Crosslinkable composition crosslinkable with a latent base catalyst
The present invention relates to a crosslinkable composition comprising at least one crosslinkable component and a latent base crosslinking catalyst, which crosslinkable composition has a solids content of typically at least 55 wt (dry weight after crosslinking relative to the total weight of the crosslinking composition) wherein the latent base catalyst is a substituted carbonate salt according to formula 1 wherein X + represents a non acidic cation, preferably a quaternary ammonium or phosphonium, and wherein R is hydrogen, alkyl, aryl or aralkyl group.
1. A crosslinkable composition comprising a base crosslinking catalyst and reactive components A, A2 and B, wherein A and B each comprising at least 2 reactive groups wherein the at least 2 reactive groups of component A are acidic protons (C—H) in activated methylene or methine groups and the at least 2 reactive groups of component B are activated unsaturated groups (C═C) to achieve crosslinking by Real Michael Addition (RMA) reaction, wherein the component A2 comprises reactive acidic protons, and wherein A2 has a higher acidity than component A and is reactive towards component B with an RMA reaction.
2. The crosslinkable composition according to claim 1 , wherein the activated C—H group in component A is a malonate or acetoacetate.
3. The crosslinkable composition according to claim 1 , wherein the component A comprises an average of 2 to 20 active C—H functions per molecule.
4. The crosslinkable composition according to claim 1 , wherein the component B comprises an unsaturated acryloyl or maleate functional group.
5. The crosslinkable composition according to claim 1 , wherein component A is a polymer selected from the group consisting of polyester, polyurethane, acrylic, polycarbonate or a mixture/hybrid of these and B is an unsaturated acryloyl functional component.
6. The crosslinkable composition according to claim 1 , wherein the ratio of the number of activated reactive acidic protons (C—H) in component A to the number of activated unsaturated groups (C═C) on component B is in the range between 10 and 0.1.
7. The crosslinkable composition according to claim 1 , wherein A is malonate and A2 is a component according to formula 2 :
wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and Y and Y′ are same or different substituent groups selected from a group consisting of alkyl, aralkyl, aryl (R*), and alkoxy (—OR*), or wherein the —C(═O)—Y and/or —C(═O)—Y′ is replaced by CN or phenyl.
8. The crosslinkable composition according to claim 1 , wherein pKa of component A2 is between 0.5 and 6 units lower than pKa of component A.
9. A crosslinkable composition according to claim 1 , wherein the component A2 comprising C—H acidic protons in activated methylene or methine groups.
10. The crosslinkable composition according to claim 9 , wherein the amount of activated C—H in methine or methylene functional groups of the component A2 is between 0.1 and 50 mole of the total mole of activated C—H in methine or methylene functional groups.
11. The crosslinkable composition according to claim 1 , wherein component A is a malonate containing component and component A2 is an acetoacetate or acetylacetone containing component.
12. The crosslinkable composition according to claim 1 , wherein the C—H functionality of component A2 is lower than the C—H functionality of A, C—H functionality being defined as the average number of active C—H per molecule A or A2.
13. The crosslinkable composition according to claim 1 having a solids content of at least 55 wt %, wherein the solids content is dry weight after crosslinking relative to the total weight of the composition.
14. A coating composition comprising the crosslinkable composition according to claim 1 .
15. The crosslinkable composition according to claim 3 , wherein the component A comprises 4 to 10 active C—H functions per molecule.
16. The crosslinkable composition according to claim 1 , wherein the C—H functionality of A2 is 2-4.