Crosslinking component for binder resins
This invention relates to a crosslinking component for binder resins which is especially suitable to be used together with epoxy-group containing binders and/or (poly)isocyanates such as blocked (poly)isocyanates and which comprises at least two blocked isocyanate groups per molecule of the crosslinking component whereby at least one of the at least two blocked isocyanate groups is a group according to structural unit (I), wherein the ratio of structural units of formula (II), if present, to structural units of formula (I) is 0.40 or below. The cross-linking component may also be self-cross-linkable. The present invention further relates to a coating composition, e.g. a one-component coating composition comprising the crosslinking component and a method of its manufacture.
1. A coating composition comprising a crosslinking component comprising at least two blocked isocyanate groups per molecule of the crosslinking component whereby at least one of the at least two blocked isocyanate groups is a group according to the following structural unit (I)
with
R 1 being a C 2 to C 10 hydrocarbyl group,
wherein
the ratio of structural units of the following formula (II), if present,
to structural units of formula (I) is 0.20 or below; and
a binder resin comprising epoxy groups, alpha-beta-unsaturated ester groups, (blocked) isocyanates, keto groups, aldehyde groups or mixtures thereof;
where the structural unit (I) forms a free amine by generating a C—C double bond containing compound originating from R 1 and CO 2 during reaction with the resin.
2. The coating composition according to claim 1 wherein the crosslinking component is substantially free of structural units (II).
3. The coating composition according to claim 1 wherein R 1 is a C 2 to C 10 alkyl group.
4. The coating composition according to claim 1 wherein R 1 is a tert-butyl group.
5. The coating composition according to claim 1 wherein the number average molecular weight of the crosslinking component is within the range of 350 g/mol to 5000 g/mol.
6. The coating composition of claim 1 wherein the binder resin is a binder resin comprising epoxy and/or blocked isocyanate groups.
7. The coating composition of claim 1 being a one-component coating composition.