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.
"We wanted to test using conditions that simulate the total paper recycling process for mixed grades of paper, and understand the impact of inkjet printed papers in these commercial recycling systems. This research was conducted using 100% inkjet paper. We estimate that production inkjet's market share of total graphic printing is less than 1% today. Based on the projected growth rates of inkjet printing, we anticipate the deinking industry is capable at current volumes and that we have a few more years to jointly develop the appropriate technologies of paper, ink and deinking methods to ensure good deinking performance if and when the need arises." said Fromm.
According to Gregg Lane, Sr. Chemist at HP, "DPDA research will continue with other types of inkjet inks and paper combinations. It is important for the DPDA members that we work collaboratively with INGEDE and the paper industry. The benefits of inkjet printing are tremendous and it will penetrate many offset printing markets such as publishing and direct mail, bringing with it the reduced environmental impact of print-on-demand solutions using water-based inks."