Redispersible Polymer Powder
Redispersible polymer powder (RDP) is a powdery thermoplastic resin material made of polymer emulsion through a series of processes such as high temperature and high pressure, spray drying, and surface treatment. When mixed with water, these powdered organic binders can be redispersed in water to form new emulsions with essentially the same properties as the original copolymer emulsion.
Adding redispersible polymer powder into the mortar can increase the cohesiveness, cohesiveness and flexibility of the mortar. First of all, it can improve the water retention of the mortar, form a thin film, and reduce the evaporation of water. Second, it can improve the bond strength of mortar.
In 1953, the German Wacker Hemie invented RDP redispersible polymer powder, which made it possible to produce polymer modified dry-mixed mortar. The history of redispersible polymer powder is only more than 50 years. In 1953, the world's first practical redispersible latex powder was invented in Germany. With the continuous innovation and progress of the production process of follow-up products, a series of achievements have been made, and a series of products have been developed in combination with follow-up applications.
The world's first redispersible polymer powder is vinyl acetate homopolymer powder. However, this polymer powder can only be used in non-alkaline systems, because esters or polymers with ester bonds react to form free alcohols or acid salts under alkaline conditions, resulting in sudden changes in performance, from non-water-soluble Sex becomes water soluble, i.e. loss of desired flexibility due to increase in glass transition temperature, or for other reasons. In 1960, ethylene-vinyl acetate copolymer powder (EVA) was successfully produced, mainly using ethylene, an unsaponifiable organic monomer, to internally plasticize the redispersible polymer powder, and significantly improve the polymer powder. body flexibility. This polymer powder can be used in the alkali system of Portland cement.