| abstract |
Prodn. of urethane foams by the one-shot process is carried out with polyester-polyol (I) and an excess of polyether-polyol (II) over (I), together with polyisocyanate, blown agent, stabiliser, catalyst, opt. emulsifier, dyes and filler and other conventional additives, e.g. antioxidant and flame retardant. (I) and (II) are supplied to the mixing head in separate streams and a mixt. of polymethylsiloxane/polyether copolymer (III) and an excess of fatty aid sulphonate (IV) and opt. fatty acid sulphate (V) is used as foam stabiliser. The properties of the foam are similar to those of a pure polyester foam, e.g. w.r.t. compression hardness, but the air permeability is much better. The resistance to hydrolysis is improved by the use of (II). The stamping property is also excellent, allowing satisfactory stamping even of relatively great thickness and critical contours. Densities of 15-50 kg/m3 can be obtd. The addn. of (II) also reduces the cost. |