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AssigneeHoechst Aktiengesellschaft
InventorsDietrich Fleischer, Michael Hoffmockel, Karl-Friedrich Muck, Gunter Sextro
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In the process for the preparation, with simultaneous end group stabilization, of polyacetal copolymers in a homogeneous phase and working up thereof, cyclic formaldehyde oligomers are copolymerized with cyclic acetals in the presence of an initiator in a polymerization reactor and immediately thereafter the initiator is deactivated by addition of basic substances, the unstable chain ends being degraded down to 0.01% to 1% in the presence of residual monomer, the product losing the majority of the residual monomer at the reactor outlet by letting down into a pelletizing device and the residual monomer which remains and the impurities dissolved in the product being removed by extraction with solvents and the product being pelletized, after drying and stabilization.
In a process for the preparation and simultaneous end group stabilization of a polyacetal copolymer in a homogeneous phase, in which a cyclic formaldehyde oligomer is copolymerized with a cyclic acetal in the presence of an initiator in a polymerization reactor and immediately thereafter the initiator is deactivated by addition of a basic substance, which comprises a procedure in which the unstable chain ends are degraded down to 0.01% to 1% in the presence of residual monomer, the improvement according to which the product spontaneously solidifies due to evaporation of the residual monomer at the reactor outlet by letting down into a pelletizing device and the residual monomer which remains and the impurities dissolved in the product are removed by extraction with a solvent and the product is pelletized, after drying and stabilization.
Dependencies are inferred from the claim text.