Лако-красочные материалы — производство

Fold gluing is an additional processing step that can be performed at the same time as the folding process itself. A glue line is applied to the fold line via nozzles on the sheet in the sheet folder or on the paper web in the rotary offset printing press in such a way that, after the folding process, the leaves of the sheet are joined with each other in the gutter. Folded sheets, for example flysheets or inserts, are manufactured in this way. Fold-glued sheets can be bound to blocks following compiling, without the need for unsewn spine binding, and this provides for a very high stability. Fold gluing is also used for the manufacture of brochure or flysheet pockets, for envelopes or lottery tickets, or during paper lamination in the production of postcards. The benefits of fold-glued sheets are manifold. First, they are less bulky in the fold than saddle-back — stitched brochures, and trimming, stacking and packaging is easier. Second, their manufacture is more economical. For fold gluing, either plasticized polyvinyl acetate homopolymer or EVA copolymer-based dispersion adhesives are used. A proximity sensor and a control unit activate the fold gluing aggregate that applies a glue line (the length and width of which is accurately positioned) to the sheet. The first-generation fold gluers were contact systems, but since the early 1990s the adhesive has been applied via electric noncontact nozzles that provide for an airtight closure during machine stoppages. As with an inkjet printer, glue dots are applied at a rate of600 or 1000 per second. Multirow applicators are available for special applications, such as the closure of pockets.

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