The task you describe has long been a goal of paper manufacturers,
printers and print users alike. Paper is a relatively inexpensive
information display medium, but it often has a very brief service
life, either because the information itself has a short useful life
(today's newspaper or a memo about this afternoon's meeting), or
because the document has a mistake that needs to be corrected. It
seems wasteful to just discard the used sheet, and various ways have
been sought to reuse or recycle it. I will describe the current
state-of-the-art, both in terms of what is now common commercially and
some of what is under development that has been disclosed.
Currently, the most economical approach to removing ink from paper for
recycling involves first converting the paper back to pulp, then
cleaning off the ink and other undesirable coatings, adhesives, etc.,
and then remanufacturing new paper from the cleaned pulp. Simplified
descriptions of this process can be found at the Le Desktop Paper
Encyclopedia:
https://www.ledesktop.com/Main/GeneralInfo/Encyclopedia/d.html
and also at Paper Online:
http://www.paperonline.org/cycle/deinking/deinking_frame.html
The pulping process together with stirring and heating with added
alkali and screening removes some contaminants. The pulp is then
washed with detergents, goes through a "flotation" process, and
bleached (usually with hydrogen peroxide). Any residual ink is
dispersed. Depending on the source materials and the kinds of printing
processes that were used, this may or may not remove enough of the ink
to be able to remanufacture white printing paper. For example, any
paper that has been printed with a laser printer has "toner" which
glues pigment to the paper with what amounts to a hot melt glue that
is difficult to remove. Some paper recycling facilities do not accept
laser-printed waste paper for that reason. Those that do may use the
resulting pulp to produce non-white paper products such as paper bags
and cardboard boxes.
For a much more detailed discussion of deinking as currently practiced
in the paper recycling industry, see the recently published book
"Recycled Fiber and Deinking" published by TAPPI, a technical
association for the paper industry. You can find a description of the
book and table of contents at:
http://www.tappi.org/index.asp?pid=2538&bhcd2=1036468007
Or you can read a simpler version of the recycling story from TAPPI
at:
http://www.tappi.org/paperu/all_about_paper/earth_answers/EarthAnswers_Recycle.pdf
The paper and printing industries have been conducting research for a
number of years to develop ways of easily "erasing" inked paper so
that it can be reused multiple times without pulping and
remanufacture. Some limited success has been achieved, but none of the
processes has yet to be commercialized on a large scale.
Some idea of the work that is currently underway can be gleaned from
recent industry conferences and patent activity. A representative list
of some recently published information includes the following:
US Patent #5,545,381, "Device for regenerating printed sheet-like
recording medium" (1996) describes "a device for regenerating a
sheet-like recording medium comprising a means for feeding a printed
sheet-like recording medium, a regenerating treatment means having a
step for eliminating image formed on said recording medium, a means
for discriminating and separating the recording medium whether the
treated recording medium is reusable or not and a means for storing
the separated reusable recording medium. Further, the present
invention discloses, as Examples, regenerating treatment means
treating sheet-like recording media printed with following toners or
inks with following degrading agent or a color eliminating agent; (i)
a toner comprising biodegradable plastics as a constituent ingredient
and an enzyme containing liquid as a degrading agent; (ii) a toner
comprising photodegradable plastics as a constituent ingredient and an
irradiation of a light containing a short wavelength light; (iii) a
toner or an ink using a coloring material comprising an
electron-donating color-forming organic compound and its developer and
a color-eliminating agent; and (iv) a toner or an ink using a coloring
material comprising an electron-accepting color-forming organic
compound and its developer and a color-eliminating agent."
US Patent #5,840,421, "Image recording medium capable of reuse" (1998)
describes "A reusable image recording medium having improved
capability of formation and removal of images such as toner images.
The medium comprises a substrate and a coating formed on a surface of
the substrate and having a recording surface with image forming
material-peelability, wherein the recording surface has a surface
smoothness of 200 seconds or lower as measured by a Bekk smoothness
tester."
US Patent #6,022,423, "Method for Deinking Paper," (2000) describes a
"method of deinking paper includes applying a deinking solution to the
paper to be deinked; the deinking solution being comprised of a
cleaning solution and a surfactant; abrading the paper to remove the
ink from the paper; and washing the paper to remove the deinking
solution from the paper."
"Erasable Thermal Recording Media" (Nishioka et al, Oji Paper Co.; p.
732 in Proceedings of IS&T's NIP 13: 1997, International Conference on
Digital Printing Technologies; available in libraries or via IS&T's
website: http://www.imaging.org )
describes a complete system involving thermal printing on a special
media which can be thermally printed and thermally erased for at least
100 repeated cycles.
CAP Ventures, an industry consulting research firm has just published
a 3-page analysis paper entitled "Reusable Paper: A Trend of the
Future?" available through their website for $100:
http://www.capv.com/Store/publications/pub00190.html
Quoting their abstract: " Major OEMs Canon and Minolta, in addition to
other companies, have been working on reusable paper. While the
concepts are similar for Canon and Minolta, both products are still
under development and are not currently available for commercial sale.
Both companies are closely watching the trends and needs of the
market, which will determine the eventual product launch."
Closely related to reusable paper are attempts to make "electronic
paper," paper-like products that can be written and erased
electronically. The two companies closest to commercialization of such
products are Gyricon and E-Ink:
http://www.gyriconmedia.com
http://www.eink.com
In summary, it is technically feasible to deink paper in a way that
leaves it reusable, but probably only for limited combinations of ink
and paper. Whether reusable paper ever catches on on a large scale
remains to be seen. The most widely used approach commercially at this
time involves reusing the paper fiber but not the sheet by repulping
and remanufacturing the paper. For office use on conventional rag
stationery paper, the best options probably remain the traditional
ones: reprint the page, scrape off the print (e.g., with a razor blade
or ink eraser) or cover over the erroneous print (white correcting
ribbon or tape, "white-out" or similar opaquing fluid). If you want to
use a chemical approach instead, it is possible, but only if you
select an ink system that you can match to your erasing chemistry such
as one of the ones described above in the various papers and patents.
Google Search terms (also used at US Patent
Office--http://www.uspto.gov):
Deinking paper
://www.google.com/search?q=deinking+paper
Reusable paper
://www.google.com/search?q=reusable+paper |
