Causes and preventive measures of the paint not drying or poor drying
Time：2019/09/25 Traffic volume：4
1. The temperature of self drying or drying does not meet the requirements. Generally speaking, the drying speed of two-component coating will be greatly reduced below 10 ℃, and the drying process of coating will be extremely slow or even stop. The time of chemical crosslinking doubled with every 10 ℃ decrease of temperature.
2. The oven reaches the set temperature after warming up, but the heating will stop without holding for a period of time.
3. One continuous spraying is too thick, resulting in abnormal solvent accumulation in the coating. Especially in the continuous spraying with ordinary coating, 2 to 3 layers can be sprayed according to the specified requirements, but in order to pursue a better appearance or leave a margin for polishing, 4 or 5 layers are sprayed, so that although the paint film is thick, the drying performance of the coating is greatly reduced, and it is difficult to meet the drying requirements within the specified time.
4. Curing agent and diluent are not used together. When using auxiliary materials such as curing agent and diluent, we must adhere to the principle of matching, and can not use different brands of auxiliary materials to replace each other. Even products of the same brand should be used according to the regulations of the manufacturer.
5. The poor ventilation or high humidity in the self drying place causes the solvent contained in the coating not to volatilize normally, and the drying speed of the coating is greatly reduced.
6. The bottom surface of the coating is not clean, leaving wax, oil, water and other substances that affect the drying. In small area repair, there are a lot of problems in drying.
7. Too much high boiling point solvent is added to the coating. In order to improve leveling or rainy days to prevent "whitening", excessive high boiling point solvents such as "cyclohexanone" were added, which volatilized very slowly and remained in the film for a long time, affecting drying.
8. Insufficient or excessive amount of curing agent. Curing agent is not dispensable in two-component coating, it is crosslinked with resin in coating according to a certain proportion to form paint film. If the curing agent is insufficient or redundant, it will cause poor drying. It must be added according to the requirements of coating regulations.
9. The diluent contains excessive water, alcohol and acid. This situation is often seen in the use of cheap alternative diluents. In particular, the use of various nitrodiluents instead of 2K diluents. Such thinners will not only contain more impurities such as water and alcohol, but also may contain substances that react with curing agents, resulting in abnormal drying of coatings.
10. Improper polishing. Especially before the paint is completely dry, that is, the solvent in the paint is not completely volatilized, polishing will be started, which will not only cause the loss of gloss on the surface of the paint film, but also cause the abnormal drying of the paint due to the solvent erosion in the wax solution.
11. The paint caused by some incorrect spraying process cannot be completely dry or fake dry. For example, in the second coating of plain paint, if 2K plain paint is used as the primer, but no curing agent is added, and then varnish is sprayed on it, the result of such operation is that the paint film is not dry.
12. Mistakes occur in the process of color matching. The typical phenomenon is that the film is soft due to insufficient resin, which is mainly caused by insufficient resin supplement in the process of fine adjustment or incorrect calculation of resin quantity in the process of adding formula. This situation is rare. In addition to the soft paint film, it is usually accompanied by low gloss, easy to scratch and fall off, and the fragments are easy to be powdered. In color mixing, if the resin is used incorrectly, for example, 2K resin is used in the second pass of plain paint, it will not dry for a long time.