GB900942A - Improvements in or relating to methods of and means for foaming thermoplastic synthetic materials - Google Patents

Abstract

900,942. Chambers for heating thermoplastic particles. MATZLER, W., [trading as MEDULTRA W. MATZLER]. Aug. 26, 1958, No. 27295/58. Class 64 (2). In a container 1, superheated steam or hot air passes, e.g. from nozzles 6 (selected for greater flow nearer the bottom) in hollow, stirring arms 3 or from perforations in a double wall, into a mass 12 of polystyrene particles containing expanding agents, so that each particle expands to a cellular condition ready for use in moulding. The container is charged initially with particles already expanded so that fresh, unexpanded particles fed in from a hopper 7 and spread by a distributer 13 are heated gradually at first. The apparatus is for batch or continuous operation. When the level of the particles reaches an element 11, an outlet 8 is opened until it is closed by the action of an element 10 when the level falls. The heights of the elements 10, 11 are adjustable to control the density of the product but partiallyfoamed material may also be taken off from upper outlets 14. Members 15 on the container wall increase the turbulence. The container may be tilted and the hot fluid supplied from the underneath of the container wall or the container may be pivotable to the horizontal position so that the movement of the particles can be varied. The heating fluid may be introduced separately from the stirrer, through fixed pipes and it may be introduced through perforations in a double-walled portion of the container 1. The stirrer may be stationary and the container rotated. In the event of power failure, the particles are automatically cooled by the introduction of air or by dousing with water and a wetting agent to prevent them fusing together.