| 摘要 |
The use of whitening pigments comprising (a) a melamine-formaldehyde or phen ol- formaldehyde polycondensation product and (b) a water-soluble fluorescent whitening agent of formula (1), wherein R1 and R2 are each independently of the other -OH, -Cl, -NH2, -O-C1-C4alkyl, -O-aryl, -NH-C1-C4alkyl, -N(C1- C4alkyl)2, -N(C1-C4alkyl)(C1-C4hydroxyalkyl), -N(C1-C4hydroxyalkyl)2 or -NH- aryl, for example anilino, aniline-mono- or -di-sulfonic acid or an anilinesulfon-amide, morpholino, S-C1-C4alkyl(aryl), or a radical of an amin o acid, for example aspartic acid or iminoacetic acid, which radical is substituted at the amino group, and M is hydrogen; sodium; potassium; calciu m; magnesium; ammonium; mono-, di-, tri- or tetra-C1-C4alkylammonium; mono-, di - or tri-C1-C4hydroxyalkylammonium; or ammonium di- or tri-substituted by a mixture of C1-C4alkyl and C1-C4hydroxyalkyl groups, for whitening paper coating compositions.
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