How to measure film Adhesion?

When the paint is applied to the surface of the object to be coated, the ability of the paint film to be firmly combined with the bottom layer is called adhesion. Adhesion is one of the important properties to evaluate the paint film, which can be measured by adhesion Tester. If the adhesion of a paint is not good, it is impossible to talk about the problem of good performance such as mechanical strength.

There are generally two types of test methods for the determination of adhesion. One is a comprehensive measurement method, such as the cross-cut method, cross-cut method and circle method; the other is a peel test method, such as the open method and the pull method. Examples are as follows:

(1) cross-cut method

Apply the sample on the sample (usually galvanized iron sheet), after drying, cut six parallel cuts on the paint film ( The length is about 1o~2o mm, and the distance between the cut marks is 1 mm), which should cut through the entire paint film; then use the same method to cut six lines, perpendicular to the former, to form many small squares, and then touch it lightly with your fingers. The paint film should not fall off from the grid, but still combined with the surface of the bottom plate is qualified, calculated by 100%.

(2) circle method

my country's national standard adopts the circle method. This method uses an adhesion Tester, uses a phonograph needle as the needle, and fixes the model (the base material of the model is still galvanized iron sheet) on a movable test bench. When the handle is turned, the needle point makes a uniform circular motion on the paint film, and depicts the lines of overlapping circular rolling lines. The adhesion of the paint film can be determined by observing the peeling position of the paint film from the texture of the circular rolling line. There are seven levels of adhesion in the circle drawing method, the first level is better, the second level is slightly worse, and the rest are analogous, and the seventh level is the worst.