EVA (Ethylene Vinyl Acetate) film and PVB (Polyvinyl Butyral) film are two different polymer materials that can be used for glass laminated structures. The PVB has been the reference material for the glass lamination on building construction and transportation industries for many years. EVA is challenging PVB as a lamination material because of its superior properties.
When it comes to laminated of PDLC film, meaning Liquid Crystal based smart film, then PVB interlayer is not suggested as PVB is damaging the PDLC film. The PVB "attacks" the PDLC film, doesn't matter the process you use to melt it: press or vacuum.
In light of the above, EVA is the interlayer of choice for us.
There are many EVA types, each melt in a different temperature and it is very important to verify that your EVA melting temperature is same as your smart film melting temperature. Our EVA is customized for smart film lamination purpose.
What if I need to make a PVB lamination?
Lamination of smart film with PVB involved both pressure and heating.
You have to seal well all 4 sides of the smart film before the lamination (see picture). This adds much complexity to the process. This is why most of the customers are using EVA.