EVA-coated thermoplastic sheet for thermo-formed container closures - for simplicity of sealing together incompatible components

摘要

Composite sheet for mating sealed closures for plastics containers comprises a layer of sheet material (I) which can be thermoformed and is coated on one face with layer of ethylene-vinyl acetate (EVA). The composite sheet is thermoformed to a suitable shape, fitted to the container, and bonded to its rim by heating to 150-200 degrees C to fuse the EVA. Pref. the sheet is made by co-extrusion of the two layers. More reliable than mechanical closures: simpler than using melt adhesives applied when the lid is to be fitted to the container; suitable for joining lids and bodies made of fusibly incompatible thermoplastics; quicker than ultrasonic welding.