The development of processes and products that save energy and resources not only makes an important contribution to environmental protection but also benefits industrial users. By using sustainable product solutions, they can improve their competitiveness. With adhesives and systems for the woodworking and furniture industry, Henkel demonstrates how this can be done. Under the DORUS and PURmelt brands, the company is now presenting an extensive portfolio of optimally integrated products, processes and services whose use ensures lasting benefits to both the user and the environment. The latest example is the development of the innovative hotmelt called DORUS Hot Sealing.

New laminating process for the furniture industry
Until now, urea and PVAc glues have been mainly used to lamination furniture surfaces with finishing films. In cooperation with the HOMAG Group and Nordson Corporation, Henkel has developed a new process called reacTec lamination ? a process that is notable for its outstanding surface quality and high environmental compatibility. By developing its innovative DORUS Hot Sealing hotmelt, Henkel has laid the foundations for the successful realization of this advanced process technology.

DORUS Hot Sealing, an innovative hotmelt adhesive
So far, hotmelts have only been partially suitable for the lamination of furniture surfaces. With their limited film hardness and low temperature stability, they compare unfavorably with processes like urea resin gluing. To overcome these shortcomings, a new generation of hotmelts had to be developed. The outcome is the DORUS Hot Sealing hotmelt that meets all the requirements in terms of temperature stability and surface hardness.

Choice of two glue coating processes
A major challenge in implementing the new machine technology was the new adhesive’s very short open time. The new adhesive system can be applied to the finish foil by two different methods.

• In the single-stage inline process, the finish foil is coated directly with the adhesive during the lamination process. The finish foil is then guided over a heated roller in order to raise the adhesive to the temperature required for bonding it to the carrier panel. Depending on the wrap angle and size of the oil-heated rollers, it is possible to achieve significantly higher feed rates than with UF glues or dispersions.
• In the two-stage process, on the other hand, the back side of the finish foil is first pre-coated with the adhesive in a stationary unit outside the laminating line. The adhesive is then thermally reactivated in a second step during lamination upon contact with the heated laminating roller.

Which of the two options the customer chooses depends on the specific application. Key factors here are parameters such as the number of items to be produced, the width of the carrier material and its availability.

reacTec lamination scores in direct comparisons
Compared to the three familiar bonding processes with urea, PVAC and EVA hotmelts, the new reacTec laminating process has considerable advantages. These include the cost of investment, shop floor footprint, the possibility of laminating flat surfaces and edges, production reliability and the emission-free production of bondlines. On top of this, unlike waterbased UF and dispersion adhesives, no moisture is introduced during application. This eliminates the risk of wood-based materials swelling and markedly improves surface quality. In addition, the drying step conventionally required can be omitted, and greater heat resistance and a harder surface are achieved than with EVA-based hotmelts.

Henkel AG & Co. KGaA