Process for the preparation of closed-cell urethane-, urea- and isocyanurate groups containing rigid foams and their use

摘要

Essentially closed-cell rigid foams containing urethane, urea, biuret and isocyanurate groups are prepared by reacting a) organic polyisocyanates with b) mixtures of b1) polyesters containing at least two hydroxyl groups and having an OH number of greater than 150 and/or polyethers containing at least two hydroxyl groups and having an OH number of greater than 200, and b2) ethylene oxide-containing polyethers containing at least two hydroxyl groups and having an OH number of less than 100, in the presence of c) isocyanate trimerisation catalysts as catalysts, and d) water as blowing agent, and optionally e) chain extenders and/or crosslinking agents and f) assistants and/or additives, at a characteristic number of greater than 110.