Continuous hydrolytic preparation of polylactams
AssigneeBASF SE
InventorsGunter Pipper, Rainer Theysohn, Franz Zahradnik
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Abstract
Polylactams are prepared continuously by a process in which a lactam containing from 1 to 25% by weight of water is heated in a prepolymerization zone under a pressure of from 1 to 10 bar at from 220.degree. to 280.degree. C. for 1 to 10 minutes, water being vaporized at the same time, with the proviso that the degree of conversion on emergence from the prepolymerization zone is not less than 85%, the prepolymer and the vapor are separated continuously, and the prepolymer is passed into a polymerization zone and is polymerized further under superatmospheric pressure at from 240.degree. to 290.degree. C.
Claims7
A process for the continuous preparation of a molten or solid polylactam, which comprises
- (a) feeding a lactam melt containing from 1 to 25% by weight of water into a prepolymerization zone,
- (b) heating this lactam melt in the prepolymerization zone at from 220.degree. to 280.degree. C. under a pressure of from 1 to 10 bar for from 1 to 10 minutes, formation of a prepolymer melt and vaporization of the water taking place at the same time, and removing the melt from the prepolymerization zone, with the proviso that, when the melt emerges from the prepolymerization zone, the degree of conversion is not less than 85%,
- (c) continuously separating off steam from the resulting melt of the prepolymer,
- (d) transferring the prepolymer melt to a polymerization zone and
- (e) polymerizing the prepolymer melt in the polymerization zone under superatmospheric pressure and at from 240.degree. to 290.degree. C.
Dependencies are inferred from the claim text.