PACKAGING FOIL

Abstract: According to the invention, by producing a packaging laminate (5) with an absorbent core layer (2) between an outer foil (1) and an inner foil (3), said latter foil (3) being one through which gas can permeate, in a simple manner there can be produced a packaging foil which can be used for the packaging of especially food products which emit gases and/or vapours, in that these will be absorbed in an effective manner by the core layer (2). The foil (5) can with advantage be produced by extrusion of the core layer (2), and by rolling of the foil layers (1, 3) and the core layer (2) in the formation of the packaging laminate (5). As absorption agent, Ca(OH)2 or CaO can be used for the absorption of CO2 and O2, and moisture.

Description: PACKAGING FOIL Prior art technique The invention concerns a packaging foil in the form of a laminate which comprises an outer layer and a non-gastight inner layer, a method for the production and the use thereof. In the packaging of items which either emit gases and/or vapours, or which must be protected against influences, including particularly influences by moisture, it is known to enclose various chemicals which can absorb the undesired gases and vapours . From the description of US Patent No. 4,366,179 it is known to pack food products in a gastight packaging together with an absorption granulate which is placed in a container or envelope through which gas can permeate, and which is enclosed in the gastight packaging together with the food product . However, the problem with absorption is hereby only partly solved, in that it takes place in an inexpedient manner. There is thus a problem with the extra packaging of the absorbent, which thereafter must be enclosed within the packaging together with the food product. In order to avoid that the absorbent gets mixed with the food product, it must therefore normally be adhered to the packaging, which is both costly and inexpedient. In order to avoid this disadvantage, attempts have been made to form the absorption agent as an evenly-distributed layer on a sheet, and to cover this with a layer provided with almost through-going holes so that the gas can pass for the absorption, cf. JP patent application no. 07031829. This solution is also troublesome, the reason being that the sheet must be placed within the packaging together with the food product. The object of the invention In accordance with the invention, by producing a packaging foil in the form of a laminate, where between the outer layer and the inner layer there is inserted an absorbent layer which consists of a mixture of an absorption agent and a binding agent, in a surprisingly simple manner there is achieved a packaging foil which can function as an ordinary packaging foil and be used in known packaging equipment etc. , but which at the same time is provided with an integrated absorbent which in an effective manner can absorb and protect the packaged item. That the absorption is so effective is due partly to the large surface and herewith the extent of the absorbent, but also that it is active on all sides within the packaging and herewith less sensitive to the orientation and positioning of the packaged item in the packaging. As disclosed in claim 2, to let the absorbent comprise Ca(0H)_ and a binding agent, an effective absorption of C0„ is achieved and herewith also of 0„ . The result is that the foil can be used for the packaging of, for example, ground coffee and similar foodstuffs which give off C0„ , and the taste of which is changed with the presence of 0 . As disclosed in claim 3, to let the absorbent comprise CaO and a binding agent, an effective absorption of moisture and C0„ is achieved in a corresponding manner. As disclosed in claim 4, to let the binding agent consist of a polyethylene with low specific gravity, LD PE, it is possible to effectively mix the granulated components before they are extruded as a layer. As disclosed in claim 5, to produce the packaging laminate by introducing the extruded absorbent layer between an outer layer of foil and an inner layer of foil which are thereafter welded together, a very effective laminate is achieved, the reason being that it provides a high degree of uniformity and herewith effectivity, to which can be ad- ded that it can be used for different forms of packaging, such as bags, sachets, envelopes etc., which can be closed by welding together. Finally, as disclosed in claim 6, it is expedient to use the packaging laminate for the packing of food products which either emit gases and/or vapours or must be protected against the influences hereof. The drawing An example embodiment of the production and the laminate according to the invention will be described in more detail in the following section with reference to the drawing, where fig. 1 shows production dealing with the extrusion of the absorbent and welding together of the layers, and fig. 2 shows a section through the laminate thus produ- ced. Description of the example embodiment Fig. 1 shows schematically an example of how a packaging laminate according to the invention can be produced. The absorbent material, indicated with the figure 2, is shown placed in a silo which constitutes the supply to an extruder 6. The absorbent material for the absorption of C0„ and 0 is preferably Ca(0HX in the form of pulverized hydrated lime. The lime is dried at around 150°C until it has attained a small loss of weight of around 3 percent by weight. The binding agent consists of LD PE which is dried for about 12 hours at a temperature of around 60 °C. Finally, a compatibility agent is added, e.g. in the form of so-called Ken-rich capsules. These three components constitute the absorption agent 2, and they can form a mixture in the ratio of e.g. 40% Ca(0H)„, 59% LD PE and 1% capsules, all given in percent by weight . The extruder 6, which is preferably of the double-worm type with slot nozzles for the extrusion of a broad band, is fed with LD PE and the capsules after these components have been mixed mechanically via a feeder. The Ca(0H)„ is fed to the extruder 6 via a second feeder. The heat zone in the extruder is around 170-190°C, and the melting temperature is around 195°C. After extrusion, the band is air-dried on a conveyor belt. The thickness of the finished layer is around 144 micron, and it has a weight of 2 around 190 g/m , to which is added the binding agent of 2 around 10 g/m . Absorption agents other than Ca(0H)„ can be used, such as CaO. The foil which constitutes the outer layer can be 12 micron PET with an adhesive 4 on the inner side, and possibly with a 12 micron aluminium foil on the outer side. The foil 3, which constitutes the inner layer, can be 25 micron polyethylene or 40 micron MW Bynel . The three layers, i.e. the outer foil 1, the absorbent layer 2 and the inner layer 3, are hereafter laminated in a mangle-like rolling mill with rollers 7 for the formation of the laminate 5, as indicated in fig. 2 which shows a section through the laminate 5. Since gas can permeate through the inner foil 3, a pack- aging made of this laminate 5 enables gases such as C0„ and 0 and vapours to be absorbed by the laminate when a food product is packed in a packaging produced from this laminate. It can be welded together along the sides to form a closed pocket, or it can be used as a cover on a tray or the like. The laminate 5 can be used both in commonly-known packaging machines as well as commonly-known packaging equipment, and thus it can be offered to the producers of food products which require an absorption.

Claims: C L A I M S 1. Packaging foil in the form of a laminate which comprises an outer layer and an inner layer through which gas can permeate, c h a r a c t e r i z e d in that between the two layers (1 and 3) there is inserted an absorbent layer (2) which consists of a mixture of an absorption agent and a binding agent . 2. Packaging foil according to claim 1, c h a r a c t e r i z e d in that the absorbent layer ( 2 ) consists of Ca(0HX and a binding agent. 3. Packaging foil according to claim 1, c h a r a c - t e r i z e d in that the absorbent layer ( 2 ) consists of CaO and a binding agent. 4. Packaging foil according to claims 1-3, c h a r a c t e r i z e d in that the binding agent comprises LD PE, possibly with the addition of a compatibility agent. 5. Method for the production of a packaging foil according to claims 1-4, c h a r a c t e r i z e d in that the absorbent layer ( 2 ) in granulated form is extruded ( 6 ) and introduced between an outer foil ( 1 ) with an adhesive layer (4) and an inner foil (3), after which the layers (1, 2, 3, 4) are laminated (7) in the formation of the finished laminate ( 5 ) . 6. Use of the foil laminate disclosed in claims 1-4 and produced by the method disclosed in claim 5, c h a r a c t e r i z e d in that the laminate ( 5 ) is used especially for the packaging of food products which emit gases and/or vapours which are absorbed by the absorbent layer ( 2 ) . AMENDED CLAIMS [received by the International Bureau on 22 Oune 1998 (22.06.98); original claims 1-6 replaced by new claims 1-3 (1 page)] 1. Packaging foil in the form of a laminate which comprises an outer layer and an inner layer through which gas can permeate, and between the two layers (1 and 3) there is inserted an absorbent layer c h a r a c t e r i z e d in that the absorbent layer (2) consists of Ca(OH)„ and a binding agent. 2. Packaging foil according to claim 1, c h a r a c t e r i z e d in that the absorbent layer ( 2 ) consists of CaO and a binding agent. 3. Use of the foil laminate disclosed in claims 1 and 2, c h a r a c t e r i z e d in that the laminate (5) is used especially for the packaging of food products which emit CO„ and/or vapours which are absorbed by the absorbent layer ( 2 ) .

Inventors: FRIIS JOERGEN, HAASUM IBEN, NIELSEN PER VAEGGEMOSE, FRIIS, JOERGEN, HAASUM, IBEN, NIELSEN, PER, VAEGGEMOSE
Applicants: DANAPAK AS, FRIIS JOERGEN, HAASUM IBEN, NIELSEN PER VAEGGEMOSE, DANAPAK A/S, FRIIS, JOERGEN, HAASUM, IBEN, NIELSEN, PER, VAEGGEMOSE
Application year: 1998
Main classification: B32B27
IPC codes: B32B27