GB669720A - Process for dyeing moulded articles having a basis of an organic derivative of cellulose - Google Patents

Abstract

Moulded articles having a basis of an organic derivative of cellulose are coloured by immersion in an aqueous dispersion of a dye, said dispersion also containing a soap and a water-soluble mono-alkyl ether of ethylene glycol or diethylene glycol. Suitable ethers are the methyl, ethyl, propyl and butyl ethers. The preferred ethers are ethylene glycol monobutyl ether or diethylene glycol mono-ethyl ether. They are used in the bath in amounts 5-10 per cent by weight together with 0.1 to 0.3 per cent of a soap. In addition 0.1 to 0.3 per cent of an emulsifying agent such as Turkey Red oil may be added to the bath. The dyeing temperature is preferably 25-75 DEG C. the time of immersion being from 30 seconds to 2 minutes. The depth of dyeing is from about 100 to 500 microns. By addition of film-forming compounds to the dyebath (such as polymethyl vinyl ketone, polyvinyl alcohol and methyl cellulose) an improved gloss is produced on the articles. Suitable dyestuffs include 1 : 4 : 5 : 8-tetramino-anthraquinone, 1 - amino - 4 - hydroxy - anthraquinone, 2-nitro - 4 - sulphonamido - diphenylamine, 4-nitro - phenyl - azo - 21 - methyl - 41 - di-(hydroxyethyl) - amino-benzene, and 4-acetylamino - benzene - azo - 21 - hydroxy - 51-methyl benzene, and they are used in amounts from 0.1 to 2 per cent by weight. Lignin sulphonate may be used as a dispersing agent. The cellulose derivative may be an ester such as the acetate, propionate, butyrate, acetate-propionate or acetate-butyrate, or an ether such as ethyl or benzyl cellulose. Suitable plasticizers may be incorporated in amounts from 20 to 40 per cent in the derivative, examples being dimethyl phthalate, ethyl-phthalyl-ethyl-glycollate, triethylene glycol, triphenyl phosphate, tricresylphosphate, diethyl phthalate, di-(methoxy-ethyl)-phthalate, dibutyl phthalate, triacetin, tripropionin, mineral oil, butyl stearate or partially hydrogenated terphenyls. In an example (all parts by weight) a dyebath containing 1 part of a soap, 3 parts of Turkey Red oil, 90 parts of the monobutyl ether of ethylene glycol, 6 parts of a dyestuff disperse powder of 1 : 4 : 5 : 8-tetramino-anthraquinone and 900 parts of water is heated to 40 DEG C. Moulded cellulose acetate buttons containing 30 per cent of diethylphthalate are tumbled therein for 1 minute, washed and dried.