Singlelayer and multilayer polyolefin foam pipes
AssigneeBorealis AG
InventorsAchim Hesse, Tony Lindstroem, Carl-Gustaf Ek, Cecilia Rydin
Life of this patent
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Abstract
Singlelayer and multilayer polyolefin foam pipes with improved compression resistance have a polyolefin foam layer which consists of mixtures of modified propylene polymers having strain hardening behaviour of propylene homopolymers with a stereospecifity index >98% or propylene copolymers with a stereospecifity index of the homopolymer matrix of >96%. The polyolefin foam pipes are coated steel pipes for transporting crude oil or gas products or district heating applications, singlelayer pipes for insulation purposes and for non- or low-pressure applications and multilayer plastic pipes for the transportation of hot or cold fluids.
Claims17
Singlelayer or multilayer polyolefin foam pipe with improved compression strength where at least one layer is comprised of a polyolefin foam layer, characterized in that the polyolefin foam layer, having a density of 50 to 850 kg/m3, comprises mixtures of
- A) 5 to 80% by weight of a compound A, which is selected from modified propylene polymers with a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of 0.2 to 10 g/10 min at 230° C./2.16 kg, which modified propylene polymers have strain hardening behaviour, and mixtures of these modified propylene polymers,
- B) 20 to 95% by weight of a compound B which is selected from propylene homopolymers with a stereospecifity index >98% and a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of 0.1 to 10 g/10 min at 230° C./2.16 kg and copolymers from 80.0 to 99.9% by weight of propylene and 0.1 to 20.0% by weight of ethylene or α-olefins with 4 to 18 carbon atoms with a stereospecifity index of the propylene homopolymer matrix of >96% and a melt index of 0.1 to 10 g/10 min at 230° C./2.16 kg, and mixtures of these propylene homopolymeres and/or copolymers, and,
- C) optionally, usual amounts of stabilizers and/or processing aids and/or antistats and/or pigments and/or nucleating agents and/or fillers as auxiliary substances.
A process for producing polyolefin foam coated steel pipes with improved compression resistance, comprising a steel pipe core, an intermediate polyolefin foam layer and an unfoamed outer polymer layer, by coating extruder/rotating steel pipe technology or by crosshead die pipe coating technology, characterized in that the polyolefin foam layer has a density of from 400 to 850 kg/m3 and the polyolefins used in foam coating are mixtures of
- A) 5 to 80% by weight of a compound A, which is selected from modified propylene polymers with a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of strain hardening behaviour, and mixtures of these modified propylene polymers,
- B) 20 to 95% by weight of a compound B which is selected from propylene homopolymers with a stereospecifity index >98% and a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of 0.1 to 10 g/10 min at 230° C./2.16 kg and copolymers from 80.0 to 99.9% by weight of propylene and 0.1 to 20.0% by weight of ethylene or α-olefins with 4 to 18 carbon atoms with a stereospecifity index of the propylene homopolymer matrix of >96% and a melt index of 0.1 to 10 g/10 min at 230° C./2.16 kg, and mixtures of these propylene homopolymeres and/or copolymers, and,
- C) optionally, usual amounts of stabilizers and/or processing aids and/or antistats and/or pigments and/or nucleating agents and/or fillers as auxiliary substances,
- whereby the melt of said mixtures in the foam coating steel pipe process contains up to 12% by weight, based on the polyolefin mixture, of chemical blowing agents that split off gas, or hydrocarbons, halogenated hydrocarbons and/or gases as blowing agents and whereby the steel pipes are preheated to a temperature preferably ranging from 170 to 230° C. and the foam coating extruder has a temperature profile preferably ranging from 175 to 250° C.
A process for producing polyolefin foam plastic pipes with improved compression resistance by coextrusion or injection molding or blow molding, where at least one layer is comprised of a polyolefin foam layer, characterized in that the polyolefin foam layer has a density of from 50 to 850 kg/m3 and the polyolefins used for the foamed polyolefin layer are mixtures of
- A) 5 to 80% by weight of a compound A, which is selected from modified propylene polymers with a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of 0.2 to 10 g/10 min at 230° C./2.16 kg, which modified propylene polymers have strain hardening behaviour, and mixtures of these modified propylene polymers,
- B) 20 to 95% by weight of a compound B which is selected from propylene homopolymers with a stereospecifity index >98% and a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, preferably of 0.1 to 10 g/10 min at 230° C./2.16 kg and copolymers from 80.0 to 99.9% by weight of propylene and 0.1 to 20.0% by weight of ethylene or α-olefins with 4 to 18 carbon atoms with a stereospecifity index of the propylene homopolymer matrix of >96% and a melt index of 0.1 to 10 g/10 min at 230° C./2.16 kg, and mixtures of these propylene homopolymeres and/or copolymers, and,
- C) optionally, usual amounts of stabilizers and/or processing aids and/or antistats and/or pigments and/or nucleating agents and/or fillers as auxiliary substances,
- whereby the melt of said mixtures in the coextrusion or injection molding or blow molding foam process contains up to 12% by weight, based on the polyolefin mixture, of chemical blowing agents that split off gas, or hydrocarbons, halogenated hydrocarbons and/or gases as blowing agents.
Dependencies are inferred from the claim text.