Analysis of bubbles in protective film

- May 17, 2018 -

Commun problems:


(1) the absorption or exclusion of the ink to the glue.

(2) thin film wettability is poor.

(3) poor wetting caused by low temperature

(4) coating roller stopper, damaged box foreign body adhesion, resulting in insufficient glue or too much glue on the part.

(5) the viscosity of the glue is too high or too low during coating.

(6) the temperature of the drying box is too high and the glue is bubbling.

(7) a bubble caused by CO2. It is generally due to the influence of moisture and isocyanates.

(8) the residual solvent is too high, and the solvent permeability is poor. The bubbles are sandwiched between two layers of film.

Countermeasures:

(1) select the appropriate ink and increase the amount of coating. For dry composite white ink selection is particularly important, its impact is manifold.

(2) enhance the wettability of the film to the film, improve the defects of local adhesive, improve the coating amount, improve the temperature and pressure of the composite roll, use the smooth roller, reduce the mixing speed and increase the time of wetting and sizing, select the good wetting glue and preheat.

(3) preheating the glue and film and increasing the temperature of the compound roller.

(4) cleaning the coating roller, strengthening the coating amount and coating roller management.

(5) adjust the viscosity. Changing coating roll

(6) adjust the drying conditions.

(7) increase the coating temperature and pressure of the compound roller, increase the hardness of the roller and increase the rubber hardness of the roller to 80-85 degrees. And adjust the angle of the "wrap angle" of the film before pressing the roll, and enter the compound roller as far as tangent direction is concerned.

(8) to take moistureproof measures, such as avoiding the moisture absorbing materials such as nylon and corylate PORPHYRAS, to absorb the CO2 from the NCO base after moisture absorption, and keep the environment dry and the curing agent sealing material.

(9) drying conditions should be controlled properly, low boiling point solvent should be used, and the curing temperature should be raised appropriately.


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