| 摘要 |
A process for the production of rigid polyurethane foams involves reacting a) organic and/or modified organic polyisocyanates with b) at least one relatively high-molecular-weight compound containing at least two reactive hydrogen atoms, and, if desired, c) low-molecular-weight chain extenders and/or cross-linking agents, in the presence of d) blowing agents, e) catalysts and, if desired, f) assistants and/or additives, where the relatively high-molecular-weight compounds (b) containing at least two reactive hydrogen atoms are polyoxypropylene-polyols and/or polyoxyethylene-polyoxy-propylene-polyols containing up to 20% by weight, based on the weight of the alkylene oxide units, of pendant oxyethylene units containing secondary hydroxyl groups and having a functionality of from 3.8 to 4.1, a hydroxyl number of from 385 to 410 mg of KOH/g and a viscosity of from 1700 to 2400 mPaxs at 25 DEG C., and which can be prepared by anionic polymerization of 1,2-propylene oxide and, if desired, ethylene oxide on an initiator molecule mixture comprising sucrose, pentaerythritol and diethylene glycol.
|
