Discussion on orange peel in powder electrostatic spraying

Orange peel is a common and difficult to overcome Leveling Problem in the coating process There are many influencing factors, which greatly affect the smoothness of the coating Orange peel like surface can be said to have a greater impact on the appearance of decorative products Orange peel is an urgent problem for powder coating manufacturers The appearance of orange peel in powder coating is closely related to the characteristics of powder coating, i.e leveling performance, the influence of equipment in coating production and the control of process parameters in coating process 1 The causes and solutions of orange peel problems 1.1 the influence of the characteristics of powder coating on orange peel problems 1.1.1 the influence of resin molecular weight in powder coating 1.1 the selection of resin molecular weight in powder coating synthesis is more important Although the high molecular weight resin has good weather resistance, the phenomenon of orange peel is caused by the fact that the powder in the molten state has a large viscosity and is difficult to flow From the perspective of viscosity, the selection of low molecular weight resin is conducive to improving the leveling performance of powder coating, but the weatherability of low molecular weight resin is poor, which requires the powder coating manufacturer to comprehensively consider the selection of synthetic raw materials [1] 1.1.2 the influence of particle size distribution generally speaking, when the proportion of powder with particle size larger than 75 μ m is too large, the leveling performance of the coating film will be poor, and orange peel phenomenon will easily occur At the same time, the spraying area per unit of powder is reduced, and the electrostatic effect of powder coating becomes worse in the process of construction, which is easy to cause powder removal When the proportion of powder whose particle size is less than 10 μ m is large, the dry powder fluidity of powder coating is slightly poor at this time, which will cause the spraying construction problems such as no powder spraying and gun sticking [2] 1.1.3 influence of leveling agent leveling agent is an important additive in the production of powder coating When the manufacturer produces powder coating, leveling agent is added to improve the leveling performance and even coating performance of powder coating, improve the flatness of coating film and reduce orange peel 1.1.4 influence of powder stability the stability of powder coating indicates the phenomenon of cross-linking reaction of molecules under the storage condition of powder coating; the more intense the cross-linking reaction of powder, the larger the molecular weight of powder, reflecting the increase of viscosity and poor leveling characteristics of powder under the curing temperature, and the orange peel is easy to appear.