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

An aqueous polymer dispersion comprising water and further comprising

• a) 10 to 55% 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 comprise
• 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;
• 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 75 nm to 400 nm effected by Column Hydrodynamic Chromatography;
• b) 0 to 24.5% by weight based on the total amount of the aqueous polymer dispersion of at least one miscible solvent,
• c) 5 to 30% by weight based on the total amount of the aqueous polymer dispersion of at least one hydrophobic organic solvent,
• d) 10 to 30% by weight based on the total amount of monomers M of at least one protective colloid, wherein the at least one protective colloid is a polymer obtained by the reaction of
• 15 to 40% by weight of acrylic acid, methacrylic acid, or a mixture thereof;
• and
• 60 to 85% by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or a mixture of two or more thereof,
• wherein the given amounts are each based on the total amount of the at least one protective colloid;
• and
• e) 0 to 5% by weight based on the total amount of the aqueous polymer dispersion of at least one surfactant.