Hdpe polymer composition
AssigneeBorealis Technology Oy
InventorsAnn Kristen Lindahl, Harry Oysaed, Roger Goris
Life of this patent
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Abstract
HDPE compositions comprising a bimodal polymer and a nucleating agent, for producing moulded articles with increased E-modulus and high ESCR, and the use of such compositions in the production of moulded articles.
Claims32
An HDPE composition comprising an ethylene homopolymer or an ethylene alpha-olefin copolymer for producing moulded articles with increased E-modulus and high ESCR, wherein the polymer is a bimodal polymer produced in a multistage process comprising
- i) a low molecular weight ethylene polymer and
- ii) a high molecular weight ethylene polymer or copolymer and a nucleating agent.
A composition according to any preceding claim, characterized in that the density is between 910 and 980 kg/m3.
A composition according to any preceding claim, characterized in that the density is between 945 and 975 kg/m3.
A composition according to any preceding claim, characterized in that the melt index MFR21.6 measured at 190° C. under 21.6 kg load is between 1 and 1000 g/10 min.
A composition according to any preceding claim, characterized in that the polymer composition comprises 5-95% of said low molecular weight ethylene polymer and 95-5% of said high molecular weight ethylene polymer or copolymer.
A composition according to any preceding claim, characterized in that the number average molecular weight Mn is between 1,000 and 20,000 g/mole.
A composition according to any preceding claim, characterized in that the weight average molecular weight Mw is between 50,000 and 500,000 g/mole.
A composition according to any preceding claim, characterized in that the polydispersity index Mw/Mn is between 5 and 75.
A composition according to any preceding claim wherein the nucleating agent contains an organic group and a polar group and is insoluble in the HDPE.
A composition according to any preceding claim, characterized in that the nucleating agent is present in an amount of between 1 and 10,000 ppm.
A composition according to any preceding claim wherein the HDPE has been produced by a process comprising catalytically homopolymerizing ethylene in the liquid phase in an inert hydrocarbon medium in a loop reactor, passing the polymer product from the loop reactor to a gas phase reactor and there continuing the polymerization in the presence of ethylene and further catalyst to obtain a bimodal product of which said polymer from the loop reactor constitutes 20-90% weight.
A composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a weight average molecular weight of between 5,000 and 50,000 g/mole.
A composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a melt index MFR2 measured under 2.16 kg load of between 50 and 2,000 g/10 min.
A composition according to any preceding claim, characterized in that the low molecular weight ethylene polymer has a density between 960 and 980 kg/m3.
A composition according to any preceding claim, characterized in that the high molecular weight ethylene polymer or copolymer has a weight average molecular weight of between 300,000 and 1,000,000 g/mole.
A composition according to any preceding claim, characterized in that the high molecular weight ethylene copolymer has a comonomer content of 0.7 to 7.0 mole %.
Use of a bimodal HDPE composition comprising:
- iv) a low molecular weight ethylene polymer;
- v) a high molecular weight ethylene polymer or copolymer;
- and
- vi) a nucleating agent;
- for producing moulded articles with increased E-modulus and high ESCR.
Dependencies are inferred from the claim text.