How to Correctly Add HEC to Latex Paint?

Hydroxyethyl cellulose (HEC), a commonly used nonionic thickener and rheology modifier in latex paint systems, plays a crucial role in improving the viscosity structure, leveling, storage stability, and anti-splatter properties of coatings. The correct addition method directly affects the quality of the paint film and its application performance. The following are key operational points:

I. Selecting the Appropriate Viscosity Grade The appropriate viscosity grade of HEC should be selected based on the type of latex paint. For ordinary interior wall paints, medium to high viscosity grades can be used to balance thickening efficiency and application performance; high-end interior wall paints should use high viscosity grades to achieve better film fullness and anti-splatter properties; exterior wall systems often use it in combination with other types of thickeners to enhance anti-sagging and storage stability. It should be noted that higher viscosity is not always better; the system requirements and cost-effectiveness should be considered comprehensively.

II. Controlling the Appropriate Addition Amount The conventional addition amount of HEC is generally 0.2%–0.6% of the total finished paint volume. The specific dosage needs to be fine-tuned based on pigment volume concentration (PVC), emulsion type, target viscosity, and the synergistic effect of other thickeners. A reasonable addition amount should result in a system with moderate viscosity, good stability, and ideal application leveling.

III. Use an Appropriate Dissolution Method

It is recommended to pre-prepare a water-based HEC stock solution, typically dissolved at a ratio of 1:20 to 1:40 to create a homogeneous, transparent solution. This method helps HEC to fully hydrate, avoids the "fisheye" phenomenon, and facilitates subsequent viscosity adjustment. If dry powder must be added directly, it should be added slowly and evenly under high-speed dispersion conditions, ensuring complete dissolution before contact with the emulsion to prevent localized agglomeration.

IV. Optimize System Compatibility and Process Conditions

To construct an ideal rheological structure, HEC can be compounded with thickeners such as HEUR and ASE to synergistically improve the coating's anti-splatter properties and application feel. Furthermore, the system pH should be controlled within the neutral to slightly alkaline range to avoid viscosity loss due to an acidic environment. Regarding storage stability, it is recommended to use surface-treated HEC products to inhibit viscosity decay during long-term storage or under high-temperature conditions.

In conclusion, the scientific selection of hydroxyethyl cellulose and the standardization of its addition process are important guarantees for achieving high performance and high stability of latex paint, and should be given full attention in actual production.