| 摘要 |
<p>Iron oxide pigments containing manganese in solid solution and having a uniform haematite structure are prepared by a process of oxidizing metallic iron with an aromatic nitro compound in the presence of manganese metal or a manganese compound (see Division C1), black pigments being produced when the weight ratio of Fe: Mn is from 14: 1 to 5: 1 and reddish brown to brown pigments when the ratio is from 100: 1 to 15: 1.ALSO:Iron oxide pigments containing manganese and having a uniform haematite structure are produced by oxidizing metallic iron with an aromatic nitro compound at a pH of 3.5 to 6.5 in the presence of manganese metal or a manganese compound and an aqueous ferrous salt solution, and/or a concentrated aqueous solution of a salt which can be hydrolysed or an aqueous suspension of a difficultly water soluble oxide, hydroxide, or basic salt of a trivalent or tetravalent metal, or phosphoric acid, or a dissolved or suspended lead compound, or iron oxide or hydroxide nuclei obtained from yellow, reddish brown or red iron hydroxides or oxides, and working up the resulting pigment sludge by filtering, washing and calcining at 600 DEG to 800 DEG C. The pigments produced consist of a solid solution of alpha-Mn2O3 and alpha-Fe2O3. Reddish brown to brown pigments are formed if the weight ratio of iron to manganese is from 100:1 to 15:1 and black pigments when the ratio is from 14:1 to 5:1. Specified manganese sources are manganese alloys, MnCl2, MnSO4, Mn(OCOCH3)2, pyrolusite and rhodochrosite.</p> |
