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Polyvinyl butyral (PVB) is a specialty resin used primarily as a raw material
for laminated safety glass sheet for automotive and architectural applications.
It is produced by a few companies that also usually produce sheet.
Polyvinyl butyral was first produced commercially in 1938 and is the most
important member of the polyvinyl acetal family of resins. Several grades of
PVB resins are in commercial use, differing in the molecular weight of the
polyvinyl alcohol used in their manufacture and in the degree of coverage of
the backbone hydroxyls by butyraldehyde. The polyvinyl alcohol used in the
manufacture of PVB for laminated safety glass contains only small amounts (1–3%)
of residual acetate groups from the precursor polyvinyl acetate (PVAc). In
PVB sheet resin, typically about 18–23% (by weight) of the alcohol groups
in the polyvinyl alcohol raw material remain unreacted. The remaining hydroxyl
groups have been reacted with n-butyraldehyde to form acetal linkages. Film
is made, usually by the resin producers, by adding plasticizers and other additives
to the resin. Functionalities (alcohol, ester and acetal content) as well as
plasticizer and moisture levels of the formulation are important properties
of PVB safety glass.
The following pie chart shows world consumption of polyvinyl butyral:
Sales in the primary end markets for polyvinyl butyral depend on the performance
of the general economy especially for safety glass in automotive and architectural
markets. The PVB resin and PVB film and sheet industry will expand into China
as the quality of its PVB resin improves; this will help supply the expanding
automotive production (at the expense of imported PVB film and sheet).
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