Application performance
(1) Improve the bonding strength: the latex powder at the interface forms a film
(2) Improve cohesion: film formation on the capillary wall and film formation at micro-cracks
(3) Improve the airtightness and water resistance of mortar: film formation on capillary walls, film formation at micro cracks, latex powder film is waterproof
(4) Improve the flexibility and deformation ability of the mortar: latex powder is a low elastic modulus to change the rigidity of the cement base, and the latex powder bridges the mortar to supplement micro-cracks
(5) Improve mortar workability: ball effect of latex powder particles, air-entraining effect of latex powder emulsion
(6) Influence on the mechanical properties of mortar: reduce the compressive strength and elastic modulus; appropriately improve the tensile strength of mortar; appropriately increase the flexural strength of cement mortar
(7) In the mortar system, the performance of the mortar varies with the content of latex powder, and the amount of cement has a great influence on the performance of the mortar. Properly increasing the amount of cement can increase the elastic modulus and water resistance of the latex powder film, but with the amount of cement The increase of will reduce the deformation ability of latex powder film.
When the latex powder content is high, the material is flexible and has strong deformation resistance. This type of material can be used as waterproof mortar, flexible tile adhesive, anti-crack plastering mortar, etc.;
When the latex powder content is low, the material is rigid and has high bonding strength. Due to the molecular bond of the rubber powder, it can also have good bonding strength on smooth or flexible substrates. It is used in tile adhesives, benzene Board bonding mortar; in addition, latex powder can increase the cohesion of the material and improve wear resistance. The typical application is self-leveling mortar.
(8) Mechanism of action: a combination of latex powder (features: low elastic modulus, large deformation capacity, swelling and softening when exposed to water, sealing material, low compressive strength, high bond strength, etc.) and cement materials (features: elastic modulus High volume, small deformation capacity, hydraulic materials, porous materials, high compressive strength, low bonding strength, etc.) have their own advantages, which make the bonding performance and durability of the material significantly improved. Tile adhesive is one of the typical applications.
Film forming process: With the loss of water in the mortar (evaporation, substrate absorption, cement hydration), the latex powder particles are close to each other
When the temperature is higher than the minimum film-forming temperature, the polymer film is gradually formed and interlaced with the cement hydrate, so that the mortar obtains the growth of cohesive strength and bonding strength, and finally improves the cement stone structure.
To make the film-forming process of latex powder irreversible, the hydrophilic protective colloid of redispersible rubber powder—polyvinyl alcohol—must be consumed. In an alkaline system, polyvinyl alcohol will be saponified by alkali, and this reaction is irreversible; in a non-alkaline system, polyvinyl alcohol will remain, affecting water resistance. Therefore, the alkaline environment (high pH and ionic strength in the pore solution) of cement-based materials is an important factor for the coalescence of latex particles.