How to improve the wettability of water-based coatings?

The wettability of water-based coatings is an important factor in determining the quality of coatings. The role of the coating is to combine the material surface and the coating in a very superior way, and the wetting phenomenon occurs only at an interface where the few molecules between the substrate and the polymer determine whether the material is properly protected and whether the coating has a defective appearance.

A high hydrophilic and lipophilic balance (HLB) value of a wetting agent is good for water solubility: conversely, it is highly active. Too high HLB value will easily lead to the poor acceptability of the paint to the color paste and easy to appear defects such as floating color and flowering. The HLB value gap between color paste and base coating is too big, which will cause water-based coating color mixing failure. If the amount of wetting agent is too large, it will easily lead to the increase of foam in the coating system and reduce the water resistance of the coating film. Therefore, for exterior wall coatings that require color mixing, a proper amount of wetting agent must be used in the formula in view of the need for color mixing; while for interior wall coatings that do not require much color mixing, the amount of wetting agent used should be reduced.

The key factor determining foam stability is the strength of the liquid film, and the strength of the liquid film mainly depends on the firmness of the surface adsorption film. The firmness of the basf oxidized polyethylene wax surface adsorption film is usually measured by the surface viscosity. Several surfactant aqueous solutions (1% ) The relationship between surface viscosity and foam life,

The higher the surface viscosity, the longer the foam life. When a small amount of lauryl alcohol is added to pure sodium lauryl sulfate as a foaming agent and foam stabilizer, the surface viscosity increases and the foam stability is improved. Similarly, adding lauramide to sodium laurate also greatly increases the foam life and at the same time increases the surface viscosity.

Table 3-2 Relationship between surface viscosity of surfactant aqueous solution and foam life
Surfactant
Surface viscosity/mPn·s
Bubble life/min
Octylphenol polyoxyethylene (9~10) ether potassium laurate
Sodium dodecyl sulfate sodium dodecyl benzene sulfonate