New "unprinting" process removes text from glossy paper
Although eco-minded people do send their discarded paper off to be recycled, the recycling process isn't entirely environmentally-friendly – it generally requires a lot of power, and incorporates toxic chemicals. Now, however, scientists have developed a new method of simply removing the printed text from sheets of paper, so they can be reused.
First of all, we have already seen systems in which lasers are used to remove printer toner from standard copy paper. Unfortunately, though, those lasers damage the polymer coatings found on the fancier, glossier paper used for packaging, advertising and many other applications. As a result, such paper is rendered unfit for reuse.
Scientists from Rutgers University and Oregon State University recently set out to address that limitation, replacing the lasers with a xenon lamp.
Located 1.5 inches (38 mm) from the surface of semi-gloss paper upon which black toner had been printed, that lamp emitted flashes of broad-spectrum Intense Pulsed Light (IPL). These weakened the paper-toner bond, without adversely affecting the paper's coating. When an environmentally-friendly ethanol wipe was then gently drawn across the paper's surface, all of the toner came off, leaving a blank sheet of paper behind.
The process doesn't entirely remove untreated red, green or blue toner, as none of them absorb the IPL as thoroughly as the black. They can be completely removed, however, if they're first printed over with black toner.
It is hoped that once developed further, the technology could be incorporated into commercially-available home and office printers.
"Our method makes it possible to unprint and then reprint on the same paper at least five times, which is typically as many times paper can be reused with conventional recycling," says Rutgers Asst. Prof. Rajiv Malhotra, co-author of a paper on the study. "By eliminating the steps involved in conventional recycling, our unprinting method could reduce energy costs, pollution and greenhouse gas emissions."
The paper was recently published in the Journal of Cleaner Production.
Source: Rutgers University