Toner

:"For the Irish surname, see Toner (surname)."

Toner is a powder used in laser printers and photocopiers to form the printed text and images on the paper. In its early form it was simply carbon powder. Then, to improve the quality of the printout, the carbon was blended with a polymer. Toner particles are melted by the heat of the fuser, and bind to the paper.

In earlier machines, toner was poured by the user from a bottle into a reservoir in the machine. Modern machines feed directly from a cartridge. Empty cartridges are sometimes refilled by third party vendors.

Composition, size and manufacture

The specific polymer used varies by manufacturer but can be a styrene acrylate copolymer or a polyester resin. 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 [cite conference
first = Y.
last = Nakamura
authorlink =
coauthors = Kutsuwada, N.
title = Direct measurement of toner particle size
booktitle = Industry Applications Society Annual Meeting, 1989
pages = pages 2239–2242
publisher = IEEE Xplore
date = October 1–5, 1989
location =
url = http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel2/858/3081/00096951.pdf?arnumber=96951
doi =
id =
accessdate = 2007-08-03 ] or greater. To improve image resolution, particle size was reduced, eventually reaching about 8–10 μm for 600 dots per inch resolution. Further reductions in particle size producing further improvements in resolution are being developed through the application of new technologies such as Emulsion-Aggregation. [cite web
last = Mahabadi
first = Hadi
authorlink =
coauthors = Stocum, Anne
title = Xerox’s Emulsion Aggregation Toner – An Environmentally Friendly Technology
work = Xerox
publisher =
date = 2006-08-01
url = http://www.xerox.com/innovation/Xerox_ea_toner.pdf
format = PDF
doi =
accessdate = 2007-08-03 ] 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 resulted in toner granules with varying sizes and jagged shapes. To get a finer print, some companies are using a chemical process to grow toner particles. This results in more uniform size and shapes of toner particles. The smaller, uniform shapes permit more accurate color reproduction and more efficient toner use.

Clean-up

Toner 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.

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 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 can ignite dust in the vacuum cleaner bag or create a small explosion if sufficient toner is airborne. This may damage the vacuum cleaner or start a fire. Toner particles are so fine that they are poorly filtered by household vacuum cleaner filter bags and can blow through the vacuum motor or into the room.

If toner spills into the laser printer, 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.

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. The washing machine should be filled with cold water before adding the garment. Two complete wash cycles improves the chances of success. The first may use hand wash dish detergent, the second may use regular laundry detergent. Residual toner floating in the rinse water of the first cycle will remain in the garment and may cause permanent graying. A clothes dryer or iron should not be used until all toner has been removed.

Health risks

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 pyrol from the finished product.

According to recent research, some laser printers emit submicrometer particles which have been associated in other environmental studies with respiratory diseases . [cite news
last = Morawska
first = Lidia
coauthors = co-authors: He, Congrong; Taplin, Len
title = Particle Emission Characteristics of Office Printers
work = International Laboratory for Air Quality and Health (Queensland University of Technology); Queensland Department of Public Works
pages = 1–7
language =
publisher = SF Gate
date = 2007-07-10
url =http://cdn.sfgate.com/chronicle/acrobat/2007/08/01/printer_es063049z.pdf
format = PDF
accessdate = 2007-08-03 ]

Repackaging

Several toner manufacturers offer toner in wholesale quantites. Typically, bulk loose toner is sold in barrels or 10 kg bags (22 pound bags). Remanufacturers use the bulk toners to refill used empty toner cartridges. Some also replace worn parts in more complex cartridges.

References

* Hewlett-Packard, "Material Safety Data Sheets: HP LaserJet Print Cartridges", [http://www.hp.com/hpinfo/globalcitizenship/environment/productdata/ljmsdsuseng.html online]
* [http://www.malvern.com/LabEng/industry/toners/overview.htm Malvern Instruments] "Toner Particles – Monitoring Particle Size Distribution and Particle Shape"Notes: