United States Patent (19) 11 Patent Number: 4,601,755 Mélard Et Al
United States Patent (19) 11 Patent Number: 4,601,755 Mélard et al. 45 Date of Patent: Jul. 22, 1986 (54) CERIUM BASED GLASSPOLISHING (56) References Cited COMPOSITIONS U.S. PATENT DOCUMENTS 75 Inventors: Pierre Mélard, Lagord; Marcel 3,262,766 7/1966 Nonamaker ........... ... 51/309 Peltier, La Rochelle; Francis Tastu, 3,768,989 10/1973 Goetzinger et 51/309 Nieul/sur/Mer, all of France 4,161,463 7/1979 Myers et al... ... SO2/263 73 Assignee: Rhone-Poulene Specialites 4,62,921 7/1979 Litvinov et al. P ... O - 0 - - - - - - - - - - - A as - - 50/9 Chimiques, Courbevoie, France Primary Examiner-Amelia B. Yarbrough Attorney, Agent, or Firm-Burns, Doane, Swecker & 21 Appl. No.: 635,828 Mathis 22 Filed: Jul, 30, 1984 57 ABSTRACT (30) Foreign Application Priority Data Cerium based glass polishing compositions, well adapted for the polishing, e.g., of optical glass, are com Jul. 29, 1983 FR France ................................ 83 2519 prised of (i) at least one crystalline phase of CeO2 type, 51) Int. Cl'................................................ C09G 1/02 and (ii) a crystalline phase which comprises a rare earth 52 U.S. C. ........................................ 106/3; 51/308; pyrosilicate having the formula Ln2-CeSi2O7, 51/309; 156/DIG. 63; 423/263 wherein Ln is at least one lanthanide or yttrium and x is 58 Field of Search ................... 106/3, 288 B, 287.34; a number ranging from zero to less than 2. 51/309, 308; 423/263; 156/DIG. 63; 502/263, 302, 304,303 59 Claims, No Drawings 4,601,755 1. 2 forming insoluble rare earth compounds, with the num CERIUM BASED GLASS POLISHING ber of equivalents of base being greater than or equal to COMPOSITIONS the number of equivalents of cerium and the pH of the reaction medium being higher than 6; BACKGROUND OF THE INVENTION 5 (b) the resultant precipitate is filtered; 1.
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