Composite sheet for food container

Details Composite sheet for food container Composite sheet for food container

1997-11-26

2001-01-23

Thibodeau, Paul (Department: 1773)

Stock material or miscellaneous articles

Hollow or container type article

Polymer or resin containing

C428S036600, C428S036700, C428S036900, C428S036910, C428S412000, C428S474400, C428S475200, C428S475500, C428S475800, C428S476300

Reexamination Certificate

active

06177159

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a composite sheet for food containers for containing food or beverage which has excellent sealability, heat resistance, aroma proof and low-temperature impact resistance and which can be subjected to high-temperature sterilization.
Hitherto, as containers or packaging materials for packaging foods which are highly susceptible to oxygen gas without causing deterioration of the foods, synthetic resin containers or packaging materials prepared by the methods called vacuum forming or air-pressure forming from a laminate sheet of at most about 1 mm thick comprising polypropylene/ethylene-vinyl alcohol copolymer/polypropylene have been utilized as disposable containers.
These conventional containers have problems that they are not sufficient in aroma proof and flavor of foods is spoiled. For solving these problems, JU-B-5(1993)-8127 proposes to provide an aroma proof resin layer comprising a saturated polyester resin layer or polycarbonate resin layer as the innermost layer. According to this invention, there is obtained a container which can preserve foods without spoiling flavor by laminating in succession the aroma proof resin layer, a water vapor barrier resin layer, a gas barrier resin layer and a thermoplastic resin layer.
The flavor of foods is deteriorated with oxygen gas, and, besides, the flavor per se is adsorbed (absorbed) into the materials of containers or packaging materials or transmits through containers or the like, and thus the flavor of foods is spoiled. This causes deterioration of quality of contents. It is generally known that saturated polyester resins or polycarbonate resins are high in the effect to preserve the flavor.
The above-mentioned containers are filled with contents, sealed and heat treated in factories and then distributed to shops. Some of the commodities are stored at low temperatures during the stage of this distribution, and even in the case of distribution at room temperature, the temperature becomes considerably low in winter. The conventional containers lower in impact resistance during distribution at low temperatures, and cracks may occur in a part of the container. In this case, if the content is liquid, there is the possibility of the content leaking out of the container. Furthermore, there is the possibility of the content putrefying because gas barrier properties imparted to the container cannot be sufficiently exhibited.
Various proposals have also been made on containers improved in impact resistance at low temperatures, but composite sheets for food containers of high low-temperature impact resistance with having both the preservability and aroma proof of contents have not yet been disclosed.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a composite sheet for food container which has remarkable aroma proof and low-temperature impact resistance with having the performances of synthetic resin containers having gas barrier properties and capable of being subjected to high-temperature sterilization.
The present invention is a composite sheet for food containers which comprises (A) an aroma proof resin layer comprising a saturated polyester resin, a polycarbonate resin and a copolymer comprising three components of bisphenol A, diphenyl carbonate and 1,10-decanedicarboxylic acid (hereinafter referred to as “a three-component copolymer”) or a mixture of at least two of these three resins, (B) a polyamide resin layer, (C) a water vapor barrier resin layer, (D) a gas barrier resin layer and (E) a thermoplastic support resin layer, these layers being laminated in succession in order of A-B-C-D-E. If necessary, adhesive layers may be provided between A-B, B-C, C-D and D-C, respectively.


REFERENCES:
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patent: 5336549 (1994-08-01), Nishimoto et al.
patent: 5972447 (1999-10-01), Hata et al.
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patent: 2197254A (1988-05-01), None
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Database WPI, Section Ch, Week 9651, Class A18, AN 96-513896, JP 08 267 676A, Oct. 15, 1996, abstract.
Patent Abstracts of Japan, vol. 18, No. 616 (M-1710), Nov. 24, 1994, JP 06 238847A, Aug. 30, 1994.
Japanese Kokai JU-A 61('86)-115626.
Japanese Kokai JP-A 60('85)-68938.
Japanese Kokai JP-A 2('90)-204035.
JP-A 9('97)-327896.

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