Previously, the article discussed the packaging and printing methods of aluminum plated films, as well as the principles of ink selection and bonding composite. But this does not mean that only white ink with a high content of resin binder can have sufficient composite adhesion strength. Other factors that affect the adhesion strength of white ink include surface active dispersants and anti sinking, friction resistant wax materials in the ink system, as well as static electricity in the ink itself. The Suzhou circuit board sample manufacturer tells you that once the adhesive is applied to the surface of a white ink film containing surface active dispersants or anti sinking, friction resistant wax additives, the repulsive or almost tensile wax will cause the adhesive layer on the surface of the substrate to form a uniform point like substance, resulting in low-quality packaging printed products with poor composite fastness or low composite strength.

Secondly, due to the use of packaging printing inks with lower softening points, when aluminum plating or lamination is carried out in high-temperature environments, the ink is easily pulled over by adhesives with higher softening points or too good solubility (solubility), resulting in peeling failure.

Thirdly, due to the high content of film-forming hard resin in the surface printing ink system (such as nitrocellulose auxiliary resin in the polyamide ink system), the ink film adhesive for packaging printing ink often loses a certain degree of flexibility, resulting in good adhesion in areas with thin ink films and poor adhesion in areas with thick ink films.

Fourthly, the poor adhesion between ink and glue is also caused by excessive solvent residue in the ink or glue system. The poor adhesion between ink and substrate is caused by low surface tension of the substrate, unbalanced solvent evaporation gradient in the ink system, or low ink viscosity (low resin content).

As for the lack of adhesion between the adhesive coating and the composite bottom film after printing, it is caused by the substrate not being properly treated or the difference in the ammonia key value between the adhesive and the substrate being too large.