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AssigneeTicona LLC
InventorsMichael Haubs, Eberhard Mann, Jurgen Lingnau
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A process and an apparatus for the preparation of oxymethylene polymers is described. The process encompasses the polymerization of a monomer that forms oxymethylene groups, if appropriate in the presence of a cyclic acetal, together with an acetal of formaldehyde and with an initiator for cationic polymerization, preferably in a gas-tight kneader or extruder. The temperature profile of the polymerization here is designed in such a way that the polymerization mixture, which is initially heterogeneous by virtue of precipitating polymer, is converted to a homogeneous phase at the end of the polymerization. The homogeneous phase in which the polymer is present in liquid form is stabilized via addition of deactivators. After removal of volatile constituents, oxymethylene polymers are obtained with high thermal stability and with good mechanical properties. The oxymethylene polymers can be prepared at low energy cost and their properties can be adjusted as desired via prescription of the temperature profile during the polymerization.
A process for the preparation of oxymethylene polymers via polymerization of at least one monomer that forms —CH2—O— units, if appropriate in combination with at least one comonomer copolymerizable therewith having at least one C—C bond, and also in the presence of a chain transfer agent and of an initiator for cationic polymerization, which comprises carrying out the polymerization in a first phase in a heterogeneous polymerization mixture and, following this, in a second phase in a homogeneous polymerization mixture.
The process as claimed in 1, wherein the polymerization mixture, still active at the end of the polymerization, is terminated in the second step via addition of one or more deactivators.
Dependencies are inferred from the claim text.