Continuous preparation of nylon with diamine recycling

US4537949A · kind A · utility

Assignee

• BASF SE

Inventors

• Franz Schmidt · Mannheim, DE
• Gunter Pipper · Bad Dürkheim, DE
• Josef G. Floss · Neustadt, DE
• Franz Zahradnik · Ludwigshafen, DE

Key dates

• Filing date: Jun 14, 1984
• Grant date: Aug 27, 1985
• Expiry date: Jun 14, 2004

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29B7/86
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Nylons are prepared by a continuous process in which, in an evaporator zone, an aqueous solution of a salt of a dicarboxylic acid of 6 to 18 carbon atoms and a diamine of 6 to 18 carbon atoms is heated to 250.degree.-300.degree. C. under superatmospheric pressure, with simultaneous vaporization of water and formation of a prepolymer, the prepolymer and the vapors are separated continuously, the vapors are rectified and the entrained diamines are recycled, and the prepolymer is fed to a polycondensation zone and subjected to polycondensation under superatmospheric pressure of from 1 to 10 bar and at from 250.degree. to 300.degree. C., wherein the aqueous salt solution is heated under superatmospheric pressure of from 1 to 10 bar during a residence time of less than 60 seconds, with the proviso that, on leaving the evaporator zone, the degree of conversion is not less than 93% and the water content of the prepolymer is not more than 7% by weight.