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  Method of providing a package with a barrier and the package thus obtainedUSPTO Application #: 20050208238Title: Method of providing a package with a barrier and the package thus obtained Abstract: A method of providing a package for pourable food products with an oxygen barrier, which method comprises the step of post-applying a liquid oxygen barrier composition comprising a polymer dispersion or solution, as a coating, onto the entire or a selected part of an outside surface of the package. The invention also relates to the package thus produced. (end of abstract)
Agent: Buchanan Ingersoll PC (including Burns, Doane, Swecker & Mathis) - Alexandria, VA, US Inventors: Katarina Flemmer, Mikael Berlin, Stefano Busoli USPTO Applicaton #: 20050208238 - Class: 428034100 (USPTO) Related Patent Categories: Stock Material Or Miscellaneous Articles, Hollow Or Container Type Article (e.g., Tube, Vase, Etc.) The Patent Description & Claims data below is from USPTO Patent Application 20050208238. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a method of providing a package for pourable food products with an oxygen barrier. The invention also relates to the package thus obtained. BACKGROUND OF THE INVENTION [0002] Packages for pourable food products need to have oxygen barrier proper-ties in order for the filled and unopened packages to be able to be stored. The required shelf-life and the degree of oxygen barrier needed depends on the type of food product, the type of packaging material, the type of package, the type of opening on the package etc., and also on aspects such as if the package is aseptic and intended for ambient storage or if is not aseptic and thus intended for chilled storage, e.g. In all cases, some degree of oxygen barrier is needed. [0003] Hitherto, it has been common to provide the packaging material, having a polymeric or fibre based core material e.g., with a barrier layer, already before the package is formed from the packaging material. For example, a packaging material having a fibre based core layer and intended for juice packages, has been laminated with an oxygen barrier layer consisting of aluminium foil. Other packaging laminates, intended for pourable food products less sensitive to oxygen than juice, have been suggested to be provided with an oxygen barrier layer by e.g. extrusion or dispersion coating with a polymer that has oxygen barrier properties, such as e.g. a polymer having functional hydroxyl groups, like polyvinyl alcohol or ethylene vinyl alcohol, optionally mixed with a polymer having functional carboxyl groups, like ethylene acrylic acid copolymers (EAA) or ethylene methacrylic acid copolymers (EMAA).) [0004] In WO 01/17771 and WO 01/17774, showing dispersion coatings coated onto a carrier layer which is subsequently laminated to the core layer of the packaging material, it has also been shown that the oxygen barrier properties of the dispersion coating can be further enhanced by the incorporation of nano-scale clay particles. [0005] In WO 00/40404, there has been described a thermoplastic film, intended for the packaging of food products, such as wrapping the same in a transparent film, but not intended for the production of dimension stable packages for pourable food. The film described in WO 00/40404 has a coating on at least one surface thereof, which coating comprises a polymeric binder and an additive comprising nano-scale particles. It is stated that the nano-scale particles preferably comprise 5 to 20 weight percent of the additive and that the additive comprises 40 to 90 weight percent of the coating. [0006] One problem of providing the packaging material with an oxygen barrier layer before forming the package is that it is hard or even impossible to control the barrier effect on different parts of the package. For example, an increased need for an oxygen barrier at the seals of the package is difficult to achieve without affecting the rest of the package. Also, due to the overlapping nature of conventional seals in a fibre based packaging laminate, a barrier layer in the laminate may not give the desired barrier properties at the overlap of the same. [0007] Moreover, any functional details, such as plastic details or opening devices, pre-applied onto the packaging material or even applied onto the final package, will not exhibit the same oxygen barrier properties as the rest of the material. This is a problem especially in connection with opening devices on aseptic, i.e. sterilised, D packages for oxygen sensitive food products such as fruit or vegetable juices e.g. Some package types may also be built up from different parts of different materials, one example being a package that has side walls and a bottom of a fibre based packaging laminate but a top which is made of plastics (Tetra Top.RTM.). In this case, it may be difficult to achieve the same or essentially the same oxygen barrier properties on all parts of the package. [0008] One type of opening device that poses a special problem in connection with oxygen barrier properties is a pre-applied, direct injection moulded, plastic cap, especially on an aseptic package. By "pre-applied" means that it is applied onto the finished packaging laminate before the packaging laminate is formed into a package, filled with the pourable food product and sealed. If the package is aseptic, the packaging laminate including the pre-applied opening device is sterilised before the form-fill-and-seal operation, usually by peroxide. The aim of achieving such oxygen barrier properties is rendered extra difficult by the fact that any barrier layer created on the cap at its moulding or in connection therewith, must be able to withstand the sterilisation treatment. [0009] Though it might be possible to provide a plastic cap with barrier properties by producing it from a polymer blend, this has a severe impact on mechanical and sealing properties. Another option might be to incorporate an oxygen scavenger in the plastic but this can also influence the mechanical properties and also the oxygen scavenger has to be approved for food packages and it has to be able to function properly under the conditions of the cap. To our knowledge, no known technique exist which is able to give barrier and at the same time acceptable sealing and mechanical properties in the cap. DESCRIPTION OF THE INVENTION [0010] The present invention aims at presenting a method of providing a package for pourable food products with an oxygen barrier, by which method the above problems are overcome or at least decreased. Specifically, the method according to the invention aims at presenting a method by which selected parts of a package can be provided with an oxygen barrier, independent of any oxygen barrier properties on other parts of the package. Moreover, the method according to the invention aims at presenting a method by which details, especially plastic details, such as opening devices, tops etc, on a package can be provided with an oxygen barrier. The invention should be able to provide such barrier properties without influencing the mechanical and sealing properties. According to one aspect of the invention, this is to be achieved also in case the packaging material, including any plastic details, is to be sterilised before forming and filling of the package. [0011] The invention also aims at presenting the package thus obtained. [0012] These and other objectives are achieved by the method according to the invention, as described in the claims. [0013] It has now been found that surprisingly good oxygen barrier properties can be achieved in a package by post-applying a liquid oxygen barrier composition comprising a polymer dispersion or solution, as a coating, onto the entire or a selected part of an outside surface of the package. By "post-applying" is meant that the coating is applied onto the finished package, preferably even after filling and sealing of the same. [0014] According to one aspect of the invention, said oxygen barrier composition is applied by a method in the group that consists of spraying, douching, atomising, brushing and immersion of the selected part of the package. In a commercial application, the coating can be applied by spraying by one, two or more spray nozzles e.g., at rates of thousands of packages per hour, for example 4000-8000 packages per hour. [0015] According to another aspect of the invention, said oxygen barrier composition is applied at a coating thickness of 1-50 .mu.m, preferably 1-40 .mu.m, even more preferred 1-30 .mu.m, even more preferred 1-20 .mu.m, even more preferred 5-20 .mu.m and most preferred 10-15 .mu.m, measured at dry state. [0016] The package is preferably formed mainly of a fibre based packaging laminate but applications are conceivable also in cases where the package is formed mainly of a polymeric packaging material. Also, combinations are conceivable, such as for example a package that has side walls and a bottom of a fibre based packaging laminate but a top that is polymer based (such as Tetra Top.RTM. e.g.) [0017] If only a selected part of the package is coated according to the method according to the invention, this selected part of the package is preferably a part in the group that consists of a seal, an opening device, a plastic detail on the package and a plastic part of the package, such as a plastic top e.g. In an especially preferred embodiment of the invention, the oxygen barrier composition is applied onto the outside of a direct injection moulded opening device (cap), in order to provide the cap with oxygen barrier properties. Here, the outer surface post-applying of the oxygen barrier coating beneficially means that the packaging laminate, including intermittently arranged caps, can be sterilised already before applying the oxygen barrier coating onto the caps, whereby the coating need not be resistant to the sterilising agent. According to this embodiment of the invention, the method includes the steps of: [0018] (a) injection moulding plastic opening devices in opening holes on a packaging material web, [0019] (b) forming the packaging material web to a tube while sealing its longitudinal edges to each other and filling the tube with a pourable food product, [0020] (c) intermittently sealing the tube in transversal seals and cutting the tube in the transversal seals to form cushions, [0021] (d) folding the cushions to form dimension stabile packages, each having one plastic opening device, where after said liquid oxygen barrier composition is applied onto the outside of said opening devices in a step (e). Continue reading... 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