Abstract:
A bag which includes additional closing profiles which are respectively actuated by a slide during opening and closing. The bag includes a wall portion which forms a veil which can be broken and which is designed in such a way that it covers the slide before the bag is used.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of bags having complementary closure strips actuated both in opening and in closing by a slide. 
     BACKGROUND OF THE INVENTION 
     Such bags are described, for example, in documents EP-A-0 051 010, EP-A-0 102 301, and EP-A-0 479 661. 
     Such bags that are opened and closed by a slide have already given good service. 
     The slides make it easier to open and close the bags. The presence of a slide is particularly appreciated by the elderly or the visually handicapped. 
     Nevertheless, in spite of their advantages, bags with slides are not at present as widespread as expected. 
     The object of the present invention is to improve this field. 
     SUMMARY OF THE INVENTION 
     This object is achieved in the context of the present invention by a bag including complementary closure strips actuated both for opening and for closing by a slide, the bag being characterized by the fact that it includes a portion of the bag wall that forms a web that is suitable for being broken and that is designed to cover the slide before the bag is used. 
     As will be understood on reading the description below, the present invention thus uses simple means to prevent access to the slide so long as the covering web is in place. 
     This avoids any manipulation, whether accidental, innocent, or with criminal intent, particularly on the shelves of large stores. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics, objects, and advantages of the present invention will appear on reading the following detailed description with reference to the accompanying drawing, given by way of non-limiting example and in which: 
     FIG. 1 is a section view through a bag of the invention, during a step of fixing part of the closure strips to the walls of the bag; 
     FIG. 2 is a section view through the same bag, after it has been opened; and 
     FIG. 3 is a view similar to FIG. 1 showing a bag constituting a variant embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a bag  10  made up of two parallel walls  12 ,  14  defining a bag mouth  16 . 
     The general structure of such a bag can be made by numerous dispositions known to the person skilled in the art. 
     Thus, for example, the two walls  12 ,  14  of the bag can be made from a common sheet which is folded in half so as to form two generally parallel flaps corresponding to said walls  12 ,  14  which are fixed together around three sides of their periphery, e.g. by adhesive or by heat-sealing. 
     Under such circumstances, the mouth  16 , which preferably corresponds to a zone in which the two walls  12 ,  14  are joined by adhesive or heat-sealing, can be parallel to and opposite from the fold line in the sheet, or it can be perpendicular to said fold line (in which case the bottom  19  of the bag is likewise formed by sticking or heat-sealing together the two flaps  12 ,  14 , as shown in non-limiting manner in FIG.  1 ). 
     In a variant, the two walls  12 ,  14  can be made from two initially separate sheets that are generally parallel to each other and fixed together around their periphery over four sides, e.g. by adhesive or by heat-sealing, as mentioned above. 
     Bags of the present invention are fixed with complementary closure strips  20 ,  30  that are actuated by a slide  40 . 
     These means can be embodied in numerous ways that are known in themselves. 
     Thus, for example, the complementary closure strips  20 ,  30  can be made respectively of complementary male/female type structures or they can be made of structures comprising complementary hooks. 
     The person skilled in the art knows numerous shapes for complementary closure strips as described in the literature and/or as on sale at present. That is why the shapes of the closure strips  20 ,  30  are not described in greater detail below. 
     The same applies to the slide  40 . 
     It too can be embodied in numerous different ways. 
     In particular, the slide  40  can comply with the dispositions described in document EP-A-0 479 661. 
     That is why the slide  40  is not described in detail below. 
     Nevertheless, it should be observed that the slide  40  is preferably made of plastics material and comprises two side flanges interconnected via a base and co-operating with an elongate central tongue to define two converging passages for the mutually-engageable complementary closure strips  20 ,  30 . Thus, when the travel direction of the slide  40  relative to the closure strip  20 ,  30  tends to move the slide  40  so as to force the closure strips  20 ,  30  into engagement, the bag is closed. When the slide  40  is moved in the opposite direction, the bag is opened. 
     The film(s) constituting the walls  12 ,  14  of the bag can be embodied in numerous ways; The film is preferably made of a plastics material, very preferably of poly-olefin, most advantageously of low or high density poly-ethylene or indeed polypropylene. Nevertheless, the invention is not limited to these particular materials. 
     The invention also applies to bags made of composite material, for example a sheet based on plastic- or metal-coated paper, etc. . . . 
     The complementary strips  20 ,  30  are carried by respective support webs  22 ,  32  fixed to the walls of the bag as described below. 
     In the embodiment shown in accompanying FIG. 1, a first one of the support webs  22  is fixed to the inside surface  13  of a wall  12  at a distance from the line of heat-sealing  17  defining the mouth  16 . In FIG. 1, the connection zone between the support web  22  and the wall  12  is given overall reference  24 . This connection zone can be defined by adhesive or heat-sealing between the inside surface  13  of the wall  12  and the support web  22 . Where appropriate, and as is known to the person skilled in the art, this connection zone  24  can be defined, for example, by heat-sealing ribs that are integrally extruded on the support web  22  and/or the wall  12 . 
     The second support web  32  in the embodiment shown in FIG. 1 is sandwiched between the two walls  12 ,  14  at the mouth  16 , and it is fixed to them at the connection  17 . 
     More precisely, a connection  17   a  is defined between a first face of the support web  32  and the wall  12 , and a second connection  17   b  is defined between the second face of the support web  32  and the second wall  14 . 
     It will be observed, and this constitutes an important advantage of the invention, that the connection defined in this way between the support web  32  and the walls  12 ,  14  can be implemented using conventional heat-sealing jaws of the kind commonly used for closing a bag at its mouth by connecting together the walls  12  and  14  of the bag directly in the conventional manner. Such heat-sealing jaws are referenced  100  and  110  in FIG.  1 . 
     The person skilled in the art will readily understand that the wall portion  12  situated between the connections  24  and  17   a  thus originally covers the slide  40  so as to prevent direct access thereto. 
     However, once this portion of the wall  12  has been broken, the user has free access in conventional manner to the slide  40  both for opening and for closing the bag by separating or interfitting the strips  20 ,  30 . 
     For this purpose, the above-specified portion of the wall  12  can be provided with a line of weakness  11  which extends parallel to the connections  24 ,  17   a  so as to make this portion of the wall easier to open. 
     Furthermore, as shown diagrammatically in FIG. 1, it is preferable for the length L 1  of the above-specified portion of the wall  12  situated between the connection zones  24  and  17   a , i.e. the distance L 1  between the connection zones  24  and  17   a  when the portion of the wall  12  between them is under tension, to be less than the sum of the corresponding lengths L 2  and L 3  of the support webs  22  and  32  situated between the connection zones  24  and  17   a . The person skilled in the art will understand that complying with this geometrical condition facilitates access to the slide  40  and to the strips  20 ,  30  through the opening  11  formed in the portion of the wall  12  situated between the connection zones  24  and  17   a  after said wall portion has been broken. 
     This access is shown diagrammatically in FIG.  2 . 
     The bags shown in FIG. 1 are preferably made on a form, fill, and seal (FFS) type machine, i.e. a machine for performing automatically the operations of forming bags, filling them, and closing them. The general structure of such conventional machines is not described in detail below. 
     Nevertheless, it is recalled that FFS machines generally comprise a forming throat which receives as input the film in the flat state coming from a reel, and which outputs the film shaped into a tube, a filling chute which opens out into the forming neck and consequently into said tube, means for feeding closure strips and for fixing them to the film, longitudinal heat-sealing means for closing the tubes longitudinally, and means suitable for operating sequentially to generate a first transverse line of heat-sealing before content is inserted into the tube via the filling chute, and then a second transverse line of heat-sealing once the content has been inserted into the tube, so as to close a package around the content. 
     In this context of an FFS machine, in the present invention, the support webs  22 ,  32  carrying the closure strips  20 ,  30  and the slide  40  are preferably brought to the film transversely to its travel direction and upstream from the forming neck. More precisely, in this embodiment, the support web  22  is fixed to the film  12  in the connection zone  24  using appropriate means, and in particular heat-sealing jaws, upstream from the forming neck, while the second support web  32  is fixed to the walls  12  and  14  in the connection zone  17  by means of the heat-sealing jaws  100 ,  110  when the above-mentioned “second” line of transverse heat-sealing is made. 
     Nevertheless, the invention is not limited to having the support webs  22 ,  32  disposed transversely to the direction in which the film advances. The invention can equally be applied to feeding the support webs  22 ,  32  together with the closure strips  20 ,  30  and the associated slide  40  longitudinally, i.e. parallel to the direction in which the above-mentioned film advances. Under such circumstances, the support webs  22 ,  32  are fixed on the walls  12 ,  14  not by means of transverse heat-sealing jaws, but by means of longitudinal jaws, i.e. jaws situated parallel to the direction of the forming neck, e.g. the conventional jaws used for longitudinally closing the tube that is obtained at the outlet from the forming neck. 
     It will be observed that in the event of the support webs  22 ,  32  being placed longitudinally, the two connection zones  17 ,  24  can be made simultaneously and not successively as described above when they were put into place transversely respectively upstream and downstream from the forming neck. 
     FIG. 3 shows a variant embodiment in which one of the support webs (in this case referenced  32  and situated adjacent to the mouth  16 ) is itself made up of two segments  32   a ,  32   b , with one of the segments  32   a  situated adjacent to the mouth  16  and fixed to the walls  12 ,  14  in zones  17   a ,  17   b  as described above, while the other segment  32   b  is situated adjacent to the strip  30 , and with the two segments  32   a ,  32   b  forming a dihedral whose concave side is directed towards the outside, i.e. towards the wall  12 . Under such circumstances, the two segments  32   a ,  32   b  can be constituted by elements that are initially separate and that are connected together by adhesive or by heat-sealing at the ridge  33  of the above-specified dihedral or can indeed be constituted by a single element that is folded onto itself via a sharp angle at said ridge  33 . 
     The person skilled in the art will also understand that by using a portion of wall so that it initially covers the slide it is possible to solve in simple manner problems associated with sealing that are generally encountered in bags fitted with slide-actuated closure strips. Naturally, to ensure that bags are sealed sufficiently after the wall  12  has been broken, and after the slide  40  has been manipulated, i.e. after the bag has been opened, the support webs  22 ,  32  and/or the closure strips  20 ,  30  and/or the slide can be provided with numerous dispositions for providing sealing, and in particular those defined by the Applicant in French patent applications FR 98/16236, FR 98/13732, FR 98/13734, and FR 98/05681. 
     Naturally, to ensure that the bag is sealed, it is necessary for the end zones of the support webs  22 ,  32  extending transversely to the connection zones  24 ,  17  also to be sandwiched between the side edges of the walls  12 ,  14  and fixed thereto. 
     Naturally, the present invention is not restricted to the particular embodiments described above, but extends to any variants within the spirit of the invention.