manufacturing process of cracks and dimensional body mussels)

摘要

1498466 Crack-free injection mouldings BAYER AG 5 May 1975 [11 May 1974] 18666/75 Heading B5A Crack-free precision injection mouldings, particularly for use as high-voltage insulators, are made by injecting a resin comprising a polyester resin and 1 to 30 wt. per cent of shrinkage-reducing thermoplasts at substantially room temperature under pressure into a mould heated to above 70‹ C. and maintaining the pressure until the resin solidifies. Optionally, other additives-e.g., fillers, pigments and reinforcing agents-may be present; and some of the polyester (up to 60 wt. per cent of the total mixture) may be replaced by other known casting resins, e.g. epoxy resins. The mouldings are preferably made by injecting a mixture comprising 24-70 wt. per cent unsaturated polyesters, 20-75 wt. per cent polymerizable monomers and 1-30 wt. per cent thermoplasts.