Multifunctional cooling additives for middle distillates, having an improved flow capability

1. A cold additive for middle distillates comprising

A) at least one polyester of the formula (A1

in which

one of the R 1 to R 4 radicals is a linear C 16 -C 40 -alkyl or -alkenyl radical and the rest of the R 1 to R 4 radicals are each independently hydrogen or an alkyl radical having 1 to 3 carbon atoms,

R 5 is a C—C bond or an alkylene radical having 1 to 6 carbon atoms,

R 16 is a hydrocarbyl group having 2 to 10 carbon atoms,

n is a number from 2 to 100,

m is a number from 5 to 150,

p is 0 or 1, and

q is 0 or 1,

B) at least one copolymer of ethylene and at least one ethylenically unsaturated ester, wherein the copolymer has a melt viscosity measured at 140° C. of not more than 5000 mPas and

C) at least one organic solvent.

2. The cold additive as claimed in claim 1 , in which R 1 is a C 16 - to C 40 -alkyl or -alkenyl radical, R 2 , R 3 and R 4 are each hydrogen and R 5 is a single bond.

3. The cold additive as claimed in claim 1 , in which R 16 is an ethylene group.

4. The cold additive as claimed in claim 1 , in which R 16 is a C 2 - to C 4 -alkylene group and n is a number from 2 to 100.

5. The cold additive as claimed in claim 1 , wherein copolymer B) is a copolymer of ethylene and 8 to 21 mol % of at least one olefinically unsaturated compound selected from the group consisting of vinyl esters, acrylic esters and methacrylic esters.

6. The cold additive as claimed in claim 1 , wherein the solvent C) is selected from the group consisting of aliphatic hydrocarbons having 9 to 20 carbon atoms and aromatic hydrocarbons having 7 to 20 carbon atoms.

7. The cold additive as claimed in claim 1 , wherein the solvent C) additionally comprises a solubilizer which contains 4 to 24 carbon atoms and is selected from the group consisting of alcohols, organic acids, ethers of organic acids, esters of organic acids and mixtures thereof.

8. The cold additive as claimed in claim 1 , comprising 0.1 to 50% by weight of A), 1.5 to 73.5% by weight of B) and 25 to 95% by weight of C).

9. The cold additive as claimed in claim 1 , further comprising at least one further cold flow improver, selected from the group consisting of

III) oil-soluble polar nitrogen compounds,

IV) resins of phenol derivatives bearing alkyl radicals with aldehydes,

V) comb polymers of the formula

in which

A is R′, COOR′, OCOR′, R″—COOR′, OR′;

D is H, CH 3 , A or R″;

E is H, A;

G is H, R″, R″—COOR′, an aryl radical or a heterocyclic radical;

M is H, COOR″, OCOR″, OR″, COOH;

N is H, R″, COOR″, OCOR, an aryl radical;

R′ is a hydrocarbyl chain having 8 to 50 carbon atoms;

R″ is a hydrocarbyl chain having 1 to 10 carbon atoms;

a is a number between 0.4 and 1.0; and

b is a number between 0 and 0.6,

VI) homo- and copolymers of olefins having 2 to 30 carbon atoms, and

VII) esters, ethers and ester/ethers of alkoxylated polyols, which have at least one alkyl radical having 12 to 30 carbon atoms.

10. A process for improving the cold flow properties of fuel oils, comprising the step of adding a cold additive as claimed in claim 1 to a middle distillate.

11. A fuel oil comprising a middle distillate and at least one cold additive as claimed in claim 1 .

12. The fuel oil as claimed in claim 11 , in which the middle distillate has more than 4% by weight of constituents with an n-alkyl chain having 16 or more carbon atoms, wherein the constituents are selected from the group consisting of n-paraffins of fossil origin, n-paraffins prepared by hxydrogenation or cohydrogenation of animal and/or vegetable fats, and esters of saturated fatty acids with lower alcohols.

13. The fuel oil as claimed in claim 11 , in which the middle distillate has a proportion of long-chain n-paraffins having 28 or more carbon atoms of less than 1% by weight.