TPU and PP joined via plasma, and nothing more

At next month’s Fakuma exhibition in southern Germany, plasma treatment system supplier Plasmatreat plans to mold a two-component part of polypropylene (PP) and thermoplastic urethane (TPU), with the materials joined using only a plasma treatment applied inline, with no need for adhesive, welding or other mechanical means.

Molded during the show will be the small tubes one can use to blow a balloon; a TPU membrane lets air pass into the balloon but not escape. Typically these parts—the tube and the membrane—are molded separately and then welded, glued, or otherwise brought together. Instead, Plasmatreat will demonstrate the molding of both parts, followed by local plasma treatment in ambient conditions (its Openair process) of the PP tube by a Plasmatreat system mounted on the injection molding machine. This treatment is swift enough so that the TPU can then be overmolded onto the PP.

According to Plasmatreat, its system raises the surface tension of PP above 72 mJ/m², making the adhesion possible. In a secondary step designed to demonstrate how the plasma treatment improves the printability of the PP, a tampon printing machine will decorate the tubes. Both treatments are robot-controlled. —[email protected]