Basf Aktiengesellschaft

Siegfried Weber

Guido Funk

Roland Saive

Rainer Konrad

Hans-Joachim Mueller

Kaspar Evertz

Rainer Hemmerich

Dieter Lilge

Guenther Schweier

Juergen Kerth

Peter Koelle

Low-shrinkage polyethylene moulding compounds

A novel Phillips catalyst for the copolymerization of ethylene with .alpha.-olefins, contains, as a catalytically active component, a finely divided, aluminum silicate-supported, phosphorus-containing chromium catalyst. This can be prepared by applying at least one organic phosphorus(III), (IV) and/or (V) compound and at least one chromium(III) compound which does not react with said phosphorus compounds under the reaction conditions used, in succcession in any order or simultaneously, to a finely divided aluminum silicate hydrogel or xerogel with formation of a catalyst intermediate and activating the catalyst intermediate at elevated temperatures in an oxidizing atmosphere, with the result that the chromium catalyst is formed. The novel Phillips catalyst gives ethylene/.alpha.-olefin copolymers in which the comonomers are more uniformly distributed over the copolymer chains than is the case with ethylene/.alpha.-olefin copolymers which have been prepared with the aid of conventional Phillips catalysts. Moldings which have been produced from the ethylene/.alpha.-olefin copolymers obtained in the novel procedure have a particularly high environmental stress cracking resistance and an excellent creep rupture strength.

Phillips catalyst and its use for the preparation of

A novel Phillips catalyst for the homopolymerization of ethylene and the copolymerization of ethylene with .alpha.-olefins contains as catalytically active components a specific chromium catalyst on an aluminum phosphate support and cocatalysts of the formula I to IV, ##STR1## where M is lithium, sodium and potassium,

Phillips catalyst and its use for preparing ethylene homopolymers and

A supported catalyst for ethene polymerization by Phillips catalysis is disclosed. The supported catalyst is prepared by (1) mixing a porous silicate in an inert, organic liquid to produce a silicate suspension, (2) providing an ester of phosphoric acid or phosphorous acid, (3) mixing an organic liquid, a chromium compound, and a trialkylaluminum compound to produce a chromium compound/aluminum compound and combining the silicate suspension, the phosphorus compound and the chromium compound/aluminum compound suspension. This resulting suspension is evaporated to dryness to form a catalyst intermediate. The catalyst intermediate is heated in nitrogen, then heated in an oxygen-containing atmosphere, and then heated again in nitrogen to produce an activated catalyst. The activated catalyst is suspended in an organic liquid and treated with an alkyl boron compound to produce the desired supported catalyst.

Supported chromium oxide catalyst

Ultrahigh molecular weight ethylene polymers are prepared in the gas phase in a thoroughly mixed bed of finely divided polymer by continuous introduction of the monomer into a polymerization system at 60.degree.-120.degree. C. and 5-60 bar in the presence of a reaction product of a titanium-containing catalyst and an antistat and in the presence of a monohydric or polyhydric alcohol.

Avoidance of colored impurities in the preparation of ultrahigh

Ultrahigh molecular weight ethylene polymers are prepared in the gas phase in a thoroughly mixed bed of finely divided polymer by continuous introduction of the monomer into a polymerization system at 60.degree.-120.degree. C. and 5-60 bar in the presence of a reaction product of a titanium-containing catalyst and an antistat.

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Weinheim, Germany

Siegfried Weber