초록 ▼

A transparent pigmentary form of 4,4′,7,7′-tetrachlorothioindigo is prepared by oxidizing the leuco compound of tetrachlorothioindigo in aqueous alkaline suspension, in the presence of a dithionite, at from 20°to 100°C., with simultaneous exposure to shearing forces. Preferably, the oxidation is car

A transparent pigmentary form of 4,4′,7,7′-tetrachlorothioindigo is prepared by oxidizing the leuco compound of tetrachlorothioindigo in aqueous alkaline suspension, in the presence of a dithionite, at from 20°to 100°C., with simultaneous exposure to shearing forces. Preferably, the oxidation is carried out in the presence of a surfactant. The pigment obtained gives brilliant, transparent full-shade colorations, while white reductions have a deep pure reddish hue.

대표청구항 ▼

A process for the preparation of a transparent pigmentary form of 4,4′,7,7′-tetrachlorothioindigo wherein the leuco compound of tetrachlorothioindigo is oxidized with air, hydrogen peroxide or an adduct of hydrogen peroxide with sodium carbonate or sodium borate in an aqueous suspension which contai

A process for the preparation of a transparent pigmentary form of 4,4′,7,7′-tetrachlorothioindigo wherein the leuco compound of tetrachlorothioindigo is oxidized with air, hydrogen peroxide or an adduct of hydrogen peroxide with sodium carbonate or sodium borate in an aqueous suspension which contains from 3 to 20% by weight, based on the suspension, of leuco compound and from 0.5 to 50% by weight of alkali metal hydroxide and from 1 to 10% by weight of sodium dithionite, both based on leuco compound, at from 20°to 100°C., with simultaneous grinding in the presence of a grinding medium until the leuco compound is completely oxidized, and the pigment is isolated.