Redispersible latex powder products are water-soluble redispersible powders, which are divided into ethylene/vinyl acetate copolymers, vinyl acetate/tertiary carbonate copolymers, acrylic copolymers, etc., and the powders produced after spray drying are bonded Agent, using polyvinyl alcohol as a protective colloid. Since the redispersible latex powder has high bonding capacity and unique properties, because of its outstanding bonding strength, it improves the flexibility of the mortar and has a longer opening time, giving the mortar excellent alkali resistance and improving the adhesion of the mortar In addition to sexual adhesion, flexural strength, water resistance, plasticity, wear resistance and workability, it has more flexibility in flexible crack-resistant mortar. Its role in industrial applications is critical.
Mechanism of action
The first step in the production of redispersible polymer powder is the production of polymer dispersions, also known as emulsions or latexes. In this process, water-emulsified monomers (stabilized by emulsifiers or macromolecule protective colloids) react with the initiator to start emulsion polymerization. Through this reaction, the monomers are connected to form long-chain molecules (macromacromolecules). That is polymer. During this reaction, monomer emulsified droplets are transformed into polymer "solid" particles. In this polymer emulsion, the stabilizer on the surface of the particles must prevent the latex from coalescing under any circumstances and thus causing an unstable state. Then by adding different additives to make a mixture for spray drying, and then add protective colloid and anti-caking agent to make the polymer form a free flowing powder that can be redispersed in water after spray drying.
The redispersible latex powder is distributed in the dry powder mortar that is evenly mixed. After the mortar is mixed with water, the polymer powder is re-dispersed into the newly mixed mortar and emulsified again; the internal pores are free due to the hydration of the cement, surface evaporation, and/or the absorption of the base layer The continuous consumption of water causes the latex particles to dry in water to form a continuous film that is insoluble in water. This continuous film is formed by fusing single dispersed particles in the emulsion into a homogenous body. In order for the redispersible powder to form a film in the hardened mortar, it must be ensured that its minimum film forming temperature is lower than the curing temperature of the modified mortar.