Polyvinyl Acetal

Polyvinyl Acetal

 

an acetal of polyvinyl alcohol; a polymer of the general formula (I).

Polyvinyl acetate is hydrolyzed to form polyvinyl alcohol. An aldehyde is then added to obtain polyvinyl acetal. Thus, in addition to the acetal groups (x), polyvinyl acetals contain hydroxyl groups (y) and acetyl groups(z):

Polyvinyl acetals are hard, amorphous, and colorless substances that are soluble in aromatic hydrocarbons and in mixtures of aromatic hydrocarbons with alcohols. The hydroxyl groups of polyvinyl acetals react with acids, isocyanates, and epoxides; these reactions improve the heat resistance of items made from polyvinyl acetals and make them resistant to organic solvents and water. Polyvinyl acetals are highly adhesive to various materials, including metal and glass, and are good electrical insulators.

The most widely used polyvinyl acetals are polyvinyl formal (R = H) and polyvinyl butyral (R = C3H7). Polyvinyl formal is used mainly in the manufacture of electrical insulating varnishes (brand VL-941) and adhesives for the bonding of metals, fiberglass laminates, and wood and rubber. Polyvinyl butyral is used as a plastic film (brands PP, PSh-1, and PSh-2) and in the production of shatterproof triplex glass used in automobile and airplane construction. Polyvinyl butyral is also used in alcohol solutions in the production of butvar-phenolic adhesives (brands KA and KB) and varnishes (brands LA and LB). Anticorrosive and decorative coatings on metal items are obtained from polyvinyl butyral (brand NK) by flame spraying.

Outside the USSR, polyvinyl acetals are known by various trade names. Polyvinyl butyrals include Butvar (Canada, USA, and Great Britain), Mowital B (Federal Republic of Germany), Revyl B and Rhovinal B (France), and S-lec B (Japan). Polyvinyl formais include Formvar (USA), Formadur, Mowital F and Pioloform F (Federal Republic of Germany), and Revyl F and Rhovinal F (France).

REFERENCES

See references under .

M. E. ROZENBERG

polyvinyl acetal

A vinyl plastic produced from the condensation of polyvinyl alcohol with an aldehyde. There are three main groups: polyvinyl acetal, polyvinyl butyral, and polyvinyl formal; used in lacquers and adhesives. Polyvinyl acetal resins are thermoplastics which can be processed by casting, extruding, molding, and coating.
References in periodicals archive ?
There is a project to produce formaldehyde and its derivatives, aiming at 70,000 tonnes per year from formaldehyde and its derivatives that include urea formaldehyde, polyvinyl acetal, phenol-formaldehyde and melamine-formaldehyde.
Sekisui Chemical Co., Ltd., Osaka, Japan, has obtained a patent for a method to suppress the occurrence of coloring and foul odor of a polyvinyl acetal resin synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde without using an antioxidant.
[7] investigated the urea and ammonium sulfate treatment with an anti-caking agent consisting of an aqueous solution of a substantially water-insoluble polymer of poly vinyl acetate and polyvinyl acetals.