A process for the production of a polymer containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid (PA-410) having a viscosity number (VN) of at least 105 ml/gram includes making a solution of a salt of butane-1,4-diamine and 1,10-decanedioic acid in water, concentrating the solution of the salt at a temperature of between 100 and 180° C. and a pressure of between 1.0 and 3.0 bar to a water content of between 4 and 8 wt %, producing a prepolymer from the salt containing monomer units of butane-1,4-diamine and 1,10-decanedioic acid at a temperature of between 185 and 205° C., and thereafter subjecting the prepolymer to post condensation.