The flexibility of the paint film is the performance that the paint film will not break after being bent to a certain extent, so it is also called the bendability of the paint film. If the paint film is not damaged after the specified bending, it means that the product has good flexibility.
To measure flexibility, the painted tinplate plate is bent on a shaft with a certain diameter, and it is expressed by the diameter of the smallest shaft that does not cause damage to the paint film after bending. There are six kinds of shaft diameters: 1, 2, 5, 10, 15, and 20 mm. The smaller the diameter of the bend, the greater the elongation of the outer surface of the paint strand, so the flexibility through a diameter of 1 mm is good, and the diameter of 20 mm is the worst. Generally, the flexibility of the coating is required to be 1-3 mm.
When the paint film is bent on the shaft, the paint film will elongate. Use a four-fold magnifying glass to observe whether there are changes such as graining, texture and peeling. If there is no abnormality, it is qualified.
Putty flexibility is measured, the coating is thicker, and the test principle is also a kind of bending test, and the diameters of the bending rods are 100 and 50 mm respectively.
