Introduction to the polymerization reaction process of acrylic emulsion.

Acrylic emulsion polymers are often used in fields such as coating printing, electrostatic flocking, fabric lamination, warp sizing and coating processing. So, what is the polymerization reaction process of this emulsion? Let's take a look together with the editor!

1. Latex particle generation stage: In a water dispersion system where emulsifiers and a small amount of monomers are present, the number of micelles in the acrylic emulsion is much greater than the number of monomer droplets. Therefore, water-soluble initiators initiate polymerization reactions in the aqueous phase. When the concentration of monomers in water is low, the monomer free radicals formed will also enter the solubilizer bundles to grow. The solubilizer bundles then become the latex particles of monomers and polymers. At the end of this stage, The micelles vanished and all formed latex particles.

2. Uniform polymerization stage: At this stage, the number of latex particles that have been generated remains unchanged, and the concentration of monomers within the latex particles is also constant. The termination of the initiator in the particles is dominant, while the termination in the aqueous phase can be disregarded. The desorption rate of free radicals is extremely small and can be ignored compared to the adsorption rate. This stage starts from the end of the first stage until the monomer droplets disappear. It is an extremely important stage in the aggregation process.

3. Deceleration stage: In the initial stage, the concentration of latex particle monomers decreases very slowly, while the volume of latex particles not only does not decrease but also increases with the increase of conversion rate. When the monomers dissolved in the aqueous phase are exhausted, the concentration of the monomers in the latex particles gradually decreases as the conversion rate increases. As the conversion rate increases, the concentration of monomers in the latex particles begins to decline rapidly. At the same time, because the polymer is denser than the monomers, the volume of the latex particles will slightly contract as the conversion rate increases. At this stage, the concentration of monomers in the latex particles continuously decreases. Due to the increase in viscosity and the slowdown in termination rate, an automatic acceleration phenomenon will occur. As the conversion rate increases, the concentration of the polymer within the latex particles grows larger and larger. The macromolecular chains entangle with each other, resulting in an increasing viscosity within the latex particles and a greater resistance to the diffusion of free radical chains. A gelation effect occurs, which leads to an increase in the polymerization reaction rate, an increase in molecular weight, and a wider molecular weight distribution.

That's all for the polymerization reaction process of acrylic emulsion that the editor has introduced to you. Due to the differences in raw materials and ratios used, the performance of this emulsion varies, and as a result, its applications are also different.