How to Add Hydroxyethyl Cellulose to Coatings

Adding Hydroxyethyl Cellulose (HEC) to coatings is a common practice aimed at improving the rheological properties, suspension stability and film-forming properties of coatings.

1. Choose the Right Hydroxyethyl Cellulose

choose the right HEC product based on the type of coating and the expected performance. The properties of HEC, such as molecular weight, degree of substitution (DS), substitution uniformity (MS) and viscosity, will affect the final coating performance. For low-viscosity coatings, such as primers, low-viscosity HEC can be selected, while high-viscosity HEC is suitable for products that require higher thixotropy, such as high-build coatings.

2. Pre-dispersion Process

Before adding HEC to the coating formulation, it is recommended to pre-disperse it. Pre-dispersion can be done in water or solvent, depending on the matrix of the coating. Usually, HEC is slowly sprinkled into the stirred water or solvent first, avoiding adding too much at one time to avoid agglomeration. The stirring speed should be moderate, both to ensure that the HEC can be evenly dispersed and to prevent the introduction of too much air due to too fast stirring.

Steps:

Prepare the container: Choose a clean container and add an appropriate amount of water or solvent.

Slow stirring: Start stirring slowly and then gradually add HEC.

Continuous stirring: Gradually increase the speed during stirring to ensure that the HEC is fully dispersed and forms a uniform dispersion. Usually stirring is required for 30 minutes to 2 hours, depending on the dissolution rate of HEC and the required viscosity.

3. Main ingredient mixing

Add the pre-dispersed HEC solution to the main ingredients. This process needs to be carried out under low-speed stirring to prevent the generation of bubbles and the destruction of HEC. At this time, other additives (such as thickeners, anti-settling agents, defoamers, etc.) can be added at the same time as required.

Steps:

Reduce the stirring speed: Lower the stirring speed in the main ingredients.

Slowly add HEC solution: Slowly pour the pre-dispersed HEC solution to avoid the formation of vortices and the introduction of bubbles.

Uniform mixing: Continue stirring until the coating system is uniform. At this time, pay attention to controlling the temperature to avoid overheating and causing HEC degradation.

4. Performance adjustment

The addition of HEC will significantly change the viscosity and rheological properties of the coating, so the coating needs to be appropriately adjusted after addition. The final performance of the coating can be adjusted to meet specific application requirements by adding thickeners, thickeners, solvents, etc.

Adjustment method:

Viscosity measurement: Use a viscometer to measure the viscosity of the coating to ensure that the design requirements are met.

Leveling performance test: Observe the leveling performance of the coating to determine whether further adjustment is needed.

Anti-settling test: Detect the suspension stability of pigments and fillers in the coating to ensure that the addition of HEC does not cause sedimentation problems.

5. Packaging and storage

After the performance adjustment is completed, the coating should be packaged and stored as soon as possible. Care should be taken to keep the coating sealed to prevent water evaporation and environmental pollution. At the same time, the storage temperature should be moderate to avoid the impact of high or low temperature environments on the performance of the coating.

6. Precautions

Dissolution time: It takes a certain amount of time for HEC to completely dissolve. It is usually necessary to wait for 24 hours before performing performance testing to ensure that HEC is fully functional.

Formula stability: There may be differences between different brands and models of HEC, so when selecting a new model, a small batch test should be carried out to ensure its compatibility with the coating system.

Environmental protection and safety: Wear protective equipment during operation to avoid inhalation of dust or contact with skin. At the same time, pay attention to environmental regulations and properly dispose of waste.

Adding hydroxyethyl cellulose to coatings is a delicate process operation that requires consideration of many factors. Selecting the right HEC product, adequate pre-dispersion, scientific mixing of the main ingredients, and fine performance adjustments are all key steps to ensure the final quality of the coating. Correct operation can not only improve the workability and appearance of the coating, but also improve its service life and performance stability.