Dispersion comprising hydrophobized silicon dioxide particles, and paint preparation

1. An aqueous dispersion, comprising:

50%-80% by weight of water;

10%-30% by weight of hydrophobized silicon dioxide particles;

5%-15% by weight of at least one alcohol alkoxylate of the formula:

R 1 O((CH 2 ) m′ O) n′ H;

0.5%-5% by weight of at least one component selected from the group consisting of an amine and an amino alcohol having a molecular weight of less than 500;

0%-1% by weight of N-methylpyrrolidone;

0.1-1.5% by weight of at least one of polyethylene glycol and polypropylene glycol;

wherein the weight percentages are based on the total weight of the dispersion;

and

0.1-1% by weight, based on the total weight of the hydrophobized silicon dioxide particles, of at least one copolymer of the formula (I):

wherein:

R 1 represents a branched or unbranched alkyl or alkenyl radical comprising 10-25 C atoms;

m′ represents 2 or 3;

n′ represents 10-50;

Z represents:

either M is hydrogen, a mono- or divalent metal cation, an ammonium ion, or an organic amine radical and a is 1, or M is a divalent metal cation and a is 0.5;

X represents: —OM a , —O—(C p H 2p O) q —R 4 , —NHR 2 , or NR 2 2 ;

R 4 represents H, an aliphatic hydrocarbon radical comprising 1 to 20 C atoms, a cycloaliphatic hydrocarbon radical comprising 5 to 8 C atoms, or optionally a substituted aryl radical comprising 6 to 14 C atoms;

p represents 2-4;

q represents 0-100;

R 2 represents R 1 or —CO—NH 2 ;

Y represents O or NR 2 ;

m represents 10-30;

A 1 represents an ethylene radical, a propylene radical, an isopropylene radical, or a butylene radical;

n represents 0-50;

k represents 10-30; and

the sum m+k is in a range of 20-60.

2. The dispersion according to claim 1 , wherein the hydrophobized silicon dioxide particles have a methanol wettability of from 30% to 60% by volume.

3. The dispersion according to claim 1 , wherein the hydrophobized silicon dioxide particles are silanized silicon dioxide particles.

4. The dispersion according to claim 1 , wherein the hydrophobized silicon dioxide particles are of pyrogenic origin.

5. The dispersion according to claim 1 , wherein the hydrophobized silicon dioxide particles have an average particle size d 50 in the dispersion of not more than 300 nm.

6. The dispersion according to claim 1 , wherein the at least one alcohol alkoxylate of the formula R 1 O((CH 2 ) m′ O) n′ H is present in an amount of from 5% to 20% by weight based on the total weight of the hydrophobized silicon dioxide particles.

7. The dispersion according to claim 1 , wherein:

R 1 represents CH 3 (CH 2 ) x CH 2 O such that x=8-18; and

n′ represents 15-25.

8. The dispersion according to claim 1 , wherein the at least one of the amine and amino alcohol is present in an amount of from 3% to 20% by weight, based on the total weight of the hydrophobized silicon dioxide particles.

9. The dispersion according to claim 1 , comprising the amino alcohol.

10. The dispersion according to claim 1 , further comprising:

up to 10% by weight of at least one organic solvent,

wherein the at least one organic solvent is not N-methylpyrrolidone.

11. A paint formulation, comprising the dispersion according to claim 1 .

12. A composition, comprising the dispersion according to claim 1 ,

wherein the composition is

an addition to a water-based primer-surfacer,

a coating constituent, or

an additive in a water-based UV-curable formulation.

13. The dispersion according to claim 5 , wherein the hydrophobized silicon dioxide particles have an average particle size d 50 in the dispersion of from 100 to 250 nm.