Bottles and jars – Ejecting – Siphon type
Patent
1981-06-02
1983-08-16
Lesmes, George F.
Bottles and jars
Ejecting
Siphon type
426127, 428 35, 4284752, 428480, 428910, B65D 2300
Patent
active
043986420
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to multi-ply vessels having excellent gas barrier properties and high transparency, and a method for the production thereof.
Thermoplastic polyester resins, mainly polyethylene terephthalate, have widely been used for various vessels and packaging materials in the form of film and sheet because of their excellent mechanical properties, gas barrier properties, chemical resistance, scent maintenance and hygienic qualities. Particularly, with progress of blow molding techniques, especially biaxial orientation blow molding techniques, these resins are frequently employed for the production of hollow vessels such as bottles and cans. That is, for example, thermoplastic polyester bottles produced by a biaxial orientation blow molding technique are disclosed in U.S. Pat. No. 3,733,309.
However, the vessels produced from thermoplastic polyester resins, mainly polyethylene terephthalate, by a biaxial orientation technique do not necessarily satisfy all performances. Particularly, these vessels are not suitable for packing foods which require good gas barrier properties because they have poor gas barrier properties against oxygen.
A saponified ethylene-vinyl acetate copolymer, a styrene-acrylonitrile copolymer and the like have hitherto been known as thermoplastic resins having high gas barrier properties, but the vessels made from these resins alone are inferior in impact resistance or are not favorable from hygienic viewpoint and hence, can not be used in practice.
In Japanese Patent Laid Open Publication No. 108162/1978, there is disclosed that a vessel having gas barrier properties can be produced by orienting and blow-molding a vessel preform (hereinafter referred to as parison) having two-layer structure composed of a thermoplastic polyester resin and a saponified ethylene-vinyl acetate copolymer. However, when a saponified ethylene-vinyl acetate copolymer is used, the parison becomes opaque during formation thereof and shows remarkably lowered transparency because the copolymer itself is a crystalline resin. Of course, when the parison is oriented to make the wall thin, transparency thereof is somewhat improved, but the non-oriented parts, such as bottom part of a bottle, are still opaque, which causes poor appearance.
When a multi-ply vessel is produced by using a styrene-acrylonitrile copolymer, known as a resin having high gas barrier properties, together with a thermoplastic polyester resin, a parison does not lose transparency during formation thereof because the copolymer itself is a non-crystalline resin. However, the copolymer has a high glass transition temperature and hence, the parison can not be sufficiently oriented at an orienting temperature suitable for the polyester resin. Moreover, because of the non-crystallizability of the copolymer, no crystallization of the copolymer is induced by orientation and thereby, the vessel is unfavorably deformed by orientation release stress.
An object of the present invention is to provide a vessel having gas barrier properties against oxygen without losing properties of a thermoplastic polyester resin such as excellent mechanical properties, transparency, chemical resistance, hygienic qualities and the like. Another object of the present invention is to provide a vessel having excellent dimensional stability and form retention. A further object of the present invention is to provide a vessel having excellent adhesion between layers of the multi-ply structure thereof. These and other objects and advantages of the present invention will by apparent to those skilled in the art from the following description.
The vessel of the present invention has multi-ply structure composed of at least two kinds of synthetic resins. The multi-ply vessel comprises an inner layer composed of a thermoplastic polyester resin, a middle layer composed of a metaxylylene group-containing polyamide resin and an outer layer composed of a synthetic resin having impermeability to moisture, said layers of the thermoplastic polyester resin and the metaxylylene
REFERENCES:
patent: 3686069 (1972-08-01), Winkler et al.
patent: 3874989 (1975-04-01), Stange et al.
patent: 4180614 (1979-12-01), Angelo et al.
Hama Yoshihisa
Okudaira Tadashi
Sugihara Shigeharu
Tsuboi Akio
Buffalow E. Rollins
Lesmes George F.
Toyo Boseki Kabushiki Kaisha
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