Washable thermoplastic elastomer foam and articles incorporating same

Abstract

A thermoplastic elastomer (TPE) foam having a soft open-cell inner layer and a washable closed-cell outer layer which surrounds and substantially seals the inner layer, and which may be used alone or in combination with other components to produce useful articles. The TPE foam includes a base resin which is a styrenic block copolymer, and a foaming agent. A process of forming and molding the TPE foam includes using a shutoff nozzle to prevent the foaming agent from activating before reaching the mold cavity, using an oversized gate to minimize shear heat, and using oversized vents. An earplug may be constructed by molding the TPE foam over a core or body formed from a material which is denser than the TPE foam. A first earplug design may employ a constrained layer damping effect, while a second earplug design may employ an adjustable sound attenuation effect.