Moulding phenol-formaldehyde resin article - contg powder and fibre filler in differentially heated mould to produce high density skin

摘要

A moulded article is formed by mixing with a formophenolic resin a filler of mineral powder and mineral, vegetable or synthetic fibres and then adding an acidic or basic catalyst and a low b.pt. foaming agent. This mixt. is fed into a differentially heated mould so that the mixt. foams to produce closed cells decreasing from the heated upper region to the cooler lower region whereby to form a high density skin on the moulded article at the lower region of the mould. The method is used for moulding roofing panels. Roofing panels have a high mechanical resistance, and a resistance to atmospheric pollutants. The panels are completely waterproof and fireproof.