Patent ID: 8822631

Claim:
A process for the production of a polymer containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid (PA-410) comprising the steps of: 1) making an aqueous salt solution comprising a salt of butane-1,4-diamine and 1,10-decanedioic acid in water, 2) concentrating the aqueous salt solution at a temperature of between 100 and 180° C. and at a pressure of between 0.8 and 6.0 bar to achieve a water content of the aqueous salt solution of between 2 and 8 wt %, 3) producing from the salt a prepolymer containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid at a temperature of between 185 and 205° C., and thereafter 4) subjecting the prepolymer to post-condensation to obtain a PA410 polymer having a viscosity number (VN) of at least 100 ml/gram as measured according to ISO 307, version 2007, in 90 wt. % formic acid at 25° C.