How to ensure the smoothness of coating film by electrostatic painting of powder coating?

The development of electrostatic coating equipment industry can not be separated from the echo of all kinds of equipment. Today we introduce a trick.

1. What factors affect the smoothness of the coating?

When the powder coating is electrostatic sprayed, the thicker the coating is, the more smooth the surface is.

The main factors affecting the smoothness of powder coatings are particle size and its distribution, melt viscosity, dispersion of pigments and curing agents, etc..

Generally speaking, for the resin with high melting viscosity, if you want to obtain 40 m film thickness of the smooth coating, then the powder size is the largest, the particle size is about 60 M.

Two, influence coating thickness distribution factor and solution measure

In the electrostatic powder coating, due to non-uniform spray powder so that the uneven degree of film thickness is about 2 times of solvent coating, to correctly grasp the effective spray pattern, coating equipment control spraying indirect time inhomogeneity, prevent spraying.

When the coating area is larger than the spray pattern of the coating equipment, the structure of the reciprocating duster gun is more suitable.

When arranged in parallel long stroke, the coating of the central part of the coating is thinner, arranged in series short stroke, and the coating in the central part of the coating is thicker.

Three, what factors will affect the efficiency of painting?

The main factors affecting the efficiency of powder coating are coating equipment's electrification mode, powder particle size distribution, temperature and humidity of coating environment, etc.. To this end, the range of suitable powder coatings is 10~80 M.

The relation between particle diameter and coating efficiency is approximately as follows:

Particle diameter coating efficiency: particle diameter (m) is over 150, 35 and 150~100 is 35~60; coating efficiency (%) 100~74 is 60~70, 74~20 is 70~90.

The relative to the weight of the particle, static electricity with decreasing particle diameter increases, particles as small as 36 ~ 100 m, 150 ~ 400 mesh powder can be fully attached cold coated, the larger of the 74 ~ 177 MC, 80 ~ 200 mesh) particles after the injection, powder may be from coated drop.

Epoxy resin particle size 20 ~ 100 mu m, the balance of the particle size distribution should be 10-80 m standard cable, the lower limit of the fine is less than 10 m to less than 10%, less than 60 m particle is less than 60%, should be 20 ~ 50 m sharp size distribution, due to less than 20 m powder coating is easy to fly, the loss is more.

Four, film coating particles causes and Solutions

The reasons for causing into powder coating gel, insoluble particles and other impurities.

1) fine particles of powder coatings in the easy accumulation of changing the direction of flow in the spray head after coating equipment or pipe parts, when the accumulation to a certain extent to the aggregated state spray attached to the object to be coated, does not melt when baking into 0.5-3mm diameter degree of particles, gel in the spraying chamber wall attachment and recycling equipment in;

2) in the manufacture of powder coatings, the pigment produces agglomerates;

3) in the melt mixing process is part of the resin curing reaction to produce gel particles, these particles will form a coating on the particles.

4) environmental dust should be paid enough attention in electrostatic spraying. Dust comes from the air, the work of the operator, the fabric on the bag, the fiber on the recycling device, and the flaking on the baking equipment. These dusts also cause fouling and particles on the coating during the electrostatic dusting process.