Process for the preparation of multifunctional polycarbodiimides which are used as crosslinking agents

摘要

A process for the preparation of multifunctional polycarbodiimides, which are used as crosslinking agents, in which the polycarbodiimide is prepared by reacting mono- and polyisocyanates in the presence of a mono- or polyisocyanate that contains one or multiple additional reactive functional groups and in the presence of a carbodiimide catalyst, and thereafter terminating or chain extending the polycarbodiimide chain. Between 0 and 10% of an organic solvent and/or between 0 and 30% of a plasticizer and/or between 0 and 30% of a surface active component is added to the product during, before or after the polycarbodiimide forming reaction and/or the capping reaction and/or the chain extending reaction. Further, the invention relates to a coating mixture in which the polycarbodiimide is used as crosslinking agent and to the cured material obtained with the coating mixture.

主权项

1. A process for the preparation of water-dispersible multifunctional polycarbodiimides to be used as crosslinking agents, comprising:
A. the reaction of a mono- and/or polyisocyanate at 80-180° C. in the presence of a carbodiimide catalyst, in which a polycarbodiimide or an isocyanate functional polycarbodiimide is formed with a mean value of 1-10 carbodiimide functions; B. terminating and/or chain extending the isocyanate functional polycarbodiimide chain, during or after the formation of the polycarbodiimide chain by the addition of 0.05 to 1.0 equivalent, regarding to the isocyanate functions that are not consumed in the formation of the polycarbodiimide chain, of a compound containing a hydrophilic group and one or multiple amine and/or hydroxyl functions, together with, prior to, or followed by capping of the remaining isocyanate functions with a compound containing one or multiple amine and/or hydroxyl functions, in which the compound containing one or multiple amine and/or hydroxyl functions can also contain an additional functional group,where in step A one or multiple mono- and/or polyisocyanates containing one or multiple additional functional groups, of which the isocyanate group contributes to the carbodiimide formation is present, at least one of said additional functional groups being selected from the group consisting of: halogen; alkenyl; arylalkene; alkynyl; arylalkyn; alkadiene; aldehyde; dialkylacetal; dithioacetal; ketone; unsaturated aldehyde; ketone; ketone ester; carboxylic ester; nitrile; imine; alkylalkoxy silane; alkoxysilane; anhydride; mixed anhydride; oxime-protected diisocyanate; diketone; ketoester; thioketoester; ketothioester; and thioketothioester.