| abstract |
A water-dispersible powder or paste preparation of a water-insoluble dye contains at least one sodium salt of a water-soluble condensation product of (I) a naphthalene monosulphonic acid or derivative thereof and formaldehyde or (II) a mononuclear aromatic compound capable of reacting with 2 moles of formaldehyde, a napthol sulphonic acid, formaldehyde and optionally sodium sulphite, the content of inorganic salt in said preparation being less than 5%, preferably 0.5% by weight of compound (I) or (II). Products (I) and (II) may be prepared free from salts from the start by a conventional method or the conventional industrial product may be freed from salts by dialysis, ion exchange, electrolysis or precipitation with organic liquids. The preparations may also contain urea or thiourea as dispersion assistants. Suitable dyes are vat or disperse dyes. The preparations may be prepared by grinding, kneading or spray drying. Suitable products (I) and (II) are specified and examples are given. |