In industrial paint production, pigment dispersion directly determines the final coating quality. When pigments are unevenly distributed, the film may show streaks, roughness, or sedimentation. In contrast, good dispersion ensures accurate color, smooth film texture, and long-term stability. Proper control of dispersion not only enhances appearance but also optimizes production efficiency and cost performance.
FACTORS AFFECTING PIGMENT DISPERSION
Pigment properties
Particle size, surface area, and degree of agglomeration are key parameters influencing dispersion. Smaller pigment particles offer a larger surface area but require higher grinding energy. Additionally, their hydrophilic or hydrophobic nature affects compatibility and wetting in resin or solvent systems.
Dispersing agent
A dispersant acts as an additive that reduces interfacial tension between pigment and liquid phases. It promotes wetting and prevents re-agglomeration of pigment particles. Two common stabilization mechanisms are electrostatic repulsion and steric hindrance. Choosing the right dispersant is essential to achieve optimal pigment dispersion.
Resin and solvent
The resin–solvent system defines the overall viscosity of the formulation, which directly impacts shear force during grinding. High viscosity limits pigment movement and results in poor dispersion. Conversely, a balanced solvent system improves pigment wetting, grinding efficiency, and color stability.
Equipment and process control
High-speed dispersers, bead mills, or intensive mixers are vital in mechanical dispersion. Parameters such as rotation speed, grinding duration, temperature, and feed sequence must be properly optimized to maintain consistent pigment quality.
STEPS TO EFFECTIVE DISPERSION CONTROL
Selecting the appropriate dispersant
Each pigment type requires a specific dispersant chemistry. Inorganic pigments such as titanium dioxide or iron oxides often need short-chain dispersants, while organic pigments or carbon black require polymeric dispersants with strong ionic functionality. Compatibility between the dispersant and binder system ensures long-term stability and uniform dispersion.
Pre-mixing and dispersion
The pre-mixing stage ensures complete wetting of pigment particles in resin or solvent. Agitation speed typically ranges from 500–1500 rpm for 15–30 minutes, depending on the viscosity of the batch. This step prevents dry agglomerates and promotes uniform distribution before the main grinding stage.
During grinding, mechanical energy is converted into shear force to break down pigment clusters. Equipment such as high-speed dispersers or bead mills is commonly used. The dispersion fineness is evaluated using a Hegman gauge, typically reaching 10–25 µm depending on the coating system.
Testing and stabilization
After grinding, the mixture should be examined under a microscope or with a particle size analyzer. If sedimentation occurs, stabilizing additives such as BYK-110 or TEGO Dispers 688 can be added. This step ensures long-term homogeneity and storage stability of the coating.
System optimization
Each coating system—PU, epoxy, acrylic, or water-based—has unique interactions with pigments and dispersants. Therefore, small-scale trials should be performed to fine-tune the formulation before full-scale production. This minimizes variability and ensures consistent coating performance across batches.
VICHEM – AUTHORIZED DISTRIBUTOR OF CERTIFIED CHEMICAL ADDITIVES IN VIETNAM
Vichem is the official distributor of Zealan pigments in Vietnam. We not only provide quality products but also provide after-sales services that meet international standards. Services include:
- Technical consultation: Expert guidance to help customers select the most suitable additives for their specific coating systems.
- Color-matching support: Vichem’s specialists conduct laboratory pigment tests to ensure formulations meet design and color standards.
- Application assistance: On-site technical support to help customers integrate additives efficiently into production lines.
For more information, please contact us via the following channels:
📞 Hotline: 08 1790 1790
📧 Email: contact@vichem.vn
🔎 LinkedIn: Vichem JSC
🌐 Website: www.vichem.vn
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