Carbon based black toners prepared via limited coalescence process
View Patent ↗A black toner composition is disclosed. The composition includes toner particles prepared by a chemical process of manufacture including carbon black pigment, a first addition polymer comprising carboxylic acid groups along the polymer backbone, and a thermoplastic second polymer binder distinct from the first addition polymer. In the composition, the first polymer has an Acid Value of from 30 to 220 and is present at a weight ratio of greater than 1:2 relative to the amount of carbon, and at a relatively lower weight percent than the second polymer.
1. A black toner composition comprising toner particles prepared by a chemical process of manufacture comprising carbon black pigment, a first addition polymer comprising carboxylic acid groups along the polymer backbone, and a thermoplastic second polymer binder distinct from the first addition polymer, wherein the first polymer has an Acid Value of from 50 to 200 and is present at a weight ratio of greater than 1:2 relative to the amount of carbon black pigment, and at a relatively lower weight percent than the second polymer, and wherein the first addition polymer covers and shields the carbon black pigment particles.
2. A toner composition according to claim 1 , wherein the first addition polymer has an Acid Value of from 50-150.
3. A toner composition according to claim 1 , wherein the first addition polymer is present at a weight ratio of from 1:1 to 3:1 relative to the amount of carbon black pigment.
4. A toner composition according to claim 1 , wherein the first addition polymer has a weight average molecular weight Mw of from 3,000-20,000.
5. A toner composition according to claim 1 , wherein the toner particles have a mean volume-average diameter of less than about 8 μm, and include 1 wt. % to 20 wt. % carbon pigment.
6. A toner composition according to claim 1 , wherein the toner particles have a mean volume-average diameter of from 3 μm to 7 μm, and include 3 wt. % to 10 wt. % of carbon pigment.
7. A toner composition according to claim 1 , wherein the second polymer binder comprises a polyester.
8. An electrographic developer comprising the toner of claim 1 and carrier particles.