Urea based compounds may be of the following formula: ##STR19## Wherein R1 and R2 may be the same or different, each of which may represent a hydrogen, a C1 -C6 alkyl, a methylol (--CH2 OH) and methoxymethyl (CH3 OCH2 --) or C2 -C6 alkoxymethyl (n-butoxy methyl: CH3 CH2 CH2 CH2 OCH2 -- for example) with the proviso that either R1 or R2 is a methylol (--CH2 OH), a methoxymethyl (CH3 OCH2 --) or a h