PUR binding (or polyurethane reactive binding) is considered to be superior than perfect binding though both the processes are essentially same. In both the cases loose pages are adhered together in their spine with adhesive. In perfect binding the adhesive used is however ethylene vinyl acetate or EVA adhesives and PUR adhesives are considered to be superior. Therefore, naturally book printing units are preferring PUR over EVA to provide a better quality to their buyers. The books that have PUR in their spine can be kept open completely flat without damaging the book and without having leaves coming out from all over the places.
Book printing trade has changed greatly over last few years with sophisticated machines, completely automated operations and better printing and binding techniques. All the book printers now use printing machines that are computer controlled and you may find people operating such huge machines in spotless white uniform that was a dream few years back. The stain and stigma from the book trade has gone and binding process has also evolved to keep pace with other areas of developments. PUR binding in one such example.
People used to buy hard bound or case bound books even if they were much costlier than their poor cousin ‘paperback’ versions because of the quality of binding. Though perfect binding made the book binding process quite simple and provided a cost advantage for the producers as well as the buyers, they were avoided by many because of the quality they offered. After one or two casual handling one would find pages coming out off the spine making the book completely useless or a hassle to manage. PUR binding improved the situation to a great extent and book printing presses quickly shifted to this process.
PUR binding also uses smaller amounts of adhesive than perfect binding. So, one can have a square spine for a very thin book as well. Book printing is moving toward self publication and short-run book printing services and for them PUR has become the obvious choice. Again, PUR glue is far better than EVA in terms of durability and flexibility and it sets quicker than EVA glue. So, once the adhesive is cured or set it is also impossible to take out a leaf out of its spine. Another factor that goes in favour of PUR is the adhesion strength it presents even for UV-coated or lacquered pages. And, they prove to be equally good for clay-coated papers.
PUR binding adhesive penetrates to a greater depth and provides better bonding. The lie flat handling has made it indispensible for books offering hands-free reading. Book printing presses therefore consider this form of binding to be more acceptable for their readers. PUR has also been accepted as the best adhesive for Otabind-style of binding and therefore used by more and more book binders. The adhesive supports a temperature range of over 200°F or below -40°F without causing any rupture in the film and therefore presenting more strength. Obviously, there are more advantages in using PUR than other conventional processes of binding.