During the drying process of the coating, the drying temperature is too high or the drying time is too long, resulting in loss of light, discoloration, brittleness, cracking and peeling.

Reason:

(1) The drying equipment is out of control, causing the drying temperature to be too high.

(2) The drying time is too long. For example, in the production line, the coated object stays in the drying room overnight, especially in the case of drying above 120 ℃, it is easy to cause over-drying phenomenon.

(3) Improper selection of coating matching and drying specifications.

Prevention:

(1) Ensure that the technical condition of the drying equipment is in good condition, and prevent the drying temperature from running out of control.

(2) The drying time should comply with the process regulations. If the coated object stays in the drying room for too long for some reason, because of emergency cooling, the coated object should not be placed in the drying room overnight in high temperature drying situations.

(3) The coating and cover should be suitable, and the drying temperature of the topcoat layer should not be higher than the drying temperature of the primer layer.