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US 9,518,195 B2Granted
Biaxially stretched polyester film and method for producing same
AssigneeUnitika Ltd.
InventorsTakayoshi Okuzu, Tomoharu Suzuki
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AssigneeUnitika Ltd.
InventorsTakayoshi Okuzu, Tomoharu Suzuki
Estimating the term…
A biaxially stretched polyester film, being a biaxially stretched film including a modified polybutylene terephthalate (modified PBT) and polyethylene terephthalate (PET), wherein a mass ratio (modified PBT/PET) between the modified PBT and PET is 20/80 to 5/95, the modified PBT is a PBT containing 5 to 20% by mass of a polytetramethylene glycol unit having a molecular weight of 600 to 4,000, the amount of tetrahydrofuran (THF) generated by heat treating the biaxially stretched film in a helium gas atmosphere at 180° C. for 30 minutes is 50 μg/g or less, and the biaxially stretched film has tear linearity in a lengthwise direction thereof.
A biaxially stretched polyester film, being a biaxially stretched film comprising a modified polybutylene terephthalate (modified PBT) and polyethylene terephthalate (PET), wherein a mass ratio (modified PBT/PET) between the modified PBT and PET is 20/80 to 5/95, the modified PBT is a PBT containing 5 to 20% by mass of a polytetramethylene glycol unit having a molecular weight of 600 to 4,000, an amount of tetrahydrofuran (THF) generated by heat treating the biaxially stretched film in a helium gas atmosphere at 180° C. for 30 minutes is 50 μg/g or less, and the biaxially stretched film has tear linearity in a lengthwise direction thereof.
Dependencies are inferred from the claim text.