WO1988005460A1

WO1988005460A1 - Lubricant hydraulic fluid, in particular brake fluid, process for producing same and use

Info

Publication number: WO1988005460A1
Application number: PCT/EP1988/000042
Authority: WO
Inventors: Erasmus Froeschmann
Original assignee: Erasmus Froeschmann
Priority date: 1987-01-22
Filing date: 1988-01-21
Publication date: 1988-07-28
Also published as: EP0275351A1; DE3789055D1; ATE101411T1; DE3701780C2; DE3701780A1; EP0275351B1; JPH01501947A

Abstract

A lubricant hydraulic fluid, in particular brake fluid, with improved lubricant properties and anti-wear protection, is composed of a commercially available brake fluid with usual additives and of a combination of a least one metallic dialkyldithiocarbonate and at least one metallic dialkyldithiophosphate as lubricant additive. Also disclosed are a process for producing the same and its uses as working fluid for central hydraulic systems, in particular as brake fluid, for servo-steering, central locking, spring hydraulic systems and the levelling and ventilating hydraulic systems of vehicles, in particular motor vehicles.

Description

Lubricable hydraulic fluid, in particular

Brake fluid, process for its manufacture and its use

The invention relates to a new lubricable hydraulic fluid, in particular brake fluid, for motor vehicles based on a commercially available brake fluid with customary additives, processes for its production and its use as a working fluid for central hydraulics, in particular as a brake fluid, for power steering, central locking and fan hydraulics Level control and suspension hydraulics, in motor vehicles and generally as hydraulic fluid in other land, water and aircraft and engines.

Hydraulic fluids are important structural elements for the operation of the brakes, the steering, the opening and closing of the doors as well as other auxiliary units and the suspension on vehicles, in particular motor vehicles. Of particular importance is the brake fluid, the properties of which are essential for the design of the brake system Meaning.

The invention is explained below with reference to its use as a brake fluid for motor vehicles, but the same oer similar considerations also apply to its use as a different hydraulic fluid, in particular as a working fluid for the central hydraulics, the power steering, the Ventilhydra lik, the central locking and the suspension hydraulics and generally as hydraulic fluid in other agricultural,

Haters and aircraft, especially motor vehicles, and engines.

The brake fluid in motor vehicles must meet a wide variety of requirements, the most important of which are the following: - It should have a boiling point that is as high as possible in order to prevent the formation of vapor bubbles at the temperatures occurring in the braking system and thus the failure of the brake, - Its boiling point should last for the service life of the

System liquid remain as constant as possible, i.e. are not changed or changed as little as possible due to atmospheric influences or the prevailing operating conditions (pressure, temperature, possibly contamination),

- small amounts of water (in the order of about

2 vol .-%) must not lead to a significant reduction in the boiling point of the brake fluid contaminated with it, - the viscosity in the cold should be as low as possible, in the heat as high as possible, i.e. the viscosity-temperature index should be as favorable as possible, the brake fluid should still be functional down to temperatures of -50 ° C, ~ the compressibility should be as low as possible and as little as possible dependent on temperature and pressure,

- It should be as little as possible corrosive to the metal components of the brake system, as this will have a decisive influence on their service life. - it should have a defined interaction with the elastomer parts of the brake system, which swell only slightly under the influence of the brake fluid (especially in the case of long-term exposure) but should not shrink under any circumstances,

- it should have a favorable foaming behavior, i.e. once a foam has formed it should disappear quickly - it should have a low solubility of gases in order to avoid harmful foam formation in the event of local suppression caused by flow processes, but the "undersaturated" fluid should have a certain ability which is under pressure in the filling in the braking system absorb remaining air,

it should be miscible with property-improving additives (additives, inhibitors),

it should be insensitive to catalytic decomposition or polymerization under the influence of the finest particles of the elements contained in the braking system and in street dust,

- it should be resistant to oxidation under all temperatures in the braking system,

- it should not attack the vehicle paint excessively in case of accidental wetting,

- Any spilled liquid should be easily removed from the wetted surface and

- It should be as little toxic as possible to humans and mammals.

In the past few decades, two main groups of substances have emerged as the basis for brake fluids, which meet the above requirements to varying degrees. A liquid that everyone No requirements, in particular those that meet lubricity and wear protection requirements, have been found so far.

The best known, commercially available brake fluids are those based on polyglycol ether and mineral oil.

The brake fluids based on polyglycol ethers and their derivatives, in particular the borate esters, currently have the largest share on the world market.

Polyglycol ethers can be represented by the formula

HO- (CH ₂ -CH ₂ -O) _n -H where n = 5 to 25.

These compounds have star bonds that are relatively stable and are only slowly hydrolyzed in quite acidic media.

In practice, many variations of the above type of connection are used as components of brake fluids.

To improve the cold resistance of the brake fluids, for example, glycol ethers are also used, which are derived from propylene glycol. Thereby ether is mostly used, which are not composed of a single building block, but represent a certain mixed form. The following empirical formula can be given for these substances:

HO- (CH ₂ -CH ₂ -O) _x - (CH-CH ₃ -CH ₂ -O) _y -H

where the indices x and y lie between 0 and 25, whereby the sum of x and y does not usually exceed the value 25. The distribution of the building blocks can be irregular, which is why these compounds are referred to as "statistical copolymers".

Compounds of the above structure are present in modern brake fluids at 10 to 20% by weight, depending on the type, and contribute to improving their lubricity due to their high molecular weight.

If the substances described above are further etherified with simple alcohols (e.g. with methanol, ethanol, propanol or butanol), polyglycol ethers of the following type are formed:

RO- (CH ₂ -CH ₂ -O) _x - (CH-CH ₃ -CH ₂ -O) _y -H

wherein R is CH ₃ or C ₂ H ₅ or i- or nC ₃ H ₇ or n- or i or tC ₄ H ₉ . X + y = 2 to 4, mainly 3.

The representatives of this class of substances make up the majority of DOT3 brake fluids, depending on the type, their share is between 50 and 80% by weight. Brake fluids containing a third type of polyglycol ether, namely borate esters, have also been on the market for some years. These include in particular the DOT 4 brake fluids. They arise from the fact that the polyglycol ethers described above are subjected to a further modification to form their borate esters. The reactive OH group still present is esterified with boric acid H ₃ BO ₃ , so that compounds of the following type are formed:

R ₁ , R ₂ , R ₃ CH ₃ or C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ (all isomers), x, y and z represent a number from 2 to 4, preferably 3.

This class of compounds is contained in a proportion of approximately 40% by weight in the brake fluids according to DOT 4.

The brake fluids on the market (such as Hydraulan H 407 ^® from BASF, DOT 4 + TSA ^® from Hoechst, and Brakefluid DOT Plus ^® from Dow Chemical) consist of a balanced mixture of the three classes of compounds described above. The compounds and mixing ratios are modified to optimize the end product with regard to certain properties.

Small amounts of the usual additives are added to the brake fluids described above, which prevent corrosion, further improve the lubrication, regulate the behavior towards the elastomers of the brake system and improve the oxidation resistance. The proportion of these "inhibitors" is usually 2 to 5% by weight of the brake fluid. A general disadvantage of these brake fluids based on polyglycol ethers is that their lubricating ability is limited, ie the pressure generators, in particular the feed pumps, cylinders and the like. The hydraulic stones containing them must be lubricated separately, which entails a considerable technical outlay.

Another type of usable brake fluids are those based on mineral oil / synthetic oil. Due to the diverse requirements placed on brake fluids, only highly refined mineral oil fractions from selected crude oils can be considered for this purpose. The boiling cut must be based on the boiling point requirements on the one hand and the viscosity requirements on the other hand, whereby the use of viscosity index improvers (VI) in higher concentrations must be used. This inevitably increases the shear sensitivity of the hydraulic fluid. In such applications, in which the shear sensitivity interferes, components based on synthetic oil can be used which are less sensitive in this regard. This is mostly 'Poly-ri! -olefins with the structural formula

wherein R is n-alkyl having 1 to 10 carbon atoms

Often, oligomers of propene, n-butene-1, n-pentene-1 and n-decene-1 are used either alone or as a mixture with one another or with mineral oil-based components.

The synthetic components mentioned are relatively expensive, so that they are only used if special requirements are placed on the shear stability. The entire range of additives commonly used in the mineral oil industry, such as, for example, antioxidants, wear inhibitors, metal deactivators, detergents, dispersants, antifoams, viscosity index improvers and the like, is available for property-improving additives.

The commercial brake fluids usually contain about 5% additives, VI improvers are added up to 15%.

Until now, liquids based on mineral oil / synthetic oil for power transmission in hydraulic systems have only been used in hydraulic steering and hydropneumatic suspension. In brake systems, these fluids are only considered in special cases. A central hydraulic system for which mineral oil appears to have been predestined has so far not been able to establish itself. One of the main reasons is that brake fluids based on mineral oil and the sealing materials commonly used in brake systems based on SBR and EPDM are not compatible. Therefore, despite their good properties, brake fluids based on mineral oil or synthetic oil cannot be used on a large scale. This is not least due to the fact that they cannot be used in combination with elastomers based on SBR or EPDM, since they cause them to swell very strongly. To counteract this, it is possible to work with elastomers based on NBR, Neoprene or Viton, but these materials have a considerably smaller permissible temperature range (with a permissible continuous temperature of + 120ºC, a sufficient cooling function is only possible up to about

-30ºC), which is a clear disadvantage of a mineral oil-based brake fluid.

In view of the fact that brake fluids have to meet a large number of requirements if they are to prove themselves in practice, it has proven to be more advantageous proved to further develop the currently known and proven fluids based on polyglycol ether instead of switching to alternative brake fluids.

The object of the invention is therefore to develop a hydraulic fluid, in particular brake fluid, which offers the advantages of the fluids based on polyglycol ether, but is significantly improved with regard to its lubricity and wear protection.

It has now been found that this object can be achieved according to the invention with a hydraulic fluid, in particular brake fluid, based on a commercially available brake fluid with customary additives, which has significantly improved lubricity and wear protection and is characterized in that it is lubricating Additive contains a combination of a) at least one metal dialkyldithiocarbamate and b) at least one metal dialkyldithiophosphate.

The hydraulic fluid according to the invention, in particular brake fluid, has an unprecedented lubricating capacity and an unprecedented wear protection, so that additional, structurally separate lubrication of the components coming into contact with the hydraulic fluid, in particular brake cylinders, pressure generator pumps, feed pumps and the like; is no longer required. The wear protection achievable with the hydraulic fluid according to the invention, in particular brake fluid, is at least a factor of 4 to 2θ higher than with the commercial brake fluids without the additive according to the invention. Their wear situation is in the order of a good to very good gear oil. The hydraulic fluid keif according to the invention is therefore not only suitable as an excellent brake fluid, but can also be used to operate the power steering, suspension, central locking and as operating fluid for other hydraulic units in motor vehicles, but also in other land, water and aircraft vehicles and engines. In particular, it offers the advantage that, due to its good lubricating effect and its good wear protection, it enables all hydraulic units to be combined into a central hydraulic system, which includes both the brake hydraulics, the steering hydraulics, the suspension hydraulics, the locking hydraulics, the level control and fan hydraulics, and similar hydraulic functions and the same required feed pumps and hydraulic cylinders. Particularly preferred configurations of the lubricatable hydraulic fluid according to the invention, in particular brake fluid, are evident from the subclaims mentioned above.

An essential feature of the lubricating hydraulic fluid, in particular brake fluid, claimed here is its content of an lubricating additive which consists of a combination of at least one metal dialkyldithiocarbamate and at least one metal dialkyldithiophosphate. The lubricating additive generally makes up 0.1 to 5% by weight, preferably 0.5 to 2.5% by weight, of the total weight of the lubricating hydraulic fluid, in particular brake fluid.

The weight ratio between components (a) and (b) is generally a: b = 1: 1 to 4: 1, preferably 1: 1 to 7: 3.

Component (a) of the lubricating additive used according to the invention contains the metal dialkyldithiocarbamate and, if appropriate, one or more further metal dialkyldithio carbamates in general in a weight ratio of 5: 1 to 1: 1, preferably 2.5: 1 to 1: 1, to each other.

Component (a) of the lubricating additive is one or more dialkyldithiocarbamates of the metals copper (Cu), silver (Ag); Zinc (Zn), cadmium (Cd); Boron (B); Titanium (Ti), zirconium (Zr), tin (Sn), lead (Pb); Vanadium (V), tantalum (Ta), antimony (Sb); Chromium (Cr), molybdenum (Mo), tungsten (W); Manganese (Mn); Cobalt (Co) and nickel (Ni), the dialkyldi thiocarbamates of boron (B), nickel (Ni), cobalt (Co), manganese (Mn), vanadium (V), tungsten (W) and molybdenum (Mo) in particular are preferred

The metal dialkyldithiocarbamates used according to the invention can be represented by the general formula

wherein Me is one of the metals mentioned above and alkyl has the meanings given below.

Examples of metal dialkyldithiocarbamates which can be used according to the invention with particular advantage are the following: copper dialkyldithiocarbamates and copper bisdialkyldithiocarbamates; Silver dialkyldithiocarbamates; Zinc and cadmium bisdialkyldithiocarbamates; Boron trisdialkyldithiocarbamate; Titanium, zirconium, tin and lead tetrakisdialkyldithiocarbamates as well as tin and lead bisdialkyldithiocarbamates; Antimony, vanadium and tantalum trisdialkyldithiocarbamates, tetrakis and pentakisdialkyldithiocarbamates as well as the dialkyldithiocarbamates in which these metals are present in mixed oxidation states; Chromium, Chromium, Chromtetrakis and Chromhexakisdialkyldithiocarbamate,

Molybdenum and tungsten tetrakis, hexakis and oxybis and oxytetrakis dialkyl dithiocarbamates. Manganese bis, tris, tetrakis and hexakisdialkyldithiocarbamates; tfnd cobalt and nickel bis and tris dialkyldithiocarbamates.

Among these compounds, those are particularly preferred

Boron trisdialkyldithiocarbamates, the nickel trisdialkyldithiocarbamates, the molybdenum tetrakis and molybdenum oxytetrakisdialkyldithiocarbamates, the manganese, vanadium and tungsten tetrakisdialkyldithiocarbamates.

Component (b) of the lubricating additive used according to the invention is one or more dialkyldithiophosphates of the metals copper (Cu), silver (Aeg); Zinc (Zn), cadmium (Cd); Boron (B);

Titanium (Ti), zirconium (Zr), tin (Sn), lead (Pb) ;; Vanadium (V), tantalum (Ta), antimony (Sb); Chromium (Cr), molybdenum (Mo), tungsten (W); Manganese (Mn); Cobalt (Co) and nickel (Ni), among which the dialkyldithiophosphates of zinc, nickel, titanium, vanadium, molybdenum, tungsten and manganese are particularly preferred.

The metal dialkyldithiophosphates used according to the invention can be represented by the general formula:

wherein Me represents one of the above metals and alkyl has the meaning given below.

Metal dialkyldithiophosphates which can be used with particular advantage according to the invention are the dialkyldithiophosphates of the same metals in the same oxidation states as those above for the metal dialkyldi thiocarbamates have been listed.

Zinc bisdialkyldithiophosphates, nickel nickel and tris dialkyldithiophosphates, titanium and vanadium tetrakis dialkyldithiophosphates, molybdenum and tungsten tetrakis dialkyldithiophosphates and molybdenum and tungsten oxytetrakis dialkyldithiophosphates are particularly advantageous.

The alkyl group in the above-mentioned metal dialkyldithiocarbamates and metal dialkyldithiophosphates each contains 4 to 8 carbon atoms, so that the metal salts mentioned are still soluble in the commercially available brake fluid, examples of particularly advantageous alkyl groups include the n-, i- and tert-butyl groups; the n- and i-amyl group; the n- and i-pentyl group; the n- and i-hexyl group; the n- and i-heptyl group; and the 2-ethylhexyl group. The i-butyl group, the n-amyl group and the 2-ethylhexyl group are very particularly preferred.

Particularly preferred representatives of the metal dialkyldithiocarbamates used according to the invention are:

Bortrisdiisobutyldithiocarbamat, Bortrisdi-2-ethylhexyldithiocarbamat, Nickeltrisdiisobutyldithiocarbamat, Niekeltrisdiamyldithiocarbamat, Nickeltrisdi-2-ethylhexyldithiocarbamat, Molybdäntetrakisdi-2-ethylhexyldithiocarbamat, Molybdänoxytetrakisdi-2-ethylhexyldithiocarbamat, manganese, vanadium and Wolframtetrakis-2-ethylhexyldithiocarbamat and Kobaltbisdiisobutyldithiocarbamat.

Particularly preferred representatives of the metal dialkyldithiophosphates used according to the invention are zinc bisdi-2-ethylhexyldithiophosphate, nickel nickel and trisdi-2-ethylhexyl dithiophosphate, manganese, titanium and vanadium tetrakisdi-2-ethylhexyldithiophosphate as well as molybdenum and tungsten 2-oxy-tetrakis and molybdenum tetoxy-tetrahis and molybdenum tetoxis and molybdenum tetrakis and molybdenum . The invention further relates to a process for the preparation of the lubricating hydraulic fluid described above, in particular brake fluid, which is characterized in that Öi.e commercially available brake fluid, which may contain conventional additives, is introduced, optionally under pressure, heated to 100 to 120 ° C and the metal dialkyldithiocarbamate is added with stirring within 5 to 60 minutes, preferably within 10 minutes, then with further stirring at a temperature below 100 ° C, preferably at about 90 ° C, within 2 to 20 minutes, preferably within 5 to 10 minutes, one or more further metal dialkyldithiocarbamates are added and the metal dialkyldithiophosphate is added with further stirring at a temperature of about 90 ° C within 2 to 20 minutes, preferably within 5 to 10 minutes. The mixture obtained is then allowed to cool and is filled into suitable containers in which it can be stored, preferably in the absence of air.

The preferred metal dialky idithiocarbamate used is nickel trisdiisobutyldithiocarbamate, nickel trisdi-n-amyldithiocarbamate, nickel trisdi-2-ethylhexyldithiocarbamate, manganese, vanadium, tungsten and / or molybdenum tetrakis-2-ethylhexamate id.

Bortris diisobutyldithiocarbamate and / or bortrisdi-2-ethylhexyldithiocarbamate are preferably used as further metal dialkyldithiocarbamates.

In the practical implementation of the invention

The method has proven to be expedient to first add the nickel, manganese, vanadium, tungsten and / or molybdenum salt to the commercially available brake fluid and then the boron salt.

As Metalldia lkyldithiophosphat is preferably used

Zinkbisdi-2-ethylhexyldithiopho sph at, Ni ckeltri sdi-2- ethylhexyldithiophosphate, manganese, titanium tetrakisdi-2-ethylhexyldithiophosphate, vanadium tetrakisdi-2-ethylhexyldithiophosphate, molybdenum tetrakis or molybdenum oxytetrakisdi-2-ethylhexyldithiophosphate, tungsten tetrakis and / or tungsten 2-ethoxophosphate. Molybdenum oxytetrakisdi-2-ethylhexyldithiophosphate and nickel trisdi-2-ethylhexyldithiophosphate are particularly preferred.

Hydraulic H 407 (a commercial product available from BASF) or DOT 4 Plus (a commercial product from Hoechst AG) or Brakefluid DOT 4 Plus (a commercial product from Dow Chemical Europe) are preferably used as the commercially available brake fluid.

The invention also relates to the use of the lubricating Hydraulikflüs liquid described above as a working fluid for the central hydraulics, in particular as a brake fluid, for the power steering, the central locking, the level control, the suspension hydraulics, the fan hydraulics and other hydraulic auxiliary units for land, water and Aircraft, in particular motor vehicles and engines.

The invention is explained in more detail by the following examples, but without being restricted thereto.

example 1

According to the method of the invention, a lubricating brake fluid (sample A) according to the invention is produced from the following components:

97.2 g Hydraulan H 407 (commercially available brake fluid from BASF)

1.2 g nickel trisdiisobutyldithiocarbamate (first metal dialkyldithiocarbamate)

1.0 g boron trisdi-2-ethylhexyldithiocarbamate (second metal dialkyldithiocarbamate) 0.6 g molybdenum oxytetrakisdi-2-ethylhexyl dithiophosphate

(Metal dialkyldithiophosphate)

The commercially available brake fluid is introduced and heated to 100 ° C., then 1.2 g of the first metal dialkyldithiocarbamate are added with stirring over the course of 40 minutes at normal pressure and at a temperature of 100 ° C., after which the mixture obtained is allowed to cool to 95 ° C. and within 10 1.0 g of the second metal dialkyldithiocarbamate is added. With further stirring, the metal dialkyldithiophosphate is added within 10 min (0.6 g) at a temperature of 90 ° C.

After cooling to room temperature, a lubricating brake fluid according to the invention (sample A) is obtained.

In the comparison test described below, the brake fluid according to the invention thus produced is used

(Sample A) with the commercially available hydraulic fluid Hydraulan H 407 without the lubricating additive used according to the invention (sample A ') for their lubricating properties, in particular their wear protection properties.

Example 2

To produce a brake fluid sample according to the invention, 98 g of commercially available brake fluid (DOT 4 Plus from Hoechst AG) are heated to 108 ° C. To make this brake fluid lubricable, the following components are added: 1 g of nickel trisdi-n-amyldithiocarbamate (first metal dialkyldi thiocarbamate) 0.4 g of boron trisdi-2-ethylhexyldithiocarbamate (second metal dialkyldithiocarbamate) 0.6 g of molybdenum oxytetrakisdi-2-ethylhexyldithiophosphate

(Metal dialkyldithiophosphate)

To the commercial brake fluid heated to 108 ° C is added 1 g of the first metal dialkyldithiocarbamate at normal pressure in 10 minutes with stirring at the same temperature, then 0.4 g of the second metal dialkyldithiocarbamate is added in 5 minutes at a temperature of 95 ° C with stirring. Finally, 0.6 g of the metal dialkyldithiophosphate is added over a period of 5 minutes at a temperature of 90 ° C with stirring. The mixture obtained is allowed to cool, whereby a lubricating brake fluid according to the invention is obtained (sample B).

The brake fluid sample B according to the invention is used with the commercially available brake fluid DOT 4 Plus without the one used according to the invention. lubricating additive (sample B ') under the same test conditions subjected to the comparative test described below.

Comparison test

The lubricating properties, in particular the wear protection properties, of the brake fluid samples A and B according to the invention described above were compared with those of the commercially available brake fluid comparison samples A 'and B', the results shown in the diagrams below being obtained.

A circular disk was used to carry out the tests made of stainless steel with a diameter of 23 mm and a thickness of 10 mm, on the surface of which a drop of the brake fluid to be examined was applied. A spot made of the same stainless steel with a diameter of 10 mm was applied to the spot where the drop of brake fluid was located, which exerted pressure on the surface of the metal disc due to its loading. The metal ball was reciprocated at a frequency of 5 5 Hz over an amplitude of 1 mm for 90 minutes under load on the surface of the metal disc, the load being within the range of 50 to 150 N and the temperature within the area during the test chs was varied from 50 to 150ºC (SRV (vibrating friction wear) device, which is sold worldwide by Optimol GmbH).

The wear profile transverse to the direction of oscillation of the ball generated during the test period due to the friction between the loaded ball and the surface of the metal disc was recorded by means of a suitable recording device, whereby the diagrams given below were obtained, in which the wear height as the difference between the highest was obtained on the ordinate and the lowest point of the surface profile of the metal disk as a function of the scanning distance of the surface of the metal disk is shown on the abscissa.

In the diagrams A and B below, a profile depth on the ordinate of 1 cm corresponds to a real profile depth in the surface of the metal disc of 1 pm, while in diagrams A 'and B' the scanning device was damped so that a profile depth of 1 cm in Diagram corresponds to a real profile depth in the surface of the pane of 2.5 μm.

Diagrams A and A 'were otherwise identical Conditions recorded (load on the ball 50 to 122 N, friction frequency 50 Hz, temperature 50 to 150 ° C, friction amplitude 1 mm, test duration 90 min).

Diagrams A and A 'show the measurement results when using the brake fluid sample A according to the invention or the commercially available comparison sample A'.

While the profile depth was at most 1.3 μm in sample A according to the invention, a maximum profile depth of 13.8 μm was obtained in comparison sample A ', which means that the wear in comparison sample A' was 10 times higher than in sample A according to the invention

Diagram A Diagram A '

Diagrams B and B 'were also recorded under identical test conditions (load on the ball 50 to 112 N, test temperature 50 to 100 ° C, friction frequency 50 Hz, friction amplitude 1 mm, test duration 90 min).

In this case too, a profile depth when using the brake fluid sample B according to the invention was at most 1.1 μm compared to a profile depth when using the commercially available comparison brake fluid sample B 'of up to 13.6 μm, which means that the sample 3 according to the invention is effective with regard to its wear protection the commercial sample B 'by a factor of 12 was superior.

Diagram B Diagram B '

Although the invention has been explained in more detail above with reference to preferred embodiments, it goes without saying that it is not restricted to them, but that they can be modified and modified in many ways in a manner which is obvious to the person skilled in the art, without thereby reducing the scope of the present invention is left.

Claims

Lubricable hydraulic fluid, in particular brake fluid, process for its production and its use

1. Lubricable hydraulic fluid, in particular brake fluid, based on a commercially available brake fluid with conventional additives, characterized in that it contains a combination of a) at least one metal dialkyldithiocarbamate and b) at least one metal dialkyldithiophosphate as lubricating additive.

2. Lubricable hydraulic fluid according to claim 1, characterized in that it contains the lubricating additive in an amount from 0.1 to 5% by weight, in particular from 0.5 to 2.5% by weight, based on the total weight of the lubricating hydraulic fluid.

3. Lubricable hydraulic fluid according to claim 1 or 2, characterized in that in the lubricating additive components (a) and (b) in the weight ratio a to b from 1: 1 to 4: 1, in particular from 1: 1 to 7: 3, are present.

4. Lubricable hydraulic fluid according to one of claims 1 to 3, characterized in that it is component (a) of the lubricating additive to one or more dialkyldithiocarbamates of the metals copper, silver; Zinc, cadmium; Boron; Titanium, zirconium, tin, lead; Vanadium, tantalum, antimony; Chromium, molybdenum, tungsten; Manganese; Cobalt and nickel, especially boron, nickel, cobalt, manganese, vanadium, tungsten and molybdenum.

5: Lubricable hydraulic fluid according to one of claims 1 to 4, characterized in that component (b) of the lubricating additive is a dialkyldithiophosphate of the metals copper, silver; Zinc, cadmium; Boron; Titanium, zirconium, tin, lead; Vanadium, tantalum, antimony; Chromium, molybdenum, tungsten; Manganese; Cobalt and nickel, especially zinc, nickel, molybdenum, tungsten, titanium, vanadium and manganese.

6. Lubricable hydraulic fluid according to one of claims 1 to 5, characterized in that in the components (a) and (b) of the lubricating additive, the alkyl group contains 4 to 8 carbon atoms.

7. Lubricable hydraulic fluid according to claim 6, characterized in that the alkyl group is the isobutyl group, the tert-butyl group, the n- and iso-amyl group, the n- and iso-hexyl group, the n- and iso- Heptyl group or the 2-ethylhexyl group, in particular the isobutyl, n-amyl or 2-ethylhexyl group.

8. Lubricable hydraulic fluid according to one of claims 1 to 7, characterized in that it as component (a) of the lubricating additive Bortrisdiisobutyldithiocarbamat and / or Bortrisdi-2-ethylhexyldithiocarbamate in combination with Nickeltrisdiisobutyldithiocarbamat, Nickeltrisdiamyldithiocarbamat, Mangit , Vanadium, tungsten and / or molybdenum tetrakis-2-ethylhexyldithiocarbamate, contains.

9. Lubricable hydraulic fluid according to one of the

Claims 1 to 8, characterized in that, as component (b) of the lubricating additive, zinc bisdi-2-ethylhexyldithiophosphate, nickel trisdi-2-ethylhexyldithiophosphate, titanium tetrakisdi-2-ethylhexyldithiophosphate, vanadine tetrakisdi-2-ethylhexyldithiophosphate or molybutylphosphate, molybdenum contains ethylhexyl dithiophosphate, tungsten tetrakis or tungsten oxytetrakisdi-2ethylhexyl dithiophosphate.

10. Lubricating hydraulic fluid according to one of claims 1 to 9, characterized in that it is the commercially available brake fluid is one based on polyglycol ether.

11. lubricious hydraulic fluid according to one of claims 1 to 10, characterized in that it contains, as a conventional additive, one or more antioxidants, metal deactivators, detergents, dispersants and anti-foaming agents.

12. A method for producing the lubricious hydraulic fluid, in particular brake fluid, according to one of claims 1 to 11, characterized in that the submitted commercial brake fluid, which optionally contains conventional additives, optionally heated under pressure, to 100 to 120 ° C and with stirring within 5 to 60 minutes, preferably 10 minutes, the metal dialkyldithiocarbamate is added, then with further stirring at a temperature below 100 ° C, preferably at about 90 ° C, within 2 to 20 minutes, preferably 5 to

10 min, optionally one or more further metal dialkyldithiocarbamates are added and the metal dialkyldithiophosphate is added with further stirring at a temperature of about 90 ° C within 2 to 20 min, preferably 5 to 10 min.

13. The method according to claim 12, characterized in that as Metalldialkyldithiocarbamat Nickeltrisdiisobutyldi thiocarbamat, Nickeltrisdi-n-amyldi thiocarbamate. Nickel trisdi-2-ethylhexyldithiocarbamate, manganese, vanadium, tungsten and / or molybdenum tetrakis-2-ethylhexyldithiocarbamate and optionally as further metal dialkyldithiocarbamate bortrisdi-2-ethylhexyldithiocarbamate is used.

14. The method according to claim 12 or 13, characterized in that as the metal dialkyldithiophosphate zinc bisdi2-ethylhexyldithiophosphate, NickeItrisdi-2-ethylhexyldithiophosphate, titanium tetrakisdi-2-ethylhexyIdithiophosphate, vanadine tetrakisdi-2-ethylhexyldithiophane dithiophosphate, 2 or tungsten oxytetrakisdi-2-ethylhexyl dithiophosphate is used.

15. Use of the lubricatable hydraulic fluid according to one of claims 1 to 11 as a working fluid for the central hydraulics, in particular as a brake fluid, for the power steering, central locking, suspension hydraulics, level control and fan hydraulics, in motor vehicles.