| abstract |
A process for producing a sulfonated solid particle selected from the group consisting of organic pigments, fine carbon black particles, water-insoluble paints and fine resin particles, said process comprising the steps of: (a) burning sulfur to gaseous sulfur dioxide, (b) catalytically oxidizing the gaseous sulfur dioxide to gaseous sulfur trioxide, and (c) sulfonating a dry powdered or granular solid particle with the gaseous sulfur trioxide in a gas phase solid phase reaction at a temperature in the range of 80 to 130 ° C for 1 to 6 hours, wherein a gaseous mixture of the gaseous sulfur trioxide with a gaseous sulfur trioxide and the solid particle inert gas is used in the sulfonation step. |