Heat-Shrinkable Polyester Film Roll
Patent #: 6,958,178
Inventor(s): Satoshi Hayakawa, Norimi Tabota, Yoshinori Takegawa, Katsuya Ito, Shigeru Komeda and Katsuhiko Nose
Company: Toyo Boseki Kabushiki Kaisha
A heat-shrinkable polyester film roll was issued a patent. The roll includes an alkali-earth metal compound and a phosphorus compound, at an alkali-earth metal atom M2 content of 20-400 ppm (mass basis) and a phosphorus atom P content of 5-350 ppm (mass basis) in the film. When square samples cut off from the film roll in a size of 10 cmx10 cm are immersed in hot water at 85° C for 10 seconds, and subsequently in water at 25° C for 10 seconds and withdrawn, the heat shrinkage percentage of the samples in the maximum shrinkage direction is 20% or more. The termination end of the rolled film—which is obtained from a steady region wherein physical properties of the film are stabilized in the firm-running direction—is designated as end . The initiation end is end . The first cut-off point of the sample is placed at a position 2 m or less inside of end above, and the final cut-off point at a position 2 m or less inside of end above. Several sample cut-off points are placed at an interval of about 100 m from the first cut-off point. Rectangular samples 20 cm in length in the maximum shrinkage direction of the film and 5 cm in width are cut off from the cut-off points. The variations in thickness of respective samples in the maximum shrinkage direction are measured, The thickness distribution width of each sample represented by the following formula is 7% or less. Thickness distribution width = (Maximum thickness - Minimum thickness)/Average thickness x 100.
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