Lubricating composition for a marine engine or a stationary engine

Abstract

Disclosed is a lubricant composition including: at least one base oil; at least one olefin copolymer; at least one detergent; and at least one hydrogenated and linear styrene/butadiene copolymer. Also disclosed is the use of this composition for reducing the fuel consumption of an engine and for improving the cleanliness of a 4-stroke or 2-stroke, preferably 4-stroke marine engine, or of a stationary engine.

Claims

1. A lubricant composition comprising: at least one base oil selected from the group consisting of oils of the group I, oils of the group II and mixtures thereof, according to the classes defined in the API classification; at least one detergent, in an amount being from 10% to 20% by mass based on the total mass of said lubricant composition; at least one olefin copolymer; and at least one hydrogenated and linear styrene/butadiene copolymer; wherein said at least one detergent is selected from the group consisting of alkaline or alkaline-earth of carboxylate and phenate detergents, wherein the amount of olefin copolymer is from 0.01 to 5% by mass and the amount of styrene/butadiene copolymer is from 2 to 8% by mass, wherein said at least one olefin copolymer is an ethylene-propylene copolymer and comprises a content of ethylene units ranging from 30% to 80% by mass based on the mass of copolymer olefin, and wherein in the hydrogenated and linear styrene/butadiene copolymer, the content of hydrogenated butadiene units ranges from 50% to 98% by moles, as compared with the number of moles of hydrogenated and linear styrene/butadiene copolymer.

2. A process for lubricating 4-stroke or 2-stroke marine engines, comprising the lubrication of the engine with a lubricant composition according to claim 1.

3. A process for reducing the fuel consumption while improving the cleanliness of 4-stroke or 2-stroke marine engines comprising contacting the lubricant composition according to claim 1 with the marine engine or the stationary engine.

4. The process according to claim 3, wherein the marine engine is a 4-stroke marine engine.

5. The lubricant composition according to claim 1, wherein in the hydrogenated and linear styrene/butadiene copolymer, the content of hydrogenated butadiene units ranges from 60% to 98% by moles, as compared with the number of moles of hydrogenated and linear styrene/butadiene copolymer.

6. The lubricant composition according to claim 1, wherein in the hydrogenated and linear styrene/butadiene copolymer, the content of hydrogenated butadiene units ranges from 70% to 97% by moles, as compared with the number of moles of hydrogenated and linear styrene/butadiene copolymer.

7. The lubricant composition according to claim 1, wherein the weight content of hydrogenated and linear styrene/butadiene copolymer is from 5% to 8% by mass, based on the total mass of the lubricant composition.

8. The lubricant composition according to claim 1, wherein the ethylene/propylene copolymer comprises a content of ethylene units ranging from 30% to 70% by mass based on the mass of copolymer olefin.

9. The lubricant composition according to claim 1, wherein the ethylene/propylene copolymer comprises a content of ethylene units ranging from 40% to 70% by mass based on the mass of copolymer olefin.

10. The lubricant composition according to claim 1, wherein the amount of olefin copolymer is from 0.01% to 2% by mass, based on the total mass of the lubricant composition.

11. The lubricant composition according to claim 1, wherein the amount of olefin copolymer is from 0.01% to 1% by mass, based on the total mass of the lubricant composition.

Description

EXAMPLES

(1) The compositions C.sub.1, O.sub.2, L.sub.1, L.sub.2 and L.sub.3 are obtained from the following components:

(2) The olefinic copolymer applied in the example comprises 67% by moles of ethylene units and 33% by moles of propylene units, 58% by mass of ethylene units and 42% by mass of propylene units, and has a mass average molecular mass comprised between 170,000 Da and 200,000 Da. They have a viscosity at 100° C. of 4,500 cSt when it is diluted to a content of 7% by mass in an oil of group 1.

(3) The commercial olefinic copolymer is diluted to 5% by mass in a base oil of group 1 for the compositions L.sub.1 and L.sub.3.

(4) The commercial olefinic copolymer is diluted to 2.3% by mass in a base oil of group 1 for the composition L.sub.2.

(5) The hydrogenated and linear styrene-butadiene copolymer applied in the examples comprises 82% by moles of hydrogenated butadiene units (including 32% by moles of addition 1-4 butadiene units and 50% by moles of 1-2 addition butadiene units) and 18% by moles of styrene units, 72% by mass of hydrogenated butadiene units (including 28% by mass of 1-4 addition butadiene units and 44% by mass of 1-2 addition butadiene units) and 29% by mass of styrene units.

(6) It has a mass average molecular mass comprised between 120,000 Da and 150,000 Da and has a polydispersity index comprised between 1 and 1.1.

(7) The commercial hydrogenated and linear styrene-butadiene copolymer is diluted to 8% by mass in a base oil of group 1 for the compositions L.sub.1, L.sub.2 and L.sub.3. a detergent packet 1 comprising detergents based on calcium carboxylates, calcium phenates, an anti-wear additive, zinc dithiophosphate (ZnDTP), an anti-foam agent and a friction modifier, the packet being diluted between 40 and 60% by mass in a base oil of group 1, a detergent packet 2 comprising detergents based on calcium carboxylates, calcium phenates, an anti-wear additive, zinc dithiophosphate (ZnDTP), an anti-foam agent, the packet being diluted between 40 and 60% by mass, in a base oil of group 1, base oils of group 2, in particular the bases known as 100R and 220R, respectively with a viscosity of 4.1 cSt and 6.4 cSt at 100° C., and 20.2 cSt and 41.5 cSt at 40° C. base oils of group 1, in particular bases known as Neutral Solvant 100NS and 150NS, having a respective viscosity of 4.1 cSt and 5.3 cSt at 100° C. and 20.2 cSt and 31.0 cSt at 40° C.

(8) The composition C.sub.3 is obtained from the following components: a hydrogenated styrene/isoprene (HIS) star copolymer comprising 90 mass % hydrogenated isoprene units and 10 mass % styrene units, having a mass Mw equal to 605,000, a mass Mn equal to 439,500, a polydispersity index of 1.4; the commercial copolymer is diluted to 10.7 Mass % in a base oil of group 1, a linear olefin copolymer (OCP) comprising 50 mass % ethylene units, with a mass Mw equal to 171,700, a mass Mn equal to 91,120, a polydispersity index of 1.9; the commercial copolymer is diluted to 12.5 mass % in a base oil of group 1, a package comprising calcium carboxylate-, calcium sulphonate-, and calcium phenate-based detergents with an anti-wear additive, ZnDTP, the package being diluted to 50 mass % in a group 1 base oil, base oils of group 1, in particular the bases known as Neutral Solvant 150NS and 33NS, respectively with a viscosity of 30 and 66 cSt at 40° C.

(9) The percent amounts of the various components are indicated in tables Ia and Ib below as mass % of the diluted products used, and not of the active material.

Example 1: Evaluation of the Temperature Resistance Properties of Lubricant Compositions of the Invention

(10) This is an evaluation of the temperature resistance of lubricant compositions according to the invention by means of the continuous ECBT test, thus simulating the cleanliness of the engine in the presence of such compositions.

(11) The following lubricant compositions were tested; the percentages given correspond to percent by mass.

(12) Tables Ia and Ib

(13) TABLE-US-00002 TABLE Ia Compositions C.sub.1 C.sub.2 L1 L.sub.2 L.sub.3 (compar- (compar- (inven- (inven- (inven- ative) ative) tion) tion) tion) Group 1 base oils 64.20 70.20 71.77 — 72.27 Group 2 base oils — — — 65.76 — Detergent package 1 — — 16.33 16.33 — Detergent package 2 15.80 15.80 — 15.83 Linear hydrogenated 20 6.9 6.9 6.9 styrene/butadiene copolymer (8 wt. % in base oil) Olefin copolymer — 14 5 — 5 (5 wt. % in base oil) Olefin copolymer — — — 11.01 — (2.3 wt. % in base oil)

(14) TABLE-US-00003 TABLE Ib Composition C3 (comparative) HIS 5 OCP 2.5 Detergent 12.7 ZnDTP 0.5 150NS 27.3 330NS 52.0

(15) The physical and chemical characteristics of the compositions of tables Ia and Ib are described in table II.

(16) TABLE-US-00004 TABLE II Compositions C1 C2 L1 L2 L3 C3 (comparative) (comparative) (invention) (invention) (invention) (comparative) Kinematic viscosity 13.95 13.77 11.06 10.8 10.93 14.30 in mm.sup.2/s (measured at 100° C. per ASTM D7279) Kinematic viscosity 87.28 92.24 72.34 66.8 69.69 109.3 in mm.sup.2/s (measured at 40° C. per ASTM D7279) Viscosity index (VI) 164.5 152 144 154 147 133 (calculated per ISO2908) HTHS viscosity (in 3.54 3.54 3.1 3.01 3.07 3.85 mPa.s per ASTM D4683) BN (per ASTM 30.1 30.2 29.7 30.5 29.8 29.8 D2896 in mgKOH/g)

(17) The temperature resistance of the compositions was thus evaluated using the continuous ECBT test, which measures the mass of deposits (in mg) generated in determined conditions. The lower this mass, the lower the temperature resistance, i.e., the better the cleanliness of the engine.

(18) This test simulates an engine piston that has been brought to a high temperature and on which the lubricant from the casing has been projected.

(19) The test uses aluminum beakers that simulate the shape of pistons. These beakers were placed in a glass container, kept at a controlled temperature by water circulation at 20° C.

(20) The lubricant was placed in these containers, which were equipped with a metal brush partially immersed in the lubricant. This brush was moved by rotation at a speed of 1000 rpm, creating a projection of lubricant on the lower surface of the beaker. The beaker was kept at a temperature of 310° C. by an electrical heating resistance regulated by a thermocouple.

(21) In the continuous ECBT test, the test has a duration of 12 h, and the projection of the lubricant was continuous. This procedure simulates the formation of deposits in the piston-ring assembly. The result is the weight of the deposits measured on the beaker.

(22) A detailed description of this test can be found in the publication “Research and Development of Marine Lubricants in ELF ANTAR France—The relevance of laboratory tests in simulatingfield performance”, by Jean-Philippe ROMAN, MARINE PROPULSION CONFERENCE 2000—AMSTERDAM—29-30 Mar. 2000.

(23) The results are grouped in table III below.

(24) TABLE-US-00005 TABLE III Compositions C.sub.1 C.sub.2 L.sub.1 L.sub.2 L.sub.3 C.sub.3 (comparative) (comparative) (invention) (invention) (invention) (comparative) Continuous 453 779 471 553 433 600 ECBT (mg) (beaker deposition mass)

(25) The results show that the compositions according to the invention have a good heat resistance and thereby give the possibility of improving the engine cleanliness.

(26) It should be noted that the lubricant compositions have improved heat resistance as compared with lubricant compositions comprising a single olefin copolymer and with lubricant compositions comprising an olefin copolymer in combination with a hydrogenated styrene-isoprene copolymer.

Example 2: Evaluation of the Fuel Consumption Saving Properties of Lubricant Compositions According to the Invention

(27) Here the problem is to determine, by simulation, the fuel consumption saving properties by the use of lubricant compositions according to the invention, by evaluating the traction coefficient on a MTM (Mini Traction Machine) machine according to the method described below. The tests were carried out on an MTM PCS machine in bead contact 10006 (standard steel AISI 52100) ultra polished with a diameter equal to 19.05 mm against a flat disc having the same material and surface condition characteristics as the beads.

(28) The following conditions were determined for their representativity of the engine operation in the SPC (Segment Piston Sleeve) area, the SPC area being the area of the engine in which the greater portion of friction takes place and therefore the area in which the fuel consumption gain may be maximized: load on the 25N bead, driving speed of 1 m/s, SRR (slipping/rolling ratio) of 100%, this ratio being equivalent to the slipping speed/rolling speed ratio, temperature of 90° C.

(29) Thus, under these conditions, the measured traction coefficient gives the possibility of efficiently predicting the fuel consumption gain of a lubricant composition; the lower the traction coefficient, better is the fuel consumption gain.

(30) The compositions were evaluated according to the method below; the results representing the traction coefficient of each composition are grouped in table IV.

(31) TABLE-US-00006 TABLE IV Compositions C.sub.1 C.sub.2 L.sub.1 L.sub.2 (compar- (compar- (inven- (inven- L.sub.3 ative) ative) tion) tion) (invention) Traction 0.036 0.036 0.032 0.031 0.032 coefficient

(32) The traction coefficient for the compositions according to the invention is reduced relatively to the comparative compositions C.sub.1 and C.sub.2.

(33) It is therefore observed that the association of an olefin copolymer and of a styrene-hydrogenated and linear butadiene copolymer gives the possibility of reducing the traction coefficient and thus gives the possibility of reducing friction.

Example 3: Evaluation of the Fuel Consumption Saving Properties of Lubricant Compositions According to the Invention

(34) The fuel saving properties of the lubricant compositions according to the invention were validated by a test conducted on a bench equipped with an engine MAN 5L16/24. The particular features of this engine were described in the publication entitled “INNOVATOR-4C, The cutting-edge MAN B&W 5L16/24 test engine”, by D. Lançon, V. Doyen and J. Christensen, CIMAC Congress 2004, KYOTO (Paper 124).

(35) A procedure dedicated to the stabilized conditions was developed by measuring the “fuel eco” properties of lubricant compositions according to the description hereafter. This procedure resorts to pieces of equipment which are usually found in test centers on an engine bench: Rinsing of the engine and of the lubrication circuits with the candidate lubricant, Running in of the engine with the candidate lubricant, Measurement of the fuel consumption of the distillate type (marine diesel oil—according to the specification ISO8217). The measurements are repeated so as to be sure of the accuracy, The fuel consumptions obtained with the candidate lubricant are compared with those obtained when a reference lubricant is tested under the same conditions, The operating conditions of the engine are: Speed: 1,000 rpm, Developed power: 100%, 75% and 25% of the maximum power, Temperature of the lubricant at the engine inlet: 68-70° C., Lubricant volume: 2×200 litres, The tests are organized according to a specific procedure which consists of regulating any test conducted with a candidate lubricant between two tests achieved with the reference lubricant. This gives the possibility of guaranteeing the operation stability of the engine as well as the statistically significant nature of the measured consumption differences between lubricants, In the present case, the reference lubricant is a commercial oil for semi-rapid 4 stroke engines of viscosity grades SAE40 and BN 30.

(36) The comparative composition C.sub.3 and the composition according to the invention L.sub.1 have been evaluated.

(37) The results, representing the fuel consumption gain for the different tested engine loads are grouped together in table V.

(38) TABLE-US-00007 TABLE V Fuel consumption gain (%) C.sub.3 L.sub.1 (compar- (inven- L.sub.2 L.sub.3 ative) tion) (invention) (invention) With an engine load of nd 1.09 1.07 1.29 100% With an engine load of 0.7 1.38 1.40 1.13 75% With an engine load of nd 2.70 nd 2.72 25% nd: not determined

(39) It is seen that the combination of a hydrogenated and linear styrene/butadiene copolymer and of a copolymer olefin allows, in the lubricant compositions L.sub.1, L.sub.2 and L.sub.3, a reduction of more than 1% of the fuel consumption with a load of 75% but also of more than 100% relatively to the reference oil unlike the composition C.sub.3 (comparative) comprising the combination of a hydrogenated styrene/isoprene copolymer and of a copolymer olefin which exclusively allows a reduction of 0.7% of the fuel consumption with a load of 75% relatively to the reference oil.

(40) Further, it was observed that the general aspect of the engine and of the cases after the test giving the possibility of demonstrating the fuel savings have low fouling, notably with visual scores of 7.5 over 10 for the case cleanliness and of 69.3 over 100 for the piston cleanliness, which is compliant with the reference oil, notably with 4-stroke marine engines, which also have low fouling, notably with visual scores of 7.5 over 10 for the case cleanliness and of 69.2 over 100 for the piston cleanliness.

(41) Thus, the examples above show that the lubricant compositions according to the invention have both a good heat resistance and therefore give the possibility of improving the engine cleanliness, while significantly reducing the fuel consumption, notably of fuel.