How to Achieve Efficient Dispersion and Stability in High-Filler Intermediate Coatings?

In solvent-borne automotive paint systems, the intermediate coating (primer-surfacer) plays a critical bridging role. It needs to fill substrate imperfections, provide good interlayer adhesion, and offer a smooth foundation for the topcoat. To achieve these functions, intermediate coatings often contain high pigment and filler loadings. However, the resulting challenges — high viscosity, easy settling, and poor dispersion stability — have long been a headache for formulators. How can we achieve efficient dispersion and long-term stability without compromising workability and storage stability?

High filler loading in intermediate coatings means a vast specific surface area that needs to be effectively wetted and encapsulated by resins and additives. Insufficient dispersion leads to low grinding efficiency, difficulty in achieving target fineness, poor gloss, and even post-storage coarsening. Inadequate stabilization after dispersion directly causes in-can settling, application sagging, and uneven coating performance. Traditional dispersion approaches often struggle to balance "viscosity reduction" with "anti-settling," or sacrifice long-term stability for cost.

Addressing the specific needs of solvent-borne automotive intermediate coatings, Anjeka Technology offers a comprehensive range of dispersant solutions — from general-purpose to specialty — designed to enhance intermediate coating performance and quality.

1. Universal Choice for High-Filler Systems: Balancing Economy and Performance

Anjeka 6500-50 & Anjeka 6402: These two products are classic choices for high-filler systems. Anjeka 6500-50 provides effective viscosity reduction with cost efficiency. Anjeka 6402, while also delivering effective viscosity reduction, stands out with excellent anti-settling performance — making it more suitable for applications with higher storage stability requirements. Both offer reliable and cost-effective solutions for the fundamental dispersion and stabilization needs of intermediate coatings.

2. Advanced Technology: Controlled Free Radical Polymerization (CFRP)

Anjeka 6182: Synthesized via Controlled Free Radical Polymerization (CFRP), this polymeric dispersant represents a more advanced dispersion technology direction. Its structure can be specifically designed for broad compatibility with various resin systems (acrylic, polyester, epoxy, etc.). This makes it particularly suitable for the production of Resin-Free Pigment Concentrates (RFPC), offering greater formulation flexibility and color matching efficiency. For customers pursuing high performance, broad compatibility, and modernized production processes, Anjeka 6182 is an ideal choice.

3. Key Pigment Optimization: Ensuring Color and Performance

While intermediate coatings are primarily filler-oriented, their color stability and color development (e.g., grays, yellows) remain equally important. Anjeka offers specialized dispersants for different pigment systems:

• Titanium Dioxide (R996): Anjeka 6110A is recommended for 2K PU systems.
• Carbon Black (FW200, Raven5000, etc.): Anjeka 6050 has been validated to deliver excellent gloss and jetness in 1K CAB or 2K PU systems.
• Organic Pigments (Phthalocyanine Blue, Red, Yellow, etc.): Anjeka 6176, Anjeka 6040, and others demonstrate outstanding performance across a variety of organic pigments and systems (1K CAB, 2K PU), ensuring color saturation and stability.
• Special Function Requirements (e.g., PE Primers / Putties): Anjeka 6300A — this acid-functional polyester copolymer dispersant significantly reduces grinding viscosity in systems requiring stable inorganic pigments (especially TiO₂). Due to its anionic nature, it is particularly suitable for acid-catalyzed systems such as certain PE primers and putties.

1. Define Your Primary Goal

Is viscosity reduction your priority to improve application performance? Or anti-settling to ensure storage stability? Are you prioritizing cost-effectiveness or top-tier performance? This determines whether to choose between 6500-50/6402 or evaluate advanced products like 6182.

2. Analyze Your Pigment Composition

If your formulation contains specific key pigments (e.g., certain carbon blacks, organic color pastes), refer to Anjeka's pigment-dispersant matching guide to make targeted selections and avoid color issues.

3. Conduct Side-by-Side Testing

Select 2–3 potential dispersants and run parallel grinding and testing in your actual resin system and pigment formulation. Compare fineness, viscosity, gloss, storage stability, and cost — let data drive your decision.

4. Follow Addition Guidelines

As per product guidelines, dispersants should typically be added before grinding for optimal performance.