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 (D50) 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.