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    3.
    发明专利
    未知

    公开(公告)号：DE4327246A1

    公开(公告)日：1995-02-16

    申请号：DE4327246

    申请日：1993-08-13

    Applicant: HOECHST AG

    Inventor： HOFFMOCKEL MICHAEL ,  MUECK KARL-FRIEDRICH ,  SCHLAF HELMUT

    IPC: C08G2/00 ,  B01J19/24 ,  C08G2/10 ,  C08G2/30 ,  B29B7/76 ,  B29B7/84

    Abstract: The invention relates to an apparatus for continuous preparation of polyacetals in homogeneous phase in the form of a flow tube equipped with static mixer elements, in which the static mixer elements a) are arranged one after the other, b) vary in length and diameter in accordance with the individual process step and c) are not separated by built-in damming elements or constrictions.

    4.
    发明专利
    未知

    公开(公告)号：BR9503924A

    公开(公告)日：1996-09-17

    申请号：BR9503924

    申请日：1995-09-04

    Applicant: HOECHST AG

    Inventor： FLEISCHER DIETRICH ,  HOFFMOCKEL MICHAEL ,  MUECK KARL-FRIEDRICH ,  SEXTRO GUENTER

    IPC: C08G2/10 ,  C08G2/00 ,  C08G2/18 ,  C08G2/24 ,  C08G2/28 ,  C08G2/36

    Abstract: Prodn. of acetal copolymers with simultaneous end gp. stabilisation is effected in homogeneous phase by copolymerising cyclic formaldehyde oligomers with cyclic acetal cpds. in a polymerisation reactor with addn. of a basic substance to deactivate the initiator following the copolymerisation, the process being such that the prod. (with its non-stable chain end content in presence of residual monomers reduced to 0.01-1%) is passed to a granulator where the bulk of the residual monomer is lost and the remaining residual monomers and dissolved impurities are removed by solvent extn. prior to drying and stabilising the prod. and then granulating it.

    PROCESS FOR THE PREPARATION OF POLYACETALS
    5.
    发明专利
    PROCESS FOR THE PREPARATION OF POLYACETALS 未知

    公开(公告)号：CA2130030A1

    公开(公告)日：1995-02-14

    申请号：CA2130030

    申请日：1994-08-12

    Applicant: HOECHST AG

    Inventor： HOFFMOCKEL MICHAEL ,  MUECK KARL-FRIEDRICH ,  SCHLAF HELMUT ,  BURG KARLHEINZ

    IPC: B01J19/24 ,  C08G2/00 ,  C08G2/10 ,  C08G2/30 ,  C08L59/00

    Abstract: Process for the preparation of polyacetals Process for continuous preparation of homo- and copolyoxymethylenes with stable end groups in a homogeneous phase, in which in a tubular reactor with static mixing elements cyclic formaldehyde oligomers are polymerized in the presence of protonic acids as initiators in amounts of 0.005 to 500 ppm in a polymerization zone, in which the residence time of the reaction components in this zone is 0.1 to 10 min and in which the initiator is deactivated immediately after polymerization, there being a fluid transition between the polymerization and deactivator zones which is determined solely by the addition of deactivator, and in which, besides deactivation, stabilization of the chain ends is carried out in the presence of residual monomers, with the volatile constituents being removed from the reaction mixture in a subsequent vent unit. Stabilization is carried out in the presence of alkaline substances, either at temperatures of 150.degree.C to 250.degree.C, if necessary in the presence of water or primary alcohols, or at 175.degree.C to 250.degree.C in the absence of these additives.

    7.
    发明专利
    未知

    公开(公告)号：BR9403237A

    公开(公告)日：1995-04-11

    申请号：BR9403237

    申请日：1994-08-12

    Applicant: HOECHST AG

    Inventor： HOFFMOCKEL MICHAEL ,  MUECK KARL-FRIEDRICH ,  SCHLAF HELMUT ,  BURG KARLHEINZ

    IPC: B01J19/24 ,  C08G2/00 ,  C08G2/10 ,  C08G2/30 ,  C08G2/08

    Abstract: Process for the continuous preparation of homo- and copolyoxymethylenes with stable terminal groups in the homogeneous phase, in which cyclic formaldehyde oligomers are polymerised in the presence of protic acids as initiators in amounts of from 0.005 to 500 ppm in a polymerisation zone in a tubular reactor with static mixing elements, where the residence time of reaction components in this zone is from 0.1 to 10 minutes, and the polymerisation is followed directly by deactivation of the initiator, where there is a gradual transition from the polymerisation zone to the deactivator zone which is defined merely by the addition of the deactivator, and where, in addition to the deactivation, stabilisation of the chain ends is carried out in the presence of residual monomers, after which, in a subsequent degassing unit, the volatile constituents are removed from the reaction mixture. The stabilisation is carried out in the presence of alkaline substances, either at temperatures of from 150 DEG C to 250 DEG C, optionally in the presence of water or primary alcohols or at from 175 DEG C to 250 DEG C in the absence of these additives.

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