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PUR (polyurethane reactive) Binding Adhesive is the answer for difficult stocks to Perfect Bind. This product has a chemical reaction that occurs during cure time, and it is this elongated cure time which creates a distinct performance advantage in comparison to regular perfect binding glues.
PUR Adhesive is the glue structure used in all of our Lay Flat Bindings, and it’s our “Go-To” glue for difficult projects.
Why use PUR?
PUR is chosen over standard hotmelt adhesives for many reasons, the most important of which is its superior adhesion and the ability of a PUR-bound book to lie flat when open.
Adhesion
PUR is unique in that it will bond to lacquer and UV-cured coatings, films such as Mylar, as well as cross-grained and recycled paper. Due to the polar nature of the polyurethane molecule, these adhesives also bond well to clay-coated papers.
The changes in paper weight, coating and inks used in today's printing applications reportedly pose little challenge for the latest PUR adhesives. The newer PUR products grab and hold heavily coated papers together tenaciously. Page pulls reporedly average up to 40% to 60% better with PUR than with traditional adhesives.
While the migration of inks into a book's gutter can cause binding problems for traditional adhesives, PUR glues remain virtually unaffected by ink migration.
Excellent Lay-flat Qualities
When applied at its recommended thickness - 0.01 inch - PUR is considerably more flexible than standard EVA hotmelts. This ability to lay flat when open allows for hands-free reading. According to National Adhesives, the world's largest software seller as well as a Texas-based computer manufacturer both chose PUR for their instruction manuals several years ago. The firms believed that the lay-flat characteristic was important to their customers.
Books bound by PUR will not fail at extreme temperatures - even over 200° Farenheit, or under -40° Farenheit. These properties were especially important to a binder in Utah who sent books to both the Sahara Desert and to areas in Siberia. According to the binder, customers' adhesive-related complaints were virtually eliminated once the company switched from hotmelt to PUR.
PUR Advantages
- Excellent flexibility and lay-flat qualities
- Ability to withstand temperature extremes, without glue failure
- Bondability to lacquer, UV-cured coated, Mylar and other films
- Binding quality that is unaffected by ink migration into gutter
- 40% - 60% better page pulls than tradional adhesives
- Adheres Cover Stock inserts more securely
- Counters the problems of recycled papers
- Handles cross-grained stocks better
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PUR Perfect Binding
