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DPDA Research Confirms Successful Deinking of Inkjet Printed Papers

May 18, 2010
BIRMINGHAM, UK—MAY 17, 2010—The Digital Print Deinking Alliance (DPDA) shared the first of a series of scientific research investigations into the deinkability of inkjet printed papers at the PTS/CTP Deinking Symposium held in Munich, Germany on April 29, 2010. In a study conducted by Centre Technique du Papier, (CTP) of Grenoble, France, a leading research organization and expert in the field of recycling technologies, inkjet prints were successfully deinked in a procedure designed to replicate a typical European mixed grade waste paper recycling system.

Presenting on behalf of the DPDA, Gary Williams, PE, Paper Scientist of InfoPrint Solutions Company reviewed the CTP research data with leading industry experts gathered at this International Deinking Symposium. “Our first study was intended to prepare a baseline for future testing of inkjet prints. We were pleased to learn that in this baseline case, nearly all samples were successfully deinked in test conditions that included bleaching”, said Williams.

The test samples were printed using standard aqueous dye based inkjet inks on uncoated woodfree paper. DPDA members prepared blind samples using 3 representative dye-based inksets for the study and tested under conditions designed to be representative of current deinking technology for processing mixed grades of recovered paper.

In the study, nearly all colorants were successfully deinked when hydrosulphite bleach was added after the repulping process. In one case, ink colorants were successfully deinked using peroxide only, which is a typical chemical used in the repulping step. In both cases, the bleached pulp met the deinked pulp quality requirements.

“This is very encouraging as a first study” said David Hatfield, R&D Manager for Kodak. “It provides some fact-based data that confirms what we have believed from over 40 years of inkjet printing. Most commercial recycling systems are robust and we have yet to observe a failure in any recycling system worldwide.”

It has been recently suggested that inkjet printed papers are not deinkable according to laboratory test conditions known as INGEDE Method 11. This lab test was primarily conceived to compare the deinking performance of gravure and offset prints on wood-containing papers. INGEDE Method 11 is sometimes cited as a simple lab-scale test to compare deinking performance of various printing technologies. “Method 11 may not be appropriate for all aqueous based inks, since the test is primarily a single step flotation test. With dye based inks, there is no ink particle to float, hence the futility of trying to meet this requirement.” said Dr Matthias Fromm, R&D Manager for Oce Printing Systems.
 

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