Stretched polyethylene multilayer film
AssigneeIdemitsu Petrochemical Co., Ltd.
InventorHisazumi Watanabe
Life of this patent
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Abstract
A stretched polyethylene multilayer film prepared by stretching a laminated film comprising a layer of an ethylene-.alpha.-olefin copolymer (A) having a melt index of 6 to 50 g/10 min and a layer of an ethylene-.alpha.-olefin copolymer (B) having a melt index of not less than 0.1 g/10 min and less than 6 g/10 min, by 2 to 7 times, both lengthwise and crosswise, has excellent low-temperature heat-sealability, excellent pin hole resistance, high mechanical strength, including excellent impact resistance, and good applicability to various processing machines, such as laminating machines, bag-making machines and automatic filling machines, and is suitable for use as packaging films and sealant materials for multilayer films.
Claims6
A stretched polyethylene multilayer film which exhibits excellent low-temperature heat-sealability and which is prepared by stretching a laminated film consisting essentially of
- two outer layers of an ethylene-.alpha.-olefin copolymer (A) having a melt index of not less than 6 g/10 min and not more than 50 g/10 min and one intermediate layer of an ethylene-.alpha.-olefin copolymer (B) having a melt index of not less than 0.1 g/10 min and less than 6 g/10 min, by 2 to 7 times both lengthwise and crosswise, and thereafter heat treating the stretched polyethylene multilayer film at a temperature of 80.degree. to 140.degree. C., wherein the ethylene-.alpha.-olefin copolymer (A) is a copolymerization product of ethylene and an .alpha.-olefin of 4 to 20 carbon atoms and has a density of 0.891 to 0.925 g/cm.sup.3 and the ethylene-.alpha.-olefin copolymer (B) is a copolymerization product of ethylene and an .alpha.-olefin of 4 to 20 carbon atoms and has a density of 0.910 to 0.960 g/cm.sup.3, and wherein the ratio of the thickness of each layer of the ethylene-.alpha.-olefin copolymer (A) and the thickness of the layer of the ethylene-.alpha.-olefin (B), (A/B), is not less than (2/96), the ratio of the total thickness of the layers of the ethylene-.alpha.-olefin copolymer (A) and the thickness of the layer of the ethylene-.alpha.-olefin copolymer (B), (A+A)/(B), is from 4/96 to 98/2, and the ratio of the thickness of each layer of the ethylene-.alpha.-olefin copolymer (A) and the total thickness of the layers of the ethylene-.alpha.-olefin copolymer (A) and the layer of the ethylene-.alpha.-olefin copolymer (B), A/(A+B+A), is not less than 2/100.
Dependencies are inferred from the claim text.