Cerium/rare earth polishing compositions
AssigneeRhone-Poulenc Specialites Chimiques
InventorsPierre Melard, Francis Tastu
Life of this patent
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Abstract
Glass polishing compositions, advantageously recycled into glassmaking formulations, are comprised of suspension of particulate ceric oxide and at least one colorless oxide of a lanthanide or yttrium rare earth, preferably an oxide of lanthanum, samarium, europium, gadolinium, dysprosium, thulium, ytterbium, lutecium, yttrium, or mixtures thereof.
Claims86
A process for the preparation of a polishing composition of matter, consisting essentially of (i) simultaneously and continuously intimately admixing a solution of a cerium salt that comprises an aqueous solution of at least one of cerous chloride, cerous nitrate, and ceric nitrate, a basic solution selected from the group consisting of ammonia, sodium or potassium hydroxide and a solution of at least one salt of a trivalent lanthanide or yttrium rare earth, the oxide of which is colorless, with the number of equivalents of base being at least equal to the number of equivalents of cerium and rare earth values and the pH of the reaction medium being greater than 6, (ii) filtering the precipitate which results, (iii) drying said precipitate, and (iv) thence calcining said precipitate.
A polishing composition capable of being recycled into glass, provided by a process consisting essentially of (i) simultaneously and continuously intimately admixing a solution of a cerium salt, a basic solution selected from the group consisting of ammonia, sodium or potassium hydroxide and a solution of at least one salt of a trivalent lanthanide or yttrium rare earth, the oxide of which is colorless, with the number of equivalents of base being at least equal to the number of equivalents of cerium and rare earth values and the pH of the reaction medium being greater than 6, (ii) filtering the precipitate which results, (iii) drying said precipitate, and (iv) thence calcining said precipitate.
Dependencies are inferred from the claim text.