Industrial piping criss-crossing a plant area
Epoxy primer is ground until the fineness passes, yet on standing the particles gather again, and spraying leaves sheets of grain and pinholes on the film, so the hiding power and the anticorrosion performance of the primer suffer together.
Chemi Tech supplies dispersants for epoxy primer, industrial anticorrosion coatings and coil coatings, drawn from the dispersant KMK-410 series; the dosage varies with the pigment grade, the surface treatment method and the target solids content. KMK-410 grips the pigment surface through anchoring groups and does not desorb under high-shear grinding, lowering viscosity and raising pigment loading; the KMK-412 in the same series is a wetting dispersant, better suited to solvent-borne systems or cases with higher demands on transparency and hiding power. Chemi Tech compares dispersion performance against the pigment parameters, and matches the customer with the dispersant that fits.
Advantages of Chemi Tech Dispersants
Chemi Tech dispersant KMK-410 series grips the pigment surface through anchoring groups and does not desorb under high-shear grinding, so re-agglomeration on standing after grinding is unlikely; at the same time it lowers viscosity and raises pigment loading, so the carrying capacity for inorganic pigments such as titanium dioxide rises accordingly; on top of that, its adaptability to inorganic and organic pigments is broad, storage is stable, with no re-agglomeration and no flooding, and the hiding power of the film stays stable.
Industry Pain Points and Solutions
Re-agglomeration in epoxy primer is mostly not a matter of insufficient grinding capacity, but of the dispersant's anchoring to the pigment surface failing in later process steps; the consequence is grain in the film and a drop in hiding power.
The first problem to surface is re-agglomeration after grinding. Just after grinding the particle size distribution has narrowed, but after standing for a while the particles come close again and the particle size climbs back. Chemi Tech's answer is to add KMK-410, whose anchoring action is stable, at the feed end of the grinding stage, so that the agent has already attached the moment the pigment is wetted.
Next comes the rise in pigment loading. As the carrying capacity for inorganic pigments such as titanium dioxide rises, the viscosity of the system goes up and the resistance to grinding and transfer grows. Chemi Tech runs a dispersion comparison according to the pigment grade and the surface treatment method, and calibrates the dosage together with the grinding time.
There is one more point in the drift of the storage state. A finished coating left to stand for a while shows re-agglomeration and flooding, and by the time it is sprayed its state differs from what it was at the factory test. Chemi Tech runs a stability comparison over the storage period, so that the coating keeps a consistent state before spraying.
Typical Operating Conditions and Verification
Customer: an industrial anticorrosion coatings manufacturer in Anhui, for the grinding and let-down stages of epoxy primer.
The plant's epoxy primer showed re-agglomeration as soon as it stood after grinding, spraying carried grain and pinholes out of the film, hiding power dropped, and batch consistency was long constrained. The solution Chemi Tech dispersant gave for the situation was: taking the pigment grade and the target solids content into account, choose the KMK-410 series, set the dosing point at the feed end of the grinding stage, and grade the dosage by solids content. After the solution was in place, the particle size of the coating stayed stable on standing, grain in the film dropped noticeably, and hiding power returned to the normal range.
Frequently Asked Questions
Once the dispersant dosage is raised, will the anticorrosion performance of the epoxy primer be affected?
The concern has some basis, since a small number of categories leave components in the film while dispersing the pigment. KMK-410 has completed dispersion and anticorrosion comparisons at different dosages at Chemi Tech, and only dosages at which the film performs stably are recommended. The dosage depends on the pigment grade, and Chemi Tech gives its dosage recommendation after the grinding and spraying comparison.