Power transmitting fluids with improved materials compatibility
09732301 · 2017-08-15
Assignee
Inventors
Cpc classification
C10N2040/04
CHEMISTRY; METALLURGY
C10M2209/104
CHEMISTRY; METALLURGY
C10M2219/044
CHEMISTRY; METALLURGY
C10M161/00
CHEMISTRY; METALLURGY
C10M141/10
CHEMISTRY; METALLURGY
C10M2209/104
CHEMISTRY; METALLURGY
C10M2215/042
CHEMISTRY; METALLURGY
C10M2215/223
CHEMISTRY; METALLURGY
C10N2030/10
CHEMISTRY; METALLURGY
International classification
C10M139/00
CHEMISTRY; METALLURGY
C10M141/10
CHEMISTRY; METALLURGY
Abstract
A power transmitting fluid comprises a major amount of a lubricating oil and a minor amount of an additive composition. The additive composition comprises: (a) a friction modifier of the formula: ##STR00001## (b) an oil-soluble phosphorus compound; and, (c) an ashless dispersant;
wherein R.sup.1 and R.sup.2 may be the same or different and represent linear or branched, saturated or unsaturated hydrocarbyl groups having from 8 to 20 carbon atoms. Z represents a polyoxyalkylene segment or a polyalkoxylated alkyl amine segment. The friction modifiers provide the fluid with improved fluoroelastomer seal compatibility and enhanced copper corrosion compatibility.
Claims
1. A power transmitting fluid comprising a major amount of a natural lubricating oil and a minor amount of an additive composition, the additive composition comprising: (a) a friction modifier of the formula: ##STR00008## (b) an oil-soluble phosphorus compound: and (c) an ashless dispersant: where R.sup.1 and R.sup.2 may be the same or different and represent linear or branched, saturated or unsaturated hydrocarbyl groups having from 8 to 20 carbon atoms; wherein Q represents an alkylene group having 1 to 4 carbon atoms; and wherein a is an integer from 5 to 15.
2. A fluid according to claim 1 wherein Q or each Q is an ethylene group.
3. A fluid according to claim 2 wherein R.sup.9 is an alkyl group.
4. A fluid according to claim 1 wherein R.sup.1 and R.sup.2 are the same.
5. A fluid according to claim 1 wherein R.sup.1 and R.sup.2 are linear or branched, saturated or unsaturated alkyl groups having from 4 to 20 carbon atoms.
6. A fluid according to claim 1 wherein the fluid further comprises one or more corrosion inhibitors.
7. A fluid according to claim 1 wherein the fluid further comprises one or more metal-containing detergents.
8. A fluid according to claim 1, which is an automatic transmission fluid.
9. A method of formulating a power transmitting fluid with improved fluoroelastomer seal compatibility, the method comprising combining a major amount of a natural lubricating oil with a minor amount of an additive composition as defined in claim 1.
10. A method of formulating a power transmitting fluid with improved copper corrosion compatibility, the method comprising combining a major amount of a lubricating oil with a minor amount of an additive composition as defined in claim 1.
Description
EXAMPLE FM-1
Preparation of Friction Modifier
(1) A two liter flask fitted with an overhead stirrer and a Dean Stark trap with a condenser is charged with iso-stearic acid (2 moles, 568 g) and 400 molecular weight polyethylene glycol, ‘Dow Carbowax 400’ (1 mole, 400 g) and 0.2 g of an esterification catalyst (p-toluene sulfonic acid). The temperature of the mixture is then raised to 190-200° C. under a nitrogen sweep and maintained for around 10 hours during which time approximately 2 moles (˜35 g) of water was evolved. The mixture was then cooled to yield the product.
EXAMPLE FM-2
Preparation of Friction Modifier
(2) Example FM-1 was repeated replacing the iso-stearic acid with oleic acid (2 moles, 568 g).
EXAMPLE FM-3
Preparation of Friction Modifier
(3) Example FM-1 was repeated replacing the polyethylene glycol with ETHOMEEN® C-15 available from Akzo Nobel (˜1 mole, 425 g). The product obtained had a nitrogen content of 2.82 wt %.
EXAMPLE FM-4
Preparation of Friction Modifier
(4) Example FM-2 was repeated replacing the polyethylene glycol with ETHOMEEN® C-15 available from Akzo Nobel (˜1 mole, 425 g). The product obtained had a nitrogen content of 2.89 wt %.
COMPARATIVE EXAMPLE CFM-1
Preparation of Friction Modifier
(5) The procedure of Example FM-1 was repeated using tetraethylene pentamine (1 mole, 189 g) and iso-stearic acid (3.1 moles, 792 g). Approximately 3 moles of water was evolved during the course of the reaction and the final product had a nitrogen content of 6.4 wt %. CFM-1 is an example of a common type of commercial friction modifier used in automatic transmission fluids.
COMPARATIVE EXAMPLE CFM-2
Preparation of Friction Modifier
(6) Into a one liter round-bottomed flask fitted with a mechanical stirrer, nitrogen sweep, Dean Stark trap and condenser was placed iso-octadecenylsuccinic anhydride (1 mole, 352 g). Under a slow nitrogen sweep the material was stirred and heated to 130° C. Immediately, tetraethylene pentamine (0.46 moles, 87 g) was added slowly through a dip-tube. The temperature of the mixture increased to 150° C. where it was held for 2 hours. During this heating period, 8 ml of water (˜50% of theoretical yield) were collected in the trap. On completion, the flask was cooled and the product recovered. Yield: 427 g, nitrogen content: 7.2 wt %. CFM-2 is an example of a common type of commercial friction modifier used in automatic transmission fluids.
EXAMPLE D-1
Preparation of Borated PIBSA-PAM Dispersant
(7) A polyisobutenyl succinic anhydride (PIBSA) having a succinic anhydride (SA) to polyisobutylene (PIB) mole ratio (SA:PIB) of 1.04 was prepared by heating a mixture of 100 parts by weight of PIB (940 Mn; Mw/Mn=2.5) with 13 parts by weight of maleic anhydride. When the temperature reached 120° C. 10.5 parts by weight of chlorine were added at a constant rate over a period of 5.5 hours during which time the temperature was raised to 220° C. The reaction mixture was then held at 220° C. for 1.5 hours and then stripped with nitrogen for 1 hour. The resulting PIBSA had an ASTM saponification number of 112. The product was 90 wt % active ingredient, the remainder being primarily unreacted PIB.
(8) In a second stage, the PIBSA produced above (2180 g, ˜2.1 moles) was placed in a vessel equipped with a stirrer and a nitrogen sparger together with Exxon solvent 150 neutral oil (1925 g). The mixture was stirred and heated under nitrogen to 149° C. and Dow E-100 polyamine, a mixture of ethylene polyamines with an average of 5 to 7 nitrogen atom per molecule (PAM) (200 g, ˜1.0 mole) added over a period of approximately 30 minutes. After addition was complete, the mixture continued to be stirred under nitrogen for an additional 30 minutes (until no further water was evolved) before being cooled and filtered to recover the product. The product obtained had a nitrogen content of 1.56 wt %.
(9) In a final stage, the product of the second stage above (1000 g) was placed in a vessel equipped with a stirrer and a nitrogen sparger. The material was heated to 163° C. and boric acid (19.8 g) added over a period of one hour. After addition was complete, the mixture continued to be stirred under nitrogen for an additional 2 hours minutes before being cooled and filtered to recover the product. The product obtained had a nitrogen content of 1.56 wt % and a boron content of 0.35 wt %.
EXAMPLE 1
Friction Testing
(10) Fluids containing the friction modifiers of Examples FM-1, FM-2, FM-3 and FM-4 were tested together with similar fluids containing comparative example friction modifiers CFM-1 and CFM-2. For completeness, a fluid which did not contain a friction modifier was also tested. The compositions of the fluids tested are given in Table 1 below where “Test FM” refers to the friction modifier. Friction characteristics were evaluated using a low velocity friction apparatus. In this test, a small disc of friction material is run against a steel disc to simulate the environment in an automotive transmission clutch. The friction value determined is plotted against sliding velocity to give a friction versus velocity curve. The method can also be used to determine low speed or static friction. Further details of the test method can be found in “Prediction of Low Speed Clutch Shudder in Automatic Transmissions using the Low Velocity Friction Apparatus”, R. F. Watts & R. K. Nibert, 7.sup.th International Colloquium on Automotive Lubrication, Technishe Akademie Esslingen (1990).
(11) The role of the friction modifier in the fluid is to reduce the static friction, therefore examining the static friction of a fluid gives a good assessment of the friction reducing capability of the molecule under test.
(12) TABLE-US-00001 TABLE 1 Fluids for friction testing Component Function Mass percent product of Example D-1 dispersant 3.50 tri-lauryl tri-thio phosphite anti-wear agent 0.50 alkylated diphenyl amine anti-oxidant 0.50 hindered phenol anti-oxidant 0.30 tolyl triazole corrosion inhibitor 0.05 calcium sulphonate metal-containing detergent 0.10 polymethacrylate viscosity modifier 6.00 100 neutral mineral oil base fluid 86.05* Test FM friction modifier 3.00 Total 100.00 (*for the fluid which did not contain a friction modifier, an additional 3.00 wt % of the mineral oil was used)
(13) Values for static friction obtained from the Low Velocity Friction apparatus are given in Table 2 below. Each test was run at 4 different test fluid temperatures.
(14) TABLE-US-00002 TABLE 2 Static friction coefficient Friction modifier 40° C. 80° C. 120° C. 150° C. None 0.203 0.200 0.186 0.172 FM-1 0.100 0.089 0.085 0.084 FM-2 0.123 0.114 0.102 0.100 FM-3 0.103 0.097 0.095 0.093 FM-4 0.085 0.083 0.088 0.087 CFM-1 0.109 0.088 0.080 0.079 CFM-2 0.123 0.113 0.100 0.094
(15) From the result obtained, it can be seen that the fluid which did not contain any friction modifier gave rise to a very high static friction value. The friction modifiers which are included in the fluids of the present invention (FM-1, FM-2, FM-3 and FM-4) gave static friction values which are intermediate to the two known friction modifiers CFM-1 and CFM-2. This shows that the fluids of the invention display good friction characteristics.
EXAMPLE 2
Compatibility with Fluoroelastomers
(16) The friction modifiers tested in Example 1 were formulated into fluids with the compositions shown in Table 3 below. As before, a ‘blank’ sample fluid which did not contain any friction modifier was also tested. Dumb-bell shaped specimens of a fluoroelastomer material (an FKM materials designated V-51) commonly used to manufacture seals for use in vehicle transmissions were immersed in the test fluids and held there at 150° C. for 336 hours. After immersion, the specimens were removed from the fluid and stretched until they broke. Elongation at break and tensile strength were recorded. The volume swell of each specimen was also determined. Results are present in Table 4 below.
(17) TABLE-US-00003 TABLE 3 Fluids for fluoroelastomer compatibility testing Component Function Mass percent product of Example D-1 dispersant 3.50 tri-lauryl tri-thio phosphite anti-wear agent 0.10 alkylated diphenyl amine anti-oxidant 0.25 4 cSt Group III base stock base fluid 94.15* Test FM friction modifier 2.00 Total 100.00 (*for the fluid which did not contain a friction modifier, an additional 2.00 wt % of the base stock was used)
(18) TABLE-US-00004 TABLE 4 Fluoroelastomer compatibility testing Volume change Elongation at Tensile strength at Friction modifier (%) break (%) break (psi max) None 1.40 285 1274 FM-1 2.09 300 1476 FM-2 2.03 219 1090 FM-3 2.12 226 1049 FM-4 2.14 308 1491 CFM-1 3.26 163 754 CFM-2 2.98 152 719
(19) The data in Table 4 clearly show that the fluid which did not contain any friction modifier performed very well. The volume change was small and the elongation at break was high, as was the ultimate tensile strength. Contrastingly, the fluids which contained the known friction modifiers performed poorly. The fluids of the present invention containing (FM-1, FM-2, FM-3 or FM-4) were much closer in performance to the ‘blank’ sample and in the cases of FM-1 and FM-4, they outperformed the ‘blank’ sample both in terms of elongation at break and tensile strength.
(20) Overall, the testing performed confirms that fluids according to the present invention provide good friction characteristics and also show enhanced compatibility towards fluoroelastomer seals.
EXAMPLE 3
Compatibility with Copper
(21) Two mass percent of each of FM-1, FM-2, FM-3 and FM-4 as well as the same amount of CFM-1 and CFM-2 were individually dissolved in a commercial API Group III base stock. The solutions so prepared were used in a copper dissolution test which was run according to the ASTM D-130 procedure except that the test lubricant was maintained in contact with the copper test strip at 150° C. for 24 hours. At the end of the 24 hour test a sample of each lubricant was tested using ICP spectroscopy to determine the copper content. Results are shown in Table 5 below where the amount of copper in each sample is expressed as parts per million of copper in the oil by weight.
(22) TABLE-US-00005 TABLE 5 Copper dissolution - 24 hours at 150° C. Friction modifier CFM-1 CFM-2 FM-1 FM-2 FM-3 FM-4 ppm, Cu 84 35 3 3 6 4
(23) The results show that the fluids containing FM-1, FM-2, FM-3 and FM-4 are much more compatible with copper than either fluid containing CFM-1 or CFM-2 (as evidenced by the clear reduction in copper dissolution into the fluid).