New Adventures in Adhesives
I have a son who’s heading towards a degree in organic chemistry. This gives me great hope, since as I learn more about book binding, I discover that it’s more about chemistry than anything else. Given book binding’s long and glorious history, one would think that the adhesives used have been pretty well defined. Not true, it turns out.
With the advent of digital printing, a whole new set of challenges have been thrown at the folks in the bindery. And much of the problem solving has been taken on by the adhesive manufacturers.
The last great leap forward was the introduction of PUR (polyurethane reactive) adhesives, which bonded with paper via a cross-linking chemical reaction between the glue and the moisture content contained in the paper. PUR solved many problems associated with digitally printed papers that are coated with fusing oils and toners. It established an extremely strong bond with stocks that could not be bound with conventional hot-melt glues.
But that is not the end of the tale, and adhesive research continues. New and promising hybrid glues are on the horizon. Further development of EVA hot-melt technology marches on, with newer hot-melts adhesives claiming to offer superior bonding ability.
Hot-melt manufacturers are improving their products’ capabilities with regard to digital print issues. Lower application temperatures (lower temperatures are better for the equipment), and improved formulations can now support digitally printed sheets that were not possible to handle a few years ago.
In the realm of the more exotic, there have been continuing developments with cold glues. A small German manufacturer, in cooperation with a major chemical company, has been developing a completely cold, styrene-based adhesive that will bond to almost any substrate.
It’s a two-step process in which a liquid protein is applied to the book block (which has been prepared with a special spine prep process), and then followed by a cold glue. The appeal of this is obvious—no heating time, no adhesive fumes, and minimal cleanup since this adhesive is applied with a nozzle.