The yellowing phenomenon of container epoxy interior paint has very little effect on the performance of the paint film itself. After a little polishing of the yellowed inner paint film, it can be found that the yellowing only occurs in a thin layer on the surface, and the paint film under the yellowing layer is consistent with the originally designed color, and the physical and chemical properties of it are tested. Also fully meet the design requirements. Yellowing of the interior paint has a noticeable negative impact on appearance. Because most of the interior paint of the container is light gray RAL7035, after passing through the drying tunnel heated by natural gas, the surface of the paint film becomes yellow and dark, and the old state is obvious. Another problem is that the off-line boxes need to be repaired on the stockyard. Although the same kind of paint is used, the paint on the stockyard is naturally dried, and the paint film is not affected by natural gas. It is a normal light gray color, and the color difference between the two is very obvious on the same box, which will indeed leave a bad impression on the viewer, thus questioning the quality of the paint product.
Paint companies generally adopt the instrument measurement control method to control the color of products, that is, before each batch of products leaves the factory, they must use a color measuring instrument to control the L, a, and b values. If the color difference between the test results and the standard Color Chart is within If it is within the required range, the product is allowed to be shipped, otherwise it needs to be re-colored. In view of the yellowing problem of the interior paint of the container, the color control standard of the interior paint formula was reset, referring to the RAL7035 standard RAL Color Chart, within the allowable range of color difference, the control index of the L value was increased, and the control index of the b value was reduced , the lightness of the product has been improved, and the tendency of the yellow phase has been reduced. In this way, even if it is slightly affected by the natural gas medium, the yellowing of the inner paint is not very obvious.
For more details, please refer to the full text of "Analysis and Improvement of the Yellowing of the Container Interior Paint" (Li Jie, Liu Lin, Tao Xin, Han Min)
