Effect of hydroxypropyl starch ether in mortar

1. Thicken the mortar and increase the anti sagging, anti sagging and rheology of the mortar

For example, in the construction of ceramic tile glue, putty and plastering mortar, especially now mechanical spraying requires high fluidity, especially in gypsum based mortar (mechanical spraying gypsum requires high fluidity, but it will bring serious sagging phenomenon, and starch ether can make up for this defect).

Liquidity and anti sag are often contradictory. The improvement of liquidity will lead to the decline of anti sag. The mortar with rheological properties can well solve such a contradiction, that is, when the external force is applied, the viscosity decreases and the constructability and pumping performance are enhanced. When the external force is withdrawn, the viscosity increases and the sag resistance is improved.

For the increasing trend of ceramic tile area, the addition of starch ether can improve the slip resistance of ceramic tile adhesive.

2. Extended opening hours

For ceramic tile adhesive, it can meet the requirements of special ceramic tile adhesive (Grade E, extended from 20min to 30min, reaching 0.5MPa) for prolonging the opening time.

Surface property improvement

Starch ether can make the surface of gypsum based and cement mortar smooth, easy to apply and good decorative effect. It is very meaningful for plastering mortar and thin-layer decorative mortar such as putty.

Mechanism of starch ether

When the starch ether is dissolved in water, it will be evenly dispersed in the cement mortar system. Because the starch ether molecules have a network structure and are negatively charged, it will absorb positively charged cement particles. As a transition bridge, it can connect the cement, so as to give the slurry a large yield value and improve the anti sagging or anti sliding effect.

Difference between starch ether and cellulose ether:

1. Starch ether can effectively improve the anti sagging and anti sliding properties of mortar. Cellulose ether can only improve the viscosity and water retention of the system, but can not improve the anti sag and anti slip properties.

2. Thickening and viscosity. Generally, the viscosity of cellulose ether is about tens of thousands, while the viscosity of starch ether is hundreds to thousands, but this does not mean that the thickening of starch ether to mortar is not as good as cellulose ether. The thickening mechanism of the two is different.

3. Compared with cellulose ether, starch ether can significantly improve the initial yield value of ceramic tile adhesive, so as to improve its anti slip performance.

4. Air entrainment. Cellulose ether has strong air entrainment, while starch ether has no air entrainment.

5. Molecular structure of cellulose ether. Although both starch and cellulose are composed of glucose molecules, their composition is different. The orientation of all glucose molecules in starch is the same, while that of cellulose is just the opposite, and the orientation of each adjacent glucose molecule is the opposite. This structural difference also determines the difference in the properties of cellulose and starch.

The combination of cellulose ether and starch ether can produce good synergy. The test shows that using starch ether instead of 20% - 30% cellulose ether in mortar can not reduce the water holding capacity of mortar system, and effectively improve the anti sagging and anti sliding capacity.