed through the hydraulic working liquid. After the test, the appearance of the unwound copper sheet and the appearance of the hydraulic fluid were visually evaluated, and the copper content of the hydraulic fluid was measured.

The results from the tests described are shown in Table 1 below.

Cu content [mg / kg] Cu sheet appearance Hydraulic working fluid pH BF 1 (comparative): 24 Thick coating Turbidity, sedimentation 7.4 BF 1a: 29 Bright, no coating Amber, sunny 7.6 BF 1b: 34 Bright, no coating Amber, sunny 7.6 BF 1c: 18 Bright, no coating Amber, sunny 7.5 BF 2 (comparative): 10 Thick coating Turbidity, sedimentation 7.6 BF 2a 30 Bright, no coating Amber, sunny 7.7

In contrast to conventional braking solutions such as BF 1 and BF 2, the formulations according to the invention not only provide a very good copper way with a low Cu content in the test hydraulic fluid, but also produce a metal surface without a coating. It can be seen that there is no sedimentation formation in the braking liquid.

In addition, the results shown below for the corrosive test according to SAE J 1704 (January, 97) indicate that the braking fluid according to the invention, such as BF 2a with a low 1H-1,2,4-triazole content, is in accordance with the invention. Formulations, such as BF 1d, which have a high 1H-1,2,4-triazole content, show that they show better corrosive results in the case of copper (BF 1d shows BF 1 Correspondingly, it comprises 0.20% by weight of 1H-1,2,4-triazole in place of 1H-1,2,3-tolutriazole and only 54.85% by weight of triethylene glycol monomethyl ether borate) .

The results from the corrosive test according to SAE J 1704 (January 97) are shown in Table 2 below.

metal BF 2a weight change [mg / cm 2] BF 1d (comparative) weight change [mg / cm 2] Tin 0.00 -0.01 River +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

Claims (7)

(a) 0.005 to 0.125 weight percent of 1H-1,2,4-triazole, and (b) 0 to 10% by weight of one or more additional corrosion inhibitors (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 1H-1,2,3-triazole is at least 4: 1. Hydraulic working fluid improved corrosion resistance including a. The hydraulic fluid of claim 1, wherein the component (a) comprises 0.005 to 0.08 weight percent. 3. Hydraulic fluid according to claim 1 or 2, comprising component (a) as the only triazole-based corrosion inhibitor. The method according to claim 1 or 2, wherein as component (b) benzimidazole, hydrogenated 1H-1,2,3-tolutriazole, purine, adenine, 6-chloropurine, 2,6-dichloropurine, 6 0.001 to 0.5% by weight of one or more compounds from the group consisting of -methoxypurine, 1H-1,2,3-triazolo (4,5-b) pyridine, 6-histaminopurine and 6-furfurylaminopurine And, if desired, further corrosion inhibitors other than component (a). A vehicle braking liquid comprising the component (a) of any one of claims 1 to 4 as a corrosion inhibitor and, if necessary, the component (b). 6. The vehicle braking liquid according to claim 5, further comprising 0.1 to 97% by weight of one or more polyglycol ethers and / or boric acid esters thereof, in addition to component (a) and, if necessary, component (b). 7. The vehicle braking liquid according to claim 5 or 6, further comprising 0.1 to 50% by weight of at least one polyglycol in addition to the component (a) and, if necessary, the component (b).