Borealis Polymers Oy

Borealis Technology Oy

Neste Oy

Aimo Sahila

Ali Harlin

Hilkka R Knuuttila

Leif Leiden

Jouni Takakarhu

Jari Aarila

Anders E Nymark

Hans-Bertil Martinsson

Ari Palmroos

Antero Ahvenainen

Bill Gustafsson

Laila Rogestedt

Markku Asumalahti

Rune Nygaard

Arne Syre

Svein Eggen

Ilka Vaara

Kristen Kjeldsen

Bengt Hagstrom

Conventional coating compositions have the disadvantage of being insufficiently coatable and having an unsatisfactory environmental stress cracking resistance. Now a coating composition has been found which has both good coating processability and environmental stress cracking resistance. It comprises a multimodal ethylene polymer, which contains from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C -C &agr;-olefin repeating units, has a density of between 0.915 g/cm and 0.955 g/cm , and is a blend of at least a first ethylene polymer having a first average molecular weight and a first molecular weight distribution and a second ethylene polymer having a second average molecular weight, which is higher than said first average molecular weight, and a second molecular weight distribution, said blend having a third average molecular weight and a third molecular weight distribution.

Coating composition

Polyethylene composition

A method of compounding a multimodal, preferably a bimodal polymer composition comprising a low molecular weight ethylene polymer and a high molecular weight ethylene polymer is described. The composition is compounded during a relatively long time at a low temperature which lies in a narrow temperature range including the melting point of the low molecular weight ethylene polymer. More particularly, the polymer composition is compounded, without addition of a beat transfer medium, in a temperature range from about 10.degree. C. below to about 10.degree. C. above the melting point of the low molecular weight ethylene polymer during a time of more than 10 seconds. The viscosity ratio between the ethylene polymers in said temperature range preferably is from about 5:1 to about 1:5.

Method of compounding a multimodal polymer composition

A process for producing polyethylene compositions in the presence of a catalytic system of ethylene polymerizing catalyst and cocatalyst in a multistage continuous reaction sequence consisting of successive liquid phase and gas phase polymerizations is disclosed. In the first step of the process, ethylene and optionally hydrogen and comonomer are polymerized in a first loop reactor in a low boiling hydrocarbon medium in the presence of ethylene polymerizing catalyst and cocatalyst. The reaction mixture is then removed and then transferred to a second loop reactor where polymerization is continued by addiing ethylene, hydrogen and optionally inert hydrocarbon, comonomers and cocatalysts. Thereafter, the reaction mixture is removed from the second loop reactor along with an essential part of the reaction medium and transferred to a gas phase reactor where polymerizing is continued in the presence of added ethylene and optionally hydrogen, comonomers and cocatalysts to form an end product. The residence time and reaction temperature being such that the proportion of the ethylene polymer produced in the first loop reactor to the end product of the process is between 1-20%.

Process for preparing polyethylene

The invention relates to a new bis(trialkylsilyl) chromate of the formula ##STR1## where n is approximately 1-2. Such a compound can be prepared by causing a corresponding silyl halide to react with silver chromate. The product is especially suitable for the polymerization and copolymerization of ethylene, the formed polymer having a high molar mass and a wide molar mass distribution.

Transition-metal based catalyst for the polymerization and

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Kerava, Finland

Aimo Sahila