Catalysts of the oxirane-anhydride reaction

A method of curing an epoxy resin system comprising reacting at least one epoxy compound containing at least one oxirane ring with at least one organic polybasic acid anhydride in the presence of an effective catalytic amount of a synergistic catalyst mixture of at least one active trivalent chromium III carboxylate which is emerald green in color and is absent absorption at 2750 millimicrons and a cocatalyst containing substituents selected from the group consisting of alkyl, aryl, aralkyl and alkaryl, said cocatalyst being selected from tri- and tetra-substituted compounds of the group consisting of quaternary-substituted ammonium halides, quaternary -substituted ammonium hydroxides;

• quaternary-substituted phosphonium halides;
• tri-substituted arsines;
• tri-substituted amine oxides;
• tri-substituted phosphine oxides;
• tertiary-substituted phosphines;
• tertiary-substituted amines;
• and mixtures thereof, each alone or in combination with a reactive promoter selected from the group consisting of phenols and low molecular weight mono carboxylic acids and alcohols, and compounds containing two or more of the co-catalytic functional groups from the cocatalysts set forth above, in the same molecule, alone or in combination with any of the reactive promoters, said chromium III carboxylate and cocatalyst each being present in the reaction mixture at a level of at least 0.015 weight percent.

The method of polymerizing epoxy compounds with carboxylic acid anhydrides which comprises carrying out the polymerization in the presence of a catalyst mixture comprising at least one chromium III carboxylate which is emerald green in color and is absent absorption at 2750 millimicrons and a cocatalyst containing substitutents selected from the group consisting of alkyl, aryl, aralkyl and alkaryl, said cocatalyst being selected from tri- and tetra-substituted compounds of the group consisting of quaternary-substituted halides;

• quaternary-substituted ammonium hydroxides;
• quaternary-substituted phosphonium halides;
• tri-substituted arsines;
• tri-substituted amine oxides;
• tri-substituted phosphine oxides;
• tertiary-substituted phosphines;
• tertiary-substituted amines;
• and mixtures thereof, each alone or in combination with a phenol;
• each alone or in combination with one or more reactive accelerators selected from the group consisting of carboxylic acids and alcohols;
• and compounds containing two or more of the co-catalytic functional groups from the cocatalysts set forth above, in the same molecule, alone or in combination with any and all of (1) any of the cocatlysts, (2) phenols, and (3) reactive accelerators, said chromium III carboxylate and cocatalyst each being present in the reaction mixture at a level of at least 0.015 weight percent.