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:
Jan. 18, 2000
Filed:
Aug. 23, 1996
Takeshi Fukuda, Kurobe, JP;
Ryuichi Shido, Kurobe, JP;
YKK Corporation, Tokyo, JP;
Abstract
Alumina particles having high dispersibility and plasticity, at least on the surface of which a phosphoric acid or phosphate is present and suitable for use as a material for pigments for paints, precision abrasives or ceramics. The alumina particles are produced by adding a crystallization inhibitor containing at least phosphate ion to aluminum hydroxide or alumina hydrate and then conducting a hydrothermal synthesis treatment. The amount of the phosphate ion to be added is in the range of 3.0.times.10.sup.-3 to 2.5.times.10.sup.-2 mol per mol of aluminum hydroxide or alumina hydrate. The particle size of aluminum hydroxide or alumina hydrate is 0.1 to 5.0 .mu.m. The hydrothermal synthesis is preferably conducted at 350.degree. C. or above under a pressure of 50 to 200 atm and at a temperature elevation rate of 50.degree. C./min to 0.3.degree. C./min. The thus obtained alumina is .alpha.-alumina in the form of hexagonal plate single crystal having a particle size of 0.2 to 15 .mu.m, an aspect ratio of 15 to 50 and an isoelectric point at which the zeta-potential is 0 of pH 4 to 8.