Polyalkylene glycol lubricant compositions

A hydrocarbon lubricant composition comprised of,

• (i) an antioxidant;
• (ii) an esterified polyalkylene glycol:
• R1[O(R2O)n(R3O)m(C═O)R4]p
• wherein R1 is a linear alkyl having 1 to 18 carbon atoms, a branched alkyl having 4 to 18 carbon atoms or an aryl with 6 to 30 carbon atoms;
• R2O is an oxypropylene moiety derived from 1,2-propylene oxide;
• R3O is an oxybutylene moiety derived from butylene oxide, wherein R2O and R3O are in a block or a random distribution;
• R4 is a linear alkyl with 1 to 18 carbon atoms, a branched alkyl with 4 to 18 carbon atoms or an aryl with 6 to 18 carbon atoms;
• n and m are each independently integers ranging from 2 to 10, and p is an integer from 1 to 4;
• and
• (iii) a hydrocarbon base oil, wherein the antioxidant is present in an amount by weight of at least 0.1% to 10% based upon the weight of the hydrocarbon lubricant composition and the antioxidant is soluble in the esterified polyalkylene glycol in an amount of at least 0.5% by weight and the hydrocarbon oil is present in the composition in an amount of at least 50% by weight of the total weight of the hydrocarbon lubricant composition.

A method of forming a hydrocarbon lubricant composition comprising:

• (i) dissolving, first, an antioxidant into an esterified polyalkylene glycol represented by the following structure:
• R1[O(R2O)n(R3O)m(C═O)R4]p
• wherein R1 is a linear alkyl having 1 to 18 carbon atoms, a branched alkyl having 4 to 18 carbon atoms or an aryl with 6 to 30 carbon atoms;
• R2O is an oxypropylene moiety derived from 1,2-propylene oxide;
• R3O is an oxybutylene moiety derived from butylene oxide, wherein R2O and R3O are in a block or a random distribution;
• R4 is a linear alkyl with 1 to 18 carbon atoms, a branched alkyl with 4 to 18 carbon atoms or an aryl with 6 to 18 carbon atoms;
• n and m are each independently integers ranging from 2 to 10, and p is an integer from 1 to 4, to form a solution of the antioxidant and esterified polyalkylene glycol, and then
• (ii) admixing a base hydrocarbon oil with the solution of the antioxidant and esterified polyalkylene glycol to form the hydrocarbon lubricant composition, wherein said hydrocarbon lubricant composition is a homogeneous solution.