Prototype Inkjet Web Press

Xerox has experimented with inkjet printing since the 1960s, earning more than 1,500 patents in the area. Xerox's purchase of Tektronix's inkjet technology helped it deliver the successful Phaser inkjet color printing line to market.

As for commercial-quality print, the experience of Xerox as well as the entire industry has shown that, while inkjet technology has many benefits for low-volume page printing and specialty applications such as wide-format and photo printing, toner-based imaging is more reliable at high-quality, high-volume production on the wide range of papers used in commercial printing. (The advantages of dry toner are reflected in the present requirement for specially modified or treated papers for nearly all high-volume production inkjet and liquid toned systems.)

One limiting factor in achieving higher quality production volume inkjet output on plain paper is that the technology most often employs water-based inks. Water on a paper surface is not always the printer's friend, especially when drying by absorption. It results in dot gain, softer dots, show through, muted colors, curled prints and limits substrate options. There are other matters to deal with as well, like getting rid of the water once you print. (To circumvent these issues, one vendor is printing a fifth liquid “bonding agent” to paper so the ink can “react,” reducing water-related issues.) Scientists are spending a lot of time and energy in R&D to overcome these issues.

Vaporizing water takes 40 times the energy of melting toner plastics. To run fast, water-based inkjet presses often require large heaters, coolers and dryers. The associated physical space, electrical subsystems and power consumption significantly increase operating costs, which dare we say is not so “green”—and affects power bills.

Xerox is taking a different, non-aqueous approach to inkjet printing by scaling up an array of inkjet heads and formulating inks that, when jetted to the paper, solidify on contact. This results in opportunities for faster sheetfed, as well as higher speed color web digital presses, that can use a very wide range of substrates, including most papers as well as many foils and plastics.

Using a proprietary manufacturing process, Xerox produces stainless steel inkjet heads that receive a viscous ink heated to near 100° C. Shot in the form of droplets to the substrate via piezo on-demand, they land on the surface but, unlike aqueous inkjet, do not have to penetrate paper fibers.

Stainless heads should last an extremely long time, are non-corrosive and highly resistant to the orifice erosion that plagues other approaches. The design is capable of jetting many types of inks, all closer in viscosity to conventional offset inks. It gives a good, sharp-edged hard dot, essential to high-end work. This approach brings Xerox a very stable and adaptive jetting platform, alternative ink selection (some with a toothpaste-like consistency) and a wide range of substrates. Xerox is testing this press (shown) with its solid ink advantages.

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