MIXED COMPATIBLE ZIEGLER-NATTA/CHROMIUM CATALYSTS FOR IMPROVED POLYMER PRODUCTS Russian patent published in 2018 - IPC C08F4/24 C08F4/646 C08F4/69 C08F210/16 

FIELD: chemistry.

SUBSTANCE: disclosed are catalyst system for polymerizing olefin-based polymers and interpolymers that have a monomodal molecular weight distribution, method for the obtaining of monomodal olefin-based polymers, and an olefin-based polymer or interpolymer obtained by the process. Catalyst system comprises a Ziegler-Natta catalyst, a chromium catalyst supported on silica, and a cocatalyst comprising alkyl aluminium, wherein the molar ratio of aluminium to titanium is less than 35:1, and the molar ratio of alkyl aluminium to chromium is less than 300:1. Ziegler-Natta catalyst comprises Mg and Ti, wherein the Ziegler-Natta catalyst is obtained by either: a) combining one or more supports with one or more magnesium-containing compounds under reaction conditions to produce a first reacted product; b) reacting the first reacted product with compounds selected from the group consisting of alkyl aluminium chlorides, halogen-substituted silanes and a combination of the foregoing, to obtain a second reacted product and c) combining the second reacted product with one or more titanium-containing compounds selected from the group consisting of titanium alkoxides, titanium halides, titanium amides and combinations thereof, under reaction conditions to obtain a Ziegler-Natta catalyst; or by spray drying a solution comprising one or more of the elements Si, Mg, Ti, Hf and Zr in an alcoholic solvent, followed by halogenation of Mg, Ti, Hf and Zr. Chromium catalyst supported on silica includes at least one of the listed components: a) a supported reduced silyl chromate catalyst and b) a supported reduced chromium oxide catalyst that has been reduced with diethylaluminium ethoxide (DEALE). Ziegler-Natta catalysts in catalytic systems work extremely well without the addition of excess amounts of cocatalyst, which makes it possible to use supported chromium-based catalysts, the action of which would otherwise be suppressed by the presence of alkyl aluminium.

EFFECT: it has been found that the inclusion of chromium catalysts in Ziegler-Natta catalysts or their combined supply provides the molecular architecture of the final polyolefins, for example polyethylenes, which can provide a polymer with a monomodal molecular weight distribution.

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