In the powder coating, coating curing bad reasons have two aspects, one is the formula design of powder coating is not reasonable, coating performance can not meet the requirements, the second is the performance of powder coating itself is no problem, but in the powder coating, coating process control is not reasonable, resulting in coating performance failed to reach technical indicators.

From the perspective of powder spraying, if the match between resin and curing agent is not reasonable in the formulation design, such as the selection of resin reactivity or the selection of curing agent varieties and dosage is not reasonable; Packing mass percentage or volume concentration is too large these problems will affect the physical and mechanical properties of the film.

From the perspective of powder coating process, there are several reasons that affect the curing of coating materials.

(1) the baking temperature of the baking oven fails to reach the baking temperature required by  spraying powder. While baking furnace temperature control can meet the design temperature or when no load required by the powder coating baking temperature, but the full load cases, caused by a lack of the total quantity of heat, sometimes can not meet the design temperature or powder coating the baking temperature, the temperature is low, particularly the northern region winter workshop if baking furnace heat preservation condition is poor, be before coating in baking furnace and lower temperature, by coating material thickness and thermal capacity is big, it is easier to appear this kind of problem. This problem is more likely to occur when the temperature of the baking oven cannot reach the curing temperature of the powder coating. When the temperature of baking oven cannot reach the curing temperature of powder coating, on the one hand, it can be solved by increasing the heating power; On the other hand, it can be solved by extending curing time and other measures.

(2) in the baking oven, the baking curing time cannot reach the baking time required by the powder coating. In the baking condition of powder coating, baking time refers to the baking time calculated after the coating reaches the baking temperature, rather than the time calculated after the coating is put into the baking oven. The thicker the coating material, the more hanging pieces, then the heat capacity of the coating is also greater, the coating temperature to control the temperature of the time it takes longer. In a certain length of baking oven, the effective baking time is shorter when the velocity of conveyor chain is constant. If the effective baking time is not enough, coating curing is not complete, coating physical and mechanical properties can not meet the requirements. Therefore, in the powder coating, it is best to use the furnace temperature tracking instrument to determine the temperature change of the coated material in the baking oven under full load condition, in order to determine a reasonable baking curing temperature and time, so as to ensure the complete curing of the coating film, but also to ensure the physical and mechanical properties of the coating film.

Posted by: hannahgwendolyn at 09:39 AM | No Comments | Add Comment
Post contains 524 words, total size 6 kb.