A Multi-Layer Laminate

FIELD OF THE INVENTION

[001] The invention relates to a multilayer laminate and a process for production thereof, more particularly to a multi-layer laminate for packaging applications, especially for solid consumables.

DEFINITIONS

[002] The technical terms used in accordance with the present disclosure include but are not limited to the following:

CONSUMABLE: Any solid edible item, preferably small edibles such as candies, chewing gums, gummy strips, mouth freshener strips, butter cubes, soup cubes, eclairs, margarine packs, cheese cubes, cheese single slices, biscuit packs etc.

BACKGROUND OF THE INVENTION

[003] Integrity of packaging and extended shelf life are vital factors while packaging of edible items or consumables. For small sized solid consumables, the packaging laminates are designed such that the printing, barrier & sealant layers are of a minimum thickness as the focus is always on achieving required functionality & machine ability while keeping the cost factor to a minimum. [004] Packaging of such items preferably includes various kinds of heat seal coatings as the sealant layer instead of using blown polyethylene (PE) films, extrusion coating of PE or polypropylene (PP) resins. Thus, heat seal coatings are the preferred options when the product size is small and the pack weight is minimal.

[005] Products like soup cubes are challenging from a packaging perspective since their product barrier requirement is very high & they are packed on high speed packaging machines. The individual sizes of such packages are small and the weight is typically between 10-30 gms/piece. This means that while they need high barrier substrates like aluminum foil or metallized BOPP, metallized polyester films as one of the components of the laminate, they can work with heat seal coatings as sealant medium as the unit weight/pack is low.

[006] These small sized solid consumables are typically packaged in multilayer laminate using a lap seal configuration, where the heat seal layer on the inner surface of the laminate seals with a patterned seal layer on the outer surface of the laminate. The patterned heat seal layer is most commonly achieved using a heat seal coating. The lap seal is achieved by means of folding the laminates and overlapping and sealing in certain pre-determined areas by heat seal. These laminates generally also comprise a protective over print varnish coating on top of the ink layer, which is normally a heat resistant layer and is used to avoid the ink rubbing off (also called scuffing) when the heat seal jaws of packing machine come in contact with the ink. The overprint varnish coating is above the ink layer and below the patterned seal layer.

[007] The problems associated with the above packaging laminates are that both the patterned heat sealing layer on top of the protective over print varnish as well as the overprint varnish itself, needs to be transparent in order to avoid interference with the printed artwork underneath. At the same time, both these need to be positioned exactly at the areas intended, which is challenging to achieve during high speed manufacturing operation. Moreover, even a slight misplacement of the patterned heat-sealing layer from its intended position (called misregistration) leads to higher scrap rates and thus wastage during manufacturing operation. Further, if the heat seal layer is misregistered, then during the packaging operation the wrappers do not seal at all or seal partially leading to loss of time, waste etc. In extreme cases, if the unsealed /partially sealed product is not caught during quality control/quality assurance process and gets into the market, it can lead to a food safety issue for the consumer. Also, applying the heat seal layer coating on the inner side of the base film (typically a polyolefin film) is an additional process step which is expensive and time consuming.

[008] In view of the above, there is a need for packaging laminates that overcome the aforementioned disadvantages.

SUMMARY OF THE INVENTION

[009] In one aspect, the invention provides a multi-layer laminate (100) for packaging a consumable, the multi-layer laminate comprising of: a base layer 102 having an inner surface and an outer surface, the base layer is an oriented polyolefin film; a co-polymer layer 101 applied on the inner surface of the base layer; a layer 103 having metallic properties laminated to the outer surface of the base layer; and a protective coating 105 on the layer 103, the protective coating 105 selected from nitro cellulose, poly urethane and/or poly amide family of chemicals, the protective coating (105) on the layer 103 seals with the co-polymer layer 101 for enclosing the consumable.

BRIEF DESCRIPTION OF THE DRAWINGS

[010] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[Oi l] Figure 1 shows a cross sectional view of the multi-layer laminate in accordance with an embodiment of the invention. DESCRIPTION OF THE INVENTION

[012] The present invention is directed towards a laminate for packaging applications, especially for packaging of small, solid consumables, including, but not limited to, candies, chewing gums, gummy strips, mouth freshener strips, butter cubes, soup cubes, eclairs, margarine packs, cheese cubes, cheese single slices, biscuit packs etc. which require lap seal packaging.

[013] In one aspect, the present invention provides a multi-layer laminate as shown in Fig 1 comprising a laminate (100) comprising of a base layer (102) of an OPOF (oriented polyolefin film). The base layer has an inner and outer surface. The inner surface of the base layer has a copolymer layer (101) thereon. The outer surface of the base layer has a layer 103 having metallic properties laminated thereon. The layer 103 is optionally surface printed and has a layer of protective coating 105 applied on the printed side. The protective coating 105 is selected from nitro cellulose, poly urethane and/or poly amide family of chemicals. As shown, the laminate has a face A and a face B. The face A has a co-polymer coating 101 and the face B comprises the protective coating layer 105. The protective coating 105 on the layer 103 forms a seal with the copolymer layer 101 for enclosing the consumable. That is, the face A is capable of sealing with face B to form a packaging.

[014] In an embodiment of the invention, the copolymer layer is an ethylene- vinyl-acetate (EVA) layer or a terpolymer layer. The terpolymer is selected from ethylene, propylene, alpha olefins etc, more specifically from either Ethylene propylene alpha olefins, Ethylene - propylene - diene monomer, Ethylene- butyl acrylate- maleic anhydride terpolymer, Ethylene - vinyl acetate- maleic anhydride terpolymer etc.

[015] In another embodiment of the invention, the layer having metallic properties can be selected from a metal layer or a metallized layer. The metallized layer is selected from, but not limited to, metallised films, vacuum metallised polyethylene terephthalate (Metpet), vacuum metallised bi- axially oriented polypropylene film (metbopp), vacuum metallised nylon, vacuum metallised CPP. The metal layer is an aluminum foil.

[016] The protective covering provides heat resistance during packaging while at the same time avoiding scuffing of the print/ink layer. Further, the protective covering acts as a sealant and accordingly, a packaging for enclosing the consumable can be formed with a transverse/ longitudinal lap seal where opposing faces of the film are sealed by overlapping of the face having EVA/terpolymer (Face A) with face having protective coating (Face B)

[017] Furthermore, there may be additional barrier layers sandwiched / laminated between the OPOF film base layer and the metalized/metallic barrier layer as per the product barrier requirement. The aluminum foil or metallized barrier layer may be replaced with any other layer as per the product requirement. Similarly, the EVA / terpolymer layer may also formulated with slip and anti-blocking additives for smooth machineability / runability on packaging lines.

[018] The invention also relates to a process for forming a laminate. The process comprises the steps of providing an OPOF (oriented polyolefin) film containing a layer of copolymer co-extruded on its inner surface; laminating an layer having metallic properties to the outer surface of the OPOF film; optionally printing on top surface of the layer having metallic properties followed by applying a protective coating thereon.

[019] In another embodiment, the coating of co-polymer layer on the oriented polyolefin (OPOF) film may be achieved by extrusion coating of the co-polymer on the base polyolefin film in an separate offline process. Alternatively, the copolymer can also be ‘’wet coated” like a lacquer using a water / solvent based dispersion medium on conversion equipment.

[020] As discussed hereinbefore, the multi-layer laminate of the present invention is used for packaging small consumables, such as soup cubes, wherein a packaging can be formed with a lap seal at a seal initiation temperature starting from 85°C. The effective sealing of the copolymer with the protective coating layer provides good seal ability resulting in faster machine speed/processing leading to higher production.

EXAMPLES

[021] The following experimental examples are illustrative of the invention but not limitative of the scope thereof:

Example 1

[022] A laminate was prepared in accordance with an embodiment of the invention comprising the following layers:

A nitrocellulose polyurethane Overprint Varnish layer of 1.5Gms; an Ink layer of 2.5Gsm; a Foil wash 0.5Gsm; an aluminum foil of 7p;

Adhesive layer of 3Gsm; and

37p cavitated BOPP with EVA Coating.

[023] The Lap seal strength of said multi-layer laminate was tested at varying temperatures and pressures and compared with that of a conventional laminate. The conventional laminate comprised of a BOPP film with a heat seal coating on the inner surface and the outer surface being laminated with an aluminum foil. The aluminum foil has an print/ink layer on the top surface with the print/ink layer being covered with an overprint varnish and a patterned heat sealant applied on the overprint varnish.

[024] The results are shown in table below:

[025] The table compares the heat seal strength of the conventional lap seal packaging laminate with the multi-layer laminate of the present invention at various seal temperatures and seal pressures. From the table, it is evident that even at very low temperature of 85°C and bare minimum pressure, sealing is initiated and the seal strength is greatly enhanced in the multi-layer laminate of the present invention as compared to the conventional packaging laminates.

[026] Advantageously, the present invention provides a multi-layer laminate with high sealability, while avoiding the application of patterned heat sealing medium as well as overprint varnish on the film, thus overcoming the misregistration and wastage problems and making the manufacturing process simpler Further, the sealing temperature of these laminates is such that it falls within the sealing temperature band of OPOF films without adversely affecting them.

[027] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.