BOOK SPINE GLUING WITH PUR ADHESIVE

Although the first PUR application in bookbinding industry was in1989, development of improvement in properties of

that type of adhesives and the necessity to satisfy bookbinding market have made the last years that PUR adhesive becomes the expected substitute of traditional hot-melts. Many reasons can sustained this fact and probably the most important of which are its superior adhesion and the ability of a PUR-bound book to lie flat when open.

The changes in paper weight, coating and inks used in today’s printing applications require higher features for the latest PUR adhesives. The newer PUR products grab and hold heavily coated papers together tenaciously. Page pulls are quite better with PUR than with traditional adhesives and PUR glues remain virtually unaffected by ink migration.

Books bound by PUR will not fail at extreme temperatures –even over 200°F or under -40°F–,

PUR’s lower operating temperature avoids wrinkling in the book and is also somewhat malleable as it cures, allowing the paper fibers to return to their original orientation.

With applied thickness of 0.3-0.4 mm, half the standard thickness of hotmelt, there is much less chance for the material to build up on trimmer knives. PUR is the only binding material that is totally resistant to solvents and oils.

PUR application can be done with open pot (roller) or adjustable width coating gun. Open pot needs a frequently maintenance and cleaning. Coating gun systems are quite better to clean and maintain and allow –with an air-dryer system or nitrogen– keep the adhesive at an innert atmosphere, without moisture, to prevent premature curing of the PUR.

PUR gluing on milling books instead of sewing them has also a cost saving because it is more labor-intensive and requires a greater capital investment, although its finishing quality, specially in hardcover books with a great added value.

MELER GROUPCorporate HeadquartersE-mail: info@meler.es

w w w . m e l e r . e uP.I. Los Agustinos, Calle-G, Nave-D-43E-31160 ORCOYEN. Navarra (Spain)Tel.: +34 948 351 110 - Fax.: +34 948 351 130C

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• Melting unit based on non-stop drum unloader for 20L PUR blocks- ‘melt on demand’ characteristic- air-dryer system to prevent premature adhesive curing- pneumatic adjustment of pressure relief valve (by pass)- touch screen for setting and controlling parameters- four colors warning beacon

• Heating hose with the right length according to installation (typ. 2,4 m)

Complete ‘meler’ system for book spine gluing with PUR adhesive includes the following elements:

• Adjustable width coating gun (0-60 mm or 0-100 mm) with fast cut-off injector- pneumatic control solenoid valve- anti-drop tray

• Pattern control to run the application according to the book length- book detection photocell to start cycle- encoder for programming the length in mm

• Holding and adjusting support to set the gun in position (*)• Trolley system for gun-support assembly (*)

(*) This elements must be designed according to the machine characteristics (brand and model) where the system will be installed.