Process for controlling adsorption of polymeric latex on titanium dioxide
AssigneeRohm and Haas Company
InventorsWilliam D. Emmons, William C. Finch, Meredith A. Morgan
Life of this patent
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Abstract
Coatings compositions including stable composite latex-pigment particles are prepared by dispersing titanium dioxide pigment particles in a first aqueous medium and preparing a dispersion of selected polymeric latex particles, which have at least one dihydrogen phosphate functional group, in a second aqueous medium. The media are mixed and the selected polymeric latex particles adsorb on the titanium dioxide particles. Dibasic phosphate is then provided to the mixture to stop adsorption and stabilize the composite particles. The coating composition gives a coating with improved hiding.
Claims21
A process for preparing an aqueous dispersion including selected polymeric latex particles and titanium dioxide pigment particles and for controlling the adsorption of the selected polymeric latex particles on the titanium dioxide particles, the process comprising:
- a) dispersing titanium dioxide pigment particles in a first aqueous medium;
- b) preparing a dispersion or suspension of selected polymeric latex particles in a second aqueous medium, the selected polymeric latex particles having at least one dihydrogen phosphate functional group;
- c) mixing the aqueous media containing the titanium dioxide pigment particles and the selected polymeric latex particles;
- d) permitting the selected polymeric latex particles to adsorb on the titanium dioxide particles to form composite particles, the composite particles not comprising a continuous layer of polymer enveloping the surface of the respective titanium dioxide particles;
- and
- e) then providing an effective amount of dibasic phosphate to the mixture of selected polymeric latex particles and titanium dioxide particles.
A process for preparing an aqueous dispersion including selected polymeric latex particles and titanium dioxide pigment particles and for controlling the adsorption of the selected polymeric latex particles on the titanium dioxide particles, the process comprising:
- a) preparing a dispersion or suspension of selected polymeric latex particles in an aqueous medium, the selected polymeric latex particles having at least one dihydrogen phosphate functional group;
- b) dispersing titanium dioxide pigment particles in the aqueous medium;
- c) permitting the selected polymeric latex particles to adsorb on the titanium dioxide particles to a predetermined extent to form composite particles, the composite particles not comprising a continuous layer of polymer enveloping the surface of the respective titanium dioxide particles;
- and
- d) then providing an effective amount of dibasic phosphate to the mixture of selected polymer latex particles and titanium dioxide particles.
A process for preparing an aqueous dispersion including selected polymeric latex particles and titanium dioxide pigment particles and for controlling the adsorption of the selected polymeric latex particles on the titanium dioxide particles, the process comprising:
- a) dispersing titanium dioxide pigment particles in a first aqueous medium;
- b) preparing a dispersion or suspension of selected polymeric latex particles in a second aqueous medium, the selected polymeric latex particles having at least one dihydrogen phosphate functional group;
- c) mixing the aqueous media containing the titanium dioxide pigment particles and the selected polymeric latex particles;
- d) permitting the selected polymeric latex particles to adsorb on the titanium dioxide particles to form composite particles, the composite particles not comprising a continuous layer of polymer enveloping the surface of the respective titanium dioxide particles;
- and
- e) then providing an effective amount of dibasic phosphate to the mixture of selected polymeric latex particles and titanium dioxide particles, the phosphate salt being provided at least about ten minutes after first mixing the aqueous media containing the titanium dioxide pigment particles and the selected polymeric latex particles.
A process for preparing an aqueous dispersion including selected polymeric latex particles and titanium dioxide pigment particles and for controlling the adsorption of the selected polymeric latex particles on the titanium dioxide particles, the process comprising:
- a) preparing a dispersion or suspension of selected polymeric latex particles in an aqueous medium, the selected polymeric latex particles having at least one dihydrogen phosphate functional group;
- b) dispersing titanium dioxide pigment particles in the aqueous medium;
- c) permitting the selected polymeric latex particles to adsorb on the titanium dioxide particles to a predetermined extent to form composite particles, the composite particles not comprising a continuous layer of polymer enveloping the surface of the respective titanium dioxide particles;
- and
- d) then providing an effective amount of dibasic phosphate to the mixture of selected polymer latex particles and titanium dioxide particles, the phosphate salt being provided at least about ten minutes after the titanium dioxide pigment particles are first dispersed in the aqueous media containing the selected polymeric latex particles.
Dependencies are inferred from the claim text.