Abstract:
The invention concerns a method for making packaging bags ( 1 ) with a double wall ( 31; 31 ), characterized in that it comprises steps which consist in: unwinding a first packaging sheet ( 31 ) wherein a window is cut out or precut; unwinding a second packaging sheet ( 32 ) wherein another window is cut out or precut; applying a closure assembly ( 5 ) on the moving packaging sheet, perpendicular to a window; fixing the closure assembly on the packaging sheet; fixing the two packaging sheets one on the other to form a double wall, said sheet being then formed into a packaging bags ( 1 ).

Description:
OVERALL TECHNICAL FIELD  
       [0001]     The invention relates to the field of packaging sachets.  
         [0002]     Numerous packaging sachets and numerous systems for manufacturing them have already been proposed.  
         [0003]     For thin sachets, usually flat, in a filled state, the known means give overall satisfaction. In this case, the sachets are generally made from two flat sheets welded together along three sides and bearing means for sealing, for example complementary male/female sections at the opening of the sachets.  
         [0004]     On the other hand until now, the making of sachets for bulky items, irrespective of their nature, has proved unsatisfactory, despite numerous studies in this very specific field.  
         [0005]     In particular, such sachets often require relatively thick walls, and it is not easy to attach means for sealing to such walls.  
         [0006]     This applying of the means for sealing is all the more delicate when the means for applying are not located at the opening of the packaging sachet, but on a surface of the sachet.  
         [0007]     We have diagrammatically illustrated in the annexed  FIG. 1 a  known technique for manufacturing sachets comprising means for sealing  5  attached to a wall  3  of the packaging sachet  1 , and not at the opening  2  of the packaging sachet.  
         [0008]     The means for sealing  5  are welded or stuck to points  6  on the front wall  3  of the bag  1 .  
         [0009]     The points of application are made on the means for applying  7  of the means for sealing  5 . These means for applying  7  comprise films, for example made in plastic.  
         [0010]     The means for sealing  5  can also comprise means  8  forming runners facilitating the opening and closing of the means for sealing  5 .  
         [0011]     Examples of such known bags are disclosed and illustrated in documents U.S. Pat. No. 4,335,817 and EP 0 843 636.  
         [0012]     The sachets, according to the prior art, however, comprise inconveniences.  
         [0013]     Notably, the points of application  6  are not entirely sound.  
         [0014]     Such sachets do not envisage the applying of means for applying on sachets comprising double-layer walls, that meaning double ply bags.  
       PRESENTATION OF THE INVENTION  
       [0015]     The invention proposes to overcome these inconveniences.  
         [0016]     For this reason the invention proposes a method for manufacturing double-ply packaging sachets characterised in that it comprises the stages according to which: 
        we feed a first packaging sheet on which we cut out a window patch;     we feed a second packaging sheet on which we cut out another window patch;     we attach a set of seals to a fed-through packaging sheet, perpendicular to the window patch;     we attach the set of seals to the packaging sheet;     we attach the two packaging sheets to each other to form a double ply sheet, this sheet then being formed into a packaging sachet.        
 
         [0022]     The invention is advantageously completed by the following characteristics taken singly or in any technically possible combination: 
        we attach the set of seals between the two packaging sheets, so that the means for applying the set of seals are incorporated between the two packaging sheets;     we attach the set of seals to one of the two packaging sheets, the double ply formed by the other packaging sheet not covering the means for applying the set of seals;     we weld the means for applying the set of seals to the packaging sheet;     we stick the means for applying the set of seals to the packaging sheet;     we cut out at least the window patch intended for the external wall of the double ply sachet with a pre-cut dotted line so that the wall of the sachet is capable of forming a seal covering the set of seals on the front of the sachet and being of tamper-proof type prior to the first opening; and     we attach an adhesive strip opposite the window patch of the external wall, this strip thus constituting a tamper-proof element to be stripped off upon the first opening of the sachet.        
 
         [0029]     The invention relates to sachets produced by this method as well as the machines for implementing the method according to the invention. 
     
    
     PRESENTATION OF THE FIGURES  
       [0030]     Other characteristics, purposes and advantages of the invention will be revealed through the description that follows which is clearly illustrative and non restrictive and which must be read in relation to the annexed drawings in which:  
         [0031]      FIG. 1 , already evoked, diagrammatically represents a bag according to the prior art comprising an opening on one single ply wall;  
         [0032]      FIG. 2  diagrammatically represents a front view of a double ply bag comprising an opening on one wall of the bag;  
         [0033]      FIG. 3  represents a first method for applying an opening and a set of fastening between the two sheets of a wall of a double ply bag;  
         [0034]      FIG. 4  represents another method for applying means for sealing on a double ply bag;  
         [0035]      FIG. 5  represents an embodiment where a packaging sachet comprises on its surface means for sealing a pre-cut window patch forming a “tamper-proof strip”;  
         [0036]      FIG. 6  represents an embodiment where a packaging sachet comprises on its surface means for sealing an adhesive strip forming a tamper-proof strip;  
         [0037]      FIG. 7  represents an embodiment in which openings are formed on the upper part of the sachet once filled and thus allows to form a grip handle;  
         [0038]      FIG. 8  represents an embodiment according to which the means for gripping are formed by straps attached to the upper part of the packaging bag; and  
         [0039]      FIG. 9  diagrammatically represents a machine assembly allowing to attach means for sealing and to manufacture double ply bags. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]     As previously indicated the invention relates to the producing of re-sealable sachets using automatic machines, these sachets comprising a double ply wall.  
         [0041]     This invention can apply as much to horizontal feed through automatic sachet production machines as to vertical feed through automatic sachet production machines.  
         [0042]     Furthermore, the invention applies as much to automatic sachet production machines with filling during a stage subsequent to the production and possibly geographically separate from the production site as to production machines with filling and sealing—of “FORM, FILL, SEAL” (FFS) type—on a single site and in successive stages.  
         [0043]     Thus the invention preferably and advantageously applies to FFS type vertical feed through machines.  
         [0044]     We have diagrammatically represented in  FIG. 2 a  bag  1  intended to receive thick contents, which will be for example inserted into the bag  1  by the opening  2 , this bag  1  principally comprising two walls  3  and  4 .  
         [0045]     Such a sachet  1  is formed according to a known technique by the folding on itself of a packaging sheet so as to form a bag. The bag  1  comprises for example, but not obligatorily gussets  9  on its sides. We can advantageously refer to the applicant FR 2 758 761 in order to understand the forming and producing of such sachets.  
         [0046]     We have designated the front wall of the bag  1  with  3  and the rear wall of the bag  1  with  4 .  
         [0047]     The front wall  3  comprises a set of seals  5  this set of seals  5  comprising for example but not obligatorily means  8 , facilitating the opening and the closing of the means for sealing the set  5 . The means  8  will be for example formed by a runner that can be moved along known complementary sealing sections.  
         [0048]     The set of seals  5  can also comprise means for sealing that do not comprise male/female type complementary sealing sections.  
         [0049]     The set of seals can comprise a U-shaped or W-shaped film, or any known shape.  
         [0050]     Additionally, the set  5  can comprise a film covering the means for sealing, and allowing to form a “tamper-proof” type film. The film is opened upon the first opening of the sachet by the tearing of a line of weakness made in the film material, this line of weakness can comprise dotted lines.  
         [0051]     The walls of sachet  1  comprise two pieces, called plies. We have designated in  FIG. 2  the exterior ply of the wall  3  with  31  and the interior ply of the wall  3  with  32 . We have also designated the exterior ply of the wall  4  with  41  and the ply of the wall  4  with  42 , the ply  42  being on the inside of the sachet  1 .  
         [0052]      FIG. 3  diagrammatically represents the attaching the set of seals  5  to the inside of the double ply wall  3 .  
         [0053]     According to the invention, the set of seals  5  comprises means for applying  7 . These means for applying  7  will be for example formed by side films, in whatsoever material. The side films can thus be composed of typical material, but also of paper or carton type material.  
         [0054]     According to the invention, these means for applying  7  are attached at points  6  to the wall of the bag  1 .  
         [0055]     The points of application  6  comprise, according to a first embodiment represented in  FIG. 3 , a first point of application  61  which attaches the means for applying  7  to the ply  31 , and a second point of application  62  attaching the means for applying  7  to ply  32 .  
         [0056]     This embodiment has the advantage over the embodiment of the prior art of allowing the very sound attachment of the set of seals  5  to a double ply bag.  
         [0057]     In  FIG. 3 , we have represented a set of seals  5  comprising means forming male/female type complementary sections  10  as well as means forming the runner  8  allowing to easily open and close these means for sealing  10 .  
         [0058]     The runner can be in either metal or plastic.  
         [0059]     Other means for sealing can obviously be attached to such a wall  3 , for example means that do not comprise sealing runners, or means for sealing that do not comprise complementary sections.  
         [0060]      FIG. 4  represents another embodiment for the attachment of a set of seals  5  to a wall  3 .  
         [0061]     According to this embodiment, the wall  3  comprises points of application  6  which are not overlaid.  
         [0062]     Indeed, the means for applying the set  5  are attached to ply  31  by a point of application  61 , even though they are not attached to ply  32  of the wall  3 .  
         [0063]     In the embodiment represented in  FIG. 3 , the ply  32  does not have exactly the same dimensions as ply  31 . In other words, the cut-out window patch in ply  32  allowing a user to gain access to the inside of the bag has greater dimensions than the window patch pierced in ply  31  of the bag  1 , the latter window patch allowing access to means for sealing the bag.  
         [0064]     The ply  32  is attached to ply  31  by points of application indicated by  63  in  FIG. 4 .  
         [0065]     In  FIG. 4 , we have represented means for sealing that do not comprise opening and closing runners. The means for sealing comprise male/female type complementary sections, but an alternative to this embodiment comprising means for sealing that do not have such sections is conceivable.  
         [0066]      FIG. 5  represents an alternative to the embodiment represented in  FIG. 3 . According to this alternative, the ply  31  does not comprise an opening allowing direct access for the user to the set of seals  5 .  
         [0067]     According to this alternative, the window patch  33  is pre-cut out of the ply  31 , without being totally open. Thus, the means for sealing  5  are not accessible from the outside of the sachet. The pre-cut window patch  33  thus constitutes a “tamper-proof” type seal allowing to indicate to the user that the sachet has never been opened.  
         [0068]     Come the first opening of the sachet  1 , the user will cut the tamper-proof window patch  33  along the dotted line on the ply  31 . For this reason, the dotted line constitutes a line of weakness in the ply  31  allowing to easily open the tamper-proof window patch  33 .  
         [0069]     The pre-cut dotted line can be of another type, for example a line of weakness with a lesser thickness in the case for example of plies made in plastic.  
         [0070]     In  FIG. 5 , the tamper-proof window patch is located on the ply  31 . We can also envisage placing a tamper-proof window patch on the ply  32 , retaining or not the tamper-proof type window patch on the ply  31 .  
         [0071]      FIG. 6  represents another alternative of the sachet represented in  FIG. 3 , according to which the tamper-proof window patch is no longer constituted of a pre-cut window patch on the ply  31 , but is constituted of an adhesive strip  33  which is stuck to the perimeter of the window patch open in the ply  31 , the stickiness being made via the points of application  64  located on the exterior of the sachet.  
         [0072]     This relatively strong stickiness allows to form a perfect tamper-proof type seal perpendicular to the set of seals  5 .  
         [0073]     This adhesive strip  33  can be constituted of a plastic type material.  
         [0074]     As in the alternative represented in  FIG. 5 , this adhesive strip can also be stuck to the wall on the inside of the bag on the ply  32 . The choice of an adhesive strip on the ply  31  and/or  32  is made independently from each other.  
         [0075]     We can also for example place an adhesive strip, as represented in  FIG. 6 , on a tamper-proof window patch of the type represented in  FIG. 5 .  
         [0076]      FIG. 7  represents a bag according to the invention in which we have pierced two window patches  10  in the upper part allowing to form means for gripping so as to carry the packaging bag.  
         [0077]      FIG. 8  represents an alternative according to which the means for gripping are constituted of straps  11 .  
         [0078]     The attaching of the straps or cords  11  can be ensured via sticking or via stringing said straps in holes made in the upper part of the sachet. The stringing is followed by a stage in which we stick on the upper part of the sachet or we tie the straps in the purposely made holes.  
         [0079]     Alternatively, the bag could only comprise a single strap or cord forming a handle.  
         [0080]     The walls of the packaging bag can be indiscriminately made in plastic material, paper or carton type material. The walls can for example be constituted of an interior ply in a material, the exterior ply being in another material.  
         [0081]      FIG. 9  diagrammatically represents a machine allowing to perform the method of forming and manufacturing sachets according to the invention.  
         [0082]     A first packaging sheet  31  is reeled off a paper roller  92 .  
         [0083]     In stage  94 , a window patch is pierced or pre-cut.  
         [0084]     At point  95 , a set of seals  5  is attached perpendicular to the pierced or pre-cut window patch.  
         [0085]     In stage  96  we weld or stick the means for applying the set of seals to the perimeter of the pierced or pre-cut window patch. The stage  96  can for example be carried out thanks to the feeding through of the sheet between two feed-through rollers visible in  FIG. 9 .  
         [0086]     We are mindful that the set of seals is of any type and that it does or does not comprise a runner.  
         [0087]     Simultaneous to the feeding through of the sheet  31 , a packaging sheet  32  is reeled off the roller  91 .  
         [0088]     In stage  93  we pierce or pre-cut a window patch of similar size or of a different size to the pierced or pre-cut window patch at point  94 , according to the embodiment that we wish to obtain (see  FIGS. 3 and 4 ).  
         [0089]     The sheet  32  continues to be reeled off so as to simultaneously arrive at point  97  with the sheet  31 . At this stage, we back the sheet  32  to the sheet  31  so as to obtain a double ply packaging sheet.  
         [0090]     The piercing or pre-cutting of the window patches at stages  93  and  94  is synchronized, so that the window patches lie perpendicular to each other when they arrive at point  97 . The stage  97  can for example be carried out thanks to the feeding through of the sheets between two feed-through rollers visible in  FIG. 9 .  
         [0091]     We envisage starting from point  98  methods and machines for lateral welding so as to form the bag, with or without side gussets, its filling before sealing the upper opening of the bag.  
         [0092]     Stage  98  can also comprise the piercing of the means for gripping of handle type or the attaching of straps and cords forming means for gripping. It can be carried out at a different site than that of the stages represented in  FIG. 9 , at times near or relatively distant.  
         [0093]     We are mindful that the diagram in  FIG. 9  does not whatsoever assume the position of the machine. For example, it could be a vertical or horizontal feeding through and that the attaching of the set of seals  5  can be carried out longitudinally or transversally to the feeding through of the packaging sheet  31 .