The book binding process relies heavily on graphic arts adhesive solutions to produce quality bound books. Without good adhesion, individual pages or larger sections of pages may detach from the binding. These quality issues can be detrimental to a printer or publisher brand.
Types of Binding
While most binding operations rely on adhesives, there are multiple types of binding methods to choose from. The most common adhesive-related binding methods include:
Perfect binding is one of the most common methods for binding books, though the term “perfect” actually refers to the cut of the pages rather than the binding. Perfect bound books—more commonly known as softcover books or paperback books—are bound via thermal glue. This strong, flexible glue holds the pages and the cover of a book together. In order to achieve the smooth edges that consumers expect when they purchase a book, the three non-bound sides of the book are trimmed after binding.
Usually, perfect bound books feature card-stock covers that are laminated or otherwise coated for protection. Perfect bound books offer a quality visual appeal while providing an affordable method for binding.
PUR binding is a form of perfect binding. The primary factor that differentiating PUR binding from other perfect binding processes lies in the adhesive. PUR binding uses a polyurethane reactive (PUR) adhesive. This adhesive is more powerful than the standard thermal adhesives used in general perfect binding and renders books more durable. PUR bound books are flexible and exceptionally resistant to page pull out.
Layflat binding is another variation on perfect binding. As the name suggests, this method creates finished books that can be laid flat while they are open. The square bindings associated with perfect bound books don’t provide this degree of flexibility. Layflat bound book covers are only glued to the sides of their spines. Layflat binding allows a book’s spine to float above its cover while opened.
This method is ideal for journals and notebooks that are meant to be written in, as well as textbooks or other reference books that may need to lie open for frequent consultations.
Graphic Arts Case Binding Adhesives
Case bound books are more commonly known as hardcover books. The process of binding these books is different from those used to bind paperbacks. First, a book’s pages must be arranged into signatures. The pages are then stitched or sewn together in the proper order. Glued-on endpapers attach these pages to the book’s cover. Covers may be made of vinyl, cloth, leather over cardboard, or other materials.
Graphic Arts Tipping Adhesives
Adhesive products play a crucial role in the book binding process. Beyond traditional binding, adhesives are also central to a process known as tipping. Tipped-in pages and illustrated plates—sometimes called paste-ins—get printed separately from a book’s main text. The tipped-in pages are then glued to bound pages in order to attach them to the books.
Graphic Arts For Retail And POP Displays
Retail and point-of-purchase displays for books also require high-quality adhesive products. Pre-adhered tape constructions are central to bonding processes that hold displays like these together. High-quality adhesive products allow merchandising experts to forego fasteners, which helps save time and money.
Other Products For Graphic Arts Adhesives Include:
- Pocket folders
- Folding cartons
- Paper converting
Graphic Arts Adhesives From BC Adhesives
BC Adhesives offers a variety of quality adhesives for use in book binding, retail, and other publishing-related applications. For more information about our products or capabilities, please contact us.
Check out the news article below for more information about BC Adhesives’ solutions for graphic arts and publishing customers.
RELATED ARTICLE FEATURED IN POSTPRESS MAGAZINE
PUR or EVA – What is the Best Adhesive Option? – Article Featured in PostPress Magazine
By Matt Cassidy
Information provided by Duplo USA Corporation and BC Adhesives</5>
It can be tough for binderies to decide which adhesive to use in their manufacturing process. The industry seems to be very comfortable with ethylene-vinyl acetate (EVA) since it’s been around for so long, but as polyurethane reactive (PUR) becomes more popular, it is important to know the differences between the two. Each has different qualities that might make it the correct option for different types of books.
PUR adhesive has many advantages and is becoming more common among customers as a requirement to be used on their books. PUR can bind varnished, UV-coated, carton, mylar and other difficult stocks, where EVA adhesive may struggle with certain coatings or substrates. PUR also is a great choice for digital printing because this type of adhesive isn’t affected by ink migration. It is also a great option for tough papers, cross-grained stocks and higher basis weight recycled papers.
Difficult substrates aren’t the only reason to use PUR: It makes for a higher quality book with excellent flexibility and lay-flat qualities, especially for larger books. Page pulls are usually 40 to 60% higher than when using EVA. And, for most applications, less PUR adhesive is needed, which helps decrease the possibility for adhesive to creep out during the nipping process.
Be cautious when opting for the PUR route, because equipment is going to be more costly and require more maintenance. Since PUR cures when it comes into contact with air, the system needs to be sealed every night. That can be done by applying grease to the nozzle and pot. Failure to complete this step could lead to curing throughout the system.
Another concern with PUR is the MDI (diphenylmethane diisocyanate) emitted during the curing process. This can be emitted as vapor or aerosol and can cause allergic reactions to the skin or respiratory issues. MDI levels drop drastically once substrates are joined, so this is mainly a concern during preventive maintenance. There are tools to test the MDI levels in a facility. These levels can be lowered with venting and other techniques. Finally, the curing time for PUR is much longer than for EVA; it is common for binderies to wait a full 24 hours before shipping finished books.
EVA is a great option for more standard operations. The handling of this adhesive, along with maintaining the system, is much easier than with PUR. Binderies can move much faster when using this product due to the fast curing time. EVA has very quick set points that allow for a short cure time, meaning faster turnaround for trimming and the finished piece.
EVA also is a much more cost-effective option for both the equipment and the adhesive itself. Milling is still extremely important when using EVA, but it’s not as much of a factor as when using PUR. Binders using EVA can notch bind their books. This means that small notches are cut into the spine and filled with glue before the cover is applied. This is not recommended for PUR applications. PUR needs the peaks and valleys of the fibers across the entire spine to succeed. Overall, EVA hotmelt glues still have their place in book-binding – especially when binding thread-sewn books – as the thicker glue allows for greater penetration into the spine area of the folded sections.
In summary, both processes are still widely used within print finishing and bindery operations. The question of “which is best?” needs to be replaced with the question “which is most suitable?” The decision to use one over the other is job-specific and involves numerous considerations – from substrate used and thickness of the book, to the intended use of the product and financial constraints to produce.
PostPress would like to thank Duplo USA Corporation (www.duplousa.com) and BC Adhesives (www.bcadhesives.com) for their assistance with this article.
Which One is Most Suitable?
Advantages of PUR adhesives
- Aggressive adhesive for coatings, digitally printed stocks, other tough surfaces
- Isn’t affected by ink migration
- Excellent flexibility and better lay-flat qualities
- Use less adhesive – less likely for adhesive to “creep”
Advantages of EVA adhesives
- Runs on less costly machinery and less maintenance on machinery
- No concerns with the MDI (diphenylmethane diisocyanate) emittance
- Much shorter curing time for faster turnarounds
- Less costly adhesive and best choice for many standard applications