Polyvinyl Butyral Films
Properties
Polyvinyl butyral (PVB) is a clear, colorless, amorphous thermoplastic obtained by condensation reaction of polyvinyl alcohol and butyraldehyde. The resin is known for its excellent flexibility, film-forming and good adhesion properties as well as outstanding UV resistance.
The properties of PVB like its solubility in solvents and compatibility with binders and plasticizers depend on the degree of acetalisation and polymerization. An increase of the number of butyral groups in the polymer usually improves the water resistance of PVB films. PVB can also be cross-linked. Its cross-linking capacity depends on the number of residual OH groups in the polymer which can undergo condensation reactions with phenolic, epoxy, and melamine resins as well as with isocyanates.These chemical modifications produce high quality solvent resistant PVB coatings and films.
One of the major uses of PVB films is safety glass. Due to PVB's good adhesion to glass, most of the splinters of fractured glass will adhere to the surface of the PVB film and thus prevent personal injury by large and sharp glass fragments. PVB laminated glass also offers an improved sound barrier, good impact resistance, and almost 100% absorption of UV light. The later is important for the protection of interiors from fading due to UV exposure.
Manufacturers
PVB is the most popular interlayer material for safety glass. It is currently manufactured and sold by a number of companies including Du Pont (Butacite®, SentryGlas®), Eastman (Butvar®, Vanceva®), Saflex (Eastman), and Kuraray (Trosifol®).
Applications
The most important application of PVB film is laminated safety glass for automobile windshields. PVB films find also applications in the construction industry as laminated safety and security glass, as well as in the photovoltaic industry to improve the long-term durability of solar modules.
PVB is suitable for flexible packaging applications. It is
considered non-toxic and some grades have received food contact
approval (21CFR175.300).