how to ensure the smoothness of the film while electrostatic painting
What factors will affect the smoothness of the coating
The powder coating electrostatic spray coating thickness of the thicker, the surface tends to the more formation.
The powder paint coating formation, the main factor is the particle size distribution of the scattered state of the melt viscosity, paint and curing agent.
Generally, the melt viscosity resins to obtain smooth coating of the coating thickness of 40μm, the maximum particle size of the powder size is about 60μm.
The coating thickness distribution of factors and measures
In the electrostatic painting, uneven film thickness due to the inhomogeneity of spray powder is about 2 times the solvent coating to correctly grasp the effective spray pattern of coating equipment, control a good spray indirect time to prevent uneven spray.
Was painted area is greater than of the spray pattern of coating equipment, reciprocating spray gun structure is more appropriate.
When arranged in parallel long stroke, the central parts of the painted coating is thin, short stroke with tandem arrangement, the central parts of the film to be coated thick.
What factors will affect the transfer efficiency?
The main factors affect the powder coating transfer efficiency painting equipment to paint charged powder particle size distribution, temperature and humidity of the coating environment. To this end, the powder coating range is 10 ~ 80μm.
Particle diameter and painted the efficiency of the relationship as follows:
The transfer efficiency of the particle diameter: particle diameter (μm) 150 100 35.0,150 35 to 60; transfer efficiency (%) 100 74 60 ~ 70,74 ~ 20 70 ~ 90.
Therefore: relative to the weight of the particles, static electricity with the reduction of the particle diameter increases, particles as small as 36 ~ 100μm, 150 to 400 the purpose of powders can be completely attached to the cold state to be painted, larger 74 177μmc, 80 ~~ 200 mesh) particles after spraying, the powder may be coated to fall.
Epoxy resin particle size 20 to 100μm, the balance of the particle diameter distribution standard rope should be 10-80μm, the smallest lower bound is below 10μm within 10% of particles below 60μm below 60% should be a 20 ~ 50μm sharp particle size distribution, flying high, 20μm below the micro-powder is easy to paint loss.
Coating of the particles causes and solutions
Causes for entering into the gel, the insoluble particles and impurities caused by the powder coating.
- fine particles in the powder coating easy accumulation of parts to change the airflow direction in the gun head or pipe coating equipment emitted agglutination state accumulation to some degree attached to the painted above, baking is not will melt and become a diameter of 0.5-3mm degree of particles attached to the spray chamber wall and recycling equipment, plastic compounds;
- due to pigment in the manufacture of the powder coating process condensate;
- some of the resin curing reaction of gel particles in the melt blending process, these particles will form a coating on the particle
- electrostatic spray, environmental dust problems should arouse enough attention.Dust from the air, flaking material on the fiber and baking equipment operator on the work of plastic bag recycling equipment such as dust in the process of electrostatic powder coating can also cause pollution and bring the particles.