Solvent dewaxing waxy bright stock using a combination polydialkyl

Abstract

It has been discovered that (a) poly di alkyl fumarate/vinyl acetate copolymers in combination with (B) poly alkyl (meth-) acrylate polymers are effective dewaxing aids for the solvent dewaxing of bright stocks. The poly di alkyl fumarate/vinyl acetate copolymer component of the combination dewaxing aid used in the process of the present invention has a number average molecular weight of about 1000 to 100,000 and possesses alkyl side chain moieties of from C.sub.16 -C.sub.24.sup.+ in length (excluding branching) with a pendent side chain length of predominantly (>50%) C.sub.20. The polyalkyl (meth-) acrylate is the polymeric ester of aliphatic alcohols having groups 10 to 20 carbons in length, excluding branching (pendent side chain length predominantly (>50%) C.sub.14 and lower) and acrylic or (meth-) acrylic acid (preferably methacrylic acid) and possesses a number average molecular weight of at least 5,000. The solvent dewaxing processes benefitted by the use of the present combination are those using standard normally liquid solvents such as C.sub.3 -C.sub.6 ketones, aromatic hydrocarbons, halogenated hydrocarbons and mixtures thereof. The waxy hydrocarbon oil dewaxed is a bright stock. The dewaxing aid combination may be used at dose level of from about 0.005 to 5 wt. % active ingredient at a component A/B ratio of about 4/1 to 1/100, preferably about 1/1 to 1/20, and most preferably about 1/3.