Patent Publication Number: US-11396414-B2

Title: Closure member for a food container

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Phase of International Application PCT/IB2018/059028 filed Nov. 16, 2018 which designated the U.S. 
     This application claims priority to Italian Patent Application No. 102017000133121 filed Nov. 21, 2017, which application is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a closure member for a food container. 
     In particular, the closure member which is the object of the present invention is mainly used in the production of repositionable closure films, typically used for closing food trays. 
     Therefore, the main field of application of the present invention is that of food packaging, but the same type of laminate could also be applied in other sectors in which it is necessary to provide a particularly effective and reduced cost reclosable film. 
     With specific reference to the food industry, in the prior art multilayer closure films are commonly used, which have a base layer, usually at least partly made of welding material, on which a (printed) ribbon is positioned. 
     To guarantee the sealing and the repositioning of the printed ribbon, a “repositionable” adhesive is interposed between the two layers, which is able to guarantee a predetermined number of openings/closures of the container without losing the tightness of the coupling. 
     One of the problems that have always been associated to these laminates is related to the difficulty of opening them, consider, e.g., the trays used to close fresh products or sausages, which, most often, require a great user effort and, sometimes, it is necessary to damage the film to allow access to the compartment of the container (with irretrievable loss of the seal). 
     In order to overcome this problem, the prior art proposes a solution in which, during the repositionable adhesive distribution, some longitudinal film strips (i.e. extending in the film winding direction) are left without adhesive; using these areas as a reference, the geometry of the covering will then be die cut, making sure that they fall close to the notches suitable to allow (facilitate) the lifting of the printed layer. 
     However, such embodiment, while being efficient in terms of easy opening, carries several drawbacks both in terms of production flexibility and visibility of the warranty seal (i.e., anti-tampering). 
     In fact, the need to make long adhesive-free strips on all the length of the film, besides leading to the production of high material wastage, makes the production of the laminate advantageous only for large production sizes and lots having dimensions not always consistent with the customer needs. 
     BRIEF SUMMARY OF THE INVENTION 
     Object of the present invention is to provide a closure member for a food container which overcomes the drawbacks of the prior art mentioned above. 
     In particular, the object of the present invention is to provide a closure member for a food container which facilitates the displaying, by a user, of any possible tampering. 
     Said objects are achieved by a reclosable closure member for a food container having the features of one or more of the following claims. 
     The closure member comprises a multilayer laminate having a first layer of material at least partly light permeable, a second layer of plastic material and a third layer of repositionable adhesive material interposed between said first and said second layer. 
     According to an aspect of the present invention, the laminate comprises a plurality of anti-adhesive strips sequentially arranged and spaced apart from each other along said main direction, wherein each anti-adhesive strip is interposed between the first layer and the second layer. 
     Advantageously, the anti-adhesive strips can be placed locally, preferably in register, which gives the manufacturer maximum operating versatility. 
     It should be noted that, the second layer has a predetermined graphic pattern printed or formed on at least one of its faces. 
     The closure member therefore comprises the laminate described above, suitably die cut so as to be peripherally delimited by a peripheral edge having a predetermined conformation suitable for covering an opening of a corresponding container and defining at least one hand gripping portion for a user. 
     It should be noted that at least one of said plurality of anti-adhesive strips is placed near said hand gripping portion. 
     Then, the closure member has at least one inner weakening line, far from the peripheral edge, obtained on said second layer and extending according to a predetermined defining geometry, in use, an access gap to the container and at least one outer weakening line, proximal to the peripheral edge, obtained on said second layer and placed at said anti-adhesive strip 
     In other words, the anti-adhesive strip is placed astride the outer weakening line. 
     Advantageously, in this way it is possible to provide, in register, an anti-adhesive strip capable of giving a greater tolerance to the production process of the closure member, effectively guaranteeing the correct opening of the container even if the outer weakening line is not perfectly located with respect to the strip welded to the edge of the container. 
     Preferably, moreover, the predetermined graphic pattern of the second layer extends at least partly astride said inner weakening line to define a tamper-evident tab. 
     Advantageously, in this way it is easy to introduce a particularly reliable “tamper evidence”, required by most manufacturers nowadays. 
     Furthermore, the aforementioned objects are achieved by a method for producing a multilayer laminate for food packaging as well as a method for producing a closure member for a food container. 
     Preferably, such method provides for providing a first film of plastic material at least partially light permeable having at least one adhesive face covered by a layer of repositionable adhesive material. 
     A second film of plastic material having a first and a second face and having a graphic pattern printed on said first or said second face is also provided. 
     The first and/or the second film are advanced along respective main directions. 
     According to an aspect of the invention, a discrete application of a plurality of anti-adhesive strips is performed on said first face of the second film or on said adhesive face of the first film. 
     Preferably, the strips are sequentially arranged and spaced apart along the respective main direction. 
     This application step is carried out upstream to the coupling between the adhesive face of the first film and the first face of the second film to realize said multilayer laminate. 
     Advantageously, therefore, the anti-adhesive strips are applied locally on a surface completely covered with adhesive, with great benefit for the operational flexibility and maximizing the “useful” fraction of the film (i.e. limiting the wastages). 
     Once this laminate has been realised, it is then possible to realise the closure member for a food container. 
     Such method envisages to provide the laminate previously described, which is the object of the present invention, and to realise:
         at least one inner weakening line formed on said second layer and extending according to a predetermined geometry; and   at least one outer weakening line formed on said second layer and placed at said anti-adhesive strip.       

     Furthermore, in order to adapt the closure member to the container geometry, a laminate notch is provided according to a perimeter having a peripheral edge surrounding said weakening lines and provided with at least one hand gripping portion for a user, wherein at least at said hand gripping portion the inner weakening line is far from the peripheral edge with respect to said outer weakening line. 
     Advantageously, in this way it is possible to easily and quickly produce closure members of any geometry and provided with a reliable opening (or peeling) system. 
     Further innovative aspects of the present invention, alternative or complementary to each other, can be found among the following. 
     The anti-adhesive strips are preferably positioned between the second and third layer. Therefore, preferably, each anti-adhesive strip is applied to the second layer and subsequently applied/coupled to the third layer (in turn preferably already coupled to the first). 
     Preferably, once coupled, the second layer of the laminate has a first face covered by said repositionable adhesive and a second face, opposite the first one, having said printed graphic pattern. 
     The anti-adhesive strips are preferably printed on the first face of the second ribbon, i.e., on the first face of the second film. 
     More preferably, the anti-adhesive strips are printed or applied in register on such face, so as to maximize the operational flexibility of the manufacturer. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Further technical features and the related benefits of the invention will become more apparent from the following exemplary, and therefore non-limiting description of a preferred, and therefore not exclusive embodiment of multilayer laminate for food packaging and a method for the realisation of said laminate as shown in the attached drawings, wherein: 
         FIG. 1  shows a schematic view of a plant implementing the method for the realisation of a multilayer laminate for food packaging; 
         FIGS. 2-5   a  schematically show a succession of steps of the method of  FIG. 1  with related details of the laminate. 
         FIG. 6  schematically shows a sectional view of a closure member for a food container according to the present invention in a first condition of use; 
         FIG. 7  shows a perspective view of a closure member for a food container according to the present invention in a second condition of use; and 
         FIG. 7A  shows an enlarged detail of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the appended figures, number  1  indicates a multilayer laminate for food packaging according to the present invention. 
     Such laminate  1  is as said “multilayer”, i.e., it is constituted by a plurality of individual layers suitably coupled and superimposed on each other in order to define an individual windable material or film. 
     It should be noted, in fact, that the laminate  1  is a windable material extending along its own main direction “A”, or wrapping direction. 
     Preferably, furthermore, the laminate  1  is stored in film coils B wrapped around a central axis perpendicular to the main direction “A”. 
     Such laminate  1  comprises a first layer  2  made of a material at least partially light permeable; said first layer  2  is, in use, a top layer and has at least one portion light permeable (i.e. transparent or translucent) which allows the displaying of at least one successive layer. 
     The first layer  2  is preferably made of PET or alternatively, e.g., of polypropylene or polyamide. 
     Preferably, moreover, the first layer has a thickness ranging between 5 and 80 μm, more preferably between 10 and 50 μm. 
     In this regard, the laminate comprises in fact a second layer  3  of plastic material. 
     Preferably, such second layer  3  has a predetermined graphic pattern “G” printed or formed on at least one of its faces  3   b.    
     In the preferred embodiment, the second layer  3  has a first  3   a  and a second face  3   b;  the graphic pattern “G” being realised on said second face  3   b.  Preferably, the graphic pattern is printed on the second face, e.g., with flexography, rotogravure, offset, screen printing, or digital printing. 
     Note that the graphic pattern “G” can be any graphic, ornamental or functional representation. 
     “Functional” graphic representation refers herein to the “register” or reference nicks which are also realised on completely transparent laminates to allow subsequent die cutting or carving processing. 
     Therefore, it is not necessary that on the second layer  3  there are invasive or ornamental representations, but it is sufficient that on one of its faces the nicks or references useful for subsequent processing are reported to define them as a “graphic pattern” according to the present description. 
     In the preferred embodiments, the second layer  3  is made, e.g., of polyester, polyamide, polypropylene or even aluminum. 
     Preferably, such second layer  3  has a thickness ranging between 1 and 50 μm, more preferably between 5 and 30 μm. 
     Preferably, moreover, it is provided the presence of a third layer  4  made of a repositionable adhesive material interposed between the first layer  2  and the second layer  3 . 
     In particular, the third layer  4  is coupled to the first face  3   a  of the second layer  3 . 
     Such third layer  4  is therefore interposed between the first layer  2  and the first face  3   a  of the second layer  3 . 
     The second face  3   b  of the second layer  3 , having the graphic pattern “G”, is facing away from the first layer  2 . 
     In other words, the first face  3   a  of the second layer  3  is covered by said repositionable adhesive (i.e. coupled to the third layer  4 ), while the second face  3   b  has the graphic pattern “G”. 
     Advantageously, in this way when the first and the second layers are separated (e.g., during the opening of a container), there is no risk that the adhesive “tears” or damages the graphic pattern “G”. 
     It should be noted that “repositionable adhesive material” refers to an adhesive which, by its own characteristics or by interaction with the materials of the other two layers, allows to couple together and uncouple the two layers from each other for a predetermined number of times while maintaining its “binding” (i.e. not dry) capacity. Substances of this type are typically used in the realisation of adhesive/self-adhesive ribbons. 
     For example, the repositionable adhesive material could be acrylic-based glue. 
     According to an aspect of the present invention, the laminate  1  comprises a plurality of anti-adhesive strips  5  sequentially arranged and mutually spaced apart along the main direction “A”. 
     It should be noted that the anti-adhesive strips  5  can also be arranged on several transversal (to the main direction “A”) rows spaced apart from each other. 
     Each strip, in any case, is interposed between the first  2  and the second layer  3 . 
     Preferably, the anti-adhesive strips  5  are positioned between the second  3  and the third layer  4  (i.e. between the adhesive material and the “inner” in use layer of the laminate). 
     It should be noted that “anti-adhesive strip” refers herein to a localized portion of anti-adhesive material which is applied above the second layer  3  (or on the first layer  2 ), without necessarily conferring an elongated or oblong conformation to the same (however preferable). 
     Preferably, the anti-adhesive strips  5  are at least partly defined by a flap of anti-adhesive resin locally distributed on the second layer  3 . 
     For example, with “anti-adhesive resin” a silicone trace or non-stick resin is identified. 
     In a further alternative, however, the anti-adhesive strip could also be defined by a tape of non-stick material deposited on the second layer  3 . 
     Preferably, the anti-adhesive strips  5  (or rows of strips  5 ) are spaced apart, along the main direction “A”, with a constant pitch “p”. 
     In the preferred embodiment, the laminate  1  comprises a further layer  6  made of welding material coupled to the second layer  3  on the opposite side with respect to the first layer  2 . 
     In other words, the further layer  6  of welding material is coupled with the second face  3   b  of the second layer  3  (i.e., the one bearing the graphic pattern “G”). 
     The further layer  6  of welding material is preferably made of polythene, polypropylene, polyester, aluminum, paper or a material coated with heat-sealing lacquers. 
     The function of such further layer  6  is to allow the adhesion/coupling of the laminate with a containment body (e.g., a tray) by heat-sealing. 
     It should be noted that, in some embodiments, the second layer  3  and the further layer  6  are integrated into a single layer of material. 
     Thanks to the laminate  1  described hitherto, it is possible to realise a closure member for a food container which, in the figures, is indicated by the number  100  ( FIGS. 6 and 7 ). 
     Such laminate is in fact notched so as to be peripherally delimited exactly by one of its peripheral edge  100   a  having a predetermined conformation adapted to occlude an opening  201  of a corresponding container  200 . 
     The conformation of the closure member  100  is therefore defined by the die cutting of the laminate and is variable according to the conformation of the container. 
     In any case, the peripheral edge  100   a  is shaped so as to define at least one hand gripping portion  101  for a user. Typically, the hand gripping portion  101  is defined by a tab laterally projecting with respect to the edge of the container, but it can also be realised in another way. 
     At least one of said plurality of anti-adhesive strips  5  is placed near the hand gripping portion  101 . 
     According to an aspect of the invention, the laminate  1  is then notched with a plurality of weakening lines suitable to allow the opening of the container and, preferably, to allow the repositioning thereof. 
     Such weakening lines are in fact non-through notches which pass through the second layer  3  (and the further layer  6 , when present) until reaching the repositionable adhesive layer  4 , without engraving the first layer  2 . 
     With such a conformation, therefore, the weakening lines favour the delamination between the first  2  and the second layer  3  when the user “pulls” the closure member at the hand gripping portion  101 . 
     In particular, at least one inner weakening line  102 , far from the peripheral edge  100   a,  formed on the second layer  3  and extending according to a predetermined geometry defining, in use, an access gap to the container is then provided. 
     Moreover, according to an aspect of the invention, there is also an outer weakening line  103 , proximal to the peripheral edge  100   a,  obtained on said second layer  3  and placed at said anti-adhesive strip  5 . 
     More precisely, the anti-adhesive strip  5  extends astride the outer weakening line  103 . 
     Advantageously, in this way the anti-adhesive strip  5  defines a tolerance buffer for delamination, favouring the separation between the first  2  and the second layer  3  even in the case of not perfect positioning between the portion of a closure member welded to the container (second layer  3  or further welding layer  6 ) and the outer weakening line  103 . 
     Preferably, moreover, the predetermined graphic pattern “G” of the second layer  3  extends at least partly astride the inner weakening line  102  to define a tamper-evident tab “TE” (see  FIG. 7 ). 
     Therefore, since the graphic pattern “G” is separated into two distinct parts by the inner weakening line  102  at the opening of the closure member  100 , it is not possible to completely recompose it at the reclosing of the same. 
     In this way, without the need to provide external elements, the tamper-evident tab is an integral part of the closure member  100  and of the laminate  1  already during production step. 
     Preferably, the inner weakening line  102  defines a projecting tab away from said hand gripping portion  101  ( FIG. 7 ). 
     A further object of the present invention is, as mentioned, a method for the realisation of a laminate for food packaging, preferably but not exclusively of the type described hitherto. 
     The method envisages to provide, preferably in a coil form, a first film  10  made of plastic material at least partially light permeable having at least one adhesive face  10   a.    
     Therefore, said first film  10  comprises a ribbon  20  made of plastic material having at least one face  20   a  covered by a layer  40  made of repositionable adhesive material. 
     It should be noted that the first film  10  could be defined by a self-adhesive ribbon already provided and having the layer  40  made of repositionable adhesive material or, in some other embodiments, it could be realised in-line. 
     In such latter embodiments, the ribbon  20  made of plastic material at least partially light permeable is provided and subsequently, on its face  20   a,  the layer  40  made of adhesive material is applied. 
     Once the ribbon  20  and the layer  40  have been coupled to realise the first film  10 , they respectively define the first  2  and the third layer  4  of the laminate  1  described above. 
     Therefore, the ribbon  20  is preferably made of PET or alternatively, e.g., of polypropylene or polyamide. Preferably, moreover, such ribbon  20  has a thickness ranging between 5 and 80 μm, more preferably between 10 and 50 μm. 
     Likewise, the layer  40  of repositionable adhesive material could be, similarly to what stated above, acrylic-based glue. 
     Returning to the method, it then envisages to provide a second film  30  of plastic material having a first face  30   a  and a second face  30   b.    
     Preferably, the second film  30  has a graphic pattern “G” on at least one of the faces (the first  30   a  or the second  30   b ). 
     In the preferred embodiment, the graphic pattern “G” is coupled to the second face  30   b.    
     Therefore, such second film  30  defines the second layer  3  of the laminate  1  previously described. 
     It should be noted that, similarly to the first film  10 , the second film  30  could also be provided already printed or, alternatively, realised in-line. 
     In such second alternative, the method would envisage to provide a ribbon of plastic or polymeric material advancing it inside a printing device (not shown) to realise the second film  30 . 
     Once the first  10  and the second film  30  have been provided, these films are advanced along respective main directions “A”. 
     The first  10  and the second film  30  are then advanced until overlapping each other so that they are facing each other and substantially parallel. 
     During the advancement of the first  20  or second film  30 , a plurality of anti-adhesive strips  5  is applied in a discrete (non-continuous) manner on the first face  30   a  of the second film  30  or on the adhesive face  10   a  of the first film  10 . 
     With regard to the definition of “anti-adhesive strip”, please refer to what previously illustrated above in this regard. 
     Preferably, the anti-adhesive strips  5  are applied on the first face  30   a  of the second film  30 . 
     The step of applying the anti-adhesive strips  5  preferably provides for arranging such strips  5  arranged sequentially and spaced apart along the respective main direction “A”. 
     In other words, the strips  5  are applied “in pitch” so that each strip is spaced apart from the next one along the advancement direction of the film  10 ,  30 . 
     Preferably, the anti-adhesive strips  5  (or the rows/arrays of strips) are deposited or applied on the respective face  10   a,    30   a,  spacing them with a constant pitch “p”. 
     It should be noted that the strips  5  could also be applied in rows or arrays transverse to the advancement direction of the film  10 ,  30 ; in this case each strip of a row would be spaced, along the advancement direction, by the corresponding strip  5  of the next row or array. 
     The application of each strip  5  preferably provides for printing the anti-adhesive strip  5  on the first face  30   a  of the second film  30 . 
     The strips are therefore applied “in register”, being able to simply modify the shape, the pitch and the position modifying the conformation or the positioning of the printing or applicator plates. 
     Once the strips  5  have been applied, the method involves coupling the first  10  and the second film  30  together. 
     In particular, the adhesive face  10   a  of the first film  10  is superimposed and coupled with the first face  30   a  of the second film  30 . 
     Preferably, such films are mutually coupled by means of a calendar or the like, in order to realise a multilayer laminate, preferably corresponding to the laminate  1  previously described and which is also an object of the present invention. 
     In this regard, preferably the method provides for a further step sequence. 
     Such further sequence envisages to provide a step of a further film  60  of welding material and coupling such further film  60  with the second face  30   b  of the second film  30 . 
     It should be noted that this step could be performed in-line, either before or after the application of strips  5 , or off-line. 
     If it is performed off-line, the coupling between the further film  60  and the second film  30  could take place upstream of the steps described hitherto or downstream. 
     In the first case (upstream), it would be possible to realise a multilayer film comprising the second film  30  and the further film  60  which would be subsequently coupled with the strips  5  and the first film  10 . 
     In the second case (downstream), the further film  60  could be coupled to the already realised laminate (defined by the first film  10 , by the second film  30  and by the anti-adhesive strips  5 ). 
     The laminate  1  thus produced is then preferably subjected to a further succession of steps, in order to realise the closure member  100  previously described. 
     Preferably, therefore, on the laminate  1  at least a first engraving is realised on the second film  30 , such as to form an inner weakening line  102  and extending according to a predetermined geometry. 
     In particular, the second film  30  (and preferably also the further film  60 ) is engraved according to said predetermined geometry, the engraving not affecting the first film  20 . 
     Preferably, the first engraving of the second film  30  takes place along a direction at least partly “in a horseshoe shape”, in order to define at least one area which, in use, is the access gap to the container. 
     In the preferred embodiment, the first engraving passes through the printed pattern “G” of the second film  30 , in order to define the tamper-evident tab “TE” previously described. 
     It is then provided the realisation of at least one second engraving on the second film  30  and at said anti-adhesive strip ( 5 ) so as to define an outer weakening line  103 . Therefore, the second engraving passes through the anti-adhesive strip  5  (and vice versa). 
     Moreover, an engraving of the laminate  1  is provided according to a perimeter having a peripheral edge  100   a  surrounding the weakening lines  102 ,  103  and provided with at least one hand gripping portion  101  for a user. 
     At least at said hand gripping portion  101 , the inner weakening line  102  is far from the peripheral edge  100   a  with respect to said outer weakening line  103 . 
     The invention achieves the intended objects and achieves important advantages. 
     In fact, the provision of a discrete plurality of anti-adhesive strips between the two layers of the laminate greatly facilitates the separation between the two layers and makes the finished product more economical and versatile, since it is no longer necessary to provide adhesive-free longitudinal areas. 
     Furthermore, the realisation of a laminate with an “inner” printed face together with the appropriate geometry of the inner weakening line makes it particularly easy and effective to create areas/tabs defining the warranty seal, a peculiarity that is particularly appreciated by customers.