Oligomeric cyanoguanidines

An oligomeric cyanoguanidine of formula I ##STR13## wherein R is a divalent C.sub.2 -C.sub.20 aliphatic hydrocarbyl, mono- or polynuclear C.sub.5 -C.sub.20 cycloaliphatic, C.sub.6 -C.sub.20 aromatic radical;

• or
• R is a divalent radical of furan, pyran, pyridine, pyrrole, imidazole or thiophene;
• or
• R is a group of formula II ##STR14## wherein T is methylene, isopropylidene, CO, O, S or SO.sub.2 ;
• R.sup.1 and R.sup.2 are each independently of the other C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.10 cycloalkyl, C.sub.6 -C.sub.10 aryl, C.sub.7 -C.sub.2 aralkyl or a monovalent radical of furan, pyran, pyridine, pyrrole, imidazole or thiophene;
• and,
• n is an integer from 1 to 20,
• which radicals R, R.sup.1 and R.sup.2 are unsubstituted or are substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, nitro, halogen, R.sup.3 OCO or R.sup.3 COO, where R.sup.3 is phenyl or C.sub.1 -C.sub.4 alkyl,
• with the proviso that 1,6-hexane-bis(3-cyano-2-isobutylguanidine) is excluded.