The problem of ink particle redeposition during processing of flexo-printed paper for recycling is well known. This matter has also been part of several discussions in the literature during the last years1. According to the literature survey, the problem of flexo deinking is on the one hand caused by the ink particle size and its hydrophilic nature, and on the other hand by ink particle redeposition. Both effects are interacting and are difficult to distinguish. Several authors explain that the redeposition is activated due to the highly fragmented ink particles after the introduction of mechanical force and the alkaline environment during pulping. Therefore they propose very short pulping times and neutral pH-values. The role of charge carriers in the process water in this context is mentioned but described as non-significant.
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