Process for continuous recovery of solid polycarbonate from solutions thereof in organic solvents

Claim 1

A continuous process for the recovery of polycarbonates from solutions thereof in organic solvents, said process consisting of the following phases: (a) feeding of the polycarbonate solution at a temperature comprised between 0° and 120° C., through one or more feeding ducts into the narrow zone or the diverging stretch of a DeLaval-type nozzle run through by water vapor at respectively sonic or ultrasonic speed, maintaining feeding ratios vapor/polycarbonate solution comprised between 1 and 5 kg of vapor per kg of solution, with formation of a dispersion of particles of polycarbonate in the vapor; (b) continuous feeding of the dispersion resulting from phase (a) to a pipe-in-pipe heat exchanger, directly connected to the diverging stretch of the nozzle, said heat exchanger having a mean thermal exchange coefficient comprised between 500 and 1500 Kcal/hr.sq.mt°C., and a cross-section growing along its development, and in which exchanger the dispersion, maintained at 100°-140° C. for dwell times comprised between 0.05 and 5 seconds, has a flow rate of at least 90 mt/sec. in the initial stretch and from 10 to 50 mt/sec. in its final stretch; thereby obtaining solid minute polycarbonate particles dispersed in the vapor phase consisting of the vapors of the solvent and of water vapor, and separating the solid polycarbonate particles from the vapors.