. . . "A process according to claim 12, wherein a compound of the formula (1) is further added for the kneading, P--[X--Y--Z--N(R1)R2 ]n ( 1) wherein P is an organic dyestuff residue, a heterocyclic ring residue or an aromatic polycyclic compound residue, X is a divalent binding group composed of a chemically rational combination of 2 to 15 atoms selected from S, C, N, O and H, Y is a" .