Universal paper file with inside glued back for bundling documents

Abstract: Universal paper file with inside glued back for bundling documents, of the type consisting of a front cover, a back cover and a back, which at the inside contains a glue layer made of a sort of thermosetting glue, characterized thereby that both the glue of said glue layer and the back of the paper file are made of materials that upon thermal activation enter into a chemical reaction, which provides a mutual per manent bond.

Description: The present invention relates to a universal paper file with inside glued back for bundling documents, comprising a front cover, a back cover and a back of PVC, which at the inside contains a glue layer made of a sort of thermosetting glue. Paper files for binding documents, wherein a layer of glue is provided at the inside of the back, are known in various variants and embodiments e.g. from FR-A-2 189 215 and BE-A-869 886. According to those patents the back provided with the glue is placed against the documents, after which the glue is heated, whereby the glue forms a proper adhesion with the documents. The file itself is manufactured by covering the back with a strip of the glue which is fixed to the back by heating. BE-A-869 886 discloses a back of PVC but does not disclose any example of glue, while FR-A-2 189 215 discloses a glue comprising an ethylene-vinylacetate copolymer resulting in a physical bond of the glue with the back. The above mentioned known files, however, have the disadvantage that they become loose, especially after some time, although the proper bundle of documents remains adhered. In varying climatic conditions as well as by phenomena of fatigue and ageing, the quality of the adhesion of the glue layer to the inside of the back is impaired after some time. Gluing together PVC and paper by thermosetting epoxy glue is disclosed in DE-A-1 569 985. This patent application does hoewever not relate to paper files with inside glued back for bundling documents. Thus it is an object of the present invention to provide a universal paper file with an inside glue layer for thermosetting glue systems, wherein by using said paper file the above disadvantage is excluded systematically, in other words, wherein a permanent adhesion between the glue layer and the inside of the back is realized. For that purpose, the glue of said glue layer is made of a material that, upon thermal activation, enters into chemical reaction with the back of PVC, said material comprising hydrogen, forming upon the thermal activation a chemical bond with the chlorine of the PVC. Upon composing universal paper files of that kind, the glue layer is applied to the inside of the back in a conventional way. At normal temperature, no chemical bond forms between this glue layer and the material of the back, in other words the glue layer co-operates with the back by its normal adhesive power. When a paper file is applied around a bundle of documents, the back and its immediate surroundings are heated by means of apparatus known by themselves. By selecting the glue at the one hand, and of the material of the back at the other hand it is now achieved according to the invention that during the thermal activation a chemical reaction takes place and a bond forms between both materials, which ultimately provides a permanent bond between the glue layer and the back. The bond between the glue layer and the bundle of documents occurs in the normal way through the adhesive power of the glue. As a back is used for a paper file made of PVC, a glue will be employed forming a hydrogen bond with the chlorine of the PVC. The present invention is by no means limited to the embodiment described as an example, but suchlike universal paper file with inside glued back for bundling documents, and more especially the selection of the glue at the one hand and of the material of the back at the other hand may consist in distinct variants without departing from the scope of the present invention as defined in the claim.

Claims: Universal paper file with inside glued back for bundling documents, comprising a front cover, a back cover and a back of PVC, which at the inside contains a glue layer made of a sort of thermosetting glue, characterized in that the glue of said glue layer is made of a material that, upon thermal activation, enters into chemical reaction with the back of PVC, said material comprising hydrogen forming upon the thermal activation a chemical bond with the chlorine of the PVC.

Inventors: MUGNAI GUIDO, MUGNAI, GUIDO
Applicants: UNIBIND CYPRUS LTD, UNIBIND (CYPRUS) LIMITED
Application year: 1987
Main classification: B42D3
IPC codes: B42D1, B42F7, B42D3, B42C9