Patent GB-460201-A (GB)
Title: Improvements in the finishing of textile materials
IPC: D06M13/12
Filed: 1935-07-22
Abstract: Fabrics of vegetable origin are rendered crease-resisting and shrink-resisting and effects thereon such as dyeing or mechanical effects rendered fast to washing, by impregnation with formaldehyde or a compound yielding formaldehyde and with an oxidizing acid, drying, heating, washing and drying.  A phenolic or amidic compound capable of condensing with the formaldehyde must not be present.  The oxidizing acid may be nitric, perchloric, persulphuric, or a salt thereof, or a compound which will liberate one of these acids during heat treatment.  The formaldehyde solution has a strength of 10--20 per cent, and the heat treatment is preferably at 180--200 DEG  C. for about 2 mins. to 50 seconds.  The formaldehyde may be replaced by analogous compounds such as glyoxal.  To the impregnating solution may be added a dyestuff which normally has little or no affinity for the fabric or which normally will not give dyeings fast to washing. Other effects which may be fixed by the treatment are embossing, glazing, scheinering; pigments may be added to the solution.  Thus the fabric may be impregnated with formaldehyde and acid, dried, printed with an alkaline paste, subjected to a mechanical finishing treatment, heated, washed and dried; the fabric may then be dyed with a direct dyestuff, or a dyestuff may be added to the alkaline paste, or the fabric may be dyed with a fugitive dyestuff previous to its treatment with the formaldehyde.  To counteract the tendering action of the acid, protecting agents may be added to the bath or applied to the fabric before impregnating, e.g. natural gums, sodium metaphosphate, aluminium hydroxide or hexamethylene tetramine.  In examples: (1) a viscose taffeta cloth is treated with a solution of aluminium acetate, dried and steamed; it is then impregnated with a solution containing 16 per cent formaldehyde and ,2 per cent nitric acid, dried and heated to 200 DEG  C., for 50 seconds.  It is finally washed in ,05 per cent sodium carbonate at 60 DEG  C. for 10 minutes, and in boiling soap solution for 5 mins.  The fabric is crease-resisting.  (2) A viscose taffeta cloth is printed with a 10 per cent zinc oxide paste using gum dragon as thickening agent, dried, impregnated with a solution containing 38 per cent formaldehyde and ,4 per cent nitric acid, dried and heated to 180 DEG C. for 2 mins.  After washing off as in Example 1, the product shows a mat print on a lustrous ground.  (3) A viscose taffeta cloth previously dyed with 2 per cent Chlorazol Fast Red K is impregnated with a solution containing 15 per cent formaldehyde, 2 per cent ammonium perchlorate, 2,5 per cent sodium hexametaphosphate, dried, heated to 200 DEG  C. for 50 secs. and washed off as in example 1. The colour is rendered fast to boiling soap solution.  (4) A viscose taffeta cloth is impregnated with a solution containing 15 per cent formaldehyde, 2 per cent olein oil, and 2 per cent ammonium persulphate, dried, conditioned, embossed, heated to 200 DEG  C. for 50 secs. and washed off as in example 1.  The embossing is completely fast to washing and ironing.  (5) A viscose taffeta is impregnated with a solution containing 15 per cent formaldehyde, ,5 per cent ammonium persulphate, ,125 per cent hexamethylene tetramine and 2 per cent Lissamine Fast Yellow 2G, dried and printed with a paste containing 5 per cent Soledon Brilliant Purple RR paste, 2 per cent pyridine, 2 per cent sodium carbonate, and gum dragon as thickening, dried, heated to 200 DEG  C. for 50 secs., and developed for 2 mins. in a solution containing 3 per cent sodium bichromate and 2 per cent of 96 per cent sulphuric acid, rinsed in a cold sodium carbonate solution and washed off as in example 1.  The effect is a purple print on a yellow ground.