Pigment cans in various colours stacked in neat rows
Organic pigments are not hard to grind, they are hard to keep. Leave pigment paste in the can for a few days and a layer of colour floats up, and stirring cannot save it: the tinted coating misses the colour tolerance, the customer returns the order, and the batch sits in the warehouse.
Chemi Tech makes dispersants for waterborne pigment pastes, coating tinting and ink colouring systems, drawn from the dispersant KMK-130 series. How a grade is matched depends on the type of pigment, the resin system and the target pigment loading. KMK-130 is a polymeric dispersant that holds the pigment surface through its anchoring groups, does not desorb under high shear grinding, covers carbon black and organic pigments broadly, and brings a substantial viscosity reduction.
Advantages of Chemi Tech Dispersants
Chemi Tech dispersant KMK-130 series holds the pigment surface through its anchoring groups and does not desorb under high shear grinding, so a finished paste sits for a month without flooding or coarsening back. The viscosity reduction is substantial as well: at the same pigment loading the paste still flows and the bead mill current holds steady. Its coverage of carbon black and organic pigments is broad, so changing pigment does not mean tearing the formulation down and starting again. Storage stability comes with it: colour is consistent top to bottom in the can, with no flooding on opening and no sediment at the bottom. The dosage runs at a small percentage of pigment weight, so the overall cost stays controllable.
A note from Chemi Tech: the behaviour above comes from a typical waterborne pigment paste grinding condition. Change the pigment type or the resin system and the results move. Run a small trial before scaling up.
Industry Pain Points and Solutions
With flooding and floating in pigment paste, what worries people most is colour difference claims coming back one after another; the root is not in the stirring, it is in whether the dispersant and the pigment hold on to each other.
The first thing to go wrong is organic pigments being hard to disperse. Organic pigments are harder to hold than inorganic ones, and if the dispersant is the wrong choice the fineness lands on target and then agglomerates back after a few days in storage. Chemi Tech runs a round of anchoring validation on each pigment in use, and the formulation follows the pigment.
What follows is changing pigment without changing formulation. When the pigment for the same colour family is switched to another brand, the surface treatment is different and a dispersant that used to hold no longer does. Chemi Tech's approach is a brand-by-brand anchoring comparison, running several dispersants side by side and using whichever holds.
One more point is colour difference claims coming back. The paste floods after a few days, the tinted coating misses the colour tolerance, and the customer returns the order. Chemi Tech's approach is to put storage stability on the validation list: test the hue again after a month in the can, and count it as passed only when both items are through.
From the anchoring comparison to the storage stability, the research department at Chemi Tech will recommend against your actual formulation.
Typical Conditions and Verification
Customer: a coatings enterprise in Guangdong, applying it to the grinding and storage stages of tinting paste.
The organic pigment paste from this plant was fine on the day it was ground, then flooded and floated after a few days, and the tinted coating missed the colour tolerance, with a good many returns. The solution offered by Chemi Tech dispersant was: against the pigment brand and the resin system, a suitable grade was selected from the KMK-130 series, a blank comparison was run first to confirm the problem sat at the anchoring layer, and then a pilot run was made on the bead mill. After the change the paste held its hue for a month and the tinting colour difference came back inside the normal range. The colour difference claims at quality control fell from several a week to the occasional one.
Frequently Asked Questions
If the pigment brand changes, does the dispersant have to change with it?
Not necessarily, but it must be validated: once the pigment surface treatment changes, a dispersant that used to hold may stop holding, and both hue and storage stability are affected. The KMK-130 Chemi Tech supplies to paste plants has been put through a pigment-by-pigment anchoring comparison, and which one to use is settled after we have seen the data. Give the pigment brand and the resin system to the technical department at Chemi Tech, and we will run the comparison and the conclusion for you.