This invention relates to a universal binding element for binding loose documents in a file.

More especially the present invention relates to a binding element of the type that allows that, on the one hand, a bundle of loose documents are brought together by this on one side and, on the other hand, the unit that is formed by the binding element and the bundle of bound documents is attached in a suitable existing file of any material, whereby use is made of a layer of glue meltable under the influence of heat at least for joining the loose documents.

Files which are provided with a supple spine on which a layer of glue meltable under the influence of heat is applied on the inside are already known, for example as described in the Belgian patent no. 869.886. These files are intended as outer covers, through which the utilisation of them then also remains exclusively limited to the use of always the same binder.

In order to be able to apply thermal binding systems more universally, binding elements of the already mentioned type were then also developed, in other words which allow

3. bundle of documents to be bound and which at the same time provide a simple attachment of such binding element in any type of binder of file, whether of paper, cardboard, plastic, leather or similar.

3indinα elements of this type are described in the Belgian patent applications no. 8701029 and no. 8800689.

According to the Belgian patent no. 8701029 use is made of a binding element that principally consists of a spine on which a layer of glue meltable under the influence of heat is applied on the inside and a flap provided along at least one side of the spine which comes sideways along the bundle of documents when binding and which is provided with a double sided strip of adhesive tape on its outside. The loose documents are bound in a thermal manner, while the attachment of the formed bundle to the outer cover is effected by means of the double adhesive tape, which provides for the attachment between the back of the bound bundle of documents and the back sheet of the outer cover.

Notwithstanding this binding system is very economical in certain applications, its utilisation is rather difficult because two attaching systems are applied, on the one hand, the melting glue and, on the other hand, the double sided adhesive tape. Furthermore the binding element according to the Belgian patent no. 8701029 is only applicable there where the bundle of documents may be attached to the back sheet of the outer cover and whereby the direct attachment of the bundle to the spine of the outer cover is not desired.

From the Belgian patent application no. 8800689 a binding element is known that consists of a sheet of relatively stiff material and a strip of glue applied over the length of one edge of this sheet which extends past the sheet. The bundle of documents to be bound, the binding element and an outer cover are hereby brought together in the thermal binding device, after which simultaneously.

through the melting of the glue, on the one iiand, the loose documents are bound together and, on the other hand, these documents are attached directly- to the ≤pine of the outer cover.

Notwithstanding the good results which can also be achieved with the binding element according to the BE 8800689, such binding element shows the difficulty that when installing the unit in the heating apparatus the somewhat protruding strip of glue is sometimes difficult to position, whereby this strip can become folded double under the bundle of loose documents, through which this is only partly bound.

Likewise according to the Belgian patent application no. 8800689 the strip of glue overlaps against the outside of the aforementioned sheet, in other words the side which is directed away from the bundle of documents. With the installation of the outer cover and the melting together of the unit the attachment arises not only between the spine of the bundle of documents and the spine of the outer cover, but also partly between the front sheet of the bundle and the front sheet of the outer cover, which can be undesirable for certain applications. When this binding element is applied by inexperienced people who do not sufficiently press the front and back sheets of the bundle, it can also occur, that these front and back sheets do not come into contact with the glue.

The present invention relates to a universal binding element that does not show the aforementioned and other inconveniences when using it and that allows that through one thermal treatment simultaneously, on the one hand, the loose documents are mutually attached and, on the other hand, the bundle of documents are attached to the spine of the outer cover, all of which such that a particularly good binding can also be achieved for the front and back sheets of the loose documents and a very local attachment to the spine of an outer cover.

For this purpose the invention concerns a universal binding element, for binding loose documents in a file, vith as characteristic that it principally consists in an inner cover formed of a first part that is intended for forming a front sheet; a second part that is intended for forming a back sheet, and a third part that is intended for forming a spine, which includes adhesive means which are mainly formed of glue meltable under the influence of heat and which, when heated and subsequently cooled off, provide an adhesive connection on both the inside and the outside of the formed spine.

In jrder to show better, the characteristics according to the present invention, some preferred embodiments are described hereafter, as examples and without any restrictive character, with reference to the enclosed drawings, in which:

figure 1 shows a first embodiment variant of the invention; figure 2 shows on a larger scale and in a preformed embodiment the part that is indicated by F2 in figure 1 ; figure 3 shows a bundle of documents which is bound by means of the binding element from figure 2; figure 4 shows the binding element from figure 1 in perspective; figure 5 shows a variant of the binding element according to figure 4; figure 6 shows a second variant of the embodiment of the invention; figure 7 shows on a larger scale a view of the part that is indicated by F7 in figure 6; figure θ shows the application of the binding element according to figure 7.

As shown in the figures the binding element according to the invention principally consists in an inner cover 1 formed out of a first part 2 that is intended for forming

a front sheet; a second part 2 that is intended for forming a back sheet; and a third part 4 that is intended for forming a spine, which includes adhesive means 5 which can provide for a gluing attachment both on the inside 6 of the formed spine, in other words the side which is directed toward the bundle of documents to be bound, and on the outside 7 of the formed spine, in other words the side which is directed away from the bundle of documents to be bound.

In a first preferable embodiment the aforementioned first, second and third parts, respectively 2-4, principally consist of one continuous sheet 8, of paper, lightweight cardboard or any other material, for example plastic. The adhesive means 5 consist of a first and second amount of glue, respectively 9 and 10, which are applied at the level of the place which is intended to form the spine respectively on both sides of the aforementioned sheet 8.

In order to obtain that, on the one hand, a bundle of documents are effectively glued into place in the binding element I, and, on the other hand, the attachment between the binding element 1 and an outer cover would only be effected locally, the amount of glue 9 applied on the inside 6 is preferably larger than the amount of glue 10 applied on the outside 7. The amounts of glue 9 and 10 are preferably in the form of strips, which extend over the length or almost the complete length of the spine to be formed. As is again shown in figure 1 the strip of glue 9 is preferably wider than the strip of glue 10, all of which such that the glue 9 extends to outside the locations 11 and 12, where the folding edges of the spine will be formed, while the amount of glue 10 is situated inside these locations 11 and 12.

The user friendliness of the product from figure 1 can still be improved by producing it like a preformed cover, as shown in figure 2.

Figure 3 shows the use of the binding element 1 according to figures 1 and 2. The binding element 1 together with the cundle of loose documents 13 inserted in it and an outer cover 14 of any material is hereby placed with the -pine of the unit against the heating plate 15 and between the supports 16 and 17 of a thermal binding apparatus. Through the heat applied the amounts of glue 9 and 10 melt, whereby the glue 9 penetrates between the documents 13 and after cooling off and solidifying provides a solid connection between the bundle of documents 13 and the binding element 1, while the glue 10 melts simultaneously which after cooling off and solidifying provides for the attachment between the binding element 1 and the outer cover of the file 14.

From figure 3 the importance of the width of the strip of glue 9 also appears. Because the glue 9 initially extends past the folding edges of the spine of the binding element 1 , very good attachment now also develops at the locations 18 and 19, in other words between the binding ≥lement 1 and the frontmost, respectively the rearmost document of the bundle of documents 13 , whereby even with some shifting of these sheets the contact with the glue during the melting is ensured. By keeping the amount of glue ^" 0 limited it is obtained that this glue does not spread out much and that a very local attachment is obtained between the binding element 1 and the spine 20 of the outer cover of the file 14, whereby in so doing it is avoided that excess glue reaches the side sheets of the binding element 1 and the outer cover 14. This does not however exclude that in certain applications the strip of glue 10 may be selected wider than the spine of the unit.

The front sheet and the back sheet of the binding element 1 , in other words the aforementioned parts 2 and 3 do not need to cover the complete surface of the bundle of documents 13 to be bound. Figure 4 shows an embodiment whereby this is the case, while figure 5 shows an embodiment whereby the intended front and back sheet of

the binding element only show the form of a strip. It is clear that according to another variant one of the two parts 2 or 3 provide for a sheet that corresponds with the complete surface of the documents to be bound, while the other part provides for a sheet that only consists of a strip. The fact that at least one of the two parts 2 and 3 consists of a sheet that covers the complete surface of the bundle of documents 13 to be bound offers the advantage that the adhesive means 5 can more easily be positioned during the binding, thus when the unit is placed in the thermal binding apparatus. In order to facilitate this positioning still further, a complete sheet is preferably applied that, as described in the Belgian patent application no. 8800690 of Applicant, consists of a relatively stiff material not meltable under the influence of heat.

In a second embodiment, according to figure 6, the first part 2 and the second part 3 each consist of a separate sheet 21 and 22, whereby these sheets may or may not correspond with the complete surface of the documents to be bound, while the third part 4 solely consists of the aforementioned adhesive means 5 which in the form of a solidified layer of glue 23 form an attachment between the two sheets 21 and 22. The layer of glue 23 is preferably melted into place overlapping on the sheets 21 and 22 along the side 6 which is intended to form the inside of the binding element 1. The sheets 21 and 22 preferably consist of paper or a lightweight cardboard. It is however clear that other materials such as plastic can also be applied.

As shown in figure 7 the layer of glue 23 can be provided with at least two indentations 24 extending in the longitudinal direction of the spine, through which the formation of precise, rectilinear folds is facilitated at ambient temperature. The indentations 24 are preferably situated just next to the edges 25 and 26 of the sheets 21 and 22.

Figure 3 shows a bundle of documents 13 which is attached in an outer cover 14 by means of the binding element 1 according to figures 6 and 7. It is clear that the glue 23 hereby provides for the direct attachment between the documents 13 and the spine 20 of the outer cover 14.

It is clear that the present invention also relates to the bound bundles of documents which are obtained by means of a binding element 1 according to the present invention.

The present invention is in no way restricted to the embodiments described as examples and shown in the drawings, but such binding element for binding loose documents in a file may be developed in different forms and dimensions without departing from the scope of the present invention.