Cellulose ether in tile adhesive and emulsion powder - Supply Drymixed mortar Additives and Cellulose Ethers - VIT Chemical Additives Ltd (2025)

Tile adhesive

Tile adhesive is a mixture composed of cement as the main cementitious material, supplemented by graded aggregates, water retention agents, early strength agents, latex powder and other organic or inorganic admixtures. It is usually mixed with water before use. Compared with ordinary cement mortar, it can greatly improve the bond strength between the facing material and the substrate, has good anti-slip properties, excellent water resistance, heat resistance and resistance to freeze-thaw cycles, and is mainly used for sticking decorative materials such as interior and exterior wall tiles and floor tiles. It is widely used for interior and exterior walls, floors, bathrooms, kitchens and other architectural facing and decorative places.

Tile adhesive should not only focus on workability and anti-slip properties, but also on open time and mechanical strength. When powdered glue and cellulose ether coexist in the mortar, the powdered glue has a strong kinetic energy to adhere to the hydration products of cement, while the cellulose ether is more present in the gap liquid, affecting the viscosity and setting time of the mortar.

The influence of cellulose ether:

01 Water retention

As the water in the mortar evaporates, the cellulose ether accumulates on the surface, forming a film on the mortar surface within 5 minutes, which slows down subsequent evaporation. As more water migrates from the thicker parts of the mortar to the thinner parts, the migration of water causes more cellulose ether to accumulate on the surface of the mortar, thereby providing good water retention and workability for the fresh mortar, especially for wetting areas.

This property ensures that the hydration reaction proceeds smoothly, preventing excessive water absorption by the substrate and evaporation of surface water.

02 Film-forming properties

The film formed by the cellulose ether on the surface of the mortar has a significant impact on the performance of the mortar. If the film formed is too thin, it will dissolve again and cannot limit water evaporation, reducing strength. If the film formed is too thick, the cellulose ether will have a high concentration in the mortar gap liquid and the viscosity will be high. When tiles are pasted, it is not easy to break the film on the surface.

It can be seen that the film-forming properties of the cellulose ether have a significant effect on the open time. The type of cellulose ether (HPMC, HEMC, etc.) and the degree of etherification (degree of substitution) directly affect the film-forming properties of the cellulose ether, in terms of the hardness and toughness of the film.

03 Retarding effect

In addition to imparting the above-mentioned beneficial properties to the mortar, cellulose ethers also retard the hydration kinetics of the cement.

This retarding effect is mainly due to the fact that the cellulose ether molecules adsorb on the hydration products such as C-S-H and calcium hydroxide that are undergoing hydration, and that the cellulose ether reduces the mobility of ions (Ca2+, SO42-, etc.) in the solution due to the increased viscosity of the solution, thereby further retarding the hydration process.

The effect of latex powder:

01Improves cohesion and flexibility

In a wet mixing state, powdered latex can change the consistency and smoothness of the system. It can improve the cohesion of the mortar and provide the adhesive force of a smooth and dense surface layer after drying. It can also improve the interfacial interaction between sand and gravel and air holes. When the amount added is guaranteed, the powdered latex will form a film at the interface, making the tile adhesive flexible, reducing the elastic modulus, largely absorbing thermal deformation stress, and also providing water resistance when exposed to water later.

The flexibility and rigidity of the powder can generally be determined by its glass transition temperature. If the glass transition temperature is below 0°C, the powder is flexible. For tile adhesives, it is necessary to choose a powder with relatively good adhesion.

March 24, 2025