1. Introduction

Coating additives, though typically accounting for only 0.1%–5% of a formulation, play a decisive role in pigment dispersion, foam control, surface leveling, and long-term stability of coatings, inks, and pigment pastes. Among these additives, dispersants and defoamers are the most technically demanding and widely used categories. Dispersants facilitate the deagglomeration of pigment aggregates and maintain colloidal stability through anchoring group adsorption and steric/electrostatic repulsion, while defoamers suppress and eliminate foam generated during high-speed dispersion and application processes.

Dongguan DENSON Functional Materials Co., Ltd. (DENSON) has developed a comprehensive additive portfolio, including the F20 polyurethane-based hyperdispersant, the 0913 water/oil universal polycarboxylate dispersant, and the DS-6800 silicone defoamer. These products have been validated in solvent-based, water-based, and UV-curable systems across coatings, inks, and pigment paste manufacturing. This article provides a technical overview of additive mechanisms, application cases, and selection parameters for industrial practitioners.

Figure 1. Industrial chemical additive products, including dispersants, defoamers, and wetting agents for coating and ink applications

2. Technical Features and Mechanism

2.1 Dispersant Mechanism: Anchoring Group and Solvated Chain

A dispersant is a surface-active substance that reduces the interfacial tension between pigment particles and the dispersion medium, promotes deagglomeration, and prevents re-agglomeration. Modern dispersant theory is based on the dual-function model of "anchoring group + solvated chain": the anchoring group adsorbs onto the pigment surface through ionic bonds, hydrogen bonds, or van der Waals forces, while the solvated chain extends into the medium to provide steric hindrance and electrostatic repulsion.

Research published in the Journal of Applied Polymer Science (2025, DOI: 10.1002/app.56144) demonstrated that PEGylated partially hydrolyzed poly(N-vinyl amide) as a carbon black dispersant achieves a zeta potential of -42 mV and reduces average particle size from 320 nm to 95 nm, through hydrogen bonding of amide groups to oxygen-containing functional groups on carbon black surfaces and steric stabilization provided by PEG chains.

RSC Advances (2025, 15, 44517–44525, DOI: 10.1039/d5ra07498c) reported a synergistic dispersion system using SDBS and polyacrylate terpolymer for multi-layer graphene in water. The benzene ring of SDBS anchors to graphene through π-π stacking, while the polyacrylate chain provides electrostatic repulsion, achieving a dispersion concentration of 8 mg/mL with no significant sedimentation after 30 days.

2.2 Hyperdispersant Molecular Design

ACS Applied Polymer Materials (2026, 8(6), 4573–4586, DOI: 10.1021/acsapm.6c00349) proposed an innovative soft-core/hard-shell gradient copolymer for pigment encapsulation. The hydrophobic polyester core anchors to organic pigment surfaces, while the hydrophilic polyacrylic acid shell provides water dispersion stability. Phthalocyanine blue pastes prepared with this dispersant achieved 45% pigment content, fineness ≤5 μm, and viscosity change<8% 30="" 50="" after="" days="" at="">

2.3 Defoamer Mechanism

A defoamer is a substance that suppresses foam generation or breaks existing foam. Silicone defoamers operate through three processes: (1) spreading on the foam liquid film surface, displacing foam-stabilizing surfactants; (2) entering the film and causing local thinning due to surface tension differences; (3) film rupture when thickness falls below the critical value.

The DENSON DS-6800 silicone defoamer uses a composite system of polydimethylsiloxane and hydrophobic silica. The siloxane chain provides low surface tension (~20 mN/m), while silica particles act as foam-breaking cores that puncture the liquid film. At 0.1%–0.3% dosage in water-based coatings, it effectively eliminates bubbles generated during grinding and letdown, without affecting intercoat adhesion or recoatability.

Figure 2. Pigment grinding and dispersion process in resin binder, where dispersant anchoring and solvation stabilize pigment particles

3. Application Case 1: F20 in High-Pigment Carbon Black Paste

High-color carbon black (C.I. Pigment Black 7) has a large specific surface area (200–300 m²/g) and high surface energy, making it extremely prone to flocculation in solvent-based systems. The DENSON F20 polyurethane hyperdispersant, with ureido anchoring groups that form strong hydrogen bonds with oxygen-containing functional groups on carbon black surfaces and polyester solvated chains that fully extend in ester/aromatic solvents, addresses this challenge effectively.

In a carbon black paste formulation (carbon black 20%, F20 8%, acrylic resin 30%, solvent 42%), the F20-dispersed paste achieves fineness ≤7.5 μm (GB/T 1724-2019 Hegman gauge), with grinding time reduced by approximately 30% compared to conventional dispersants. After 30 days at 50°C, viscosity change is<10% with="" no="" significant="" coarsening="" or="" sedimentation.="">

4. Application Case 2: 0913 in Water-Based Phthalocyanine Blue Paste

The DENSON 0913 water/oil universal dispersant features a polycarboxylate structure where carboxylate groups ionize in water to provide electrostatic repulsion, while hydrophobic segments provide additional steric hindrance. This product works in both water-based and polar solvent-based systems.

In a water-based phthalocyanine blue paste (pigment 35%, 0913 6%, deionized water 59%), 0913 reduces average pigment particle size from 180 nm to 85 nm with a zeta potential of -38 mV. The paste shows excellent compatibility with various water-based acrylic emulsions and polyurethane dispersions, with no floating or flooding after tinting.

5. Application Case 3: DS-6800 in Water-Based Industrial Coatings

Water-based industrial coatings generate significant foam during high-speed dispersion and spray application, leading to pinholes and craters in the cured film. The DENSON DS-6800 silicone defoamer demonstrates excellent defoaming performance in both water-based epoxy primers and polyurethane topcoats.

In a water-based epoxy primer with 0.2% DS-6800, foam volume after high-speed dispersion (1500 rpm, 30 min) is<5 ml="">

Figure 3. Industrial coating automatic spray line, where proper defoamer use ensures defect-free film appearance and performance

6. Key Selection Parameters and Usage Recommendations

6.1 Process Optimization Guidelines

Optimal additive performance requires proper processing: (1) Dissolve dispersant in solvent/water first (500 rpm, 5 min), then add pigment in 2–3 portions with pre-dispersion (1000 rpm, 5 min each), followed by bead milling; (2) Add defoamer after grinding or during letdown (300–500 rpm, 5–10 min), avoiding high-shear addition; (3) Control bead mill discharge temperature ≤45°C to prevent dispersant desorption; (4) Use 0.6–0.8 mm yttrium-stabilized zirconia beads at 80%–85% filling and 10–12 m/s linear speed for optimal grinding efficiency.

7. Conclusion

The anchoring-solvation dual-function mechanism of dispersants and the low-surface-tension foam-breaking mechanism of defoamers form the theoretical basis for additive performance. DENSON F20, 0913, and DS-6800, through rational molecular structure design, deliver excellent performance in pigment dispersion and foam control across solvent-based, water-based, and UV-curable systems, effectively improving production efficiency and final product quality for coatings, inks, and pigment paste manufacturers.

8. FAQ

Q1: Is more dispersant always better?

No. Dispersants work best when forming a monolayer adsorption on pigment surfaces. Excess dispersant forms micelles in the liquid phase, reducing dispersion efficiency and potentially affecting film water resistance. Determine optimal dosage through gradient testing, typically 8%–30% on pigment weight.

Q2: Will silicone defoamers cause film craters?

Excessive dosage or poor compatibility can cause craters. DS-6800 is specially emulsified and does not cause craters at the recommended dosage (0.1%–0.5%). Always conduct small-sample compatibility testing before full-scale use.

Q3: Can water-based and solvent-based dispersants be interchanged?

Most dispersants are system-specific. DENSON 0913 is water/oil universal and works in both water-based and polar solvent systems. F20 is designed for solvent-based and UV systems and is not recommended for direct use in water-based formulations.

Q4: How do I evaluate dispersant-resin compatibility?

The rub-out test is the simplest method: mix the pigment paste with resin binder, apply to a glass panel, and rub a small area with a finger before surface dry. If color difference between rubbed and unrubbed areas is ΔE ≤1.0, compatibility is good; if significant color change occurs, compatibility issues exist and dispersant replacement or dosage adjustment is needed.

Q5: What is the recommended addition order for dispersants and defoamers?

Add dispersant during the grinding stage (together with pigment and solvent). Add defoamer during the letdown stage after grinding. If defoamer is added too early during high-shear grinding, the emulsification structure may be destroyed, reducing defoaming efficiency. For highly foaming systems, add 60% of defoamer at the end of grinding and 40% during letdown.

For more product information, visit Dongguan DENSON Functional Materials Co., Ltd. or refer to the Application Literature section.