Foam mouldings of locally differentiated density - prepd. by selectively cooling the mould with liquid coolant

摘要

Mfr. of foam mouldings having non-uniform apparent density within the moulding or in zones near their surface, comprises locally cooling the mould at those places where the mouldings are desired to have relatively greater density. This is achieved by adding a locally effective liq. coolant. Used for mfr. of foam mouldings whose mechanical strength is to be increased in selected zones, esp. near the surface of flanges or collars, without the need to use more moulding cpd. than for the other zones. The coolant is pref. liq. air or N2 or some other liq. having a low b.pt. Addn. of the coolant is controlled in such a fashion that the cooling at the interface of mould and foam attains its max. effectiveness at the moment of foam formation.