Production of fibres

Claim 1

A process for centrifugally spinning formaldehyde fibres from a liquid formaldehyde resin which comprises the steps of feeding the resin and a resin-curing catalyst, which at temperatures above 100° C. will cure and chemically stabilize the resin and render it insoluble in cold water, into a rotating spinning cup, directing downwardly towards the cup a flow of cold, humid air, at least part of which flow enters the cup with the resin/catalyst mixture, the temperature and humidity of the air being such that it inhibits drying and reaction of the resin/catalyst mixture whilst in the cup, the rotation of the cup causing the resin/catalyst mixture to flow as an even film over the inner surface of the cup, in the presence of the cold, humid air, and to be spun centrifugally from the outer wall of the cup, in the form of individual, separate fibres which attenuate until they have achieved the desired diameter, providing from below the cup outwardly-directed currents of hot dry air at a temperature such as to heat the fibres to between 50° C. and 100° C. to dry the attenuated fibres and transport them to a collecting zone, removing the dry fibres from the collecting zone, and curing and chemically stabilizing them by heating at above 100° C. until they are insoluble in cold water.