In order to improve the redispersibility of redispersible polymer powder and prevent caking during drying and storage, protective colloids or surfactants (emulsifiers) should be added before drying, making the redispersible polymer powder with strong hydrophilicity and alkali sensitivity. The most commonly used protective colloid is partially hydrolyzed polyvinyl alcohol (PVA). PVA contains a lot of hydroxyl groups, with quite poor water resistance. And the vinyl acetate polymer itself is poor in the water resistance, especially hot water resistance, due to its polar ester and carboxyl groups. In the redispersible polymer powder containing PVA and carboxyl groups, polyvalent metal salts can be added to improve its water resistance, especially hot water resistance, since PVA and carboxyl groups can react with metal salts to become insoluble in water. In the emulsion containing PVA, aldehydes can also be added for PVA acetalization and then to reduce its water absorption. In addition to PVA, some other protective colloids with good water resistance can also be selected to ensure the water resistance of product, such as polyacrylic acids and modified polyacrylic acids.
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