LOW-VISCOSITY LUBRICATING POLYOLEFINS

Abstract

Disclosed is a low-viscosity oil including more than 50 wt % of 9-methyl-11-octyl-heneicosane as well as a lubricating composition including the base oil and optionally another base oil or an additive. The oil has a kinematic viscosity at 100 C., measured according to standard ASTM D445, ranging from 3 to 4 mm.sup.2/s.sup.1. Also disclosed is such a low-viscosity oil prepared according to a specific method using a metallocene catalyst as well as the use of the oil as a high-performance lubricant for lubrication in the fields of engines, gears, brakes, hydraulic fluids, coolants and greases.

Claims

1-18 (canceled)

19. Oil having kinematic viscosity at 100 C., measured according to standard ASTM D445, ranging from 3 to 4 mm.sup.2.s.sup.1, comprising more than 50 weight % of 1-decene trimer of formula (I) ##STR00003##

20. The oil according to claim 19 comprising 50 to 99 weight % of 1-decene trimer of formula (I), or 60 to 90 weight % of 1-decene trimer of formula (I), or 70 to 90 weight % of 1-decene trimer of formula (I).

21. The oil according to claim 19 comprising at least 65 weight % of 1-decene trimer of formula (I), or at least 70 weight % of 1-decene trimer of formula (I) , or at least 80 weight % of 1-decene trimer of formula (I), or at least 90 weight % of 1-decene trimer of formula (I).

22. The oil according to claim 19 also comprising at least one other saturated oligomer of 1-decene: selected from among the other trimers of 1-decene; or selected from among the dimers of 1-decene, the other trimers of 1-decene, the tetramers of 1-decene, the pentamers of 1-decene.

23. The oil according to claim 19 also comprising at least one other saturated oligomer of 1-decene selected from among 9-methyl-nonadecane and 9-methyl-11,13-dioctyl-tricosane.

24. The oil according to claim 19 comprising 51 to 99.9 weight % of 1-decene trimer of formula (I) and 0.1 to 49 weight % of at least one other saturated trimer of 1-decene.

25. The oil according to claim 19 comprising: 51 to 99.6 weight % of 1-decene trimer of formula (I); 0.1 to 1 weight % of at least one saturated dimer of 1-decene or of 9-methyl-nonadecane; 0.1 to 25 weight % of at least one other saturated trimer of 1-decene; 0.1 to 20 weight % of at least one saturated tetramer of 1-decene or of 9-methyl-11,13-dioctyl-tricosane; 0.1 to 1.5 weight % of at least one saturated pentamer of 1-decene.

26. The oil according to claim 19 wherein: (a) the kinematic viscosity at 100 C., measured according to standard ASTM D445, ranges from 3.2 to 3.8 mm.sup.2.s.sup.1 or is 3,5 mm.sup.2.s.sup.1; or wherein (b) the viscosity index is higher than 120, or is 130 or higher, or is between 120 and 140 or between 125 and 135; or wherein (c) the volatility measured according to standard ASTM D6375 is lower than 10.8% by mass or lower than 10.5% by mass; or wherein (d) the cold cranking viscosity (CCS) at 35 C., measured according to standard ASTM D5293, is lower than 900 mPa.Math.s or lower than 800 mPa.Math.s.

27. The oil according to claim 19 wherein: (a) the kinematic viscosity at 100 C., measured according to standard ASTM D445, ranges from 3.2 to 3.8 mm.sup.2.s.sup.1 or is 3,5 mm.sup.2.s.sup.1; and wherein (b) the viscosity index is higher than 120, or is 130 or higher, or is between 120 and 140 or between 125 and 135; and wherein (c) the volatility measured according to standard ASTM D6375 is lower than 10.8% by mass or lower than 10.5% by mass; and wherein (d) the cold cranking viscosity (CCS) at 35 C., measured according to standard ASTM D5293, is lower than 900 mPa.Math.s or lower than 800 mPa.Math.s.

28. The oil according to claim 19 comprising 1-decene trimer of formula (I), prepared using a method comprising: oligomerisation of 1-decene in the presence of hydrogen (H.sub.2), a metallocene catalyst and an activator compound, or in the presence of hydrogen (H.sub.2), a metallocene catalyst, an activator compound and a co-activator compound; catalytic hydrogenation of the oligomerisation products in the presence of hydrogen (H.sub.2) and a catalyst selected from among a hydrogenation catalyst and a palladium-containing hydrogenation catalyst; separation via distillation at reduced pressure of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I).

29. The oil according to claim 19 comprising 1-decene trimer of formula (I), prepared using a method comprising oligomerisation of 1-decene in the presence of hydrogen (H.sub.2), a metallocene catalyst and an activator compound, or in the presence of hydrogen (H.sub.2), a metallocene catalyst, an activator compound and a co-activator compound; catalytic hydrogenation of the oligomerisation products in the presence of hydrogen (H.sub.2) and a catalyst selected from among a hydrogenation catalyst and a palladium-containing hydrogenation catalyst; separation via distillation at reduced pressure of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I); also comprising: prior preparation of 1-decene via catalytic oligomerisation of ethylene; or deactivation of the catalyst after oligomerisation of 1-decene or after catalytic hydrogenation of the oligomerisation products; recycling of the dimer fraction of 1-decene (e.g. 9-methyl-nonadecane), separated by distillation at reduced pressure, and oligomerisation of this recycled dimer fraction of 1-decene with 1-decene, in the presence of hydrogen (H.sub.2), a metallocene catalyst and an activator compound, or in the presence of hydrogen (H.sub.2), a metallocene catalyst, an activator compound and a co-activator compound; or a final hydrogenation step of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I) in the presence of hydrogen (H.sub.2) and a catalyst selected from among a hydrogenation catalyst and palladium-containing hydrogenation catalyst.

30. The oil according to claim 19 comprising 1-decene trimer of formula (I) prepared using a method comprising: oligomerisation of 1-decene in the presence of hydrogen (H.sub.2), a metallocene catalyst and an activator compound, or in the presence of hydrogen (H.sub.2), a metallocene catalyst, an activator compound and a co-activator compound; catalytic hydrogenation of the oligomerisation products in the presence of hydrogen (H.sub.2) and a catalyst selected from among a hydrogenation catalyst and a palladium-containing hydrogenation catalyst; separation via distillation at reduced pressure of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I); wherein: oligomerisation of 1-decene is conducted over a time ranging from 2 to 300 min or from 5 to 180 min or from 30 to 140 min; or oligomerisation of 1-decene is conducted in the presence of hydrogen (H.sub.2) at partial pressure ranging from 0.1 to 20 bar or from 1 to 6 bar; or oligomerisation is performed with a hydrogen/1-decene weight ratio higher than 100 ppm or lower than 600 ppm or between 100 and 600 ppm; or oligomerisation of 1-decene is conducted at a temperature ranging from 50 to 200 C. or from 70 to 160 C. or from 80 to 150 C. or from 90 to 140 C. or from 100 to 130 C.; or the metallocene catalyst is a racemic compound of formula (II)
L (Q.sup.1) (Q.sup.2) MR.sup.1R.sup.2 (II) where: M is a transition metal selected from among titanium, zirconium, hafnium and vanadium, or it is zirconium; Q.sup.1 and Q.sup.2, substituted or unsubstituted, are independently a cyclic tetrahydroindenyl group or Q.sup.1 and Q.sup.2 are independently a cyclic tetrahydroindenyl group and are bonded to form a polycyclic structure; L is a Q.sup.1 and Q.sup.2 bridging C.sub.1-C.sub.20 divalent alkyl group or L is a group selected from among methylene (CH.sub.2), ethylene (CH.sub.2CH.sub.2), methylmethylene (CH(CH.sub.3)), 1-methyl-ethylene (CH(CH.sub.3)CH.sub.2), n-propylene (CH.sub.2CH.sub.2CH.sub.2), 2-methylpropylene (CH.sub.2CH(CH.sub.3)CH.sub.2), 3-methylpropylene (CH.sub.2CH.sub.2CH(CH.sub.3)), n-butylene CH.sub.2CH.sub.2CH.sub.2CH.sub.2), 2-methylbutylene (CH.sub.2CH(CH.sub.3)CH.sub.2CH.sub.2), 4-methylbutylene (CH.sub.2CH.sub.2CH.sub.2CH(CH.sub.3)), pentylene and isomers thereof, hexylene and isomers thereof, heptylene and isomers thereof, octylene and isomers thereof, nonylene and isomers thereof, decylene and isomers thereof, undecylene and isomers thereof, dodecylene and isomers thereof; R.sup.1 and R.sup.2, substituted or unsubstituted are independently an atom or a group selected among hydrogen, halogens (such as Cl and I), alkyl (such as Me, Et, nPr, iPr), alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, silylalkyl, silylalkenyls, silylalkynyls, germylalkyl, germylalkenyl, germylalkynyl; or R.sup.1 et R.sup.2 together with M form a metallocycle having 3 to 20 carbon atoms; or the metallocene catalyst is selected from among rac-ethylene bis(tetrahydroindenyl) zirconium dimethyl and rac-ethylene bis(tetrahydroindenyl)zirconium dichloride; or oligomerisation of 1-decene is performed in a solvent selected from among a straight-chain or branched hydrocarbon, cyclic or noncyclic hydrocarbon, an aromatic alkylated compound and mixtures thereof, or in a solvent selected from among butanes, pentanes, hexanes, heptanes, octanes, cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, methylcycloheptane, toluene, xylene and mixtures thereof; or the activator compound is selected from among an ionic activator and an oligomeric compound comprising residues of formula Al(R)O where R is independently a cyclic or straight-chain C.sub.1-C.sub.20 alkyl group; or the activator compound is selected from among methylalumoxane, methylalumoxane modify, ethylalumoxane, isobutylalumoxane and mixtures thereof; or the activator compound is selected from among dimethylanilinium tetrakis(perfluorophenyl)borate (DMAB), triphenylcarbonium tetrakis(perfluorophenyl)borate, dimethylanilinium tetrakis(perfluorophenyl)aluminate and mixtures thereof; or the co-activator compound is a trialkylaluminium derivative or a compound selected from among tri-ethyl aluminium (TEAL), tri-iso-butyl aluminium (TIBAL), tri-methyl aluminium (TMA), tri-n-octyl aluminium and methyl-methyl-ethyl aluminium (MMEAL); or deactivation of the catalyst is obtained via action of air or water or using at least one alcohol or solution of deactivating agent; or the pressure of hydrogen (H.sub.2) for catalytic hydrogenation of the oligomerisation products ranges from 5 to 50 bar or from 10 to 40 bar or from 15 to 25 bar; or the hydrogenation catalyst is selected from among a palladium derivative, supported palladium derivative, a derivative of alumina-supported palladium (e.g. on gamma-alumina), a nickel derivative, a derivative of supported nickel, a derivative of kieselguhr-supported nickel, a platinum derivative, derivative of supported platinum, cobalt-molybdenum derivative, derivative of supported cobalt-molybdenum; or the pressure of hydrogen (H.sub.2) for final hydrogenation of the majority fraction by weight of 1-decene trimer of formula (I) ranges from 5 to 50 bar or from 10 to 40 bar or from 15 to 25 bar; or the hydrogenation time for final hydrogenation is between 2 and 600 min or between 30 and 300 min; or final hydrogenation finale is conducted at a temperature ranging from 50 to 200 C. or from 60 to 150 C. or from 70 to 140 C. or from 80 to 120 C.; or the hydrogenation catalyst, for final hydrogenation of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I), is selected from among a palladium derivative, derivative of supported palladium, derivative of alumina-supported palladium (e.g. on gamma-alumina), a nickel derivative, a derivative of supported nickel, a derivative of kieselguhr-supported nickel, a platinum derivative, supported platinum derivative, cobalt-molybdenum derivative, supported cobalt-molybdenum derivative.

31. The oil according to claim 19 comprising 1-decene trimer of formula (I) prepared using a method comprising: oligomerisation of 1-decene in the presence of hydrogen (H.sub.2), a metallocene catalyst and an activator compound, or in the presence of hydrogen (H.sub.2), a metallocene catalyst, an activator compound and a co-activator compound; catalytic hydrogenation of the oligomerisation products in the presence of hydrogen (H.sub.2) and a catalyst selected from among a hydrogenation catalyst and a palladium-containing hydrogenation catalyst; separation via distillation at reduced pressure of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I); wherein: oligomerisation of 1-decene is conducted over a time ranging from 2 to 300 min, or from 5 to 180 min or from 30 to 140 min; oligomerisation of 1-decene is performed in the presence of hydrogen (H.sub.2) at partial pressure ranging from 0.1 to 20 bar or from 1 to 6 bar; oligomerisation of 1-decene is performed with a hydrogen/1-decene weight ratio higher than 100 ppm or lower than 600 ppm or between 100 and 600 ppm; or oligomerisation of 1-decene is conducted at a temperature ranging from 50 to 200 C., or from 70 to 160 C., or from 80 to 150 C., or from 90 to 140 C. or from 100 to 130 C.; the metallocene catalyst is a racemic compound of formula (II).
L(Q.sup.1) (Q.sup.2)MR.sup.1R.sup.2 (II) where: M is a transition metal selected from among titanium, zirconium, hafnium and vanadium, or it is zirconium; Q.sup.1 and Q.sup.2, substituted or unsubstituted are independently a cyclic tetrahydroindenyl group or Q.sup.1 and Q.sup.2 are independently a cyclic tetrahydroindenyl group and are bonded to form a polycyclic structure; L is a Q.sup.1 and Q.sup.2 bridging C.sub.1-C.sub.20 divalent alkyl group, or L is a group selected from among methylene (CH.sub.2), ethylene (CH.sub.2CH.sub.2), methylmethylene (CH(CH.sub.3)), 1-methyl-ethylene (CH(CH.sub.3)CH.sub.2), n-propylene (CH.sub.2CH.sub.2CH.sub.2), 2-methylpropylene (CH.sub.2CH(CH.sub.3)CH.sub.2), 3-methylpropylene (CH.sub.2CH.sub.2CH(CH.sub.3)), n-butylene (CH.sub.2CH.sub.2CH.sub.2CH.sub.2), 2-methylbutylene (CH.sub.2CH(CH.sub.3)CH.sub.2CH.sub.2), 4-methylbutylene (CH.sub.2CH.sub.2CH.sub.2CH(CH.sub.3)), pentylene and isomers thereof, hexylene and isomers thereof, heptylene and isomers thereof, octylene and isomers thereof, nonylene and isomers thereof, decylene and isomers thereof, undecylene and isomers thereof, dodecylene and isomers thereof; R.sup.1 and R.sup.2, substituted or unsubstituted are independently an atom or group selected from among hydrogen, halogens (such as Cl and I), alkyl (such as Me, Et, nPr, iPr), alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, silylalkyl, silylalkenyls, silylalkynyls, germylalkyl, germylalkenyl, germylalkynyl; or R.sup.1 and R.sup.2 together with M form a metallocycle having 3 to 20 carbon atoms; or the metallocene catalyst is selected from among rac-ethylene bis(tetrahydroindenyl) zirconium dimethyl and rac-ethylene bis(tetrahydroindenyl)zirconium dichloride; oligomerisation of 1-decene is performed in a solvent selected from among a straight-chain or branched hydrocarbon, cyclic or non-cyclic hydrocarbon, an aromatic alkylated compound and mixtures thereof, or in a solvent selected from among butanes, pentanes, hexanes, heptanes, octanes, cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, methylcycloheptane, toluene, xylene and mixtures thereof; the activator compound is selected from among an ionic activator and oligomeric compound comprising residues of formula Al(R)O where R is independently a cyclic or straight-chain C.sub.1-C.sub.20 alkyl group; or the activator compound is selected from among methylalumoxane, modified methylalumoxane, ethylalumoxane, isobutylalumoxane and mixtures thereof; or the activator compound is selected from among dimethylanilinium tetrakis(perfluorophenyl)borate, triphenylcarbonium tetrakis(perfluorophenyl)borate, dimethylanilinium tetrakis(perfluorophenyl)aluminate and mixtures thereof; the co-activator compound is a trialkylaluminium derivative or a compound selected from among tri-ethyl aluminium (TEAL), tri-iso-butyl aluminium (TIBAL), tri-methyl aluminium (TMA), tri-n-octyl aluminium and methyl-methyl-ethyl aluminium (MMEAL); deactivation of the catalyst is obtained via action of air or water or using at least one alcohol or a solution of deactivating agent; or the pressure of hydrogen (H.sub.2) for catalytic hydrogenation of the oligomerisation products ranges from 5 to 50 bar, or from 10 to 40 bar or from 15 to 25 bar; the hydrogenation catalyst is selected from among a palladium derivative, derivative of supported palladium, derivative of alumina-supported palladium (e.g. on gamma-alumina), a nickel derivative, derivative of supported nickel, derivative of kieselguhr-supported nickel, a platinum derivative, derivative of supported platinum, cobalt-molybdenum derivative, supported cobalt-molybdenum derivative; the pressure of hydrogen (H.sub.2) for final hydrogenation of the majority fraction by weight of 1-decene trimer of formula (I) ranges from 5 to 50 bar, or from 10 to 40 bar or from 15 to 25 bar; the hydrogenation time for final hydrogenation is between 2 and 600 min or between 30 and 300 min; final hydrogenation is conducted at a temperature ranging from 50 to 200 C., or from 60 a 150 C., or from 70 to 140 C. or from 80 to 120 C.; the hydrogenation catalyst, for final hydrogenation of the trimer fraction comprising more than 50 weight % of 1-decene trimer of formula (I), is selected from among a palladium derivative, a derivative of supported palladium, derivative of alumina-supported palladium (e.g. on gamma-alumina), a nickel derivative, supported nickel derivative, kieselguhr-supported nickel derivative, a platinum derivative, supported platinum derivative, cobalt-molybdenum derivative, supported cobalt-molybdenum derivative.

32. A base oil comprising the oil according to claim 19.

33. A method to improve the Fuel Eco (FE) of a lubricant, or to reduce the fuel consumption of an engine or to reduce the fuel consumption of a vehicle engine, comprising applying an effective amount of the oil of claim 19.

34. A lubricating composition comprising: at least one base oil selected from among an oil according to claim 19; or at least one base oil selected from among an oil according to claim 19 and at least one other base oil; or at least one base oil selected from among an oil according to claim 19 and at least one additive; or at least one base oil selected from among an oil according to claim 19, at least one other base oil and at least one additive.

35. The lubricating composition according to claim 34 comprising at least 10 weight % of the at least one base oil.

36. A method to improve the Fuel Eco (FE) of a lubricant, or to reduce the fuel consumption of an engine or to reduce the fuel consumption of a vehicle engine, comprising applying an effective amount of the lubricating composition according to claim 34.

37. The lubricating composition according to claim 34 comprising at least 20 weight % of the at least one base oil.

38. The lubricating composition according to claim 34 comprising at least 30 weight % of the at least one base oil.

Description

EXAMPLES

[0179] An autoclave reactor is used equipped with an agitator and a system controlling temperature and the feeding of nitrogen, hydrogen and 1-decene.

[0180] 1-decene (produced by TCI or Acros) is used at purity higher than 94%. It is purified on 3 and 13 molecular sieves (Sigma-Aldrich). Before use, the molecular sieves are previously dried at 200 C. for 16 hours.

[0181] The products are characterized by .sup.1H NMR and two-dimensional gas chromatography (GCGC).

[0182] For NMR, the PAO samples are diluted in deuterated chloroform and the NMR spectra are performed at 300 K on Bruker 400 MHz spectrometers: .sup.1H, .sup.13C, HMQC (heteronuclear multiple quantum coherence) and HMBC (heteronuclear multiple bond coherence).

[0183] Two-dimensional chromatography is implemented in continuous mode and using two columns, apolar and polar. The entirety of the effluent derived from the first column is separated in the second dimension. Separation of the compounds is governed by volatility on the first column and by specific interactions (of type -, dipolar interactions etc.) on the second dimension. As a function of their viscosity, the samples are generally diluted twice in heptane. Chromatographic conditions were optimised in order to be able to elute the PAOs preparing according to the invention. The samples were analysed under GCGC with cryogenic modulation (liquid nitrogen), programming of the first oven from 45 C. (5 min) up to 320 C. (20 min) with a ramp of 3 C/min, programming of the secondary oven from 60 C. (5 min) up to 330 C. (20 min) with a ramp of 3 C/min, and columns used under the following operating conditions: [0184] 1.sup.st dimension: HP1, 25 m, ID 0.32 mm, film thickness: 0.17 m, [0185] 2.sup.and dimension: BPX-50, 1.5 m, ID 0.1 mm, film thickness: 0.1 m, [0186] injector: split 100: 1, injected volume: 0.1 l; [0187] detector: FID, 320 C.; [0188] hot jet temperature: 320 C.; [0189] cold jet programming from 80 to 5%; [0190] modulation period: 4.8 s.

Example 1

[0191] An 8 L autoclave reactor was used. Before use, the autoclave reactor was dried at 130 C. under a stream of nitrogen for one hour then cooled to 110 C. It was then filled with 3 500 mL of 1-decene under a stream of nitrogen. The temperature of the reactor was held at 110 C. and hydrogen (H.sub.2) was fed at a m/m ratio of H.sub.2/1-decene of 414 ppm.

[0192] The catalyst was rac-ethylene bis(tetrahydroindenyl) zirconium dimethyl activated with dimethylanilinium tetrakis(perfluorophenyl)borate (DMAB) in a B/Zr molar ratio of 1.75. Triisobutyl aluminium (TiBAI) was used as co-activator compound with Al/Zr molar ratio of 200. It allows trapping of impurities contained in the reactor.

[0193] Oligomerisation started to occur as soon as the activated catalyst was added in a concentration of 17 M relative to the oligomerisation solution.

[0194] After 120 min, 5 mL of isopropanol were added to deactivate the catalyst. Hydrogenation of the reaction products was then carried out using an alumina-supported palladium catalyst (5 g of palladium on gamma-alumina at 5% m/m relative to the alumina product by Alfa Aesar) and hydrogen (H.sub.2) at 20 bar, at a temperature of 100 C., for 240 min.

[0195] The oligomerisation products and the trimer fraction comprising more than 50 weight % of 9-methyl-11-octyl-henicosane were then separated by distillation at reduced pressure (0.67 mBar or 0.5 mmHg) in two steps first in accordance with standard ASTM D2892 and then with standard ASTM D5236 (1) using a column with 15 theoretical plates and maximum temperature of 375 C., then (2) using a column with 2 theoretical plates and vapour temperature at the head of the column ranging from 375 to 445 C.

[0196] Distillation following standard ASTM D2892 allows the separation of products having a boiling point lower than 375 C. Distillation following standard ASTM D5236 allows isolation of the products having a boiling point ranging from 375 to 445 C. The content of 9-methyl-11-octyl-henicosane in the oil of the invention is 71.4%.

[0197] This oil of the invention comprising more than 50 weight % of 9-methyl-11-octyl-henicosane has kinematic viscosity at 100 C., measured according to standard ASTM D445, of 3.448 mm.sup.2.s.sup.1. The viscosity index of this oil is 130. Its volatility, measured according to standard ASTM D6375 is 10.3% by mass and its cold cranking viscosity (CCS) at 35 C., measured according to standard ASTM D5293, is 780 mPa.Math.s. Its mean molecular mass is 372 g/mol.

[0198] The characteristics of the oil of the invention allow excellent lubricating, rheological and oxidation resistance properties to be obtained as well as Fuel Eco.

Example 2

[0199] Procedure was the same as for Example 1 for oligomerisation of 1-decene.

[0200] The oligomerisation products and trimer fraction comprising more than 50 weight % of 9-methyl-11-octyl-henicosane were then separated by distillation at reduced pressure (0.67 mBar or 0.5 mmHg) in two steps, first according to standard ASTM D2892 and then according to standard ASTM D5236 : (1) using a column with 15 theoretical plates and maximum temperature of 375 C., then (2) using a column with 2 theoretical plates and vapour temperature at the head of the column ranging from 445 to 465 C.

[0201] Distillation according to standard ASTM D2892 allows the separation of products having a boiling point lower than 375 C. Distillation according to standard ASTM D5236 allows isolation of the products having a boiling point ranging from 445 to 465 C.

[0202] The oil of the invention obtained has a 9-methyl-11-octyl-henicosane content of 65.7%.

[0203] This oil of the invention comprising more than 50 weight % of 9-methyl-11-octyl-henicosane has kinematic viscosity at 100 C., measured according to standard ASTM D445, of 3.640 mm.sup.2.s.sup.-1. The viscosity index of this oil is 132. Its volatility measured according to standard ASTM D6375 is 9.1% by mass and its cold cranking viscosity (CCS) at -35 C., measured according to standard ASTM D5293, is 890 mPa.Math.s. Its mean molecular mass is 383 g/mol.

[0204] Again, the characteristics of this oil of the invention allow excellent lubricating, rheological and oxidation resistance properties to be obtained, as well as Fuel Eco.

Example 3

[0205] Procedure was the same as for Example 1 to prepare a first oil fraction of the invention. Procedure was the same as in Example 2 to prepare a second oil fraction of the invention. The two fractions were then assembled together.

[0206] Final hydrogenation was then carried out using a palladium catalyst (0.5% m/m relative to H.sub.2) supported on alumina (5 g of palladium on gamma-alumina at 5% m/m relative to the alumina product by Alfa Aesar) and hydrogen (H.sub.2) at 20 bar, at a temperature of 90 C., for 240 min.

[0207] The oil of the invention obtained has a 9-methyl-11-octyl-henicosane content of 74.7%.

[0208] This oil of the invention comprising more than 50 weight % of 9-methyl-11-octyl-henicosane has kinematic viscosity at 100 C., measured according to standard ASTM D445, of 3.569 mm.sup.2.s.sup.1. The viscosity index of this oil is 130. Its volatility measured according to standard ASTM D6375 is 10.3% by mass and its cold cranking viscosity (CCS) at 35 C., measured according to standard ASTM D5293, is 720 mPa.Math.s. Its mean molecular mass is 378 g/mol.

[0209] Again, the characteristics of the oil of the invention allow excellent lubricating, rheological and oxidation resistance properties to be obtained, as well as Fuel Eco.

Comparative Example 1

[0210] Identical measurements and characterizations were carried out using a reference commercial oil. This was a PAO oil (produced by ExxonMobil Spectrasyn Plus 3.6) prepared from olefins via acid catalysis.

[0211] This reference PAO oil has kinematic viscosity at 100 C., measured according to standard ASTM D445, of 3.671 mm.sup.2.s.sup.1. It has a viscosity index is 118. Its volatility measured according to standard ASTM D6375 is 14.3% by mass and its cold cranking viscosity (CCS) at 35 C., measured according to standard ASTM D5293 is 1100 mPa.Math.s. Its mean molecular mass is 374 g/mol.

[0212] Also, the specifications of this commercial oil are the following: kinematic viscosity at 100 C., measured according to standard ASTM D445, of 3.5 to 3.9 mm.sup.2.s.sup.1; volatility measured according to standard ASTM D5800 lower than 17% by mass.

[0213] The method of the invention therefore allows the preparation of an oil having properties that are equivalent to or better than those of commercial PAO oils, in particular the viscosity index or cold cranking viscosity of the oils of the invention have much higher ratings.