METHOD AND APPARATUS FOR MANUFACTURING BUILDING, STRUCTURAL, AND PACKAGING MATERIALS, AND ARTICLE MANUFACTURED BY THIS METHOD Russian patent published in 1998 - IPC

FIELD: manufacture of building materials. SUBSTANCE: when manufacturing shaped bodies with reduced density and essentially dense surface, basic mass including natural fibrous or fibers-containing material and binding agent is subjected to high temperature and pressure to produce gel-melt that is further extruded into zone with partially dropped pressure where, in working section of extruder, mixture being processed undergoes partial internal expansion. As binding agent, at least one natural biopolymer is used selected from the group including starch, dextrin, pectin, collagen, protein and casein. Moisture content in initial mixture is set within 6-25 wt % range. Mixture is heated and compressed at temperature above 100 C and pressure from 15 to 600 bar so subjecting the mixture, during gel-melt formation, to action of specific mechanical energy within the range from 0.05 to 0.7 kW h/kg. Degree of expansion in the gel-melt escaping extruder is maintained at the level at least 1.1. Apparatus constructed as worm extruder is provided with facilities for partially dropping pressure and for internally partially expanding mixture being processed in working section of extruder. Article has dense upper surface and main bulk structure containing a large number of small cavities. As biopolymer, at least one starch-type substance is present in quantity 5 to 85% based on weight of initial mixture. EFFECT: enhanced process efficiency. 20 cl, 2 dwg