Coating compositions and coatings produced therefrom with improved soiling resistance and (self-)cleaning properties and use thereof

1. A nonaqueous coating composition comprising:

(A) at least one hydroxyl group-containing compound (A) having a hydroxyl number of 100 to 400 mg KOH/g and a Tg>−35° C., which is present at not less than 25 wt %, based on the binder fraction of the coating composition,

(B) at least one isocyanate group-containing compound (B) having free or blocked isocyanate groups, compound (B) comprising at least one structural unit of the formula (I)

—NR—(X—SiR″ x (OR′) 3-x )  (I),

and/or at least one structural unit of the formula (II),

—N(X—SiR″ x (OR′) 3-x ) n (X′—SiR″ y (OR′) 3-y ) m   (II),

where

R=hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups, with Ra=alkyl, cycloalkyl, aryl, or aralkyl,

R′=hydrogen, alkyl, or cycloalkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups,

X, X′=linear and/or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms,

R”=alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups,

n=0 to 2, m=0 to 2, m+n=2, and x, y=0 to 2,

and

(C) at least one catalyst (C) for the crosslinking of silane groups,

wherein additionally there is

(D) at least one alkoxysilyl-functional siloxane of the formula (III)

R 1 —SiR 2 2 -A x -B y —O—SiR 3 2 —R 4   (III)

in which

A is a group —[O—SiR 5 2 ]— and B is a group —[O—SiR 6 R 7 ]—,

R 2 , R 3 , R 5 , and R 6 independently of one another are linear or branched alkyl groups having 1 to 4 carbon atoms,

R 1 , R 4 , and R 7 independently of one another are a group -L-R 8 ,

in which L=a linear or branched divalent alkyl group and

R 8 =H or —Si(R 9 ) z (OR 10 ) 3-z with R 9 , R 10 =a linear or branched alkyl group having 1-4 carbon atoms and z=0, 1, or 2,

with the proviso that at least one of the radicals R 1 or R 4 and/or at least one group B constitutes a group R 8 =—Si(R 9 ) z (OR 10 ) 3-z ,

x independently is an integer of 1-20,

y independently is an integer of 0-10.

2. The coating composition as claimed in claim 1 , which is a two-component coating composition, wherein the alkoxysilyl-functional siloxane (D) and compound (A) are comprised in the same component.

3. The coating composition as claimed in claim 1 , wherein R 2 , R 3 , and R 5 independently of one another are a methyl and/or ethyl,

R 1 and R 4 independently of one another are a group -L-R 8 , in which L=a linear or branched divalent alkyl group, and R 8 =—Si(R 9 ) z (OR 10 ) 3-z with R 9 , R 10 =a linear or branched alkyl group having 1-4 carbon atoms and z=0, 1, or 2,

and y=0.

4. The coating composition as claimed in claim 3 , wherein the divalent alkyl group is ethylene.

5. The coating composition as claimed in claim 1 , containing no fluorine-containing compounds which lead to hydrophobation of the coating resulting therefrom.

6. The coating composition as claimed in claim 1 , comprising as polyhydroxyl group-containing compound (A) at least one poly(meth)acrylate resin having an OH number of 100 to 300 mg KOH/g, and a glass transition temperature of −35 to 100° C., (measured by means of DSC measurements in accordance with DIN EN ISO 11357-2).

7. The coating composition as claimed in claim 6 , wherein the at least one poly(meth)acrylate resin has an OH number of 150 to 200 mg KOH/g.

8. The coating composition as claimed in claim 1 , comprising at least one phosphorus- and nitrogen-containing catalyst (C).

9. The coating composition as claimed in claim 1 , wherein the compound (B) has been prepared by reacting polyisocyanates and/or their isocyanurate trimers and/or their allophanate dimers and/or their biuret dimers and/or uretdione dimers with at least one compound of the formula (Ia)

H—NR—(X—SiR″ x (OR′) 3-x )  (Ia)

and/or at least one compound of the formula (IIa),

HN(X—SiR″(OR′) 3-x ) n (X′—SiR″ y (OR′) 3-y ) m   (IIa),

where the substituents have the definition stated in claim 1 .

10. A method for producing coatings by applying to an optionally precoated substrate the coating composition as claimed in claim 1 .

11. The method as claimed in claim 10 , which is used for producing a coating for automotive OEM finishing, the finishing of parts for installation in or on automobiles, and/or the finishing of commercial vehicles, and or automotive refinishing.

12. A coating produced by a method as claimed in claim 10 .

13. The coating as claimed in claim 12 , which possesses a glass transition temperature (Tg)>70° C. and a crosslinking density>3.0×10 7 Pa.

14. A method for producing coatings, wherein a pigmented basecoat material and thereafter the coating composition as claimed in claim 1 are applied to an optionally pretreated and optionally precoated substrate.

15. The method as claimed in claim 14 , wherein following application of the pigmented basecoat, the applied basecoat material is first dried at temperatures of 20 to 80° C. and, following application of a nonaqueous coating composition comprising:

(A) at least one hydroxyl group-containing compound (A) having a hydroxyl number of 100 to 400 mg KOH/g and a Tg>−35° C., which is present at not less than 25 wt %, based on the binder fraction of the coating composition,

(B) at least one isocyanate group-containing compound (B) having free or blocked isocyanate groups, compound (B) comprising at least one structural unit of the formula (I)

—NR—(X—SiR″ x (OR′) 3-x )  (I),

and/or at least one structural unit of the formula (II),

—N(X—SiR″ x (OR′) 3-x ) n (X′—SiR″ y (OR′) 3-y ) m   (II),

where

R=hydrogen, alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups, with Ra=alkyl, cycloalkyl, aryl, or aralkyl,

R′=hydrogen, alkyl, or cycloalkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups,

X, X′=linear and/or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms,

R″=alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur, or NRa groups,

n=0 to 2, m=0 to 2, m+n=2, and x, y=0 to 2,

and

(C) at least one catalyst (C) for the crosslinking of silane groups,

wherein additionally there is

(D) at least one alkoxysilyl-functional siloxane of the formula (III)

R 1 —SiR 2 2 -A x -B y —O—SiR 3 2 —R 4   (III)

in which

A is a group —[O—SiR 5 2 ]—and B is a group —[O—SiR 6 R 7 ]—,

R 2 , R 3 , R 5 , and R 6 independently of one another are linear or branched alkyl groups having 1 to 4 carbon atoms,

R 1 , R 4 , and R 7 independently of one another are a group -L-R 8 ,

in which L=a linear or branched divalent alkyl group and

R 8 =H or —Si(R 9 ) z (OR 10 ) 3-z with R 9 , R 10 =a linear or branched alkyl group having 1-4 carbon atoms and z=0, 1, or 2,

with the proviso that at least one of the radicals R 1 or R 4 and/or at least one group B constitutes a group R 8 =—Si(R 9 ) z (OR 10 ) 3-z ,

x independently is an integer of 1-20,

y independently is an integer of 0-10,

is cured at temperatures of 20 to 200° C. during a time of one minute up to 10 hours.

16. A method of improving the soiling resistance and the (self-)cleaning properties of coatings by applying the coating composition as claimed in claim 1 .

17. The coating as claimed in claim 12 , which possesses a soiling resistance of ΔL* 1-2 <30, where ΔL* 1-2 defines the difference in the colorimetric lightness L* before (L* 1 ) and after (L* 2 ) soiling of a sample panel on which the coating composition has been applied and cured.

18. A multicoat effect and/or color coating comprising at least one pigmented basecoat and at least one clearcoat disposed thereon, wherein the clearcoat has been produced from the coating composition as claimed in claim 1 .

19. The coating composition as claimed in claim 1 , wherein, in formula (III), x+y≤20.