Kundenmagazin 2016-05 EN

For superior edges: PUR hot melt adhesives The introduction of reactive adhesives based on polyurethane (PUR) repre- sented a great leap forward in the de- velopment of hot melts. These PUR adhesives are becoming more and more established for applications with highest demands, especially regarding the visual appearance. The completely moisture-cured hot melts provide addi- tional technical benefits compared to PO adhesives, e.g. high resistance to water, vapour and chemicals, as well as to temperatures well above 120 °C. The reduced application amount facili- tates almost invisible bondlines, making PUR adhesives the top choice among hot melts when it comes to edge- banding of premium furniture parts. Because PUR adhesives react with water molecules, they are supplied in moisture-proof packaging units and are processed in special melting units to avoid contact with humidity. Numerous processors of Jowat products from the furniture industry already carried out a direct transition from EVA to PUR hot melt adhesives and installed PUR ap- 10 How is PUR-granulate made? Underwater granulation The granulation method patented by Jowat is not only innovative – due to the mois- ture-curing character of the adhesive, it also seems unbelievable. The hot melt granules are formed underwater. During the manufacturing process, the molten material is extrud- ed through the holes of a die plate into cold water. The extruded threads of the molten material are cut off by a fast rotating knife into short pieces. The high temperature difference between the molten material and the cold water, and certain physical laws cause the small cutoffs of molten material to contract, thus forming the typical spherical pellets – granules.

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