Polyvinyl butyral (or PVB) is a resin made from the reaction of polyvinyl alcohol with butyraldehyde in the lab. The main area of application is laminated safety glass for the automotive industry. Windshield. Trade names for PVB films include KB PVB, Saflex, GlasNovations, Butacite, WIN LITE, SLec, Trosifol and EVERLAM.
Properties
Annealed, thermosetting or hardened glass can be used to produce laminated glass. While laminated glass breaks if hit hard enough, the resulting glass fragments tend to adhere to the interlayer instead of falling free and causing injury.
In practice, the intermediate layer gives laminated glass panes three advantageous properties: first, the intermediate layer serves to distribute impact forces over a larger area of the glass panes and thus increase the impact resistance of glass. Second, the interlayer works to bond the resulting fragments together when the glass eventually breaks.
Third, the viscoelastic intermediate layer undergoes plastic deformation during impact and under static loads after impact, absorbs energy and reduces the penetration of the impacting object, as well as reducing the impact energy transmitted to the impacting object, e.g. a passenger in a car accident. Therefore, the benefits of laminated glass include security and protection. Laminated glass also has decorative uses. The middle layer can be coloured or stamped.
Applications
PVB is used for laminating things because of its clarity. The glueing process takes place under heat and pressure. When laminating under these conditions, the PVB intermediate layer becomes optically transparent and connects the two panes of glass with one another. After sealing, the “sandwich” (i.e. laminated glass) behaves like a unit and looks like normal glass. The PVB polymer interlayer is strong and ductile so that brittle cracks do not spread from one side of the laminate to the other.
The PVB intermediate layer can be covered in coloured foils, for example for the blue or green “shadow band” on the upper edge of many car windows.PVB interlayers can also be purchased in various colours for making laminated glass for architecture, from bronze, grey, green, brown, white and many more. It was discovered in the late 1990s that PVB in laminated windows degrades over time.
PVB has established itself among the manufacturers of thin-film photovoltaic solar modules. The photovoltaic circuit is formed on a sheet of PVB using patterning techniques.
Next, the PVB and the second pane of glass (the so-called backglass) are placed directly on the circuit. The lamination of this sandwich encapsulates the circuit and protects it from environmental influences. The module is supplied with power in a sealed terminal box, which is connected to the circuit through a hole in the rear glass. Another common laminate used in the solar industry is ethylene-vinyl acetate (EVA).
PVB resins (supplied by the manufacturer in powder or granular form) are also used in a variety of applications including engineering (temporary) ceramic binders, inks, ink transfer ribbon paints, paints, reflective sheets binders, and magnetic products binders. PVB resin is particularly useful for bonding nets.