Chemists Sevim Erhan (left), Marvin Bagby and technician Dale
Ehmke (right) inspect the experimental setup for news ink biodegradation tests.
Soy Ink's Superior Degradability
Soybean inks have come a long way! Agricultural Research Service scientists
began developing soy inks in 1988 when the American Newspaper Publishers
Association and the American Soybean Association requested ARS help.
Now known as the Newspaper Association of America, this organization and the
soybean association had three objectives. They wanted a soybean-based ink to
lessen the industry's reliance on petroleum in ink products, and they wanted to
use more environmentally friendly inks. They were also seeking a soy ink that
could be cost-competitive with commercial petroleum-based printing inks.
Newspaper printing inks are made up of pigments carried by a thick fluid, or
vehicle. Made from petroleum-based chemicals, pigments are a component of all
inkseven soy inksto provide color. Because of the pigments and a
few other chemicals, soy ink isn't 100 percent degradable.
But ARS chemists Sevim Erhan and Marvin O. Bagby have developed new soy ink
formulas with more soybean oil, less pigment.
"Using more soy oil in the vehicle means that less pigment (black,
blue, red, and yellow) is needed, because the soy oil provides a lighter
vehicle," says Erhan. And soy-based printing inks contain no volatile
VOC emissions are restricted in many cities with air quality problems.
"Using more soy oil in ink formulas would make compliance with the Clean
Air Act easier for printers," says George Fuchs. He is manager of
environmental affairs for the National Association of Printing Ink
Bagby, who heads oil chemical research at the ARS National Center for
Agricultural Utilization Research in Peoria. Illinois, says the new ink is five
times as degradable as petroleum-based commercial inks. The degradability of
the ARS formula--the vehicle with the pigment--was demonstrated in tests
performed in 1994.
The results: 80 percent of ARS' soy ink vehicle degraded in 25 days. By
comparison, just 30 percent of an ink vehicle containing 67 percent soybean oil
degraded. And only 16 percent of a petroleum-based ink vehicle degraded in 25
days. Each formulation contained exactly the same amount and type of pigment.
"Making soy inks more degradable can help disposal problems associated
with using petroleum-based or hybrid soy-petroleum inks." says Erhan.
She's testing the various ink formulations in sewage sludge from the Greater
Peoria Sanitary District. The sludge should contain micro-organisms
representative of the types found in landfills throughout the country. The
results of this study will he ready in the spring of 1995.
"We're also developing the first scientific guidelines for evaluating
ink biodegradability," says Bagby. By Linda Cooke, ARS.
Erhan is in the USDA-ARS Oil Chemical Research Unit, National Center for
Agricultural Utilization Research, 1815 N. University, Peoria, IL 61604; phone
(309) 681-6532, fax (309) 681-6340.
"Soy Ink's Superior
Degradability" was published in the
January 1995 issue
of Agricultural Research magazine.