Process for the preparation of thermally crosslinkable polymer melts by concentration of polymer solutions and their simultaneous mixing with modifying liquids in a planetary roller extruder

摘要

Process for the preparation of thermally crosslinkable polymer melts by concentration of polymer solutions and their simultaneous mixing with modifying liquids in a planetary roller extruder, characterized in that a) the planetary roller extruder consists of an atmospherically operated filling zone of at least one roll cylinder and a downstream, operated under vacuum degassing and cooling zone, the length of the atmospherically operated filling zone not more than half, preferably not more than one third of the total length of Planetary roller extruder is, b) the operated under vacuum degassing and cooling zone of the planetary roller extruder consists of at least four, preferably exactly four coupled roll cylinders, each having a vacuum opening in the jacket whose cross section makes up at least 5% of the planetary spindles overmolded shell surface and created by the vacuum become, c) all roll cylinders are separated by intermediate rings, whose free cross sections are selected so that the polymer to be processed can accumulate there and thus gas-tightly separates all the roll cylinders, d) each of the at least four roll cylinders in the degassing and cooling zone forms an independently operable vacuum zone, the ratio of the pressure in the first vacuum zone of the first roll cylinder to the pressure in the second vacuum zone of the second roll cylinder and the ratio of the pressure in the second roll Vacuum zone of the second roll cylinder to the pressure in the third vacuum zone of the third roll cylinder is at least 3: 1, preferably at least 5: 1, e) the pressure in the third vacuum zone of the third roller cylinder is less than 15 mbar, preferably less than 10 mbar and particularly preferably less than 5 mbar, f) the pressure in the fourth vacuum zone of the fourth roll cylinder is preferably between exactly or more than 100 mbar and 500 mbar, g) the polymers are fed to the planetary roller extruder in the form of a polymer solution consisting of polymers dissolved in solvent, wherein the polymer solution is brought before entry into the planetary roller extruder under overpressure of up to 10 bar to a temperature which is at least 60 ° C, preferably at least 80 ° C and more preferably at least 100 ° C above the temperature at which the same polymer solution boils at atmospheric pressure, h) the polymer solution is fed via a pressure-holding valve as superheated liquid directly into the first roll cylinder of the atmospherically operated filling zone, i) after evaporation of at least parts of the solvent in the atmospherically operated filling zone, the mass flow of polymer solution fed into the first vacuum zone of the first roll cylinder is less than 75%, preferably less than 65%, more preferably less than 55% of the mass flow originally supplied to the planetary roller extruder Polymer solution is, j) the flow temperatures of the central spindle and the vacuum-standing roll cylinders in the degassing and cooling zone are set so that the polymers to be degassed remain in the plasticized state, k) the polymer solution in the region of the fourth vacuum zone of the fourth roll cylinder, liquid thermal crosslinkers and optionally crosslinking accelerators, dye solutions or dye dispersions are preferably metered in continuously, wherein the metering for these substances are within the first third of the process length of this fourth vacuum zone, l) each roll cylinder in the degassing and cooling zone has one, in particular at least two separate circles for liquid temperature control, wherein the polymer solution is cooled so that there is no induced by the thermal crosslinking gelling of the polymer solution within the planetary roller extruder or optionally downstream downstream aggregates comes, m) the residual content of solvent in the polymer solution after the third vacuum zone is less than 1% by weight, preferably less than 0.5% by weight and particularly preferably less than 0.1% by weight, n) the polymer solution coming from the last roll cylinder is fed to a coating unit, more preferably inline.