1. Introduction

Polymeric dispersants are the key additive that turns dry pigments into stable, high-performance colorants. This article presents three verified application cases of polymeric dispersants: anticorrosive industrial coatings, rotogravure printing inks, and fiber-reinforced composites. Each case lists the formulation context, process, and measured performance data. For more literature, see the DENSON Literature and the DENSON website.

2. Technical Features

In these cases the polymeric dispersant acts by anchoring on pigment surfaces and providing steric stabilization. A block copolymer with acid/amine anchor and polyester/polyether tail was used. The main lever is dosage: below the optimum the millbase viscosity stays high; above it the paint performance declines. The optimum is taken at the viscosity minimum.

3. Case 1: Anticorrosive Industrial Coating

A heavy-duty epoxy anticorrosive coating for steel structures used a polymeric dispersant at 2.0% on titanium dioxide and iron oxide red. After sand milling, Hegman fineness reached 15 µm. The dry film passed 720 h salt-spray with no blistering (ASTM B117), and adhesion reached grade 1 (ASTM D3359). Compared with a low-molecular surfactant, anti-settling improved and color acceptance was more uniform.

Fig.1 Anticorrosive coating applied to steel structure

4. Case 2: Rotogravure Printing Ink

A solvent-based rotogravure ink (PVC/OPP packaging) used a polymeric dispersant at 1.8% on pigment. The millbase viscosity dropped to 18 s (4-mm cup) and fineness to 7.5 µm. Gloss reached 85 GU at 60°, and scuff resistance improved. The ink showed no floe after 7 days storage, and print density variation was within ±5%.

Fig.2 Rotogravure printing press with CMYK rollers

5. Case 3: Fiber-Reinforced Composite

A pigmented SMC/BMC composite (glass-reinforced polyester) used a polymeric dispersant to improve pigment wet-out and reduce fiber read-through. Color dispersion was uniform, gel coat appearance improved, and mechanical properties (flexural strength) stayed within specification. The dispersant also reduced filter pressure rise during compounding.

Fig.3 Automated industrial coating line

6. Key Parameters and Recommendations

Choose the dispersant anchor to match the pigment surface and the tail to the resin/solvent system; screen dosage around the viscosity minimum.

7. Conclusion

The three cases show that a properly selected polymeric dispersant simultaneously lowers millbase viscosity, improves fineness and stabilizes color, supporting coatings, inks and composite applications.

8. FAQ

Q1. How does a polymeric dispersant help anticorrosive coatings?
It stabilizes pigments so they stay uniformly dispersed, reducing settling and improving film continuity, which directly helps salt-spray and adhesion performance.

Q2. What fineness is needed for gravure ink?
Generally ≤10 µm, ideally 7.5-8 µm, to avoid doctor-blade streaks and maintain high gloss.

Q3. Can one dispersant cover both solvent and water systems?
No. Anchor chemistry must match the pigment and tail solubility must match the medium; separate grades are normally used.

Q4. Does higher dosage always give better dispersion?
No. Above the viscosity minimum excess dispersant can weaken film properties and increase cost; optimize by viscosity curve.