Binding element
BACKGROUND OF THE INVENTION 
     The present invention relates to a binding element, more specifically to a binding element of the type of which the inside of the back is provided with an amount of glue which melts under the influence of heat. 
     Binding elements of the above-mentioned type are widely known. In order to bind a bundle of sheets or documents by means of such binding element, the sheets are placed in contact with the glue in the binding element. Consecutively, the whole is placed vertically, the back facing down, on a heating element, so that the glue melts and the sheets intrude in the glue layer. After the binding element has been taken off the heating element, the glue hardens, with as a result that the sheets are retained in the binding element by means of the glue. 
     In order to obtain that the heat of the heating element is fed to the glue in an efficient way, more specifically is spread very equally, it is also known to apply an element of a heat conducting material, such as metal, in the back. 
     It is also known that the above-mentioned element can consist of a metal U-shaped profile. An example thereof is disclosed in GB 2.197.156. The use of such U-shaped profile also offers the advantage that, when laying the bound bundle open, respectively turning the pages thereof, the glue connections between the sheets, as well as the glue connections between the sheets themselves, is burdened little or not at all, thus avoiding that the sheets come loose. 
     According to GB 2.197.156, the U-shaped profile is located at the inside of the file. The binding element therefore has the disadvantage that it is very user-unfriendly, as it is very difficult to slide all sheets into the U-shaped profile, especially with thick bundles. Indeed, the outer sheets end up on the edge of the relatively thick metal profile. 
     SUMMARY OF THE INVENTION 
     The invention therefore aims at a binding element whereby the above-mentioned disadvantage is excluded, and more specifically at a binding element whereby said heat conducting element, whether this has a U-shaped section or not, does not trouble when inserting a bundle of loose documents in this binding element. 
     To this end, the invention relates to a binding element, consisting of an actual file which is made of one or more parts, the back of which contains an element in a hard heat conducting material, and whereby the back is provided at its inside with an amount of glue which melts under the influence of heat, characterized in that the file, at least partially, is adjacent to the inside of said element. As the file is at least partially adjacent to the inside of the heat conducting element, loose sheets which are inserted in the file can slide into the right position in an unhindered way. 
     Indeed, in case a U-shaped heat conducting element is used, the sheets to be bound are lead as far as next to the upright walls of the U-shaped element. 
     In case a flat heal conducting element is used, it is excluded that the outer sheets end up next to the heat conducting element. 
     The portions of the file adjacent to the inside of the heat conducting element are preferably glued to the latter, for instance with a once-only activatable glue. This is especially important when a continuous inner cover is applied against the heat conducting element, as such glued connection ensures that the inner cover is always in perfect contact with the heat conducting element, and thus the glue for binding the documents is also in perfect contact with the heat conducting element. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to better illustrate the characteristics according to the invention, some preferred embodiments are described hereafter, as examples with no limiting character whatsoever, reference being made to the accompanying drawings, in which: 
     FIG. 1 represents a cross-section of a binding element according to the invention; 
     FIG. 2 represents the part marked with F2 in FIG. 1, of an enlarged scale; 
     FIG. 3 represents the binding element of FIG. 1 during use; 
     FIGS. 4 to 7 represent four variants of binding elements according to the invention; 
     FIG. 8 represents a part of the binding element of FIG. 7 in opened position; 
     FIGS. 9 to 12 represents four more variants of binding elements according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As represented in FIG. 1, the invention relates to a binding element 1, consisting of, on the one hand, an actual file 2 which is composed of one or more parts, and provided at the inside of its back 3 with an amount of glue 4 which melts under influence of heat, and on the other hand, an element 5 in a hard and heat conducting material, applied at the back 3. 
     The particularity of the invention exists in that the file 2, at least partially, thus with a number of components parts thereof, is adjacent to the inside 6 of said element 5. 
     This characteristic can be realized in different ways. To this end, in the embodiment of FIG. 1, the file 2 is formed of one continuous sheet of paper, synthetic material or the like which is attached to the inside 6 of the element 5. Thus the sheet forms a front sheet 7, a back portion 8 and rear sheet 9. Said glue 4 consists of a strip of hardened adhesive which is applied to the inside of the back portion 8. 
     According to FIG. 1, the element 5 consists of a U-shaped profile with rectangular section, formed of a back wall 10 and two side walls I! and 12. 
     Preferably, the file 2 fits tightly against the inside 6 of the element 5, or at least fits tightly against the back wall 10 of the element 5, so that the heat transfer W of the element 5 to the glue 4 is optimal and for example not hindered by air inclusions or the like. Preferably, the portions of the file 2 adjacent to the inside 6 are therefore, with their entire surface or not, adhered to the latter, as is represented in the detail view of FIG. 2. To this end, use can be made of a thin layer of glue 13. The glue is of such a kind that it will not come loose during the heating when binding documents. To this end, use can be made of a thermo-activatable glue, the melting temperature of which is considerably higher than the binding temperature, a once-only thermo-activatable glue or a non-thermic glue. 
     As is represented further in FIGS. 1 and 2, openings 14 can be applied in the portions of the file 2 adjacent to the inside 6, which allow a bulge 15 of the glue, thus causing that a better adhesion is obtained, especially around the edges 16 of the openings 14. 
     It is to be noted that instead of a connection by means of the glue 13, according to an embodiment not represented in the figures, the portions of the file 2 adjacent to the inside 6 of the element 5 can also be clenched in the latter. 
     FIG. 3 represents the use of the binding element 1 of FIG. 1. During the binding, the binding element 1 is placed on a heating element 18, together with the documents 17 to be bound. Hereby, the glue 4 melts and the documents 17 intrude at their bottom edges in the glue 4. After the whole has hardened again, the documents 17 are secured in the binding element 1. 
     It is clear that, during the insertion in the binding element 1, the documents 17 can easily glide according to arrows A between the side walls 11 and 12 of the U-shaped element 5, respectively can be tapped between them, thanks to the fact that the file 2 is adjacent to the inside of the element 5. Indeed, the documents 17 cannot end up on the relatively wide edges 19 and 20 of the element 5. 
     In FIG. 4 a variant is represented whereby the front sheet 7 and the rear sheet 9 of the file 2 consist of separate sheets which are both attached to the inside 6 of the respective side walls 11 and 12, preferably by means of glueing. The sheets 7 and 9 can hereby also be provided with openings 14 as described above. 
     According to the embodiment of FIG. 4, the glue 4 can be directly applied to the element 5. 
     As represented in FIGS. 5 and 6, the element 5 can be provided with a covering 21, for example a material with an elegant aspect, for example printed paper. The covering 21 is preferably folded over the edges of the element 5, whereby the folded parts 22 and 23 are located between the side walls 11 and 12 and the front sheet 7 and the rear sheet 9. 
     It is to be noted that in FIG. 5 an embodiment is represented whereby the front sheet 7, the back portion 8 and the rear sheet 9 are made of one sheet, while FIG. 6 represents an embodiment whereby use is made of a separate front sheet 7, rear sheet 9 and a connection strip 24 which is adjacent to the element 5, respectively to the folded parts 22 and 23. The sheets 7 and 9 are hereby only attached to the connection strip 24, preferably by means of glueing. The build-up of FIG. 6 is of course also possible without the covering 21 being present. 
     The build-up with the connection strip 24 is especially suitable in case that is opted for a front sheet 7 and/or rear sheet 9 of a relatively stiff material, for example transparent synthetic foil. The connection strip 24 can than be made of a more supple material than the front sheet 7 and the rear sheet 9, so that the folding open of the binding element 1, despite the use of a front sheet 7 and/or rear sheet 9 of a relatively stiff material, is not hindered. 
     According to the embodiment in FIG. 7 the front sheet 7 and rear sheet 9 both consist of a cardboard plate. At the inside a connection strip 24 is applied, for example made of paper, which is adjacent to the inside of the element 5, and is preferably glued to the latter. 
     The whole is covered with an outer cover 25, preferably with an elegant aspect, for example of printed or coloured paper, with or without relief. The outer covering 25 can be folded at all edges of the binding element 1. 
     As is further represented in FIG. 7, the front sheet 7 and the rear sheet 9 are attached at a certain distance D from the element 5, so that folding zones 26 are formed, which allows the binding element 1 to be folded open as represented in FIG. 8. These folding zones 26 are also indicated in FIG. 6. 
     As represented in FIG. 8, openings 27 can be applied in the material of the file 2 that is adjacent to the inside 6 of the element 5, which allow the direct heat transfer from the heat conducting element 5 to the glue 4. Preferably, these openings 27 exist in a continuous perforation over the entire back. According to a variant, which is not represented, one long continuous excision can be provided. 
     In FIG. 9, a variant of FIG. 7 is represented, whereby the connection strip 24 forms part of a continuous inner covering 28. 
     FIGS. 10 and 11 represent two further variants whereby the glue 4 is in direct contact with the element 5. 
     FIG. 12 represents a variant whereby the heat conducting element 5 consists of a flat strip. As the file 2 is hereby adjacent to the inside 6 of the element 5, with which is meant the side directed towards the inside of the binding element 1, it is excluded that documents 17 which are inserted in the binding element 1 end up next to the element 5. It is clear that also in this case the file 2 can be assembled in different forms. The example of FIG. 12, in which the actual file 2 consists of a front sheet 7, a back portion 8 and a rear sheet 9 which are made of one single sheet of paper, synthetic material or the like, and a covering strip 19 which is applied to the outside of the element 5, is therefore in no way limitative. 
     In the above-described embodiments, the element 5 is preferably made of metal and in the most preferred embodiment of steel. It is to be understood that by the above-mentioned expression &#34;hard material&#34; is meant that the element 5 is made of a material which is little or not bendable and is certainly less bendable than paper or synthetic foil. 
     It is clear that the different characteristics of different embodiments can be mutually combined. 
     The present invention is in no way limited to the embodiments described above and represented in the drawings, but such binding element can be realized in different forms and dimensions without leaving the scope of the invention as defined in the enclosed claims.