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Aug 12, 2010 12:00 AM
“Good recyclability is a crucial feature for the sustainability of the graphic paper loop,” states INGEDE, an association of leading European paper manufacturers founded in 1989. “Using actual offset and rotogravure paper printing processes in combination with modern recycling technology based on flotation deinking, the paper fibres can be used more than five times to produce newsprint and magazine papers.”
INGEDE states that separating the paper coming from household collections into fractions of different printing technologies like offset and rotogravure vs. flexo, dye-based inkjet and pigment-based inkjet inks to treat them separately does not seem to be a feasible option. There is one optimized recycling process for joint deinking of the printed paper mix, called flotation deinking.
INGEDE Method 11 simulates this process. According to the association, “Bleaching the deinked pulp with peroxide or dithionite is not a standard process for standard newsprint paper, but is used for pulps with higher brightness for improved paper grades. Contrary to DPDA's last press releases, the deinkability of production inkjet printed paper products still needs a lot of improvement in order to ensure sustainable recycling not only of these papers but of the whole paper mixture. DPDA claims encouraging results from a first study with dithionite bleaching though water soluble dyes cannot be removed in the flotation deinking process at all. Many open questions remain.”
Among INGEDE’s questions:
1. A bleaching step necessary for a small amount of inkjet printed papers within the mixture would be an additional step to the existing newsprint deinking process, resulting in additional costs and environmental impact by additional chemicals.
2. The result of additional process steps like bleaching is that higher targets than the ERPC Deinking Scorecard have to be fulfilled, or else the quality requirements of paper grades better than standard news cannot be achieved in the mills.
3. The preliminary research gives no evidence whether the dyes tested are just decolorized or irreversibly chemically decomposed. It has to be proven that the bleaching effect is irreversible and the color will not reappear with time; not under the oxidative pulping condition or later paper storage.
4. Also the relevance of the alleged results is open – which dyes are currently used in inkjet, and which share of them is bleachable? How do pigment-based inkjet inks behave in the reductive bleaching step?
“The DPDA's experiments have been done with bright woodfree papers. But for newspapers, which are a major expected growth sector for inkjet, usually wood-containing grades are used. The question remains what the results would be with the wide range of the paper grades on the market? Also downcycling higher grades to newsprint standards would not comply with the efforts of the European Union to promote the utilization of recovered paper in higher grades,” INGEDE reports.
INGEDE disagrees with DPDA's statement that INGEDE Method 11 does not match for water soluble inks, stating, “The fact is that water-soluble inks do not match with flotation deinking. INGEDE Method 11 does nothing else than simulate the key process conditions of typical deinking plants. Negative ERPC Deinking Scorecard deinking results*for paper printed with water-soluble inks indicate that these inks will not flotate in industrial deinking plants and therefore will have a negative impact on the recycling process.”
INGEDE has invited DPDA to engage in a scientific cooperation to develop a sustainable inkjet printing business that covers all environmental aspects from printing to recycling.
The "Deinkability Score" system is available from the ERPC (European Recovered Paper Council) website www.paperrecovery.org.