Process for preparing substituted and unsubstituted diamino triazine aromatic di-isoimides
View Patent ↗The present invention deals with a novel process directed to the preparation of a novel aromatic di-isoimide chemical compound that has utility as a catalyst and as a curing agent in epoxy compositions. The di-isoimide serves effectively as a thermally activated latent catalyst in epoxy curing, thereby increasing shelf life, and avoids premature cross-linking. The process involves the reaction in a non-aqueous dipolar solvent of a dispersion PMDA and a substituted or unsubstituted diamino-triazine, preferably melamine. Reaction in the presence of rubber is also disclosed.
1. A process comprising forming a reaction mixture by combining in a solvent pyromellitic dianhydride with a substituted or unsubstituted di-amino triazine represented by the Structure II
wherein R 1 is H, halogen, hydrocarbyl, hydrocarbyloxy, hydrocarbylthio, amido, sulfonamido, cyclic amino, acyl, morpholino, piperidino, or NR′R″ where R′ and R″ are independently H, alkyl or aromatic, substituted or unsubstituted, and, maintaining said reaction mixture at a temperature in the range of −10 to +160° C., thereby producing the di-isoimide compound represented by the Structure I
2. The process of claim 1 wherein R 1 is NH 2 .
3. The process of claim 1 wherein the solvent is characterized by a dipole moment in the range of 1.5 to 3.5 Debye.
4. The process of claim 1 wherein the solvent is cyclohexanone.
5. The process of claim 1 wherein the temperature is in the range of room temperature to 50° C.
6. The process of claim 1 further comprising stirring said reaction mixture to maintain a uniform appearance thereof throughout the duration of the reaction.