Food or edible material: processes – compositions – and products – Processes – Packaging or treatment of packaged product
Reexamination Certificate
1999-07-19
2001-07-24
Cano, Milton (Department: 1761)
Food or edible material: processes, compositions, and products
Processes
Packaging or treatment of packaged product
C426S398000, C426S412000, C229S005810
Reexamination Certificate
active
06265009
ABSTRACT:
The present invention refers to a container which is manufactured by means of folding and sealing, and which is intended to be used in extremely humid conditions, such as in an autoclave or in a cooling tunnel, the container having at least one liquid absorbing layer. More specifically, the invention relates to a container, in which all the cut edges are protected.
Paper and board are cheap package materials. However, they also have drawbacks in rapidly loosing their mechanical strength properties when exposed to liquid or moisture, which results in that a container which comprises these materials becomes flabby and cumbersome. It has thus been necessary to improve the properties of these materials, either by coating or lamination.
A large group of known containers is thus manufactured from a laminated material comprising a strengthening base layer of a liquid absorbing material as well as a barrier layer of for example aluminium (Al-foil) which is applied against one side of the base layer and which gives the container the desired sealing properties. Furthermore, such a laminated material comprises an outer coating of plastic (usually polyethylene) so that the container easily can be sealed by means of what is called heat sealing.
A dimensional stable liquid impermeable packaging container is for example manufactured from a material web by the web being formed to a tube in such a way that the two longitudinal edges of the web are permanently joined in a longitudinal overlap seam by means of said heat sealing. The tube is filled with the desired filling material and is divided into closed containers by repeated heat sealings of the tube transverse the longitudinal direction of the tube beneath the level of the filling material in the same. The containers are then separated from each other by cuts in the transvers sealings, and the desired geometrical—usually parallelepipedic—configuration is provided by means of an additional forming and heat sealing operation in order to produce the completed packaging containers.
It is important that films of the above-mentioned material, which are to be made weldable, can be brought to fit tightly so that leaking containers with for example milk are avoided. Known package materials with good dimensional rigidity and other necessary mechanical properties for the manufacturing of dimensional stable containers have in practice proved to be difficult to seal by means of heat sealing. The sealing joints have often mechanically been too weak to withstand the outer loads of normal handling of the containers during transport etc., and they have been impaired with local perviousnesses.
One large problem with containers manufactured from a paper or board laminate has always been that they exhibit laminate cut edges exposed to the inside of the container, which contact and easily absorb the liquid content of the container, the desired mechanical rigidity of the laminate and thus the dimensional stability of the container thereby at least locally being impaired or totally lost. The problem has partly been solved by the application of a bridging plastic strip on the above-mentioned overlap seam in the material web formed as a tube during the manufacturing of the laminate to a container. However, in this connection only a protection of the cut edge existing inside a container is obtained.
However, it is likewise important that the remaining cut edges of a container also are protected. The container is often influenced by moisture in the form of water as a liquid or steam, which can be absorbed by the cut edges present on the outside of a finished container. This can for example take place when a cooled container is subjected to the surrounding atmospheric humidity during transport or storage, which humidity is condensed on the container. Also more extreme conditions, such as hot filling as well as preservation by refrigeration and preservation by heat, for example autoclaving, require well protected cut edges on a container.
The purpose of the invention is to provide a container of the kind mentioned by way of introduction, which allows for the elimination of the above-mentioned draw-backs.
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Kjelgaard Tom
Lindsjo Ulf
Nilsson Birger
Cano Milton
James Ray & Associates
Madsen Robert
Tetra Laval Holdings & Finance SA
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