| 摘要 |
<p>Polyol combination comprising (a) 60 to 95 parts by weight of a polyol component having an average nominal functionality of at least 2.1, an average aromaticity in the range of from 5 to 35 wt.% and an average hydroxyl value in the range of from 200 to 700 mg KOH/g; and (b) 5 to 40 parts by weight up to a total of 100 parts by weight of at least one polyethylene glycol having a molecular weight in the range of from 200 to 1000. The polyol component (a) may consist of a blend of at least two polyols, suitably an aromatic polyol and an aliphatic polyol. The polyol combination is suitably used in a formulation which additionally comprises one or more fire retardants other than dimethyl methyl phosphonate, one or more blowing agents, at least one catalyst and usual auxiliaries. Fire-retardant rigid polyurethane foams can be prepared by reacting the polyol combination with a polyisocyanate component in the presence of at least a catalyst, a foam stabilising agent and a blowing agent.</p> |
