GB1042228A - Continuous production of polyamide articles - Google Patents

Abstract

Filaments, films and ribbons of high M.W. linear polyamide are produced from either (a) a C6- 12 o -aminoaliphatic carboxylic acid, (b) a polymethylene diammonium salt of a C8- 24 aliphatic a ,o -dicarboxylic acid or (c) an aromatic diammonium dicarboxylate salt or aminocarboxylic acid as defined below, by (I) pumping the monomer in aqueous solution along a tube which has an internal diameter not exceeding 4.5 cm. and is heated to the polymerization temperature, the pressure being at least 14 atmospheres at the entry of the tube decreasing as a continuous monotoxic single-valued function of the distance along the tube to atmospheric or below at the exit but at any point permitting evolution of steam so that at least 90% of the total theoretical water of condensation is removed, (II) collecting the polyamide so formed in a heated reservoir and (III) withdrawing the collected material and melt spinning it characterized in that the rate of introduction of monomer into the tube is varied so that the polyamide level in the reservoir remains constant the rate being reduced from M + a to M - a by reducing the rate of introduction of solution by a factor (M + b)/(M + a) and reducing the solution concentration by a factor (M + b)/(M - a) and conversely increasing the rate of introduction of monomer by increasing the rate of introduction of solution by a factor (M + a)/(M + b) and increasing its concentration by a factor (M - a)/(M + b), M being the mean polyamide output required in mass per unit time and a and b being fractions of M, a between 0 and 1/5 M and b between 0 and 1/2 a. The aromatic diammonium dicarboxylate salt may be derived from a diamine of formula NH2-X-NH2 and a dicarboxylic acid of formula HOCO-Y-COOH wherein X represents a chain of p-methylene groups containing, not joined directly to nitrogen; 1-, m- or p-phenylene links and Y is a chain of r-methylene groups containing sm- or p-phenylene groups, q and s being 0-2 at least one not being 0, p being at least 2 but at least 6 if q is 0, r being at least 4 if s is 0, p+r being at least 6. The aromatic amino-carboxylic acid may be of formula NH2-Z-COOH wherein Z represents a chain of t-methylene groups and, not joined directly to nitrogen, um- or p-phenylene links, u being 1 or 2 and t at least 3. X, Y or Z may carry alkyl substituents and contain -O-links providing the groups: -O-O-, -O-CH2-N- and -O-CH2-CH2-CO-are absent. Monomers specified include hexamethylene diammonium adipate. Monofunctional acids and amines, e.g. acetic acid, and free diacids or diamines, e.g. hexamethylene diamine may be prosent in the reaction mixture. Other additives may be dyes, pigments, e.g. TiO2, dyestuff precursors, heat and light stabilizers, plasticizers, delustrants, other polyamides and other resins. The process may be carried out so that the rate of introduction of water into the polymerization tube is constant.