Poor mechanical properties of powder coatings include: poor adhesion, poor flexibility, poor impact strength, poor hardness and other items.
(1) The main reason for the poor mechanical properties of powder coatings is that the curing time or temperature of the powder is not enough. Under certain conditions, the curing time of the powder is inversely proportional to the curing temperature. At present, the powder curing conditions we can know are: epoxy powder coating, epoxy-polyester powder coating, which can be cured at 140 ℃ for 25 minutes, It can also be cured at 220 °C for 5 min. Each powder coating product has its own curing conditions. The result of arbitrarily shortening (extending) the curing time or lowering (raising) the curing temperature is that the powder coating cannot be fully cured or over-baked, which will inevitably affect the powder coating. The adhesion, impact strength and other properties of the layer will ultimately damage the image of the product in the minds of customers.
(2) The powder coatings provided by powder manufacturers have quality problems, most of which are problems with components such as curing agents, resins, fillers, and pigments.
(3) For the poor adhesion, another reason is that the pretreatment of the parts is not clean, and the presence of oil, dust and other substances on the surface affects the adhesion of the powder.
(4) The storage time of the powder coating exceeds the storage period, thus affecting the mechanical properties of the powder coating.
(5) In addition, a meticulous, dense and complete phosphating film is a prerequisite for ensuring the powder has good mechanical properties after curing. This reason should also be considered when investigating the reasons for the poor mechanical properties of the powder.
(6) If the powder solidification time is too long or the temperature is too high, the flexibility of the powder will also be reduced.
