# US 8,772,372 B2 · Method of making a pigment dispersion > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,372 B2 - Document ID: US8772372B2 - Status: Granted - Kind: B2 - Application number: 12/572,429 - Filed: 2009-10-02 - Published: 2011-04-07 - Granted: 2014-07-08 - Earliest claimed: 2009-10-02 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Sivapackia Ganapathiappan; Howard S. Tom; Hou T. Ng - Inventors: Sivapackia Ganapathiappan; Howard S. Tom; Hou T. Ng - Web page: https://patentgrep.com/patent/US8772372B2 ## CPC - C09C 3/10: Treatment with macromolecular organic compounds {(C09C3/006 takes precedence)} - C08K 9/10: Encapsulated ingredients - C09C 1/56: Treatment of carbon black {; Purification} - C01P 2004/50: Agglomerated particles - C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS} - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS ## Abstract A method for making a pigment dispersion can include dispersing pigment particles in an aqueous liquid medium to form a dispersion, adding a first monomer to form a dispersive coating on the pigment particles, adding a second monomer to the dispersion, and forming a polymer coating on the surface of the pigment particles by polymerizing the second monomer with the first monomer, wherein the polymer coating includes at least one urethane linkage or urea linkage. ## Claims ### Claim 1 A method for making an encapsulated pigment dispersion, comprising: dispersing pigment particles in an aqueous liquid medium to form a dispersion; adding a first monomer to the dispersion, wherein the first monomer forms a dispersive coating on the pigment particles; adding a second monomer to the dispersion after formation of the dispersive coating, the adding of the second monomer to the dispersion beginning polymerization in the dispersion of the second monomer with the first monomer; and forming a polymer coating on the surface of the pigment particles by polymerizing the second monomer with the first monomer in the dispersive coating, thereby creating encapsulated pigment particles; wherein the polymer coating includes at least one urethane linkage or urea linkage. ### Claim 2 (depends on 1) The method of claim 1, wherein the polymer coating includes the urethane linkage and not the urea linkage. ### Claim 3 (depends on 1) The method of claim 1, wherein the polymer coating includes the urea linkage and not the urethane linkage. ### Claim 4 (depends on 1) The method of claim 1, wherein the polymer coating includes the urethane linkage and the urea linkage. ### Claim 5 (depends on 1) The method of claim 1, wherein the first monomer is a hydrophobic polyol. ### Claim 6 (depends on 5) The method of claim 5, wherein the second monomer is a polyisocyanate, resulting in the urethane linkage. ### Claim 7 (depends on 5) The method of claim 5, wherein the hydrophobic polyol is a diol. ### Claim 8 (depends on 5) The method of claim 5, wherein the hydrophobic polyol includes at least one acid group. ### Claim 9 (depends on 5) The method of claim 5, wherein the second monomer is a diisocyanate. ### Claim 10 (depends on 1) The method of claim 1, wherein the first monomer is a polyisocyanate. ### Claim 11 (depends on 10) The method of claim 10, wherein the second monomer is a polyol, resulting in the urethane linkage. ### Claim 12 (depends on 10) The method of claim 10, wherein the hydrophobic polyol includes at least one acid group. ### Claim 13 (depends on 10) The method of claim 10, wherein the second monomer is a polyamine, resulting in the urea linkage. ### Claim 14 (depends on 1) The method of claim 1, wherein the first monomer is sufficient to disperse the pigment particles in the aqueous liquid medium with no surfactants present in the aqueous liquid medium. ### Claim 15 (depends on 1) The method of claim 1, wherein the pigment particles, first monomer, and second monomer are present in the aqueous liquid medium at a weight percentage ratio in which about 1.0 part pigment is included with about 0.1 to about 5.0 parts first monomer, and from 0.1 to about 5.0 parts second monomer. ### Claim 16 (depends on 15) The method of claim 15, wherein the pigment particles, first monomer, and second monomer are present in the aqueous liquid medium at weight percentage ratio of about 1.0:0.5:5.0. ### Claim 17 A precursor to an encapsulated pigment dispersion, comprising: an aqueous liquid medium; pigment particles dispersed in the aqueous liquid medium, wherein the pigment particles are coated with a first monomer and are dispersed by the first monomer; and a second monomer added to the aqueous liquid medium and to be polymerized with the first monomer previously coated on the pigment particles to produce a polymer coating encapsulating the pigment particles and including at least one urethane linkage; wherein the pigment particles, the first monomer and the second monomer are present in a weight percentage ratio of 1.0:1.5:0.5. ### Claim 18 (depends on 17) The precursor to the pigment dispersion of claim 17, wherein the precursor is substantially free of surfactant. ### Claim 19 (depends on 17) The precursor to the pigment dispersion of claim 17, wherein the first monomer is a hydrophobic polyol, and the second monomer is a polyisocyanate. ### Claim 20 (depends on 17) An ink-jet ink comprising the pigment dispersion formed from the precursor of claim 17.