Talking about the Technical Requirements of Electrostatic Painting of Powder Coatings

1、 The influence of coating environment temperature and temperature on the thickness of coating film is 170-200g / min of powder spraying, 70kv of voltage and 20cm of distance between spray gun and coating When the temperature is 20-30 ℃ and the humidity is 60-80%, the coating efficiency of the powder coating is better, and the coating film is thicker 2、 In the powder coating, the thicker the film is, the smoother the surface will be The main factors that affect the smoothness of powder coating film are the size and distribution, melting viscosity, dispersion of pigment and curing agent, etc For the resin with high melting viscosity, the maximum particle size of the powder is about 60 μ m if the smooth film with 40 μ m film thickness is to be obtained 3 The thickness of the coating film is distributed in the electrostatic powder coating Due to the nonuniformity of the sprayed powder, the nonuniformity of the coating film thickness is about twice that of the solvent coating It is necessary to correctly master the effective spray pattern of the coating equipment, control the indirect time of spraying, and prevent the nonuniformity of spraying When the area of the coated object is larger than the spray pattern of the coating equipment, the reciprocating powder gun structure is more suitable When the long stroke is arranged in parallel, the coating film in the center of the coated object is thinner, while the short stroke in series is used, and the coating film in the center of the coated object is thicker 4、 The main factors that influence the coating efficiency of powder coating are the charging mode of coating equipment, particle size distribution of powder, temperature and humidity of coating environment, etc Therefore, the suitable powder coating range is 10-80 μ M The relationship between coating efficiency and particle size the relationship between particle size and coating efficiency is as follows: coating efficiency of particle size: 35.0 for particle size (μ m) above 150, 35-60 for 150-100 The coating efficiency (%) is 60-70 for 100-74 and 70-90 for 74-20 Therefore, relative to the weight of particles, the electrostatic force increases with the decrease of particle diameter, the particle size is 36-100 μ m, 150-400 mesh powder can completely adhere to the cold coating, and the larger 74-177 μ MC, 80-200 mesh) particles may fall from the coating after spraying The particle size of epoxy resin is 20-100 μ m, the standard rope of equilibrium particle size distribution should be 10-80 μ m, the minimum limit is 10% below 10 μ m, 60% below 60 μ m, and it should be 20-50 μ m sharp particle size distribution Because the powder under 20 μ m is easy to fly, the coating loss is also more 5、 The reason for the particles of the coating is that the powder coating is mixed with gelatinization, insoluble particles and impurities The fine particles in the powder coating are easy to accumulate in the head of the spray gun or the part in the pipe which changes the air flow direction after the coating equipment When they accumulate to a certain extent, they will be sprayed out in the agglutination state Attached to the coating, it will not melt when baking and become 0.5-3 mm diameter particles attached to the wall of the powder spraying room and in the recycling equipment In the process of manufacturing powder coating, the pigment will produce agglomerates In the process of melting and mixing, some resins will undergo curing reaction to produce gelatinized particles, which will form particles on the coating film In electrostatic spraying construction, the problem of environmental dust should also be paid enough attention The dust comes from the air, the fiber on the recovery equipment of the operating adhesive bag and the peeling off on the baking equipment, etc These dust will also cause the pollution of the coating film and bring particles during the electrostatic powder spraying process.