The Role of Redispersible polymer Powder in External Wall Insulation System

  1. Effect on fresh mortar

Extend the work time and improve water retention performance to ensure the hydration of cement and improve workability;

  • Effect on hardened mortar

Good adhesion to polystyrene board and other substrates, excellent flexibility and impact resistance, excellent water vapor transmission, good water repellency and weatherability.

Traditional bonding materials has a great hidden danger to the safety of building tile bonding. There have been reports of smashing of external wall tiles and causing casualties. As exterior wall tiles(generally stone bricks and vitrified tiles), they are required to have a lower porosity to obtain lower water absorption, frost resistance and the like. Conventional cement mortars are clearly insufficiently bonded. On the other hand, the traditional cement mortar even if some glue is added( the type of glue is mostly water-soluble polymer adhesive, which is brittle under the alkaline action of cement), although a higher initial bond strength can be obtained, the cement mortar has very low flexibility and cannot absorb the internal stress generated between the tile and the substrate under severe natural environmental conditions(high and low temperature, freeze-thaw cycle etc.) which simply relies on increasing the initial bond strength to resist internal stress. The “anti” approach has been ineffective by countless bonding, and the accident of tile peeling has proved to be inappropriate. The adoption of a flexible “release” principle is a more scientific and reasonable choice. The choice of a suitable polymer is the key to the flexible of the tile adhesive to maintain durability.  dispersible polymer powders are all polymers containing vinyl blocks. Since the vinyl group is randomly embedded in the vinyl acetate, the dispersible polymer powder is imparted with a permanent internal plasticizing effect and good saponification resistance. Compared with VAC/VEOVA, VAC/E has excellent bonding effect especially in harsh environments where the temperature changes periodically.

Although the deformability test of tile adhesive was set as an optional item, this indicator test allowed the flexibility index of the tile adhesive to be qualified. The redispersible polymer powder with low glass transition temperature has higher deformability under the condition that the cement is completely hydrated and the polymer content is high.