Aqueous polymer dispersions, a method for their preparation and the use thereof as pour-point depressants for crude oil, petroleum, and petroleum products

Aqueous polymer dispersion comprising water and

• a) 10 to 60% by weight based on the dispersion of at least one polymer P obtainable by the reaction of reactive monomers M, wherein the reactive monomers M consist of
• 50 to 100% by weight of at least one monomer M1 of the general formula (I)
• H2C═CH—C(O)OR (I)
• wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms;
• and
• 0 to 50% by weight of at least one monomer M2, which is different from monomer M1 and selected from the group consisting of
• acrylate monomers of the general formula (II),
• H2C═CH—C(O)OR3 (II),
• wherein R3 is a branched or unbranched alkyl chain comprising from 1 to 12 carbon atoms, optionally substituted with a hydroxyl group;
• methacrylate monomers of the general formula (III)
• H2C═C(CH3)—C(O)OR4 (III),
• wherein R4 is a branched or unbranched alkyl chain comprising from 1 to 12 carbon atoms, optionally substituted with a hydroxyl group;
• and
• vinylic aromatic monomers;
• wherein the amounts of the monomers M1 and M2 are each based on the total amount of all reactive monomers M used in the reaction,
• wherein the polymer P has a weight-average molecular weight Mw of 20,000 to 150,000 g/mol according to DIN 55672-1:1995-02;
• and
• wherein the polymer P is present in the form of particles having an average particle size d50 of from 50 nm to 1000 nm effected by Column Hydrodynamic Chromatography;
• b) 5 to 60% by weight based on the total amount of the aqueous polymer dispersion of at least one water miscible solvent,
• c) 5 to 40% by weight based on the total amount of the aqueous polymer dispersion of at least one hydrophobic organic solvent,
• d) 0.1 to 20% by weight based on the total amount of the aqueous polymer dispersion of at least one ionic surfactant.