The inspection of the physical and mechanical properties of the paint film can be divided into the inspection of gloss, color and appearance, flexibility, impact resistance, adhesion, hardness and other items.
(1) Determination of gloss
It can be measured according to GB1743-79 "Determination of Paint Film Gloss". The GZ-2 photoelectric gloss meter with a fixed backlight is used for the measurement, and the percentage (%) of the ratio of the regular reflection light from the surface of the standard sample is expressed. The larger the ratio (%), the better the gloss, otherwise vice versa .
(2) Determination of color and appearance
It can be determined according to GB1729-79 "Determination of Paint Film Color and Appearance". It refers to the evaluation result by comparing the color and appearance of the paint film with the standard color plate and standard sample. If the sample is close to the standard color plate, it is qualified (testing instrument: Color Chart)
(3) Determination of flexibility
Measured according to GB1731-79, "Determination of Flexibility of Paint Films". That is to say, it is expressed by the diameter of the smallest shaft that causes damage to the paint film by bending the surface of the sample on shafts of different diameters. Measuring method: After the paint film is hard-dried, under constant temperature and constant temperature conditions, with the paint film (sample) facing up, use both hands to press the paint sample on the shaft rod with a diameter specified in the product standard, bend it around the rod, and after bending, use the thumbs of both hands to respond Weigh on the center line of the shaft rod, and the bending action is completed within 2 to 3 seconds. Afterwards, observe the paint film model with a four-fold magnifying glass. If there are damage phenomena such as texture, cracking and peeling, it is unqualified.
(4) Determination of impact resistance
Measured according to GB1732-79 "Determination of Impact Resistance of Paint Film". The measurement result is expressed as the product (kg.cm) of the weight of the hammer of the paint film impactor and the maximum height that falls on the sample plate without causing damage to the paint film. If the measurement result is 50kg.cm is better, 40kg.cm is worse. Its determination should be checked according to the technical indicators specified by the product to determine whether it is qualified.
(5) Determination of adhesion
GB1720-79, "Determination of Paint Film Adhesion". The measurement results are evaluated by the paint film adhesion Tester (892-1 type) according to the completeness of the paint film within the scratch range of the circular rolling line, and expressed in grades. The evaluation grades are divided into 1, 2/3/4/5/6/7), and the 1st grade is better.
(6) Determination of hardness
Determination of GB1730-79, "Determination of Hardness of Paint Film". The measuring instrument can use a pendulum Hardness Tester (QFZ-II: type paint film pendulum Hardness Tester), which is placed on the painted film with a certain weight, and the swing decay time (S) in the specified amplitude is the same as that in the glass. It can be expressed by the ratio of the time of swing decay in the same amplitude on the plate 90MMx120MMX (1.2~2.0)mm. The larger the ratio, the higher the hardness.
(7) Determination of wear resistance
The determination of the abrasion resistance of the paint film shall be determined according to GB1768-79 "Determination of the Abrasion Resistance of Paint Films". That is to say, it is expressed by the weight loss of the paint film (g) after the specified number of abrasions with a paint film abrasion Tester under a certain load. More weight loss, poor wear resistance; less weight loss, good wear resistance.
(8) Determination of flexibility of putty film
It can be measured according to GB1748-79 "Putty Film Flexibility Determination Method". Bend the sample during the test, and observe whether the film cracks or falls off, which is represented by the minimum diameter of the bending arc. If there is no crack on the surface of the putty film, it is qualified.
