Polymerization of aqueous solutions of polyamide-forming reactants with adiabatic expansion thereof

Claim 1

A PROCESS FOR THE MANUFACTURE OF HIGH MOLECULAR WEIGHT POLYAMIDES BY THE CONDENSATION POLYMERIZATION OF POLYMETHYLENE DIAMMONIUM SLATS OF ALIPHATIC ALPHA, OMEGA-DICARBOXYLIC ACIDS WHICH SALTS CONTAIN FROM 8 TO 24 CARBON ATOMS, COMPRISING PUMPING A HOT AQUEOUS SOLUTION OF THE SALT CONTAINING FROM 45 TO 70% BY WEIGHT OF SAID SALT THROUGH A PRESSURE TUBE AT POLYAMIDE-FORMING TEMPERATURES UNDER A PRESSURE AT LEAST SUFFICIENT TO PREVENT THE EVOLUTION OF STEAM OF SAID POLYAMIDE-FORMING TEMPERATURE AND FOR A TIME SUCH THAT A DEGREE OF POLYMERIZATION OF FROM 1.15 TO 1.37 IS ATTAINED, SUDDENLY REDUCING THE PRESSURE TO ATMOSPHERIC PRESSURE BY PASSING THE RESULTING SOLUTION OF PREPOLYMER HAVING SAID DEGREE OF POLYMERIZATION OF FROM 1.15 TO 1.37 THROUGH A NARROW ORIFICE INTO A CHAMBER MAINTAINED AT SUBSTANTIALLY ATMOSPHERIC PRESSURE IN A MANNER SUCH THAT THE ENSUING EXPANSION IS APPROXIMATELY ADIABATIC, TO REDUCE THE PRESSURE OF SAID SOLUTION WITHOUT SOLIDIFYING IT, AND THEN HEATING SAID SOLUTION AT POLYAMIDE FORMING TEMPERATURE, IN ORDER TO COMPLETE POLYMERIZATION, AT AT LEAST ATMOSPHERIC PRESSURE, THE PRESSURE BEING BELOW THAT WHICH WILL PREVENT THE WATER OF REACTION BEING REMOVED IN THE FORM OF STEAM.