Imperial Chemical Industries Limited

Robert S Hampson

James P Brown

Graham Gibbins

George W Ball

Frederick T Kelly

An organic polyisocyanate composition contains from 99 to 60 parts by weight of a liquid organic polyisocyanate and from 1 to 40 parts of a 90:10 to 10:90 mixture of a wax and a liquid ester having a molecular weight of at least 250, for example an alkyl ester of an aliphatic carboxylic acid derived from an alkyl alcohol containing from 3 to 30 carbon atoms and a saturated or unsaturated fatty acid containing from 10 to 25 carbon atoms. The composition is useful for the manufacture of sheets or moulded bodies by the hot-pressing of a lignocellulosic material and promotes release of the material from the press. The composition is preferably applied in the form of an aqueous emulsion.

Wax dispersions and their use in the manufacture of sheets or moulded

Sheets or moulded bodies, for example particle board, are manufactured by hot pressing a lignocellulosic material in contact with an organic polyisocyanate and a wax release agent which is a vegetable wax, a modified vegetable oil, a microcrystalline wax or a mineral wax, said wax release agent having a melting point of at least 70.degree. C. Preferably the wax release agent is applied to the lignocellulosic material in the form of a dispersion in an aqueous emulsion of the polyisocyanate. The process facilitates the release of the sheets or moulded bodies from the caul plates or platens of the press.

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Oldham, United Kingdom

Robert S Hampson