Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1999-12-13
2000-09-26
Lambkin, Deborah C.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
528417, 549472, C08J 900, C08G 5900, C07D30702
Patent
active
06124368&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an improved process for the preparation of polytetrahydrofuran, polytetrahydrofuran copolymers, diesters or monoesters of these polymers by the polymerization of tetrahydrofuran in the presence of at least one telogen and/or comonomer over a heterogeneous supported catalyst containing at least one metal sulfate, metal hydrogensulfate or metal oxysulfate.
Polytetrahydrofuran ("PTHF"), also known as poly(oxybutylene glycol), is a broadly used intermediate in the plastics and synthetic fiber industry and serves inter alia for the preparation of polyurethane, polyester and polyamide elastomers. In addition, it is, as are also some of its derivatives, a valuable auxiliary for many applications, such as dispersing agents or for the process of decolorizing ("de-inking") waste paper.
PTHF is advantageously prepared on an industrial scale by polymerization of tetrahydrofuran over catalysts in the presence of reagents, the addition of which makes it possible to control the chain length of the polymer chains and thus to set the average molecular weight to the desired value (chain-terminating agents or "telogens"). The control takes place in this case by varying the type and amount of the telogen. By selecting suitable telogens functional groups can be additionally introduced at one or both ends of the polymer chain. Thus for example by using carboxylic acids or carboxylic anhydrides as telogens the monoesters or diesters of PTHF can be prepared.
Other telogens are effective not only as chain-terminating agents, but are also incorporated in the growing polymer chain of the PTHF, that is to say they not only operate as a telogen, but also as a comonomer and can therefore be equally well designated as a telogen or as a comonomer. Examples of such comonomers are water or telogens containing two hydroxy groups such as the di-alcohols. Examples of such di-alcohols are ethylene glycol, butylene glycol, butane-1,4-diol, hexane-1,6-diol or low molecular weight PTHF Other suitable comonomers are 1,2-alkylene oxides such as ethylene oxide or propylene oxide, 2-methyltetrahydrofuran or 3-methyltetrahydrofuran. The use of such comonomers, except water, butane-1,4-diol and low-molecular THF, leads to the preparation of tetrahydrofuran copolymers. In this manner it is possible to chemically modify the PTHF. One example thereof is the use of the telogen 2-butyne-1,4-diol, the addition of which causes a proportion of C.tbd.C triple bonds to be present in the polymer chains of the PTHF.
Such modified PTHF can, due to the reactivity of these triple bonds, be further refined chemically at these sites, for example by hydrogenation of the triple bonds to double bonds, by subsequent addition polymerization of different monomers ("grafting") for varying the properties of the polymer, cross linkage for the formation of polymers having a comparatively rigid structure, or other measures commonly used in polymer chemistry. Total hydrogenation of the triple bonds that are present is likewise possible and generally leads to PTHF having a particularly low color index.
DE-A 44 33 606 describes a process for the preparation of PTHF, PTHF diesters of C.sub.2 -C.sub.20 monocarboxylic acids or PTHF monoesters of C.sub.1 -C.sub.10 monocarboxylic acids by the polymerization of tetrahydrofuran over a heterogeneous catalyst in the presence of one of the telogens water, butane-1,4-diol, PTHF having a molecular weight of 200 to 700 dalton, a C.sub.1 -C.sub.10 monocarboxylic acid or a carboxylic anhydride derived from C.sub.2 -C.sub.20 monocarboxylic acids or mixtures of these telogens, where the catalyst is an optionally sulfate-doped supported catalyst, which contains a catalytically active amount of an oxygen-containing tungsten or molybdenum compound or mixtures of these compounds on an oxidic support material and which, following application of the precursor compounds of the oxygen-containing molybdenum and/or tungsten compounds to the support material precursor, has been calcined at temperatures of 500.degree. C. to 1000
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Becker Rainer
Eller Karsten
Plitzko Klaus-Dieter
Sigwart Christoph
BASF - Aktiengesellschaft
Lambkin Deborah C.
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