Antiwear automotive formulations
An automotive engine oil comprising a base oil and an antiwear additive system comprising an ester. The antiwear additive system preferably further comprises a phosphorus-containing and/or sulphur-containing antiwear additive. The antiwear additive system of the invention has superior antiwear properties and also reduced metal, phosphorus and sulphur levels compared to current commercial antiwear agents such as ZDDP.
1. A method of reducing wear in an automotive engine by the addition to the engine an automotive engine oil comprising a base oil and an ester which is the reaction product of
(a) at least one polyfunctional alcohol;
(b) a dimer fatty acid having a dimer content of greater than 94% by weight; and
(c) at least one of an aliphatic dicarboxylic acid having 5 to 18 carbon atoms and an aliphatic monocarboxylic acid having 5 to 24 carbon atoms;
wherein the resultant ester has a kinematic viscosity at 100° C. ranging from 1500 to 5000 mm 2 /s and a non-polarity index (NPI)
NPI
=
total
number
of
carbon
atoms
×
molecular
weight
number
of
carboxylate
groups
×
100
of at least 500; and
wherein the automotive engine oil has a phosphorus level of no more than 0.08%.
2. The method of claim 1 , wherein (c) is an aliphatic dicarboxylic acid having 5 to 18 carbon atoms.
3. The method of claim 1 , wherein the polyfunctional alcohol is a polyol of formula R(OH)n where n is an integer which ranges from 1 to 10 and R is a hydrocarbon chain of 2 to 15 carbon atoms where the polyol is of molecular weight in the range from 50 to 650.
4. The method of claim 1 , wherein the resultant ester has a kinematic viscosity at 100° C. of 1500 to 3500 mm 2 /s.
5. The method of claim 1 , wherein the resultant ester has an NPI value of at least 900.
6. The method of claim 1 , wherein the resultant ester has an average molecular weight of at least 3000.
7. The method of claim 1 , wherein the engine oil further comprises a phosphorus-containing and/or sulphur-containing antiwear additive.
8. The method of claim 1 , wherein the engine oil further comprises both a phosphorus-containing and sulphur-containing additive.
9. The method of claim 1 , wherein the engine oil further comprises zinc dialkyl dithiophosphate.
10. The method of claim 1 , wherein the at least one polyfunctional alcohol is neopentylglycol; and the component (c) is azelaic acid.
11. The method of claim 1 , wherein the resultant ester has a kinematic viscosity at 100° C. of 1500 to 4000 mm 2 /s.
12. The method of claim 1 , wherein the resultant ester further comprises an aliphatic monofunctional alcohol having 5 to 24 carbon atoms.
13. A method of reducing wear in an automotive engine by the addition to the engine an automotive engine oil comprising a base oil and an ester which is the reaction product of:
(a) at least one polyfunctional alcohol;
(b) a dimer fatty acid; and
(c) at least an aliphatic dicarboxylic acid having 5 to 18 carbon atoms;
wherein the resultant ester having a kinematic viscosity at 100° C. ranging from 1500 to 5000 mm 2 /s and a non-polarity index (NPI)
NPI
=
total
number
of
carbon
atoms
×
molecular
weight
number
of
carboxylate
groups
×
100
of at least 500; and
wherein the automotive engine oil has a phosphorus level of no more than 0.08%.