Plastic parts are more or less affected by various factors before molding, causing various problems. The plastic surface is often sprayed by plastic parts to increase decoration and prevent plastic parts from aging, impurities and other bad defects. It also improves the hardness of the surface. Like the refrigerator door. Therefore, for this type of spray paint coating, how to make the process more perfect requires strict testing of the paint film coating.
Scholar Wu Juzhen believes in the article "Refrigerator Plastic Door Spray Painting Process" that: the amount of curing agent affects the hardness of the paint film. It is believed that as the curing amount increases, the hardness of the paint film increases, which is the result of more cross-linking points. With the increase of time, the hardness also increases, indicating that the reaction of -NCO and -OH is a slow process, which is related to the reactivity of the resin and the curing agent itself. It can also be seen from Table 2 that the hardness of 1# paint does not increase much after 48 hours, indicating that the curing is complete, while the hardness of 2# paint and 3# paint is still increasing, this is because the -NCO group not only reacts with the -OH in the resin , It will also absorb and react with moisture in the air, the cross-linking point will continue to increase, and the hardness will continue to increase, but after the curing dose increases, the curing time will increase accordingly.
The following are the common problems and solutions of refrigerator door spray products
The pencil hardness test method can be used to measure the hardness of the paint film. The mainstream measuring instrument at home and abroad is the pencil Hardness Tester. for reference.
