The role of wet adhesion of epoxy floor paint film

The epoxy floor paint primer that plays a shielding role should have excellent wet adhesion, and this floor paint primer should thoroughly penetrate into the fine gaps on the floor surface. Improving the wet adhesion of floor paint film can be focused on the following aspects.

① Before painting, the floor surface must be cleaned to remove any oil stains and salt. The surface of the floor is best treated to generate a phosphate film, followed by electrophoretic primer coating. The floor paint film exhibits excellent wet adhesion.     

② Require good integrity of the floor paint film, otherwise corrosion will start from the defect of the floor paint film. The viscosity of floor paint should be as low as possible, and slow volatilization and slow cross-linking coatings should be used to ensure that the floor paint stays in the liquid state for a sufficient period of time and completely penetrates the micropores on the surface of the workpiece. If possible, try to use baked primer.    

③ Wet adhesion requires the floor paint coating to not only strongly adhere to the surface of the workpiece, but also not be hydrolyzed and adsorbed when water penetrates the paint film. Baking floor paint primer usually has better corrosion resistance because at higher temperatures, resin molecules have more opportunities to orient on the surface of steel. Amino groups can promote wet adhesion and are not easily displaced by water on steel surfaces. Phosphoric acid vinegar base can also promote wet adhesion, and phosphoric acid vinegar of epoxy resin can improve the adhesion of floor paint film.   

④ The resin has good saponification resistance. Because oxygen corrosion generates hydroxide ions OH - at the cathode, the pH can even reach 14, catalyzing hydrolysis (saponification) of functional groups such as hydroxyl groups, reducing the wet adhesion of the paint film. Phthalamide groups have better hydrolysis (saponification) resistance than vinegar groups. Epoxy resin has good wet adhesion and saponification resistance. Epoxy resin primer exhibits greater saponification resistance than alkyd primer. Epoxy monoamine and epoxy/phenolic primer have good corrosion resistance, but epoxy/phenolic primer requires high-temperature curing.     

⑤ Residual water-soluble components should be avoided in the paint film of floor paint, otherwise it may cause foaming of the floor paint film. If there are hydrophilic solvents in the residual solvents of the floor paint film, these solvents are immiscible with the dry paint film of the floor paint and remain as separated phases, resulting in foaming of the floor paint film. Zinc oxide should not be present in the primer. Zinc oxide reacts with water and carbon dioxide to produce slightly water-soluble zinc hydroxide and zinc carbonate, which can cause blistering of the floor paint film. Passivation pigments such as zinc chromium yellow cannot work unless they are slightly soluble in water, so their presence in floor paint films can cause blistering.