Verfahren zur Herstellung von Polymerisaten

摘要

Polymers having the recurring unit where R is a direct link or an organic group containing 1 to 24 carbon atoms and R1 is a cyclic organic group containing 5 to 24 carbon atoms are made by reacting a dihydrazide of formula with a dianhydride of formula Many dihydrazides and dianhydrides are specified. The reaction may be effected in an organic solvent and the polymer may be precipitated from this by adding water. The resulting polymers may then be cured (e.g. while as a coating on a surface) to produce thermoset polymers of formula The examples disclose reacting 3,4,31,41-benzophenone tetracarboxylic acid dianhydride or cyclopentane tetracarboxylic acid dianhydride with terephthalic dihydrazide, isophthalic dihydrazide, adipic dihydrazide or azelaic dihydrazide.ALSO:Articles, especially metal pipes for use in oilfields, are coated by applying to them a solution in an organic solvent of a polymer of formula:- where R is a direct link or an organic group containing 1 to 24 carbon atoms and R1 is a cyclic organic group containing 5 to 24 carbon atoms and obtainable by reacting a dihydrazide with a dianhydride. The articles are then heated to cause the polymers to thermoset to polymers of formula:- In Example 1, a solution in dimethyl formamide of a polymer obtained by reacting terephthalic dihydrazide with 3, 4, 3/sv, 4/sv-benzophenone tetracarboxylic acid dianhydride was applied to a metal pipe and the pipe then heated to 200 DEG C.