Long duration fuel economy lubricating composition

Abstract

In the field of lubricating compositions, in particular to the Fuel Economy (FE) properties of lubricating compositions, there is disclosed the combined use of at least one derivative of molybdenum and at least one derivative of boron to maintain the Fuel Economy (FE) properties of a lubricating composition also including at least one base oil. Also disclosed is a use, within a lubricating composition including at least one base oil, of a combination of at least one derivative of molybdenum and at least one derivative of boron, and at least 30 ppm and at most 600 ppm of born boron relative to the weight of the lubricating composition to preserve the Fuel Economy (FE) properties of this lubricating composition.

Claims

1. Method for preserving the Fuel Economy (FE) properties of a lubricating composition comprising at least one base oil, comprising the addition to the lubricating composition of at least one derivative of molybdenum and at least one derivative of boron, the final lubricating composition comprising at least 140 ppm and at most 600 ppm of boron relative to the weight of the lubricating composition, and at least 200 ppm and at most 600 ppm of molybdenum relative to the weight of the lubricating composition, and wherein the weight ratio of molybdenum to boron is from 2:1.4 to 5:2; wherein the derivative of molybdenum is an organo-molybdenum compound selected from the group consisting of a dithiocarbamate derivative of molybdenum (MoDTC), a dithiophosphate derivative of molybdenum (MoDTP) and a sulfur-free molybdenum complex; and wherein the boron derivative is selected from the group consisting of the derivatives of boric acid, the derivatives of boronic acid, boronates, borates, borated dispersants, borated detergents, simple orthoborates, borate epoxides and borate esters.

2. The method according to claim 1, wherein the Fuel Economy properties are measured: in accordance with Sequence VI-D conditions implemented as per standard ASTM D7589; or in accordance with the Plint SRV test; or in accordance with VI-D test conditions implemented as per standard ASTM D7589 and in accordance with the Plint SRV test.

3. The method according to claim 1, wherein the preserving of Fuel Economy properties is measured on the used lubricating composition in comparison with the fresh lubricating composition.

4. The method according to claim 1, wherein the preserving of Fuel Economy properties is measured on the used composition.

5. The method according to claim 1, wherein the preserving of Fuel Economy properties is higher than 25% as measured under VI-D test conditions implemented in accordance with standard ASTM D7589.

6. The method according to claim 1, wherein the lubricating composition also comprises at least one anti-wear additive.

7. The method according to claim 1, comprising the preserving of the Fuel Economy of a motor vehicle measured in accordance with VI-D test conditions implemented as per standard ASTM D7589.

8. The method according to claim 1, comprising the maintaining or reduced degradation of the coefficient of friction in a vehicle engine measured with the Plint SRV test.

9. The method according to claim 1, wherein the weight ratio of molybdenum to boron is from 2:1 to 5:2.

Description

EXAMPLE 1

Preparation and Evaluation of a Lubricating Composition Used in the Invention (1) and of Comparative Lubricating Compositions (1), (2) and (3)

(1) The lubricating compositions were prepared by mixing the compounds described in Table 1. The indicated percentages correspond to weight percentages relative to the total weight of the composition.

(2) TABLE-US-00002 TABLE 1 Composition of the invention comparative (1) (1) (2) (3) Group III base oils 80.25 81.45 80.75 80.25 Viscosity index improving polymers (PISH + 6.0 6.0 6.0 6.0 PMA) Mixture of additives (dispersant, detergents 10.25 10.25 10.25 10.25 of salicylate type, anti-wear of zinc dithiophosphate type) Pour point depressant (PPD) 0.3 0.3 0.3 0.3 Antioxidants (combination of phenolic 1.5 1.5 1.5 1.5 antioxidant + amino antioxidant) Borated ester 0.5 0.5 0   0   Non-borated ester 0   0 0   0.5 Friction modifiers: combination of MoDTP 1.2 0 1.2 1.2 (Sakuralube 300 ® by Adeka) + Mo-DTC (Sakuralube 525 ® by Adeka) Boron content (ppm) 133    133 0   0   Molybdenum content (ppm) 1 154     0 1 154     1 154    

(3) The lubricating compositions were subjected to a test of Plint SRV type such as described in the publication JSAE 9436260 (Frictional Characteristics of Organomolybdenum Compound with Addition of Sulfurized Additives Takashi Kikuchi, Yoko Yonekura, Kenyu Akiyama (Toyota Motor Corporation), pp. 105-108, 13) with: stroke: 2.2 mm, frequency: 30 Hz (0.13 m/s), load: 150 N, temperatures (° C.): 40, 50, 60, 70, 80, 90, 100, 110, 120, 140, 160, 180, 200, 240.

(4) The results are given in Table 2.

(5) TABLE-US-00003 TABLE 2 Composition Comparative Comparative Comparative (1) of the composition composition composition invention (1) (2) (3) Mean 0.044 0.125 0.049 0.047 coefficient of friction (μm)

(6) The same test was applied to the lubricating compositions after ageing i.e. subjected to oxidation under bubbling of air (10 L/h) for 96 h at a temperature of 150° C. The results are given in Table 3.

(7) TABLE-US-00004 TABLE 3 Comparative Composition of the composition after invention after ageing ageing (1) (1) (2) (3) Mean coefficient of 0.052 0.127 0.110 0.112 friction (μm)

(8) The lubricating compositions used in the invention have improved friction properties compared with lubricating compositions comprising either at least one derivative of molybdenum alone or a derivative of boron alone. These properties are sustained over time, even after ageing.

(9) Therefore, the lubricating compositions used in the invention afford improved performance to maintain a significant gain in fuel economy over time, even after ageing.

EXAMPLE 2

Evaluation of the Gain in Fuel Economy Performance of the Lubricating Composition (1) Used in the Invention

(10) The preserved Fuel Economy performance of the lubricating composition (1) used in the invention was evaluated with the Sequence VI-D test, in accordance with standard ASTM D7589.

(11) To meet this Sequence VI.D test: the value for the aged oil (FEI 2) must be at least 1.2%, the sum of the values for fresh oil (FEI 1) and aged oil (FEI 2) must be at least 2.6%.

(12) The results obtained are given in Table 4.

(13) TABLE-US-00005 TABLE 4 Composition (1) used in the invention FEI 2 (%) 2.32 FEI 1 + FEI 2 3.66 (%)

(14) The lubricating composition used in the invention successfully passed the Sequence VI-D test and therefore exhibits good Fuel Eco performance. This performance is sustained over time even after ageing.

EXAMPLE 3

Preparation and Evaluation of Lubricating Compositions (2), (3) and (4) Used in the Invention and of Comparative Lubricating Compositions (4), (5) and (6)

(15) The lubricating compositions were prepared by mixing the compounds described in Table 5. The indicated percentages correspond to weight percentages relative to the total weight of the composition.

(16) TABLE-US-00006 TABLE 5 Composition of the invention comparative (2) (3) (4) (4) (5) (6) Group III base oils 85.9 87.1 88.5 85.9 86.1 86.1 Viscosity Index improving 5.3 5.3 5.3 5.3 5.3 5.3 polymer (PISH) Pour point depressant (PPD) 0.3 0.3 0.3 0.3 0.3 0.3 Antioxidants (combination of 1.5 1.5 1.5 1.5 1.5 1.5 phenolic antioxidant + amino antioxydant) Mixture of additives (deter- 2.8 2.8 2.8 2.8 2.8 2.8 gents of sulfonate type, anti- wear of zinc dithiophosphate type) Friction modifiers (Mo-DTC 0.2 0.2 0.2 0.2 0 0 (Sakuralube 525 ® by Adeka)) Non-borated dispersant 0 0 0 4 0 4 (polyisobutylene succinimide) Borated dispersant (borated 4 2.8 1.4 0 4 0 polyisobutylene succinimide comprising 0.35 wt. % boron) Boron content (ppm) 140 100 50 0 140 0 Molybdenum content (ppm) 200 200 200 200 0 0

(17) The Plint SRV test of Example 1 was applied to fresh lubricating compositions and to lubricating compositions aged under the same conditions as described in Example 1. The results for fresh oils and aged oils are given in Tables 6 and 7 respectively.

(18) TABLE-US-00007 TABLE 6 Composition of the Comparative invention composition (2) (3) (4) (4) (5) (6) Mean coefficient of 0.056 0.056 0.056 0.056 0.147 0.145 friction (μm)

(19) TABLE-US-00008 TABLE 7 Composition of the Comparative invention composition (2) (3) (4) (4) (5) (6) Mean coefficient of 0.059 0.061 0.065 0.110 ≥0.147 ≥0.145 friction (μm)

(20) These results confirm those of Example 1. The lubricating compositions used in the invention exhibit improved friction properties compared with the lubricating compositions comprising at least one molybdenum derivative alone or a derivative of boron alone. These properties are sustained over time. As a result, the lubricating compositions used in the invention provide improved performance to maintain a significant gain in fuel savings over time.