Heat stable yellow iron oxides containing antimony

The preparation of a heat stable yellow iron oxide pigment comprising:

• (a) forming an aqueous dispersion of yellow iron oxide (.alpha.-FeOOH), the dispersion having the approximate composition of about 30 to about 200 parts yellow iron oxide per 1,000 parts water,
• (b) adding thereto an aqueous alkaline solution of a soluble compound of antimony from the group consisting of sodium antimonite, potassium antimonite, SbCl.sub.3, SbF.sub.3 and Sb.sub.2 (SO.sub.4).sub.3, the solution having the approximate composition of the antimony equivalent of about 0.3 to 20 parts antimony trioxide, about 40 to 80 parts alkali metal hydroxide, and about 400 parts water,
• (c) diluting the resultant mixture, the diluting volume ranging from about 1.2 to about 5 volumes per original volume of mixture,
• (d) separating the resultant product into a solid phase and an aqueous phase,
• (e) forming an aqueous dispersion of the solid phase, the dispersion having the approximate composition of about 200 parts solid phase per 1,000 parts water,
• (f) subjecting the dispersion to a hydrothermal treatment, at a temperature of from about 100.degree. C. to about 350.degree. C., for a time greater than 1/2 hour, and
• (g) recovering the solid product of treatment.

The preparation of a heat stable yellow iron oxide pigment, comprising:

• (a) forming an aqueous slurry of yellow iron oxide (.alpha.-FeOOH), a soluble ferric salt selected from the group consisting of ferric chloride, ferric nitrate, ferric oxalate, and ferric thiocyanate, an alkali metal hydroxide, and a soluble compound of antimony from the group consisting of sodium antimonite, potassium antimonite, SbCl.sub.3, SbF.sub.3 and Sb.sub.2 (SO.sub.4).sub.3, with the approximate composition of the slurry being about 30 to 200 parts yellow iron oxide, from about 1 to about 100 parts ferric salt, about 20 to 100 parts of the antimony equivalent of antimony trioxide, and about 5 to 15 parts alkali metal hydroxide for each part of antimony trioxide used, per 1,000 parts water,
• (b) subjecting the resultant mixture to a hydrothermal treatment carried out at a temperature of from about 100.degree. C. to about 240.degree. C., for a time greater than 1/2 hour,
• (c) separating the resultant product into a solid phase and a liquid phase, and
• (d) recovering the solid phase.

The preparation of a heat stable yellow iron oxide pigment comprising:

• (a) forming an aqueous alkaline dispersion of about 30 to about 200 parts of yellow iron oxide (.alpha.-FeOOH) in 1,000 parts of an aqueous solution of an alkali metal hydroxide having a concentration of greater than 0.1 N and less than 10 N,
• (b) subjecting the alkaline dispersion to a first hydrothermal treatment, at a temperature of from about 100.degree. C. to about 240.degree. C., for a time greater than 1/2 hour,
• (c) separating the resultant product into a solid phase and an aqueous phase,
• (d) adding about 500 parts of water to the solid phase to form an aqueous dispersion,
• (e) adding to the aqueous dispersion an aqueous alkaline solution of a soluble compound of antimony from the group consisting of sodium antimonite, potassium antimonite, SbCl.sub.3, SbF.sub.3 and Sb.sub.2 (SO.sub.4).sub.3, the alkaline solution having the antimony equivalent of about 0.03 to 20 parts antimony oxide, about 40 to 80 parts alkali metal hydroxide, and about 400 parts water,
• (f) diluting the resultant mixture,
• (g) separating the diluted dispersion into a solid phase and an aqueous phase and then recovering the solid phase,
• (h) adding to the solid phase about 200 to about 400 parts water and subjecting the resultant dispersion to a second hydrothermal treatment at a temperature of from about 100.degree. C. to about 350.degree. C., for a time greater than 1/2 hour,
• (i) separating the product of the treatment into a solid phase and an aqueous phase, and
• (j) recovering the solid phase.

The preparation of a heat stable yellow iron oxide pigment, comprising:

• (a) forming a dispersion of about 30 to 200 parts yellow iron oxide (.alpha.-FeOOH) in about 1,000 parts of an aqueous solution of an alkali metal hydroxide having a concentration of greater than 0.1 N and less than 10 N,
• (b) subjecting this dispersion to a first hydrothermal treatment at a temperature of from about 100.degree. C. to about 240.degree. C., for a time greater than 1/2 hour,
• (c) separating the treated product into a solid phase and an aqueous phase,
• (d) forming a second dispersion of the solid phase from step (c) by adding thereto an aqueous solution of ferric sulfate, an aqueous alkaline solution of a soluble compound of antimony from the group consisting of sodium antimonite, potassium antimonite, SbCl.sub.3, SbF.sub.3 and Sb.sub.2 (SO.sub.4).sub.3, and an aqueous solution of an alkali metal silicate or an alkali metal stannate, the dispersion having the approximate composition of from about 35 to about 200 parts solid phase, from about 1 to about 100 parts ferric sulfate, the antimony equivalent from about 20 to about 100 parts antimony trioxide, from about 5 to about 15 parts alkali metal hydroxide for each part of antimony trioxide used, and from about 0.3 to about 5 parts alkali metal silicate or alkali metal stannate, per 1,000 parts water,
• (e) subjecting the resultant dispersion to a second hydrothermal treatment, at a temperature of from about 100.degree. C. to about 350.degree. C., for a time greater than 1/2 hour,
• (f) separating the treated product into a solid phase and a liquid phase, and
• (g) recovering the solid phase.