method of preparing aqueous dispersion of opacifying polymer particles, aqueous dispersion of opacifying polymer particles, dried aqueous dispersion particles, coating composition, and substrate equipped with a coating composition

摘要

method of preparing aqueous dispersion of opacifying polymer particles, aqueous dispersion of opacifying polymer particles, dry particles of aqueous dispersion, coating composition, and substrate equipped with a coating composition method of preparing aqueous dispersion of opacifying polymer particles containing particles of inorganic pigment therein, comprising or consisting of the steps of: i. dispersion of inorganic pigment in aqueous medium using an acid dispersant of at least 65 mg koh / g dispersant, wherein the dispersant comprises acidic portions and the ph during dispersion is greater than the acidic portion pka and also at least 0.25 ph units above or below the isoelectric point of the pigment particles to form a stable aqueous pigment dispersion in the aqueous medium; ii. adjusting the pigment dispersion ph below the pka of the acid moieties comprising the expandable base polymer of step iii while meeting the ph criteria of step i; iii. forming a first layer of an expandable base polymer on the pigment particles by polymerizing acidic monomers; iv. forming a second polymer layer other than expandable base; v. optional polymerization of additional monomers to form intermediate polymer layers having an acid value of 0 to 65 mg koh / g polymer between the pigment and the first layer and / or between the first and the second layer; saw. at least partially neutralizing the expandable base polymer using a base at a temperature above the effective tg of the non-expandable base polymer such that the expandable base polymer is forced to expand; and vii. cooling the opacifying polymer particle dispersion to a temperature below the effective tg of the polymer other than expandable base. 1/2