The invention relates to an aqueous coating composition comprising a compound having reactive groups A, and a quaternary ammonium compound according to Formula I, II or III wherein R1 is an alkyl, alkenyl, alkylaryl or arylalkyl group having from 5 to 50 carbon atoms; R2 is a C1-C100 hydrocarbyl group, optionally containing heteroatoms; R3 and R4 are alkylene groups having from 1 to 4 carbon atoms; R5 and R6 are H or C1-C100 hydrocarbyl group, optionally containing heteroatoms; R7 is a C1-C100 hydrocarbyl group, optionally containing heteroatoms; R8 is a C1-C100 hydrocarbyl group, optionally containing heteroatoms; R9 is H or a methyl group; Z is a substituent containing at least one reactive group B which is capable of reacting with the reactive group A; X− is an anion; y is 0 or 1; a is 0 or 1; and the sum of y and a is 1 or 2 and m is an integer from 1 to 30, preferably between 1 and 10, or between 2 and 6 n is an integer from 0-30, preferably between 1 and 10, or 2 and 6 T is a monomer unit; U is a
