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What makes a well-performing low-application-temperature spine adhesive?

Posted 04/20/2021 by Mark Cunningham, Application Specialist

When working with difficult papers, slow-to-medium setting adhesives deliver better adhesive penetration between pages and onto the cover. Fast-setting products typically are used for high-speed magazine lines when the paper quality is easier to adhere to. The viscosity of the adhesive you choose also is relevant. Higher-viscosity products exhibit improved strength and heat resistance, whereas lower viscosity products can improve pot stability and machining characteristics. 

Low-application-temperature (LAT) hot melts, typically applied at 250-275°F, have gained popularity for paperback, magazine, catalog, and other perfect-binding applications. This unique type of adhesive offers advantages over conventional (350°F) application products, including:

  • Improved thermal stability in both the premelter and applicator pot, which can minimize adhesive degradation and char buildup and reduce downtime, equipment maintenance, and product defects.
  • Shorter post-application cooling times, which reduces the wait time to trim. Shorter wait times improve line speeds and productivity while also reducing smearing and wrinkling issues.
  • Less water vapor pulled into the adhesive from the cover stock, which can minimize voids in the adhesive film and improve the strength of the finished product.
  • A safer work environment around the applicator pot.

LAT hot melts do not compromise strength and flexibility. Both page-pull and page-flex values rival those of their 350°F counterparts. LATs also can deliver significant cost savings through lower energy consumption. H.B. Fuller has a complete line of LAT hot melts to satisfy one-shot, perfect-binding applications. These hot melts are versatile and bond to many substrates, including papers with a high percentage of recycled content or modified with additional fillers and sizing agents. 

Critical success factors when applying LAT spine glues

  • Application amount 20-25 mils is an optimal amount for typical publications.
  • Application temperature For best results, check that the adhesive falls within the specified viscosity range (4,000 to 8,000 cps is optimal) at the application temperature.
  • Surface preparation Prepare the spine adequately for the paper type and adhesive you are using.
  • Placement of the adhesive Incorrect application of the adhesive can compromise performance and aesthetics.
  • Adequate compression Ensure the gap settings in the wheel pot and the cover station are set appropriately for optimal penetration.
  • Condition of the dispensing/ application equipment An adequate preventative maintenance schedule alleviates many pain points with equipment and prolongs its life cycle.

To learn more about H.B. Fuller LAT spine adhesives, contact your local sales representation or contact us online.

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