Soybean oil based inks for enhanced deinkability of litho prints

Abstract

Three types of food grade soybean oils were tested to determine if their byproducts could be utilized in the paper recycling industry. Free fatty acids were extracted from these commercially available soybean-oils.These acids were utilized in one loop air flotation deinking of litho-printed paper substrates. It was found that the three experimental fatty acids used in deinking differ in their chemical composition, namely acid number and Saponification number. The effect of each of the soy-oil free fatty acid on deinking was studied, quantified and compared to the standard INGEDE 11p procedure. The INGEDE method employs commercially available oleic acid and experimental fatty acids were tested as its replacement. INGEDE method 11p was slightly modified due to unavailability of a Hobart type pulper. Therefore, a MicroMaelstrom™ laboratory Pulper was used instead. The substrate used for deinkability study was heavily printed from both sides by sheetfed offset lithography. Due to heavy ink mileage, none of the four fatty acids had the power to deink such substrates in a one loop fotation recycling experiment. Besides INGEDE deinking evaluations, further deinking assessments were performed. Deinkability factors DEM_Lab and DEM_f were used to express the success of ink removal from the pulp, since ERIC instrument measuring equivalent residual ink concentration, considered in INGEDE scoring, was not available. Dirt count analysis of deinked handsheets was performed by scanning them using an Epson Perfection V500 Photo scanner followed by processing of scanned images by Verity IA Color Image Analysis software. Overall, it was found that two of the three experimental fatty acids (free fatty acid from everyday pure soy oil and the one from high oleic soy oil) performed better than the standard, using oleic acid. It was also found that these free fatty acids had lower acid number than the standard oleic acid, which could improve the deinking performance.