Colored pigment powders in a compartmented container
A resin-free pigment concentrate carries a high pigment content; if the dispersant does not anchor firmly enough, the pigment re-agglomerates under high shear, the viscosity of the paste soars with it, and the resistance in milling and let-down rises, so the tinting strength and the storage of the color paste both suffer.
Chemi Tech supplies dispersants for printing ink coloring systems and resin-free pigment concentrates, drawn from the dispersant KMK-130 series; the dosage varies with the pigment grade, the surface treatment and the target pigment content. KMK-130 grips the pigment surface through its anchoring groups, does not desorb under high-shear milling, and brings a solid drop in viscosity; the KMK-133 of the same series is a closer fit for printing ink systems and is a common grade for the resin-free pigment concentrate class. Chemi Tech sets the dispersion performance against the pigment grade and the target pigment content, and selects the fitted dispersant for the customer.
Advantages of Chemi Tech Dispersants
Chemi Tech dispersant KMK-130 series is built around resin-free concentrates, its anchoring groups do not desorb under high shear, and the pigment stays stably dispersed; moreover, it lowers viscosity and lifts the pigment loading capacity, so the paste viscosity stays controllable; in addition, it adapts widely to carbon black and organic pigments, and the color paste does not re-agglomerate or float on storage; and wetting in the resin-free system is thorough, so the tinting strength and the color development hold steady.
Industry Pain Points and Solutions
The re-agglomeration of a resin-free pigment concentrate is mostly not a matter of insufficient milling but of the dispersant losing its anchor at high pigment content; the consequence is a soaring viscosity and a coarse color paste.
The foremost worry is that the rise in pigment content is blocked. As the pigment content goes up the system viscosity rises, and the resistance in milling and let-down grows with it. Chemi Tech's answer is to dose the markedly viscosity-lowering KMK-130 at the feed end of the milling stage, so the pigment is anchored the moment it is wetted.
The hardest part is re-agglomeration after milling. When the dispersant anchors too weakly, the pigment closes in again after high shear and the color paste turns coarse. KMK-133 from Chemi Tech anchors steadily, and the resin-free concentrate does not re-agglomerate after milling.
There is also the floating on storage. After the color paste has stood for a while it floats and mottles, and the coloring stability falls. Chemi Tech sets the anchoring performance against the pigment grade, calibrates the dosage of the KMK-130 series together with the milling time, and the color paste holds steady on storage.
Typical Operating Conditions and Verification
Customer: a printing ink manufacturer in Zhejiang, for the milling and let-down of resin-free pigment concentrates.
At this plant the viscosity of the pigment concentrate soared once the pigment content was raised, the color paste turned coarse and floated, and the coloring stability stayed limited for a long time. The solution Chemi Tech dispersant gave for the situation was: taking the pigment grade and the target pigment content into account, choose the KMK-130 series, set the dosing point at the feed end of the milling stage, and grade the dosage by pigment content. After it was put into use, the paste viscosity came back to a controllable range, the color paste neither re-agglomerated nor floated, and the tinting strength held steady.
Frequently Asked Questions
Once a dispersant is added to a resin-free concentrate, will it leave residues that affect the coloring?
That concern has some basis, since a few grades leave components behind in the paste while dispersing the pigment. KMK-130 has been through dispersion and coloring comparisons for different pigment grades at Chemi Tech, and only the dosage that colors steadily is recommended. The dosage is set by the pigment grade and the solid content, and Chemi Tech gives its fitted range after milling and coloring comparisons.