Why Bubble Appeared during the lamination process?

The cause of bubble formation:

Different types of composite substrates have different physical properties (such as gas permeability), and have a great relationship with the formation of composite film bubbles. Generally speaking, a substrate with good gas permeability (such as BOPP, CPP, CPE, LDPE) or a composite substrate with poor gas permeability (such as PVDC, BOPA) and another composite substrate with good gas permeability are compounded. It is not easy to generate bubbles. [ roll to roll lamination machine]

However, if the two substrates have poor gas permeability, when they are compounded, bubbles are easily generated, such as PVDC and BOPA. This is because the gas permeability of the two composite substrates is relatively poor, and the adhesive inevitably mixes a small amount of air on the compounding system. At the same time, the isocyanate adhesive itself is cross-linked and solidified during the curing stage of the composite film, and also produces gaseous by-products such as carbon dioxide (CO2). In this way, a large number of tiny bubbles are generated, thereby affecting the apparent quality of the composite film. [ film lamination machine]

At the same time, in order to make the composite substrate have a certain surface tension, the surface properties of the substrate must be treated, such as corona treatment, to improve the wettability of the surface of the composite substrate and improve the roughness, but the roughness exceeds At certain limits, it is difficult to be filled with viscous glue. Thus, large and small bubbles are formed between these minute engaging faces.