(b) Quaternary ammonium compounds having the formula ##STR2## wherein R3 is a C16 -C20 acyclic, aliphatic hydrocarbon group, R4 and R5 are selected from the group consisting of R3 and C1 -C3 alkyl groups, R6 is a C1 -C3 alkyl group or a benzyl group, and A is an anion imparting water dispersability.