Heating thermosetting materials using live steam in the mould cavity - to reduce heat transfer cycles and eliminate mould tool cooling

Abstract

Abstract Cycles for moulding particles of thermosetting materials, esp. polystyrene are reduced by vacuum charging to feed particles into a mould cavity in a tool having passages and filters for circulating live steam through the material in the cavity to provide the heat for curing. At least the major part of the heat transfer required by the material is provided by the steam, allowing the mould tools to be operated at relatively low temps., obviating mould cooling between cycles. Mould residence times may be reduced by 70-90% compared with processes involving heat transfer by conduction from the cavity surfaces. The tool is also subjected to less thermal stress.

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