| 摘要 |
Titanium oxide pigments (including composite pigments containing calcium or barium sulphate, whiting, silica, or clay) are improved by incorporating in them up to 5 per cent of lead titanate. Lead titanate may be mixed directly with a titanium pigment, or the titanium pigment may be heated with a lead compound such as the oxide, basic carbonate or sulphate to 500--900 DEG C., lead titanate being formed on the titanium oxide particles. The lead compound may be added to a finished titanium pigment, or to the freshly precipitated pigment, either as such or by carrying out the washing for removal of sulphuric acid with lead chloride. Salts such as sodium sulphate, phosphate, or carbonate may be added before the heating step to facilitate crystallization of the titanium oxide. Specification 113,790, [Class 95, Paints, &c.], is referred to. The Specification as open to inspection under Sect. 91 describes also pigments produced by heating titanium pigments with lead compounds in any proportions up to the chemical equivalent of the titanium present. This subject-matter does not appear in the Specification as accepted.
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