| 摘要 |
<p>The invention concerns a colouring agent which contains water and one or a plurality of water-soluble dyes with anionic groups which have a pKa value which is essentially not above A, combined with the precursor of a first auxiliary substance, the first auxiliary substance as such having the pKa value C and C being greater or smaller than A or equal to A. The invention further concerns a printing or writing process using a colouring agent of this type.</p> |
