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:
Feb. 06, 2001
Filed:
Aug. 06, 1999
Yoshiharu Shimokawa, Yokohama, JP;
Osamu Ishizu, Kawasaki, JP;
Nippon Zeon Co., Ltd., Tokyo, JP;
Abstract
Bowl-shaped polymer particles characterised by having a bowl-like shape as is formed by partly cutting along a plane each spherical hollow polymer particle having a void in the inside, and in which the cross-section perpendicular to the cut plane and passing through the center of the particle has a shape as is formed by partly cutting a double circle along a straight line, and the lengths H of the perpendiculars from the outer arc of the double circle in the cross-section to the straight line have a maximum value H,equal to or larger than the radius of the outer circle of the double circle. The bowl-shaped polymer particles have a multi-layer structure, and are produced by multi-stage polymerization in which monomer mixtures are successively polymerized in a manner such that the proportion of a monomer having an acidic group gradationally decreases and by treating the resultant polymer with a base. The bowl-shaped polymer particles are useful as a heat-insulating material, organic pigment, or opacifying agent, and especially as a heat-insulating interlayer to be formed in a thermal recording material.