Stock material or miscellaneous articles – Composite – Of polyester
Patent
1997-01-15
1998-06-23
Raimund, Christopher
Stock material or miscellaneous articles
Composite
Of polyester
428483, 5283086, 5282955, B32B 2706
Patent
active
057703175
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a copolyester film suitable for a copolyester wrapping film being mainly used for wrapping foods, and to a copolyester composition film having an excellent self-adherence property.
BACKGROUND ART
A wrapping film is generally used for the food preservation in homes and in business uses, and also in the case of heating foods using a microwave oven.
A wrapping film is required to have a barrier property for an odor at a food preservation and also is required to have a high heat resistance without being broken by heating in a microwave oven.
Furthermore, a wrapping film is required to have a proper flexibility for efficiently wrapping or tightly closing up foods, etc., and further a wrapping film is desired to have a self-adherence property.
Hitherto, as a wrapping film, films of a vinylidene chloride copolymer and polyethylene have been generally used.
However, the vinylidene chloride series wrapping film is insufficient in the heat resistance such as causing breaking of the film when the wrapped material with the film is too heated for a long time in a microwave oven, and shows a large heat shrinkage. Also, the polyethylene series wrapping film is further insufficient in the heat resistance and inferior in the barrier property for odor. Accordingly, the development of a new film, which has a high heat resistance and an excellent barrier property for odor, is flexible, and preferably has a self-adherence property, has been desired and also the development of a new polyester film having the foregoing properties has been expected from the point of a food sanitation.
Hitherto, many copolyester films obtained by copolycondensation of components capable of forming flexible copolymers have been proposed. For example, many copolyesters each having a low melting point and low elasticity composed of dicarboxylic acids such as mainly terephthalic acid and a selected diol, and also many film thereof have been proposed. However, since they aim at being used as adhesives, they are provided as non-oriented films and do not have the characteristics suitable for wrapping films.
For using wrapping films, a polybutylene terephthalate (PBT) film and a film of a copolyester composed of a long-chain dicarboxylic acid and polytetramethylene glycol have been proposed but these films have not yet simultaneously satisfied the heat resistance, the barrier property for odor, the flexibility, and the self-adherence property required for a wrapping film.
JP-A-61-276820 (U.S. Pat. No. 4,725,483 or EP-86304146.3) (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses a copolyester film composed of at least 85 mole % of terephthalic acid, from 65 to 97 mole % of 1,4-butanediol, and from 3 to 35 mole % of polyethylene glycol having a molecular weight of from 106 to 550. The polyester film has the main endothermic peak at a temperature of from 160.degree. C. to 220.degree. C. and the subsidiary endothermic peak at a temperature of from 30.degree. C. to 80.degree. C., and the area of the portion having the side endothermic peak of not less than 40.degree. C. is in the range of from 3 to 20% of the area of the main endothermic peak.
JP-A-59-11383 discloses a hot melt adhesive composed of a polyester having a melting point of from 80.degree. C. to 160.degree. C. and composed of from 90 to 50 mole % of terephthalic acid, from 30 to 75 mole % of 1,4-butanediol, from 70 to 25 mole % of diethylene glycol, and polytetramethylene glycol having a molecular weight of from 500 to 6,000 in an amount of from 0.1 to 5 mole % based on the total acid components.
DE-4027353 (JP-A-5-194720) discloses a wrapping film for foods being heated in a microwave oven, which is composed of terephthalic acid and/or isophthalic acid, an alkylene glycol having a carbon atom number of from 1 to 6, and a polyoxyalkylene glycol having a weight average molecular weight of from 900 to 4,000.
JP-A-4-306239 discloses a wrapping film for wrapping foods, which is at least uniaxia
Takaya Katsuhiko
Ueno Tetsuo
Asahi Kasei Kogyo Kabushiki Kaisha
Raimund Christopher
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