Compositions and methods comprising pigments and polyprotic dispersing agents
View Patent ↗In various embodiments, a pigment composition is provided comprising a base particle and a dispersing agent, the dispersing agent comprising a salt and/or ester of: (i) an amine, alcohol, and/or alkanol amine and (ii) a polyprotic acid, wherein the mole ratio of the amine, alcohol, and/or alkanol amine to the polyprotic acid is greater than 3:1. In various embodiments, the pigments have improved stability, hiding power, tint strength, and/or gloss.
1. A method of making titanium dioxide pigment comprising adding a polyprotic acid to an amine, alcohol, and/or alkanol amine; wherein the mole ratio of amine, alcohol, and/or alkanol amine to polyprotic acid is greater than 3:1, to form a dispersing agent having a mole ratio of amine, alcohol, and/or alkanol amine to polyprotic acid of greater than 3:1; and adding titanium dioxide to the dispersing agent to make the titanium dioxide pigment, wherein the titanium dioxide has a particle size range of between about 0.1 and about 1 micron.
2. A method of making titanium dioxide pigment according to claim 1 , wherein the pigment has improved stability, gloss, hiding power, tint strength or a combination thereof.
3. A method of making titanium dioxide pigment according to claim 1 , wherein the polyprotic acid comprises phosphoric acid, polyphosphoric acid, phosphonic acid, metaphosphoric acid, phosphinic acid, pyrophosphoric acid, hypophosphoric acid, phosphorous pentaoxide, other phosphorus acid derivatives, or any other phosphorous containing acids or combinations thereof and the amine or alcohol or alkanol amine comprises at least one amino alcohol, diol, aminopolyol, polyol, primary amine, secondary amine, tertiary amine or combination thereof.
4. A method of making titanium dioxide pigment according to claim 3 , wherein the amine, alcohol, and/or alkanol amine comprises triethanolamine, 2-amino-2-methyl-1 propanol, 1-amino-1-butanol, 1-amino-2-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-hydroxymethyl1-1,3-propanediol, methanol, isopropyl alcohol, butanol, methoxypropanol, trimethylolethane, trimethylolpropane, pentaerythritol, ethylene glycol, propylene glycol, or combination thereof.
5. A method of making titanium dioxide pigment according to claim 1 , wherein the dispersing agent comprises from about 0.01 percent to about 5 percent by weight based on the weight of titanium dioxide.
6. A method of making titanium dioxide pigment according to claim 1 , wherein the titanium dioxide is treated with silica, zirconia, alumina, or combination thereof.
7. A method of making titanium dioxide pigment according to claim 1 , wherein the mole ratio of the amine, alcohol and/or alkanol amine to the polyprotic acid is from 4:1 to about 20:1.
8. A method of making titanium dioxide pigment comprising adding a polyprotic acid to an amine, alcohol, and/or alkanol amine; wherein the polyprotic acid contains substantially no carboxylic acid, and wherein the mole ratio of amine, alcohol, and/or alkanol amine to polyprotic acid is greater than 3:1, to form a dispersing agent having a mole ratio of amine, alcohol, and/or alkanol amine to polyprotic acid of greater than 3:1; and adding titanium dioxide to the dispersing agent to make the titanium dioxide pigment.
9. A method of making titanium dioxide pigment according to claim 8 , wherein the polyprotic acid comprises phosphoric acid, polyphosphoric acid, phosphonic acid, metaphosphoric acid, phosphinic acid, pyrophosphoric acid, hypophosphoric acid, phosphorous pentaoxide, other phosphorus acid derivatives, or any other phosphorous containing acids or combinations thereof and the amine or alcohol or alkanol amine comprises at least one amino alcohol, diol, aminopolyol, polyol, primary amine, secondary amine, tertiary amine or combination thereof.
10. A method of making titanium dioxide pigment according to claim 9 , wherein the amine, alcohol, and/or alkanol amine comprises triethanolamine, 2-amino-2-methyl-1 propanol, 1-amino-1-butanol, 1-amino-2-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-hydroxymethyl1-1,3-propanediol, methanol, isopropyl alcohol, butanol, methoxypropanol, trimethylolethane, trimethylolpropane, pentaerythritol, ethylene glycol, propylene glycol, or combination thereof.
11. A method of making titanium dioxide pigment according to claim 8 , wherein the dispersing agent comprises from about 0.01 percent to about 5 percent by weight based on the weight of titanium dioxide.
12. A method of making titanium dioxide pigment according to claim 8 , wherein the titanium dioxide is treated with silica, zirconia, alumina, or combination thereof.
13. A method of making titanium dioxide pigment according to claim 8 , wherein the mole ratio of the amine, alcohol and/or alkanol amine to the polyprotic acid is from 4:1 to about 20:1.
14. A method of making titanium dioxide pigment comprising: a) preparing an aqueous slurry of titanium dioxide; b) adding in any order: (i) a polyprotic acid that contains substantially no carboxylic acid to the slurry, ii) an amine, alcohol, and/or alkanol amine to the slurry, wherein the mole ratio of amine, alcohol, and/or alkanol amine to the polyprotic acid is greater than 3:1.
15. A method of making titanium dioxide pigment according to claim 14 , wherein the polyprotic acid is added to the slurry before wet treatment and the amine, alcohol, and/or alkanol amine is added during micronization of the pigment.
16. A method of making titanium dioxide pigment according to claim 14 , wherein the polyprotic acid and the amine, alcohol, and/or alkanol amine is added to the titanium dioxide prior to wet treating, filtering, drying or micronizing the titanium dioxide.
17. A method of making titanium dioxide pigment according to claim 14 , wherein the polyprotic acid and the amine, alcohol, and/or alkanol amine are added to the titanium dioxide pigment as a mixture.
18. A method of making titanium dioxide pigment according to claim 14 , wherein the polyprotic acid and the amine, alcohol, and/or alkanol amine are added to the titanium dioxide pigment separately.
19. A method of making titanium dioxide pigment comprising: a) preparing an aqueous slurry of titanium dioxide; b) adding a polyprotic acid to the slurry, and c) adding an amine, alcohol, and/or alkanol amine during micronization of the pigment, wherein the mole ratio of amine, alcohol, and/or alkanol amine to the polyprotic acid is greater than 3:1.
20. A method of making titanium dioxide pigment comprising: a) preparing an aqueous slurry of titanium dioxide; b) adding an amine, alcohol, and/or alkanol amine a polyprotic acid to the slurry before wet treatment, and c) adding a polyprotic acid during micronization of the pigment, wherein the polyprotic acid contains substantially no carboxylic acid, and wherein the mole ratio of amine, alcohol, and/or alkanol amine to the polyprotic acid is greater than 3:1.