Verfahren zur Herstellung von Polybenzoxazindionen

1,173,608. Benzoxazine dione polymers. FARBENFABRIKEN BAYER A.G. 6 Dec., 1966 [3 Jan., 1966], No. 54524/66. Heading C3R. The invention comprises benzoxazine dione polymers of formula where n is from 10 to 250, R1 is an alkylene, cycloalkylene, phenylene, alkylphenylene, naphthylene or diphenylene group or a radical of formula where y is an alkylene, cyclohexylene carbonyl or sulphone group or an oxygen or sulphur atom, and R is a tetravalent group derived from benzene, naphthalene, anthracene or diphenyl or a radical of formula where x is an alkylene or cyclohexylene group and R2 is an alkyl group. The polymers are prepared by reacting a di-o-hydroxyaryl dicarboxylic acid ester of formula where R 1 is an alkyl group, cycloalkyl group or aryl group, with a diisocyanate of formula in an organic solvent at 20‹ to 200‹ C. in the presence of a tertiary amine catalyst. In examples the esters are resorcinol-4,6-dicarboxylic acid diphenyl ester, hydroquinone-2,5- dicarboxylic acid diphenyl ester, 4,41-dihydroxydiphenyl - 3,31- dicarboxylic acid diphenyl ester, 4,41 - dihydroxy - diphenylmethane - 3, 31-dicarboxylic acid diphenyl ester, 4,41-dihydroxy - 3,31 - dimethyl - diphenyl methane- 5,51-dicarboxylic acid diphenyl ester and resorcinol-2,4-dicarboxylic acid diphenyl ester, and the diisocyanates are diphenyl ether-4,41- diisocyanate, tolylene - 2,4 - diisocyanate and naphthalene-1,5-diisocyanate.