GB512607A - Improvements in production of organic pigments - Google Patents

Abstract

512,607. Pigments ; dyeing textiles ; artificial silk. TOOTAL BROADHURST LEE CO., Ltd., FOULDS, R. P., and JOHNSON, R. N. Dec. 9, 1937, No. 34053. [Classes 2 (ii), 2 (iii) and 15 (ii)] Coloured-pigments are produced by dyeing a non-resinous precipitate as used in Specification 484,901 and obtained at a temperature not exceeding 60‹C., after it has been precipated. The non-resinous precipitate is the insoluble reaction' product of an aldehyde with urea or ammonium cyanate, thiourea, substituted ureas or urea-like substances, e.g., cyanamide, guanidine or semi-carbazide or bodies containing a similar NCN grouping, there being at least one free hydrogen atom attached to one of the nitrogen-atoms and including tantomeric forms of the substances capable of reacting with an aldehyde in the presence of a precipitant to form a non- resinous precipitate (but excluding ' aminotriazines). The non-resinous precipitate may be formed in the presence of an emulsifying, dispersing or protective agent as described in Specification 484,901. The coloured pigments may be used in the treatment of textile materials as described in Specification 484,901, by simple application or'by incorporation in artificial silk solutions before spinning. The precipitates may be dyed with vat, naphthol azo, sulphoricinoleic acid or other colours used for dyeing cellulose acetate artificial silks, direct, basic or acid colours. In examples (1) urea and aqueous formaldehyde are mixed, aqueous tartaric acid solution added, the whole allowed to stand and the precipitate filtered off, washed and dried ; the precipitate is dyed by immersing in a dye bath containing Indanthrene brilliant orange G.K., sodium hydrosulphite and caustic soda ; (2) semicarbazide hydrochloride is dissolved in water, aqueous -formaldehyde added, the mixture stirred to complete precipitation and the precipitate filtered off; it is dyed by immersion in a bath containing Caledon yellow paste, sodium hydrosulphite and caustic soda ; (3) a cotton fabric is padded with a solution of methyl or glycol cellulose in sodium hydroxide to which a dyed pigment has been added ; the fabric is then partially dried at a low temperature or treated with acid, it can be further treated by means of a hot calender. Specifications 435,767 and 487,835 also are referred to. In the Provisional Specification the pigments are obtained by colouring or simultaneously colouring and producing the insoluble non-resinous reaction products. A mixture of urea and formaldehyde may be added to the dye bath under non-acid conditions and precipitation effected by addition of acid in presence of the dye. The pigments can be used for incorporation with material used for making linoleum, resin blocks, paints and distempers.