Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1989-03-23
1991-06-04
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
25218624, 25218625, 25218633, 25218828, 252383, 252385, 428483, 428 366, 428 358, 428219, 428332, C08K 500, C08K 509, B32B 2718, B65D 8126
Patent
active
050215159
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to packaging, especially packaging of oxygen-sensitive materials, most especially of foods and beverages.
BACKGROUND OF INVENTION
Packaging, whether rigid, semi-rigid, flexible, lidded, or collapsible, or a combination of these, serves not merely to contain the material being packaged but, depending on the nature of the material, to prevent ingress of harmful substances from the environment. Oxygen from the atmosphere has long been regarded as one of the most harmful substances for many packaged materials, especially foodstuffs.
Packaging made exclusively of glass or metal can provide an extremely good barrier both to egress of all substances from the package (especially water and carbon dioxide) and to ingress of all substances from the environment. Packaging made of polymers in whole or in part generally performs far less well in both these respects. This has restricted for many years the use of polymers in packaging, despite the great advantages of polymers. These advantages derive from the diversity of polymers themselves in mechanical, thermal, and optical properties and from the diversity and adaptability of fabrication techniques for polymers, allowing flexible bags, rigid containers, and clinging films to be made, the package wall being homogeneous, laminated, or coated. Compared with glass and metal packages, polymer packages are generally light and compared with glass are generally less breakable. There are also cost advantages with some polymers.
Polyethylene terephthalate is a major packaging polymer, used particularly for bottles for carbonated beverages. It is over twenty times less permeable than polypropylene while still having a practically significant permeability. There are extremely impermeable polymers such as copolymers of ethylene and vinyl alcohol, of vinylidene chloride and vinyl chloride, and of m-xylylenediamine and adipic acid ("MXD6"); but for practical or cost reasons these tend to be used as thin layers on or between polyethylene terephthalate or (in the case of MXD6) for blending with polyethylene terephthalate, in low percent quantities, still leaving practically significant permeability. For instance, oriented blends of polyethylene terephthalate (96%) and MXD6 (4%) are about 70% as permeable as polyethylene terephthalate. Chemical Abstracts, 1984, volume 100, abstract 100: 193165x, being an abstract of Japanese published patent application 58 160344, give some information on these blends.
We believe that there is considerable potential for extending the use of polymers by means of oxygen-scavenging systems. In these, oxygen reacts chemically as it is transmitted inwards towards the package contents. Accordingly, transmission of oxygen inwards to the package contents is reduced, not necessarily with any improvement in the performance of the package with respect to inward transmission of other substances such as nitrogen or water vapour or outward transmission of substances.
Among substances that we believe can then be more satisfactorily packaged with polymers we would particularly mention beers (especially lager beers), wines (especially white ones), fruit juices, some carbonated soft drinks, fruits, nuts, vegetables, meat products, baby foods, coffee, sauces, and dairy products. Almost all foods and beverages are likely to display some benefit.
Oxygen-scavenging implies consumption of a material incorporated in the wall of the package. This will be progressively consumed, so that the high barrier to oxygen must in principle be of limited duration. However, the deterioration of the barrier to oxygen is not necessarily commercially very significant. An advantage is obtained so long as the rate of such deterioration is not too great with respect to the time for which the deterioration can occur prior to consumption of the product. This will depend on the time from packaging to consumption and also on any relevant storage times of raw materials, fabricated packaging materials, and containers prior to their use in packaging
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Chemical Abstracts, vol. 100, 1984, p. 60, 193165X H. F. Mark, "Encyclopedia of Polymer Science and Engineering", vol. 2, 1985, pp. 84-85, (p. 85, Para. 3).
Cochran Michael A.
Folland Rickworth
Nicholas James W.
Robinson Melvin E. R.
CMB Foodcan plc
McDonald, Jr. T.
Michl Paul R.
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