Improvements in or relating to the manufacture of polymeric materials

A process for the manufacture of cellular materials by interacting polyesters and organic polyisocyanates is characterised in that the polyisocyanate used is a polyisocyanate composition comprising more than 50% by weight of diphenylmethane diisocyanate and at least 5% by weight of polyisocyanate containing more than two isocyanate groups, sufficient of said diisocyanate and polyisocyanate being present as carbamyl chloride derivatives to provide an ionisable chlorine content of 0,01% to 3,0%, preferably 0,1% to 1,0% by weight of the polyisocyanate composition. The polyisocyanate containing more than two isocyanate groups can be (1) added directly to the diphenylmethane diisocyanate, e.g. as benzene, toluene, diphenylmethane, diphenyl or diphenyl ether triisocyanates; (2) formed by interaction of some of the diphenylmethane diisocyanate with a polyhydric alcohol; (3) formed by partial polymerisation of the diphenylmethane diisocyanate to form isocyanurate derivatives; (4) present as the result of the manufacture of the diphenylmethane diisocyanate from a crude diaminodiphenylmethane containing triamines and other polyamines. The carbomyl chloride derivatives comprise di- and polyisocyanate compounds in which some or all the isocyanate groups have been converted to N-substituted carbamyl chloride groups, for example by direct addition of hydrogen chloride. In a typical example (1) a mixture is prepared of a polyester (from pentacrythritol, butylene glycol, adipic acid and phthalic anhydride), and alkylphenolethylene oxide condensate and water. To produce a foam there is then added a diphenylmethane diisocyanate composition. This is obtained by phosgenation and heating of an aniline-formaldehyde condensation product and contains about 30% of derivatives of triamines and also isocyanurate polymers and has an ionisable chlorine content of 0,5%.ALSO:A polysocyanate composition for use in the preparation of cellular polyurethanes comprises more than 50% by weight of diphenylmethane diisocyanate and at least 5% by weight of polyisocyanate containing more than two isocyanate groups, sufficient of said diisocyanate and polyisocyanate being present as carbamyl chloride derivatives to provide an ionisable chlorine content of 0,01% to 3% of the polyisocyanate composition. The polyisocyanate containing more than two isocyanate groups can be (1) added directly; (2) formed by interaction of some of the diphenylmethane diisocyanate with a polyhydric alcohol, e.g. with tri