Molecular weight controllers combination for caprolactam polymerization processes

摘要

The invention is concerned with a combination of molecular weight controllers to be used in the production of a stabilized polyamide having a low content of monomers and oligomers and a high dye-taking capability by polymerization of caprolactam. The combination comprises: (a) a primary monofunctional amine having its boiling point at 180 DEG C. above, and a basic dissociation constant Kb>/=1.7x10-5; (b) a monofunctional organic acid having a Ka>1.5x10-5; and (c) an aminoacid containing at least ten carbon atoms having the -NH2 group salified by a monofunctional organic or inorganic acid which has Ka>1.0x10-2. With this combination, a polyamide is obtained which, following residence in the molten state, has a monomer content of 0.25% or less and a dimer content of 0.15% or less.