DE1925826C - Power transmission fluids - Google Patents

Description

The invention relates to the use of superior synthetic hydrocarbon liquids in devices in which mechanical forces are transmitted or absorbed, e.g. B. in automatic Power transmission devices (e.g. motor vehicle transmissions), hydraulic systems, shock absorbers, hydraulic control devices, clutches and mechanical devices other than power transmission fluids with improved lubricating properties.

In addition to the development of various power transmission devices, there was a need to Prepare suitable fluids that perform essential functions in the work of these mechanisms perceive. The operation of these complex mechanisms often requires that the Fluid works in several different functions. The liquid is not only used as a lubricant and coolant to reduce friction and the heat developed during the work process, instead, it continues to perform other key functions. In the case of automatic power transmission and the hydraulic actuation of the various mechanical components of the drive unit in motor vehicles, for example, the fluid acts hydrokinetically in the fluid coupling or the torque converter, depending on the type of transmission.

In most hydraulic systems, the hydraulic fluid must in addition to the implementation Their primary function of power transmission also lubricates the rubbing parts of the system. To the Parts lubricated in this way include the rubbing surfaces of the liquid pump, working pistons. Cylinders, valves and fluid motors. Many of these components are intricate mechanical ones Devices.

For conventional automatic power transmission devices, hydraulic systems in industry. Gear reducers and the like are generally used as functional fluids based on naturally occurring oils of mineral origin. It is well known, however, that such mineral oils, even after refining, do not have the properties necessary to meet the performance requirements in such devices. It is therefore common practice to add small amounts of other materials to these base materials in order to influence one or more properties of the same. It has become difficult because of the many increasing performance demands placed on functional fluids. Finding additives that still perform the functions for which they are added without creating other problems, such as increasing corrosion or causing harmful deposits.

The useful life of each functional fluid can generally be adjusted based on certain criteria such as the degree of viscosity increase, the degree of corrosion on metal surfaces in contact with the fluid, and the degree of deposits. The useful life of the working fluid is of great importance for modern automatic power transmission devices. The requirements placed on fluids for automatic power transmissions, for example gearboxes, have become higher in recent years to the extent that the horsepower of the new motor vehicles has increased. At the same time, efforts have been made to extend the recommended period between changing the transmission oil. The requirements with regard to oxidation stability have become particularly critical. The formation of sludge and varnish, which are symptomatic of the oxidation, create serious work problems with the complicated transmission mechanisms.

In the modern fluids for automatic power transmission are therefore highly refined Mineral oil base materials with incorporated multi-purpose additive mixtures ("packages") are used

Even the mineral oils developed with moderate additives, however, linger over a long period of time often at the lower performance limit of their behavior when they are among the automatic ones Powertrains in current automobiles

occurring thermal and oxidative forces are subjected.

The known synthetic base materials turned out to be fluids for automatic power transmissions compared to mineral oils only in

Slightly competitive, primarily because the synthetic fluids often do incompatible with conventionally used materials in mechanical power transmission systems are.

For example, many synthetic fluids are known to cause corrosion, when brought into contact with conventional metals, and that they have adverse effects on certain non-metallic materials.

Many synthetic hydrocarbon compounds would be with regard to their material compatibility acceptable but often unsuitable because of their viscosity properties. The liquid viscosity is a critical property in most power transmission systems. She is special Significance in systems that are subject to extensive changes in the ambient temperature are, such as B. in power transmissions in automobiles. It has therefore been accurate and sophisticated Agony ink? tion standards for liquids for automatic Power transmission set. The viscosity properties are under these standards on most rigorously tested.

Well-known hydraulic fluids such as B. in U.S. Patent 3,290,253 are described, consist of chlorine-substituted diarylalkanes or provide stabilized normal automatic power * Transmission fluids, such as B. according to French

5 $ sischer patent specification 1 470 070 and Belgian patent specification 654 657. These known hydraulic Liquids now show considerable disadvantages in terms of costs and performance. this is based on the following consideration of the

different viscosity properties of each other to be compared power transmission fluids, taking into account that the viscosity is one of the most critical variables in an automatic power transmission fluid (ATF). For assessment

In order to improve the performance of power transmission fluids, the gearbox manufacturers have drawn up appropriate standards to which the power over carrying fluids must suffice. Gene's *

ra! Motors for Dexron (Registered Trade Mark) Those used in accordance with the present invention

established standard is the following: synthetic liquids are dicyclohexyl compounds

_OQan ..., _nn fertilize which is replaced by a tetraalkyl-substituted alkyl

™ 'Vwkositatsmimnnim 7,0, lengruppe are connected. Each of the Cyclohexylnnge "Sor * ^ ositätsmaximum 400a j _kan have ⁸ _ne ^H _inen alkyl substituents.

-29 C, viscosity maximum 55,000. _{Those used as} power transmission fluids

The automatic power transmission fluids synthetic fluids correspond to the general

But not only must these viscosity standards meet the formula

len, but they must also have a small ASTM viscosity drop have and against oxidation io

R ₁ R ₂

be constant. This is the case with the power transmission X ^ \ q c ζ Η ^ S

state-of-the-art liquids not of the \ / II \ - ~ /

Case. Also included in U.S. Patent 3,290,253 r jL

^{chlorosub- 3} described in Examples 3 to 10

substituted diarylalkanes a much higher 15 in which the radicals R ₁ , R ₂ , R ₃ and R ₄ Cj- to C ₃ -AIkVl-

AST M drops from 0.86 to 0.95 and have extra-groups and can be the same or different

the viscosity., which either at 99C below NEN, and in which the radicals R ₅ and R ₆ C ₁ - to C ₂ -alkyl

the norm, or at the lower temperatures far groups and / or hydrogen mean and the same

are above the norm. In particular, they have or can be different.

in Examples 3,6.9 and 10 of U.S. Patent 20 The 2,3-dicyclohexyl-2,3-dimethylbutane is preferred in the power transmission fluids described in 3,290,253 of the present invention as th pour points of -31.6 C or higher and ge - Power transmission fluid used. It can therefore not meet the performance requirements at lower temperatures due to the oxidative coupling of cumene. The hydrogenation following in Examples 4.5 and 7 are prepared,
The power transmission fluids described have 25 Other fluids according to the present invention, on the other hand, unsatisfactory viscosities are, for example, the 3,4-dicyclohexyl-3,4-dibat 99 C. Although the low-temperature methylhexane and 2,3-di- (4-methylcyclohexyl) -2,3-ditur data not given, the relatively high methylbutane.

Viscosity at -4 ¹ C shows, however, that the lower The conventional fluids for automatic temperature properties of these power transmission fluids are usually insufficient on hydrocarbon oils. In addition, include those described in the generally on paraffin hydrocarbons, on the USA patent mentioned, chlorine-built. The addisubstituted diarylalkane compounds with a derivative combination incorporated into this basic material is designed in such a way that various hydrogen atoms are present on the alkane bridge. some kind of effects can be achieved. A major part of the structure that results in poor oxidation resistance of the additives present in the composition. acts multiple times, so it's not absolutely necessary

This also applies fo ^p in the French patent is Jer. to use a separate additive for each purpose,

font 1 470 070 and the Belgian patent specification In the case of liquids for automatic

654 657 described inventions. Most common additives used in French power transmission

see patent specification 1 470 070 is an additive pack 40 is oxidation inhibitors, dispersants

for automatic power transmission fluids. Metal deactivators, viscosity index

wrote that a three-component mixture of better. Agent against wear and abrasion, rust

a phosphorus compound, an alkylphenol and inhibitors. Corrosion inhibitors, foam inhibitors

contains a vinylpyrrolidone copolymer. These. Swelling agents for sealing and friction modi-

This additive is intended for the automatic power transmission.

liquid a long-lasting oxidation »- The physical conditions in the modern give resistance. That means, with other woraromatic power transmission mechanisms, that the known power transmission fluids are responsible for the oxidation of the working fluid only through special additives that are resistant to oxidation. The rapid flow of fluid through which must be made. This is in terms of * j> unit, the liquid and air into intimate Kon-price and ease of manufacturing a corresponding clock brings the high fluid temperatures and distinctive disadvantage to the later, the catalytic effect of the various metals power transmission fluids described do not own . all work together to promote oxidation

According to the present invention has now been accelerated. The result of the uncontrolled oxy-

the broad range of synthetic hydrocarbons dation is the formation of varnish, sludge and organic

substances a class of niche acids linked by alkylene, the latter compared to the

Acyclic compounds found that are potentially corrosive in Kraft metal components, additional Transmission mechanisms, especially in automatic borrowed, the liquid can be excessively thickened and

see gears that behave much better than those that adversely affect their behavior,

previously used synthetic hydrocarbons. 60 As a well-known qualification standard for liquid

five automatic power transmission mechanisms that can be used in accordance with the present invention.

synthetic fluid has an oxidation stability are here the »General Motors Standards for

acted on that of a well-known liquid Automatic Transmission Fluid, Type A suffix A «

for automatic power transmission mineral original specified. As in newer transmissions and machines

jump is superior. This $ 6 synthetic fluid with higher performance has greater demands on the

also has viscosity properties that make them easy to put fluids for power transmission,

The General Motors Corporation has introduced new liquid

Make the fundraising adaptable. developed which is called "Dexron"

I 925 826

will. "Dexron" is a registered trademark, the fluid standard for power transmission of the door General Motors. It is an improvement on the type A suffix A norm.

A liquid of the dexron type was used here as a comparative liquid to that used in the present invention Compared to 2,3-dicyclohexyl-2,3-dimethylbutane. The reference fluid was one of the Dexron norm Corresponding mineral oil-based hydrocarbon containing an additive combination. the synthetic liquid 2,3 - dicyclohexyl - 2,3 - dimethylbutane contained 1 percent by weight of 2,6-di-t-butyl-p-cresol.

About the superior oxidation stability of 2,3-dicyclohexyi-2,3-dimethylbutane An oxidation and corrosion test according to the »Military Specification No. 7808 D «, a recognized test standard that was developed to ensure stability Measure synthetic lubricant for turbines. In general, in this experiment, the inhibition time the oxygen consumption, the fluid loss, the increase in viscosity and the Change in physical appearance of a liquid sample measured after looking over it a specified period of time at a constant temperature in a stream of dry air in the presence of Exposed to metals such as aluminum, copper and iron. The time of exposure to the dry AircUomes and the temperature can be varied.

In the following Tables I, II, III and IV the comparison oxidation and corrosion behavior of the reference liquid Dexron and one preferred synthetic liquid of the present invention, namely 2,3-dicyclohexyl-2,3-dimethylbutane set out. The following test conditions were based on the figures in Tables I to IV based on:

Sample size 200 ecm

Air flow 5 1 / h dry air

Temperature 175 ° C

Suspension time .. 48 hours

Existing metals Al, Cu, Fe

Table I.
Acidity

liquid At first-
Total acid
number end
Total acid
rahl Dexron fluid
2,3-dicyclohexy! -2,3-di-
methylbutane 1.61
0.09 3.9
0.5

Table 11 Increase in viscosity at 37.8 ° C

liquid Start '
viscosity
cSt End
viscosity
cSt percent
sentence of
Viscous!-
activity
increase Dexr on fluid ....
2,3-dicyclohexyl-
13 »dirnethvlbutane 39.03
29.51 52.84
30.50 35.4
3.3

Table III
Coke and sludge formation

liquid coke Bad Dexron fluid
2,3-dicyclohexyl-2,3-di-
methylbutane No
No medium
No

Table IV
Change in weight of metal samples

liquid
'5 aluminum
mg / cm ² iron
mg / cirr copper
mg / cm ² Dexron liquid ....
2,3-dicyclohexyl-
2,3-dimethylbutane + 0.02
0.00 + 0.01
0.00 -0.32
+ 0.01

From the figures in Tables I to IV it can be seen that the synthetic liquid to be used according to the present invention, namely 2,3-dicyclohexyl-2,3-dimethylbutane, gives superior results compared to the reference liquid Dexron. With particular reference to Table IV, it should be emphasized that the dexron fluid exhibits a significant amount of copper corrosion, as evidenced by a weight loss of 0.32 mg / cm ² on the copper test sample. The synthetic hydrocarbon 2,3-dicyclohexyl-2,3-dimethylbutane, on the other hand, showed no measurable weight loss in the copper sample with which it was in contact. These corrosion results are corroborated by the comparatively high total acid number which can be ascribed to the dexron liquid according to the figures given in Table I.

The importance of the viscosity properties of an automatic transmission fluid has already been emphasized. It is necessary that a fluid for automatic transmissions or for automatic power transmission Meets certain initial viscosity standards. It follows that a change in viscosity properties during use can be little should. Referring to the results in Table II, it can be seen that the viscosity of the Dexron fluid decreased by 35.4% at 37.8 ° C during the 48-hour oxidation and corrosion test increased. This contrasts with an increase in viscosity of only 3.3% in the case of 2,3-dicyclohexyl-2,3-dimethylbutane.

The superiority of 2,3 * dicyclohexyl - 2,3 - dimethylbutane as a power transmission fluid was further illustrated by a second oxidation and corrosion test which was carried out under the same conditions described above. At the point where 1 percent by weight of 2,6-di-t-butyl-p-cresoI was added, 10 percent by weight of the same additives were added to the synthetic base material.

tive combination added, as it is in the Dexron liquid, the viscosity increase at 37.8 ° C was only 2.1% after 48 hours and no sludge was detected. However, the presence of the dexron additive combination caused an un-

desired increase in acidity, the total acid number being 1.15 at the beginning of the investigation and 2.6 at the end of 48 hours. The copper weight loss caused thereby was 0.04 mg / cm ² .

7 * ■ 8

These numbers are much higher than the results of the statistical test.

of Tables 1 and IV, here the synthetic cyelöheityl compounds which can be used according to the invention

liquid did not contain any additive combination. Apart from its viscosity, it is also dufeh

therefore note that the addition of certain her * other additives will be improved. Sometimes köttifliltehef additives that are useful with mineral oil 5 require small amounts of de-icing agent to be camouflaged

can, the behavior of 2,3 * Dieyclohexyl * 2 ^ di * sealing, BntsehäuniungsaddHlve, additives against

«EthylbWn and other synthetic liquids, abrasives, dispersants, dyes and others

those created according to the present invention who * useful substances of the power transmission fluid *

the. can adversely affect. ability to give up. insofar the expert must answer the question

The standard of the DexronflUsstgkait calls for a mini- ■ <> Investigate whether certain conventional additives have a viscosity at 99 "C of 49.0 SUS. the 7.0 cSt possibly also corresponds to several properties of the invention. It requires a maximum Brookfteld synthetic liquids that can be used to improve viscosity of 400 o cSt at 2. VC and 33 00 o cSt But it should be emphasized that, for example at -40 C. The viscosity properties for 2..VDi- 2,3-dicyclohexyl-2,3-dimethylbutane because of its cyclohexyl-2.3-dimethyl butane with 1 percent by weight 'S excellent oxidative stability and viscosity * 2,6-Di-t-butyl-p-cresol were as follows. properties for use in automatic 4.826 cSt at 99 C. Gears with a minimum amount of additive 32.01 cSt at 37.X C. can be treated. The same goes for everyone 3,150 cSt at - 17.8 C *. other devices of automatic power over -19,000 cSt at - 29 t «load.

When adding a small amount of viscosity «· The unexpected oxidation and viscosity bar-

index improver would be 2.3 - dicyclohexyl 13 dtitit of the dicyclo-

methylbutane the viscosity specifications of the Dexron hexyielkanverbindungen is determined by a comparison

conform to standard. There are many viscosity dexes of 2.3-dicvflohexyl-2.3-dimethylbutane with others, vrr rar use with the liquids * 3 outside the discovery range * by

suitable for the present invention. Outstanding results, alkylene-based alicyclic compounds

are obtained with polyalkyl methacrylates obtained by tert. The starting point was the previous one

Polymerization of alkyl methacrylates, their alkyl oxidation and corrosion tests described

groups about 2 to 16 or I to 18 carbon generation processes with the essential exception that

atoms can contain. This TP a 20 g sample is used instead of 200 ecm

Alkyl groups can, for example, be the ethyl. Pro-was. A 20 g sample of each compound was

pyl-. Butyl. Amyl or hexyl group etc. and for 48 hours at 175 C in a dry air-

Be mixtures of the same. The number of coal streams of S I / h. in the presence of various metals Substance atoms should be so high that the polymer is exposed. The main ones to be considered

is compatible with the liquid batch material. 35 variables were the time of inhibition. the

The alkyl group is preferably normal alkyl oxygen consumption, fluid loss and the

group, but can also be a branched chain or increase in viscosity at 37.8 C under inhibi-

Be a cycloalkyl group. The molecular weight of the exposure time is understood in Polyalkyl methacrylate should be sufficiently large. around which the sample begins to oxidize, d. h .. in the

the viscosity of the base material increases accordingly ψ » a repeated response when measuring the

hen, on the other hand, sufficient oxygen intake is determined. In case of

be low in order to ensure compatibility with the explanation given by alkylene

Can guarantee liquid approach matertal. bound compounds was the 2,3-dicyclo-

Except for an example of a suitable viscosity index ratio - the inhibitors. the duration of the aging period for use in 2,3-dicyclohexyl is less than the duration of the 48-hour-2,3-dimethylbutane and other experiments which are appropriate according to the invention. Each of the compounds was tested without reversible liquids, a mixed additive is tested, with the exception that 1 weight polymer of butyl and lauryl methacrylate with percent 16-di-t-butyl-p-cresol as an oxidation compound with a molecular weight of about 40,000. A bitoT was admitted. The purpose of the further oxidation example is a terpolymer of butyl 5 ° inhibitors, the compounds in question methacrylate, lauryl methacrylate and vinyl pyrrolidone. to impart sufficient stability to wherein the molecular weight is about 40,000. This way, meaningful qualitative results are obtained. Another viscosity index improver is polyisocyanate oxidation and corrosion tests on butylene with a molecular weight between 20,000. It was found that. if such and 40,000, which by means of acid-catalyzed polymer compounds with low stability is not a cation of isobutylene. Furthermore, a small, specified amount of inhibitor is added, polyalkylstyrene can be used, which is produced by polymerization, the inhibition time is excessively short in the Vervon alkylstyrene, the alkyl ratio being the total exposure time of 48 hours, preferably lauryl and the molecular weight for reasons of uniformity of the test of the polymer 45 000 to 50,000. In another implementation, a copolymer of inhibitor was therefore added to all the testers of usable viscosity index improvers of the preconditions. Because of the exceptional vinyl acetate and AJkylfmnarat with a molecular behavior of 23-di <weight 7clohexyl-2,3-dirnethylbutan between 40000 and 60000. alkyl acrylates, in which oxidation and corrosion test vne ethyl acrylate and octyl acrylate as 65 can and because of the still existing Purity after being used. 48 hours would consider this connection «Oxy-

For certain purposes, such as for the resistance to dation even without the Y ^ rhan- Application of the power transmission fluid in the autosein of an inhibitor.

The results of a comparative oxidation and koffosioftsufitefitefung with alkylene ver · btifldefiefl alieyelisehen connections are in the Table V below. The total oxygen consumption, the increase in viscosity and the Loss of fluid became off after 48 hours * put the probe air all the connections established.

Table V Oaydation and viscosity properties of the acyclic compounds linked by an alkylene

connection

2 ^ * Dicyefohexyl-2J "dimethyIbutane l, l-Dteyekihexyl-2-Methytpropen

1,1-cyclohexylpentane

1,2-dicyclohexyl propane

1,4-dicyclohexylbutane

(Hours)

48 18th 29 26th 27

SaueMtoffwbrawh (g O ₁ / g Suhstfal)

0.0

0.1165

0.1278

0.1603

0.2148

Vfekmititocrhelttmg be »J7.rc

2.7 190.3 111.8 241.2 280.6

Loss of liquidity

1.1 2.5 4.5 4.8 6.8

In the following wild a process for the production of 2,3-DicyclohexyV-2,3-dimethylbutane of the before * added compound within the scope of the present invention of the following formula

H ₃ C CH,

C-C

H, C CH,

The recrystallization was carried out for the purpose of removing impurities contained in the dimerization process can occur. The dimerization of cumene results primarily 2,3-Diphenyte-Z3-dimethylbutane of the following formula

H ₃ C CH ₃

described.

2,3-dicyclohexyl-2,3-dimethylbutane

2,3-Diphenyl-2,3-dimethylbutane (378g, 1.59MoI). 25 g of 5% rhodium-on-carbon catalyst and 400 ml of methylcyclohexane were placed in a 1-1 autoclave which had previously been rinsed three times, pressed down to 84 kg / cm2 and checked for density. The material was heated to 6 (TC and pressurized to 98 kg / cm ² , at which point the exothermic hydrogenation began. The rate of hydrogenation was controlled ^{by feed controls ranging from decreases to 63 kg / cm 2} to increases to 141 kg / cm ² . at these pressures, was the reduction during a 90-minute period at 100 ° C for the most part. After this treatment, the reactants were at 200 ⁰ C, 211 kg / cm ^2. 4 hours heated to the complete reduction ensure. the cooled reaction mixture was filtered, the solvent present in excess! removed under vacuum NND the concentrates under vacuum. boiling point 135 ° C / O.O2mm. distilled. This water-white liquid, n "1.5020, was free of any trace of unsaturation, as shown by It was found to have a purity of 99.5% by vapor phase chromatographic analysis.

2,3-Diphenyl-2 ^ 3-dimethylbutane was prepared by reacting 146.2 g (1.0 mol) of di-t-butyl peroxide with 347 g (2.88 mol) of cumene. The unreacted cumene was recovered by distillation under reduced pressure (boiling point 55 ~ C / 30 mm). The concentrated reaction products crystallized after cooling. Recrystallization from ethanol gave 140 g of 23-diphenyl-2,3-dimethylbutane, boiling point 119 to 120 ^° C.

H, C CH ₃

During the dimerization process, however, certain by-products can arise from the radical attack which are impurities by their nature. A by-reaction product resulting from the radical attack on the aromatic ring during the dimerization of cumene has the following formula

CH ₃

CH,

CH,

CH,

The side reaction product resulting from the radical attack on the primary hydrogen atom has the following formula

CH ₃ CH ₃

i i

C-CH ₂ CH
CH ₃

Although the side reaction products discussed above are not in the range of general forms lying, which defines the liquids of the present invention, would be their presence as a grain components in small amounts in a reduced cumene dimer mixture for the purpose of power over Suitable because the mixture is mainly from the more oxidatively stable 23-dicyclohexyl-2,3-di methylbutane

In practice, the recrystallization steps from wirl are in the conventional method Often omitted for economic reasons. It I:

Hence the fact that the invention can be used Liquids not only through a Teiraalkyl " Substituted alkylene group linked cyclohexyl 'compounds contain as such, but also also subsidized ancillary stock products, if the $ Recrystallization step is omitted in the production of the main connection. According to the present ' Liquids that can be used with the invention contain up to about 20% reduced dimeric side reaction products of the type mentioned above. to

The following is a process for the preparation of X1 dicyclonexyl-S / Wimethylhexane, another alkylene group substituted by a tetraalkyl linked cyclohexyl ring compound of the formula

H ₃ C CH, ' ⁵

H, C ₂ C ₁ H, _M

described.

3.4-dicyclohexyl-3.4-dimethylhexane

3.4-Diphenyl-3.4-dimethylhexane (312 g. 0.12 mol, melting point 87 to 94X), 3 g of 5% ips rhodium- * s on carbon and 100 ml of methylcyclohexane were at 200 ° C. 211 kg / cm ² . Hydrogenated for 6 hours. The cooled reactants were filtered, the filtrate concentrated under vacuum and the concentrates vacuum distilled. The desired hydrocarbon. 3.4-dicyclohexyl-3.4-dimethylhexane. was collected as a water-white liquid with a boiling point mainly at 113 C 0.03 mm.

3.4-Diphenyl-3.4-dimethylhexane was obtained by reacting 146.2 g (IMoI) of di-t-butyl peroxide with 64? » g (4.8 Moll sec-butylbenzene produced. The excess secondary butylbenzene (335 g. 2.5 mol) was made by distillation under reduced pressure and with mild heating (boiling point 74 C 32 mm) removed. The concentrated reaction products were distilled under vacuum and the main fraction at 117 to 125 ° CAU mm as a colorless liquid collected which solidified upon standing (136 g). This solid was b »i from ethanol. Recrystallized at room temperature to form the meso isomer of 3,4-diphenyl-3,4-dimethylhexane, Melting point 87 to 94 C.

There is still em method for the preparation of 2,3-di- {4-methylcyciohexyl) -2,3-dimethylbutane, a further alkylene-linked cyclohexyl ring compounds within the scope of the present invention with the following chemical formula

55

60

A mixture of 2J Dimeti: jl-2 _T-3 DKP-tolyl) butane (100 g, 0:37 mol Melting point 156 to 159 ⁰ C). 5 g of 5% rhodium-on-carbon catalyst and 100 ml of methylcyclohexane were ^{heated at 200 ° C, 211 kg / Cm 2} H ₂ for 6 hours. The cooled reactants were filtered, the filtrate concentrated under vacuum with mild heating and the concentration

H ₃ C

described.

wear vakiium distilled. The desired hydrocarbon 2.3 * di- (4 * methyleydohexyl) 3.3 * dl 'methylbtitanium was collected as a water-white liquid with a main boiling point of HO ⁰ CAl mm

2;. 3'D8methyl 2 * ₍₃ * dHpMolyl> butän was prepared by reacting 292.5 g (2 MUI) Di "t'butyl * pefösyd with 1157 g (8 _v öMol) f> cymene The schüssige of 'p -Cymol (753 g, 5.6MoI) was removed by distillation under reduced pressure (boiling point - 8 ° C / 33 mm). The concentrated reaction products solidified and were purified to the desired hydrocarbon by recrystallization from heptane, melting point 136-139 ° C.

In the synthetic fluids created in accordance with the present invention, it has two Cyrfohexyl rings connecting alkylene group 2 carbon atoms in length. It was found that such a structure leads to superior oxidative stability. With methyl substituents on this alkylene group, the preferred compound 13-Dieyciohcxyl-2,3-drmethyibutane is obtained. Ethyl and propyl substituents on the alkylene group are also present Within the scope of the present invention. It has also been found that each of the two cyclohexyl rings is substituted by a methyl or ethyl group can be.

For certain purposes it can be advantageous to use a mixture or a mixture as the base material of one or more of the synthetic compounds according to the invention to be used. So can a desired balance of physical properties with other compounds versus one single connection can be achieved.

In the practice of the present invention, it is also advantageous as a liquid base material to use the compounds disclosed here, which one an additive combination and possibly also admixing another synthetic liquid outside the scope of the invention. The liquids which can be used according to the present invention can therefore optionally only be RO percent by weight - based on the total mixture contained in the power transmission fluid '.

When the synthetic compounds according to the invention are used in conventional automatic power transmission devices as a working fluid, they can normally be used in the outer housing of the Uberuagungseinheit available being. This is connected to the typical crankshaft and the flywheel and rotates With. In the liquid there is a coupling consisting of an impeller that connects to the outer casing and a turbine is connected, which in turn is connected to the drive shaft of the vehicle? connected is. the The turbine is powered by the hydrokinetic energy of the fluid as a result of the rotation of the impeller « driven as the housing to which the impeller is connected is activated by the crankshaft and flywheel.

Although ^ S-dicyclohexyl - ^ - dhnethylbutane, wii It has been shown here that automatic fluid is particularly beneficial for power transmission, win thereby the usefulness of others according to the Er Finding usable compounds not restricted The excellent viscosity properties ten as well as the oxidation stability of 23-Dicyclc hexyl-23-dimetby: butau makes it a good one

Working fluid in many other hydraulic systems and devices, a typical hydraulic system includes one or more displaceable organs and a displacing force which is transmitted to the organs by means of a working fluid, the latter being in communication with these parts, while hydraulic Systems can contain elements such as pumps, valves, cylinders, pistons and the like, the behavior and durability of the system necessarily depend on the working fluid. The viscosity properties of 2,3-Diey6lohexyl »2,3-dimethylbutane are advantageous for the power transmission in a hydraulic system with a pump that supplies the power to the system, e.g. B. in ts elnam fluid motor from a piston pump with constant or variable displacement, which is caused to rotate by the pressure of the hydraulic fluid of the system. The preferred fluid also serves to lubricate the rubbing parts of such hydraulic systems. The excellent oxidation stability of l3> Dieyetahexyl-2, MifnethylDUtan promotes the purity of a hydraulic system for setner resistance Sehlammbildung, to deposits $ 1. corrosive attack, etc.

The liquids used in accordance with the present invention are therefore useful in many types of hydraulic machines useful as hydraulic fluids. e.g. in elevators. Hoist. Win- den, lock gates. Presses, etc. They can be used in the same way as working fluid in hydraulic control devices. Fluid couplings and other mechanical devices.

Claims (3)

Patent claims: 1. Use of single compounds or a mixture of two or more compounds the general formula in which the radicals R ₁ , R ₂ , R ₃ and R _{4 are} Cj * to C ₃ -alkyl groups, which can be identical or different, and in which the radicals R ₅ and R _{6 are} C ₁ to Q-alkyl groups and / or hydrogen , which can also be the same or different, as a power transmission fluid. 2. Use of compounds of the general formula wherein the radicals R ₁ , R ₂ , R ₃ and R _{4 are} C ₁ - to C ₃ -alkyl groups and can be identical or different, according to claim 1 as a power transmission fluid. 3. Use of!, ethylbutane according to claim 1.