Patent Publication Number: US-2020299042-A1

Title: Bag- or sack-like packaging and process for manufacturing bag- or sack-like packaging

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application, filed under 35 U.S.C. § 371, of International Application No. PCT/BR2018/050380, filed Oct. 17, 2018, which claims priority to Brazil Application No. BR102017022412-0, filed Oct. 18, 2017, the contents of both of which as are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The present invention refers to a bag- or sack-type packaging having a body made of polyethylene or polypropylene film and a raffia cover, particularly applicable in the storage and transport of powdered material, grain, bran, flakes, among other materials, the construction of which prevents the use of glue in its manufacture, hence promoting easy and efficient recycling of the packaging and a final package shape that is favorable to storage and palletization as well as enables automation of its manufacturing process. 
     The present invention further refers to a process for manufacturing a bag- or sack-type packaging, as above. 
     Description of Related Art 
     The package body, which delimits the volume of material to be stored, comprises longitudinal openings that have to be closed to allow the package to be filled with material and to retain the same in its interior. Closure of such openings can be made by sewing or welding their edges, or even gluing closing covers on these openings. 
     Welded packaging is an improvement over sewn packaging, not only due to advantages in manufacture, but mainly because of the greater resistance to entry of moisture caused particularly by the fact that the packaging wall does not need to be perforated as is the case of sewn packaging. 
     The use of covers for closing the openings or for other purposes is also a viable option from the point of view of sealing, also having the advantage of providing a shape (usually substantially rectangular) that is suitable for palletization and storage, that is, stacking and transporting packages using pallets, or even for stacking and storing the product itself. 
     In general, application of raffia covers being welded to sack-type packages having a body made of raffia is already known in the state of the art. However, application of welded covers to sacks having a body made of polyethylene or polypropylene film is still unsolved, particularly concerning welding of raffia covers to a polyethylene or polypropylene film body. In other words, there is still no solution for welding a raffia cover onto a body made of film. It is understood herein that a film is not distinct from raffia, which means that the body of the present invention is free of raffia. 
     With regard to the industrial scale process, the only solution that currently exists uses the closure with a cover, but which requires glue to be applied on the openings to attach the cover. Unfortunately, the presence of glue prejudices the process of recycling the packages, sometimes reducing recycling efficiency as it requires the disposal of glue-containing packaging parts to avoid contamination of the recycled polymer. 
     Moreover, still concerning the application of covers to the package, the gluing process imposes difficulties in the automation process due to comprising folding the ends of the package and applying glue to these folds. This fold is a process that requires precision and whose complexity increases greatly with the need to apply glue for bonding the covers, since stability of the folded region is naturally impaired at the time of application. Thus, in addition to the additional cost of the glue, there is also an industrial scale reduction caused by the step of applying the glue. 
     That being said, packages having welded openings (without cover) also bring issues related to manufacture and use, because their filled shape comprises bulging longitudinal ends that make storage difficult (by stacking, for example) as compared to a rectangular shape, such as that obtained by using a glued cover. 
     An additional difficulty in the state of the art concerns the fact that it is not yet possible to weld a raffia cover of a material other than that of the film of the body, that is, to weld a raffia cover of polypropylene fabric to a film body containing at least one layer comprising predominantly polyethylene or, alternatively, to weld a raffia cover of polyethylene fabric on a film body containing at least one layer comprising predominantly polypropylene. 
     Thus, the state of the art does not provide a bag- or sack-type packaging having a body made of polyethylene or polypropylene film and a welded raffia cover that provides concomitantly easy recycling, a shape that facilitates storage and also allows automation of the manufacture process without incurring the problems observed in automation of the application of the cover using glue. 
     BRIEF SUMMARY 
     A first object of the present invention is to provide a bag- or sack-type packaging having a film body and a cover closure, particularly with a raffia cover. 
     A second object of the present invention is to provide a bag- or sack-type packaging having a polyethylene film body and a closure with a polyethylene raffia cover, or a polypropylene film body and polypropylene raffia cover closure, or a polyethylene film body and a polypropylene raffia cover closure, or a polyethylene film body and a polypropylene raffia cover closure. 
     A third object of the present invention is to provide a bag- or sack-type packaging that solves the issue of welding materials having different chemical parities. 
     A forth object of the present invention is to provide a bag- or sack-type packaging that enables one to weld a raffia cover of a material other than that of the body film, that is, to weld a raffia cover of polypropylene fabric to a film body containing at least one layer comprising predominantly polyethylene or, alternatively, to weld a raffia cover of polyethylene fabric to a film body containing at least one layer comprising predominantly polypropylene. 
     A fifth object of the present invention is to provide a bag- or sack-type packaging having a film body and a cover closure particularly made of raffia that allows it to be easily and efficiently recycled. 
     A sixth object of the present invention is to provide a bag- or sack-type packaging that enables easy palletization and storage. 
     A seventh object of the present invention is to provide a bag- or sack-type packaging whose manufacture can be easily automated. 
     The present invention refers to a bag- or sack-type packaging provided with a body made of a polymeric material film and provided with at least one cover comprising, at least in part, raffia, the cover being attached to the body by welding. 
     In particular, the cover comprises an outer layer comprising raffia and at least one inner layer comprising a polymeric material weldable to the body. Alternatively, the packaging can be provided with an intermediate film formed by at least a first and a second layers associated with each other, the first layer comprising a polymeric material weldable to the body and the second layer comprising polymeric material weldable to the cover. 
     Still particularly, the body film comprises predominantly polyethylene, the raffia of the cover comprises polyethylene, and the inner layer comprises at least in part polyethylene. 
     Alternatively, the body film comprises predominantly polyethylene, the raffia of the cover comprises polypropylene, the first layer comprises polyethylene, and the second layer comprises a mixture of polyethylene and polypropylene. 
     The present invention further refers to a process for manufacturing a bag- or sack-type packaging, comprising the steps of:
         laminating a cover comprising raffia; and   welding the cover on a body.       

     In particular where the raffia of the cover comprises polypropylene and the body comprises predominantly polyethylene, the process further comprises the steps of:
         welding an intermediate film provided with at least a first and a second layers to the body and the cover.   welding a first layer comprising polyethylene to the body; and
 
welding a second layer comprising at least in part polypropylene to the cover.
       

    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The present invention will be described in more detail based on an exemplary embodiment represented in the drawings. The figures show: 
         FIG. 1 —is a perspective view of the packaging of the present invention; 
         FIG. 2 —is a perspective view of the packaging of the present invention with one of its ends folded and closed by a cover; 
         FIG. 3 —is a schematic representation of a preferred composition of the packaging cover of the present invention; 
         FIG. 4 —is a schematic representation of a preferred composition of the packaging of the present invention; and 
         FIG. 5 —is a schematic representation of an alternative composition of the packaging of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     The present invention refers to a bag- or sack-type packaging whose composition of elements allows them to be automatically attached to each other by welding without using glue, giving advantages according to the objects of the invention. 
     For a better understanding of the present invention, the term “raffia” should be understood as a synthetic compound that forms an interwoven fabric. Commonly, raffia comprises a polyethylene or polypropylene fabric, or even a mixture of both. Nevertheless, the present invention can be carried out using raffia comprising other polymers or polymer mixtures without harming or altering the proposed technical effect. 
       FIGS. 1 and 2  illustrate the package of the present invention in its preferred upright and lying configurations with folded ends, respectively. The packaging essentially comprises a body  10  formed by a polymeric film and able to receive the material to be stored. Preferably, such a body  10  comprises a thin wall, or film, which delimits an inner region where the material will be stored. The body  10  can comprise a cylindrical, rectangular, or any other shape suitable for receiving and storing material. 
     Preferably, the body  10  comprises a film of at least one layer of polymeric material that can receive and store material, exhibiting good mechanical strength and imposing no risk of contamination of its contents. In a particular embodiment, the body  10  is composed predominantly of polyethylene. 
     For a better understanding of the invention, the term “predominantly” should be understood as an amount of polyethylene greater than 50% of the body  10  volume. Polyethylene distribution in the body  10  can be made in various ways, it can be entirely made of polyethylene, or even have one or more “sleeves” (inner layers) made of polyethylene, or even outer polyethylene layers adjacent to layers made of other polymers. 
     In another particular construction, the body  10  can be composed of more than 60% polyethylene, or even more than 70% polyethylene, or even more than 80% polyethylene, or even more than 90% polyethylene. The greater the minimum polyethylene limit used in the body  10  composition, the greater the body  10  flexibility, thus justifying different limit ranges for applications that require more or less flexibility of the packaging of the present invention. 
     In another particular embodiment, the body  10  may be composed entirely of polyethylene, or even a mixture of polyethylene and polypropylene. The body  10  can also be comprised of multiple layers forming its film, wherein each layer can also be a mixture of polyethylene, polypropylene or a mixture thereof and can also contain additives. The additives used can be of several types, such as pigments, flow auxiliaries, antioxidants and other materials to aid in the manufacture process and/or to promote better welding performance. 
     In a particular construction of the present invention, the body  10  can comprise at least one opening  11 . In general, such an opening  11  is a result of the manufacture process commonly used to produce sacks, which consists of printing a film of a material that forms the body  10  with the inner region that will receive the material being delimited. As an example, mention can be made of printing a cylinder made of polyethylene/mixture of polyethylene and polypropylene which will thereafter generate a cylindrical packaging. The opening  11  ends can be folded on themselves as seen in  FIG. 2 , to form a preliminary closure and facilitate the final closure, as will be seen below. 
     Essentially, the package comprises at least one cover  20  made of raffia, the cover  20  being attached to the body  10  by welding. This feature of the invention addresses the problem of the state of the art that the attachment of covers on the package body requires the use of glue for an acceptable attachment, which affects recycling of the packaging. This feature also addresses the issue of the difficulty in automating the process of attaching the cover  20  to the body  10  by gluing due to the complex automation of the application of glue on the fold without impairing its stability. To solve this problem, the present invention provides a cover  20  welded to the body  10 . 
     For a better understanding the present invention, the term “welding” should be understood as the process of joining two polymers by applying heat at their interfaces and subsequently heating to join their surfaces. Heating is carried out until the point of softening of the material to be welded. It should be understood here that welding is different from fusion. In welding the material is adhered in solid state and in fusion the materials are anchored to each other in liquid state and are joined together upon solidification. 
     Construction of the packaging of the present invention using a cover  20  welded to the body  10  provides an advantageous end “palletizable” shape of the packaging (in general, substantially rectangular and suitable for stacking, transport and storage, either on pallets or not) without the need for using glue, thus allowing easy storage and transport and easier and more efficient recycling of the packaging. In addition, the present invention also eliminates the difficulties in automating the process of gluing the cover to the body, allowing automatic welding (a much more stable attachment process) of the cover to the body. 
     However, welding the cover  20  to the body  10  of the packaging of the invention is not sufficient to achieve the technical effects proposed by the invention. If a cover  20  made of a polymer film is welded against a body  10  also made of a polymer film, several problems arise depending on the material used. For example, in more flexible polymers (such as polyethylene) having low weldability (ease of performing the welding operation), as they comprise, for example, a very low softening temperature and welding of a thin film cover over the fold results in deformation (wrinkling) of the cover resulting in poor closure. 
     On the other hand, the use of polymers having greater weldability (such as polypropylene) in general does not meet the strength and flexibility requirements of a sack-type packaging, that is, the final packaging cannot be used in many of the required applications for this type of packaging, such as transporting heavy weights and constant handling by people and machines. 
     Thus, the packaging of the present invention further comprises the cover  20  being composed of raffia. Raffia fabric has an interwoven structure that provides it with greater weldability, even though raffia is composed of materials that originally exhibit low weldability, such as polyethylene. Thus, the cover  20  can be welded to the body  10  film without deforming said cover  20 . 
     Thus, the cover  20  made of raffia and welded to a body  10  formed by a film of polymeric material provides a packaging that does not require the use of glue, can be easily manufactured in an automated manner, the cover can be welded to the body without being deformed, and has a favorable shape for storage and palletization. 
     In a particular construction of the package, as seen in  FIG. 2 , the covers  20  can be welded to one or both longitudinal ends of the body  10  where the openings  11  are located to allow closure of the package, even though the cover can be attached to other regions of the body  10 . In particular, the cover  20  is attached to the body  10  at each of its longitudinal ends, over the openings  11 . In a possible embodiment of the body  10 , more than one cover  20  is attached to the body  10  to cover multiple regions of interest, such as, for example, one cover  20  for each of the openings  11 . 
     In a preferred embodiment of the cover  20  of the present invention, shown in  FIG. 3 , the cover  20  comprises an inner layer  21  and an outer layer  22 . For a better understanding of the cover  20  construction in such a preferred embodiment, the inner layer  21  consists of the layer that is in contact with and is welded to the body  10  film, while the outer layer  22  is the one facing the external environment and is arranged on the opposite side with respect to the inner layer  21 . 
     The outer layer  22  is particularly composed at least partially of raffia, and the inner layer  21  is composed of any polymer material, or a mixture of polymeric materials. Preferably, the inner layer  21  is a lamination layer, which aids in welding the cover  20  to the body  10 . The inner lamination layer  21  can be applied to the outer raffia layer  22  by means of a polymeric lamination process, where a melted polymer is drained over the outer raffia layer  22  forming the inner layer  21 . In particular, the lamination layer is composed of the same polymeric material as the inner layer  21 , and it can also be a mixture of polypropylene or polyethylene, or even polyethylene alone, polypropylene alone or other materials such as EVA (ethylene and vinyl acetate copolymer). 
       FIG. 4  shows a preferred embodiment of the attachment between the cover  20  and the body  10 . The inner layer  21  is arranged adjacent the body  10 . In this preferred embodiment, the inner layer  21  of the cover  20  is the one that will be welded to the body  10  and, therefore, there must be chemical parity between the layer  21  and body  10  materials to enable welding attachment. As previously explained, the body  10  is preferably composed of a film made predominantly of polyethylene, such that layer  21  should preferably comprise polyethylene. In this preferred embodiment, the raffia cover  20  comprises polyethylene in order to enable chemical parity between the inner and outer layers  21 ,  22  during the lamination process. 
     In an alternative embodiment of the present invention shown in  FIG. 5 , the package comprises an intermediate film  30  provided with at least a first and a second layers  31 ,  32 . This alternative embodiment is particularly applicable in instances where the raffia cover  20  is composed of a material that does not exhibit chemical parity with the body  10  material, and in such an instance, even using the laminated inner layer  21 , a reliable welding attachment would not be possible. 
     Thus, the intermediate film  30  acts to aid in chemical parity between the the cover  20  and body  10  materials, the first layer  31  being weldable to the body  10  and the second layer being weldable to the cover  20 . More particularly, the second layer  20  is weldable to the inner layer  21  of the cover  20 . 
     More particularly, preferably, but not obligatorily, the intermediate film  30  comprises a thickness ratio of 20%, 80%, respectively, relative to the sum of thicknesses of these two layers. Even more particularly, the inner layer comprises, preferably, but not obligatorily, a ratio of 15% to 40% polyethylene and 60% to 85% polypropylene or vice versa depending on the film material of the sack body. 
     In a possible construction of this alternative embodiment, the outer  22  and inner  21  layers of the cover  20  are composed of polypropylene raffia and polypropylene, respectively, and the body  10  is predominantly composed of polyethylene. The intermediate film  30  is then formed by a first layer  31  made of polyethylene, allowing it to be welded to the body  10 , and the second layer  32  is composed of polypropylene or a mixture of polyethylene and polypropylene, which allows it to be welded to the inner layer  21  of the cover  20 . Welding the intermediate film  30  to the body  10  and the cover  20  provides a package that achieves the objects proposed by the present invention, even when the cover  20  and body  10  materials do not exhibit chemical parity. 
     It is further clarified that the cover  20  of the present invention may comprise any number of inner layers  21  with any composition of polypropylene, polyethylene or a mixture thereof, depending only on the intended application, provided that the arrangement and composition of the layers allow the attachment of the cover  20  to the body  10 , either using the intermediate film  30  or not. 
     In addition, the intermediate film  30  can also comprise any number of layers, not just a first and a second layers. The number of layers of the intermediate film  30  will depend on the type of intended application and on other functions to be fulfilled thereby, besides enabling welding between the cover  20  and the body  10 , such as the function of filling the packaging film or thermal insulation. For such functions, additional layers can be used in the intermediate film without affecting its proposed function. 
     In a particular embodiment of the present invention, the body  10  is attached to a valve  30 . As seen in  FIGS. 1 and 2 , the valve  30  is attached to the body  10  through one of its openings  11 , and is intended to allow the filling and subsequent closing of the package. 
     In particular, the valve  30  comprises raffia and is welded to the body  10 , achieving the same benefits of welding the raffia cover  20  onto the body  10 . In this case, the valve  40  must have a composition that would allow it to be welded to the body  10 , either using an intermediate film  30  or not, as is done for the cover  20 . In a possible construction, the valve  40  may comprise an outer layer  42  composed of raffia and an inner layer  41  composed of a polymer weldable to the body  10 , or to one of the intermediate film  30  layers. As with the cover  20 , the valve  40  can be composed of multiple inner layers depending on the desired application. 
     The layer arrangement shown in  FIGS. 3, 4 and 5  can be applied not only to the cover  20 , but also to the valve  40 . According to the preferred embodiment of the body  10  composed predominantly of polyethylene, the inner  41  and outer  42  layers of the valve  40  are composed of polyethylene and polyethylene raffia, respectively. In an alternative embodiment where the raffia valve  40  comprises a material exhibiting no chemical parity with the body  10  material, an intermediate film  30  is used, having a first layer  31  of a material weldable to the body  10  and a second layer  32  of a material weldable to the inner layer  41  of the valve  40 . 
     In accordance with the bag- or sack-type packaging described above, the present invention also refers to a process for the manufacture of this packaging, essentially comprising the steps of:
         laminating a cover  20  comprising raffia; and   welding the cover  20  on a body  10 .       

     Lamination of the cover  20  composed of raffia consists of adding the inner layer  21  by polymeric lamination, as previously discussed. Welding of the cover  20  to the body  10  is carried out by heating the region between the body  10  and the cover  20  and subsequently arranging them in contact with each other. Also, as already discussed, such welding process can be automated. 
     For instances where the cover  20  comprises a material having no chemical parity with the body  10  material, the process can particularly further comprise the following step:
         welding an intermediate film  30  provided with at least a first and a second layers  31 ,  32  to the body  10  and the cover  20 .       

     Even more particularly, the process further comprises the following steps:
         welding a first layer  31  comprising polyethylene to the body  10 ;   welding a second layer  32  comprising at least in part polypropylene to the cover  20 .       

     The aforementioned process further comprises the characteristics of the already described materials, such as the fact that the intermediate film  30  comprises a thickness ratio of 20%, 80%, respectively, relative to the sum of thicknesses of both layers. Even more particularly, the inner layer comprises, preferably, but not obligatorily, a ratio of 15% to 40% polyethylene and 60% to 85% polypropylene or vice versa depending on the film material of the sack body. 
     Having described a preferred exemplary embodiment, it should be understood that the scope of the present invention covers other possible variations, being limited only by the content of the appended claims, including possible equivalents thereof.