DE-INKING PROCESS

摘要

A process for the de-inking of printed waste paper containing paper that is printed with ink containing hydrophilic binder resins (for example as in the flexographic process) comprising a) pulping the waste paper at a pH of 4 to 7 in the presence of an ink collector chemical containing a hydrophobic portion and being cationic and water-soluble or sparingly water-soluble at a pH from 4 to 7; b) applying to the resultant paper pulp a strong alkali to obtain a pH of 10-11; and c) separating the detached printing ink particles from the fibre suspension of the paper pulp by flotation. A cationic surfactant is preferably added at the same time as the ink collector chemical. The invention permits the de-inking of mixed paper printed with both hydrophilic and hydrophobic inks.