| 摘要 |
The invention relates to additives for improving the cold flow properties of middle distillates, containing from 10 to 95% by weight of copolymers A), from 5 to 90% by weight of copolymers B) and, if required, from 0 to 70% by weight of copolymers C), which correspond to the following formulae:A) copolymers of lower olefins and vinyl esters,B) copolymers comprisingB1) from 40 to 60 mol % of bivalent structural units of the formula where X is O or N-R4 and in which a and b are 0 or 1 and a +b=1, andB2) from 60 to 40 mol % of bivalent structural units of the formulaand, if required,B3) from 0 to 20 mol % of bivalent structural units which are derived from polyolefins, the polyolefins being derivable from monoolefins having 3 to 5 carbon atoms, and in which a) R4 is an alkyl or alkenyl radical having 10 to 40 carbon atoms or an alkoxyalkyl radical having 1 to 100 alkoxy units and 1 to 30 carbon atoms in the alkyl radical, and b) R5 is a radical of the formula OCOR12 or COOR12, in which R12 is C1-to C3-alkyl, and c) the number of carbon atoms of the polyolefin molecules on which the structural units B3) are based is from 35 to 350, and d) R11 is hydrogen or methyl, and, if required,C) a further copolymer differing from A) and B) and comprising ethylene and one or more vinyl esters or acrylates, which by itself is effective as a cold flow improver for middle distillates.
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