Henkel Purmelt 3300 series

PrintWeek India launched a special publication The 1000 in the month of January 2012. This special publication has special features which include gold and silver foiling and special binding.

For the first time, PrintWeek India used PUR binding technique for its special publication. This was Purmelt QR 3317 BR adhesive. The Purmelt 3300 series of adhesive has two products launched in India. They are QR 3315 T and QR 3317 BR.

P Sajith, marketing director at Welbound Worldwide, the manufacturer of the post-press equipment for book printing industry, says: “One of the key issues challenging the book printing industry in India is the necessity to thread-sew book blocks before cover pasting. At the moment, thread sewing is the only bottle-neck in book binding. We have realised that PUR hotmelt is the only solution for such jobs.”

This new generation of PUR adhesives is distinguished particularly by its tremendous adhesion to a multitude of different paper types and various other materials.

Sandeep Pai, SBU manager- graphic arts at Henkel India, says: “With a coat thickness of only 0.3 to 0.6 mm, they differ noticeably from conventional adhesive systems. Depending on air humidity and paper moisture, about 30% of the ultimate bond strength can be achieved after about six hours, depending on the grade of PUR. Final curing takes a maximum of about 24 hours. After reaction, the Purmelt film displays high flexibility and bond strength at both high and low temperatures. Brochures and  books bound with Purmelt show no loss of quality at temperatures of up to 120°C and remain elastic rather than becoming brittle even down to temperatures as low as minus 40°C.”

Pai adds: “The adhesive is still roundable for a definable period after perfect binding/gluing off with Purmelt. Even after final curing, the book spine permanently retains the desired rounded shape because of Purmelt’s physical properties. After final curing, Purmelt is absolutely immune to the migration of mineral oils from the printing inks. This yields considerable benefits in the converting of papers printed in the sheetfed offset process. The recycling process also benefits from the extreme hardness of Purmelt, as it can be filtered with ease during paper recovery. Entrainment in the paper is excluded, thus eliminating the risk of stickies.”

As of now there are ten print firms who have adopted PUR technology in India and the number of users is increasing.

This include installations at Watchtower, Repro India, Lovely Offset, Printwell, Sanat Printers, HT Burda, Thomson Press, Avantika Printers, Pragati Offset, Replika Press and Sahaya Print Services.

Purmelt has already made in-roads into the hard cover sector as well.

Hardcover books
What would human knowledge be without books? Unchronicled, it would be quickly forgotten. Books can transcend the passage of time, even century after century; when it comes to long-term value and sturdiness, they are vastly superior to all modern information media.

Book binding quality depends in no small measure on the right adhesive. Whether for producing book cases, spine gluing, backlining or casing-in: Purmelt range of hotmelts is comprehensive and crafted to perfection, with special products for all types of applications.

Pai says: “Bindings done with Purmelt can take the heat above 80 °C as well as be left out in the cold below minus-20 °C. So the joy of reading is sure to last for years. In a practical test, Purmelt-bound literature withstands more than three times as much pull forces than bindings made with conventional hotmelts.”

Pai adds: “Purmelt out-performs dispersion adhesives at length, too; and also wins hands down in terms of film elongation and yield strength. For even the toughest tasks, for example, when it comes to coated stock with full-surface printing or cross grain binding, Purmelt adhesives constitute a real alternative to conventional edition binding with thread stitching.

With use of Purmelt, high speeds, coupled with substantial reductions in application quantity is already a reality.”

Polyurethane hotmelts
The product Purmelt is a reactive polyurethane hotmelt. As a result of its prepolymers, it is moisture curing.

Pai says: “The outstanding adhesion to the page edges guarantees extremely high binding strength. In the curing process there is a reaction of the polyurethane hotmelt with moisture from the air and paper.”

Cutomer speaks
New Delhi-based book printer Replika Press has adopted PUR technology for its book printing in the binding division. Replika Press cited the need to move away from thread sewing as the primary reason behind opting for PUR.

Bhuvnesh Seth of Replika Press, says: “Soon all softcover books at Replika will be threadless and will have PUR binding technology. Henkel’s Purmelt adhesive are proven for its strength and would enable the binding of even thick books at high speed.”

Replika now has a solution for every book that can be printed on paper with capability to produce runs from 500 to 5,00,000 and deliver soft-case and hard-case with perfect or PUR bound with added application of special finishes, UV varnish, die-punching, foil stamping and blocking.

Hyderabad-based Pragati Offset has opted for PUR (polyurethene reactive) over standard hot melt adhesives for binding hard and soft cover books.

P Narendra of Pragati Offset says: “Integrating a PUR system on an existing machine has its own challenges. What has helped us, is our experience on spine preparation and gluing that are critical to perfect binding.

Superior adhesion over standard hotmelt and layflat capabilities were important reasons for us to opt for PUR. Other benefits of Purmelt include resistance to extreme temperatures, adhering to coated papers, shear strength, less wrinkle on backbone, solvent resistance to name a few.”

There are challenging applications for this type of adhesive. Whatever the challenges of perfect binding, gluing off thread-stitched or thread-sealed books– Purmelt meets almost all the requirements and ensures optimum results in terms of bond strength and flexibility.

SPECIFICATIONS

• Viscosity (Brookefield, @130 °C.)  2000–4500 Cps
• Density   1.1 g/cc
• Softening Point  60 °C
• Solid Content  100%
• Contact  Sandeep Pai, Henkel India
                  +91 22 39296726, +91 9324201229
                   sandeep.pai@in.henkel.com
                   www.henkel.com

THE ALTERNATIVES

• Dura Pur
  Dura Pur hot melt adhesives combine the speed of hot melts with the strength of structural thermosetting adhesives. They have superior initial handling strength and are VOC solvent free. These adhesives are cured by a reaction with water. In most cases, sufficient moisture already exists in the air or in the materials being bonded but some environments require the addition of moisture through humidification systems to aid curing.
  Contact  Dural
                  + 514 636 6230
                  durapro@dural.ca
                  www.dural.ca
• H B Fuller Lunatack HL3356
  Lunatack HL 3356 is a high adhesion on difficult covers. It has ideal thermal stability. It is suitable for disc and wheel application at all speeds and has long open time for production flexibility.
  Contact  H B Fuller Europe
                  +41 44 315 7700
                   www.hbfuller.com