PV adhesive in dry compound contains a large amount of ethyl acetate. Ethyl acetate is an excellent solvent for printing ink binders. When PV glue is applied to the reverse printing ink, ethyl acetate in the glue penetrates into the ink. After ethyl acetate enters the printing surface of BOPP, the already bonded part between the printing ink and BOPP is loosened and even delaminated; while ethyl acetate with PV glue penetrates the ink layer, the whole printing is improved. The adhesion fastness of the layer to the PV glue results in the fact that the original printing ink with good adhesion is separated from the BOPP film.
The solution is to apply PV adhesive on the vacuum aluminum plating surface of VMALCPP film. After being dried at 60-90°C, it is compounded with the reverse printed VBOPP film. In this way, when the reverse printing ink is in contact with PU adhesive, PU adhesive is used. After drying in the drying tunnel, most of the ethyl acetate content has evaporated, and no penetration of ethyl acetate into the reverse printing ink layer will occur, affecting the adhesion of the ink layer to BOPP. At the same time, increase the solid content of PU glue (reducing the amount of ethyl acetate solvent), increase the temperature of the drying tunnel, and increase the time of staying in the drying tunnel (slowing the composite speed) can improve and prevent this delamination phenomenon.