Polyisocyanate mixtures, a process for their preparation and their use in coating compositions
The present invention relates to polyacrylate-modified polyisocyanates which are i) prepared from aromatic, araliphatic, cycloaliphatic and/or aliphatic polyisocyanates having an NCO content of 5% to 25% by weight, an NCO functionality ≧2, a viscosity measured as solvent free resin of 150 to 200,000 mPa·s at 23° C., and ii) contain at least one structural unit of the formula (I) wherein R is hydrogen or a methyl group, R 1 is an optionally heteroatom-containing hydrocarbon radical and R 2 is a hydrocarbon radical having at least one isocyanate group and optionally urethane, allophanate, biuret, uretdione, isocyanurate and/or iminooxadiazinedione groups and n ist a number ≧1. The present invention also relates to a process for preparing these polyisocyanates and to binder compositions containing these polyisocyanates, which may be hydrophilically modified, and a compound having NCO-reactive groups.
1 . A polyacrylate-modified polyisocyanate which is i) prepared from an aromatic, araliphatic, cycloaliphatic and/or aliphatic polyisocyanate having an NCO content of 5% to 25% by weight, an NCO functionality≧2 and a viscosity measured as solvent free resin of 150 to 200,000 mPa·s at 23° C., and ii) contains at least one structural unit of the formula (I)
where
R is hydrogen or a methyl group,
R 1 is an optionally heteroatom-containing hydrocarbon radical and
R 2 is a hydrocarbon radical having at least one isocyanate group and optionally a urethane, allophanate, biuret, uretdione, isocyanurate or iminooxadiazinedione group and
n is a number ≧1.
2 . The polyacrylate-modified polyisocyanate of claim 1 wherein R 2 contains at least one urethane, allophanate, biuret, uretdione, isocyanurate and/or iminooxadiazinedione group.
3 . A process for preparing the polyacrylate-modified polyisocyanate of claim 1 which comprises reacting a portion of the isocyanate groups of
A) a starting polyisocyanate with
B) a monoalcohol containing acrylate and/or methacrylate groups, to form urethane groups, and subsequently to or simultaneously with the urethanization, reacting the unsaturated groups of the resulting reaction product by free-radically initiated polymerization optionally with
C) other unsaturated monomers.
4 . The process of claim 3 wherein starting polyisocyanate A) comprises a polyisocyanate containing a urethane, uretdione, allophanate, biuret, isocyanurate or iminooxadiazinedione group and exclusively containing aliphatically and/or cycloaliphatically bound NCO groups.
5 . A polyurethane and/or polyurea prepared from the polyacrylate-modified polyisocyanate of claim 1 .
6 . A coating, adhesive, or sealant composition comprising the polyacrylate-modified polyisocyanate of claim 1 .
7 . A substrate coated with the coating composition of claim 6 .
8 . A binder composition comprising the polyacrylate-modified polyisocyanate of claim 1 , wherein optionally some or all of whose NCO groups have been blocked, and a compound having NCO-reactive groups.