Adhesion of film Appearance performance test

1. What is adhesion

Adhesion refers to the sum of the physical and chemical binding force of the coating film on the surface of the substrate. The wettability of the coating on the substrate and the roughness of the substrate surface also affect its adhesion when painting. The test methods are divided into direct method and indirect method. , The direct method is mainly the pull-off method (GB5210-85), which measures the pulling force required to peel the paint film from the surface of the substrate. Indirect methods such as scratch hardness, impact strength, flexibility, etc. all show the adhesion of the coating film, but the circle method and cross-cut method are generally used to test the adhesion of the coating film, such as the cross-cut paint film adhesion Tester, The operation is quick and convenient.

2. Test method of paint film adhesion

Circle method (GB/T1720-39)

The circle-marking method is to use a circle-marking adhesion Tester, apply a load until the needle can penetrate the coating film, draw a circular rolling line (length 7.5cm±0.5cm) evenly, and mark 1-7 respectively according to Figure 8-9 For the part where the paint film is marked, more than 70% of the grid is considered to be intact, and the smallest grid part where the paint film is intact is the corresponding adhesion grade. Grade 1 is better, and Grade 7 is the worst.

Cross grid method (GB/T9286--88)

The cross-cutting method uses a high-alloy steel cross-cutting knife (also known as an adhesion Tester) with vertical and horizontal cross cutting to detect a grid of 1 mm. The rating method for the number of cuts is 6. See Table 8-5. The better is (Gt0 grade, the worst is Grade Gt5, Ogilvy & Mather’s ranking is 5 is the best, 0 is the worst. When the number of cuts is 11, it is expressed as a percentage of intact grids. After cutting, it should be separated with adhesive tape, and additional instructions should be given.