The mixture of anionic and nonionic surfactants is esse […]
The mixture of anionic and nonionic surfactants is essentially a very effective emulsifier for water insoluble monomers, and changing the ratio of the two can better control the viscosity of the emulsion. When an anionic or nonionic mixed emulsifier is used, the concentration of the emulsifier increases, the latex particles become smaller, the particle size distribution becomes wider, the viscosity of the emulsion increases, and when the total amount of the emulsifier is constant, the emulsifier and the monomer at the initial stage of the polymer reaction The ester molar ratio (E/M) is the determining factor affecting the viscosity of the emulsion. The larger the initial E/M, the larger the number of primary particles formed, and the smaller the particle size of the emulsion, the greater the viscosity.
In addition, in the anionic and nonionic mixed emulsion systems, the type and amount of the emulsifier affect the emulsion particle size and its distribution and the viscosity of the emulsion, and also affect the minimum film forming temperature of the emulsion. Because the viscosity increases as the particle size of the emulsion becomes smaller, the capillary pressure and the total surface area of the emulsion film formation are increased, which facilitates the mutual penetration of the ion surface chain ends and promotes ion-forming film formation.
Although ordinary surfactants can give polymer latex tape a stable effect and play an important role in emulsion polymerization, in the application of the final film formation of latex, it will bring some adverse effects to the product, such as reducing the polymer. Water resistance and chemical resistance. In order to overcome the adverse effects of common emulsifiers in latex products, while retaining some excellent properties of emulsion polymerization and products, an effective method is to change the emulsifier.