Thermo-shrinkable polyester type film and tube and processing method for preparing the tube
AssigneeToyo Boseki Kabushiki Kaisha
InventorsTsutomu Isaka, Toshihiro Yamashita
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Abstract
A thermo-shrinkable polyester type film having the following shrinking properties: a shrinking ratio in one axis is not less than 30% at 80.degree. C. and not less than 50% at 100.degree. C., and a shrinking ratio in a perpendicular axis to the former axis shows the minimum value at a temperature range of 80.degree..+-.25.degree. C., and the process therefor. This film shows an excellent shrinking properties for packaging.
Claims14
A thermo-shrinkable polyester type film which is obtained from a material selected from the group consisting of a polyester having a glass transition temperature of no less than 35.degree. C., a polyester copolymer having a glass transition temperature of no less than 35.degree. C., and a mixture of both of said polyester and polyester copolymer with at least one other polymer, wherein said film has the following shrinking properties:
- a shrinking ratio in the one axis is not less than 30% of 80.degree. C. and not less than 50% at 100.degree. C., and
- a shrinking ratio in perpendicular axis to the former axis is not more than 15% in the range of 55.degree.-105.degree. C., and the minimum value of the shrinking ratio occurs at a temperature in the range of 55.degree.-105.degree. C.;
- and
- having an orientation factor of not more than 100.times.10.sup.-3.
A tube of a thermo-shrinkable polyester type film which has a jointed surface being jointed by at least one solvent or swelling agent having a solubility or swelling ability to a polyester and a solubility index of 8.0-13.8, and the following shrinking properties:
- a peripheral shrinking ratio is not less than 30% at 80.degree. C. and not less than 50% at 100.degree. C., and
- a longitudinal shrinking ratio is not more than 15% in the range of 55.degree.-105.degree. C., and the minimum value of the shrinking ratio occurs at a temperature in the range of 55.degree. to 105.degree. C.
A process for production of a tube from polyester type film which comprises:
- disposing a polyester type film having shrinking properties wherein a shrinking ratio in one axis is not less than 30% at 80.degree. C. and not less than 50% at 100.degree. C., and a shrinking ratio in a perpendicular axis to the former axis is not more than 15% in the range of 55.degree.-105.degree. C., and the minimum value of the shrinking ratio in the perpendicular axis occurs at a temperature in the range of 55.degree.-105.degree. C.,
- spreading at least one jointed surface of the film with a solvent or a swelling agent having a solubility or swelling ability to a polyester and a solubility parameter or 8.0-13.8, and
- jointing the surfaces to be jointed to give a tubular film before the solvent or swelling agent is dried.
A process for production of a tube from polyester type film which comprises:
- disposing a polyester type film having shrinking properties wherein a shrinking ratio in one axis is not less than 30% at 80.degree. C. and not less than 50% at 100.degree. C., and a shrinking ratio in a perpendicular axis to the former axis is not more than 15% in the range of 55.degree.-105.degree.C., and the minimum value of the shrinking ratio in the perpendicular axis occurs at a temperature in the range of 55.degree.-105.degree. C.,
- disposing an adhesive layer on entire or part of at least one surface to be jointed,
- spreading at least one surface with a solvent or a swelling agent having a solubility or swelling ability to a polyester and a solubility parameter of 8.0-13.8, and
- jointing the surfaces to be jointed to give a tubular film before the solvent or swelling agent is dried.
Dependencies are inferred from the claim text.