Polyurethanes made with copper catalysts
Polyisocyanate-based polymers are formed by curing a reaction mixture containing at least one polyisocyanate and at least one isocyanate-reactive compound having at least two isocyanate-reactive groups in the presence of a copper catalyst that contains at least one copper atom associated with a polydentate ligand that contains at least one nitrogen-containing complexing site.
1. A process for preparing a polyisocyanate-based polymer, comprising forming a reaction mixture containing at least one polyisocyanate, at least one isocyanate-reactive compound having at least two isocyanate-reactive groups and at least one copper catalyst, and then curing the reaction mixture to form a polymer, wherein the copper catalyst contains at least one copper atom associated with a polydentate organic ligand that contains at least two complexing sites, of which at least one is nitrogen-containing, wherein the ligand is
an α-amino hydroxyl compound or α-imino hydroxyl compound having either of the structures I and IA
wherein R 5 is a group that is bonded to the indicated nitrogen atom through a carbon, oxygen, nitrogen or silicon atom, each R 1 is a linear or branched alkyl group that has up to thirty carbon atoms which may be substituted with an inert substituent, or an aromatic group which may be substituted with alkyl, hydrocarbyl, one or more complexing sites and/or one or more inert substituents, each R 3 is selected from hydrogen; a linear or branched alkyl group that has up to thirty carbon atoms which may be substituted with one or more complexing sites or one or more inert substituents; a cycloalkyl group which may be substituted with one or more hydrocarbyl substituents, inert substituents and/or complexing sites; and an aromatic group which may be substituted with alkyl or other hydrocarbyl substituents, one or more inert substituents and/or one or more complexing sites, and each R 4 is independently hydrogen or a group that is bonded to the indicated nitrogen atom through a carbon, oxygen, nitrogen or silicon atom, further provided that in structure I an R 4 group and an R 5 group may together form a divalent group that is bonded to the indicated nitrogen atom through carbon, oxygen, nitrogen and/or silicon atoms, and further provided that an R 3 and an R 5 group may together form a divalent group that is bonded to the indicated carbon atom and the indicated nitrogen atom though carbon, oxygen, nitrogen and/or silicon atoms.
2. The process of claim 1 wherein the polyisocyanate-based polymer is a polyurethane, polyurea, or polyurethane-urea.
3. The process of claim 1 , wherein the reaction mixture further contains a blowing agent and a surfactant, and the polyisocyanate-based polymer is a foam.
4. The process of claim 1 , wherein the isocyanate-reactive compound includes a polyol having a molecular weight of from 800 to 12,000 and an average of from 1.8 to 2.5 hydroxyl groups per molecule, and the polyisocyanate-based polymer is a cast elastomer.
5. The process of claim 1 wherein the reaction mixture contains at least one additional catalyst.