WIPED FILM REACTOR MODEL FOR NYLON 6,6 POLYMERIZATION

A wiped film model for the design and performance analysis of continuously mixed thin-film nylon 6,6 polymerizers has been developed. The description is based on composition-dependent rate and equilibrium constants, a realistic degradation scheme, and finite gas-phase condensate concentrations. Even small amounts of mixing yield very large improvements in both the mass transfer and molecular weight generation in a wiped film reactor. Nylon 6,6 degradation reactions reduce the molecular weight generation by about 15% under typical operating conditions. These wiped film reactors should be operated between 280 and 285 °C and at low pressure (≤300 mm Hg) in order to achieve maximum molecular weight and good product quality with the smallest reactor. Higher temperatures severely affect the product quality through degradation, and increasing the pressure lowers the maximum attainable molecular weight. A catalyst for the main amidation reaction could yield improved reactor performance at all but the lowest mixing rates. © 1990, American Chemical Society. All rights reserved.