Toyo Boseki Kabushiki Kaisha

Seizo Takabayashi

Norimi Tabota

Tsutomu Isaka

Tsutomu Oko

Masatoshi Hashimoto

Kuniharu Mori

Shinichiro Okumura

Hideki Ito

Mitsuo Inoue

Hiroshi Nagano

Shigeji Konagaya

Koji Yamada

Atsuhiko Ohtsuka

Hiroaki Esaki

A heat-shrinkable polyester film having a shrinkability in hot water (hereinafter referred to as a hot-water shrinkability) at 95&deg; C. for 10 seconds ranging from 30% to 50% in at least one direction (hereinafter referred to as direction (A)) and ranging from 25% to 45% in a direction (hereinafter referred to as direction (B)) perpendicular to said at least one direction, wherein a difference &Dgr;HS between the hot-water shrinkability in direction (A) and the hot-water shrinkability in direction (B) (ie., &Dgr;HS&equals;&verbar;hot-water shrinkability in direction (A)&mdash;hot-water shrinkability in direction (B)&verbar;) is 10% or smaller, is useful as a wrapping material, mainly as a covering material for the openings of vessels used for packing noodles, puddings, salads, and other foods.

Heat-shrinkable polyester films

In a thermo-shrinkable polyester film, the thermal shrinkage ratio in a main shrinking direction is about 20% or more after being treated in water of about 70.degree. C. for about seconds, about 35 to about 55% after treated in water of about 75.degree. C. for about 5 seconds, and about 50 to about 60% after being treated in water of about 80.degree. C. for about 5 seconds. After the film is shrunk by about 5% by treatment in water of about 75.degree. C. for about 10 seconds, the probability of the elongation at rupture of the film in the direction perpendicular to the main shrinking direction being about 20% or less, is about 10% or less. The ratio of .tau..sub.1 /.tau..sub.2 is about 0.05 to about 0.45, where .tau..sub.2 is the stress of shrinkage in a main shrinking direction of the film at about 90.degree. C., and .tau..sub.1 is the stress of shrinkage in a direction perpendicular to the main shrinking direction of the film at about 90.degree. C. The sealing strength of the film is about 1.2 kg/15 mm of width or more.

Thermo-shrinkable polyester film

Heat-shrinkable polyester films having a heat shrinkability of 30% or more, preferably 40% or more, in the direction of major shrinkage after treatment in hot water at 80.degree. C. for 30 seconds, the ratio of heat shrinkability in the direction of major shrinkage after treatment in hot water at 80.degree. C. for 5 seconds to heat shrinkability in the direction of major shrinkage after treatment in hot water at 80.degree. C. for 30 seconds being 0.8 or less, preferably 0.7 or less. The heat-shrinkable polyester films are suitable for label applications because of their particular heat-shrinkable properties such that not only do they scarcely cause longitudinal sinking when shrunk but also they have very few wrinkles, shrinkage spots and strains remaining after shrinkage.

Growing community of inventors

Inuyama, Japan

Seizo Takabayashi