Moulding closed cell phenolic resin foams for insulated roofing - using fillers and mould temp differentials to modify the foam

摘要

Mouldings made of phenol-formaldehyde resin by blending successively with the resin powdered and fibrous fillers, acidic or basic catalysts and a low boiling pt. blowing agent, then injecting the mixt into a mould having temp. gradients between different regions of the cavity. The different temps. result in different degrees of cell expansion and hence different densities within the moulding. Specif. the upper part of the mould is relatively hot. The moulding is formed with a strong skin and closed cell foam core which is less dense in its higher parts (as moulded). Esp. for mfr. of insulating roofing materials, with the foam being developed in a mould lined with e.g. cement or stone tiles which become integrally anchored to the moulding surface. Produces lightweight panels of inflammable insulating materials. The presence of fillers reduces the brittleness of the foamed resin.