Improvements in and relating to the production of artificial filaments, threads, fibres, bands and the like

In the manufacture of artificial threads and like products by extruding a protein solution into a setting medium and hardening the products, the protein is esterified before or after extrusion and the esterified protein is treated with ammonia to convert at least a part of the esterified carboxyl groups into amide groups; the amidation may be effected before or after extrusion and in one form of the process, esterification is effected before extrusion and amidation after extrusion. Esterification may be effected with methanol in the presence of sulphuric acid or with dimethyl sulphate or ethylene oxide. Amidation may be effected with anhydrous or alcoholic ammonia or with aqueous ammonia solution preferably containing ammonium salts as buffers. When esterification and amidation follow extrusion, the extruded products are preferably first hardened in a formaldehyde-salt bath and may then be esterified as described in Specification 690,492. After amidation the products may be further hardened in a bath containing formaldehyde, sulphuric acid and one or more metal salts; alternatively or in addition, they may be insolubilized by treatment in a cyanate bath, as described in Specification 701,645. Examples are given.