Solvay & Cie (societe Anonyme)

Solvay Polyolefins Europe-belgium

Jean-marie Blondin

Qui Long Nguyen

Jean-paul Burnay

Nicole Dewaele

Pierre Malfroid

Olivier Lhost

Qui L Nguyen

Jean-Marie Blondin

Jean-Paul Burnay

Joel Kaisin

Martine Frederickx

The invention relates to a process for the production of ethylene polymers by the polymerization of ethylene or the copolymerization of ethylene with one or more C to C olefins in contact with a chromium-based catalyst deposited on a support essentially consisting of silica. According to the invention, the chromium catalyst is subjected in succession to a heat treatment in nitrogen and then to a heat treatment in air under defined temperature conditions before bringing it into contact with ethylene and, optionally, one or more olefins under polymerizing conditions. The process of the invention makes it possible to manufacture ethylene polymers having an improved compromise between processability, stiffness and resistance to slow crack growth.

Process for production of ethylene polymers

In a first stage, a lactone is polymerized by an ionic route in vinyl chloride with the aid of a catalyst consisting of the product, optionally complexed with tetrahydrofuran, of the reaction of an alkylmetal with ethylenically unsaturated alcohol, optionally in the presence of water and, in a second stage, the said vinyl chloride is polymerized by a radical route in an aqueous suspension and in the presence of the polymerization medium originating from the first stage, to which other unsaturated monomers are optionally added. The invention also relates to new modified vinyl chloride polymers consisting of lactone polymers whose number-average molecular weight is less than 5,000, grafted with vinyl chloride polymers.

Process for the manufacture of vinyl chloride polymers modified with

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Brussels, Belgium

Nicole Dewaele