Continuous solid-state polymerization process and reactor column for use therein

A continuous solid-state polymerization process for preparing a polyamide derived from diamine and dicarboxylic acid, the process comprising steps of

• feeding solid diammonium dicarboxylate salt into a reactor column comprising successive multifunctional zones comprising heating sections and gas-outlet sections, and a residence zone comprising at least one gas-inlet section;
• transporting the salt, or where applicable a polymerizing mixture or a polyamide resulting thereof, as a moving packed bed through the successive multifunctional zones, while
• heating the salt, respectively the polymerizing mixture and polyamide, in the heating sections, thereby polycondensing the salt to form a polymerizing mixture, respectively further polycondensing the polymerizing mixture to form a polyamide, and optionally further polycondensing the polyamide to form a polyamide with higher molecular weight, and producing water vapor, and
• removing the water vapor via gas-outlet sections;
• and
• further transporting the polyamide as a moving packed bed through the residence zone, while
• introducing a gaseous diamine into the residence zone via a first gas-inlet section inside the residence zone;
• and optionally introducing an inert gas into the reactor via a second gas-inlet section below the first gas-inlet section;
• discharging the resulting polyamide from the reactor column;
• wherein the salt, the polymerizing mixture and polyamide are kept in the solid-state and wherein the heating sections comprise static heat exchangers.