Use of triazine-based UVAs for use as quenchers in paper-making processes

A process for the inhibition (quenching) of the effect of an anionic fluorescent whitening agent on a substrate, comprising treating the substrate with a triazine UVA compound of the formula ##STR35## in which M is hydrogen, sodium, potassium, ammonium, mono-, di-, tri- or tetra-C.sub.1 -C.sub.4 alkylammonium, mono-, di- or tri-C.sub.1 -C.sub.4 hydroxyalkylammonium or ammonium that is di- or tri-substituted by a mixture of C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.4 hydroxyalkyl groups;

• n.sub.1 and n.sub.2, independently, are 0 or 1, provided that if n, is 0, n.sub.2 is 0;
• R.sub.9 is optionally substituted aryl or a group having the formula ##STR36## in which R.sub.11 is optionally substituted alkyl or optionally substituted aryl;
• or, when n.sub.2 is 0, R.sub.9 may also be a group having one of the formulae:
• ##STR37## in which R.sub.11 is optionally substituted alkyl or optionally substituted aryl;
• ##STR38## in which R.sub.12 is M, optionally substituted alkyl or optionally substituted aryl;
• ##STR39## in which R.sub.12 has its previous significance;
• ##STR40## in which R.sub.13 is hydrogen, optionally substituted alkyl or optionally substituted aryl;
• and R.sub.10 is hydrogen, halogen, optionally substituted alkyl, optionally substituted aryl, ##STR41## --NH.sub.2, --N(CH.sub.2 CH.sub.2 OH).sub.2, --N[CH.sub.2 CH(OH)CH.sub.3 ].sub.2, --NH--R.sub.12, --N(R.sub.12).sub.2 or --OR.sub.12, in which R.sub.12 has its previous significance,
• or R.sub.10 is an aminoacid residue from which a hydrogen atom on the amino group has been removed;
• or with a triazine UVA compound of formula ##STR42##