Process for the production of polytriazines in the presence of high-boiling esters

Claim 1

A polytrimerizable mixture of 30 to 99.9% by weight of at least one aromatic cyanic acid ester of the formula ##STR7## wherein R is hydrogen, halogen, alkyl having 1 to 9 carbon atoms, phenyl, alkoxy having 1 to 4 carbon atoms or alkoxy carbonyl having 1 to 4 carbon atoms in the alkyl moiety, or two R substituents together on adjacent carbon atoms of the phenyl moiety to which they are attached together form a hydrocarbon ring containing from 5 to 6 carbon atoms or together form with O, S or N a 5 or 6-membered heterocyclic ring; R' has the same meaning as R or is the group ##STR8## A is a bond, alkylene having 1 to 9 carbon atoms or said alkylene substituted by phenyl or alkyl having 1 to 4 carbon atoms, a divalent cycloaliphatic or aromatic 5 or 6-membered ring or said divalent ring including oxygen as a hetero atom, oxygen, -SO 2 -, ##STR9## a is 0 to 5 when e is 1 and 2,5 when e is 1; b is 5 - a when e is 1 and 6 - a - d when e is 0; c is 5 - d; d is 0 to 5; and e is 0 to 3 with the proviso that the sum of a + d is always from 2 to 5. or a partially cross-linked prepolymer of said cyanic ester of said formula which is soluble in organic solvents and 0.1 to 70% by weight of at least one high boiling ester plasticizer having a boiling point above 250° C at 760 Torr.