|
|
| |
|
|
| |
|
Frank Lee
Graphic Arts Chemist |
| |
|
|
| |
 |
How can I achieve good working viscosities at high pigment loadings in aqueous dispersions using lithol rubine or other troublesome pigments? |
| |
|
Many commercial pigments contain residue and contaminants resulting from their manufacture. For example, when a metallized AZO red such as lithol rubine is being produced, anionic groups are ionized in an aqueous solution and reacted with calcium to form an insoluble metallized pigment. This slurry is then washed to remove the unreacted Ca2+ ions and processed further into a presscake or dry powder form. While grinding the pigment to make a dispersion, any remaining unreacted Ca2+ ions may cause bridging between anionic sites found on the pigment and grind resin, leading to flocculation and excessive viscosities. Surfynol® CT-171 grind aid helps complex these ions by offering rapid wetting and stabilization of the pigment particles, resulting in a fluid aqueous dispersion. Lower dispersion viscosities allow the formulator to attain higher pigment loadings and optimal color development, even at elevated processing temperatures. |
|
 |
|
|
