| abstract |
A process for the continuous production of endgroup-stable homo- and copolyoxymethylenes in a homogeneous phase, in which cyclic formaldehyde oligomers are polymerized in a tube reactor with static mixing elements in the presence of protonic acids as initiators in amounts of 0.005 to 500 ppm in a polymerization zone, the residence time of the reaction components in this Zone is 0.1 to 10 min and the polymerization is immediately followed by deactivation of the initiator, there being a smooth transition between the polymerization and deactivator zone, which is determined only by the addition of the deactivator, and in addition to the deactivation, stabilization of the chain ends is carried out in the presence of residual monomers, whereupon the volatile constituents are removed from the reaction mixture in a downstream degassing unit. The stabilization is carried out in the presence of alkaline substances, either at temperatures from 150 ° C. to 250 ° C., optionally in the presence of water or primary alcohols, or at 175 ° C. to 250 ° C. in the absence of these additives. |