The corona treatment to TPU film, will enhance the surface tension to be 52-56 dyne/cm. The surface tension of TPU film after corona treatment is related to the pressure from electrode and the distance between the corona roller. The back corona will be caused if there is air between the TPU film and corona roller.
The will be consequence of TPU film back corona as below:
1. The ink printing will be anti-sticky.
2. The aluminum will be transferred after aluminum plating.
The best solution to avoid back corona of TPU film is to adjust the pressure of the dandy roller in front of the corona roller. The pressure of two side of dandy roller should keep the same and appropriate. Moreover, the corona roller and dandy roller should pass strict dynamic and motionless balance tests.