Problems and countermeasures in film coating technology:
Adhesive sheet: mainly due to the too fast spray volume, which violates the principle of solvent evaporation balance and causes the sheets to stick to each other. In this case, the spray volume of the coating liquid should be appropriately reduced, the hot air temperature should be increased, and the rotation speed of the coating machine coating pan should be accelerated.
The "orange peel" film appeared: mainly due to improper drying, the spray pressure of the coating liquid was low, and the sprayed droplets were unevenly heated and the film was corrugated. In this case, the evaporation rate should be controlled immediately to increase the spray pressure.
"Bridge": refers to the film on the engraving film to cause the logo to be blurred. The solution is to slow down the spray speed of the coating and reduce the drying temperature, and at the same time, control the hot air temperature.
Spotting: This condition is caused by uneven mixing with the coating liquid or insufficient fineness of the solid traits. The solution is to mix well with the coating liquid.
Cracks, cracks, flaking or edge wear of the tablets on the surface or edge of the tablet: if the solid content of the coating liquid is improperly selected, the speed of the coating machine is too fast, and the spray volume is too small, the appropriate coating liquid solid content should be selected. , properly adjust the speed and the amount of spray; if the core hardness is too bad, you should improve the formulation and process of the core.
The film "blooming" appears: this situation is caused by excessive humidity of the hot air, too long spray range, and poor atomization effect. At this time, the temperature should be appropriately lowered, the spray range should be shortened, and the atomization effect should be improved.
There is color difference between the tablets: this situation is caused by uneven fan-out of the spray or excessive solid content of the coating liquid or slow rotation speed of the coating machine. At this time, the angle of the spray gun should be adjusted, the solid content of the coating liquid should be lowered, and the rotation speed of the coating machine should be appropriately increased.
There are pinholes on the surface of the film: this is caused by the entrapment of excess air when preparing the coating solution. Therefore, avoid excessive air entrapment during dosing.