Paint additives are used in very small quantities, but can significantly improve the properties of paints, so has become an indispensable part of paints – Hydroxyethyl Cellulose in water-based paints. The thickener is a rheological additive. It not only can thicken the paint and prevent sagging in construction, but also can give the paint excellent mechanical properties and storage stability. For the water-based paint with low viscosity, Hydroxyethyl Cellulose is a very important class of additives.
Cellulose ether thickeners have been used for ages and have many varieties, such as Methyl Cellulose (MC), Carboxymethylcellulose (CMC), Hydroxy Ethyl Cellulose (HEC) and Hydroxypropyl Methylcellulose (HPMC). They were once the mainstream of thickeners, of which the most commonly used is Hydroxyethyl Cellulose (HEC).
Cellulose ether thickeners have high thickening efficiency, especially for thickening of the aqueous phase. The advantages are fewer restrictions on the paint formulations, wide application, and large range of pH value available. However, the disadvantages are poor leveling property, many spattering phenomena during roller painting, poor stability, susceptible to microbial degradation and so on. Due to its low viscosity under high shear conditions, and high viscosity under static and low shear conditions, after the coating is completed, the viscosity will increase rapidly, on one hand preventing from sagging, but on the other hand resulting in poor leveling property.
In the mastic coating, hydroxyethyl cellulose with high viscosity and larger thixotropy should be selected, while in plain latex paints with high pigment volume concentration (PVC), the compound of low-viscosity and high-viscosity hydroxy ethyl cellulose or the acrylic emulsion thickener can be selected. The compound use of the thickener has better effects than used alone.