Abstract:
The invention relates to a closure assembly ( 1 ) comprising complementary closure sections ( 2 ) and panels ( 6   a   , 6   b ) for fixing said closure assembly to the internal faces of a bag. The inventive assembly is characterised in that it comprises: sealing bands ( 11, 13 ) which are disposed on the external faces of the fixing panels ( 6   a   , 6   b ); a precut or line of weakness ( 10 ) which is made in one of the fixing panels ( 6   a ) and which divides said panel ( 6   a ) into a first external part ( 61   a ) and a second internal part ( 62   a ), the sealing band on the panel being limited to the external part of same; and a sealing band ( 12 ) which is disposed on the internal face of at least one of the panels, each internal sealing band being disposed on the internal part of the fixing panels.

Description:
GENERAL TECHNICAL FIELD  
       [0001]     The present invention concerns the field of packaging bags.  
         [0002]     It concerns in particular the manufacture of bags comprising closure assemblies, in particular closure assemblies of the tamper-evident type.  
         [0003]     Many packaging bags and many systems for manufacturing these have already been proposed, in particular for fixing to bags closure assemblies comprising tamper-evident means.  
         [0004]      FIG. 1  shows an example of a known closure assembly  1 . It comprises complementary profiles  2  for opening and closing the mouth  3  of a bag. The complementary profiles  2  are advantageously opened or closed by virtue of a moving slider  4 .  
         [0005]     There can also be seen in  FIG. 1  means providing the initial protection and a function of opening tell-tale, consisting of a strip  5  which extends initially across the mouth of the bag and which must be broken to gain access to the content of the latter.  
         [0006]     The tamper-evident means  5  are known per se and enable a user to know whether or not the bag containing the product has already been opened. Fixing sheets  6  make it possible to fix the complementary profiles to the walls  7  of the bag.  
         [0007]     The fixing of the sheets  6  takes place during a welding process, during which the fixing sheets pass between welding jaws  8 .  
         [0008]     The fixing of the sheets to the mouth of the bag does not prove completely satisfactory, although many researches have been conducted in this very special field.  
         [0009]     In particular the fixing sheets must not be welded together, nor to the tamper-evident means.  
         [0010]     Thus it is necessary to provide an intermediate part  9  between the internal faces of the sheets, which makes it possible to correctly position the tamper-evident means  5  or prevent the welding of the sheets  6  together.  
         [0011]     Examples of such known bags are described and illustrated in the documents FR 2 778 362.  
       PRESENTATION OF THE INVENTION  
       [0012]     The invention proposes to improve the system for fixing the sheets to the faces of the bag.  
         [0013]     It in particular also proposes closure assemblies, the tamper-evident means of which do not consist of a sheet comprising a weakness line.  
         [0014]     To this end the invention proposes a closure assembly comprising complementary closure profiles and sheets for fixing the closure assembly to the internal faces of a bag, characterised in that it comprises: 
        welding strips on the external faces of the fixing sheets;     a scoring or weakness line formed in one of the fixing sheets, the said scoring or weakness line delimiting the said fixing sheet in a first external part and a second internal part, the external welding strip provided on the sheet being limited to the external part thereof;     a welding strip on the internal part of at least one of the sheets, each internal welding strip being situated on the said internal part of the fixing sheets.        
 
         [0018]     The invention is advantageously supplemented by the following characteristics taken alone or in any one of their technically possible combinations: 
        the external welding strip of the sheet not comprising the scoring extends over the entire width of the sheet;     the external welding strip of the sheet not comprising the scoring extends only over the external part of the sheet;     the closure profiles are complementary, of the male/female type;     the closure profiles comprise a movable slider.        
 
         [0023]     The invention also concerns the bags comprising the closure assemblies according to the invention, the methods and the machines for manufacturing the closure assemblies and the bags comprising these assemblies. 
     
    
     PRESENTATION OF THE FIGURES  
       [0024]     Other characteristics, aims and advantages of the invention will emerge from the following description, which is illustrative and non-limiting and which must be read with regard to the accompanying drawings, in which:  
         [0025]      FIG. 1 , already commented on, depicts schematically a bag according to the prior art comprising a closure assembly with a tamper-evident sheet comprising a weakness line;  
         [0026]      FIG. 2  depicts schematically a closure assembly according to the invention;  
         [0027]      FIG. 3  depicts schematically a closure assembly in place on the mouth of a plastic bag;  
         [0028]      FIG. 4  depicts a closure assembly according to the invention, the tamper-evident element of which has been opened;  
         [0029]      FIG. 5  depicts an embodiment where the packaging bag is filled after the fixing of the closure element;  
         [0030]      FIG. 6  depicts a closure assembly, the fixing strip of which is on the opposite sheet compared with the embodiment depicted in  FIG. 2 ; and  
         [0031]      FIG. 7  depicts a closure assembly combining the embodiments of  FIGS. 2 and 6 .  
     
    
     DETAILED DESCRIPTION  
       [0032]     As indicated previously the present invention concerns the manufacture on an automatic machine of assemblies for closing reclosable bags, these bags comprising a closure assembly with fixing sheets for forming tamper-evident means.  
         [0033]     The present invention can apply equally well to automatic bag making machines with horizontal travel and to automatic bag making machines with vertical travel.  
         [0034]     In addition, the present invention applies equally well to automatic bag making machines with filling during a step subsequent to the manufacture and possibly separated geographically from the place of manufacture, and to manufacturing machines, with filling and closure—of the “Form, Fill and Seal” (FFS) type according to the English terminology generally used—at a single place and during successive steps.  
         [0035]     Thus the present invention preferably and advantageously applies to machines of the FFS type with vertical travel.  
         [0036]      FIG. 2  depicts schematically a closure assembly  1  according to the invention.  
         [0037]     It comprises complementary profiles  2  allowing the opening and closure of the mouth of a bag.  
         [0038]     The complementary profiles  2  are advantageously opened or closed by virtue of a moving slider  4 . The assembly may however not include a slider.  
         [0039]     The complementary closure profiles  2  are advantageously of the male/female type. It is however possible to envisage other types of complementary profile.  
         [0040]     Fixing sheets  6   a  and  6   b  support the profiles  2  and make it possible to fix them to the walls of a bag.  
         [0041]     A weakness line or scoring  10  parallel to the profiles is formed on one of the sheets  6   a . The scoring  10  extends substantially at the middle of the sheet  6   a . It thus divides the sheet  6   a  into two parts: a first part  61   a  outermost with respect to the bag and a second innermost part  62   a.    
         [0042]     By analogy, in the content of the present application, for the second sheet  6   b , the part  61   b  will be called the “external part” and the part  62   b  the “internal part”.  
         [0043]     In the present description, the expression “welding strip” encompasses all possibilities of fixing a fixing sheet to a wall of a bag, such as for example thermal welding, in particular welding of the “hot melt” type, but also adhesive bondings.  
         [0044]     The external face of the external part  61   a  of the sheet  6   a  is covered with a welding strip  11 . The strip  11  is able to fix the sheet  6   a  to the internal face of a wall of a bag.  
         [0045]     The internal face of the part  61   a  on the other hand has no welding strip. The same applies to the internal face of the part  61   b . Thus the internal faces of the parts  61   a  and  61   b  cannot be welded together. According to one variant, the material of the fixing sheets is such that the internal faces do not adhere to each other during a welding process. It is possible to obtain the same result by virtue of a surface treatment process known to persons skilled in the art.  
         [0046]     The internal face of the part  62   b  is covered with a welding strip  12 , which faces the part  62   a  which is covered or not with a welding strip. Advantageously, the part  62   a  does not comprise a strip, which makes it possible to save on welding material and to carry out relatively clean weldings. Naturally the welding strip can be fixed to the part  62   a , and not to  62   b .  FIGS. 6 and 7  differ from  FIG. 2  only through the placing of the welding strip on the internal part of the sheets Ga and  6   b.    
         [0047]     Thus the parts  62   a  and  62   b  can be welded to each other during the passage of the closure assembly between welding shoes.  
         [0048]     The purpose of such a welding is to form an element of the tamper-evident type, which fulfils the role of tell-tale on first opening.  
         [0049]     The external face of the sheet  6   b  is covered with a welding strip  13  able to provide the fixing of the sheet  6   b  to the internal face of a bag.  
         [0050]      FIG. 3  depicts schematically the top part of a bag  20  comprising at its mouth  3  a closure assembly  1  according to the invention. The fixing of the sheets  6   a  and  6   b  takes place during a welding or adhesive bonding process during which the sheets  6   a  and  6   b  pass between welding-or bonding jaws  8 .  
         [0051]     After the welding, the external faces of the sheets  6   a  and  6   b  are fixed to the internal faces of the walls  7  of the reclosable bag  20 . In the same way, the thermal welding process welds together the internal faces of the parts  62   a  and  62   b . The assembly  1  therefore constitutes a closure of the tamper-evident type, the weld  12  being hermetic.  
         [0052]     This tamper-evident closure can be opened by a user by virtue of the scoring  10 .  
         [0053]      FIG. 4  depicts schematically the functioning of the opening after the first opening of the tamper-evident device, that is to say after the cutting of the scoring  10 .  
         [0054]     After the opening of the profiles  2  by virtue of the slider  4 , the user exerts sufficient force on the sheets  6   a  and  6   b  in order to rupture the weakness line or scoring  10 . After the rupture of the weakness line or scoring  10 , the part  62   a  remains welded to the sheet  6   b , the part  61   a  remains welded to the wall of the bag  20 .  
         [0055]     The arrow  21  shows schematically that the user can have access to the inside of the bag  20 . The user can therefore open or close the profiles  2  as he intends.  
         [0056]     The invention also concerns the manufacture of the assemblies  1 . According to this manufacturing method, complementary profiles  2  are welded onto the fixing sheets  6   a  and  6   b . The fixing sheets  6   a  and  6   b  can also be extruded in one piece on the profiles.  
         [0057]     A scoring is carried out or a weakness line  10  is produced in one of the fixing sheets, which is referenced  6   a  for clarity of the description.  
         [0058]     Welding strips are then applied to the sheets  6   a  and  6   b.    
         [0059]     The welding strips on the external faces of the sheets extend over the external part of the sheet  6   a  with respect to the scoring or weakness line  10  and over the entire face for the sheet  6   b.    
         [0060]     The welding strips on the internal faces of the sheets extend over the internal part of the sheet or sheets  6   a  and/or  6   b  with respect to the scoring or weakness line  10 . The internal faces of the external parts with respect to the scoring  10  do not comprise any welding strip. Advantageously, only an internal part comprises a welding strip.  
         [0061]     The complementary profiles advantageously comprise a movable slider for assisting with opening/closing. The slider can be made from metal or plastic.  
         [0062]     The walls of the bags can be made from any material such as plastics material, cardboard or paper.  
         [0063]     The invention also concerns a method of fixing closure assemblies to the mouths of reclosable bags.  
         [0064]     According to this method, the closure assembly is made to pass at the mouth of the bag, which is formed by means known per se, the movement taking place between welding shoes. The welding shoes enable the welding strips to be fixed to the walls of the bag and to weld the internal parts of the fixing sheets together.  
         [0065]     The welding of the fixing sheets to the internal faces of the walls of the bag can take place simultaneously on the two walls, or it is possible to weld a first sheet, carry out various operations, such as the filling of the bag for example, and then weld the second sheet.  
         [0066]     The machines for manufacturing the closure assemblies comprise means able to apply the welding strips to the appropriate faces of the fixing sheets. They also comprise means able to form a weakness line or a scoring on one of the fixing sheets.  
         [0067]     The machines for fixing the closure assemblies to the mouth of the bags comprise means able to make the closure assemblies pass level with the mouth of the bags, and between means able to weld the fixing assemblies to the walls. These means can in particular comprise welding shoes. The movement means can be longitudinal movement means or transverse movement means.  
         [0068]     Upstream of the closure, the machines comprise bag forming means known per se.  
         [0069]     The filling of the bag with the product can be carried out on the bag manufacturing site. It can for example be carried out before the fixing of the closure assembly.  
         [0070]     Where the filling is carried out after the fixing of the assembly to the mouth of the bag on the same site or on another site, subsequently, it is then possible to provide means for welding the fixing assemblies to the wall of the bag without the formation of the tamper-evident closure.  
         [0071]     Thus the filling can take place through the internal space between the fixing sheets.  
         [0072]     These means can comprise for example means which are interposed between the internal parts of the fixing sheets during the welding step. According to a variant depicted in  FIG. 5 , welding strips  11  and  13  are applied only to the external faces of the parts  61   a  and  61   b . Thus, initially, only the external parts are welded. The formation of the tamper-evident part will be effected by welding the parts  62   a  and  62   b  after the filling of the bag.  
         [0073]     The filling of the bag can take place according to other variants. It is possible for example to fix a fixing sheet to an internal face of one of the walls of the bag, the tamper-evident element being already formed, to carry out the filling of the bag, and then to fix the other sheet to the other wall.  
         [0074]     Thus the filling can take place through the outside, namely between a wall of a bag and a fixing sheet.  
         [0075]     The filling can also be effected through the end of the bag opposite to the mouth where the closure assembly is fixed.  
         [0076]     The fixing machine can comprise means for carrying out welding of the “hot melt” type. It can also comprise adhesive bonding jaws.  
         [0077]     It should be stated that the above description in no way presupposes the position of the machine. For example, it can be a case of a vertical or horizontal movement and the fixing of the closure assembly can take place longitudinally or transversely to the movement of the packaging foil.