Patent GB-582520-A (GB)
Title: Modification of the properties of filaments, films and other shaped articles derived from nylon
Filed: 1944-08-15
Abstract: Undrawn filaments, bristles, yarns, fabrics, films and like articles derived from a nylon are given an improved reversible extension by heating in the presence of an alcohol, formaldehyde in the vapour form, and an acidic catalyst.  The alcohol also may be used in the form of a vapour, and conveniently the nylon articles are first impregnated with the acidic catalyst and then heated to 80-150 DEG C. whilst exposed to formaldehyde and a volatile monohydric alcohol both in the form of vapour.  Suitable alcohols for the process are methyl, ethyl, propyl, iso-propyl, n-propyl, iso-butyl, n-butyl, octyl, dodecyl, and methallyl alcohols, castor oil fatty acids, cyclo-hexanol, ethylene glycol, diethylene glycol, b b 1-dihydroxyethyl sulphide, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and benzyl alcohol.  Mixtures of alcohols may also be used.  Catalysts specified are phosphoric acid, ammonium dihydrogen phosphate, oxalic acid, maleic acid, glycollic acid, lactic acid and citric acid.  Additional ingredients may be added such as wetting, dispersing or swelling agents, e.g. cetyl pyridinium bromide and sodium cetyl sulphate.  The products of the invention may be finished or treated in any way, for example, they may be cold drawn.  The following examples are given.  (1) Polyhexamethylene adipamide yarn is steeped in an aqueous solution of an acidic catalyst at 50 DEG  C., removed, squeezed, dried, and heated in a vapour containing formaldehyde and methyl alcohol.  The catalysts used are (a) 20 per cent ammonium dihydrogen phosphate, (b) 10 per cent maleic acid and 30 per cent glycollic acid.  (2) Polyhexamethylene adipamide yarn is steeped in a solution of oxalic acid, dried, and heated to 100 DEG  C. in a vapour containing formaldehyde and methyl alcohol in the ratio 18 : 82.  (3) Polyhexamethylene adipamide yarn is steeped in a solution containing oxalic acid and dodecyl alcohol, dried, and heated to 100 DEG  C. in the presence of a vapour containing formaldehyde and methyl alcohol in the ratio 25 : 27.  (4) The process of (3) is repeated but using a vapour containing formaldehyde and iso-butanol in the ratio 11 : 89. (5) Polyhexamethylene adipamide yarn is steeped in a solution of oxalic acid, dried, and heated to 100 DEG  C. in a vapour containing formaldehyde and methyl alcohol in the ratio 18 : 82, and then stretched by about 100 per cent and maintained in its stretched condition for 24 hours.  (6) Monofil from the interpolyamide obtained from hexamethylene diammonium adipate, hexamethylene diammonium sebacate and epsilon-aminocaprolactam is steeped in a solution of glycollic acid, dried, and heated to 120 DEG  C. in the vapour of formaldehyde and methyl alcohol in the ratio 1 : 1.  (7) Fabric woven from a warp of viscose rayon and a weft of polyhexamethylene adipamide yarn is steeped in a solution of glycollic acid, dried, and heated to 115 DEG  C. in a vapour containing formaldehyde and methyl alcohol in the ratio 40 : 60.  (8) Fabric woven from polyhexamethylene adipamide yarn is steeped in a solution of oxalic acid, dried, and heated to 110 DEG  C. in a vapour containing formaldehyde and methyl alcohol in the ratio 25 : 75.  The mixed vapours of formaldehyde and methyl alcohol may be prepared by distilling a mixture of equal parts of paraformaldehyde and methyl alcohol until the vapours are present in the required proportion. Specifications 461,236, 461,237, 474,999, 495,790, 534,698 and 582,517 are referred to.