Isolation of polycarbonate with carbon dioxide

摘要

According to the invention, a special process for isolating polycarbonate from methylene chloride at temperatures of 30 DEG to 80 DEG C. in the form of a powder with residual solvent contents below 5% by weight is started up as a continuous process by starting up in a two-component nozzle, in which CO2-containing fluid and the polymer solution are continuously combined, with a large excess of CO2 and then allowing the polycarbonate/methylene chloride/CO2 fluid system to pass through the gel-forming range of the polycarbonate/methylene chloride/CO2 phase diagram with continuous reduction of the CO2 throughput to a ratio of CO2 to organic solution of 4:1 to 2:1. The process started up in this way has a particularly long useful life.