| 摘要 |
<p>A process for preparing polyoxymethylene homopolymers or copolymers by homopolymerization or copolymerization of trioxane or additionally of suitable comonomers, in which trioxane which still comprises residual monomers is firstly prepared in a monomer plant and is degassed in one or more stages to give one or more vapor streams ( 13, 14 ) which are, if appropriate, fed to a condenser (K) in which the condensable fractions of these vapor streams are condensed to give a condensate ( 15 ) which is recycled to the polymerization reactor (P) and one or more gaseous, formaldehyde-comprising streams ( 16 ) and also a partially degassed polyoxymethylene homopolymer or copolymer ( 17 ) which is fed to an extruder (E) or kneader and is mixed with customary additives and processing aids in this to give a polymer melt ( 19 ) and extraction of a formaldehyde-comprising extruder or kneader offgas ( 18 ) from the extruder (E) or kneader, wherein the formaldehyde-comprising secondary streams ( 14, 16, 18 ) from the polymer plant are recycled directly without addition of auxiliaries to the monomer plant, is proposed</p> |
