Deinking of inkjet at centre stage

Ralf Schlozer
Nov 11, 2011

Organised by the Centre Technique du Papier in Grenoble the first Technical Conference on deinking of digital prints took place on the 8th and 9th of November in Grenoble. The attractive mountain panorama of the Alps did not detract from the importance and challenges of deinking in today’s graphic arts industry.

Deinking is not only an environmental factor in the production and use of print (as is the total carbon footprint, health and safety at the workplace, and overall usage of resources), it is also an important economic factor for the operators of deinking plants and mills for paper with recycled fibre content. If graphic arts quality paper is to be produced from recovered fibres, certain quality parameters have to be met. While users’ expectations on paper quality are increasing, data from INGEDE (the International Association of the Deinking Industry) shows that the brightness of recovered fibres has been decreasing over the last six years.

With the projected rise of inkjet volumes and potential problems in deinking inkjet prints, inkjet took the centre stage of discussions at the conference. Based on InfoTrends data for 2010, inkjet contributes about 7% of the digital print volume in document printing, with the majority of that share being produced in home and office environments. The overall inkjet share is expected to increase to 13% of all digital production print by 2015, with production printing growing to just under half of that. Large format and packaging & label printing are not included in this view as these prints usually do not enter the waste paper stream for graphic paper recycling. Fortunately, universities, research organisations, and inkjet printer vendors have started to invest into research and over 20 papers were presented at the conference(program, at, giving details of the current status of deinking research. The vast majority of the papers focussed on inkjet printing and deinking. At the conference it turned out that technical details of the flotation deinking process are not fully understood yet and the renewed drive for research is leading to a better understanding of the processes involved. Also, the role of additives in inks, paper, or deinking chemistry is being explored. For example the DPDA (the Digital Print Deinking Alliance) sponsored two studies on how inkjet in a paper mix is affecting the quality of deinked fibres and how the results can be improved by changing deinking conditions. HP and UPM tested different prototype ink formulations, some with noticeably improved deinking results. Suppliers of paper chemistry and research institutions suggested additional approaches in additives or changes in the deinking processes.

Not all of the inkjet deinkability approaches suggested at the conference will be feasible on a production scale in a real life deinking plant. More research and discussions between inkjet vendors and paper mills will tell which approaches are suitable.

It needs to be stressed that the results of the lab trials are encouraging, but that the results either have to be turned into products (e.g. reformulated inks or paper coatings) or there need to be changes in the deinking processes. However it is good that this research work got started at a relatively early stage, before production inkjet volume begins to hit the waste stream at a higher rate. Today, production inkjet prints contribute not more than 0.05% of all paper printed. Considering that the majority of production inkjet output is in transaction and book applications, applications that are typically held onto by the user, the actual share of inkjet volume that gets to the point of paper collection is even less than 0.05%. By 2015, however, this could increase to 0.5% of all prints. Depending on the source and the targeted fibre quality, a range of up to 2% to 10% of inkjet print in the collected waste paper is deemed acceptable today by deinking facilities, so it will take some time for inkjet volume to hit the threshold. However under certain conditions, inkjet prints in local markets can cross the threshold earlier, if, for example, high volumes of an inkjet-printed local newspaper were produced.

The membership of the DPDA (HP, Kodak, Océ/Canon, and Ricoh/InfoPrint) is composed today of high production inkjet equipment suppliers, and it is good that these companies have taken the lead but most consumer, office, mid-range and specialty inkjet vendors are not yet involved, even though their products will contribute the bulk of inkjet prints in the waste paper for quite a while. We hope that more inkjet vendors in areas outside of production will join in seeing deinking as a common responsibility of all inkjet suppliers and not leave it to the forerunners in responsibility alone.

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