Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Patent
1994-03-03
1997-05-13
Robinson, Ellis
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
428 355, 428 357, 428194, 428200, 428201, 428202, 428212, 428349, 426119, 426129, 426396, 53453, 53511, 53559, 156 69, 156292, 156581, 1565831, B32B 714, B30B 1534, B65D 8500
Patent
active
056290608
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to improved packaging with peelable lid and relates particularly, but not exclusively, to packaging of the plastics material type wherein there is a generally rigid base, and a potentially rupturable, flexible web of plastics material over the base and sealed to the base to define a space therebetween and wherein there is a relatively rigid lid sealed over the flexible web.
DESCRIPTION OF PRIOR ART
Hitherto, packaging of the above type has been produced. An example of such packaging is disclosed in U.S. Pat. No. 4,685,274 where A. J. M. Garwood is listed as the inventor. The packaging disclosed in the aforementioned U.S. patent specification relates to packaging whereby foodstuffs can be kept for a substantial period of time with enhanced keeping properties. Typically such packaging comprises a plastics material base, foodstuffs such as red meat placed on the base, a thin flexible web skin packaged to the base over the goods and a lid provided over the base to define a space between the lid and the plastics web. The space contains a gas for enhancing the keeping properties of the meat by permeating through the flexible web. The aforementioned specification also makes mention of the fact that the lid can be peelable from the base whereby to allow gases such as oxygen to then permeate through the flexible web to enhance the restoration of a bright red colour to the meat which may have turned dark brown/purple during the storage life of the meat in the package.
Thus, whilst the present invention has particular application to packaging of the above type it is not intended to be limited to such packaging and has application generally to packaging where goods are packaged to a base by a thin flexible web and wherein a lid is required to be placed over the thin flexible web and subsequently stripped therefrom without rupturing the thin flexible web.
In the embodiments of the packaging described above in relation to the U.S. patent specification, we have experienced rupturing of the thin flexible web when the lid is peeled from the package. This rupturing occurs at the edges of the seal which are innermost relative to the package during the peeling process.
OBJECT AND STATEMENT OF THE INVENTION
It is an object of the present invention to provide an improved method and product whereby rupturing of the thin flexible web around the seal is inhibited during the peeling process.
This desired end result can be achieved by providing the seal with a peelable adhesion gradient across the width of the seal and wherein the greatest adhesion is outermost of the package.
Therefore in accordance with the first broad aspect of the present invention there may be provided a method of sealing a peelable lid to a package which contains a base and a potentially rupturable flexible web of plastics material covering and held to the base which together define a space therebetween, said method comprising the steps of: like seal which extends around the perimeter of said space so said lid will be sealed at the same region as the thin flexible web is held to said base, said sealing being by a thermosealing process which provides a temperature gradient across the width of the strip like seal during the sealing process, width of said strip like seal there being a lower adhesion adjacent the space so that when said lid is stripped from said package, the stripping of said lid will be unlikely to rupture said thin flexible web.
In accordance with a further broad aspect of the present invention there may be provided a package comprising a base, a potentially rupturable flexible web of plastics material covering said base and adhered to said base to define a space therebetween, and a lid sealed to said flexible web at the same region as said flexible web is adhered to said base, the sealing of said lid to said flexible web being by way of a strip like seal which extends around said space, and wherein there is a peelable adhesion gradient across the width of the strip, there being a lower adhesi
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Dye Rena L.
Robinson Ellis
Seawell North America Inc.
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