LUBRICATING COMPOSITION COMPRISING A DIESTER

Abstract

Lubricating compositions for motor vehicles are disclosed. The lubricating composition is of grade according to the SAE J300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5; and Y represents an integer ranging from 4 to 20; and comprises at least one diester of formula R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b (I). The composition may be used as a lubricant for an engine, in particular a vehicle engine, to reduce the fuel consumption of the engine and to improve engine cleanliness

Claims

1. A lubricating composition of grade according to the SAE J300 classification defined by formula (X)W(Y), wherein X represents 0 or 5; and Y represents an integer ranging from 4 to 20; said composition comprising at least one diester of formula (I):
R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b   (I) wherein: R independently represent a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s is 1, 2, 3, 4, 5 or 6; n is 1, 2 or 3; it being understood that, when s is different from 1, n may be the same or different; and R.sup.a and R.sup.b, which may be identical or different, independently represent saturated or unsaturated, linear or branched hydrocarbon groups having a linear chain of 6 to 18 carbon atoms; provided that, when s is 2 and n, which are identical, are 2, at least one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and provided that, when s is 1 and n is 3, at least one of the groups R bonded to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

2. The composition as claimed in claim 1, wherein R.sup.a and R.sup.b, which may be identical or different, have a linear sequence of 7 to 14 carbon atoms.

3. The composition as claimed in claim 1, wherein R.sup.a and R.sup.b, which may be identical or different, represent C.sub.6 to C.sub.18 linear alkyl groups.

4. The composition as claimed in claim 1, wherein R.sup.a and R.sup.b both represent n-octyl or n-undecyl groups.

5. The composition as claimed in claim 1, wherein the diester is of the following formula (I′)
R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O)—([C(R′).sub.2].sub.m—O).sub.s-1—C(O)—R.sup.b   (I′) wherein: R and R′ independently represent a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s is 1, 2 or 3; n is 2; m is 2; R.sup.a and R.sup.b, which may be identical or different, independently represent saturated or unsaturated, linear or branched hydrocarbon groups having a linear chain of 6 to 18 carbon atoms; provided that, when s is 2, at least one of the groups R or R′ represents a linear or branched (C.sub.1-C.sub.5)alkyl group.

6. The composition as claimed in claim 5, wherein the diester is of formula (I′) wherein: s is 2, one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and one of the groups R′ represents a linear or branched (C.sub.1-C.sub.5)alkyl group; the other groups R and R′ representing hydrogen atoms.

7. The composition as claimed in claim 5, wherein: s is equal to 1; one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group, the others representing hydrogen atoms.

8. The composition as claimed in claim 1, wherein the diester is obtained by esterification reaction between a monopropylene or polypropylene glycol; and one or more carboxylic acids R.sup.a—COOH and R.sup.b—COOH.

9. The composition as claimed in claim 1, said composition comprising from 1 to 30 wt % diester(s) of formula (I) based on the total weight of the composition.

10. The composition as claimed in claim 1, said composition comprising one or more base oils selected from the oils of Groups II, III and IV of the API.

11. The composition as claimed in claim 1, comprising one or more additives selected from friction modifying additives, anti-wear additives, extreme pressure additives, detergent additives, antioxidant additives, viscosity index improvers, pour point depressants, dispersing agents, antifoam agents, thickeners, and mixtures thereof.

12. The composition as claimed in claim 1, comprising at least one friction-modifying additive.

13. The composition as claimed in claim 1, of grade according to the SAE J300 classification selected from 0W4, 0W8, 0W12, 0W16, 0W20, 5W4, 5W8, 5W12, 5W16 and 5W20.

14. (canceled)

15. (canceled)

16. (canceled)

17. A method for lubricating an engine using a lubricating composition of grade according to the SAE J300 classification defined by formula (X)W(Y), wherein X represents 0 or 5; and Y represents an integer ranging from 4 to 20; said composition comprising at least one diester of formula (I):
R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b   (I) wherein: R independently represent a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s is 1, 2, 3, 4, 5 or 6; n is 1, 2 or 3; it being understood that, when s is different from 1, n may be the same or different; and R.sup.a and R.sup.b, which may be identical or different, independently represent saturated or unsaturated, linear or branched hydrocarbon groups having a linear chain of 6 to 18 carbon atoms; provided that, when s is 2 and n, which are identical, are 2, at least one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and provided that, when s is 1 and n is 3, at least one of the groups R bonded to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

18. A method for reducing the fuel consumption of the engine, using a lubricating composition of grade according to the SAE J300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5, and Y represents an integer ranging from 4 to 20 and dedicated to an engine, comprising as additive a diester of formula (I)
R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b   (I) wherein: R independently represent a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s is 1, 2, 3, 4, 5 or 6; n is 1, 2 or 3; it being understood that, when s is different from 1, n may be the same or different; and R.sup.a and R.sup.b, which may be identical or different, independently represent saturated or unsaturated, linear or branched hydrocarbon groups having a linear chain of 6 to 18 carbon atoms; provided that, when s is 2 and n, which are identical, are 2, at least one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and provided that, when s is 1 and n is 3, at least one of the groups R bonded to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

19. A method for improving engine cleanliness, using a lubricating composition of grade according to the SAE J300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5, and Y represents an integer ranging from 4 to 20, and dedicated to an engine, comprising as additive a diester of formula (I)
R.sup.a—C(O)—O—([C(R).sub.2].sub.n—O).sub.s—C(O)—R.sup.b   (I) wherein: R independently represent a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s is 1, 2, 3, 4, 5 or 6; n is 1, 2 or 3; it being understood that, when s is different from 1, n may be the same or different; and R.sup.a and R.sup.b, which may be identical or different, independently represent saturated or unsaturated, linear or branched hydrocarbon groups having a linear chain of 6 to 18 carbon atoms; provided that, when s is 2 and n, which are identical, are 2, at least one of the groups R represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and provided that, when s is 1 and n is 3, at least one of the groups R bonded to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

Description

EXAMPLES

[0185] In the following examples, lubricating compositions according to the invention, and comparative compositions, for example comprising monoesters or diesters other than those of the invention, in replacement of a diester in accordance with the invention, were formulated with the following components indicated in Table 1: [0186] The esters according to the invention and of the prior art were obtained by esterification reaction between a compound having at least two alcohol functions and at least two fatty acids, said acids being able to be identical or different. [0187] The esters of the prior art were also obtained by esterification reaction between a fatty acid having at least two carboxylic acid functions and at least two compounds having at least one alcohol function, said alcohols being able to be identical or different.

TABLE-US-00004 TABLE 1 KV 100° C. ASTM D445-97 (mm.sup.2/s) of the Ester Alcohol Acid 1 Acid 2 ester Diester 1 Neopentyl Octanoic Decanoic 2.51 (prior art) glycol acid acid Diester 2 2- Sebacic x 3.20 (prior art) Ethylhexanol acid Diester 3 Dipropylene Nonanoic x 2.66 (according to glycol acid the invention) Diester 4 Dipropylene Dodecanoic x 3.91 (according to glycol acid the invention) Diester 5 Mono- Dodecanoic x 3.36 (according to propylene acid the invention) glycol Diester 6 Neopentyl Nonanoic x 2.57 (prior art) glycol acid Diester 7 Neopentyl Dodecanoic x 4.33 (prior art) glycol acid

Example 1

[0188] Physicochemical Characterization of Lubricating Compositions According to the Invention and Comparative Compositions

[0189] Tables 2 and 3 below show details of the lubricating compositions according to the invention and comparative compositions as well as their physicochemical characteristics.

[0190] Lubricating compositions are obtained by simply mixing the following components at room temperature: [0191] Base oil 1 is a Group III base oil (kinematic viscosity at 100° C. measured according to ASTM D-556=4.11 mm.sup.2/s) commercially available for example from SK under the trade name “Yubase 4+”, [0192] Base oil 2 is a Group III base oil (kinematic viscosity at 100° C. measured according to ASTM D-556=6 mm.sup.2/s) commercially available for example from SK under the trade name “Yubase 6”, [0193] A conventional additive package 1 comprising a dispersant, detergents, an anti-wear additive, [0194] A conventional additive package 2, [0195] A conventional additive package 3, [0196] A conventional additive package 4, [0197] A viscosity index improver 1 which is a conventional hydrogenated polyisoprene styrene polymer commercially available from Infineum under the trade name “SV®”, [0198] A viscosity index improver 2 which is a conventional hydrogenated polyisoprene styrene polymer commercially available from Infineum under the trade name “SV®”, [0199] A viscosity index improver 3 which is a conventional polymethacrylate polymer commercially available from Evonik under the trade name “Viscoplex®”, [0200] A friction modifier which is a conventional organomolybdenum compound commercially available from Adeka under the trade name “Sakuralube®”, [0201] A pour point depressant additive which is a conventional polymethacrylate polymer commercially available from Evonik under the trade name “Viscoplex®”, [0202] An amino antioxidant additive commercially available from BASF under the trade name “Irganox®”

[0203] In Table 2, the component contents for each lubricating composition are given in percentages by weight based on the total weight of the lubricating composition.

[0204] The properties of the lubricating compositions thus prepared are listed in the following Table 3.

TABLE-US-00005 TABLE 2 CC1 CC2 CC3 C1 CC4 C2 C3 CC5 CC6 C4 CC7 CC8 C5 Base oil 1 82.6  66.9  66.9  66.9  80.9    64.4 64.9    66.4   66.4 56.7  57.1 64.0  48.8  Base oil 2 x x x x x x x x x x x 15.0  15   Additive package 1 9.4 9.4 9.4 9.4 x x x x x x x x x Additive package 2 x x x x 10   10 10   10 10 x x x x Additive package 3 x x x x x x x x x 21.8  21.8 x x Additive package 4 x x x x x x x x x x x 14.8  14.8  Viscosity index improver 1 6.8 7.5 7.5 7.5 x x x x x x x 2.0 2.2 Viscosity index improver 2 x x x x 8.5 10 9.5  8  8 x x x x Viscosity index improver 3 x x x x x x x x x 6.0  6.61 3.5 3.5 Friction modifier 0.5 0.5 0.5 0.5 0.6   0.6 0.6   0.6   0.6 x x 0.5 0.5 Pour point depressant additive 0.2 0.2 0.2 0.2 x x x x x 0.3  0.3 0.2 0.2 Antioxidant additive 0.5 0.5 0.5 0.5 x x x x x x x x x Diester 1(prior art) x 15   x x x x x x x x x x x Diester 2 x x x x x x x x 15 x 14.6 x x Diester 3 (invention) x x x 15   x 15 x x x 7.5 x x 15   Diester 4 (invention) x x x x x x x x x 7.5 x x x Diester 5 (invention) x x x x x x 15   x x x x x x Diester 6 (prior art) x x 15   x x x x x x x x x x Diester 7 (prior art) x x x x x x x 15 x x x x x

TABLE-US-00006 TABLE 3 Compo CC1 CC2 CC3 C1 CC4 C2 C3 CC5 CC6 C4 CC7 CC8 C5 KV 40° C. 44.46 41.13 41.49 41.22 31.20 28.6 29.4 30.0 30.0 29.7 29.9 43.03 39.43 ASTM D445- 97 (mm.sup.2/s) KV 100° C. 8.83 8.65 8.63 8.65 6.85 6.94 7.01 6.95 6.87 8.18 8.50 8.78 8.96 ASTM D445- 97 (mm.sup.2/s) Viscosity 182 196 193 195 187 218 214 205 200 271 284 189 218 index (VI) ASTM D2270- 93 HTHS at 2.60 2.64 2.60 2.57 2.29 2.30 2.31 2.31 2.30 2.62 2.65 2.90 2.92 150° C. ASTM D 4683 (cP) Volatility 13.0 15.7 15.0 13.5 12.3 14.0 11.9 11.1 ND ND ND 11.5 13.3 Noack ASTM D5800 (wt %) ND: NOT DETERMINED

Example 2

[0205] Characterization of Compositions According to the Invention and Comparative Compositions in Terms of Fuel Economy (“Fuel-Eco”)

[0206] The test is carried out using an EB 1.2 L Turbo engine with a power output of 81 kW at 5500 rpm, driven by an electric generator that can impose a rotation speed between 900 and 4500 rpm, while a torque sensor measures 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 temperature to the torque induced by the reference lubricating composition (SAE 0W30).

[0207] The conditions for this test are as follows.

[0208] The tests are carried out in the following sequence: [0209] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a reference lubricating composition; [0210] measurement of the friction torque at the four different temperatures indicated below on the engine using the reference lubricating composition; [0211] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a lubricating composition to be evaluated; [0212] measurement of the friction torque at four different temperatures on the engine using the lubricating composition to be evaluated; [0213] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with the reference lubricating composition; and [0214] measurement of the friction torque at the four different temperatures shown below on the engine using the reference lubricating composition.

[0215] The speed ranges, speed variation and temperature were chosen to cover, as representatively as possible, the points of the NEDC.

[0216] The instructions implemented are: [0217] Motor outlet water temperature: 35° C./50° C./80° C./100° C.±0.5° C., [0218] Oil temperature ramp: 35° C./50° C./80° C./110° C.±0.5° C.

[0219] The friction gain is evaluated for each lubricating composition (C1, CC1 to CC3) as a function of engine temperature and speed and in comparison with the friction of the reference lubricating composition.

[0220] The results of the “Fuel Eco” test are summarized in Table 4 below, and show the average percentage friction gains for each compound at a given temperature over a speed range from 900 rpm to 4500 rpm.

TABLE-US-00007 TABLE 4 Average percentage friction gains at a temperature t of the lubricating composition CC1 CC2 CC3 C1 t = 35° C. 2.2 2.9 3.9 5.0 t = 50° C. 1.9 2.1 2.8 3.7 t = 80° C. 0.8 0.2 1.4 1.6 t = 110° C. 0.9 0.3 0.5 1.0

[0221] These results show that the friction gains for the composition C1 comprising the ester according to the invention are much greater than the friction gains obtained with the comparative compositions CC1 comprising no ester, CC2 and CC3 comprising an ester different from those of the invention.

[0222] It is understood that the greater the friction gains, the greater the fuel economy or Fuel Eco. This therefore implies that the compositions according to the invention make it possible to increase the Fuel Eco as opposed to compositions comprising no ester or esters different from the esters of the invention.

Example 3

[0223] Characterization of Compositions According to the Invention and Comparative Compositions in Terms of Fuel Economy (“Fuel-Eco”)

The test is performed using a Nissan HR12DDR engine, with a power output of 180 kW at 6500 rpm, driven by an electric generator that can impose a rotation speed between 1000 and 4400 rpm, while a torque sensor measures the friction torque generated by the movement of the parts in the engine. The frictional torque induced by the test lubricant is compared for each speed and temperature to the average torque induced by the reference lubricating composition (SAE 0W16) which was evaluated before and after the test lubricant.

[0224] The conditions for this test are as follows.

[0225] The tests are carried out in the following sequence: [0226] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a reference lubricating composition; [0227] measurement of the friction torque at the four different temperatures indicated below on the engine using the reference lubricating composition; [0228] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a lubricating composition to be evaluated; [0229] measurement of the friction torque at four different temperatures on the engine using the lubricating composition to be evaluated; [0230] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with the reference lubricating composition; and [0231] measurement of the friction torque at the four different temperatures shown below on the engine using the reference lubricating composition.

[0232] The speed ranges, speed variation and temperature were chosen to cover, as representatively as possible, the points of the NEDC.

[0233] The instructions implemented are: [0234] Motor outlet water temperature: 30° C./50° C.±0.5° C., [0235] Oil temperature ramp: 30° C./50° C.±0.5° C.,

[0236] The friction gain is evaluated for each lubricating composition (C2, C3, CC4 to CC6) as a function of engine temperature and speed and in comparison with the friction of the reference lubricating composition.

[0237] The results of the “Fuel Eco” test are summarized in Table 5 below and show the average percentage friction gains for each compound at a given temperature over a speed range from 1000 rpm to 4400 rpm:

TABLE-US-00008 TABLE 5 Average percentage friction gains at a temperature t of the lubricating composition CC4 C2 C3 CC5 CC6 t = 30° C. −0.14 1.8 1.30 −0.75 −0.07 t = 50° C. 0.56 1.51 1.14 −0.77 0.39

[0238] These results show that the friction gains for compositions C2 and C3 comprising an ester according to the invention are much greater than the friction gains obtained with the comparative compositions CC4 comprising no ester and CC5 and CC6 comprising an ester different from those of the invention.

[0239] These results also show that the comparative compositions CC4 to CC6 do not show friction gains, but rather friction losses, which implies that the comparative compositions CC4 to CC6 do not allow for Fuel Eco but on the contrary lead to an overconsumption of fuel compared with the reference composition.

[0240] It is understood that the greater the friction gains, the greater the fuel economy or Fuel Eco. This therefore implies that the compositions according to the invention make it possible to increase the Fuel Eco as opposed to compositions comprising no ester or esters different from the esters of the invention, such as 2-ethylhexyl sebacate.

Example 4

[0241] Characterization of Compositions According to the Invention and Comparative Compositions in Terms of Fuel Economy (“Fuel-Eco”) The test is carried out using a Honda L13-B engine, with a power of 81 kW at 5500 rpm, driven by an electric generator that can impose a rotation speed between 650 and 5000 rpm, while a torque sensor measures the friction torque generated by the movement of the parts in the engine. The frictional torque induced by the test lubricant is compared for each speed and temperature to the torque induced by the reference lubricating composition (SAE 0W16).

[0242] The conditions for this test are as follows.

[0243] The tests are carried out in the following sequence: [0244] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a reference lubricating composition; [0245] measurement of the friction torque at the four different temperatures indicated below on the engine using the reference lubricating composition; [0246] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with a lubricating composition to be evaluated; [0247] measurement of the friction torque at four different temperatures on the engine using the lubricating composition to be evaluated; [0248] flushing the engine with a flushing oil comprising detergent additives, followed by flushing with the reference lubricating composition; and [0249] measurement of the friction torque at the four different temperatures shown below on the engine using the reference lubricating composition.

[0250] The speed ranges, speed variation and temperature were chosen to cover, as representatively as possible, the points of the NEDC.

[0251] The instructions implemented are: [0252] Motor outlet water temperature: 35° C./50° C.±0.5° C., [0253] Oil temperature ramp: 35° C./50° C.±0.5° C.

[0254] The friction gain is evaluated for each lubricating composition (C4 and CC7) as a function of engine temperature and speed and in comparison with the friction of the reference lubricating composition.

[0255] The results of the “Fuel Eco” test are summarized in Table 5 below, and show the average percentage friction gains for each compound at a given temperature over a speed range from 650 rpm to 5000 rpm:

TABLE-US-00009 TABLE 6 Average percentage friction gains at a temperature t of the lubricating composition C4 CC7 t = 35° C. 1.4 0.8 t = 50° C. 0.2 −0.2

[0256] These results show that the friction gains for composition C4 comprising a mixture of esters according to the invention are much greater than the friction gains obtained with the comparative composition CC7 comprising, as ester, 2-ethylhexyl sebacate, different from those of the invention.

[0257] It is understood that the greater the friction gains, the greater the fuel economy or Fuel Eco. This therefore implies that the compositions according to the invention make it possible to increase the Fuel Eco as opposed to compositions comprising no ester or esters different from the esters of the invention, such as 2-ethylhexyl sebacate.

Example 5

[0258] Evaluation of the Engine Cleanliness Improving Properties of a Lubricating Composition According to the Invention C5 and a Comparative Lubricating Composition CC8

[0259] Engine cleanliness performance on lubricating compositions C5 and CC8 is evaluated using the following method.

[0260] Each lubricating composition (10 kg) is evaluated during a cleanliness test of a common rail diesel engine for automobiles. The engine has a displacement of 1.4 L for 4 cylinders. Its power is 80 kW. The test cycle time is 96 hours with alternating idle and 4000 rpm. The temperature of the lubricating composition is 145° C. and the water temperature of the cooling system is 100° C. No draining or topping up of lubricating composition is carried out during the test. EN 590 fuel is used.

[0261] The test is carried out in two phases for a total duration of 106 hours and in a first stage of rinsing and running-in for 10 hours, then in a second stage with the evaluated composition (4 kg), and finally in an endurance stage lasting 96 hours with the evaluated composition (4 kg).

[0262] After this test, the engine parts were analyzed and the 4 pistons rated according to the European standard CEC M02A78. For each piston, its merit rating is made and then an average of the total piston merit rating of the 4 pistons is calculated.

[0263] The results obtained are grouped in Table 6.

[0264] The regular passage of a reference oil showed that a difference of 4 points between two candidates is significant.

[0265] The higher the value of the average merit rating, the better the cleanliness of the piston and therefore the better the performance of the lubricating composition to improve engine cleanliness.

TABLE-US-00010 TABLE 7 Evaluated Piston merit rating after composition test (%) C5 66.71 CC8 61.6

[0266] The results show that the use of an ester according to the invention in a lubricating composition improves the cleanliness of an engine (lubricating composition C5) compared with a comparative lubricating composition comprising no ester according to the invention (lubricating composition CC8).