Лако-красочные материалы — производство

A wide variety of adhesives are used in the manufacture of books. Book blocks are provided with endpapers and super cloth (guard or mull strips) bonded to the back of the book block with a 10- to 20-mm flap on both sides, extending over and covering the endpapers. These help to stiffen the joints of the endpapers, thus increasing the form stability ofunsewn-bound, thread-sealed and thread-sewn book blocks. After gluing, for production ofthe book, the blocks are trimmed on three sides. Before casing in the book blocks, they can be rounded and provided with an edge coloring and additional parts (ribbon, head and tail band, inlay and hollow).

Ribbons are inserted to make handling of the books easier; they are bonded to the head of the book blocks or, in the case of brochures, on the last page near the back. Ribbon-inserting machines can be integrated in a book line, inserting the ribbon, for example, in the headbanding machine. When used as stand-alone units, a hot-melt gluing system applies a positionable adhesive line onto the back by means of rollers or nozzles, the latter being very well suited for thin book blocks. The headbands — or rather the head and tail bands — are affixed at the ends of the back of the finished book block. Although, nowadays, their purpose is merely decorative, their role is to hide the hollow spine with its guard, lining material and spine inlay ofthe case. To some extent, a headband helps to stiffen the layers at the upper and lower ends of the back. The purpose of the lining material is to stiffen the back of the book block and to provide a stable and durable form to the back, either rounded or nonrounded. The lining material (i. e. the inlay) is shorter than the height of the book block by few millimeters, and its width goes from one groove to the other (unlike the super cloth, that has two flaps). Lining is a technological prerequisite if the headbands are to be affixed automatically. Lining and affixing of the headbands is performed in a single step. The headband is bonded to the back of the book block in such a way that it spans from the first to the last page, with its roll sitting evenly on the edge. To this end, nozzle­gluing systems apply a small line of dispersion adhesive to the head and end of the previously cut inlay strip that must be absolutely flat in order to make it possible to place it accurately on the back. It must not curl under the influence ofthe adhesive, and must not be stretchable, because otherwise it will not help to stabilize the back.

Furthermore, the lining material must be impervious to the adhesive so as to ensure that it does not adhere to the spine liner of the case during the casing-in process. A mull cloth can be affixed to the back prior to the affixing of the headbands and the inlay strip, although from a technological viewpoint this is only necessary in exceptional cases.

In the industrial bookbinding sector, it is no longer common to use hollows. These are tubes made from thin but very firm paper (kraft sack paper with a density of 50 g m~2), and are mainly used for large-size, heavy products and products with high quality demands (e. g. encyclopedias). They are industrially manufactured by special machines that glue them onto the spine inlay of the case, with the grain orientation in parallel with the book spine. To this end, a dispersion adhesive is applied to the spine liner, and the overlapping side of the hollow is bonded to the inlay and then pressed onto it.