Integrated Additive Solution for Waterborne Epoxy Primers: One-Stop Approach to Dispersion, Wetting, Foam Control, and Leveling

Introduction: Additive Challenges in Waterborne Epoxy Primers

When formulating waterborne epoxy primers, formulators often face multiple challenges: uneven pigment dispersion leading to floating and flooding, poor wetting on low-energy surfaces causing cratering, large amounts of microfoam generated during high-speed mixing that is difficult to eliminate, and inadequate leveling that compromises anti-corrosion performance. A single additive can rarely address all these issues simultaneously; a synergistic, integrated solution is required. The following approach, based on Tianjin Hi-Perferal’s Toynol® series products, offers a systematic resolution to the four core requirements of waterborne epoxy primer formulations.

1. Pigment Dispersion: Stabilizing the System at the Source

In waterborne epoxy primers, the dispersion stability of inorganic pigments such as titanium dioxide, iron oxide red, and anti-corrosive fillers directly determines film density and anti-corrosion performance. **Toynol® DS-195H** or **Toynol® DS-195L** is recommended as the primary dispersant.

• **DS-195H** is a non-ionic polymeric dispersant that combines steric hindrance and electrostatic repulsion for a dual stabilization mechanism. It is particularly suitable for difficult-to-disperse pigments such as transparent iron oxide and titanium dioxide, effectively reducing grind-base viscosity and preventing re-agglomeration and flocculation.
• **DS-195L** focuses more on controlled-flocculation performance and cost-effectiveness, making it suitable for conventional pigment and filler systems. It is also APEO-free and environmentally friendly.

Recommended dosage: Conduct a dosage screening at 0.5%–2.0% based on pigment weight, added during the grinding stage.

2. Substrate Wetting: Addressing Craters and Adhesion Issues

Waterborne systems have high surface tension and often exhibit poor wetting on metal substrates (especially oily or smooth surfaces) and concrete. **Toynol® Superwet-320** or **Toynol® FS-204PG** is recommended.

• **Superwet-320** rapidly reduces dynamic surface tension (static surface tension as low as 26.2 dyn/cm at 0.1% aqueous solution), providing strong wetting power on low-energy surfaces and effectively preventing craters and fisheyes.
• **FS-204PG** combines wetting and foam-control functions, making it suitable for high-speed dispersion or spray application processes to suppress microfoam generated during production.

Recommended dosage: 0.3%–0.5% of the total formulation, added during the let-down stage.

3. Foam Control: Eliminating Microfoam and Surface Defects

Waterborne epoxy resins themselves, along with emulsifiers and wetting agents, readily introduce foam, leading to pinholes and volcano craters in the film. A combination of molecular defoamers and deaerators is recommended.

• Grinding stage (foam suppression): **Toynol® Foamic 024** is recommended. It is a non-ionic organic polymer defoamer, free of silicone and mineral oil, which helps reduce the risk of craters and is particularly effective against stubborn microfoam. Recommended dosage: 0.2%–0.5%.
• Let-down stage (deaeration): **Toynol® DF-80D** is recommended. It features a gemini non-ionic structure, rapidly breaking foam and providing lasting suppression, while offering excellent compatibility to help avoid film hazing or craters. Recommended dosage: 0.1%–0.3%.

4. Leveling and Appearance: Promoting Flow and Flatness

With dispersion, wetting, and foam control in place, a leveling agent further enhances film uniformity. **Toynol® FS-620** is recommended. As a gemini surfactant with an acetylenic diol polyether structure, it provides efficient wetting while also offering good foam-control capability. It promotes flow and leveling of the coating during the wet-film stage, helping reduce brush marks and roller marks.

Recommended dosage: 0.3%–0.5% of the total formulation.

Integrated Formulation Recommendations and Sample Requests

The additive combination described above (DS-195H/DS-195L + Superwet-320/FS-204PG + Foamic 024/DF-80D + FS-620) forms a complete closed-loop covering “dispersion – wetting – defoaming – leveling,” significantly enhancing the application tolerance and final film performance of waterborne epoxy primers.

For free samples or compatibility testing tailored to your specific resin system, please contact the Tianjin Hi-Perferal technical team. Please provide your formulation resin type and process requirements, and we will offer precise dosage optimization recommendations.