Lubricant composition

Abstract

Disclosed is a lubricant composition including: at least one base oil; at least one polyalkylene glycol with at least 50% by weight of butylene oxide units and having a kinematic viscosity, measured at 100° C. according to standard ASTM D445 (2015), which is greater than or equal to 50 mm2/s, a kinematic viscosity, measured at 40° C. according to standard ASTM D445 (2015), which is greater than or equal to 1000 mm2/s and a Viscosity Index, measured according to standard ASTM D2270 (2012), which is greater than or equal to 180. Also disclosed is the use of such a composition for transmission or gear lubrication.

Claims

1. Method for reducing traction coefficient comprising lubricating at least one mechanical part of a transmission member of motor vehicles or industrial gears with at least one lubricant composition comprising: at least one base oil; at least one polyalkylene glycol (PAG) comprising at least 50% by weight of butylene oxide units and having a kinematic viscosity measured at 100° C. according to ASTM D445 (2015) greater than or equal to 50 mm.sup.2/s, a kinematic viscosity measured at 40° C. according to ASTM D445 (2015) greater than or equal to 1000 mm.sup.2/s, and a viscosity index measured according to ASTM D2270 (2012) greater than or equal to 180, wherein the PAG is obtained by reaction with butylene oxides of one or more polyols comprising 2 to 12 carbon atoms, and wherein the PAG comprises an O/C ratio (oxygen atom/carbon atom) weight/weight between 0.29 and 0.38.

2. The method according to claim 1, wherein the PAG comprises from 25 to 300 moles of butylene oxide units.

3. The method according to claim 1, wherein the PAG comprises at least 80% by weight of butylene oxide units.

4. The method according to claim 1, wherein the alkylene oxide units of PAG are solely butylene oxide units.

5. The method according to claim 1, wherein the PAG has a kinematic viscosity measured at 100° C. according to ASTM D445 (2015) between 50 and 500 mm.sup.2/s, a kinematic viscosity measured at 40° C. according to ASTM D445 (2015) of between 1000 and 4500 mm.sup.2/s, and a viscosity index measured according to ASTM D2270 (2012) between 180 and 300.

6. The method according to claim 1, wherein the lubricating composition comprises at most 30% by weight of PAG.

7. The method according to claim 1, wherein the base oil is selected from Group II oils and Group III oils.

8. The method according to claim 1, wherein the PAG comprises from 50 to 200 moles of butylene oxide units.

9. The method according to claim 1, wherein the PAG comprises an O/C ratio (oxygen atom/carbon atom) by weight/mol between 0.29 and 0.35.

10. The method according to claim 1, wherein the lubricating composition comprises from 6% to 30% by weight of PAG.

11. The method according to claim 1, wherein the lubricating composition comprises from 9% to 16% by weight of PAG.

12. The method according to claim 1, wherein the PAG is obtained by reaction with butylene oxides of diol.

Description

EXAMPLES

(1) Description of the PAG according to the invention implemented in the examples:

(2) TABLE-US-00002 TABLE 1 Kinematic viscosity Kinematic viscosity Viscosity index measured at 100° C. measured at 40° C. measured according to ASTM according to ASTM according to D445 (2015) D445 (2015) (2015) ASTM D2270 (mm.sup.2/s) (mm.sup.2/s) (2012) PAG1 130 1140 221 PAG2 127 1130 219 PAG3 437 4230 279

(3) Lubricant Compositions According to the Invention:

(4) The lubricant compositions were formulated with PAG of the invention in order to have a kinematic viscosity at 100° C. of about 7.5 mm.sup.2/s, wherein these compositions are described in Table 2 below.

(5) TABLE-US-00003 TABLE 2 CL1 CL2 CL3 (% weight) (% weight) (% weight) Base oil (mixture of 71.97 76.91 77.27 a Group III base oil with a kinematic viscosity at 40° C. equal to 12 mm.sup.2/s and a Group III base oil with a kinematic viscosity at 40° C. equal to 19 mm.sup.2/s) PAG1 — 14.54 — PAG2 — — 14.18 Additives 8.55 8.55 8.55 Viscosity at 100° C. 7.57 7.56 7.59 (mm.sup.2/s) according to ASTM D445 (2015) Viscosity at 40° C. 37.7 36.5 36.6 (mm.sup.2/s) according to ASTM D445 (2015) Viscosity index 174 182 183 according to ASTM D2270 (2012)

(6) Comparative Lubricant Compositions:

(7) The following comparative compositions were formulated to have a kinematic viscosity at 100° C. of about 7.5 mm.sup.2/s, wherein these compositions are described in Table 3 below. The base oil and additives are identical to those of compositions CL2 and CL3.

(8) TABLE-US-00004 TABLE 3 CC1 CC2 (% weight) (% weight) Base oil 80.45 74.84 Ethylene/propylene 5 copolymer PAMA (Viscoplex 0-130 ®) 6 PAMA (Viscobase 11-522 ®) 16.61 Additives 8.55 8.55 Viscosity at 100° C. 7.4 7.6 (mm.sup.2/s) according to ASTM D445 (2015) Viscosity at 40° C. 35 38.2 (mm.sup.2/s) according to ASTM D445 (2015) Viscosity index 183 172 according to ASTM D2270 (2012)

(9) Evaluation of Performances of Compositions

(10) The performances of the lubricant compositions CL2, CL3, CC1 and CC2 were determined according to the following methods: Cold properties by Brookfield measurement at −40° C. according to ASTM D2983 (2015), Wear according to ISO14635-3 (2005), The shear stability determined by the loss of viscosity of the lubricant composition after a shearing process KRL 20 h according to the standard CEC-L-45-A-99 (2014), The thermo-oxidative stability measured by DKA according to the standard CEC L-48-A-00 (2014), The viscosity index according to ISO2909 (2014).

(11) TABLE-US-00005 TABLE 4 Thermo-oxidative stability Shear DKA Viscosity Cold stability Viscosity Viscosity index properties Wear KRL 20 h variation variation according Brookfield FZG Viscosity (40° C.) (100° C.) PAI (Peak to ASTM (−40° C.) 6 Loss mm.sup.2/s mm.sup.2/s Area D2270 mPa .Math. s level (%) (%) (%) Increase) CL2 182 23300 10 3 17 8 75 CL3 183 22900 8 3.1 8 7 80 CC1 183 40000 10 7 15 14 46 CC2 172 16700 7 4.5 14 12 82

(12) It appears that the viscosity temperature (VI) dependence is improved with respect to the CC2 reference for PAG of sufficient viscosity.

(13) These results also show that the compositions according to the invention have a good Brookfield viscosity, which is improved with respect to the CC1 reference.

(14) The shear stability is excellent. It can be seen that the solution of the invention, although more viscous, shears less than the Viscobase 11-522® during this test, despite the fact that the PAG tested are more viscous than the Viscobase 11-522®.

(15) Evaluation of the Traction Coefficients Under Different Conditions

(16) In order to evaluate the fuel economy potential of our solution, lubricant compositions with different viscosity index improvers were prepared and are described in Table 5 below. These compositions were made in order to have a similar kinematic viscosity at 100° C.

(17) The base oil and the additives are identical to those of the above compositions.

(18) TABLE-US-00006 TABLE 5 CC3 CL4 CL5 Base oils 76.95 78.37 83.5 Additives 7.25 7.25 7.25 Viscoplex Polymer 0-130 ® 14.5 PAG 1 14.38 PAG 3 9.25

(19) The traction coefficient (TC) was measured using the PCS Instruments' MTM tribometer. The measurement conditions were 75N load and the disk speed was 1 m/s at an evaluated temperature (40° C.) and an SRR of 20%. The results are shown in Table 6 below.

(20) TABLE-US-00007 TABLE 6 CC3 CL4 CL5 Viscosity at 100° C. 7.61 7.50 7.30 (mm.sup.2/s) according to ASTM D445 Viscosity index 204 186 194 according to ASTM D2270 TC (40° C., 20% SRR) 0.0516 0.0501 0.0493

(21) Thus, the lubricant compositions according to the invention CL4 and CL5 make it possible to lower the traction coefficient, wherein the reproducibility of the test is of the order of 3%.

(22) This reduction in the traction coefficient is particularly interesting in that it leads to an increase in the fuel economy.

(23) Evaluation of the Fuel Savings Eco

(24) The composition CL6 and the comparative composition CC4 below were used for this evaluation.

(25) TABLE-US-00008 Composition CL6 CC4 Composition CL6 AC4 base oil (mixture of a Group 86.2 85.6 III base oil with a kinematic viscosity at 40° C. equal to 12 mm.sup.2/s and a Group III base oil with a kinematic viscosity at 40° C. equal to 19 mm.sup.2/s) Viscoplex Polymer 3-200 ® 0 3.3 PAG 4 2.7 0 Friction modifier 0.7 0.7 Package of additive 1 10.4 10.4 Viscosity at 100° C. (mm.sup.2/s) according to ASTM 4.13 4.83 D445 Viscosity at 40° C. (mm.sup.2/s) according to ASTM D445 17.47 17.86 Viscosity index according to ASTM D2270 144 214 The friction modifier is a conventional organomolybdenum compound commercially available from Adeka under the trade name “Sakuralube®”, The conventional additive package 1 comprises a dispersant, detergents and an anti-wear additive.

(26) The test procedure is as follows:

(27) Characterization of the Compositions According to the Invention and Comparative in Terms of Fuel Economy.

(28) The test is carried out using a Honda L13-B engine, whose power is 81 kW at 5,500 rpm, driven by an electric generator imposing a rotation speed of between 650 and 5,000 rpm, while a torque sensor can measure the friction torque generated by the movement of the parts in the engine. The friction torque induced by the test lubricant is compared for each speed and each temperature of the torque induced by the reference lubricant composition (SAE 0W8), in this case CC4.

(29) The conditions of this test are as follows.

(30) The tests are carried out according to the following sequence: rinsing the engine with a rinsing oil comprising detergent additives, followed by rinsing with a reference lubricant composition; measuring the friction torque on the engine using the reference lubricant composition at the four different temperatures indicated below; rinsing the engine with a rinsing oil comprising detergent additives, followed by rinsing with a lubricant composition to be evaluated; measuring the friction torque on the engine using the lubricant composition to be evaluated at four different temperatures; rinsing the engine with a rinsing oil comprising detergent additives, followed by rinsing with the reference lubricant composition; and measuring the friction torque on the engine using the reference lubricant composition at the four different temperatures indicated below.

(31) The speed ranges, the variation of the speed as well as the temperature were chosen to cover, in the most representative way possible, the points of the NEDC certified cycle.

(32) The instructions implemented are a follows: Engine outlet water temperature: 35° C./50° C./80° C./90° C.±0.5° C., Oil temperature ramp: 35° C./50° C./80° C./90° C.±0.5° C.

(33) The friction gain is evaluated for each lubricant composition (CL) as a function of engine temperature and speed and in comparison with the friction of the reference lubricant composition.

(34) The results of the fuel economy test are summarized in the following table, and indicate the percentage averages of the friction gains for each composition at a given temperature over a speed range of 650 rpm to 5,000 rpm. with respect to the fuel economy results obtained with the reference composition CC4:

(35) TABLE-US-00009 Average percentage friction gain at a temperature T of the lubricating composition CL6 T = 35° C. 0.29% T = 50° C. 0.92% T = 80° C. 1.33% T = 90° C. 1.71%

(36) These results demonstrate that the friction gains for the CL6 composition according to the invention are much greater than the friction gains obtained with the reference composition CC4.

(37) It is to be understood that the greater the friction gains, the greater is the fuel economy. This therefore implies that the compositions according to the invention make it possible to increase the fuel economy in contrast to the compositions comprising no PAG according to the invention.