Application of HEC in latex paint

Hydroxyethyl Cellulose (HEC) is a non-ionic water-soluble polymer, which is chemically modified from natural cellulose. It has good water solubility, thickening, water retention and film-forming properties. In latex paint, hydroxyethyl cellulose is an important additive and is widely used in interior and exterior wall coatings to thicken, stabilize, disperse, suspend and improve workability.

1. Main properties of hydroxyethyl cellulose

Good water solubility: HEC can be quickly dissolved in cold water and hot water to form a transparent and uniform colloidal solution.

Obvious thickening effect: It can effectively increase the viscosity of latex paint and improve its workability and leveling.

Strong suspension stability: It can prevent the sedimentation of pigments and fillers and improve the storage stability of latex paint.

Good film-forming properties: It helps to form a dense coating film and improve the fullness and flatness of the paint film.

Strong compatibility: It has good compatibility with a variety of emulsions, pigments, fillers and other additives. 

2. The role of hydroxyethyl cellulose in latex paint

Thickener: Control the rheological properties of the paint, prevent dripping and splashing, and improve the performance of brushing and rolling.

Water-retaining agent: Prevent the loss of water in the paint during construction and improve the film-forming quality during the drying process.

Stabilizer: Improve the dispersibility and stability of the emulsion and pigment filler in the formula to prevent stratification and agglomeration.

Improve construction performance: Improve lubricity and construction smoothness to make brushing smoother and more natural.

3. Usage method

3.1. Dry powder direct dispersion method

Applicable to production conditions with high-speed dispersion equipment:

Add the specified amount of clean water to the mixing tank;

Start high-speed stirring and gradually add HEC dry powder;

Continue stirring for 15-30 minutes until HEC is fully wetted and dispersed;

Stand for 1-2 hours (or longer) to allow it to fully swell;

Stir again until it is completely dissolved to form a uniform and transparent viscous solution;

Add other emulsions, pigments, additives, etc. to make latex paint.

3.2. Pre-gelatinized mother liquor method

Suitable for mass production, easy to operate and measure:

First wet HEC with water;

Slowly heat to 60-70℃ under low-speed stirring to promote its dissolution;

Or activate the dissolution process by adding a small amount of alkali (such as ammonia water);

After dissolution, a uniform pre-gelatinized mother liquor is formed, which can be added to latex paint as needed.

4. Dosage recommendation

The amount of hydroxyethyl cellulose added to latex paint is generally 0.2%~1.0% (based on the quality of the finished product), which is adjusted according to the required viscosity and construction performance.

The viscosity (generally based on 2% aqueous solution) has a wide range of choices, ranging from tens of mPa·s to hundreds of thousands of mPa·s. Commonly used ones are:

30,000~60,000 mPa·s: for medium and high viscosity latex paints;

100,000~200,000 mPa·s: for thick paints or paste paints.

5. Precautions

The order of dispersion is important: the dry powder must be evenly dispersed to avoid local agglomeration and difficulty in dissolution.

Prevent caking: When adding HEC, high-speed stirring should be maintained to prevent powder agglomeration from affecting dissolution.

Storage stability: HEC solution should be stored at room temperature to avoid long-term exposure to high temperature or strong acid and alkali environment.

Compatibility test: The compatibility of HEC with emulsions and additives from different manufacturers may vary, and the formula should be determined after the test.

As an efficient, economical and environmentally friendly water-soluble thickener, the application of hydroxyethyl cellulose in latex paint provides the product with good rheological control and construction experience. By reasonably selecting the viscosity grade, controlling the addition method and formula ratio, the performance of latex paint can be significantly improved. With the continuous pursuit of environmental protection and performance in the architectural coatings industry, the application value of HEC will be further highlighted.