Sealable and Peelable Polyester Film
AssigneeCryovac, Inc.
InventorsForloni ROBERTO, Serena STRACUZZI
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Abstract
The invention discloses bi-axially oriented coated polyester films having high tear initiation resistance and comprising a polyester base film and a heat sealable coating, said heat sealable coating comprising one or more amorphous copolyester(s) comprising units of terephthalic acid, naphthalene dicarboxylic acid and at least one diol. The films are heat-sealable and peelable to polyester and aluminium containers. The invention also relates to a process for the manufacturing of such films, to the use of said films in food packaging and to the packages obtained therefrom.
Claims21
1) A bi-axially oriented coated polyester film comprising a polyester base film and a heat sealable coating wherein the heat sealable coating comprises one or more amorphous copolyester(s) comprising units of terephthalic acid, naphthalene dicarboxylic acid and at least a diol, and wherein the heat sealable coating contains from 20 to 50% by weight of terephthalic acid units and from 5 to 25% by weight of naphthalene dicarboxylic acid units,
- the bi-axially oriented coated polyester film having a tear ratio, between the tear initiation force measured according to ASTM D-1004 and the coated film total thickness, of at least 37 gf/micron in at least one of longitudinal and transverse directions.
13) A process for the manufacture of a film comprising the following steps:
- i) providing a monoaxially or biaxially oriented polyester base film having a tear ratio between the tear initiation force measured according to ASTM D-1004 and the base film having a total thickness of at least 37 gf/micron in at least one of longitudinal and transverse directions,
- ii) coating the monoaxially or biaxially oriented polyester base film by applying a heat sealable coating comprising at least one amorphous copolyester(s) comprising units of terephthalic acid, naphthalene dicarboxylic acid and at least a diol, wherein the heat sealable coating contains from 20 to 50% by weight of terephthalic acid units and from 5 to 25% by weight of naphthalene dicarboxylic acid units, to one surface of the polyester base film, thus providing a mono or biaxially oriented coated polyester film
- iii) optionally, in case a monoaxially oriented coated film is obtained in one of the longitudinal or the transverse direction, orienting the monoaxially oriented coated film in the other of the longitudinal or the transverse direction, thus providing a biaxially oriented coated polyester film, and
- iv) drying the biaxially oriented coated polyester film.
17) A package comprising a container, a product, and a lid sealed onto the container, wherein the lid comprises a biaxially oriented coated polyester film comprising a polyester base film and a heat sealable coating wherein the-heat sealable coating comprises one or more amorphous copolyester(s) comprising units of terephthalic acid, naphthalene dicarboxylic acid and at least a diol, and wherein the heat sealable coating contains from 20 to 50% by weight of terephthalic acid units and from 5 to 25% by weight of naphthalene dicarboxylic acid units, the biaxially oriented coated polyester film having a tear ratio, between the tear initiation force measured according to ASTM D-1004 and the coated film total thickness, of at least 37 gf/micron in at least one of longitudinal and transverse directions.
Dependencies are inferred from the claim text.