Low viscosity allophanates containing actinically curable groups
View Patent ↗The present invention relates to a process for preparing radiation-curing binders containing allophanate groups by reacting at temperatures of ≦130° C. A) one or more compounds containing uretdione groups with B) one or more OH-functional compounds which contain groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation (radiation-curing groups), C) optionally NCO-reactive compounds other than B), in the presence of D) a catalyst containing at least one zinc compound, to form allophanate groups by opening the uretdione ring.
1. A process for preparing a radiation-curing binder containing allophanate groups which comprises reacting at temperatures of ≦130° C.
A) one or more compounds containing uretdione groups with
B) one or more OH-functional compounds which contain at least one group selected from vinyl ethers, acrylates and methacrylates which polymerize with ethylenically unsaturated compounds on exposure to actinic radiation,
C) optionally NCO-reactive compounds other than B), in the presence of
D) a catalyst comprising at least one zinc compound, to form allophanate groups by opening the uretdione ring.
2. The process of claim 1 wherein said compounds containing uretdione groups are prepared from hexamethylene diisocyanate.
3. The process of claim 1 wherein component B) comprises 2-hydroxyethyl acrylate and/or 4-hydroxybutyl acrylate.
4. The process of claim 2 wherein component B) comprises 2-hydroxyethyl acrylate and/or 4-hydroxybutyl acrylate.
5. The process of claim 1 wherein component D) consists essentially of zinc compounds.
6. The process of claim 1 wherein component D) comprises zinc acetylacetonate and/or zinc ethylhexanoate.
7. The process of claim 2 wherein component D) comprises zinc acetylacetonate and/or zinc ethylhexanoate.
8. The process of claim 3 wherein component D) comprises zinc acetylacetonate and/or zinc ethylhexanoate.
9. The process of claim 4 wherein component D) comprises zinc acetylacetonate and/or zinc ethylhexanoate.
10. The process of claim 1 wherein the reaction is carried out at a temperature of 40 to 100° C.