The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 20, 1980
Filed:
Aug. 08, 1978
Takamitsu Enomoto, Ube, JP;
Kyoji Tanaka, Ube, JP;
Hiromi Kawamoto, Onoda, JP;
Tamotsu Mizuno, Ube, JP;
Masao Fujinaga, Ube, JP;
Central Glass Company, Limited, Ube, JP;
Abstract
A process of preparing calcium hydrogen phosphate anhydride suitable as a raw material for phosphate phosphors, wherein CaHPO.sub.4.2H.sub.2 O is precipitated by mixing aqueous solutions of NaNH.sub.4 HPO.sub.4.4H.sub.2 O and CaCl.sub.2.6H.sub.2 O at 5.degree.-40.degree. C. An entire quantity of CaHPO.sub.4.2H.sub.2 O to be converted to CaHPO.sub.4 in one batch is put into an acidified water maintained above 80.degree. C. all at once. Crystalline CaHPO.sub.4 is obtained through agitation of a resultant hot slurry for a few minutes. Crystal habit of the product depends on the pH of the hot water: lozenge-shaped plates when the pH is below 3.4, parallelogram plates in the pH range of 3.4-4.4, and square or rectangular plates when the pH is above 4.4. The particle size of CaHPO.sub.4 depends on the water temperature and the degree of agitation. To precipitate CaHPO.sub.4.2H.sub.2 O in the presence of suitable quantity of seed crystals is effective for minimizing the Na content of CaHPO.sub.4.