GB440594A - Improvements in or relating to the colouration of textile materials - Google Patents

Abstract

Mordant dyes, dyeing with; cellulose esters or ethers, dyeing; printing.--Textile materials made of or containing cellulose esters or ethers are coloured by applying thereto a natural dyestuff capable of being fixed by afterchroming and thereafter chroming in a chromate bath containing one or more of the following assistants, viz. oxalic acid, an oxalate, an alkali metal sulphite or ammonium thiocyanate. The materials, so coloured in pale shades, may be coloured in dark shades by topping with another dyestuff. Specified natural dyestuffs are logwood, haematein, fustic, young fustic, quercitron, Persian berries, weld extract, sandalwood and cutch. The shades of the dyeings may be varied or their fastness improved by incorporating with the natural dyestuffs, metal compounds such as magnesium sulphate, calcium chloride, calcium hydroxide, lead acetate or calcium acetate. Delustring agents, such as titanium dioxide or antimony trioxide, present in the materials may also modify the shade. The following examples are specified: (1) A cellulose acetate material is dyed blue-grey by treatment for 1 hour with a logwood solution at 80 DEG C. followed by treatment for \ba1/2\be hour with a solution at 60 DEG C. containing sodium bichromate and sodium oxalate; the dyeing may be topped with a direct dye or with logwood or other natural dyestuff; a deep black dyeing may be obtained by topping with a mixture of yellow, orange and red dyestuffs having affinity for cellulose acetate; (2) A mixed natural silk-cellulose acetate material, delustred with titanium oxide, is dyed a greenish black by immersing for 1 hour in a solution at 80 DEG C. containing logwood and cutch, followed by chroming in a bath containing sodium bichromate and sodium oxalate; (3) A cellulose acetate fabric is dyed a deep delustred black by treatment for 1 hour with a logwood solution at 80 DEG C. followed by rinsing, chroming for \ba1/2\be hour with a solution at 70--75 DEG C. containing sodium bichromate and sodium oxalate, rinsing and scouring with soap. A table is also given showing the shades, ranging from light grey to deep black, obtainable on a cellulose acetate woven fabric with various strengths of logwood solution at 80 DEG C. and various strengths of sodium bichromate solution at 60 DEG C. containing oxalic acid. The application to printing is exemplified by the printing of an aqueous paste containing haematein, glycerol and glucose, British gum or gum tragacanth upon a mixed fabric containing a cellulose ester or ether and silk, the printed fabric being steamed, chromed with a solution containing sodium bichromate and sodium oxalate, rinsed and soaped.