Polyvinyl formal
Polyvinyl formal is a polyvinyl acetal plastic from the group of thermoplastics .
Manufacturing
Polyvinyl formal is produced from polyvinyl alcohol by acetalization with formaldehyde with elimination of water , whereby the degree of acetalization can vary. In the polymer excerpt shown below, the degree of acetalization is 75% (75% of the hydroxyl groups in polyvinyl alcohol are converted into acetal groups, 25% are left over):
To a small extent, acetal formation can also take place between two polyvinyl alcohol chains, so that crosslinking occurs.
use
Polyvinyl formal is used for wire insulation and as a paint component for petrol cans. With a degree of acetalization of 95%, polyvinyl formal has a high tensile strength in the dry state. Polyvinyl formal is used as an additive for phenolic resin adhesive for the production of multilayer light metal plates, which are used in systems subject to vibration (aircraft construction).
Individual evidence
- ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 1123.
- ^ A b Karlheinz Biederbick: Kunststoffe , Vogel-Verlag, 4th edition, 1977, pp. 110–111, ISBN 3-8023-0010-6 .