BACKGROUND OF THE INVENTION Printed pages may be bound into a book using various methods, for example, using a hot-melt adhesive. In this method, a hot-melt adhesive may be applied to an inner surface of a central portion of a cover or to a spine of a book block. The cover may then be positioned such that the timer surface of its central portion abuts the spine. Heat and pressure may be applied to the contact area to cause the cover and the spine to adhere.

When heat is applied to me hot-melt adhesive, the substance changes fi-om a high to a low viscous state. When the adhesive is in the low viscous state, pressure may be applied to the spine area causing the adhesive to spread out over the desired location, adhering to the pages and cover. Once the adhesive has cooled, the adhesive returns to its original high viscous state.

If the adhesive is not sufficiently heated, the viscosity does not become low enough, and the adhesive may not spread between the pages. On the other hand, if the adhesive is over heated, the viscosity of me adhesive may become too low, and the adhesive may run off into undesired locations.

BRIEF DESCRIPTION OF THE DRAWINGS The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which : Fig. 1 is a schematic illustration of a hot-melt adhesive tape according to some embodiments of the present invention ; and Fig. 2 is a schematic illustration of the adhesive tape of Fig. 1 as utilized to bind a book according to some embodiments of the present invention.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Some embodiments of the present invention are directed to a method for boolcbinding. A hot-melt adhesive tape having layers with different viscous properties in the melted state is used. The tape may be positioned between a spine of a book block and an inner surface of a central portion of a book cover such that a layer having a high-viscosity hot-melt adhesive substance may be positioned next to the cover and a layer having a low-viscosity hot-melt adhesive may be positioned next to the spine.

Reference is now made to Fig. 1, which is a schematic illustration of a hot-melt adhesive tape according to some embodiments of the present invention. In the exemplary configuration, shown in Fig. 1, a hot-melt adhesive tape 2 may comprise a first adhesive layer 10 and a second adhesive layer 12. The widths of layers 10 and 12 may vary according to the application's requirements. However, it should be noted that tape 2 may have a different configuration, such as, for example, having at least another adhesive or non-adhesive layer in between layers 10 and 12.

Adhesive layer 10 may comprise a high-viscosity hot-melt adhesive substance.

Adhesive layer 12 may comprise a low-viscosity hot-melt adhesive substance. When heated to a high temperature, such as, for example, between 80°C and 200°C, the viscosity of the adhesive substance of layer 10 may be, for example, 5000 CPS. When heated to a high temperature, such as, for example, between 80°C and 200°C the viscosity of the adhesive

substance of layer 12 may be, for example, 1900-2250 CPS. At room temperature, the viscosity of the adhesive substances of both layers may be similar. In some alternative embodiments, the viscosity of the adhesive substance of layer 10 may be different from that of layer 12 also at room temperature.

When the high-viscosity hot-melt adhesive substance is heated, it remains highly viscous and therefore practically immobile in comparison to a low-viscosity hot-melt adhesive substance mat when heated becomes fluid and tends to flow.

The low-viscosity adhesive substance may be selected according to desired properties, such as, for example, viscosity, penetration properties, wetting properties, binding temperature and speed. Typically, tape 2 may be in a form of a roll (not shown) having a width that is generally equal to the length of me pages of a book block being bound. Tape 2 is cut to a desired size at the time of use. Generally, the size to which tape 2 is cut when binding is substantially equal to the width of the spine of the book block.

This is especially useful in a book machine or other made-to-order priiitiiig/binding machine by which the pages are printed and/or collated at a store or an office location. In such a situation, once the pages are collated and the eventual width of the stack is known, the strip of adhesive tape 2 is then cut to the appropriate width. An example of such a machine is described in WO 01/56794 to the common assignee.

Reference is now made to Fig. 2, which is a schematic illustration of a book having a hot-melt adhesive tape according to some embodiments of the present invention. An exemplary book 6, having a plurality of pages 18 aligned into a book block having a spine 20 and a cover having a central portion 16, is described. A strip 4 of hot-melt adhesive tape 2. described hereinabove with respect to Fig. 1, may be placed between an inner surface of central portion 16 and spine 20 causing them to adhere.

By using different viscosity layers, adhesive strip 4 may enable adhesion to both the cover and the pages such that layer 10, being of higher viscosity when heated, may adhere to central portion 16 of the cover book without leakage. The adhesive substance of layer 12, being of lower viscosity than that of layer 10 when heated may spread into the pages to afford adequate adhesion.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.