GB250251A - Manufacture of vat-dyestuff preparations - Google Patents

Abstract

250,251. Soc. of Chemical Industry in Basle. April 2, 1925, [Convention date]. Dye preparations.-Preparations of vat dyestuffs in solid form are prepared by intimately mixing the dyestuff with a non-caustic alkali such as alkali carbonate, borate or phosphate, and with a hydrosulphite, a dispersing-agent such as turkey red oil or sulphite cellulose lye being added if necessary. For example, the dyestuff paste is first mixed with the dispersing-agent, the non- caustic alkali is then added and the mixture evaporated to dryness; the hydrosulphite is incorporated after the product has been finely ground. The preparations dissolve easily in water, forming vats particularly suitable for wool dyeing. In examples, a preparation is made by grinding together in the moist state 2: 5-dianilido-1 : 4- benzoquinone, soda ash or its equivalent, and monopol soap solution, then evaporating the mixture to dryness, grinding, and mixing with sodium hydrosulphite; the brown dyestuff from sulphur chloride and 2: 5-dianilidobenzoquinone prepared as described in Specification 237,375 either alone or mixed with indigo, is incorporated with soda ash or potassium carbonate, monopol soap solution and sulphite cellulose lye, the mixture is then evaporated to dryness and ground, and finally mixed with sodium hydrosulphite; tetrabromindigo, soda ash, sodium hydrosulphite and sulphite cellulose lye are finely ground together; thioindigo, soda ash, and monopol soap solution are made into a paste, then dried and mixed with sodium hydrosulphite. Other dyestuffs or mixtures of dyestuff may be employed; thus there may be used dianilidoquinone and 2-thionaphthene-acenaphthene-indigo or a mixture of dianilidoquinone and indirubin. In the Specification as open to inspection under Sect. 91 (3) (a) the preparation from 2 : 5-dianilido-1 : 4-benzoquinone is made up with sulphite cellulose lye in addition to the monopol soap solution; in the preparations from the brown dyestuff described in Specification 237,375, the sulphite cellulose lye is omitted: and monopol soap solution is used in addition to sulphite cellulose lye in the preparation from tetrabromindigo. This subject-matter does not appear in the Specification as accepted.