Aryl-PAG monoesters as lubricating oil base stocks
The present invention discloses aryl-polyalkylene glycol monoester compound compositions that are suitable for use as a base oil, particularly a base oil for use as an automotive lubricant. The compositions can generally be characterized by having low kinematic viscosity at 100° C. high viscosity index and low Noack volatility. The present invention also discloses lubricant formulations including such aryl-polyalkylene glycol monoester compounds with other materials such as an API Group I-V base oil and/or additives.
1 . A composition comprising an aryl-PAG monoester compound represented by the formula:
R 1 O-(AO) n -(C═O)—R x —R 2
where: R 1 is a linear or branched alkyl or aryl with 1 to 18 carbon atoms;
AO refers to a 1,2-alkylene oxide or mixture thereof in a random or block feeding order;
n is an integer from 1 to 10;
R x is a linear or branched alkyl with 0 to 18 carbon atoms; and
R 2 is an aryl group, heteroaryl group, or arylalkyl group with 4 to 18 carbon atoms, any of which may optionally include oxygen or nitrogen or sulfur atoms.
2 . The composition of claim 1 where n is selected to provide a target kinematic viscosity at 100° C. of less than 6 cSt.
3 . The composition of claim 1 wherein R 1 is a linear or branched alkyl with 1 to 12 carbon atoms.
4 . The composition of claim 1 where the 1,2-alkylene oxide is selected from the group consisting of ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, and mixtures thereof.
5 . The composition of claim 1 wherein R x is a linear alkyl with 0 to 6 carbon atoms.
6 . The composition of claim 1 wherein R 2 is an aryl or arylalkyl group with 6 to 12 carbon atoms.
7 . The composition of claim 1 wherein R 2 has from 1 to 3 aryl rings.
8 . The composition of claim 1 characterized in that it has a kinematic viscosity at 100° C. as determined according to ASTM D445 of from 2 cSt, up to 6 cSt.
9 . The composition of claim 1 characterized in that it has a Noack volatility as determined according to ASTM D6375 of less than 45%.
10 . The composition of claim 1 characterized in that it has a pour point as determined by ASTM D97 of less than −40° C.
11 . The composition of claim 1 characterized in that it has a kinematic viscosity at 100° C. as determined according to ASTM D445 of from 2 cSt up to 6 cSt, a Noack volatility as determined according to ASTM D6375 of less than 45%, and a pour point as determined by ASTM D97 of less than −40° C.
12 . A lubricant formulation comprising a base oil which is an aryl-PAG monoester compound represented by the formula:
R 1 O-(AO) n -(C═O)—R x —R 2
where: R 1 is a linear or branched alkyl or aryl with 1 to 18 carbon atoms;
AO refers to a 1,2-alkylene oxide or mixture thereof in a random or block feeding order;
n is an integer from 1 to 10;
R x is a linear or branched alkyl with 0 to 18 carbon atoms; and
R 2 is an aryl group, heteroaryl group, or arylalkyl group with 4 to 18 carbon atoms, any of which may optionally include oxygen or nitrogen or sulfur atoms.
13 . The lubricant formulation of claim 12 further comprising one or more additional base oils where such additional base oil is an API Group I-V base oil.
14 . The lubricant formulation of claim 13 , where the additional base oil has a kinematic viscosity at 100° C. as determined according to ASTM D445 of from 2 cSt, up to 6 cSt.
15 . The lubricant formulation of claim 12 further comprising anti-wear agents, rust preventatives, metal deactivators, anti-hydrolysis agents, anti-static agents, defoamers, antioxidants, dispersants, detergents, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, tackifiers, metallic detergents, ashless dispersants and corrosion inhibitors.