Binding Solutions, LLC
 
Combination Spine/Hinge Glue System Promises Productivity, Quality Gains
 
An innovative, new three-shot combination spine and hinge glue application system is enjoying early successes at bookbinders in the United States, Europe, Brazil, Japan and Mexico. The TWINFLEX 2000 primer and slot extrusion system offers an attractive alternative to the traditional wheel and glue pot methods for applying the spine and side glue.
 
The slot extrusion technology can bring to bookbinders benefits such as the following:
 
  • One PUR hot melt doubles as the hinge and spine glue
  • Superior layflat
  • No primer penetration between signatures
  • Accurate, controllable thin layer of adhesive film
  • Ink solvent resistance of PUR
  • Excellent book durability; high quality books
  • Recyclability
  • High speed
 
Slot Extrusion
 
The TWINFLEX 2000 3-shot slot extrusion system is applied with a patented primer, pre-primer and PUR hot melt. The pre-primer application prepares the paper surface for the primer by making it more receptive to the primer. The primer then bonds the prepared fibers. After the signatures pass through a short infrared dryer, the slot coater lays down the PUR hot melt, which bonds and reacts with the dried primer. The slot coater head puts down a wide stripe of PUR for the spine glue, which also acts as the hinge glue.
 
The slot extruder consistently meters a precise, thin 0.006-0.0010" PUR film to accurately control adhesive coating weight. This film is one-half to one-third of that deposited with standard EVA hot melts. This means PUR costs are comparable to EVA but with all the benefits of better adhesion and flexibility. The consistent, precise thickness of PUR hot melt also allows bookbinders to accurately calculate and predict spine and hinge adhesive costs.
 
High Productivity
 
The TWINFLEX 2000 system brings high productivity via the Inatec technology and the many benefits of today's PUR hot melts.
 
PUR's high tack allows the system to run at speeds as high as 12,000 books per hour. This is as fast as with any EVA hot melt. Production efficiency and cost savings further result from one PUR hot melt doubling as the hinge and spine glue, eliminating the second side glue and application system.
 
The double-duty PUR hot melt also makes the entire adhesive application recyclable. In contrast to many side glues, PUR is repulpable. Because PUR cross-links and does not remelt, it remains solid and separates readily from the slurry of recycled fiber during the repulping process. Thus, bookbinders can provide books that are readily recyclable to expand their market.
 
Most paper bound by the TWINFLEX 2000 system is recyclable ground wood or offset. The technology also binds coated two-sided paper, as PURs can adhere the most difficult of coated stocks because of their chemistry and molecular weight.
 
PUR Benefits
 
From PUR's inherent tensile strength, the thin, flexible film gives excellent adhesion. Page pulls and flex are unsurpassed. Even with 180-degree stress on a coated heavy sheet, PUR retains its flexibility and strength. A comparable thin film of EVA would lack the tensile strength to meet minimum customer requirements.
 
The strong, pliable, thin film of PUR achieves excellent layflat with minimal mousetrapping. The reader does not get a book that wants to spring shut.
 
PUR's superior heat/cold resistance allows books to survive temperature extremes as low as -40°F and as high as 200°F.
 
For more productivity and line speed gains, PUR's low application temperature of 250°F generates fewer fumes. Because of this lower application temperature, little or no wrinkling occurs when binding cross grained paper stock. Today's PUR hot melts develop high strength quickly. Tests show bookbinders can trim the paper in 30 seconds.
 
In all, the TWINFLEX 2000 system brings improvements in book quality, integrity and durability for a long life of heavy use. The system could point to a significant change in approaches to bookbinding.
 
 
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