Borealis Technology Oy

Borealis A/s

Jussi Laurell

Bill Gustafsson

Jarmo Lindroos

Solveig Johansson

Ruth Dammert

Marja Ora

Arja Lehtinen

Elisabeth Ribarits

Mats B&auml;ckman

Eeva-Leena Heino

Teija Sihvonen

Jari Aaril&auml;

Erik Van Praet

Bernt-ANGke Sultan

Matti Hirvensalo

A multimodal polymer composition for pipes is disclosed as well as a pipes made thereof. The polymer is a multimodal polyethylene with a density of 0.930-0.965 g/cm , and a viscosity at a shear stress of 747 Pa of at least 650 Pa.s, said multimodal polyethylene comprising a low molecular weight (LMW) ethylene homopolymer fraction and a high molecular weight (HMW) ethylene copolymer fraction, said HMW fraction having a weight ratio of the LMW fraction to the HMW fraction of (35-55):(65-45). Preferably, the multimodal polyethylene has a viscosity at a shear stress of 2.7 kPa of 260-450 kPa.s; and a shear thinning index (SHI) defined as the ratio of the viscosities at shear stresses of 2.7 and 210 kPa, respectively, of SHI &equals;50-150, and a storage modulus (G&prime;) at a loss modulus (G&Prime;) of 5 kPa, of G&prime; &gE;3000 Pa. The pipe is made of the multimodal polymer composition and withstands a stress of 8.0 MPa gauge during 50 years at 20&deg; C. (MRS8.0). Preferably, the pipe has a rapid crack propagation (RCP) S4-value, determined according to ISO 13477:1997(E), of &minus;5&deg; C. or lower and a slow crack propagation resistance, determined according to ISO 13479:1997, of at least 500 hrs at 4.6 MPa/80&deg; C. The polymer composition affords good non-sagging properties to pipe made thereof.

Polymer composition for pipes

A process for the reduction of reactor fouling at radical initiated high pressure polymerisation of ethylene (co)polymers is described. The process is characterised in that an adhesion reducing silicon containing compound is added to the polymerisation reactor, preferably in an amount of 0.001-3% by weight, based on the amount of polymer produced. Preferably the silicon containing compound is hexadecyl trimethoxy silane.

Process for the reduction of reactor fouling

The present invention relates to a flame retardant composition comprising (A) a polymer which includes a copolymer of ethylene and at least one other comonomer including a vinyl unsaturated polybishydrocarbylsiloxane; and (B) an inorganic filler comprising at least one member selected from the group consisting of oxides, hydroxides and carbonates of aluminium, magnesium, calcium and barium. It also relates to a cable or wire comprising such a composition.

Flame retardant composition

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Borgå, Finland

Jussi Laurell