Consolidation of nonwoven inorganic fibrous insulation - by heat shrunk fibres to avoid extraneous solvents or prolonged hot curing

摘要

Fibrous insulation material comprises compacted layers of inorganic fibres into which are entangled fibres of organic material which will contract and/or fuse when heated. The mixt. of fibres is rolled, carded and needled, and then heated to contract the organic fibres and obtain a coherent, non-woven structure of controlled density. Pref. the organic fibres are made from flame retardant grades of polyvinylidene chloride, polyethylene, polyacrylonitrile, polyamide, polyacetate, PVC or polymers or copolymers of styrene, and chopped to lengths of 3.18-38.1mm. The blend should contain 2-10, pref. 3-5% wt. of the organic fibres and be heated at 100-150 degrees C for 1-3 mins. by electrical or steam heating to cause 40-90% longitudinal contraction of the organic fibres. Used for mfr. of fibrous sheet for thermal and acoustic insulation, based primarily on non-flammable fibres of glass, mineral wool and/or asbestos, to controlled densities and with good resistance to delamination. Blending with organic resin as prefabricated filaments avoids resin losses and aq. or solvent handling and recovery problems associated with application of coating resins from soln. or suspension to bind the inorganic fibres together or the prolonged heating at e.g. 200-260 degrees C required to cure conventional thermosetting binder resins.