Cold flow improver

Claim 2

A polymer which is effective in lowering the cold flow temperature of middle distillate fuel, said polymer containing (a) 50 to 90 weight percent of units having the structure ―CH 2 CH 2 ―, (b) 10 to 40 weight percent of units having the structure wherein R is selected from the group consisting of hydrogen and aliphatic hydrocarbon groups containing 1-11 carbon atoms, (c) 0.2 to 10 weight percent of units having the structure wherein R 2 is an aliphatic hydrocarbon group containing 1-28 carbon atoms and (d) 1 to 30 weight percent of units having the structure wherein R 3 is selected from the group consisting of hydrogen and methyl and R 4 is selected from the group consisting of hydrogen and aliphatic hydrocarbons containing 1-30 carbon atoms, said polymer having a number average molecular weight of 1,000-10,000.

Claim 3

2 . A polymer of Claim 1 wherein R1 is an alkyl group of 1-4 carbon atoms.

Claim 4

A polymer of Claim 2 wherein R 2 is an aliphatic hydrocarbon group of 1-10 carbon atoms.

Claim 5

A polymer of Claim 3 wherein R 3 and R 4 are hydrogen.

Claim 6

A polymer of Claim 2 wherein R 1 is methyl.

Claim 7

A polymer of Claim 5 wherein R is n-butyl.

Claim 8

A polymer of Claim 6 having a number average molecular weight of 2,000 to 5,000.

Claim 9

A process for making a polymer of Claim 1 which is an effective cold flow improver in middle distillate fuel said process comprising polymerizing: (a) ethylene, (b) an olefin containing 3-30 carbon atoms, (c) a vinyl ester of a fatty acid containing 1-12 carbon atoms and, (d) a vinyl substituted aromatic hydrocarbon selected from the group consisting of styrene, alpha-methyl styrene and nuclear substituted derivatives thereof wherein the nuclear substituents are aliphatic hydrocarbon groups containing 1-30 carbon atoms in an inert solvent at a pressure sufficient to maintain a liquid phase at a polymerization temperature of 80 to 200°C in the presence of a catalytic amount of a free-radical generating catalyst.

Claim 10

A process of Claim 8 which comprises polymerizing: (a) 50 to 90 parts by weight of ethylene, (b) 0.2 to 10 parts by weight of a linear alpha-olefin containing 3-30 carbon atoms, (c) 10 to 40 parts by weight of vinyl acetate and (d) 1 to 30 parts by weight of styrene.

Claim 11

A process of Claim 9 which comprises (a) forming a mixture of 1 to 20 weight percent linear alpha-olefin containing 3-12 carbon atoms, 50 to 90 weight percent vinyl acetate and 1 to 49 weight percent styrene to form a comonomer mixture (b) forming a solution of a free-radical generating catalyst in an inert hydrocarbon solvent to form a catalyst solution (c) pressurizing a reaction vessel with ethylene to an ethylene pressure of 700 to 2,000 psig (49.277 to 138.909 Bars). (d) simultaneously feeding said comonomer mixture and said catalyst solution to. said reaction vessel while adding ethylene sufficient to maintain a pressure of 700 to 2,000 psig (49.277 to 138.909 Bars) and reacting said comonomer mixture and said ethylene at a temperature of 100 to 150°C until the average number molecular weight of the resultant polymer is 2,000 to 5,000.

Claim 12

A process of Claim 9 wherein said linear alpha-olefin is alpha-hexene.

Claim 13

A distillate petroleum fuel containing 0.02 to 0.20 weight percent of a polymer of Claims 1 to 7.