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. 10, 2022
Filed:
Dec. 22, 2017
Kao Corporation, Tokyo, JP;
Tomohide Yoshida, Nakayama, JP;
Yasufumi Ueda, Nakayama, JP;
KAO CORPORATION, Tokyo, JP;
Abstract
The present invention relates to a process for producing a dispersion of white fine particles from which a white ink that is capable of exhibiting excellent hiding power, rub fastness and water resistance even when printed on a low-water absorbing printing medium can be obtained by incorporating the dispersion of the white fine particles into the ink, and a water-based ink for ink-jet printing which contains the white fine particles. The present invention provides [1] a process for producing a dispersion of white fine particles, including step 1 of mixing titanium oxide and a polymer dispersant at a pH value that is not less than an acid dissociation exponent (pKa) of at least a part of an acid component of the polymer dispersant to thereby obtain a titanium oxide dispersion, in which an isoelectric point (A) of the titanium oxide and the acid dissociation exponent (pKa) (B) of the polymer dispersant satisfy a relationship represented by the formula: A−B≥0, the polymer dispersant contains a constitutional unit derived from a hydrophobic monomer, and a volume median particle size (D) of particles in the titanium oxide dispersion is from 150 to 500 nm; and step 2 of adding a polymerizable monomer to the titanium oxide dispersion obtained in the step 1 to subject the polymerizable monomer to polymerization reaction, thereby obtaining the dispersion of the white fine particles, and [2] a water-based ink for ink-jet printing which contains the white fine particles obtained above.