Dreischichtplatte

摘要

A sandwich construction sheet of unlimited length consists of a core and two skins; the core is made up of thermoplastic polymers which are incompatible with each other in which small non-thermoplastic particles are distributed fairly uniformly; the two skins are high modulus material. Pref. thermoplastics for the core are polyethylene, polystyrene, polypropylene and PVC, at least two of these being present; pref. non-thermoplastic particles are paper, sawdust or similar, expanded mica or aluminium foil; pref. skin materials are laminates, aluminium or steel, wood or FRP. The three layers are pref. bonded together with urea type resin, or adhesive film of mixed ethylene polymer. Flame retardants can be incorporated. The laminar prods. can use thermosetting scrap. They are quite rigid in thickness of 1.5-10mm. Their water absorption is less than 1%, they can be surface-coated, embossed or printed. The figure shows the cross-section of the construction, with the outer skins (1) and the thermoplastic particles (4,5) in the core mix. The core also contains the non-thermoplastic particles (6); they can amount to e.g. 40 wt.% aluminium foil to make a sound-absorbing prod. ADVANTAGE - The prods. utilise the types of thermoplastic scrap arising in domestic waste materials.