Nearly every one of the 1 trillion sheets of paper used in digital printers and copiers in the U.S. each year is made the same basic way: In a chemical pulping process, paper mills separate wood fibers in a water-and-chemical solution, then recover the cellulose, which comprises about 45 percent of the wood, to make paper. Leftover wood chemicals are burned for energy to run the process.
And for more than 20 years, paper scientists at Xerox wondered whether there was an alternative. Bruce Katz, a Xerox paper technologist, found it this year.
The new Xerox High Yield Business Paper™ introduced today uses half as many trees, is manufactured with less water and chemicals, and is produced in a mill that uses hydroelectricity to cut greenhouse gas emissions by 75 percent. Plus, because it's lighter weight than paper made by the traditional chemical process, it costs less to ship and mail. It is the first and only paper of its kind that performs reliably in digital printers and copiers.
How did Katz and the Xerox team do it, and what was the technical challenge they solved?
The new High Yield paper is made by a mechanical pulping method - the process that makes newsprint and the offset-printing paper that's used for some directories, catalogs and flyers. Wood chips are fed into large machines that grind the fibers loose to make the pulp. Because wood chemicals are not removed from the papermaking fiber, the process produces twice as much paper per tree - a yield of more than 90 percent.
When Xerox first experimented with mechanical paper more than two decades ago, its printers and copiers would not run reliably using the paper. There were two problems - the mechanical paper resulted in excessive dust contamination, and the heat necessary to fuse an image to the paper caused it to curl.
Mechanical paper did find other expanding markets, however, in offset printing, which is not a heat-based process. And Xerox recognized that the lighter but bulkier paper had attractive attributes. So Xerox scientists went back to the paper lab to see if they could make mechanical paper work in their products.
The problem that Xerox aimed to solve was keeping the paper from curling. That happened because paper actually expands or shrinks as it absorbs or releases moisture. The printer's fuser acts like a hot iron, fixing the image on the page and forcing moisture out of the paper. The mechanical paper curled, according to Katz, because the "back" and the "front" of the paper shrank at different rates.
In the Xerox media lab, scientists discovered the fibers were aligned in different patterns on each side of paper, resulting in uneven shrinkage. Working with the paper mill and employing statistical techniques, Katz developed a process that better distributed the fibers on both sides of the paper, reducing the curl so that the paper could run successfully in Xerox copiers and printers. Xerox has applied for a patent on the process. A surface treatment at the paper mill minimizes the paper dust, which had also caused operational problems.
The new paper has unique characteristics. In addition to its environmental benefits, a sheet of the High Yield paper weighs less than traditional 20-lb. bond paper made by the chemical pulping process because it is made with pulp that better blocks image show-through. In fact, there are about 10 percent more pages per pound of High Yield paper, and as a result, users can save money on their mailing costs.
That attribute makes it attractive for transaction printing applications such as bills and statements. However, like its newsprint cousin, the paper is not intended for archival use. And it has an 84 brightness compared with 96 brightness for Xerox's Color Xpressions+ ® paper, which is designed for color printing.
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