Cellulose products are derived from natural cotton pulp or wood pulp by etherification. Different cellulose products use different etherifying agents. Hypromellose HPMC uses other types of etherifying agents (chloroform and 1,2-epoxypropane) , while hydroxyethyl cellulose HEC uses Oxirane etherifying agents. Hydroxyethyl cellulose can be used as thickener in real stone paint and latex paint. Because of its large amount of aggregate, specific gravity, precipitation, it needs to add thickening agent to increase its viscosity, in order to meet the needs of construction spray viscosity, and improve its storage stability, and to achieve a certain strength. To achieve good strength, good water resistance and weather resistance, the selection of raw materials and formulation design is very important.
In general, the amount of high-quality real stone paint emulsion will be higher. For example, a ton of real stone paint may contain 300 kg of pure acrylic emulsion and 650 kg of natural colored stone sand. When the solid content of the emulsion is 50% , the volume of the 300 kg emulsion after drying is about 150 litres, 650 Kg of sand is about 228 litres. 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 irregular in shape, under the condition of a certain particle size distribution, after drying the real stone paint may be in the CPVC (critical pigment volume concentration) about. For thickener, if proper viscosity of cellulose is selected, a relatively complete and dense film can be formed to meet the three major performance requirements of the real stone paint. If the content of the emulsion is low, it is recommended to use a higher viscosity of cellulose as a thickener (e. g. 100,000 viscosity) , especially after the price of cellulose increases, which can reduce the amount of cellulose used, also can let the performance of real stone paint more superior. Some manufacturers of low-cost real stone paints have replaced hydroxyethyl cellulose with hypromellose because of cost and other considerations. Compared with the two kinds of cellulose, hydroxyethyl cellulose has better water-holding capacity, does not lose water-holding capacity due to gel at high temperature, and has certain mildew resistance. For the sake of performance, it is recommended to use 100,000 viscosity hydroxyethyl cellulose as thickener of the real stone paint.
Post time: Jul-24-2023