Orientierte Schichtstrukturen

摘要

A sandwich composite comprises (A) a core of an oriented polystyrene foam having closed cells and an elongation of less than 50%, and (B) thermoplastic skins (heat formable at 50 degrees-230 degrees C) which attached using melt adhesives such as ethylene/vinyl acetate copolymers. The polymers for foam and skins have tensile moduli which are higher than 10,550 kg/cm2. The composite is flexible. The skins have an elongation which is higher than t/R where t is the skin thickness and r is the bending radius. In particular the elongation is more than 5%. The composites ahve good dimensional stability and are water-impermeable and grease-resistant. Deformation temperatures are 80 degrees-100 degrees C. Thermoforming is easy and uses are for packaging food and cosmetics. Boxes with sub-compartments or pouring lips are possible. Specially the skin is of biaxially oriented polyvinyl chloride and contains up to 25% by weight of a pigment such as TiO2. The skin/core adhesion is at least 98.4 g/cm.