Polarity of paint film and painted surface

2019-08-06

From the viewpoints of molecular structure, molecular polarity and molecular interaction force, the adhesion of the paint film results from the polar group orientation of the polymer molecules in the coating, and its polar group with the polar molecules on the surface of the coated object. The mutual attraction between each other.Only when the polar phase of the two is adapted to obtain a good adhesion film; on the contrary, a good polarity coating is applied to a non-polar plate, or a non-polar coating is applied to a polar plate. A paint film with good adhesion will not be obtained.
A reduction in the polar basis of either the paint film or the coated surface will result in a decrease in paint adhesion:
1.There is dirt, grease, dust, etc. on the surface of the substrate, which reduces the polarity of the surface of the substrate and causes a decrease in adhesion.
2.A reduction in the polarity of the paint film also reduces adhesion. For example, when the amino alkyd paint is dried into a film. The -OH of the alkyd resin is further cross-linked with -CH2OH in the amino resin and is continuously consumed, resulting in a continuous decrease in the adhesion polarity point, which is an important reason for the decrease in adhesion of the aminoalkyd paint after drying.The reduction of the polar spots in the paint film may be caused by the cross-linking reaction between different components in the paint, or by the self-bonding of polar groups in the polymer molecules.

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