Process for preparation of s-triazine prepolymers

Claim 1

Process for the preparation of s-triazine prepolymers which comprises a. condensing a hydroxy compound which has 2 or more alcoholic hydroxyl groups corresponding to the formula HO--A--(OH).sub.z (I) in which A denotes an aliphatic, cycloaliphatic or aromatic radical and z denotes an integer which is smaller by at least the number 1 than the number of carbon atoms of the radical A which are capable of substitution with more than 1/3 mol of cyanuric chloride per hydroxyl group at a temperature in the range of 0° to 250° C.; b. condensing the resulting condensation product with an aromatic hydroxy compound selected from the group consisting of compounds corresponding to the formulae ##STR8## in which R denotes hydrogen, halogen, alkyl or phenyl, and it is not necessary for several radicals R to be identical, or two radicals R which are substituents on adjacent carbon atoms can also form, conjointly with these, a carbocyclic or heterocyclic 5-membered or 6-membered ring, a represents one of the numbers 1, 2, or 3 and b represents 5-a and ##STR9## in which X represents oxygen, the sulfonyl group (SO 2 ), the carbonyl group (CO), a CH 2 chain with up to 6 carbon atoms which is optionally substituted by lower alkyl radicals, phenyl, a cycloaliphatic or aromatic 5-membered or 6-membered ring or a single bond and R 1 has the meaning indicated above for R or represents the grouping ##STR10## in which X and R have the abovementioned meaning, e represents one of the numbers 1, 2, or 3, f represents 5-e, c represents 5-d, d denotes one of the numbers 1, 2, or 3 in such a way that more than 1 hydroxyl group equivalent of the aromatic hydroxy compound is used per unconverted chlorine atom of the condensation product obtained from (a) at a temperature in the range of 0° to 250° C.; and c. thereafter reacting the free hydroxyl groups of the condensation product obtained from (b) with cyanogen halide and in the presence of a base selectd from the group consisting of alkali metal hydroxide, alkali metal carbonate, alcoholate and tertiary amine in amounts which correspond to a molar ratio of phenolic hydroxyl groups to cyanogen halide to base in the range of 1:1:1 to a slight excess of cyanogen halide at a temperature in the range of -40° to +65° C.