Process for preparing cross-linkable binders for coating made of fluoropolymer solutions

摘要

A process is described for the preparation of a crosslinkable paint binder by working up a solution of a fluorine-containing copolymer composed of copolymerized units of a perfluoroolefin, a vinyl ester of a short-chain, saponifiable carboxylic acid and a vinyl ester of a strongly branched carboxylic acid which resists saponification. In this process, the bulk of the solvent and the residual monomers are first removed by distillation, the residual highly viscous copolymer is then dissolved in a mixture of alkanol and another solvent which is also capable of dissolving the saponified copolymer to form a homogeneous solution, and the alkaline saponification is subsequently carried out. If desired, the solvent is removed and exchanged for a paint solvent and this solution is finally filtered. A mild saponification is achieved in this manner.