Polyvinyl Butyral (PVB) resign is a clear, colorless, amorphous thermoplastic obtained by condensation reaction of polyvinyl alcohol and butyraldehyde that works as a high-strength adhesive when placed between two panes of glass. When used in impact windows, the PVB resin layer is between .09 to .1 inches thick. A thicker resin layer typically results in a more expensive window but it will offer additional protection.
Laminated hurricane impact glass is manufactured using PVB (polyvinyl butyral) resin glue film between two or more sheets of glass and heating, pressing and bonding them together. This laminating process creates a strong impact and shatter resistant glass. The impact resistance of laminated glass is multiple times stronger than ordinary glass.
It is still possible to crack laminated impact glass but even if the glass breaks, the adhesion of PVB glue film keeps the fragments stuck to the PVB glue film, preventing broken glass fragments and keeping the overall integrity of the window solid.
The PVB (polyvinyl butyral) resin glue film in the middle is able to resist repeated impacts by hammers, saws and baseball bats. Some impact glass that is laminated with Polyvinyl Butyral can even stop the penetration of bullets.
The Polyvinyl Butyral (PVB) interlayer film helps reduce noise and filters Ultraviolet (UV) light and saves energy by blocking heat from the sun.
Polyvinyl Butyral (PVB) glass is safe even when broken as the integrity of the glass remains strong and glass debris and small sharp fragments keep binding with the glue PVB film in the middle.
The properties of PVB 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.
How Do Manufactures Use Polyvinyl Butyral in High Impact Hurricane Resistant Windows?
Manufacturers use high heat and pressure to fuse the PVB between two layers of glass. The laminated glass is then run through rollers to get rid of any air bubbles. Then, it’s heated and pressurized in an oil bath and allowed to cool.
After completion, impact windows are tested and given specific ratings based on performance. The Design Pressure (DP) rating identifies the load a product is rated to withstand and tells you how strong a window is. Design Pressure (DP) is expressed in pounds per square foot. In the state of Florida, the required DP for windows ranges from DP 35 (in more centralized areas) to DP 60 (for coastal areas). If you are installing impact windows yourself, you need to contact your local building department to make sure you are using the correct Design Pressure rating or your new impact windows will not pass building code requirements. We recommend using a professional impact window installer to make sure that the correct screws, bolts and adhesives are used to make sure the impact windows will hold up in a hurricane.