POLY(VINYL BUTYRAL)

Uses

Ceramic binder, dry toners, wood coatings, composite fiber binders, structural adhesives and interlayer in safety glass.

Preparation

Poly(vinyl butyral) may be prepared by dissolving poly(vinyl alcohol) (PVA) in a mixture of water and methanol and adding butyraldehyde and a small amount of sulfuric acid as a condensation agent and heating to 60°-70°C. The best quality poly(vinyl butyral) is stabilized by slurrying in alkali in order to prevent viscosity changes and discolorization. Urea is also used to stabilize the pH to about 1.5.
Some processes involve saponifying poly(vinyl acetate) (PVAc) to PVA with aqueous hydrochloric acid; butyraldehyde is then added directly. The resulting poly(vinyl butyral) solution is neutralized and the product precipitated with water, washed, and dried.