Influence of cellulose ether on ceramic tile adhesives

Influence of cellulose ether on ceramic tile adhesives

Usually when we judge the performance of a ceramic tile adhesive, in addition to paying attention to its operating performance, anti-sliding ability, but also pay attention to its mechanical strength and opening time. Cellulose ether in ceramic tile glue in addition to affect the rheological properties of porcelain glue, such as smooth operation performance, stick knife situation, but also on the mechanical properties of ceramic tile glue has a strong influence

Cement-based ceramic tile glue is currently the largest application of special dry mixing mortar, which is a kind of cement as the main cementing material and supplemented by gradation of aggregate, water retention agent, early strength agent, latex powder and other organic or inorganic admixtures. Usually used only with water mixing, compared with ordinary cement mortar, can greatly improve the bonding strength between the finishing material and the base material, has good anti-slip and has excellent water resistance, heat resistance and freezing-thawing cycle advantages, mainly used for pasting building interior and exterior wall tiles, floor tiles and other decorative materials, It is widely used in the decoration of walls, floors, bathrooms, kitchens and other buildings. It is the most widely used ceramic tile bonding material.

2, the influence of the opening time of ceramic tile glue

When rubber powder and cellulose ether co-exist in wet mortar, some data models show that rubber powder has stronger kinetic energy to adhere to cement hydration products, and cellulose ether exists more in the gap fluid, which affects the viscosity and setting time of mortar more. The surface tension of cellulose ether is larger than that of rubber powder, and the enrichment of more cellulose ether at mortar interface is beneficial to the formation of hydrogen bonds between the base plane and cellulose ether.

Moisture evaporation from in the wet mortar, mortar, cellulose ether in the surface enrichment, 5 minutes can form a membrane on the surface of the mortar, will reduce the evaporation rate of follow-up, with more water from the slurry thick part of the move to the mortar layer is thinner, open points partly dissolved when the initial formation of the membrane, the migration of water can bring more enrichment of cellulose ether in the mortar on the surface.

Thus, KimaCell cellulose ether film formation on the surface of mortar has a great impact on the performance of mortar, 1) the film formed is too thin, will be dissolved twice, unable to limit the evaporation of water, reduce the strength. 2) the film formed is too thick, the concentration of cellulose ether in the slurry clearance liquid is high, and the viscosity is large. When the ceramic tile is pasted, it is not easy to break the film on the surface. It can be seen that the film forming performance of cellulose ether has a great influence on the opening time. The type of cellulose ether (HPMC, HEMC, MC, etc.) and degree of etherification (degree of substitution) directly affect the film forming performance of cellulose ether, to the hardness and toughness of the film.

3, the influence of drawing strength

Cellulose ether not only endows mortar with all the above beneficial properties, but also delays the hydration kinetics of cement. This retarded effect is mainly due to the adsorption of Kimacell cellulose ether molecules on various mineral phases in the cement system being hydrated, but it is generally agreed that cellulose ether molecules are mainly adsorbed on hydration products such as C-S-H and calcium hydroxide, and rarely adsorbed on the original mineral phase of clinker. In addition, cellulose ether reduces ions (Ca2+, SO42-,...) due to increased viscosity of pore solution. Activity in pore solution, which further retards the hydration process.

Viscosity is another important parameter, which represents the chemical properties of Kimacell cellulose ether. As mentioned above, viscosity mainly affects water retention capacity, and also has a significant impact on the workability of fresh mortar. However, the experimental study found that the viscosity of cellulose ether had almost no effect on the hydration kinetics of cement. Molecular weight has little influence on hydration, and the largest difference between different molecular weights is only 10min. Therefore, molecular weight is not the key parameter to control cement hydration.