The impact resistance of the coating film can be measured according to the method in the national standard "Determination of Impact Resistance of Paint Films" (GB/T1732-93). This standard stipulates the test method for the impact resistance of the paint film to be expressed by the maximum height (cm) of the heavy hammer falling on the test panel without causing damage to the paint film.
This standard applies to the determination of the impact resistance of sub-paint films .
(1) Instruments and equipment
①4x magnifying glass.
② Impact Tester (also called impact Tester) as shown in Figure 6-l7.
③ Metal rings and metal sheets for calibrating the impact Tester.
④ Calibration of the puncher Tester Unscrew the slider, put a 3mm thick metal piece on the upper end of the punch, place a piece of metal sheet with a thickness of 1mm±0.5mm on the surface of the fast anvil, and use an object with a smooth bottom to remove it from the punch. The upper part of the punch goes on, adjust the screw amplitude so that the upper end of the punch is level with the metal ring, and the steel ball at the lower end just touches the metal sheet, so the depth of the punch entering the anvil is 2mm ± 0 . lmm.
The surface of the steel ball needs to be clean and smooth. If it is not smooth or smooth, the steel ball should be replaced.
⑤Materials and dimensions, unless otherwise specified or agreed, the test plate is an iron plate, which shall meet the technical requirements of GB/T9271, and the size is 50mrnx120mmx0.3mm; the thin steel plate shall meet the technical requirements of GB 708, and the size is 65mmxl50mmX(0 .45~0. 55)mm (for testing the impact resistance of putty).
(2) Test steps
① Unless otherwise specified, the test shall be carried out under the conditions of 23°C±3°C and relative humidity of 5o%±1±5%.
② Put the paint film of the painted sample upwards on the iron stone. The impacted part of the test plate is not less than 15mm away from the edge, and the distance between the edges of each impact point shall not be less than 15mm. The heavy hammer is fixed at a certain height of the slide by the control device (the height is specified or agreed by the product standard), and the control button is pressed, and the heavy hammer falls freely on the punch. Lift the weight and take out the test panel.
Record the height at which the weight falls on the test plate.
Three impact tests were carried out on the same test panel. Observe with a magnifying glass of 4 times to judge whether there are cracks, wrinkles and peeling off of the paint film.
