Cellulose products are made from natural cotton pulp or wood pulp by etherification. Different cellulose products use different etherifying agents. Hydroxyethyl cellulose (HEC) uses ethylene oxide, and hydroxypropyl methylcellulose (HPMC) uses other types of etherifying agents (chloromethane and propylene oxide).
Hydroxyethyl cellulose can be used as thickener in stone paint and latex paint.
Due to the large amount of aggregate, large ratio and easy to precipitate, it is necessary to add thickener to increase its viscosity, so as to meet the needs of construction spraying, improve its storage stability and achieve a certain strength.
In order to achieve good strength, water resistance and weather resistance, the selection of raw materials and the design of formula are very important.
Under normal circumstances, the quality of genuine lacquer emulsion will be relatively high.
For example, a ton of real stone paint may contain 300kg pure acrylic emulsion and 650kg natural colored stone sand. When the solid content of emulsion is 50%, the volume of 300kg emulsion after drying is about 150 liters, and the volume of 650kg sand is about 228 liters.
That is to say, at this time, the PVC (pigment volume concentration) of the real stone paint is 60%, because the particles of the colored sand are large and the shape is irregular, under the condition of a certain particle size distribution, the dried real stone paint may be around CPVC (Critical pigment volume concentration). As far as thickener is concerned, if cellulose with proper viscosity is selected, stone paint can form a relatively complete and dense paint film to meet the three major performance requirements of stone paint.
If the content of genuine lacquer emulsion is low, it is suggested that cellulose with high viscosity should be used as thickening agent (for example, 100 thousand viscosity), especially after the price rise of cellulose, which can reduce the use of cellulose and make the performance of real stone paint better.
Some economical stone paint manufacturers replace hydroxyethyl cellulose with hydroxypropyl methylcellulose due to cost and other factors.
In comparison with the two cellulose, hydroxyethyl cellulose has better water holding capacity, and does not lose water retention due to gelation at high temperature, and has a certain mildew resistance. For the sake of performance, it is recommended to use hydroxyethyl cellulose with a viscosity of 100000 as the thickener of real stone paint.