Method for reversible covalent crosslinking of adhesives
View Patent ↗The present invention relates to a method for thermal crosslinking of adhesives and also to products produced with these adhesives. An object of the invention is to provide a method for thermal crosslinking of adhesives where the crosslinking is covalent and (initiated by a chemical or physical stimulus) reversible. As and when required, the crosslinking method can also be configured to result in a covalent, irreversible network.
1. A crosslinkable adhesive comprising
at least one polymer functionalised with organic and/or inorganic acid units containing OH groups, and at least one cyclic phosphonic anhydride.
2. The crosslinkable adhesive according to claim 1 , wherein the cyclic phosphonic anhydride is a cyclic alkyl phosphonic anhydride.
3. The crosslinkable adhesive according to claim 1 wherein the cyclic phosphonic anhydride is a cyclic 2,4,6-substituted 1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide.
4. The crosslinkable adhesive according to claim 1 wherein the organic and/or inorganic acid units containing OH groups are carboxylic acid groups, maleic acid groups, sulphonic acid groups and/or phosphonic acid groups.
5. The crosslinkable adhesive according to claim 1 wherein the polymers functionalised with organic and/or inorganic acid units containing OH groups are further at least partly functionalised with amino groups, monosubstituted amino groups, bisubstituted amino groups, hydroxyl groups, unsubstituted phenyl radicals, substituted phenyl radicals, 1,3-diketone radicals and/or heteroaromatic compounds.
6. The crosslinkable adhesive according to claim 1 further comprising at least one polymers functionalised with amino groups, monosubstituted amino groups, bisubstituted amino groups, hydroxyl groups, unsubstituted phenyl radicals, substituted phenyl radicals, 1,3-diketone radicals and/or heteroaromatic compounds.
7. The crosslinkable adhesive according to claim 1 wherein crosslinkers are additionally present.
8. The crosslinkable adhesive according to claim 1 wherein the at least one polymer functionalised with organic and/or inorganic acid units containing OH groups comprises poly(meth)acrylate-based polymers.
9. The crosslinkable adhesive according to claim 1 wherein the adhesive is a pressure-sensitive adhesive.
10. A method for crosslinking crosslinkable adhesives comprising crosslinking an adhesive comprising at least one polymers functionalised with organic and/or inorganic acid units containing OH groups, wherein at least one cyclic phosphonic anhydride is used as crosslinking activator.
11. Method according to claim 10 , wherein the cyclic phosphonic anhydride is a cyclic 2,4,6-substituted 1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide.
12. A pressure sensitive adhesive obtained by a method according to claim 10 .