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Toner is a powder mixture used in laser printers and photocopiers to form the text and images on paper, in general through a toner cartridge. Mostly granulated plastic, early mixtures added only carbon powder and iron oxide; now there are mixtures that contain polypropylene, fumed silica, and various minerals for triboelectrification.[1] Toner using plant-derived plastic also exists as an alternative to petroleum plastic.[2] Toner particles are melted by the heat of the fuser, and are thus bonded to the paper.
In earlier photocopiers, this low-cost carbon toner was poured by the user from a bottle into a reservoir in the machine[citation needed]. Later copiers, and laser printers from the first 1984 Hewlett-Packard LaserJet,[3] feed directly from a sealed toner cartridge.
Laser toner cartridges for use in color copiers and printers come in sets of cyan, magenta, yellow and black (CMYK), allowing a very large color gamut to be generated by mixing.
Composition, size and manufacture
editThe specific polymer used varies by manufacturer but can be a styrene acrylate copolymer, a polyester resin, a styrene butadiene copolymer, or a few other special polymers. Toner formulations vary from manufacturer to manufacturer and even from machine to machine. Typically formulation, granule size and melting point vary the most.
Originally, the particle size of toner averaged 14–16 micrometres[4] or greater. Theoretically, for the perfect reproduction of dots and print features at 600 dpi, a particle size of about 5 μm is required and, at 1200 dpi, about 3 μm is required.[5] Further reductions in particle size producing further improvements in resolution are being developed through the application of new technologies such as Emulsion-Aggregation.[6] Toner manufacturers maintain a quality control standard for particle size distribution in order to produce a powder suitable for use in their printers.
Toner has traditionally been made by compounding the ingredients and creating a slab which was broken or pelletized, then turned into a fine powder with a controlled particle size range by air jet milling. This process results in toner granules with varying sizes and aspherical shapes. To get a finer print, some companies are using a chemical process to grow toner particles from molecular reagents.[7] This results in more uniform size and shapes of toner particles. The smaller, uniform shapes permit more accurate colour reproduction and more efficient toner use.
Clean-up
editToner can be washed off skin and garments with cold water. Hot or warm water softens the toner, causing it to bond in place. Toner fused to skin eventually wears off, or can be partially removed using an abrasive hand cleaner. Toner fused to clothing usually cannot be removed. Unfused toner is easily cleaned from most water-washable clothing. Because toner is a wax or plastic powder with a low melting temperature it must be kept cold while cleaning.
Toner particles have electrostatic properties by design and can develop static-electric charges when they rub against other particles, objects, or the interiors of transport systems and vacuum cleaner hoses. Because of this and the small particle size, toner should not be vacuumed with a conventional home vacuum cleaner. Static discharge from charged toner particles theoretically may ignite dust[8] in the vacuum cleaner bag or create a small explosion if sufficient toner is airborne. Toner particles are so fine that they are poorly filtered by household vacuum cleaner filter bags and can blow through the vacuum motor into the room. They can also cause overheating by clogging the motor filter and short circuit by their electric conductivity (carbon, iron) when they melt inside the motor.[9]
If toner spills into the laser printer or photocopier, a special type of vacuum cleaner with an electrically conductive hose and a high efficiency (HEPA) filter may be needed for effective cleaning. These are called electrostatic discharge-safe (ESD-safe) or toner vacuums. Similar HEPA-filter equipped vacuums should be used for clean-up of larger toner spills.
Health risks
editMuhle et al. (1991) reported that the responses to chronically inhaled copying toner, a plastic dust pigmented with carbon black, titanium dioxide and silica, were also similar qualitatively to titanium dioxide and diesel exhaust.[10]
Carbon black, one of the components of toner, is classified as "possibly carcinogenic" (Group 2B) by the IARC.
As a fine powder, toner can remain suspended in the air for some period, and is considered to have health effects comparable to inert dust. It can be an irritant to people with respiratory conditions such as asthma or bronchitis. Following studies on bacteria in the 1970s that raised concerns about health effects resulting from pyrrole, a contaminant created during manufacture of the carbon black used in black toner, manufacturing processes were changed to eliminate pyrrole from the finished product.
Research by the Queensland University of Technology has indicated that some laser printers emit submicrometer particles which have been associated in other environmental studies with respiratory diseases.[11]
A study at the University of Rostock has found that the microscopic particles in toner are carcinogenic, similar to asbestos. Several technicians who had been working with printers and copiers on a daily basis were observed for several years. They showed increased lung problems.[12] This confirms previous research published in 2006.[13]
Research at Harvard University has shown that, during printing, metal-oxide nanoparticles (defined as 100 nanometres and smaller, hence 0.1 micrometres and smaller) are released into the air from toner-based laser printers and multifunction devices. These machines use toner particles that are on average 20 micrometres in overall diameter, but the surfaces of the toner particles themselves carry innumerable tiny metal-oxide nanoparticles.[14] These ultra-small metal-oxide nanoparticles are highly bioactive and could cause harm to the lungs and also elsewhere in the body, given that particles 0.1 micrometres and smaller can cross biological membranes (including lung alveoli), thereby gaining access to all organs via blood circulation.[15] This remains an area of active research, with many knowledge gaps.[16][17]
Packaging
edit
The toner container can be a simple pack, for toner storage and transportation, or further, a consumable component of the printer. The most common way to consume toner is with a toner cartridge (or laser toner), as an office supply of a laser printer or photocopier.
Repackaging
editSeveral toner manufacturers offer toner in wholesale quantities. Typically, bulk loose toner is sold in barrels or 10 kg (22-pound) bags.
Toner is then used by a variety of industries in order to provide consumers with a finished laser toner cartridge.
Original Equipment manufacturers such as HP and Canon as well as manufacturers of compatible toner cartridges use the toner in the process of manufacturing a brand new OEM cartridge. Remanufacturers[18] of toner cartridges use the bulk toner in the process of creating remanufactured toner cartridges. Other companies use the toner to provide a toner refill service.
Most toner cartridges are available to the average consumer through retail outlets or local remanufacturing operations. Remanufactured and refilled toner cartridges are generally offered at a lower cost than original toner cartridges, having been either wholly remanufactured and then refilled with toner (the more-optimal method) or just refilled with toner (the less-optimal method).
Environmental considerations
editRecycling of pre-consumer waste toner is practiced by most manufacturers. Classifying toner to the desired size distribution produces off-size rejects, but these become valuable feedstocks for the compounding operation, and are recycled this way. Post-consumer waste toner appears primarily in the cleaning operation of the photo-printing machine. In early printers, as much as 20 to 25% of feed toner would wind up in the cleaner sump and be discarded as waste. Improved printer efficiencies have reduced this waste stream to lower levels, although on average 13% of the toner in each cartridge is still wasted.[19] Some printer designs have attempted to divert this waste toner back into the virgin toner reservoir for direct reuse in the printer; these attempts have met with mixed success as the composition of the toner will change by expending fusibles while retaining developer particles. Some consideration and fewer industry attempts have been made to reclaim waste toner by cleaning it and "remanufacturing" it.
Most toner goes to printed pages, a large fraction of which are ultimately recycled in paper recovery and recycling operations. Removal of toner from the pulp is not easy, and toner formulations to ease this step have been reported.[20] Hydrolyzable, water-soluble, and caustic-soluble toner resins have been reported, but do not appear to enjoy widespread application. Most paper recycling facilities mix toner with other waste material, such as inks and resins, into a sludge with no commercial use.[citation needed]
Toner-modified asphalt binder
editSince toner consists of several copolymers and it is a carbon-based material, it can be used as a useful modifier for the asphalt industry. It has been shown that inclusion of left-over burnt toner enhances the rheological and mechanical properties of asphalt binder, significantly. Such an application can be placed as an environmentally friendly alternative to prevent soil contamination due to the landfilling of waste toner.[21] Adding waste toner into asphalt binder and mixture decreases the binder's glass transition temperature and also, in the meantime increase the crystallization temperature as well.[22][23]
References
edit- ^ Simmons, Lee. "Inside Laser Printer Toner: Wax, Static, Lots of Plastic". Wired. WIRED.
- ^ "Archived". The US Environmental Protection Agency. Archived from the original on September 19, 2015. Retrieved 2023-05-23. [permanent dead link]
- ^ "HP Virtual Museum: Hewlett-Packard LaserJet printer, 1984". Retrieved 1 August 2024.
- ^ Nakamura, Y.; Kutsuwada, N. (October 1–5, 1989). "Direct measurement of toner particle size". Industry Applications Society Annual Meeting, 1989. pp. 2239–2242. doi:10.1109/IAS.1989.96951.
- ^ Ataeefard, Maryam (5 September 2013). "Production of carbon black acrylic composite as an electrophotographic toner using emulsion aggregation method: Investigation the effect of agitation rate". Composites: Par B. 64 (64): 78–83. doi:10.1016/j.compositesb.2013.08.076.
- ^ Mahabadi, Hadi; Stocum, Anne (2006-08-01). "Xerox's Emulsion Aggregation Toner – An Environmentally Friendly Technology" (PDF). Xerox. Archived from the original (PDF) on 2007-09-28. Retrieved 2007-08-03.
- ^ "Chemically Prepared Toner" (PDF). Galliford Consulting. 2006. Archived from the original (PDF) on 2006-10-15.
- ^ Robert Zalosh (2009). "Dust Explosion Fundamentals: Ignition Criteria and Pressure Development" (PDF). National Fire Prevention Association. pp. 7, 8. Archived from the original (PDF) on 2015-09-25.
- ^ "Step By Step 16 - Preventative Maintenance". Dan's Data.
- ^ Folinsbee, Lawrence J.; Frampton, Mark; Henderson, Rogene; Annie M., Jarabek; McGrath, James; Oberdörster, Gunter; Schlesinger, Richard B.; Warheit, David B. (April 1997). "Chapter 11. Toxicological Studies of Particulate Matter". Air Quality Criteria for Particulate Matter (PDF) (Report). Vol. 2. Office of Research and Development, Washington DC: United States Environmental Protection Agency. p. 664. EPA National Library:3 233718. Retrieved 2023-10-06.
- ^ Morawska, Lidia; He, Congrong; Taplin, Len (2007-07-10). "Particle Emission Characteristics of Office Printers" (PDF). International Laboratory for Air Quality and Health (Queensland University of Technology); Queensland Department of Public Works. SF Gate. pp. 1–7. Archived from the original (PDF) on 2013-06-02. Retrieved 2007-08-03.
- ^ "Laut Studie kann Tonerstaub Krebs verursachen" [Toner dust can cause cancer, according to study]. Berliner Morgenpost (in German). Retrieved 2017-08-06.
- ^ Ewers, U.; Nowak, D. (2006). "Gesundheitsschäden und Erkrankungen durch Emissionen aus Laserdruckern und Kopiergeräten?" [Health hazards caused by emissions of laser printers and copiers?] (PDF). Gefahrstoffe – Reinhaltung der Luft (in German). 66 (5). Dusseldorf: Springer: 203–210. ISSN 0949-8036. Archived from the original (PDF) on 2015-09-25. Retrieved 2015-09-23.
- ^ Powell, Alvin (October 24, 2018). "At Harvard Chan School, nano safety is no small concern (interview with Philip Demokritou)". The Harvard Gazette. Retrieved February 6, 2020.
- ^ Pirela, Sandra V.; et al. (October 9, 2018). "Engineered nanoparticles emitted from laser printers: Quantifying the health implications from nano-enabled products during consumer use. Quantifying Potential Acute and Chronic Exposure from 3D Printing/Additive Manufacturing" (PDF). Retrieved February 6, 2020.
- ^ Pirela, Sandra V.; Martin, John; Bello, Dhimiter; Demokritou, Philip (2017). "Nanoparticle exposures from nano-enabled toner-based printing equipment and human health: State of science and future research needs". Critical Reviews in Toxicology. 47 (8): 678–704. doi:10.1080/10408444.2017.1318354. PMC 5857386. PMID 28524743.
- ^ Pirela, Sandra V.; Sotiriou, Georgios A.; Bello, Dhimiter; Shafer, Martin; Bunker, Kristin Lee; Castranova, Vincent; Thomas, Treye; Demokritou, Philip (11 November 2014). "Consumer exposures to laser printer-emitted engineered nanoparticles: A case study of life-cycle implications from nano-enabled products". Nanotoxicology. 9 (6): 760–768. doi:10.3109/17435390.2014.976602. PMC 4671491. PMID 25387251.
- ^ "Whitepaper - Managing the cost of printing and copying". tonerguy.net. Gunn Trading Ltd. 2015. Archived from the original on 16 May 2015. Retrieved 16 May 2015.
- ^ "Asphalt mix made with recycled printer toner paves way for eco-friendly roads". The Guardian. 2015-05-20. Retrieved 2015-09-17.
- ^ Kittelberger, Steve; Sacripante, Guerino (2003). "Easily deinkable toner: A solution to the deinking problem for small mills". Pulp & Paper Canada. 104 (5): 37.
- ^ Notani, M. A.; Mokhtarnejad, M. (2020). "Investigating the rheological and self-healing capability of toner-modified asphalt binder". Proceedings of the Institution of Civil Engineers-Construction Materials. 173 (3): 123–131. doi:10.1680/jcoma.17.00072.
- ^ Notani, M. A.; Moghadas Nejad, F.; Fini, E. H.; Hajikarimi, P. (2019). "Low-Temperature Performance of Toner-Modified Asphalt Binder". Journal of Transportation Engineering, Part B: Pavements. 145 (3): 04019022. doi:10.1061/JPEODX.0000123.
- ^ Notani, M. A.; Moghadas Nejad, F.; Khodaii, A.; Hajikarimi, P. (2019). "Evaluating fatigue resistance of toner-modified asphalt binders using the linear amplitude sweep test". Road Materials and Pavement Design. 20 (8): 1927–1940. doi:10.1080/14680629.2018.1474792.
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