Common problems and solutions in steel drum coating

1.

the reason:

1.

2.

3.

solution:

1.

2.

3.

2.

the reason:

Bleeding at the cut edge is usually due to the low surface tension of the paint sprayed first, and the high surface tension of the paint sprayed later.

solution:

Control the surface tension between the chromatic paints.

3.
The paint mist on the lid of the barrel falls and spreads

In the picture, the white paint mist spreads to the blue paint on the lid of the bucket, and the white paint mist spreads

the reason:

1.
The surface tension of white paint is lower than that of blue paint, and the mist of white paint falls on the surface of blue paint and spreads;

2.
The power of the ventilation equipment in the spray booth is low or does not work, and the paint mist stays in the spray booth and is difficult to drain away in time
.

solution:

1.
Appropriately add leveling agent to blue paint to reduce its surface tension;

2.
Check whether the air path is normal, and improve the working efficiency of the ventilation equipment;

3.
Do not face the nozzle directly to the barrel, but keep a proper angle of inclination in the direction of rotation to reduce the impact of paint mist on the barrel
.

4.
Paint mist splashing on the barrel body

In the picture, the blue paint mist splashes onto the white paint of the barrel

the reason:

1.
The direction of the blue paint nozzle is unreasonable, the caliber is too large, and the pressure is too large.

2.
The surface tension of blue paint is low, and paint mist spreads
.

solution:

1.
Adjust the position and angle of the nozzle, the angle can be adjusted slightly away from the white paint; choose a small diameter for the edge trimming nozzle, which can be 650017 or 650011;

2.
Appropriately reduce spraying air pressure;

3.
Add a proper amount of leveling agent to the white paint to reduce the surface tension of the white paint
.

5.
Paint film scorching and prickly heat

the reason:

1.
The paint mist of different nozzles overlaps, and the paint film is too thick in some parts;

2.
The surface drying speed of the paint is too fast, the opening time is short, and the moisture is too late to volatilize;

3.
The heating rate of the area before baking is too fast, and the paint film will start to crosslink before the moisture is completely volatilized, resulting in prickly heat
.

5.
Paint film scorching and prickly heat

solution:

1.
Adjust the position and layout of the nozzles, reduce the overlapping area of ​​different paint mists, and appropriately reduce the spraying time of the parts with too thick paint film;

2.
Under the premise of ensuring that the paint on the barrel body does not sag, appropriately increase the amount of slow-drying solvent added to reduce the surface drying speed and extend the opening time;

3.
The drying tunnel adopts two-stage or three-stage baking.
It is recommended that the temperature in the front zone of the drying tunnel should not exceed 100℃ for 3-5min, and the middle zone and rear zone should be set at 140-160℃, and the time is about 10min to form a uniform rise.
Temperature curve, do not heat up too fast in the front area
.

6.
Poor local adhesion, local loss of gloss, shrinkage holes

the reason:

The above-mentioned different phenomena are caused by one reason.
The bottom material of the steel drum is oily and has not been cleaned, resulting in poor adhesion or shrinkage; if the amount of oil is small, there is no shrinkage, but it will be shiny after baking.
The degree will drop
.

solution:

1.
The barrel body needs to be pre-treated, degreasing, pickling, phosphating or silane treatment
.
If there is no condition for pre-treatment, the oil on the substrate must also be wiped off before spraying to ensure that the surface of the barrel is clean; the rag should be replaced in time if it is dirty
.

7.
The paint film is blooming as a whole

the reason:

The compatibility of the main resin of the coating and the color paste is not good, resulting in floating color of the coating; at the same time, the viscosity of the coating is low, the anti-sagging performance is poor, and the undercurrent appears
.

solution:

1.
Verify the compatibility of the main resin of the formula and the color paste, and whether there is any floating or blooming phenomenon; if so, the dispersant used in the color paste should be selected; try to use the resin paste to color the color, the resin used in the resin paste and the main resin are the same Resin
.

2.
Properly increase the viscosity of the paint and improve the sag resistance of the paint
.