Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1998-04-27
2000-04-04
Stemmer, Daniel
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
15624424, B32B 3126
Patent
active
06045654&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for fastening two adjacent layers to each other in a package material, more specifically for fastening a barrier layer to an adjacent laminate layer in a package material.
A laminated package material in the form of a packaging laminate having a base layer of paper or cardboard, which gives the container strength and dimensional stability has for a long time been used within the packaging industry. The base layer in these known packaging laminates is often very thick and thereby confers the container good mechanical strength and dimensional stability. Outer thermoplastic layers on the other hand result in a liquid impervious container while they at the same time make it possible to convert the package material to containers by means of what is called heat sealing, in which thermoplastic layers facing each other while being supplied with heat and pressure are brought to surface fusion with each other in order to form mechanically strong and liquid impervious sealing joints.
A packaging laminate comprising only a base layer and polyethylene has good mechanical properties and good sealing properties against moisture and liquid but practically completely lacks barrier properties. In this connection a barrier layer means a laminate layer with good barrier properties against light, gases and/or flavouring agents.
In order to be able to use the packaging laminate in containers for e.g. light sensitive products the laminate thus has to be supplemented with at least one additional layer of a material with light barrier properties. In containers for such liquid foods as juice, wine, cooking oil, etc., a package material having good gas barrier properties is required. An often used gas barrier layer is a thin foil of aluminium which is applied against one side of the base layer. An Al foil is by itself completely oxygen im-permeable and has also other valuable barrier properties valuable for the filled product, e.g. light impermeability, while at the same time it is possible to accomplish im-pervious and mechanically strong splicings of the material by inductive heating during the conversion of the material to containers. Furthermore, an Al foil applied against the inside of the laminate must be covered with one or several plastic layers, usually polyethylene, in order to prevent contact between the aluminium foil and the later on filled food. Often the barrier layer cannot be bound directly to the base layer, but instead a good adhesion requires one or several intermediate binding layers.
An Al foil is not only an expensive material, but known package materials containing aluminium have several serious drawbacks. These depend to a large extent, and in certain cases completely, on the fact that the Al foil used as a barrier layer because of its low ability to stretch often ruptures in especially vulnerable areas of the material during the manufacturing of containers and in that way impairs the impermeability of the completed container. These known package materials also have drawbacks caused by the soaking paper or cardboard layers which rapidly loose their mechanical strength properties and make the container flabby and cumbersome when it is exposed to liquid or moisture. Furthermore, the paper or cardboard layer must be made relatively thick in order to give the container a necessary dimensional rigidity, which contributes to increasing the material load and thus the risk of crack formation in the Al foil during the manufacturing of containers.
When containers of the kind described above are manufactured the package material is often subjected to stresses which become especially great when the material is folded, since a folding results in tensions in the material due to the comparatively large thickness of the base layer. If the material in addition comprises a barrier layer which compared with plastic coatings has a very small tensile strength, the material then easily can rupture at the material folding.
The problem becomes aggravated when the material has to be folded a
REFERENCES:
patent: 3648834 (1972-03-01), Gifford
patent: 3762598 (1973-10-01), Gayner
patent: 4308084 (1981-12-01), Ohtusuki
patent: 5296070 (1994-03-01), Take
patent: 5314561 (1994-05-01), Komiya
patent: 5759422 (1998-06-01), Schmelzer
Kjelgaard Tom
Magnusson Katarina
Ringdahl Ulf
Stemmer Daniel
Tetra Laval Holdings & Finance S.A.
LandOfFree
Method for producing a packaging laminate with barrier propertie does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing a packaging laminate with barrier propertie, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing a packaging laminate with barrier propertie will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-361392