GB1145677A - Heat stabilization of polyamides - Google Patents

Abstract

1,145,677. Polyamide filamentary materials. INVENTA A.G. FœR FORSCHUNG UND PATENTVERWERTUNG, ZœRICH. 14 Sept., 1967 [16 Sept., 1966], No. 41933/67. Heading B5B. [Also in Division C3] In a process for the formation of heatstabilized stretched products of a linear polyamide, a copper compound and an organic nitrogen compound are added to the polyamideforming starting materials, the polyamide is prepared by polymerization and formed into a stretchable product, a solution or dispersion of an alkali metal halide is applied to the product and finally the product is stretched. In a modification, the copper compound and organic nitrogen compound are mixed with polyamide chips, the mixture formed into a stretchable product, a solution or dispersion of an alkali metal halide is applied to the product and finally the product is stretched. The stretchable product may be a filament, monofil or film. Specified organic nitrogen compounds include di - beta - naphthyl - para - phenylenediamine, N - phenyl - beta - naphthylamine, N - acylpara - aminophenol and mercaptobenzimidazole. Suitably, the polyamide is formed into a stretchable product by spinning, and the alkali metal halide is added to the spin finish, to which a light stabilizer or an optical brightener may also be added if desired. Alternatively, the solution or dispersion of alkali metal halide and any other desired additives may be applied consecutively to the stretchable product. Thus the secondary constituents of the stabilizer combination may be applied to the as-spun filaments in aqueous solution or in an organic solvent with a first applicator roll, the spin finish then being applied with the second applicator roll, if desired also with another addition of a stabilizer constituent. In this way, application of the stabilizer constituents in coats is possible and thus stabilizer constituents which are incompatible with the spin finish, but soluble in water or organic solvents, can also be applied. Conversely, the stabilizer constituents can also be applied in only the outer layer of the fibre if the spin finish is applied with the first applicator roll and the stabilizers are applied with the second applicator roll. In this way, the stabilizer develops its action only on the surface of the fibre, where the oxiditative damage primarily occurs, this action being then intensified. Harmful side effects of the stabilizer which may possibly occur due to catalytic chain disintegration are also in this way restricted to the surface of the fibre. In the example, polyamide chips, with cuprous chloride and mercaptobenzimidazole applied thereto in powder form are melted at 270‹ C. and spun into filaments. A spin finish containing potassium iodide is applied by means of applicator roll. The yarn so obtained is stretched to a ratio of 1:3À505.