Effect of Redispersible Emulsion Powder in Putty


Release time:

2021-02-27

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Redispersible emulsion powder is a thermoplastic resin powder made by spray drying polymer emulsion to remove water.

Effect of Redispersible Emulsion Powder in Putty
 
The redispersible emulsion powder is a thermoplastic resin powder prepared by spray drying the polymer emulsion to remove the water, which can be reduced to the emulsion state after adding water. Because of this characteristic, it has been widely used in the field of single-component JS waterproof coating, polystyrene board bonding mortar for building insulation, flexible surface protective mortar, polystyrene particle insulation coating, tile adhesive, self-leveling mortar, dry mixing mortar, putty and other fields that need to be modified by inorganic cementitious materials. Redispersible latex powder can enhance the strength of the product, in the putty powder and mortar to add redispersible latex powder can increase its strength, but also to improve the hardness of a very big help. It has a very prominent waterproof performance, good bonding strength, but also can increase the elasticity of mortar and have a longer open time, and give the mortar excellent alkali resistance, can improve the adhesion of mortar/adhesion, flexural strength, wear resistance and construction, in the flexible crack resistant mortar has a strong flexibility.
 
The role of redispersible latex powder in putty powder: strong adhesion and mechanical properties, outstanding water resistance, permeability, and excellent alkali resistance, abrasion resistance, and can improve water retention, increase open time, enhance durability
1, for the role of fresh mortar
1) Improve the construction.
2) Additional water retention is added to improve cement hydration.
3) Increase workability.
4) Avoid early cracking.
2. For the role of hardened mortar
1) reduce the elastic modulus of mortar, increase the matching of the base.
2) Increase flexibility and crack resistance.
3) improve the resistance to powder off.
4) Hydrophobic or reduced water absorption.
5) to increase the adhesion of the base.
 
The redispersible latex powder meets water to form polymer emulsion, and the emulsion is dehydrated again during the mixing and drying process. The composite system formation process of latex powder in putty powder is completed by cement hydration and latex powder film formation in four steps:
When the re-dispersible latex powder in the putty powder evenly stirred with water, dispersed into fine polymer particles;
② The cement gel is gradually formed by the initial hydration of cement, the liquid phase is saturated by Ca(OH)2 formed during the hydration process, and the polymer particles formed by latex powder are deposited on the surface of the cement gel/unhydrated cement particle mixture;
③ With the further hydration of cement, the moisture in the capillary pores decreases, and the polymer particles are gradually confined in the capillary pores, forming a tightly packed layer on the surface of the cement gel/unhydrated cement particle mixture and filler;
In the hydration reaction, absorption and surface evaporation, the water is further reduced, the accumulation layer has been formed into a film, the hydration reaction products bonded together to form a complete network structure. The composite system formed by cement hydration and latex powder film formation improves the dynamic cracking resistance of putty.
 
From the practical application of the situation, as the outer wall insulation and paint transition layer of putty, its strength should not be higher than the plaster mortar, otherwise easy to produce cracking. In the whole insulation system, the flexibility of the putty should be higher than the flexibility of the substrate. In this way, the putty can better adapt to the deformation of the substrate and the deformation of the buffer itself under the action of external environmental factors, alleviate the stress concentration, and reduce the possibility of coating cracking and peeling.
 

Key words:

Redispersible latex powder