PRE-INSULATED PIPES AND PROCESS FOR THEIR PRODUCTION

摘要

Pre-insulated pipe comprising an inner pipe surrounded by a casing with arranged thereinbetween a single one-piece layer of insulation material comprising a polyisocyanurate-modified polyurethane foam. These pre-insulate d pipes can be produced in a continuous process, wherein a foaming mixture comprising (a) a suitable polyol component, (b) a suitable polyisocyanate component in such amount that the isocyanate index is at least 150, (c) at least one polyisocyanurate catalyst and optionally one or more polyurethane catalysts, and (d) suitable ancillary chemicals, is continuously brought int o contact with the outer surface of an inner pipe and is allowed to expand int o a polyisocyanurate-modified polyurethane foam, after which a casing is appli ed around this a polyisocyanurate-modified polyurethane foam.