ABSTRACT: When plastic film packaging is processed for reuse, residual ink colors the polymer and makes the polymer less stiff, weaker, and denser than the original material. These problems can be avoided if the printing is removed from the plastic film surface. In this study, a commercial polyethylene film with water-based ink printing was deinked (the ink was re- moved) using nonionic surfactants under a variety of condi- tions, and the effect of some parameters related to the de- inking process were quantified and optimized. Nonylphenol polyethoxylate, ethoxylated alcohol at a pH of 10, and ethoxylated amine at either acidic, neutral, or basic pH level were identified to be effective at deinking. The hydrophilic– lipophilic balance (HLB) value and the cloud point are useful parameters for characterizing the effectiveness of nonionic surfactants. For optimal deinking, the HLB of the nonionic sur- factants should be as small as possible or the cloud point as low as possible without the deinking temperature substan- tially exceeding the cloud point. Information related to scaleup of the process was also developed. Soaking plastic film in surfactant solution prior to mechanical agitation signifi- cantly decreased the needed agitation time to achieve a given level of deinking. Deinking decreases as the plastic/solution ratio (consistency) increases, and cutting plastic film into smaller pieces improves the deinking at moderate consis- tency. Increasing agitation speed also enhances the deinking. Experiments performed with pilot-sized paper deinking appa- ratuses demonstrated that deinking of plastic film using sur- factants is technically feasible. Paper no. S1289 in JSD 5, 363–374 (October 2002). KEY WORDS: Color measurement, deinking of plastic film, HLB, nonionic surfactant, plastic film recycling, tensile proper- ties, water-based ink. Environmental and solid waste disposal considerations along with shortages of raw material for plastic resins have increased the need for plastic film recycling. Currently, approximately 9% by weight and 20% by volume of U.S. mu- nicipal solid waste is composed of plastics; of this, 21 to 57% is plastic film (1–3). Only about 3.5% of all plastics and 5% of plastic films are now recycled (1,4). Replacement of plastic in packaging by other materials such as paper, foil, and glass has been considered as an al- ternative to reduce plastic waste, but this would result in a 400% increase in the weight of waste, a 200% increase in en- ergy consumption in making the alternatives, and a 210% increase in cost (2). Plastic packaging improves product se- curity and reduces spoilage and contamination of food products. The market demand for plastic film packaging in the United States is projected to grow at an annual rate of 3.1%, which will also increase the amount of plastic film re- quiring disposal or recycle (5). Limitations in the technol- ogy of sorting, cleaning, and reformulating the recyclate limit the plastic recycling rate. Since the source is better de- fined, in-plant plastic recycling is more successful than recy- cle of post-consumer plastic. However, if the plastic film is printed, re-extrusion of this plastic results in a product that can only be used to make low-value colored products such as trash cans, pipes, and signposts. Repelletized colored resins can crack owing to gases associated with ink decom- position (3,6,7). Effective film deinking technology could permit reuse of the polymer to produce clear films. Possible alternatives for plastic film deinking include using either or- ganic solvents or surfactants. However, surfactants have an advantage over organic solvents since the former are more environmentally compatible (6). Polymers used for films include low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene terephthalate, ethylene vinyl acetate, polyvinyl chloride, and polypropylene. The highest-volume resin used is LDPE because of its toughness, sealability, inertness, and action as a moisture barrier. LDPE has greater clarity and flexibility than HDPE, making it particularly valuable for clear films. Most plastic packaging is made of either LDPE, HDPE, or a mixture of LDPE and HDPE (8–10). The plastic film surface is almost always treated with one of several alternative surface treatment processes before printing to increase the surface energy of the plastic surface and enhance ink wettability. These surface treatments in- clude flame treatment, corona discharge, plasma treatment, and ultraviolet treatment. Treatment with corona discharge Copyright © 2002 by AOCS Press Journal of Surfactants and Detergents, Vol. 5, No. 4 (October 2002) 363 Presented at the 88th AOCS Annual Meeting & Expo, May 11–14, 1997, Seattle, Washington. *To whom correspondence should be addressed at University of Nevada–Reno, MS 170, Reno, NV 89557-0136. E-mail: hgecol@unr.edu Abbreviations: AEO X , ethoxylated alcohol; AMEO X+Y , ethoxylated amine; CMC, critical micelle concentration; DE*, total color differ- ence; DSC, differential scanning calorimetry; EO, ethylene oxide; HDPE, high-density polyethylene; HLB, hydrophilic–lipophilic bal- ance; LDPE, low-density polyethylene; NPEO 10 , nonylphenol poly- ethoxylate; TEM, transmission electron microscope. Deinking of Water-Based Ink Printing from Plastic Film Using Nonionic Surfactants Hatice Gecol a, *, John F. Scamehorn b , Sherril D. Christian b , Brian P. Grady b , and Fred E. Riddell c a Chemical Engineering, University of Nevada–Reno, Reno, Nevada 89557, b Institute for Applied Surfactant Research, University of Oklahoma, Norman, Oklahoma 73019, and c Kimberly-Clark Corporation, Neenah, Wisconsin 54956