Polypropylene coated paper and paperboard
AssigneeStora Enso OYJ
InventorVille Ribu
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Abstract
The present invention relates to paper or paperboard comprising cellulose fibers, said paper or paperboard comprising at least one coating layer formed by extrusion coating of a PP (polypropylene) resin, characterized in that the PP resin comprises at least 50% by weight of a branched PP copolymer having a density in the range of 890-910 kg/m3 (as determined according to ISO 1183), a melting temperature in the range of 155-170° C. (as determined according to ISO 11357-3), and a melt flow rate (230° C./2.16 kg) in the range of 10-15 g/10 min (as determined according to ISO 1133), and wherein the PP resin is applied to the paper or paperboard at a grammage of less than 30 g/m2.
Claims16
A paper or paperboard comprising:
- cellulose fibers, and
- at least one coating layer formed by extrusion coating of a PP (polypropylene) resin,
- wherein the PP resin comprises at least 50% by weight of a branched PP copolymer having a density in a range of 898-902 kg/m3 (as determined according to ISO 1183), a melting temperature in a range of 160-164° C. (as determined according to ISO 11357-3), and a melt flow rate (230° C./2.16 kg) in a range of 10-15 g/10 min (as determined according to ISO 1133),
- wherein said PP copolymer has been subjected to visbreaking, and,
- wherein the PP resin is applied to the paper or paperboard at a grammage of less than 30 g/m2.
A method for manufacturing a PP resin coated paper or paperboard substrate comprising cellulose fibers, said method comprising:
- a) providing paper or paperboard substrate,
- b) applying at least one layer of a molten PP resin to a surface of said substrate by extrusion coating,
- c) allowing the molten PP resin to cool down and solidify, and
- d) recovering the PP resin coated substrate,
- wherein the PP resin comprises at least 50% by weight of a branched PP copolymer having a density in a range of 890-910 kg/m3 (as determined according to ISO 1183), a melting temperature in a range of 155-170° C. (as determined according to ISO 11357-3), and a melt flow rate (230° C./2.16 kg) in a range of 10-15 g/10 min (as determined according to ISO 1133),
- wherein said PP copolymer has been subjected to visbreaking, and
- wherein the PP resin is applied to the substrate at a grammage of less than 30 g/m2.
Dependencies are inferred from the claim text.