Views: 2 Author: Site Editor Publish Time: 2022-11-28 Origin: Site
Can hydroxypropyl methylcellulose replace hydroxyethyl cellulose in real stone paint?
Cellulose products are all derived from natural cotton pulp or wood pulp and are produced through etherification. Different cellulose products use different etherifying agents, the etherifying agent used in hydroxyethyl cellulose is ethylene oxide, and the etherifying agent used in hydroxypropyl methylcellulose is other types of etherifying agents (methane chloride and epoxy propane).
In real stone paint and latex paint, hydroxyethyl cellulose can be used as a thickener.
Real stone paint is easy to precipitate because of its large amount of aggregate and large specificity. It is necessary to add a thickener to increase its viscosity to meet the viscosity required for spraying during construction, improve its storage stability, and achieve a certain strength.
If you want real stone paint to achieve good strength, good water resistance and weather resistance, the selection of raw materials and the design of the formula are very important.
Under normal circumstances, the amount of emulsion used in high-quality real stone paint will be relatively high.
For example, in a ton of real stone paint, there may be 300kg of pure acrylic emulsion and 650kg of natural colored stone sand. When the solid content of the emulsion is 50%, the volume of 300kg of emulsion after drying is about 150 liters, and the volume of 650kg of sand is about 228 liters.
That is to say, the PVC (pigment volume concentration) of the real stone paint is 60% at this time, because the particles of colored sand are large and irregular in shape, and under the condition of a certain particle size distribution, the dried real stone paint may be in the CPVC (critical mass concentration). Pigment volume concentration) approx. As far as the thickener is concerned, if you choose cellulose with an appropriate viscosity, the real stone paint can form a relatively complete and dense paint film to meet the three major performance requirements of the real stone paint.
If the content of the real stone paint emulsion is low, it is recommended to use cellulose with higher viscosity as a thickener (such as 100,000 viscosity), especially after the price of cellulose increases, which can reduce the amount of cellulose used and make the real stone The performance of the paint is better.
Some economical real stone paint manufacturers use hydroxypropyl methylcellulose instead of hydroxyethyl cellulose for cost and other factors.
Compared with the two kinds of cellulose, hydroxyethyl cellulose has better water retention, will not lose water retention due to gelatin at high temperature, and has certain mildew resistance. For performance considerations, it is recommended to use hydroxyethyl cellulose with a viscosity of 100,000 as a thickener for real stone paint.