MXPA03001736A - Low phosphorus lubricating oil composition. - Google Patents

Abstract

This invention relates to a lubricating oil composition used in conjunction with a gasoline fuel having a sulphur content of less than 10 ppm by weight, characterised in that said oil composition has a phosphorus content of no more than 0.05 % by weight. The feature of the invention is that the use of a low sulphur fuel enables the amount of anti-wear agents containing phosphorus such as eg ZDDP to be halved without any adverse effect on the antiwear performance of the lubricating oil.

Description

COMPOSITION OF LOW LUBRICANT OIL IN PHOSPHORUS DESCRIPTION OF THE INVENTION The invention relates to low-phosphorus lubricating oil compositions for use in conjunction with ultra-low sulfur gasoline compositions in order to reduce exhaust emissions without adversely affecting fuel economy. Fuels such as gasoline for engines are widely used in automotive transport. However, in line with the general commitment to reduce air pollution, oil companies and vehicle manufacturers are looking to develop systems that have reduced exhaust emissions and improved fuel economy. The oil companies, in turn, are introducing fuels with a low sulfur content that they consider to be more compatible with the exhaust pipe catalytic systems. Such fuels are generally used in conjunction with lubricating oils which inevitably contain phosphorus in the form, for example, of zinc dialkyl dithiophosphate (ZDDP). It has been thought that gasoline for low sulfur motor can transfer acid species in the fuel-air mixture that is lost when passing through the rings of the EF: 145329 pistons (said mixture called hereinafter "blow-by") and therefore impart less effort in the detergency properties on which the lubricating oil is based as would a relatively high sulfur motor gasoline. It would also be expected that there would be a corresponding reduction in any contrary impact on the performance of the antioxidant and anti-wear components of such oils. It has also been recognized now that phosphorus also has a detrimental effect on exhaust pipe catalytic systems. Consequently, the development of lubricating oil formulations with reduced phosphorus content has been an objective. However, while ZDDP is the key anti-wear agent in lubricating oil formulations, excessive engine wear can also be reduced to some degree by supplementing the ZDDP with other phosphorus-free anti-wear agents such as, for example, oligomeric esters . This issue of wear is worrisome, especially with fuels with ultra low sulfur content, since reducing the sulfur content can adversely affect the lubricity of the resulting fuel and can lead to premature wear in some submerged electric gasoline pumps. In addition, the loss of lubricity can also result in the loss of fuel economy.

Experiments carried out in the context of the present invention have shown that the greatest effect of the use of fuels with ultra-low sulfur content in conjunction with conventional lubricating oils in anti-wear performance of the lubricating oil formulations reflected by the iron content in the oil used. Surprisingly it was found that low sulfur motor gasoline caused less wear than high sulfur motor gasoline despite the reduced sulfur content which until now was known to adversely affect lubricity. More importantly, this led to the observation that the phosphorus content of the lubricating oil composition could be reduced by half without adversely affecting the wear protection achieved by such oils. More surprising is that, by decreasing the phosphorus content of the lubricating oils and the sulfur content of the fuel, a synergistic benefit was obtained, providing the lowest iron content of all even when the decrease in sulfur content and phosphorus will increase the wear indicated by the iron content. This suggests that lubricating oils for use in conjunction with low sulfur fuel can therefore be formulated with reduced levels of phosphorus without adversely affecting wear performance.

Therefore, it has now been found that low-phosphorus lubricating oils can be used in conjunction with ultra-low sulfur fuels without adversely affecting the performance of fuel economy or the efficiency of a vehicle's exhaust catalyst system. . Accordingly, the present invention is a lubricating oil composition used in conjunction with a gasoline fuel having a sulfur content of less than 10 ppm by weight, characterized in that said oil composition has a phosphorus content not greater than 0.05% by weight. . Therefore in one aspect, the invention is the use in an internal combustion engine that operates with a gasoline fuel having a low sulfur content of less than 10 ppm by weight, of a lubricating oil composition having a phosphorus content. not greater than 0.05% by weight, for the purpose of reducing environmental pollution. As described above, the sulfur content of the fuel composition is less than 10 ppm by weight, preferably less than 5 ppm by weight. The sulfur measurement methods used were by X-ray (ASTM D2622-1) or by UV (ASTM D5453-93). Such low levels of sulfur can be obtained in various ways. The base fuels may comprise mixtures of saturated, olefinic and aromatic hydrocarbons and these may be derived from primary distillation streams, charges from thermally or catalytically disintegrated hydrocarbons, hydrodisintegrated petroleum fractions, catalytic reforming hydrocarbons, or mixtures of synthetically produced hydrocarbons such as those methane derivatives. Typically, the present invention is applicable to fuels such as light boiling gasoline (which typically boils between 50 and 200 ° C), especially motor gasoline. The sulfur content of such fuels can be reduced below the level of 10 ppm by well-known methods such as, for example, catalytic hydrodesulphurisation. The lubricating oil compositions used in conjunction with ultralow sulfur content fuels in the present invention are suitably the base materials of Group II, Group III, or Group IV as defined by the API and preferably are the base materials of the Group. II. These compositions suitably contain conventional additives selected from the group consisting of: phenolic and / or arninic antioxidants, demulsifiers, viscosity index improvers, antiwear agents, alkaline earth metal sulfonates, and polyisobutenyl succinimides which optionally may be borated. These oil compositions conveniently have: a kinematic viscosity at 40 ° C (KV40) of about 75 cSt or less, preferably 50 to 75 cSt, more preferably 60 to 70 cSt (for examples of about 66 to 67 cSt); a KV40 less than 20 cSt, preferably from 10 to 15 cSt (for example about 11 cSt); a pour point of less than -20 ° C, preferably less than -30 ° C (for example, of about -33 ° C) a flash point greater than 200 ° C, preferably greater than 215 ° C (for example 220 ° C) C); NOACK volatility of up to 15% (for example 14.3%); a TBN value of about 7, for example from about 7.15 to 7.25, for example from 7.19 to 7.22 based on milligrams of KOH per gram (in accordance with ASTM method 2896-98); and a nitrogen content measured by the Kjeldahl method of less than 0.1% by mass, for example 0.08. A typical example of such an oil composition is a grade 5W40 oil. A feature of the oil compositions of the present invention is that they have a considerably reduced amount of anti-wear agent, ZDDP, and consequently of phosphorus therein. For example, conventional oil compositions have a phosphorus content of about 0.09 to 1.0% by weight while the lubricating oil composition used in conjunction with the ultra-low sulfur fuels of the present invention only needs a phosphorus content. less than 0.05% by weight, for example of approximately 0.046, which is approximately half of that used so far with low sulfur fuels. The ZDDP contributing to the phosphorus content of the lubricating oils used in the present invention conveniently has primary alkyl groups with 1 to 18 carbon atoms, secondary alkyl groups with 3 to 18 carbon atoms or a mixture of such primary and secondary alkyl groups . The present invention is further illustrated with reference to the following examples. EXAMPLES The test program tabulated below shows that the tests were conducted using low and high sulfur (S) motor oil ("mogas") and lubricating oils with low and high phosphorus (P) levels.

The tests were carried out in the order presented in the table. Tests 1 and 2 were carried out first and after the initial data were analyzed the fuel was tested with low S in combination with an oil with low P. The compositions of the fuels and lubricating oils are shown in the following table 1 : Fuels - mogas with high 3 A 700 ppm of S - mogas with low SB 9 ppm of S TABLE 1 Composition analysis of the fuels tested »DESCRIPTION OF THE TEST AB UNITS RON 97.6 91.1 MON 85.0 89.9 DENSITY 0.766 0.733 g / ml @ 15 ° C APPEARANCE Fault C and B (particles) EXISTING GUM 2.2 2 mg / 100 ml WASHED GUM 0.8 0 mg / 100 ml DISTILLATION Initial Boiling Point 25.5 32.2 ° C Final boiling point 199.5 200.7 ° C E70 ° C 23.4 36.1 mi E100 ° C 41.8 56.5 mi E150 ° C 87.1 84.8 mi FIA Aromatics 43.8 22% v / v Olefins 23.2 0.5% v / v Saturated 33 77.5% v / v SETAVAP 654 50.9 mbar / kPa STRAW BY RATS X 0.07% by weight SULFUR FOR UV 9 mg / kg DO NOT. DE BROMO 33.87 0.95 UVA 319 0.43 0.43 A / Uts LEAD CONTENT 3.4 < 1 mg / 1 NITROGEN 0.3 ppm w / w Nitrogen in H / Carbonos 20.7 ppm weight / weight MTBE BY GO 0 0% in vol.

CHROMATOGRAPHY ANALYSIS OF GAS Benzene Not analyzed 2.23% vol.

Toluene Not analyzed 12.56% vol.

Xylene Not analyzed 7.21% vol.

CHN BY COMBUSTION Carbon Not analyzed 87.6% Hydrogen Not analyzed 12.4% Nitrogen Not analyzed < 0.1% * Lubricating oils-Oil with high P C was not measured) Both oils Oil with low P D) approx. to grade 5W40 The following tables 2-4 show the details of formulation and compositional analysis of these lubricating oils. Table 2 Formulation of lubricating oil with high phosphorus C) Table 3 Formulation of lubricating oil with low phosphorus D) Component Component Chemical Combinations Ratio PBR 9330 Calcium Sulphonate 300 TBN 1.55 PBR 9260 ????? PAM borada PM of 2225 6 PX 14 ZDDP with sec-alkyl groups 0.6 IRG L150 Phenolic antioxidants / 1 mixed amines PBR 9499 Desemulsifier 0.01 PTN 8464 Viscosity Meter 8.8 Base material Base material of Group II 82.04 IOL 120X Table 4 Fresh Oil Analysis i Additive Elements Boron% by weight 0. 015 0. 014 Barium% by weight < 0,001 < 0,001 Calcium% by weight 0. 179 0. 179 Copper% by weight < 0,001 < 0,001 Magnesium% by weight < 0,001 < 0,001 Molybdenum% by weight < 0,001 < 0,001 Phosphorus% by weight 0. 093 0. 046 Sulfur% by weight 0. 226 0 .13 Silicon mg / kg 4 5 Zinc% by weight 0. 105 0. 052 Cont. Of N (Kjeldhal)% mass / mass 0. 082 Foam Stage 2 Foam after 5 ml 0 min of blowing Foam after 10 ml 0 min of sedimentation Motor Testing All engine tests were performed on a 3.8 L GM Buick engine. The standard cycle for this engine is of average severity and lasts for 109 hours and the protocol used is summarized in the following table 5 using a procedure Internal Exxon: Table 5 Engine speed cycle Motor 3.8 kW GM Buick Stage Duration Motor Speed Torque minutes: seconds revolutions / min Nm 1 10:50 1700 48.8 2 15:57 1465 76.2 3 10: 50 1700 48.8 4 24: 08 1465 76.2 5 17:35 1265 36.6 6 15:57 1465 76.2 Under the standard test conditions used, the lubricant collector is discharged and filled with oil under test ("test oil") before the test begins. At the end of the test the head of the cylinder is removed and the level of deposits of the intake valve and the combustion chamber (visual qualification and / or weights) is measured. To test the compositions of the present invention, the engine was flushed with low P oil discharge before filling and then the test was carried out under the standard cycle. At the end of the test the engine was dismantled and evaluated in the normal way and the used oil was recovered for analysis. Small oil samples (approximately 50 ml) were collected during the test, after 24, 48 and 72 hours, in such a way that the effects could be monitored throughout the test. Analysis of used oil - Bank test strategy Samples of fresh oils and used end-of-test oils (EOT) were analyzed for all tests and these are listed below (tables 6 and 7). In addition, the intermediate samples, which were only available in limited quantities (50 ml), were analyzed by means of a limited set of tests (Table 6). Table 6 Tests for all oil samples Additional tests for fresh oils and EOT Purpose Test Volume 6 Viscometric change KV40 50 7 Viscometric shift K 100 50 8 Oil dilution Fuel dilution 30 9 Wear Metals additives 5 The results obtained are summarized in tables 8 to 11 below. These tables do not report the concentration of metals that did not undergo any significant change as a result of the test. In the tables, the metals worn by the ICP tests were performed as described in the ASTM D5185 method and the KV values were determined in accordance with the method ???? D445 Table 8? Reaultadoa IVD gives motor test Table 8B Results Motor test CCD Fuel Measurement with Fuel with high S (A) under sulfur (B) CCD mg / cylinder (average) 1256 551 PTD mg / cylinder (average) 1505 698 Total 2761 1249 Table 9 Results at bench scale for virgin oil and uaadoa at the end of the test (Engine tests 1 and 2) DescripAceite CombustiCombustición de virgen ble con ble with sample of C low S of high S of final oil of end of lubricant test test Probe Units Kinematic viscosity at 40 ° C (ASTM D445) cSt 68.1 64.8 65.8 Kinematic viscosity at 100 ° C (ASTM D445) CSt 11.3 11.0 11.0 TAN (ASTM D664) mg KOH / g 1.95 1.78 2.05 SAN (IP 182/82) mg KOH / g 0 0 0 pH 7.86 5.64 5.62 TBN (ASTM D2896) mg KOH / g 7.17 6.63 6.24 Loss% 0 8 13 Dilution of Combustivol / vol% without sin 0.2 (IP 23/83) dilution dilution DSC Oxidation Stability 5 ° C / min Temp. of degradation * C 247.8 227.0 225.8 Temp. Initial Extrapolated ° c 250.2 233.6 230.3 Reduction in Temp. of degradation ° C 0 16.6 19.9 Oxidation stability DSC 210"C / 200 mi Induction time min 53.3 19.3 12.6 Initial time extrapolated min. 55.2 20.5 13.8 Reduction in induction time min. 0 34 40.7 Metals chipped by ICP (ASTM D5185) Bar or mg / kg < 1 2 2 Chromium mg / kg < 1 < 1 2 Copper mg / kg < 1 4 14 Iron mg / kg < 1 17 40 Molybdenum mg / kg 2 3 3 Phosphorus mg / kg > 180 > 180 > 180 Lead mg / kg < 1 < 1 3 Silicon mg / kg 2 66 63 Determination of elements in Used oil (ASTM D51I B5) Boron% by weight 0.014 0.008 0.008 Magnesium% by weight < 0.001 < 0.001 0.005 Phosphorus% by weight 0.093 0.087 0.082 Sulfur% by weight 0.224 0.204 0.253 Silicon% by weight 3 > 50 > 50 TABIA 10 Results for fresh oil, EO oils and intemediate samples (Motor tests 1 and 2) Fuel with baio S B Fuel with high S A Test Time 0 24 48 72 EOT 0 24 48 72 EOT 5 TAN mgKOH / g 1.51 1.69 1.75 1.79 2.1 1.51 1.73 1.76 1.97 2.2 SAN mgKOH / g 0 0 0 0 0 0 0 0 0 0 pH 8.47 7.32 6.55 6.28 5.95 8.47 7.46 6.65 5.96 6.11 TBN mgKOH / g 7.16 6.92 6.86 6.87 6.62 7.16 7.06 7.01 6.89 6.24 % of losses 0 3 4 4 8 0 1 2 4 13 Oxidation stability DSC 5eC / min Temp. of degradation ° C 251.2 243.0 239.6 234.1 231.9 251.2 238.1 234.9 230.1 226.4 Temp. Initial 15 extrapolated ° C 252.6 244.7 242.3 237.7 234.6 252.6 241.1 237.8 235.4 231.6 Reduction in Temp. of degradation ° C 0.0 7.9 10.3 14.9 18.0 0.0 11.5 14.8 17.2 21.0 Reduction in Temp. deqradation% 0.0 3.1 4.1 5.9 7.2 0.0 4.6 5.9 6.8 8.4 Oxid stability. DSC 210 ° C / 200mil Induction time Min. 57.4 43.6 36.7 30.3 23.5 57.4 23.6 21.1 20 15.2 Initial time extrapolated (EOT) Min. 60 44.8 37.8 31.5 24.5 60 24.6 22.6 21.3 16.4 Reduction in induction time Min. 0 13.8 20.7 27.1 33.9 0 33.8 36.3 37.4 42.2 Reduction in induction time% 0 23 35 45 57 0 56 61 62 70 Metals worn by ICP Copper mg / kg < 1 3 2 3 4 < 1 11 11 12 14 Iron mg / kg < 1 8 10 14 17 < 1 11 19 25 40 Sodium mg / kg < 1 5 5 5 5 < 1 7 7 7 6 Fós forum mg / kg > 180 > 180 > 180 > 180 > 180 > 180 > 180 > 180 > 180 > 180 35 Lead mg / kg < 1 < 1 < 1 < 1 < 1 < 1 4 2 2 2 Silicon mg / kg 2 38 50 59 69 2 36 50 57 67 TABLE 11 Result »of fresh oil, EOT oils and sample» intermediate (Engine test 3) Fuel with low S B Oil 24 48 72 Fresh EOT hrs hrs hrs Test Units TAN mg KOH / g 1.32 1.12 1.15 1.27 1.6 SAN mg KOH / g 0 0 0 0 0 PH 9.29 7.09 6.59 6.18 6.99 TBN mgKOH / g 7.22 6.84 6.71 6.44 5.76 % of losses 0 6 7 11 22 Oxidation stability DSC 5oC / min Degradation temperature ° C 244.8 235.6 230.1 224.4 217.6 Initial temperature extrapolated ° C 246.8 237.3 232.1 226.9 220.2 Reduction in temp of degradation ° c 0 9.2 9.2 20.4 27.2 Reduction in temp of degradation% 0 4 6 8 11 Oxidation stability DSC 210 ° C / 200 mi Induction time Min 33.7 18.6 13.3 5.8 1.2 Initial time extrapolated (EOT) Min 35.1 19.7 14.3 6.6 1.9 Reduction in induction time Min 0 15.1 20.4 27.9 32.5 Reduction in induction time% 0 45 61 83 96 Kill them dasgaatados by ICP Copper mg / kg < 1 7 7 8 9 Iron mg / kg < 1 5 6 6 6 Sodium mg / kg < 1 5 5 5 6 Phosphorus mg / kg > 180 > 180 > 180 > 180 > 180 Silicon mg / kg 3 36 45 53 63 Determination of used oil elements Copper% by weight < 0.001 < 0.001 Phosphorus% by weight 0.046 0.044 Sulfur% by weight 0.13 0.126 mg / kg Silicon 5 52 KV40 cSt 66.32 65.62 KVioo cSt 11.08 10.95 Dilution of No fuel Due to a complex interaction between the different properties of the fuel, the interpretation of this data is not direct. For example, the viscosity of the oil can impact in several ways, for example, the dilution of the fuel can reduce the viscosity while the oxidation and the suspension of particles can increase it. Similarly, the content of? of the oil can be increased by the transfer of products of combustion via "blow-by" but could be reduced by the reaction of ZDDP or through the dilution of fuel. However, there are some interesting effects observed from these data. The main observations made are summarized below. Effects of wear | When the oil with high P was used the Fe content was higher in the oil test used in high sulfur motor gasoline. - The results for the intermediate samples were consistent with this (see Figure 1). - Low levels of P and Zn were measured in the same oil samples. The differences are small but they are consistent and are reproducible based on the original oil analyzes. When the oil was tested with low P in combination with low sulfur motor gasoline the level of Fe was even lower than in tests 1 and 2. - This was somewhat surprising because it would have been expected that the lower concentration of ZDDP gave higher levels of Fe (compared to test 2).

- Other results (for example DSC) are consistent with lower levels of ZDDP in the oil. The staggered reduction in Fe levels from test 1 to test 2 to test 3 may give the impression of a gradual decrease in severity over time. However, current knowledge of motor tests would not support this. In addition, the engine test was not new at the beginning of the present study and therefore has been completely operated on previous test work. Antioxidation | Fuel oils tested in low sulfur motor gasoline retain higher antioxidant performance at the end of the test. - The oils used for test 1 (high S engine petrol) had a slightly lower DSC degradation temperature and a slightly shorter induction time than the corresponding oils of test 2. | The anti-oxidation performance of the oil deteriorated when the concentration of ZDDP was reduced by half. This was expected because it is also known that the ZDDP possesses antioxidant properties as well as being an anti-wear agent. Therefore, it may be necessary to supplement the amount of antioxidants used in the formulations for optimal performance.

Acid Neutralization The fuel composition can also impact the TBN loss rating and increase in TAN but only in a small amount. -The oil test in motor gasoline with low S (test 2) lost less TBN than that of test 2. -The oil test in motor gasoline with high S (test 1) had higher TAN than that of test 2. - The oil in test 3 (oil with low P / gasoline engine with low?) showed the largest reduction in TBN. S content The sulfur content of the used oil also seems to be influenced by the fuel composition. -The oil test in high-S engine gasoline (test 1) showed a greater increase in S than the fresh oil while the oil test in low-S engine gasoline (test 2) had a slightly lower S increase . - When low-sulfur motor gasoline was tested with the oil with low P the end-of-test oil had approximately the same S content as the fresh oil. Viscosity | All end-of-test oils had slightly lower viscosity than virgin oil.

Dilution d * Fuel | In the tests, little or no fuel dilution was observed. CCD / IVD | Fuel based on high S content created a significantly higher level of deposits (CCD and IVD) than low gasoline? The tests carried out now showed that: The fuel composition seems to impact the performance of the lubricating oil in key areas. The greatest effect observed was in the anti-wear performance reflected in the Fe content of the oil used. Engine gas with low S caused less wear than high engine gasoline? By using motor gasoline with low?, It was possible to halve the P content of the oil without damaging effect on the wear protection. Low-S motor gasoline also appears to have less detrimental effect on antioxidation and the performance of acid neutralization (TBN) of the oil. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property.

1. The use of a lubricating oil composition in an internal combustion engine that operates on gasoline fuel with a sulfur content of less than 10 ppm by weight, characterized in that the lubricating oil composition has a phosphorus content of not more than 0.05% by weight. weight.

2. The use according to claim 1, characterized in that the gasoline fuel has less than 5 ppm by weight of sulfur.

3. The use according to claim 1 or 2, characterized in that the lubricating oil composition comprises Group II, Group III or Group IV base materials as defined by the API.

4. The use according to any of the preceding claims characterized in that the lubricating oil composition has a kinematic viscosity at 40 ° C of about 75 centistokes or less and at 100 ° C of less than 20 centistokes; a pour point less than -20 ° C; a flash point greater than 200 ° C; NOACK volatility of up to 15%; a TBN value of about 7 based on milligrams of potassium hydroxide per gram (in accordance with ASTM Method 2896-98); and a nitrogen content measured by the Kjeldahl method of less than 0.1% by mass.

5. The use according to any of the preceding claims, characterized in that the lubricating oil composition is a grade 5 oil.

6. The use according to any of the preceding claims characterized in that the lubricating oil composition further comprises one or more additives selected from the group consisting of antioxidants, viscosity index improvers, antiwear agents, demulsifiers, alkaline earth metal sulfonates and polyisobutenyl succinimides. which are optionally boradas. The use according to any of the preceding claims characterized in that the lubricating oil composition comprises zinc dialkyldithiophosphate (ZDDP) as an antiwear agent in an amount such that the phosphorus content of the composition is less than 0.05% by weight . 8. The use according to claim 7 characterized in that the zinc dialkyldithiophosphate has primary alkyl groups having from 1 to 18 carbon atoms, secondary alkyl groups having from 3 to 18 carbon atoms or a mixture of such primary alkyl groups and secondary. 9. The use according to any of the preceding claims 6 to 8 characterized in that the antioxidant is phenolic, aminic or mixtures thereof. 10. A method of operation of internal combustion engines, characterized in that the method comprises the use of a lubricating oil composition, which has a phosphorus content not greater than 0.05% by weight, in conjunction with a gasoline fuel having a sulfur content of less than 10 ppm by weight. 11. A method for reducing wear in an internal combustion engine, characterized in that the method comprises the use of a lubricating oil composition, which has a phosphorus content not greater than 0.05% by weight, in conjunction with a fuel of gasoline having a sulfur content of less than 10 ppm by weight. 12. A method of reducing environmental pollution caused by the operation of an internal combustion engine and at the same time reducing the deposit in said engine, characterized in that the method comprises the use of a lubricating oil composition, which has a phosphorus content not greater than 0.05% by weight, in conjunction with a gasoline fuel having a sulfur content of less than 10 ppm by weight.