FR2501224A1 - Hydraulic fluid with base oil contg. isoparaffin - obtd. by hydrogenating alpha olefin oligomer prepd. with Friedel-Crafts catalyst - Google Patents

Abstract

A hydraulic fluid is claimed, comprising: (i) 70-90% of a base, contg. at least 30% of Cl2-C30 (pref. C20-C30) isoparaffinic oligomer, and (ii) (the remainder) one or more additives chosen from lubricant-, anti-wear-, viscosity improving-, oiliness- and antioxidant additives. Component (i) is prepd. by oligomerisation of C6-C14 linear alpha-olefines with Friedel-Crafts catalysts and hydrogenation of the prod. The alpha-olefines are pref. prepd. by Ziegler telomerisation of ethylene. Pref. isoparaffinic oligomers are the hydrogenation prods. of the trimer or esp. the dimer of decene-1. The base may also contain an n-alkyl cyclohexane, pref. with C10-C14 n-alkyl, and/or a mineral oil base, pref. naphthenic. Fluid is used in brakes, clutches and shock-absorbers of cars; in presses, etc. The fluid satisfies French Standard NF R 12-640. It has good lubricant properties and low viscosity at -40 deg. C, and does not swell elastomers.

Description

 The present invention has for obJet a hydraulic fluid simultaneously having a set of satisfactory properties, even under severe conditions of use, especially at low temperatures.

It is recalled that hydraulic fluid means any fluid used in a control device, wherein said fluid transmits a force, or in a damped device:
Such devices can be in particular motor vehicle braking and clutch systems, hydraulic or hydro-pneumatic damping devices, central system servo pumps, presses, cylinders, etc. Hydraulic fluids must have, for example, in general, a low freezing point, a high boiling point in order to avoid evaporative losses in service, a satisfactory viscosity at all operating temperatures and in particular a low viscosity at low temperature, a viscosity index high viscosity is as constant as possible in the temperature range of use, low compressibility to ensure faithful transmission of the controls, good lubricity and good anti-wear properties to avoid uae oes mechanical contact hydraulic fluid and especially any cause of deterioration of the pumps, a good resistance oxidation, good shear stability and good compatibility with the substances with which said hydraulic fluid is in contact, especially metals and elastomers; in particular, the hydraulic fluid must not corrode the metals and dissolve or inflate the elastomer seals.

 The problem of developing a hydraulic fluid having all these qualities to a high degree is extremely difficult to solve, since the presently known bases for constituting hydraulic fluids do not have all the desirable characteristics, even when added to them. one or more additives tending to confer such or such particular property or to eliminate one or another disadvantage of the base, these additives being in particular lubricating additives, viscosimetric enhancement additives, antioxidant additives, anti-oxidant additives; wear, etc.

 It has already been proposed to use in effect a hydraulic fluid base dfaittiuée by a mixture of isoparaffins having 12 to 18 carbon atoms, these being obtained by hydrogenation oligomers of light olefins such as propylene, n -butylenes or isobutylene; such a process may also include before-hydrogenation, a separation of said polymers by distillation.

 The fluids using this base meet most of the requirements of the French standard NF R 12-640, which defines the limiting physicochemical characteristics of brake fluids used in the automotive industry, in the category of internal liquids. symbol M. They have among others, a viscosity of 1830 cSt a OC while the maximum value defined by the n @ rme is 2000 cSt.However, it appeared, when using such fluids in motor vehicle circuits circulating in cold countries, a difficulty in starting, because of too high viscosity at low temperatures, especially after a certain period of service.

 In fact, such corpus fluids can have a viscosity of the order of 1100-1200 cSt at -40 C, but they then no longer have the necessary lubricating properties in other words, the addition of the required amount of additive. lubricant to these hydraulic fluids has the incidental effect of significantly raising the value of the viscosity at -4Q C up to values of the order of 1800 to 2000 cSt, which limits the performance of use of this fluid as indicated above.

 The present invention therefore proposes to have a hydraulic fluid having good lubricating properties and whose viscosity at O0C is low, in particular of the order of at most about 1000 cSt, said hydraulic fluid must also be compatible with the elastomers and do not cause them to swell.

 In addition, mixtures of linear alpha-olefins containing generally alpha-olefins with an even number of carbon atoms and alpha-olefins with an odd number of carbon atoms, as well as alpha, are commercially available. -olefins with an even number of carbon atoms, either in the form of individual alpha-olefins or in the form of mixtures thereof.

 Tests conducted by the applicant have allowed it to be noted that such substances can not constitute acceptable bases of hydraulic fluids.

 The subsequent work carried out by the Applicant, on the other hand, made it possible to demonstrate that paraffins answering certain conditions of structure and chain length, as obtained by oligomerization and subsequent hydrogenation of certain specific alpha-olefins, constituted bases. high performance hydraulic fluids. The present invention is therefore based on these works.

 The hydraulic fluid of the present invention, with markedly improved performance compared to hydraulic fluids already known, is characterized in that it contains a proportion of 70 to 90% of a base comprising at least 30% of one or more polymers. isoparaffinic having a number of carbon atoms ranging from 12 to 30, the residual percentage, ie 30 to 10% of said hydraulic fluid, being represented by one or more additives chosen from among others lubricant additives, anti-wear additives, additives; improvement of the viscometric properties, the lubricity additives and the antioxidant additives, said isoparaffinic polymers being obtained by oligomerization of one or more linear alpha-olefins having a number of carbon atoms ranging from 6 to 14, Friedel and Crafts type catalyst and by hydrogenation of the residual double bonds of the products resulting from this polymerization.

 According to another characteristic of the present invention, the abovementioned base also comprises one or more constituent chosen from n-alkylcyclohexanes and mineral bases, in particular naphthenic bases.

 According to yet another characteristic of the present invention, the hydraulic fluid comprises a lubricant additive consisting of a complex ester, that is to say an ester of which at least two acid and alcohol costitutits is polyfunctional, in particular a complex ester of neoplyol.

According to a preferred embodiment of the present invention the base of the hydraulic fluid meets the more limiting composition below, by weight
- Isoparaffinic polymer: 30 to 100%, preferably
60 to 80%;
- n-alkylcyclohexane: 0 to 4 i, preferably
5 to 15%; and
- mineral base: O d 30%, preferably
15 to 25%.

A globabe composition of the hydraulic fluid of the invention which makes it possible to obtain the best performances is the following (percentages expressed by weight):
above-mentioned base: 70 to 90%, preferably
74 to 81.5%;
- lubricant additive
(complex ester)
: 0 to 8%, preferably
5 to 7%
- additive improving the
viscosi properties
meters): 10 to 16%, preference
12 to 15%
additive dwunctuositd: O å 4%, preferably
1 to 3% - anti-oxidant additive: O to 2% preferably
0.5 to 1%.

 Finally, in one embodiment of the hydraulic fluid of the invention, the isoparaffinic polymers of the base of said fluid comprise one or more isoparaffinic polymers having a number of carbon atoms ranging from 20 to 30; in an even more specific embodiment, the isoparaffinic polymers of the above-mentioned base exclusively comprise one or more polymers having a number of carbon atoms of between 20 and 30 and therefore no isoparaffinic polymer having a lower carbon number at 20.

 The linear alpha-olefins defined above, including the oligomerization and the subsequent hydrogenation leads to the isoparaffinic polymers of the hydraulic fluid of the inventic can be obtained from various methods known per se.

 One of these methods, which is the preferred method in the context of the present invention, consists of the telomerization of ethylene, which is carried out according to a mechanism which is neither radical nor ionic, but co-ordinated. by means of a Ziegler catalyst, especially of the triethylaluminium type; this telomerization leads, under defined reaction conditions, to the production of linear alpha-olefanes with an even number of carbon atoms. The product obtained has a very precise composition and therefore reproducible when the conditions of temperature and pressure are determined; in particular, the distribution of the chain length of the different alpha-olefins thus obtained is statistical and responds to a Poisson curve. The implementation of this method is therefore particularly appropriate to regulate not only the nature of the alpha-olefin mixture. linearly obtained, but also that of the isoparaffinic polymers of the invention, obtained from said alpha-olefins, which allowsdetermend or adjust the characteristics of the base and hydraulic fluid drifting.

 Another method, known per se, for obtaining linear alphaolefins is the cracking of paraffin waxes, this method giving rise to mixtures of olefins of various structures comprising alpha-olefin.

with an even number of carbon atoms, alpha-olefins with an odd number of carbon atoms, internal olefins, diolerines, which mixtures may further contain paraffins, etc .; under these conditions, it is obvious that the linear alpha-olefins thus obtained must be subjected to a fractionation so as to select only linear alpha-olefins having a number of carbon atoms ranging from 6 to 14 which represent the only ones. substances usable for the preparation, by ologomerization and subsequent hydrogenation, of the isoparaffinic polymers of the hydraulic fluid of the invention, as defined above.

 Of course, any other method for obtaining linear alpha-olefins giving directly or possibly leading to, optionally by carrying out an elementary treatment, linear alpha-olefins having a number of carbon atoms ranging from 6 to 14 phr; another implementation for the oligomerization and hydrogenation of said linear alphaolefins in the context of the present invention.

 As indicated above, the linear elpha-olefins that can be used to form the isoparaffinic polymers of the hydraulic fluid of the invention are the C 6, C 8, C 10, C 12 and C 14 bonded alpha-olefins obtained by telomerization of ethylene. that is, hexene-1, octene-1, decene-1, dodecene-1, tetradecene-1 or mixtures thereof, alpha-olefin the most commonly used by invention being decene-1.

The mode of polymerization must lead to the desirable length of chain and maintain the structural characteristics of the alpha-olefin monomer a For this purpose, a Friedel-Crafts type catalyst, such as boron trifluoride, is used, leading to the branched oligomers of homogeneous structure, that is to say the isoparaffinic polymers of the hydraulic fluid of the invention. These substances have the advantage of possessing excellent physico-chemical characteristics which may be predetermined depending on the conditions used for their preparation, essentially temperature and pressure, and of conferring on the hydraulic fluid, in combination with the other ingredients of these, outstanding performance
These isoparaffinic polymers (in C12 to C30) have in common the following properties:
- very good fluidity at low temperature; low viscosity and low pour point
- high viscosity index
- good thermal stability
- high flash point; high fire point and high point of self-ignition;
- minimal evaporation losses
- good compatibility with the mineral bases (mineral oils), the usual additives thereof and the various elastomers (natural rubber and synthetic rubbers).

 As indicated above, each of these isoparaffinic polymers results either from the oligomerization of an alphaolefin alone (homopolymerization) or the co-oligomerization of two or more of them.

 A particularly advantageous isoparaffinic polymer according to the invention is that resulting from the hydrogenation of the dimer of decene-1; Another isoparaffinic polymer that can be used according to the invention is that which delivers the hydrogenation of the trimer of decene-1.

 The base of the fluid according to the invention may also comprise, as indicated above, an n-alkylcyclohexane, especially an n-alkylcyclohexane whose n-alkyl chain comprises 10 to 14 carbon atoms. Such n-alkylcyclohexanes are commonly obtained by hydrogenation of the corresponding n-alkylbenzenes, which are advantageously synthesized from benzene and linear paraffins having 10 to 14 carbon atoms, by techniques known per se. Such n-alkylcyclohexane is especially n-dodecylcyclohexane.

 The mineral base which is advantageously usable in the hydraulic fluid of the invention is preferably a naphthenic base having the following characteristics: a pour point below -600C, a flash point above 820C and an index of acid less than 0.1 mg KOH / g.

 The incorporation of a complex ester into the hydraulic fluid of the invention gives better lubricating properties, as can be seen by visual inspection of the mechanical parts of the dynamic test, without harming the others. characteristics.

 As indicated above, by expression-ion "complex ester" is meant here an ester of which at least two constituent acids and alcohol are polyfunctional, the lester molecule being preferably formed by at least three constituents which are acids and / or alcohols. The presence of such a complex ester, neopolyol, provides good lubricity and good anti-wear properties.

 A study. The laboratory study, carried out according to the ASTM D 2783 standard, which specifies the conditions for determining the extreme-pressure properties of lubricants according to the "4-bead" method, made it possible to show that a complex ester with a neo structure exhibited far-improved pressure characteristics compared to a simple ester with a neo structure, having not more than one polyfunctional component. In addition, the choice of the neo structure results from the higher thermal stability of the esters having this structure.

The complex esters which can be used in the invention are therefore esters with a neo-derivative structure, in particular diols such as trimethylolpropane, neopentylglycol, monopentaerythritol and diacids with C4 to
C12 such as, for example, adipic acid, azelaic acid, pimelic acid and the like. (or their mixtures) and monoacids, saturated or unsaturated, linear or branched C4 to C22.

The table below reproduces the results obtained in various laboratory tests allowing the comparison of the behavior of simple esters, complex esters and mineral oils. It is recalled that a simple ester, as opposed to a complex ester, has not more than one polyfunctional component.

<tb><SEP> Family <SEP> Load <SEP> of <SEP> load <SEP> of <SEP> load <SEP> mol <SEP>
<tb><SEP> seizure <SEP> G <SEP> weld <SEP> S <SEP> of <SEP> Hertz <SEP><SEP> i <SEP>
<tb><SEP> (kg) <SEP> (kg) <SEP> (kg)
<tb> Single <SEP>Esters><SEP> 50 # <SEP> G <SEP># 55 <SEP><SEP> 115 # <SEP> S <SEP># 125 <SEP><SEP> 18 # <SEP> H <SEP># 22
<tb> Esters <SEP>"complex"<SEP> 63 # <SEP> G <SEP># 80 <SEP><SEP> 170 # <SEP> S <SEP># 190 <SEP><SEP> 26 # <SEP> H <SEP># 34
<tb> Oil <SEP> mineral <SEP> 56 <SEP> 140 # <SEP> S <SEP><SEP># 150 <SEP><SEP> 22,24
<Tb>

The physico-chemical characteristics of two complex esters with a neo structure are given in the table below.
Cinematic Viscos Ester A Ester B in cSt
at 100 C 21 21
40 C 166 153
- 18 C 20,000 11,000
Pour point, C - 42 - 27
Flash point, COC, C 250 270
Point of fire, COOC, C 270
Density at 200C 1.025 0.951
Refractive index at 200C 1.4622 1.4680
Acid value mg KOH / g 0.30 0.20 Percentage of water <500 ppm <500 ppm
Ester A is a complex ester of trimethylolpropane and short-chain fatty acids; ester B is a complex ester of trimethylolpropane and a mixture of fatty acids with a ring length of between C7 and C36
In order to have the best possible compatibility with the elastomers, the average acid chain length of the complex ester should preferably be equal to or greater than 12.

 In addition, the complex ester must be miscible with the isoparaffinic polymer, its viscosity must be high and its freezing point must be low. Finally, this complex ester must be stable to oxidation.

 The additive improving the viscosimetric properties of oueds is in particular a polymer of the polymethacrylate type, such a polymer having a stability stability in shear.

 The onctuosit additive is in particular a triarylphosphate while the antioxidant is an amine or phenol derivative, especially an alkylphenol such as ditertiobutylparacresol.

Of course, the hydraulic fluid of the invention may optionally contain other aid agents eglaement well known to those skilled in the art, such as corrosion inhibitors, defoamers,
The following is given by way of non-limiting example various embodiments of the hydraulic fluid of the invention.

Example 1
The hydraulic fluid having the following composition is prepared
naphthenic base N 1 with the following characteristics
viscosity in cSt: at 1000 ° C. -1.3 ° C. at 54 ° C.
- flash point (Pensky Martens): 1020 C
- density at 200 C: 0.863
isoparaffinic polymer (diene-1 dimer having been subjected to hydrogenation)
neopolyol complex ester (the one known under the trade name "Nycobase LTN 20 S"
- additive improving the visosimetric properties (polymethacrylate)
- lubricity additive (tricresylphosphate)
- antioxidant (ditertiobutyl-paracresol)
This hydraulic fluid is in the form of a limpid liauide pale yellow color; its refractive index at 200 ° C is 1.455; the amount of water it contains is less than 100 ppm.

The following table gives a number of physicochemical characteristics of this fluid, compared to those of a commercial hydraulic fluid, called fluid M, also meeting the standard NF R 12-640.

<SEP> Fluid
<tb><SEP> Method <SEP> Unit <SEP> of <SEP> Fluid <SEP> M <SEP> Standard
<tb> Characteristic <SEP> of test <SEP> example
<tb><SEP> 1
<tb> Mass <SEP> volume <SEP> NF <SEP> T <SEP> 60-101 <SEP> g / cm <SEP> 0.8342 <SEP> 0.8538 <SEP> to <SEP> note
<tb> Temperature <SEP> NF <SEP> M <SEP> 07-002 <SEP> C <SEP> 297 <SEP> 270 <SEP>>SEP> 240
<tb> boiling <SEP> 142 <SEP> 115 <SEP>><SEP> 90
<tb> Flash Point <SEP><SEP> NF <SEP> T <SEP> 60-103 <SEP> C <SEP> 0.06 <SEP> 0.12 <SEP><0.10
<tb> Indioe <SEP> of <SEP> Neutralization <SEP> NF <SEP> T <SEP> 60-112 <SEP> mg <SEP> KOH / g
<tb> Viscosity <SEP> kinematic <SEP> NF <SEP> T <SEP> 60-100 <SEP> cSt
<tb> to <SEP> - <SEP> 40 c <SEP> 980 <SEP> 2 <SEP> 000 <SEP><2<SEP> 000
<tb> + <SEP> 50 C <SEP> 12.4 <SEP> 15.5 <SEP>> 8
<tb> + <SEP> 100 C <SEP> 5.5 <SEP> 6.3 <SEP> to <SEP> note
<Tb>
Examination of this table clearly shows that the performances of the hydraulic fluid of the invention are clearly superior to those of the known fluid.

 This known fluid is based on hydrogenated propylene pentamer.

 Among the tests defined by the aforementioned standard, the Applicant has chosen one which concerns an essential property of the fluid, namely its compatibility with certain elastomers as defined by the AFNOR standard.

 The elastomers subjected to the tests are respectively a polychloroprene rubber (CR) and a nitrile rubber (NBR) which is a butadiene-acrylonitrile copolymer.

The results of this test are given in the following table for the fluid of Example 1 and for the known fluid
M, by comparison with the ranges of values defined by the aforementioned standard.

<Tb>

<SEP> CR <SEP> AFNOR <SEP> NBR <SEP> AFNOR
<tb><SEP> Time <SEP> of <SEP> the test <SEP> fluid <SEP> fluid
<tb><SEP> M <SEP> of <SEP> The e- <SEP> Standard <SEP> M <SEP> of <SEP> The e- <SEP> Standard
<tb> xample <SEP> xample
<tb><SEP> 1 <SEP> 1
<tb>#<SEP> Hardness <SEP><SEP> - <SEP> 7 <SEP> - <SEP> 8 <SEP> 0 <SEP> to <SEP> 7 <SEP> + <SEP> 6 <SEP> + <SEP> 5 <SEP> 0 <SEP> to <SEP> + <SEP> 3
<tb><SEP> max <SEP> max
<tb>#<SEP> Resistance <SEP><SEP> to
<tb> the <SEP> rupture <SEP>% <SEP> - <SEP> 22 <SEP> - <SEP> 24 <SEP> - <SEP> 40 <SEP> - <SEP> 12 <SEP> - <SEP > 8.5 <SEP> - <SEP> 10
<tb><SEP> max <SEP> max
<tb>#<SEP> Resistance <SEP><SEP> to
<tb> the stretch <SEP>% <SEP> - <SEP> 30 <SEP> - <SEP> 30 <SEP> - <SEP> 40 <SEP> - <SEP> 27 <SEP> - <SEP> 25 , 3 <SEP> - <SEP> 30
<tb><SEP> max <SEP> max
<tb><SEP>#Weights<SEP><SEP>%<SEP> 0 <SEP> + <SEP> 0.4 <SEP> 0 <SEP> to <SEP> 5 <SEP> - <SEP> 2, 8 <SEP> - <SEP> 2.9 <SEP> 0 <SEP> to <SEP> 2
<tb>#volume<SEP><SEP>%<SEP> + <SEP> 4.6 <SEP> + <SEP> 5.8 <SEP> 0 <SEP> to <SEP> 10 <SEP> - <SEP > 1 <SEP> - <SEP> 1.6 <SEP> 0 <SEP> to <SEP> 3
<Tb>
Identical tests performed on elastomers commonly used by manufacturers in the automotive industry gave results similar to the results in the table above, for the fluid of Example 1 and for the fluid M, respectively.

 In addition to the above tests, a bench test was conducted to evaluate the properties of the fluid in service and its resistance to oxidation.

 This test consists of a dynamic bench test, in which a volume of 4 liters of fluid is circulated through an orifice placed on the discharge circuit of a piston pump, at a pressure of 150 bars and at a pressure of temperature of 100 C. After a determined number of cycles, specimens are taken and subjected to analyzes.

 The evolution of the fluid is monitored by determining, by analysis of each of the samples, three precise physico-chemical characteristics, namely the viscosity at 1000C, the viscosity at -400C and the acid species; The test may be supplemented by an infrared spectroscopy examination.

The obtan results are as follows:

N <SEP> cycle <SEP> Viscosity <SEP> to <SEP> 100 C <SEP> Viscosity <SEP> to <SEP> - <SEP> 40 C <SEP> Acid Index <SEP>
<tb><SEP> fluid <SEP> M <SEP> fluid <SEP> from <SEP> fluid <SEP> M <SEP> fluid <SEP> from <SEP> fluid <SEP> M <SEP> fluid <SEP> of
<tb><SEP> Example <SEP> 1 <SEP> Example <SEP> 1 <SEP> Example <SEP> 1
<tb> 0 <SEP> 6.2 <SEP> 5.5 <SEP> 2 <SEP> 150 <SEP> 950 <SEP> 0.12 <SEP> 0.06
<tb> 1 <SEP> 500 <SEP> 6.1 <SEP> 5.3 <SEP> 2 <SEP> 350 <SEP> 1 <SEP> 000 <SEP> 0.16 <SEP> 0.08
<tb> 3 <SEP> 000 <SEP> 6.1 <SEP> 5.0 <SEP> 2 <SEP> 450 <SEP> 1 <SEP> 000 <SEP> 0.19 <SEP> 0.12
<tb> 6 <SEP> 000 <SEP> 6.2 <SEP> 4.9 <SEP> 2 <SEP> 720 <SEP> 1 <SEP> 020 <SEP> 0.26 <SEP> 0.24
<tb> 12 <SEP> 000 <SEP> 6.4 <SEP> 4.9 <SEP> 4 <SEP> 100 <SEP> 1 <SEP> 150 <SEP> 0.50 <SEP> 0.29
<Tb>
It appears from this table
that the fluid of example 1 constantly has a lower acid number than the known fluid M, throughout the duration of the test
that the lower viscosity of the fluid of Example 1 at -400C remains stable whereas that of the known fluid N degrades significantly.

 Infrared spectroscopy confirms the results obtained on the physico-chemical characteristics and shows unambiguously that the fluid of Example X is less sensitive to oxidation than the known fluid M during the aforementioned dynamic test.

Finally, the physicochemical property of the decene-1 dimer, after its hydrogenation for conversion into an isoparaffinic polymer in C20, as well as those of another isoparaffinic polymer, also usable in the hydraulic fluid of the invention, is given below. which is obtained from the trimer of decene-1.

<SEP> Index <SEP> Point <SEP> Point <SEP> Point <SEP> of <SEP> Density <SEP> at
<tb> Product <SEP> Viscosities <SEP> in <SEP> cSt <SEP> of <SEP><SEP> flash flow <SEP> fire <SEP> 15.6 C
<tb><SEP> 100 C <SEP> 40 C <SEP> -18 C <SEP> -40 C <SEP> Viscosity <SEP> C <SEP> C <SEP> C
<tb> dimer <SEP> of <SEP> decene <SEP> 1.7 <SEP> 5.2 <SEP> 52.5 <SEP> 262 <SEP> - <SEP> - <SEP> 73 <SEP> 160 <SEP> 182 <SEP> 0.796
<tb> trimer <SEP> of <SEP> decene <SEP> 3.9 <SEP> 17.3 <SEP> 340 <SEP> 2 <SEP> 537 <SEP> 130 <SEP> - <SEP> 73 <SEP > 229 <SEP> 257 <SEP> 0.819
<Tb>

Examples 2 to 6
The following table gives the composition of five other hydraulic fluids that are compatible with the present invention; the first row of percentages in this table gives the base / fluid weight ratio; the second row gives the scrapparaffin (PIP) / base, n-alkylcyclohexane (ACH) / base and mineral base (BM) / base weight ratios, the third row gives the PP / fluid weight ratios,
ACH / Fluid and BM / Fluid while the fourth row gives the Aster ratios complex / fluid, the fifth row the weight ratios edditive deterioration of the viscometric properties (AV) / Fluid, the fifth row the weight ratios additives of onctucsity or auti - wear (AU) / fluid, the sixth row the antioxidant additives (AO) / fluid, the seventh row the weight ratios other additives / fluid, these other additives being here an antirust agent and a dye, and the eighth row the Viscosities of fluids at four. different temperatures.

The particular natures of the constituents of the base are as follows
PIP N 1: product of hydrogenation of the dimer of decene-1
PIP N 2: mixture of NI PIP (715) and the product of hydrogenation of the decene-1 trimer (29%)
- ACH: dodecylclohexane
- 3M N02: naphthenic mineral base of following characteristics
- viscosity at 100 C = 1, 1, at 40 C n 2.5 at -54 ° C = 213
- flash point (Pensky Martens): 94 C
- density at 200C: 0.8512
- 3M N03: mixture of naphthenic mineral base N01 and other naphthenic mineral base of following characteristics
viscosity at 100 C = 1.1 at 40 C = 2.8 at -54 C = 95
- flash point (Pensky Martens): 1050C
- density at 200C: 0.857.

 Ester C is a mixture of 6% of complex ester B (see Example 1) and 94% of a diester. Ester D is a mixture of 20% of complex ester B and 80% of a triester.

 Additives. improving the viscometric properties, AV NO 1 and AV NO 2, are polymethacrylates.

 The lubricity additive (AU) NO 1 is tricresylphosphate; the lubricity additive (AU) NO 2 is triphenylphosphate.

 The antioxidant additives (AO) N 1 and N 2 are of the phenolic type and consist respectively of dibutyl paracresol and methylenebisditertiobutylparapenol; the antioxidant additive N 1 is of the amine type and is constituted by p, p'-dioctyl-diphenylamine.

The anti-rust additive is the commercial product "NASUL BSN mineral" and the additive coloring the product of trade name "RED OL".

<tb><SEP> Ex.2 <SEP> Ex.3 <SEP> Ex.4 <SEP> Ex.5 <SEP> Ex.6
<tb><SEP> Base / fluid <SEP> 70% <SEP> 73% <SEP> 77% <SEP> 80% <SEP> 88%
<tb> PIP / base <SEP> 30% <SEP> 70% <SEP> 70% <SEP> 60% <SEP> 100%
<tb> ACH / base <SEP> 40% <SEP> 15% <SEP> 0% <SEP> 30% <SEP> 0%
<tb> BM / base <SEP> 30% <SEP> 15% <SEP> 30% <SEP> 10% <SEP> 0%
<tb><SEP> PIP <SEP> N 1 <SEP> 21% <SEP> 51.1% <SEP> 53.9% <SEP> 48 <SEP>% <SEP> 0
<tb> PIP <SEP> N 2 <SEP> 0% <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 88 <SEP>%
<tb> ACH <SEP> 28% <SEP> 10.95% <SEP> 0 <SEP> 24 <SEP>% <SEP> 0
<tb> BM <SEP> N 2 <SEP> 21 <SEP>% <SEP> 10.95% <SEP> 0 <SEP> 0 <SEP> 0
<tb> BM <SEP> N 3 <SEP> 0 <SEP> 0 <SEP> 23.1% <SEP> 8 <SEP>% <SEP> 0
<tb> Ester <SEP> C <SEP> 10 <SEP>% <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 0
<tb> Ester <SEP> D <SEP> 0 <SEP> 10 <SEP>% <SEP> 0 <SEP> 0 <SEP> 0
<tb> Ester <SEP> B <SEP> 0 <SEP> 0 <SEP> 6.5% <SEP> 5 <SEP>% <SEP> 0
<tb> AV <SEP> N 1 <SEP> (1) <SEP> 15 <SEP>% <SEP> 13 <SEP>% <SEP> 0 <SEP> 0 <SEP> 10.5 <SEP>%
<tb> AV <SEP> n <SEP> 2 (2) <SEP> 0 <SEP> 0 <SEP> 13% <SEP> 13 <SEP>% <SEP> 0
<tb><SEP> AU <SEP> n 1 <SEP> 4.5% <SEP> 3.5 <SEP>% <SEP> 2% <SEP> 0 <SEP> 0
<tb> n 2 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 1.5 <SEP>% <SEP> 0
<tb> AO <SEP> N <SEP> 1 <SEP> 0.5% <SEP> 0.5 <SEP>% <SEP> 0 <SEP> 0 <SEP> 0
<tb> AO <SEP> N <SEP> 2 <SEP> 0 <SEP> 0 <SEP> 0 <SEP> 0.5 <SEP>% <SEP> 0
<tb> AO <SEP> N <SEP> 3 <SEP> 0 <SEP> 0 <SEP> 1 <SEP> 1 <SEP> 0.5 <SEP>%
<tb><SEP> Agent <SEP> anti- <SEP> 0 <SEP> 0 <SEP> 0.5% <SEP> 0 <SEP> 1 <SEP>%
<tb> rust
<tb> Color <SEP> 0 <SEP> 0 <SEP> 2ppm <SEP> 1ppm <SEP> 0
<tb> Viscosity <SEP> to <SEP> 98.9 C <SEP> 6.3 <SEP> 5.35 <SEP> 5.7 <SEP> 5.6 <SEP> 4.9
<tb><SEP>"<SEP> to <SEP> 50 C <SEP> 14.3 <SEP> 12.6 <SEP> 13.6 <SEP> 13.4 <SEP> 11.7
<tb><SEP>"<SEP> to <SEP> 37.8 C <SEP> 18.7 <SEP> 16.5 <SEP> 18.3 <SEP> 18 <SEP> 15.5
<tb><SEP>"<SEP> to <SEP> -40 C <SEP> 985 <SEP> 963 <SEP> 949 <SEP> 920 <SEP> 963
<tb> in <SEP> centistokes
<Tb>

Note
(1) substance known under the trade name "Viscoplex 7 70"
(2) substance known under the trade name "Plexol HF 855"
Of course, the invention is not limited to the embodiments described which have been given by way of example. In particular, it comprises all the means constituting technical equivalents of the means described, and their combinations, if they are executed according to its spirit and implemented in the context of the following claims.

Claims (9)

R E V E N D I C A T IO N S  1. Hydraulic fluid, characterized in that it contains a proportion of 70 to 50% of a base comprising at least 30% of one or more isoparaffinic polymers having a number of carbon atoms ranging from 12 to the residual percentage, ie 30 to 10% of said hydraulic fluid, being represented by one or more additives, especially the lubricating additives, the additives, the additives for improving the viscometric properties, the lubricity additives and antioxidant additives, the aforementioned isoparaffinic polymers being obtained by polymerization of one or more linear polyolefin having a carbon number of from 6 to 14 by means of a Friedel and Crafts type catalyst and by hydrogenation of the residual double bonds of the products resulting from this polymerization  2. Hydraulic fluid according to claim 1, characterized in that the &alpha; These olefins are prepared by telomerization of ethylene over a Ziegler catalyst.  3. Hydraulic fluid according to claim 1 or 2, characterized in that the abovementioned base also comprises an n-alkylcyclohexane, especially an n-allylcyclohexane whose n-alkyl chain comprises 10 to 14 carbon atoms.  4. Hydraulic fluid according to one of the preceding claims, characterized in that the above-mentioned base also comprises a mineral base, in particular a naphthenic base.  5. Hydraulic fluid according to one of the preceding claims, characterized in that it comprises a lubricant addltif consisting of a complex ester, that is to say an ester of which at least two of the constituent acid and alcohol is polyfunctional, including an ester neopolyol complex.  6. Hydraulic fluid according to one of claims 1 to 5, characterized in that the aforementioned base corresponds to the following composition, by weight  isoparaffinic polymer @ 30 to 100%, preferably  60 to 80%  n-alkylcyclohexane: 0 to 4, preferably 5 to 159; and  mineral base: 0 to 30%, preferably 15 to 25%.  7. Hydraulic fluid according to claim 6, characterized in that it corresponds to the following composition, by weight:  base: 70 to 90%, preferably 74 to 81.5%  - Neopolyol complex ester: 0 to 8%, preferably  5 to 7%  - additive improving the viscometric properties:  10 to 16, preferably 12 to 15%  - lubricity additive: 0 to 4%, preferably 1 to 3%  antioxidant additive: 0 to 2%, preferably 0.5 to 1%  8. Hydraulic fluid according to one of the preceding claims, characterized in that the aforementioned base comprises one or more isoparaffinic polymers having a number of carbon atoms ranging from 20 to 30.  9. Hydraulic fluid according to claim 8, characterized in that the aforementioned isoparaffin polymers comprise only one or more polymers having a number of carbon atoms of between 20 and 30.