Continuous preparation of nylon from aqueous salt solution in precondensation zone having baffles

A process for the preparation of a nylon, which comprises

• (a) passing 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 through a tubular precondensation zone possessing baffles,
• (b) heating the aqueous solution in the first third of the precondensation zone to 250.degree.-300.degree. C. under superatmospheric pressure of from 1 to 10 bar, with the formation of a vapor phase containing steam and diamines and not less than 93% conversion of the salt to form a prepolymer,
• (c) bringing the vapor phase into intimate contact with the prepolymer in the remaining two thirds of the precondensation zone,
• (d) separating off the prepolymer from the vapor phase,
• (e) transferring the prepolymer to a condensation zone,
• (f) condensing the prepolymer in the condensation zone under superatmospheric pressure of from 1 to 10 bar and at from 250.degree. to 300.degree. C.,
• (g) rectifying the vapor obtained in stage (d) in a column under the pressure used for the precondensation, thus separating the vapor into steam and diamine, and
• (h) discharging the nylon obtained in stage (f) through a discharge zone with removal of water, cooling and comminuting the nylon, and condensing the nylon in the solid phase, with the steam separated off in stage (g), until the desired viscosity is obtained.