Requirements for the use of coating dispersants

2021-09-24   Pageview:282

1. Good dispersion performance to prevent mutual aggregation of filler particles;
2. It has proper compatibility with resins and fillers, and has good thermal stability;
3. It has good fluidity during forming and does not cause color drift;
4. Does not affect the performance of the product, is non-toxic and inexpensive;
5. The amount of dispersant is generally 5% of the mass of the masterbatch.

 

 

 

 

 

 

 

 

 

 

 

Water-based coatings are mainly used as wetting and dispersing agents with anionic and non-ionic polysoap compounds.

Anionic polysoap compounds are mostly acrylic copolymers, copolymers of maleic anhydride, vinyl ether and olefins.
Non-ionic polymer surfactants are mostly polyoxyethylene compounds. For example,  clariant pe wax 520 nonionic compounds obtained by esterification of fatty acids and ethylene oxide are the most commonly used wetting and dispersing agents for water-based coatings.

In water-based latex paint, anionic low-soap compounds, such as sodium polyacrylate, are mainly used, together with non-ionic wetting agent fatty acid ethoxy derivatives. This type of poly soap is different from ordinary wetting and dispersing agents. They have polar groups and can be firmly adsorbed on the surface of pigment particles. Large molecular chains can form a thicker adsorption layer, which constitutes steric hindrance. effect. At the same time, the hydrophilic group can also be ionized, so that the pigment particles are charged with a counter-charge to form an electric double layer, and the pigment particles are also protected by the charge repulsion. In the polysoap dispersion system, the electrolyte will not have much influence on the dispersion stability, because the electrolyte can only affect the stable charge system, but not the polymer stable system.

The stable dispersion system of ordinary low molecular weight wetting and dispersing agents is only protected by charge repulsion, so it is very susceptible to the influence of electrolytes.

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