Polyvinyl butyral
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| Names | |
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| Other names
Poly(vinyl butyral)
Poly[(2-propyl-1,3-dioxane-4,6-diyl)methylene] |
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| Identifiers | |
63148-65-2 
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| Properties | |
| (C8H14O2)n | |
| Molar mass | Variable |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Polyvinyl butyral (or PVB) is a resin mostly used for applications that require strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility. It is prepared from polyvinyl alcohol by reaction with butyraldehyde. The major application is laminated safety glass for automobile windshields. Tradenames for PVB-films include KBPVB,Saflex, GlasNovations, Butacite, WINLITE, S-Lec, Trosifol and EVERLAM.
Laminated glass, commonly used in the automotive and architectural fields, comprises a protective interlayer, usually polyvinyl butyral, bonded between two panels of glass. The bonding process takes place under heat and pressure. When laminated under these conditions, the PVB interlayer becomes optically clear and binds the two panes of glass together. Once sealed together, the glass "sandwich" (i.e., laminate) behaves as a single unit and looks like normal glass. The polymer interlayer of PVB is tough and ductile, so brittle cracks will not pass from one side of the laminate to the other.
PVB interlayer can be purchased in colored sheets, such as for the blue or green "shade band" at the top edge of many automobile windshields. PVB interlayers can also be purchased in different colors for architectural laminated glass manufacture ranging from Bronze, Gray, Green, Brown, White and many more. Discovered in the late 1990's it was found that PVB degraded over time within laminated windows.
PVB has gained acceptance among manufacturers of photovoltaic thin film solar modules. The photovoltaic circuit is formed on a sheet of glass using thin film deposition and patterning techniques. PVB and a second sheet of glass (called back glass) are then placed directly on the circuit. The lamination of this sandwich encapsulates the circuit, protecting it from the environment. Current is extracted from the module at a sealed terminal box that is attached to the circuit through a hole in the back glass. Another common laminant used in the solar industry is ethylene-vinyl acetate (EVA).
PVB resins (provided by the manufacturer in powdered or granulated form) are also utilized in a range of applications including technical ceramic (temporary) binders, inks, dye transfer ribbon inks, paints & coatings (including wash primers), binders for reflective sheet and binders for magnetic media. PVB resin is particularly useful at bonding to metals, ceramics and other inorganics.
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