Abstract:
A flexible laminated packaging material ( 100 ) comprises a plurality of layers, at least two of which are bonded together by a layer of adhesive ( 108 ). A first layer ( 113 ) comprises a continuous metallic foil ( 110 ) and a second layer ( 111 ) comprises a continuous web of material incorporating or coated with a laser retardant additive ( 106 ). The material may be scored or cut with a laser ( 114, 118 ) so as to produce offset scores or cuts ( 122, 124 ) wherein a first cut ( 124 ) is made through the first layer ( 113 ), but not past the second layer ( 111 ) and a second cut ( 122 ) is made through the second layer ( 111 ), but not past the first layer ( 113 ). The laser retardant additive ( 106 ) attenuates the power of the laser to help control the depth of the cuts. A method of producing the material by laminating the first and second layers using an adhesive is also disclosed. The method may comprise applying a laser beam to the first web so as to score or cut the first web, but not the second web; and applying a laser beam to the second web so as to score of cut the second web, but not the first web.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/GB2010/051002, which designates the U.S., filed Jun. 17, 2010, which claims the benefit of Great Britain Application No. GB 0911001.6 filed Jun. 25, 2009, the contents of which are incorporated by reference herein. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a laminated material, and in particular to a flexible laminated material for use in packaging which incorporates an integrally formed resealable flap. 
     BACKGROUND TO THE INVENTION 
     It is known to package products, including food products, in a wrapper that is fabricated from a substantially gas and moisture impervious material, such as a metal foil, or a plastics material (including a laminate of either or both materials), in order to protect the product. 
     Such known wrappers may be formed from a length of flat, foldable material having an inner surface directed to the product and an outer surface. The outer surface may be printed on or otherwise be provided with information for the consumer. The material is folded about the product and the longitudinal side edges are bonded together to form a longitudinal sealed seam, sometimes referred to as a “fin seal” or “fin seam”. The material extends beyond the ends of the product and opposing edge regions at either end of the wrapper are bonded together to form transverse end seams. The seams may be formed using an adhesive to bond the opposing surfaces of the wrapper or by heating the material under pressure so that the opposing surfaces melt and fuse together to form a welded seam. 
     Packaging of this nature can be produced using a flow-wrap method in which a film of material is supplied in a roll to package a number of products in a substantially continuous process. The material is fed through a machine which folds it about each product in turn so that opposing side edges are brought into contact and bonded together to form the longitudinal seam, which usually extends along a rear face of the product. The material is crimped at either end of the product to form the end seams and the material is cut to separate each package from the remainder of the film. 
       FIG. 1  shows a commonly used laminated film  10  used in a flow-wrap method. The laminated film comprises an outer surface  11  formed of a clear oriented polypropylene (OPP)  12 , to which an image formed from a layer of ink  14  is reverse printed. The reverse printed OPP  12  is adhered, by means of an adhesive  16  to a metallic foil layer  18 —this foil layer providing the material with a reflective metallic coloured finish. The metallic foil layer in turn has been applied to a substrate of white OPP  20  by means of vacuum or vapour deposition. The non-metallic coated surface of the white OPP  20  forms the inner surface  13  of the laminated material. Once formed, the laminated material  10  can be made into the packaging and sealed at the edges with a permanent adhesive. 
     A number of laminated packaging materials incorporating resealable flaps are known in the art. For example, EP1449789 discloses a packaging container comprising a packing film which is formed from a laminated material incorporating perforations or cut lines on the outer and inner surfaces of the laminated film which may be produced by means of mechanical knives or lasers. 
       FIG. 2A  shows a known laminated film  50  which includes a resealable flap, where the outer and inner surfaces (these surfaces being generally denoted  52  &amp;  54  respectively) are cut in an offset manner by means of lasers. Briefly, the laminated film in  FIG. 2A  comprises a layer of white OPP  56 , to which is applied an image formed a layer of ink  58 . Overlaying the layer of ink  58  is a layer of clear varnish  60  to protect the image during handling of the laminated film. To the underside of the white OPP  56 , an upper metallic foil layer  62  has been applied by means of vacuum or vapour deposition. The upper metallic foil layer  62  is adhered to a lower foil layer  64  by means of a layer of resealable adhesive  66 . The lower foil layer has in turn been deposited on a further layer of white OPP  68 . Lasers  70  and  72  located above and below the laminate  50  can make offset score lines in the upper  52  and lower  54  portions of the laminate so that a resealable flap can be produced (as illustrated in  FIG. 2B ). Generally speaking, the foil layers  62  and  64  are intended to be cut and also prevent the lasers from passing any further in the material during the cutting step. However, in practice, each of the foil layers tends to only attenuate the cutting power of the laser and the following foil layer actually stops the laser from penetrating the laminate any further. This is schematically shown in  FIG. 2A  by the path of the laser penetrating the laminate up to the first foil layer it encounters with a solid line and thereafter a dotted line after is has been attenuated and that the second foil layer actually prevents any further penetration.  FIG. 2B  shows the laminate after being cut by the laser and has an upper cut  74  extending from the varnish  60  to the lower metallic foil layer  64  and a lower cut  76  extending from the further layer of white OPP  68  to the upper metallic foil layer  62 . Unfortunately, the laminate material illustrated in  FIGS. 2A and 2B  is quite thick resulting in handling and wrapping problems and having more than one foil layer greatly increases the cost of the material. 
     It is an object of the present invention to overcome one or more problems associated with the prior art laminated materials. It is also an object to produce an inexpensive laminated material having offset cuts above and below the material which can be produced using a laser. A further object of the present invention is to provide a laminated material which can be reverse printed to improve quality of the finished product and overcome the requirement of a surface varnish. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, there is provided a flexible laminated packaging material comprising a plurality of layers, at least two of which are bonded together by a layer of adhesive, a first layer comprising a continuous metallic foil and a second layer comprising a continuous web of material incorporating or coated with a laser retardant additive having laser retarding properties, the material having offset scores or cuts wherein a first score or cut extends through the first layer, but not past the second layer and a second score or cut extends through the second layer, but not past the first layer. 
     The term “retardant additive” should be taken to mean any material which is capable of hindering, attenuating or mitigating the passage of electromagnetic radiation in the spectrum commonly used to by laser (light amplification by stimulated emission of radiation). 
     It is preferred that the laser retardant additive has laser retardant properties which are similar to those of the continuous metallic foil. In certain embodiments, the laser retardant properties may be identical to those of the continuous metallic foil. However, in other embodiments, the laser retardant properties of the additive may not be identical to those of the metallic foil but must affect the passage of the laser to some degree. 
     The laser retardant additive may be disposed uniformly within and/or on the second layer, disposed randomly within and/or on the second layer, or disposed in a pattern within or on the second layer. The laser retardant additive may be disposed in the second layer so as to be positioned substantially in-line with at least one, more preferably both, of the first and second scores or cuts when considered or viewed in cross section through the two layers. 
     The laser retardant additive may comprise an ink. Such an ink may be a metallic ink. If the laser retardant additive is a metallic ink, then it may comprise a dye mixed with metallic particles and/or flakes. The metallic particles or flakes may be evenly dispersed throughout the ink and may take the form of a suspension. It will be apparent that the accumulative effect of a number of metallic particles or flakes may result in a similar laser retardant effect to that of the metallic foil. 
     The ink may comprise a dye mixed with one or more of the following: metallic particles, metallic flakes, silica, ceramic materials, carbon and derivatives thereof. 
     Alternatively, or additionally, the second layer may comprise the, or a, layer of adhesive. The layer of adhesive may comprise a resealable or permanent adhesive or a pattern comprising areas of resealable and permanent adhesive. The layer of adhesive may comprise patterned areas of resealable and permanent adhesive and the laser retardant additive is incorporated or coated in/on the second layer in a position above or beneath the area of resealable adhesive. 
     The material may be scored or cut with a laser so as to produce the offset scores or cuts. 
     The continuous metallic foil may be bonded to or at least partially coating a plastics substrate. Likewise, the second layer may be bonded to or coating a plastics substrate. The second layer may be bonded to or coating a substantially transparent plastics substrate. 
     In an embodiment of the present invention, the material is used as a wrapper for wrapping consumable products. Consumable products may be a confectionery item(s), such a block chocolate. However, it will be apparent that the wrapper could be used for a wide range of products. 
     In a further embodiment, there is provided a method of producing a flexible laminated packaging material comprising a plurality of layers, the method comprising:
         a. providing a first web of material comprising a continuous metallic film;   b. providing a second web of material incorporating or coated with a laser retardant additive which has laser retarding properties; and   c. laminating the webs together using an adhesive so as to form a laminate.       

     It is preferred that the laser retardant additive in the method has laser retardant properties which are similar to those of the continuous metallic foil. In certain embodiments, the laser retardant properties may be identical to those of the continuous metallic foil. However, in other embodiments, the laser retardant properties of the additive may not be identical to those of the metallic foil but must affect the passage of the laser to some degree. 
     The method may be used to produce a flexible laminated packaging material as herein above described. The method may further comprise the steps:
         d. after lamination, applying a laser beam to the first web so as to score or cut the first web, but not the second web; and   e. applying a laser beam to the second web so as to score or cut the second web, but not the first web.       

     The laser beams applied to the first and second webs will preferably produce scores or cuts which are offset with respect to one another, that is to say, when the laminate is viewed in cross-section, the scores or cuts on adjacent webs are not directly in line with one another. 
     The laminate may be used to form a package for a number of different types of product, including block shaped products and loose products. 
     The laminate may be used in a number of standard packaging and wrapping techniques. Preferably, the laminate is used to form a package in a flow-wrap method. 
    
    
     
       DETAILED DESCRIPTION OF THE INVENTION 
       The present invention will now be more particularly described with reference to and as illustrated in the following figures: 
         FIG. 1  shows a cross-sectional view of a prior art laminated film as commonly used for flow-wrapping products, such as chocolate bars; 
         FIG. 2  shows a cross-sectional view of a second prior art laminated film as used for wrapping stacks of tissue paper or trays of biscuits; 
         FIG. 3  shows a cross-sectional view of an embodiment of the present invention where a metallic ink has been employed as a laser retardant material; 
         FIG. 4  shows a cross-sectional view of a second embodiment of the present invention where an adhesive layer incorporates a laser retardant material; 
         FIG. 5  shows a cross sectional view of a third embodiment of the present invention where a metallic ink has been laid onto a substrate along with non-metallic inks; 
         FIG. 6  shows a plan view of a web of laminated material a fourth embodiment of the present invention; 
         FIG. 7  shows a cross-sectional view of the web of laminated material through the dotted line marked X-X as illustrated in  FIG. 6 ; 
         FIG. 8  shows a plan view of a packaged product made using a portion of a web of material as shown in  FIG. 6 ; and 
         FIG. 9  shows a side view of a packaged product as illustrated in  FIG. 8 . 
     
    
    
     With reference to  FIG. 3 , there is shown a laminated material  100  having five layers: a clear OPP layer  102 ; an ink layer  104  (which includes portions of metallic ink  106 ); an adhesive layer  108 ; a metallic foil layer  110 ; and a white OPP layer  112 . The laminated material  100  is produced by bonding together the two separate webs of material by using adhesive. A first web of material  111  is formed by reverse printing the ink  104  which incorporates a number of portions having a metallic ink  106  onto the clear OPP layer  102 . The second web  113  of material is formed by applying a metallic foil layer  110  to the white OPP layer  112  by means of vacuum or vapour deposition (however, the foil layer may simply be a foil which is bonded to the white OPP by means of an adhesive). The two webs  111 , 113  of material are then adhered to one another such that a layer of adhesive  108  binds the ink layer  104  to a position adjacent to and above the metallic foil layer  110 . 
     A laser is used to produce offset scores or cuts in the first and second webs  111 , 113  of material. As can be seen in  FIG. 3 , the first laser  114  is able to penetrate the clear OPP layer and the ink layer  104 . However, the power of the laser  114  is attenuated by a first portion of metallic ink  116  and whilst the path of the laser still continues to some degree through the adhesive layer  108 , it is unable to penetrate the metallic foil layer  110 . The second web  113  of material can be cut by the second laser  118  which is able to penetrate the white OPP layer  112  and whilst the path of the laser is attenuated by the metallic foil layer  110 , it also passes to some extent through the adhesive layer  108  until it reaches a second portion of metallic ink  120 . The offset cuts (denoted  122  and  124 ) formed by the first and second lasers ( 114  and  118 ) do not impair the sealing characteristics of the laminated material, but allows for the first and second webs to be peeled away from one another in the area between the cuts, if the adhesive layer  108  is a peelable and/or re-sealable adhesive. The laminated material  100  can be fed through a flow-wrap machine in order to produce packaging similar to that shown in  FIGS. 8 and 9  (which will be described in more detail later on). 
     The embodiment as shown in  FIG. 4 , is formed in a similar manner as to the laminated material shown in  FIG. 3 . However, rather than the laminated material having an ink layer  104  having portions of metallic ink, a laser-retardant material is placed within the adhesive layer. Similar layers in  FIG. 3  will be denoted with the same reference numeral prime (‘) for  FIG. 4 . The laminated material  150  is formed having a clear OPP layer  102 ′, and ink layer  104 ′, an adhesive layer  108 ′, a metallic foil layer  110 ′ and a white OPP layer  112 ′. The ink layer  114 ′ does not contain any portions of metallic ink, but rather the adhesive layer  108  has a laser-retardant material  152  disposed therein. The laser-retardant material  152  may be any number of materials known to have laser-attenuating or retarding properties. For example, a laser-retardant material may simply be small metallic particles. 
     As can be seen in  FIG. 4 , a first laser  154  is able to penetrate the clear OPP layer  102 ′, the ink layer  104 ′ and whilst it passes through a laser-retardant particle  156 , the laser is ultimately prevented from passing further than the metallic foil layer  110 ′. A second laser  158  can pass through the white OPP layer  112 ′, and whilst it is attenuated to some degree as it passes through the metallic foil layer  110 ′, it is ultimately prevented from passing further than through the laminated material by means of a metallic particle  160 . 
     The metallic particles  156 ,  160 , may be dispersed randomly or universally throughout the adhesive layer  108 ′. It will be apparent that if desired, using metallic particles which are uniformly dispersed throughout the adhesive layer  108 ′ will allow for the attenuation of the laser to the same degree as to that of the metallic foil layer  110 ′ depending on the concentration and how the metallic particles are dispersed throughout the adhesive layer. Alternatively, the metallic particles may be placed in certain locations around the area intended to be cut by the laser so as to reduce costs of producing the material. 
     With reference to  FIG. 5 , there is shown a further laminated material  200  again having a similar construction as to the materials  100  and  150  shown in  FIGS. 3 and 4 . Similar features in the laminated material  200  to those shown in the laminated materials of  FIG. 3  and  FIG. 4  are denoted with same reference numeral double prime (‘ ’). The laminated material  200  has a plurality of layers consisting of a clear OPP layer  102 ″, an ink layer  104 ″, an adhesive layer  108 ″, a metallic foil layer  110 ″, and a white OPP layer  112 ″. The adhesive layer  108 ″ does not contain any metallic particles as shown in  FIG. 4 , but in common with  FIG. 3 , it has portions of metallic ink  202  located within the ink layer  104 ″. During the print process of the ink layer onto the clear OPP layer  102 ″, metallic ink  202  is layered on the clear OPP layer  102 ″, along with non-metallic coloured ink  204  so as to produce the printed image seen on the outside of the laminated film. As in common with the laminated materials  100  and  150  as shown in  FIG. 3  and  FIG. 4 , the laminated material  200  is formed of two webs  111 ″, 113 ″ of material which are made prior to being bonded together by means of the adhesive layer  110 ″. Also, the adhesive  108 ″ may be a re-sealable adhesive, so that after the offset cuts have been made, the two webs can be pulled apart from one another and resealed if necessary. 
     In  FIG. 5 , a first laser  206  is shown to be able to penetrate the clear OPP layer  102 ″, and is attenuated by a layer of metallic paint  208  and whilst the laser passes through the adhesive layer  108 ″, the metallic layer  110 ″ prevents further penetration. A second layer  210  penetrates the white OPP layer  112 ″, and is attenuated by the metallic foil  110 ″ and passes through the adhesive  108 ″ and ultimately a metallic ink  212  prevents the laser from penetrating further through the laminated material. 
       FIG. 5  illustrates the feature that when applying the image to the clear OPP layer  102 ″, a range of different inks (metallic, non-metallic and coloured) can be used so as to produce differential colour throughout the laminated material so as to provide the colours or images applied to a particular pack. The ease with which a metallic ink can be included in standard apparatus, so as to produce a laser-retardant layer, results in a laminated material which is thin and easy to produce using standard equipment, thus reducing the cost of producing the overall laminated material. 
     With reference to  FIGS. 6 and 7 , there are shown a continuous web of laminated material  300  which, after processing, is cut and run through a flow-wrap machine so as to flow-wrap a particular product, such as a chocolate bar. In common with earlier embodiments, the laminated material generally comprises an upper web  301  and a lower web  305  which are bonded together with adhesive. The continuous web  300  contains a number of “V” cut sections  302  which are areas that are processed by means of a laser prior to the material being used to wrap a given product. The “V” sections shown in  FIG. 6  with a solid line correspond to laser score lines  302  for the upper web  301 , whilst the dotted line corresponds to the lower score lines  303  for the lower web  305 . The web of laminated material  300  is formed of five layers: a clear OPP layer  304 , an ink layer  306  (which includes areas of metallic ink  308 , an adhesive layer  310 , a metallic foil layer  312 , and a white OPP layer  314 . Along either edge of the web, a permanent adhesive  316  is also provided beneath the white OPP layer  314 . 
     As in common with the laminated materials illustrated in  FIGS. 3-5 , the laminated material shown in  FIGS. 6-7  is formed by reverse printing an ink layer  306  to a clear OPP layer  304 . The portions of the ink layer  306  incorporating metallic ink  308  correspond to the edges of the “V” portion  302  in the web of material  300 , as these are the areas which will be subjected to laser scoring. The ink layer  306  will be reverse printed onto the clear OPP layer  102  and forms a first web which is bonded to a white OPP layer  314  to which a metallic foil  312  has been applied. The two webs are adhered to one another by means of the adhesive layer  310 . In order to allow the laser scored “V” to form a re-sealable flap in the packaging when formed, the laminated material is adhered with permanent adhesive  318  throughout the majority of the material  300 . However, the areas between the offset cut (between the “V”) will be formed with a re-sealable adhesive  330 , 332  so that once the offset cuts have been made, a re-sealable flap is formed within the material. The dotted lines shown in  FIG. 7  illustrate the cuts which will be made by the laser and the laser beam will penetrate the material in a similar manner as described with reference to  FIGS. 3-5 . The addition of the permanent adhesive  316  along the edges of the material are used to bind the edges to themselves, when a product is placed centrally in the material during the packaging step so as to farm a thin seal as shown in  FIG. 9 . Transverse bands  322  of permanent adhesive will also form the transverse sealed edges of the package when formed. 
     With reference to  FIGS. 8 and 9 , there is shown a pack  400  which has been formed from a section  320  of the material so as to encase a chocolate bar. The web  300  is formed around the product so as to encase it and the edges are bound to one another by means of the permanent adhesive  316  so as to form the “fin”  410 . Transverse lines of permanent adhesive  322  are brought together so as to form the upper and lower sealing ends for  412 ,  414 , and thus form a sealed pack. When the product is ready to be removed from the pack, the tip  416  of the “V” shaped score line  302  is lifted. The areas of re-sealable adhesive  330 , 332  allow the upper portion of the laminated material to be removed from the lower portion of the laminated material so as to form a flap and allow entry inside the package. If the entire product has not been consumed or removed, the flap can be re-adhered to the lower portion of the material so that the flap from a re-sealable flap. 
     By removing the requirement to have two continuous metallic foil layers in the laminated material, the laminate can be formed much thinner and also at a reduced cost. The laminated material is also compatible with existing machinery, therefore removing the requirement to adapt or modify current flow-wrap machinery. 
     The foregoing embodiments are not intended to limit the scope of protection afforded by the claims, but rather to describe examples how the invention may be put into practice.