Since PET film has excellent barrier properties and strong anti-leakage properties, it is difficult for the solvent to penetrate, and the solvent absorption of the ink is relatively poor. The binder (resin) of the plastic surface printing ink has a good affinity with the PET film, so printing on the PET film is stronger than the printing ink in the plastic composite. In fact, the ink layer transfer of the printed PET film after compounding has nothing to do with the use of surface printing ink. Instead, the use of compound inner printing ink is more prone to ink transfer.