Use of partially silanized polyisocyanate-based compounds as crosslinking-agents in coating compositions, and coating compositions comprising the compounds
The invention relates to the use of partly silanized compounds based on polyisocyanate as crosslinking agents with heightened refractive index in curable coating compositions, more particularly in clearcoat materials for automotive finishing. The invention likewise relates to a coating composition which comprises these compounds as crosslinking agents, and to the use of the coating composition to produce a coating.
1. A method of crosslinking a coating composition, comprising using a compound (V) as a crosslinking agent in a curable coating composition, the compound (V) being the reaction product of at least one isocyanate compound (A) having an average NCO functionality of 2.0 to 6.0, with at least one compound of the general formula (I)
where m is 2, 3 or 4; and
R 1 , R 2 , and R 3 , independently of one another, are each H, unsubstituted or at least monosubstituted alkyl or unsubstituted or at least monosubstituted heteroalkyl, and
from between 0.1% and 20% by weight, based on the nonvolatile constituents of the coating composition, of an amine-blocked phosphoric acid as a crosslinking catalyst;
wherein from 0.1 to 99 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with the at least one compound of the general formula (I).
2. The method of claim 1 , wherein 5 to 95 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with the at least one compound of the general formula (I).
3. The method of claim 1 , wherein m is 2, 3 or 4; and
R 1 , R 2 , and R 3 , independently of one another, are each H, unsubstituted C 1-12 alkyl or unsubstituted 2- to 12-membered heteroalkyl.
4. The method of claim 3 ,
wherein m is 3; and
R 1 , R 2 , and R 3 , independently of one another, are each H, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso butyl, 2-butyl, tert-butyl, n-pentyl, 2-pentyl, iso-pentyl or neopentyl.
5. The method of claim 4 ,
wherein m is 3; and
R 1 , R 2 , R 3 , independently of one another, are each ethyl or methyl.
6. The method of claim 1 , wherein the isocyanate compound (A) is a polyisocyanate derived from a polyisocyanate by trimerization, dimerization, urethanization, biuretization or allophanatization.
7. The method of claim 6 , wherein the derived polyisocyanate is based on a parent structure selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, and (4,4′)-methylenedicyclohexyl diisocyanate.
8. A coating composition comprising
at least one binder,
at least one solvent,
at least one crosslinking agent comprising a compound (V) based on
at least one isocyanate compound (A) having an average NCO functionality of 2.0 to 6.0, wherein 0.1 to 99 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with at least one compound of the general formula (I)
wherein m is 2, 3 or 4; and
R 1 , R 2 , R 3 , independently of one another, are each H, unsubstituted or at least monosubstituted alkyl or unsubstituted or at least monosubstituted heteroalkyl; and
from between 0.1% and 20% by weight, based on the nonvolatile constituents of the coating composition, of a catalyst that is an amine-blocked phosphoric acid.
9. The coating composition of claim 8 , wherein at least one binder is a hydroxyl compound (B).
10. The coating composition of claim 9 , wherein the hydroxyl compound (B) is at least one of a low molecular mass polyol, an oligomeric polyol, a polymeric polyol or a mixture of these polyols.
11. The coating composition of claim 10 , wherein the polymeric polyol is a poly(meth)acrylate polyol.
12. The coating composition of claim 8 , that is a clearcoat material.
13. A method of coating a substrate, comprising applying to a substrate, the coating composition of claim 8 to produce a coating.
14. The method of claim 2 , wherein 10 to 90 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with the at least one compound of the general formula (I).
15. The method of claim 14 , wherein 20 to 80 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with the at least one compound of the general formula (I).
16. The coating composition of claim 8 ,
wherein m is 3; and
R 1 , R 2 , and R 3 , independently of one another, are each H, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso butyl, 2-butyl, tert-butyl, n-pentyl, 2-pentyl, iso-pentyl or neopentyl.
17. The coating composition of claim 16 ,
wherein m is 3; and
R 1 , R 2 , R 3 , independently of one another, are each ethyl or methyl.
18. The coating composition of claim 8 , wherein the derived polyisocyanate is based on a parent structure selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, and (4,4′)-methylenedicyclohexyl diisocyanate.
19. The coating composition of claim 8 , wherein 5 to 95 mol % of the isocyanate groups originally present in the isocyanate compound (A) have been reacted with the at least one compound of the general formula (I).
20. The method of claim 1 , wherein the crosslinking catalyst is an amine-blocked acyclic phosphoric diester or an amine-blocked cyclic phosphoric diester.
21. The method of claim 20 , wherein the crosslinking catalyst is an amine-blocked phosphoric acid ethylhexyl ester or an amine-blocked phosphoric acid phenyl ester.
22. The coating composition of claim 8 , wherein the crosslinking catalyst is an amine-blocked acyclic phosphoric diester or an amine-blocked cyclic phosphoric diester.
23. The coating composition of claim 22 , wherein the crosslinking catalyst is an amine-blocked phosphoric acid ethylhexyl ester or an amine-blocked phosphoric acid phenyl ester.
24. The method of claim 1 , wherein the compound (V) has a refractive index of nD20>1.500 at a temperature of 20° C.
25. The coating composition of claim 8 , wherein the compound (V) has a refractive index of nD20>1.500 at a temperature of 20° C.