The flexibility of the coating film can be measured according to the method in the national standard "Determination of Paint Film Flexibility" (GB/T1731-93). This standard specifies the method for measuring the flexibility of paint film using a flexibility Tester, and expresses the flexibility of the paint film by the smallest shaft diameter that does not cause damage to the paint film.
(1) Materials and instruments
① Bottom plate The bottom plate should be flat and free from distortion, and there should be no visible cracks and wrinkles on the board surface. Unless otherwise specified, the bottom plate shall be a tin plate of 120mm><25mm><(0.2~0.3)mm.
②4x magnifying glass.
③ The flexibility Tester is shown in Figure 6-14. The flexibility Tester consists of seven steel shafts with different diameters (1mm, 2mm, 3mm, 4mm, 5mm, 10mm, 15mm in diameter) fixed on the base of.
(2) Operation steps
① Unless otherwise specified, the test should be carried out under the conditions of individual temperature and humidity specified in GB/T9278.
② Use both hands to turn the paint film of the test panel upwards, press it tightly on the shaft rod with a specified diameter, and use the force of two thumbs to bend the test board around the shaft rod within 2 to 3 seconds. After bending, the two thumbs should be symmetrical to Shaft centerline.
③ After bending, use a 4x magnifying glass to observe the paint film. Check whether the paint film is damaged by texture, cracks and peeling.
