GB1420838A - Fibres and their production - Google Patents

Abstract

1420838 Urea-formaldehyde filaments TEIJIN Ltd 22 May 1973 24475/73 Heading B5B [Also in Division C3] A fibre comprises a thermosetting or thermoset resin consisting of the reaction product of (A) urea, (B) a monomer other than urea which can form a methylol group by the addition reaction with formaldehyde, and (C) formaldehyde, the molar ratio of C to A and B being more than 1À5 : 1 and the molar ratio of A to A and B being 0À5 : 1 to 1 : 1. A process for preparing a fibre comprises (1) reacting in an aqueous medium A and C and optionally B in the above molar ratios; (2) adding a curing agent to the resulting aqueous solution of the water-soluble condensate obtained; and (3) dryspinning the resultant solution by extruding it from a spinneret into a heated gaseous atmosphere, e.g. air or an inert gas, at a temperature of at least 100‹ C. Suitable monomers (B) are melamine, a phenol, thiourea and an amine, e.g. aniline, hexamethylenediamine and metaphenyienediamine. The curing agent may be an ammonium salt of an organic or inorganic acid or zinc chloride. The aqueous solution may be concentrated prior to the addition of the curing agent to such an extent that the viscosity thereof becomes at least 100 poises at 20‹ C. upon addition of the curing agent. The dry spun filaments may be heat-treated for at least 1 minute at 80-230‹ C. In the examples fibres are formed by heating an aqueous solution of formaldehyde and urea alone and together with any one of phenol, thiourea or melamine under essentially neutral conditions in the presence of aqueous NH 3 . The resulting solution is concentrated, aqueous NH 4 Cl then added and the solution is then dry spun. In a further example the aqueous solution which is dry spun comprises a mixture of a urea-formaldehyde condensate, a urea - thiourea - formaldehyde condensate and NH 4 Cl. The dry spun filaments are heat treated.