Troubleshooting Common Issues with Water-Borne Dispersants in Coatings

In water-borne coatings, dispersants are essential for achieving uniform pigment and filler distribution, as well as for preventing sedimentation and particle agglomeration. However, various challenges can occur during their use, potentially compromising coating quality. This article outlines the most common problems encountered with water-borne dispersants and provides practical troubleshooting methods to address them.

1. Poor Dispersion and Pigment Aggregation

During the coating production process, inadequate dispersant performance can result in incomplete dispersion of pigment particles, causing particle aggregation or sedimentation, and affecting the uniformity of the coating.

Troubleshooting :

Check Dispersant Selection: Selecting the appropriate dispersant is crucial. Different types of pigments or fillers require different dispersants. Ensure the dispersant is tailored to the pigment’s surface chemistry and polarity.

Optimize the Dispersion Process: Use high-shear mixing equipment to ensure adequate pigment fragmentation. Adjust the stirring speed and duration during the dispersion process to avoid uneven dispersion.

2. Paint Viscosity Too High

If the paint viscosity is too high, it may cause poor flowability during application, making it difficult to apply. High viscosity can be caused by inappropriate dispersant dosage (either excessive or insufficient), pigment flocculation, or adverse interactions with other additives.

Troubleshooting:

Reduce the dispersant dosage: Excessive dispersant may increase the viscosity of the paint. Reduce the dispersant dosage appropriately according to the formulation requirements.

Adjust other additives: Check the dosage of other additives in the paint, such as thickeners, to avoid interactions with the dispersant that could cause excessive viscosity.

3. Poor Paint Stability and Susceptibility to Settling

Sedimentation is sometimes caused by differences in particle density; physical sedimentation may occur even with adequate dispersant stabilization.

Troubleshooting:

Select a dispersant with good stability: Ensure the dispersant maintains stability during long-term storage to prevent pigment settling.

Improve dispersion: Enhance the dispersion process to ensure complete dispersion of pigment particles. The dispersant dosage can be increased, but it should be adjusted within an appropriate range to avoid affecting other paint properties.

4. Blistering（foaming defects） on the Paint Surface

Incorrectly selected dispersants or inadequate removal of bubbles during the dispersion process can cause blistering on the paint surface, affecting the coating’s appearance.

Troubleshooting:

Optimize the dispersion process: Avoid excessive air incorporation during the dispersion process and use appropriate equipment and techniques to reduce bubbles.

Select an appropriate defoamer: Using a defoamer can effectively reduce foaming. Choose a defoamer that is compatible with the dispersant to avoid affecting the paint’s performance.

5. Dispersant incompatibility with other additives

Water-based paints often use multiple additives, such as thickeners and defoamers. Poor compatibility between the dispersant and these additives can lead to unstable paint performance and even problems such as delamination and gelation.

Troubleshooting:

Select a dispersant with good compatibility: Choose a dispersant with good compatibility with other additives. Experimental testing can be used to determine the compatibility of different additives.

Add other additives gradually: When adding additional additives, ensure each additive is thoroughly mixed before adding the next to avoid the presence of incompatible substances.

6. Unsatisfactory hiding power of the paint

Dispersants not only affect the dispersibility of the paint but also directly impact its hiding power. If the dispersion is not ideal, the pigment’s coverage will be poor, potentially leading to uneven coatings and affecting appearance and performance.

Troubleshooting:

Adjust pigment particle size and dispersion: Ensure the pigment is evenly distributed and has an appropriate particle size within the paint. Use a high-efficiency dispersant to improve pigment dispersibility and enhance the paint’s hiding power.

Improve dispersant selectivity: For paints requiring high hiding power, choose a dispersant that provides excellent dispersion and ensures pigment stability.

The use of water-based anti foaming agent is crucial in the paint production process. Common problems such as poor dispersion, excessive paint viscosity, and poor stability can affect the final paint quality. These issues can usually be effectively resolved by optimizing the dispersion process, adjusting the dispersant dosage, and selecting appropriate additives. However, due to the diversity of paint formulations and production conditions, individual issues may require professional technical assistance. If you encounter difficult-to-solve water-based dispersant problems, Polywill provides a dedicated technical team with extensive experience and technology to provide you with customized solutions to ensure a smooth coating production process and improve product quality.