Method of preparing a pigment press cake and uses thereof
View Patent ↗A process for preparing a pigment press cake is provided in which a pigment, a grinding agent, a polyetheramine, and a vehicle are subjected to grinding, followed by removal of the grinding agent and the vehicle to form a press cake. Also disclosed are a process to disperse the press cake with a polymeric dispersant in an aqueous vehicle to form a pigment dispersion and using the dispersion to form an aqueous ink jet ink.
1. A process for making a pigment press cake comprising the steps of:
(a) grinding a mixture comprising a pigment, a grinding agent and a vehicle to form a premix, wherein said grinding agent is insoluble in said vehicle and soluble in water,
(b) adding to said premix a polyetheramine having the formula (I):
(c) grinding said premix and said polyetheramine together; and
(d) washing with an aqueous medium to remove said grinding agent to form a press cake;
wherein each Q 1 and Q 3 is independently —OCH 2 CH 2 — or —OCH 2 CH(CH 3 )—; each Q 2 is —OCH 2 CH(CH 3 )—; R 1 is CH 2 CH(NH 2 )(CH 3 ) or NH 2 ; each R 2 and R 3 is independently C 1 -C 4 alkyl or a straight bond; each R 4 is H, C 1 -C 4 alkyl or -(Q 3 ) q -NH 2 ; each R 5 is C 1 -C 4 alkyl or a straight bond; n is an integer from 0 to 60; m is an integer from 2 to 30; p is 0; each q is an integer from 0 to 30; and said grinding agent is an inorganic salt.
2. The process of claim 1 , wherein Q 1 is —OCH 2 CH 2 —.
3. The process of claim 1 , wherein n is 0.
4. The process of claim 3 , wherein m is from 2 to 10.
5. The process of claim 1 , wherein R 1 is —CH 2 CH(NH 2 )(CH 3 ).
6. The process of claim 5 , wherein Q 1 is —OCH 2 CH 2 —.
7. A process for making an aqueous pigment dispersion comprising the steps of:
(a) grinding a mixture comprising a pigment, a grinding agent and a vehicle to form a premix, wherein said grinding agent is insoluble in said vehicle and soluble in water,
(b) adding to said premix a polyetheramine having the formula (I):
(c) grinding said premix and said polyetheramine together;
(d) washing with an aqueous medium to remove said grinding agent to form a press cake; and
(e) adding an aqueous vehicle and a polymeric dispersant, and dispersing said press cake from step (d), in this order or any other workable orders, to form a dispersion;
wherein each Q 1 , Q 2 and Q 3 is independently —OCH 2 CH 2 — or —OCH 2 CH(CH 3 )—; R 1 is C 1 -C 4 alkyl, —CH 2 CH(NH 2 )(CH 3 ) or NH 2 ; each R 2 and R 3 is independently C 1 -C 4 alkyl or a straight bond; each R 4 is H, C 1 -C 4 alkyl or -(Q 3 ) q -NH 2 ; each R 5 is C 1 -C 4 alkyl or a straight bond; n is an integer from 0 to 60; m is an integer from 2 to 30; p is an integer from 0 to 5; each q is an integer from 0 to 30; and said polymeric dispersant contains a cross-linkable moiety.
8. The process of claim 7 , further comprising an ultrafiltration step after step (e).
9. The process of claim 7 , further comprising a step of reacting said polyetheramine and said cross-linkable moiety with a cross-linking agent.
10. The process of claim 9 , wherein said cross-linking agent is one or more members selected from the group consisting of epoxide, isocyanate, carbodiimide, N-methylol, oxazoline, silane, and mixtures thereof.
11. An ink-jet ink comprising an aqueous ink-jet vehicle and an aqueous pigment dispersion, wherein said aqueous pigment dispersion is prepared by a process comprising the steps of:
(a) grinding a mixture comprising a pigment, a grinding agent and a vehicle to form a premix, wherein said grinding agent is insoluble in said vehicle and soluble in water,
(b) adding to said premix a polyetheramine having the formula (I):
(c) grinding said premix and said polyetheramine together;
(d) washing with an aqueous medium to remove said grinding agent to form a press cake; and
(e) adding an aqueous vehicle and a polymeric dispersant, and dispersing said press cake from step (d), in this order or any other workable orders, to form a dispersion;
wherein each Q 1 , Q 2 and Q 3 is independently —OCH 2 CH 2 — or —OCH 2 CH(CH 3 )—; R 1 is C 1 -C 4 alkyl, —CH 2 CH(NH 2 )(CH 3 ) or NH 2 ; each R 2 and R 3 is independently C 1 -C 4 alkyl or a straight bond; each R 4 is H, C 1 -C 4 alkyl or -(Q 3 ) q -NH 2 ; each R 5 is C 1 -C 4 alkyl or a straight bond; n is an integer from 0 to 60; m is an integer from 2 to 30; p is an integer from 0 to 5; each q is an integer from 0 to 30; and said polymeric dispersant contains a cross-linkable moiety.