LEAD MONOXIDE

摘要

1509103 Lead monoxide MIZUSAWA KAGAKU KOGYO KK 13 May 1976 19804/76 Heading C1A The invention relates to a novel lead monoxide having a pycnometric density of 8À5 to 9À2 g./cc., a primary particle size not larger than 0À2 Ám, an infrared absorption peak at a wave number of 1400 to 1410 cm-1 and a chromic anhydride reactivity, as defined, of at least 94%. The monoxide may be the "litharge" type of density 8À80 to 9À17 g/c.c., the massicot type of density 8À35 to 9À2 g/c.c. or the hydrate type of lead monoxide of density 8À80 to 9À10 g/c.c. and having a hydrate water content of 0À2 to 0À8 mole per mole PbO, each form having a primary particle size of 0À01 to 0À05 Ám and characterized by their respective X-ray diffraction pattern. A process is also described for preparing the lead monoxides by charging metallic lead, a liquid medium inert to metallic lead and lead monoxide and CO 2 -free oxygen gas to a rotary mill, rotating the mill so that at least part of the metallic lead granules wetted with the liquid medium are located temporarily in the oxygen above the level of the liquid medium and thereby forming a thin lead monoxide coating on the lead granules and grinding the oxide-coated metallic granules in the liquid medium to form by friction therein a dispersion of very fine particles of lead monoxide in the medium, separating the dispersion from the metallic lead granules to yield, if desired, the lead monoxide in a fine powder form. The process may be conducted continuously or batchwise; preferred ranges for the ratios of solid lead/liquid medium; the volume of oxygen/volume of liquid medium, and the bulk volume of the lead/total volume of the mill are claimed. The rate of rotation of the mill is preferably 20-150% of a critical rotation number, as defined. The liquid medium may be a polar or non-polar organic solvent or an aqueous medium and the process may be conducted at an O 2 pressure of at least 0À2 Kg/cm2 (absolute) in the range of -5‹ to 70‹C