Polymeric pour point depressants for waxy crude oils

A method for reducing one or more of pour point, viscosity, yield stress and/or wax deposition of a hydrocarbon oil comprising the step of adding at least one wax inhibitor for hydrocarbon oils comprising an esterified copolymer having repeating structural units derived from an esterified ethylenically unsaturated dicarboxylic acid and at least one α-olefin having at least 18 carbon atoms, whereof at least 3 mol-% of the at least one α-olefin has 30 or more carbon atoms, and wherein the ethylenically unsaturated dicarboxylic acid has been esterified with a mixture of fatty alcohols comprising

• i) 70 to 97 mol-% of a saturated fatty alcohol having 18 to 24 carbon atoms and
• ii) 3 to 30 mol-% of an unsaturated fatty alcohol having 16 to 24 carbon atoms, to the hydrocarbon oil.

A process for manufacturing a wax inhibitor, wherein maleic anhydride and α-olefins having at least 18 carbon atoms, wherein at least 3 mol-% of the α-olefins have 30 or more carbon atoms, are copolymerized in the presence of a free radical chain initiator and the copolymer is subsequently esterified with a mixture of fatty alcohols comprising

• i) 70 to 97 mol-% of a saturated fatty alcohol having 18 to 24 carbon atoms and
• ii) 3 to 30 mol-% of an unsaturated fatty alcohol having 16 to 24 carbon atoms.

A process for manufacturing a wax inhibitor, wherein maleic anhydride is esterified with a mixture of fatty alcohols comprising

• i) 70 to 97 mol-% of a saturated fatty alcohol having 18 to 24 carbon atoms and
• ii) 3 to 30 mol-% of an unsaturated fatty alcohol having 16 to 24 carbon atoms and is subsequently copolymerized in the presence of a radical chain initiator with α-olefins having at least 18 carbon atoms, whereof at least 3 mol-% of the α-olefins have 30 or more carbon atoms.

Method of reducing the pour point and/or the viscosity of a wax inhibitor which is a copolymer having repeating structural units derived from an ethylenically unsaturated dicarboxylic acid or its anhydride and α-olefins having at least 18 carbon atoms, whereof at least 3 mol-% of the α-olefins have 30 or more carbon atoms, wherein prior to esterification of the ethylenically dicarboxylic acid, its anhydride and/or the copolymer with a saturated fatty alcohol having 18 to 24 carbon atoms 70 to 97 mol-% of the saturated fatty alcohol having 18 to 24 carbon atoms is admixed with 3 to 30 mol-% of an unsaturated fatty alcohol having 16 to 24 carbon atoms.