How to improve the water resistance of water-based coatings?

The water resistance of paint refers to the resistance of paint film to water. The water resistance of the paint film is related to the polar group contained in the resin, the water-soluble salt in the pigment, the various additives in the coating film and other factors, but also affected by the surface treatment of the coating and the drying conditions of the coating film and other factors.
, we're going to explore how to improve water resistance and water resistance in water

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can start with water-based resins, such as water-based polyurethane, water-based acrylic polymer structure, emulsion polymerization is usually used in the surfactants are two parents, that is, one end has affinity, the other end has hydrophobic.
after polymerization, these surfactants remain in the emulsion, remain in the paint film after film, hydro-water-based and water-based action, prompting water in the paint film more penetration, diffusion and migration, increasing the absorption rate. In order to overcome the adverse effects of surfactants, soap-free polymerization legal preparation emulsions are now available, and the water resistance of emulsions synthesized during emulsion polymerization has been significantly improved.
different emulsions or water dispersants have very different absorption rates of less than 10%, high can be more than 100%, mainly determined by the structure of the polymer. The hydro-hydro-water structure in polymer molecules and the hydro-hydro monomer used in synthesis have a great influence on the water absorption rate and water resistance of the paint film.
(meth) acrylic, (meth) acrylic ethyl, (meth) acrylic hydroxypropylate, Malayate, dihydroxymethyl acid, and hydroxymethylbutyric acid and other hydrophosphate hydrophosphate hydrophosphate hydrophobic monomers, can improve the dispersion of polymers in water, is conducive to the formation and stability of emulsion or water dispersion, but also brings the film after the paint film absorption rate increased, water resistance and other shortcomings.
absorption rate increases when there is a polyglycol chain segment in the polyurethane structure, while polyurethane hydro degradation with polyester structure is highly likely and water resistance is affected.
the introduction of fluorocarbon monosomes or silicone compounds in the synthesis of fluorocarbons can improve the water resistance of the paint film and increase with the increased use of fluorocarbons and silicon compounds.
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second, by adding diplomatic joints cross-linking, cross-linking can significantly improve the water resistance of paint film.
The same paint is cross-linked by the addition of diplomatic compounds, whether using isocyanate curing agent cross-linking, nitrogen propylene cross-linking, or epoxy compound cross-linking, although the absorption rate of the decline is different, but usually can be reduced to less than 15%.
hydrophobic isocyanate curing agent, the stronger the hydrophobicity of the hydrophobic chain segment, the higher the absorption rate of the paint film after cross-curing. Water-resistant emulsions or water dispersants themselves have very low water absorption rates, and the absorption rate after cross-linking decreases by a small margin. On the other hand, the water absorption rate decreased greatly after the crosslinking agent of the paint film, which is hydro-hydroelectitlic.
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In addition to the above two ways, but also through physical methods to improve the water resistance of the paint film, paint formulation to add water-repugnent compounds can improve the hydrophobic properties of the paint film, reduce or reduce the immersion of the paint film.
such as wax lotion and wax powder, can effectively increase the interface contact angle of the paint film. In addition, some hydrophobic additives have better results, which can produce results similar to the lotus leaf effect. This hydrophobic effect is due to the irregular accumulation of hydrophobic additives on the surface of the paint film, the migration of hydrophobic agent will make the lotus leaf effect disappear, the paint film added to the hydrophobic agent after multiple scrubbing effect is gradually weakened.
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