Henkel projected its position as a world leader in the production of industrial adhesives by showcasing a range of innovative product solutions for textile lamination at the Techtextil trade fair in Frankfurt/Main, Germany, in June.

Hotmelt adhesives are playing an increasingly important role in textile lamination. Compared to traditional methods, hotmelt technology offers numerous process configuration benefits, reduces production cost and makes an active contribution to climate protection.
That is why almost all the renowned manufacturers of adhesive applicators are now offering textile laminating machines suitable for a wide range of coating processes.
Hotmelts are supplied in their solid state and are melted at temperatures between 90°C and 180°C. They are then applied in their liquid form to one of the mating substrates, and the two “partners” are then immediately joined together. The adhesive type required will depend on the application process employed, the material being laminated and the associated duty specifications.
“With its brands Liotex and Pur-Fect, Henkel offers a product portfolio able to cover a wide range of applications, enabling the properties of greatly differing materials to be combined within high-performance textile composites,” Henkel said.  Modern application examples include the coating of carpet backs and foam-textile lamination. Henkel has developed high-performance hotmelt adhesives for such operations, ideally matched to the special requirements of each field of application.

Faith reposed in hotmelt adhesives
“In the production of carpets and textile floor coverings, and also in the manufacture of synthetic turf, latex dispersions have until recently been regarded as state of the art for securing the fibers in the backing or ground fabric. However, when investing in new machinery, carpet manufacturers are putting their faith more and more in hotmelt adhesives,” explains Alejandro Schönhoff, product manager, fiber and fabric at Henkel. And there is a reason for this, namely that hotmelt technology offers a number of advantages over latex coating systems.
Hotmelt adhesives comprise 100 per cent solid material. Unlike with latex dispersion systems, no water is wasted in having to dissolve the adhesive for the process in hand. In the case of latex dispersions, moreover, around half the mass applied evaporates in the subsequent drying process. The use of hotmelt adhesives completely eliminates the need for a drying process, with dramatic savings in energy costs ensuing.
 “In a direct comparison, the reduction is around 70 per cent, even taking into account the energy required to initially melt the hotmelts,” Schönhoff assures. A further plus lies in the short open time available with Liotex adhesives. The applied melt quickly cools so that for example the carpeting product can be further processed without any great loss of time. To improve the appearance of the product, a second backing can – with the hotmelt option – also be laminated inline, ie in one production step, significantly simplifying the manufacturing process. And this too is something that latex dispersion technology cannot offer.

Foam textile laminations
Thanks to their good environmental compatibility, modern hotmelt techniques are also now being used for foam-textile lamination applications. Whether for the manufacture of interior automotive cladding or ladies’ bras, laminating with polyurethane-based reactive hotmelts is becoming firmly established as the preferred technology, taking the place of flame lamination – a process in which the material composite is manufactured by passing the top foam layer through a flame. One of the major benefits of hotmelt adhesives is that, in contrast to flame lamination, the application process does not give rise to any CO2 emissions. “And that is something that also benefits composite manufacturers - because switching to this new technology eliminates the need for additional investment in high-cost safety equipment such as activated carbon filters,” comments Norman Woehlbier, likewise product manager, fiber and fabric.
When one takes into account the loss of material that occurs when flaming the foam, the price range of both technologies is very similar. “Aside from the advantages already mentioned with respect to environmental compatibility, hotmelt adhesives of the Henkel brands Liotex and Pur-Fect offer a markedly higher degree of flexibility in terms of the range of laminating materials that can be used,” Henkel insists.  In the manufacture of high-quality braziers, for example, increasing use is being made of aliphatic Pur foams that do not yellow with time, even when in direct contact with UV light. “However, these foams – like many other materials – are not suitable for flame lamination,” says Woehlbier. “So in any direct comparison, hotmelt technology for textile lamination is also able to bring some pretty persuasive arguments with respect to application versatility.”