2. Redispersible polymer powder
Redispersible rubber powder is made of special polymer lotion through spray drying. During the processing, protective colloid and anti hardening agent become indispensable additives. The dried rubber powder is some 80~100mm spherical particles gathered together. These particles can be soluble in water and form a stable dispersion slightly larger than the original lotion particles. This dispersion will form a film after dehydration and drying. This film is irreversible like the film formation of ordinary lotion, and will not disperse into a dispersion when encountering water.
Redispersible rubber powder can be divided into styrene butadiene copolymer, tertiary ethylene carbonate copolymer, ethylene acetic acid copolymer, etc., and on this basis, organic silicon and vinyl laurate can be grafted to improve the performance. Different modification measures make the redispersible rubber powder have different properties such as water resistance, alkali resistance, weather resistance and flexibility. It contains vinyl laurate and organic silicon, which can make the rubber powder have good hydrophobicity. Highly branched ethylene tertiary carbonate has low Tg value and good flexibility. The application of these powders in mortar has a retarding effect on the setting time of cement, but the retarding effect is smaller than that of the direct application of similar lotion. In contrast, the retarding effect of styrene butadiene is greater than that of ethylene vinyl acetate. If the dosage is too small, the improvement of mortar performance is not obvious.