Close-up of a powder sample in a black tray, the particle state clearly defined
The fineness of the carbon black paste has clearly been ground to spec, yet jetness sits a grade below the benchmark, and with the same batch of pigment laid side by side the tinting strength falls a breath short; in the end the customer runs a colour card against it and the regrinding all lands on that one drum.
Chemi Tech makes polymeric dispersants for water-based pigment pastes, paint tinting and ink colouring systems, from the dispersant KMK-130 series. Which grade is added depends on the pigment type, the surface treatment process and the target pigment loading. For carbon black, KMK-130 is built in this group in the direction of carbon black viscosity reduction and tinting strength; for ink systems KMK-133 is the better fit, and for the resin-free pigment concentrate grade KMK-133 is the common type. Send in the formulation backbone and the target loading of the paste, and we will run through these items first before giving you a position, which also saves you working through the grades one at a time.
Advantages of Chemi Tech Dispersants
The Chemi Tech dispersant KMK-130 series grips the pigment surface through its anchoring groups and does not desorb under high-shear grinding, and that layer is exactly where high-loading systems fail most often. The viscosity reduction is substantial, too: at the same pigment loading the paste still flows and the bead mill current holds steady. Its tolerance for carbon black and organic pigments is broad as well, so changing pigment does not mean tearing the formulation down and starting over. The finished paste is stable in storage, not thickening back or floating colour in a month, with tone consistent from top to bottom of the drum. On top of that the dosage runs at a small percentage of pigment weight, so the overall cost sits a good step below imported options.
A note from Chemi Tech: the behaviour above comes from a typical water-based carbon black paste condition. Change the pigment type or the surface treatment process and the results move. Run a small trial before scaling up.
Industry Pain Points and Solutions
The blackness and the thickness of a paste rest mostly not in the bead mill but in whether the dispersant can hold the pigment.
Changing the pigment without changing the dispersant is the first thing hit. Switch one carbon black to another supplier and the surface treatment differs, the original grade cannot hold the new pigment and jetness and tinting strength drop together, yet the blame is put on the grinding head. Chemi Tech runs one round of anchoring validation against each of the pigments you have in use, and the formulation follows the pigment.
Next comes the difficulty of having jetness and viscosity both. Reduce viscosity hard and the dispersion state of the pigment particles loosens with it and jetness will not come up. Chemi Tech's approach is to put jetness, tinting strength and viscosity into one gradient table and clear the items together.
One more point is easily missed: looking good the day it comes off the mill and thickening back after a month in storage. Fineness passes at discharge, colour floats after a month, and the problem only surfaces when it reaches the tinting centre. Chemi Tech's approach is to put heat storage stability into the verification items and to speak by shelf life.
From anchoring comparison to gradient small trials and on to the grinding parameters of a bead mill pilot run, we recommend the product against your actual requirements.
Typical Conditions and Verification
Customer: a water-based pigment paste manufacturer in Zhejiang, applying it to the grinding and blending process of carbon black paste.
The mill's carbon black paste had consistently sat one grade below the imported reference in jetness, customers gave feedback when running colour cards against it, and a fair number of batches went back for regrinding. The solution offered by Chemi Tech dispersants was: against the carbon black surface treatment process and the system resin, KMK-133 was selected from the KMK-130 series, a blank comparison was run first to confirm the problem lay in the anchoring layer, and then a bead mill pilot run followed. After the change, jetness and tinting strength each moved up a grade, the grinding current held steady, and the retained sample showed no fineness moving back after a month. When the tinting centre later ran the colour card comparison, this grade no longer needed a separate note.
Frequently Asked Questions
After switching carbon black supplier, can none of the dispersant be carried over? Not necessarily, but it has to be re-validated once. Once the pigment surface treatment changes, the anchoring groups that used to hold it may have changed hands. The KMK-133 we supply to paste mills has been compared on a per-pigment basis, and which grade to use is settled once we have looked at the data. Give the pigment grade, the surface treatment method and the target loading to our technical engineers; we produce the anchoring comparison and the gradient data and the conclusion goes to the workshop together with it.