PIGMENT COMPOSITIONS HAVING A REDUCED CONTENT OF ARYL AMINES OR N-ARYLACETOACETAMIDES AND OXIDATION METHODS FOR PRODUCING THE SAME
N-arylacetoacetarylide pigment compositions comprise a diazonium coupling product of a first aryl amine and an N-arylacetoacetamide formed from a second aryl amine. N-arylacetoacearylide pigment compositions may be contacted with an oxidant in an aqueous phase to decrease the amount(s) of second aryl amine and/or N-arylacetoacetamide that are present in the N-arylacetoacetarylide pigment composition. The N-arylacetoacetarylide pigment compositions may be present in a pigment dispersion, which may be stably maintained following oxidation.
1 . A method comprising:
providing an N-arylacetoacetarylide pigment composition comprising a diazonium coupling product of a first aryl amine and an N-arylacetoacetamide formed from a second aryl amine;
wherein the N-arylacetoacetarylide pigment composition comprises at least some residual N-arylacetoacetamide that has not undergone diazonium coupling and/or at least some residual second aryl amine that has not reacted to form the N-arylacetoacetamide and/or has hydrolyzed from the N-arylacetoacetamide; and
contacting the N-arylacetoacetarylide pigment composition with an oxidant in an aqueous phase at a temperature and for a time sufficient to decrease a concentration of the residual N-arylacetoacetamide and/or the residual second aryl amine in the N-arylacetoacetarylide pigment composition.
2 . The method of claim 1 , wherein the aqueous phase has an alkaline pH.
3 . The method of claim 2 , wherein the alkaline pH is maintained by a hydroxide compound, a carbonate salt, a bicarbonate salt, or any combination thereof.
4 . The method of claim 2 , wherein the oxidant comprises a persulfate salt, a hypochlorite salt, or any combination thereof.
5 . The method of claim 2 , wherein the temperature is about 50° C. to about 95° C. and the time is about 1 hour to about 4 hours.
6 . The method of claim 2 , wherein the temperature is about 70° C. to about 90° C.
7 . The method of claim 2 , wherein the N-arylacetoacetarylide pigment composition comprises an N-arylacetoacetarylide selected from the group consisting of Pigment Yellow 17, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 180, and any combination thereof.
8 . The method of claim 2 , wherein the second aryl amine is o-anisidine.
9 . The method of claim 2 , wherein the temperature and time are sufficient to decrease the concentration of the N-arylacetoacetamide by at least about 80% on a mass basis relative to the N-arylacetoacetarylide pigment composition.
10 . A method comprising:
providing a pigment dispersion comprising an N-arylacetoacetarylide pigment composition dispersed in an aqueous phase in the presence of a polymeric dispersant and/or at least one surfactant, the N-arylacetoacetarylide pigment composition comprising a diazonium coupling product of a first aryl amine and an N-arylacetoacetamide formed from a second aryl amine;
wherein the N-arylacetoacetarylide pigment composition comprises at least some residual N-arylacetoacetamide that has not undergone diazonium coupling and/or at least some residual second aryl amine that has not reacted to form the N-arylacetoacetamide and/or has hydrolyzed from the N-arylacetoacetamide;
contacting the pigment dispersion with an oxidant at an alkaline pH at a temperature and for a time sufficient to decrease a concentration of the residual N-arylacetoacetamide and/or the residual second aryl amine in the N-arylacetoacetarylide pigment composition;
wherein the dispersion remains stable after being contacted with the oxidant.
11 . The method of claim 10 , wherein the oxidant comprises a persulfate salt.
12 . The method of claim 11 , wherein the persulfate salt comprises ammonium persulfate, sodium persulfate, or any combination thereof.
13 . The method of claim 10 , wherein the alkaline pH is about 7.1 to about 14.
14 . The method of claim 10 , wherein the alkaline pH is maintained by a hydroxide compound, a carbonate salt, a bicarbonate salt, or any combination thereof.
15 . The method of claim 10 , wherein the temperature is about 50° C. to about 95° C. and/or the time is about 1 hour to about 4 hours.
16 . The method of claim 10 , wherein the temperature is about 70° C. to about 90° C.
17 . The method of claim 10 , wherein the N-arylacetoacetarylide pigment composition comprises an N-arylacetoacetarylide selected from the group consisting of Pigment Yellow 17, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 180, and any combination thereof.
18 . The method of claim 10 , wherein the second aryl amine is o-anisidine.
19 . The method of claim 10 , wherein the temperature and time are sufficient to decrease the concentration of the N-arylacetoacetamide by at least about 80% on a mass basis relative to the N-arylacetoacetarylide pigment composition in the pigment dispersion.
20 . A pigment dispersion comprising:
an N-arylacetoacetarylide pigment composition dispersed in an aqueous phase in the presence of a polymeric dispersant and/or at least one surfactant, the N-arylacetoacetarylide pigment composition comprising a diazonium coupling product of a first aryl amine and an N-arylacetoacetamide formed from a second aryl amine;
wherein a concentration of residual N-arylacetoacetamide in the pigment dispersion is about 4000 μg/g pigment or below.