In the coating industry, pH plays a critical role in determining product quality. The pH value indicates the concentration of hydrogen ions, defining the acidity or alkalinity of a solution. Precise pH control ensures stable coating mixtures, efficient application, and long-lasting film durability. In this article, Vichem explores the importance of pH in coating production. You will learn how to adjust pH to achieve optimal quality.
THE IMPORTANCE OF pH IN COATING PRODUCTION
Modern coatings include water-based, solvent-based, and blended systems. Their main components consist of polymer resins, pigments, fillers, additives, and solvents. Among these, water-based coatings are most affected by pH. The pH value influences stability, coverage, and film durability. Uncontrolled pH can lead to sedimentation or peeling. Proper pH control optimizes the production process, ensuring uniform coating mixtures, easy application, and long-term durability.
HOW pH AFFECTS COATING COMPONENTS
The Secret to Stable Polymer Emulsions
Polymer emulsions form the foundation of water-based coatings like acrylic and polyurethane. The pH ensures even dispersion of polymer particles in water. Low pH creates an acidic environment, reducing the surface charge of polymer particles. This causes collisions, leading to coagulation, separation, or solidification. Conversely, excessively high pH may cause gelation or additive precipitation. The ideal pH range for water-based coatings is 7.8–9.0. This ensures stable emulsions, smooth films, and lasting durability.
Optimizing Pigment and Filler Dispersion
Pigments determine the color and coverage of coatings. Optimal pH promotes uniform pigment dispersion, resulting in vibrant colors. Inappropriate pH causes pigments to clump, leading to sedimentation. This results in dull, uneven colors. Fillers like calcium carbonate dissolveಸ
System: carbonate dissolve in acidic environments, producing CO₂ gas and causing pinholes in the film. Strict pH control ensures aesthetically pleasing and durable coating films.
Enhancing Curing and Film Formation
Two-component coatings, such as epoxy and polyurethane, cure through chemical reactions. Each resin system requires an optimal pH for effective reactions. Incorrect pH alters curing speed, preventing the film from reaching full hardness. This leads to peeling or reduced chemical resistance. For water-based polyurethane, a pH of 7.8–8.3 is ideal. It ensures a tough, durable, and aesthetically pleasing film.
Perfect Adhesion and Surface Protection
The pH directly affects coating adhesion to material surfaces. On metals, low pH accelerates corrosion, causing the coating to peel easily. On wood surfaces, excessively alkaline pH (above 10) causes yellowing or surface degradation. This reduces the coating’s aesthetics and lifespan. Proper pH control protects surfaces and enhances coating durability.
Preventing Bacteria and Ensuring Effective Preservation
Water-based coatings are prone to bacterial and mold growth at near-neutral pH. For long-term preservation, pH is typically adjusted to 8–9. Combined with preservatives, this prevents microbial growth. As a result, the coating mixture remains stable, free from clumping or color changes. This is crucial for coating storage and transportation.
THE GOLDEN pH RANGE FOR COATING SYSTEMS
Each coating system requires a specific pH range for optimal performance:
- Acrylic coating: pH 8.0–9.0 ensures stable emulsions and vibrant colors.
- Polyurethane coating: pH 7.8–8.3 supports uniform curing and durable films.
- Water-based epoxy coating: pH 7.5–8.5 creates tough, resilient films.
- Wall coating: pH 8.0–9.0 offers antibacterial properties and long-term preservation.
- Solvent-based coating: pH has minimal impact.
COMMON MISTAKES WHEN pH IS INCORRECT
Uncontrolled pH leads to serious issues in coating mixtures. Sedimentation occurs due to unstable emulsions or pigments. The coating film may gel or become too thin if thickeners fail. Blistering or pinholes appear due to CO₂ from fillers in acidic conditions. Dull, uneven colors result from poor pigment dispersion. Peeling occurs when pH causes corrosion or surface degradation. Neutral pH leads to foul odors or mold growth.
SECRETS TO ACCURATE pH TESTING AND ADJUSTMENT
To measure pH, manufacturers can use specialized pH meters or litmus paper. However, pH meters require periodic calibration for accurate results. If pH is low, add ammonia or triethanolamine to increase it. If pH is high, use acetic acid to lower it. Add pH adjusters gradually, testing continuously until the desired value is reached. In large-scale production, monitor pH at every stage to minimize risks and ensure product quality.
VICHEM – AUTHORIZED DISTRIBUTOR OF HIGH-STANDARD COATING MATERIALS IN VIETNAM
Vichem is a leading distributor of coating manufacturing materials with standardized pH levels in Vietnam. We not only supply high-quality products but also provide after-sales services that meet international standards. Our services include:
- Technical consultation: Assisting customers in selecting products suitable for their printing technology and intended applications.
- Color matching testing: Vichem’s team of experts conducts color matching tests to ensure printed results align with design standards.
- Practical application support: Partnering with customers to integrate pigments into production lines, ensuring optimal performance.
For more information about our products, please contact us through the following channels:
📞 Hotline: 0817 901 790
📧 Email: contact@vichem.vn
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