United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH ,45268
Research and Development
EPA/600/SR-93/086 July 1993
? EPA Project Summary
Ink and Cleaner Waste
Reduction Evaluation for
Flexographic Printers
Gary D. Miller, William J. Tancig, Michael J. Plewa, and Paul M. Randall
The report summarized here de-
scribes the technical and economic ef-
fects that occurred when a flexographic
label print shop changed the type of
ink and cleaning agent used in the
shop. The changes were undertaken as
the best way to eliminate all hazardous
materials. The company's management
mandated the switch out of concern
for its employees and with the inten-
tion of limiting possible future waste
liability. Hence, the traditional alcohol-
based inks and alcohol solvent clean-
ing agents gave way to water-based
inks and an aqueous cleaner.
From a technical point of view, there
is general agreement in this shop that
the water-based inks yield better qual-
ity labels. Labor is reduced largely be-
cause the water-based inks are more
easily removed from the pans, rollers,
and plates. Ink splashes and spills are
also quickly removed by sponging ei-
ther with water or with the aqueous
cleaner.
As a result of these process modifi-
cations, solvent emissions to the plant
air have been reduced about 80%. The
toxicity of the gaseous and liquid
wastes has also been reduced approxi-
mately 90%. Hazardous liquid wastes
have been eliminated while wastewater
sent to the sanitary sewer has in-
creased. Solid wastes have remained
relatively unchanged.
The water-based inks brought about
major savings because most of the liq-
uid wastes do not now require disposal
as hazardous wastes. The ink wastes
are presently acceptable at the local
public waste treatment plant The clean-
ing towels and wipers are now either
rinsed within the plant or sent to a
commercial laundry; formerly, they had
to be labeled as hazardous and segre-
gated for special disposal. Though un-
treated ink washes are acceptable to
the waste treatment plant, the company
has chosen to filter theirs through a
special absorbent to remove all color.
The used absorbent is acceptable in
the local landfill.
For this company, these changes in-
volved no capital expenditures other
than the absorbent unit. With the levels
of various alcohols evaporated during
printing now greatly reduced, the em-
ployees enjoy a cleaner and healthier
plant environment.
This summary was developed by
EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the WRITE program
demonstration that is fully documented
in a separate report (see ordering in-
formation at back).
Introduction
A Waste Reduction Innovative Technol-
ogy Evaluation (WRITE) (with the Illinois
Department of Energy and Natural Re-
sources [ENR] and the U.S. Environmen-
tal Protection Agency [EPA]) was designed
to (1) quantitatively compare the volume
and toxicity of any waste generated dur-
ing printing and released as gaseous, liq-
uid or solid waste before and after switch-
ing to water-based inks and a detergent
cleaner and (2) determine the economic
Printed on Recycled Paper
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effect of modifying a traditional printing
technology.
This project evaluated flexographic print-
ing of labels in commercial quantities. The
participating firm was a narrow-web
flexographic printer, MPI Label Systems,
Inc., of University Park, IL MPI Label Sys-
tems' plant is in a modern, one-story, clear
span building. Its printing capabilities are
based on several narrow-web flexographic
presses each capable of printing one to
six colored inks.
Several years ago, management di-
rected the company's eight plants to elimi-
nate the use of all hazardous and toxic
materials. The incentives included a de-
sire to eliminate employee exposure to
any liquid or gaseous hazards resulting
from handling these materials and an equal
desire to minimize the possibility of future
litigation resulting from use of such sub-
stances.
The decision forced each plant to sub-
stitute water-based inks for alcohol-based
inks, and at the same time, change from
alcohol solvent cleaning agents to aque-
ous type cleaning agents.
Water-based inks were substituted for
those formulated with alcohols since the
water-based inks were already available
on the commercial market. Implementing
this change, however, required extensive
cooperation between the ink manufacturer
and the printing plant because of different
printing conditions, changing customer re-
quirements, and the paper stock require-
ments associated with the water-based
Inks.
Because water-based inks are easier to
remove or clean with aqueous agents
when wet, a terpene-type (d-limonene)
cleaner was initially tried. Later, a dilute
aqueous solution of detergent proved to
be even easier to handle, odor free, and
less expensive. As cleaning agents are
Introduced to the commercial market, MPI
Label Systems routinely tests them to de-
termine if they can improve their process
and be even safer for the environment. ,
Printing Background
Most printing operations function in a
similar manner. Ink of the desired color
and viscosity is supplied to the printing
press where a rotating roller continually
removes a thin layer of ink from the reser-
voir. This thickness is carefully and pre-
cisely controlled. Ink is then applied to the
printing plate, followed by transfer to the
printing stock. In the case of flexography,
the plate is flexible and is wrapped around
a separate roller. Customarily, when print-
ing labels, a continuous sheet of paper
receives an ink imprint of the image on
the plate. When more than one color is
involved, a separate plate is used for each
color; each plate must be in registration
for all the colors to be properly placed and
rendered.
Paper stock for most labels is a two-ply
material. The top ply, on which the labels
are printed, normally has its bottom sur-
face coated with an adhesive that ad-
heres to the silicone-treated top surface
of the bottom ply. Immediately after the
plate applies ink to the label stock paper,
the web moves through a heated drying
area (70°C for this plant's press). Each
dry label is then pressured by a steel
cutting die that physically severs the top
ply of label stock but does not remove the
label from the surrounding blank stock.
Moments after a label is severed from the
surrounding stock by the die cutter, the
print-free waste paper stock is peeled away
from the bottom ply and collected on a
separate roll destined for incineration or a
landfill. The labels, still adhering to the
bottom ply, go to another roll and are
processed for shipment to customers.
Waste Reduction
Wastes are generated at most stages
of the printing process. Ink wastes result
when the reservoir, the various rollers,
and the printing plate are cleaned at the
end of a run. Excess ink in the reservoir
can be collected for reuse, but the other
ink quantities removed during cleaning
generally remain as waste. MPI Label Sys-
tems keeps a 50-gal barrel of water adja-
cent to each press. During cleanup when
water-based inks are used, soiled parts
and cleaning towels are rinsed in this wa-
ter to remove ink residues. At the end of
the week, barrels of rinse water are trans-
ferred to an ink splitting device that ab-
sorbs the various ink pigments on a cellu-
lose-based porous material; the nearly
clear filtrate passes through for disposal
in the sanitary sewer, with permission from
the local water treatment plant. The pig-
ment-colored cellulose is accepted at the
local landfill along with paper wastes from
the print line. Some paper wastes accu-
mulated during setup operations are un-
avoidable, although an experienced printer
is usually able to minimize them. Excep-
tional amounts of waste labels are, how-
ever, occasionally generated during the
production of multicolor labels because of
color registration difficulties. The adhesive-
based, print-free stock surrounding each
label is collected on a separate waste roll.
Most printing processes begin with a
photographic negative. Developing the
negative generates a number of chemical
wastes that usually require special treat-
ment for either recycling or disposal. The
photographic chemicals used in produc-
ing the master negative account for small
amounts of waste, though the silver is
usually recovered. At least for flexography,
the plate is developed after exposure to a
bright light and by washing away the un-
exposed areas with a solution.
In nearly every step of the printing pro-
cess, some volatile chemicals are released
into the air. In some cases, this occurs as
a result of process design; in other in-
stances, it occurs simply because of the
volatile nature of the materials. These
volatiles can range from water to various
alcohols, plastic ; thickeners, homogeniz-
ers, and chemical diluents. Each ink loses
volatile material as a result of storage in
the open.ink reservoir; during rotation on
the various rollers that determine the film
thickness to be applied to the plate; as
lost material on the plate; and during the
heated drying phase. The ink ultimately
reaches a rub-off-free state after the ma-
terial on which it is printed passes through
the heated drying zone. In addition to vola-
tile losses associated with the inks, adhe-
sive and solvent molecules evaporate from
the adhesive-coated label surfaces as a
result of simple exposure to the air. As
with many chemicals, only a few mol-
ecules per cubic meter can, in some cases,
create breathing .distress for hypersensi-
tive individuals, and the sensitive individu-
als must leave the contaminated area.
Cleaning agents used on the press will
also evaporate into the air. These clean-
ing solvents can range in type from water
with small concentrations of detergents to
various organic chemicals.
Procedure
The project compared the volume and
toxicity of any gaseous and liquid wastes
produced by the printing process before
and after switching to water-based inks
and an aqueous cleaner and then deter-
mined the economics of such process
changes.
Laboratory measurements estimated the
solvent loss from the inks by measuring
the portion of the inks that evaporate and
the materials used in the plant and by
basing the calculations on the composi-
tion of the inks. Laboratory measurement
of solvent loss by evaporation for each ink
was used to estimate the percent volatiles.
The amount of ink on waste labels Was
estimated by subtracting the total number
of labels printed from the number of labels
acceptable as product. These results were
compared with the weight of volatiles in
each ink as reported on i:he material safety
data sheets. The alcohol-based ink con-
tains six volatile components; four of them
-------
are alcohols, and ethyl alcohol and iso-
propyl alcohol are present in the largest
amounts. By comparison, the water-based
ink contains four volatile components, with
most of the volatiles being water (65%)
and isopropyl alcohol (5%). Some of the
water, about 24%, is bound to the resins
and does not evaporate on drying. Both
the solvent cleaner previously used and
the new detergent cleaner contain over
97% volatiles; again the detergent cleaner
is mostly water. The amount of ink and
other materials disposed of as liquid waste
was determined gravimetrically, using a
special rotating apparatus that exposed a
continual and new thin film of ink to a
constant, low-pressure air jet while the
entire apparatus was kept at 70°C, for two
printing runs. This approach minimized
burning, charring, or spattering of ink as
its viscosity continued to increase during
solvent evaporation. This particular test
was run in triplicate; samples achieved
constant weights, ± 5 mg.
Results
Emissions from Inks and
Cleaners
Because MPI Label Systems no longer
uses alcohol-based inks nor permits them
in the plant, the actual emissions of these
inks during in-plant runs was not mea-
sured. The percent solids in each ink (and
indirectly, thereby, the amount evaporated)
was determined gravimetrically in the labo-
ratory. These measurements (Table 1) in-
dicate the proportion of the alcohol-based
ink that evaporated was 48% compared
with 56% to 62% for the water-based inks.
To .estimate emissions that would have
resulted from using solvent-based inks, it
was assumed that the same amount of
solids (or ink retained on the labels after
drying) would have been used for printing
the labels with alcohol-based inks as was
used in printing with water-based inks.
Then the total amount of ink that would
have been used and the weight evapo-
rated were calculated by using the per-
cent loss factor determined in the labora-
tory. Since a smaller percentage of alco-
hol-based ink was lost to evaporation,
more solids per gram of ink would be
applied to the labels than with the water-
based ink. Thus, less total alcohol-based
ink was assumed to be used and less
total weight of components would be lost
via evaporation. The in-plant measurement
results are shown in Table 2. The water-
based inks-use data were obtained during
two evaluated runs: One run was approxi-
mately 55,000 labels; the other about
250,000. In each case, the total weight of
ink materials added and the weight of
materials remaining at the end of the run
were measured. The difference was the
weight of material that was assumed to
be either evaporated to the shop air, dried
on the labels, or wasted. The portions
evaporated and retained as solids were
calculated with the use of the laboratory
data presented in Table 1.
The press operators at MPI Label Sys-
tems estimated that about the same total
amount of either ink is required for a job.
Thus, this emission analysis is conserva-
tive for the alcohol-based ink. For com-
parison, the volume of alcohols evapo-
rated during a printing run was calculated
from the known formulations based on the
total amount of ink used during each print-
ing run. The laboratory evaporation loss
results also agree quite well with the total
volatile component data shown on the
material safety data sheets.
Concentrations of each volatilized com-
ponent in the plant air were calculated
Table 1. Weight Loss Data from Laboratory Evaporation at 7CPC
Material Initial wt.,
gm
Water-based 12.17
black ink
Water-based 12.05
green ink
Water-based 12.22
purple ink
Alcohol-based 15.38
black ink
Detergent cleaner 12.56
Average of triplicate runs
Dry wt., Wt. loss,
gm gm
5.30 6.87
5.04 7.01
4.66 7.57
7.99 7.38
0.28 2.22
Std. dev.,
gm
0.42
0.21
0.20
0.60
0.03
%Loss
56.5
58.2
61.9
48.0
97.8
based on the volume of air in the shop
area and the air exchange rate (Table 3)^
These concentrations are the levels ex-
pected during continual operation of the
press assuming all six print stations are
being used to apply ink. Ammonia and
dimethanolamine levels were highest for
the water-based inks. For the alcohol-
based inks, isopropyl alcohol, methyl al-
cohol, n-propyl alcohol, ethyl alcohol, ethyl
acetate, and Varnish Makers and Painters
(VM&P) naphtha levels were higher. :
Liquid Wastes
The amount of liquid wastes generated
from printing with the water-based inks
was measured during the two printing runs.
These wastes (consisting of ink left in the
reservoir, and on rollers, gaskets, and
plates) were produced during cleanup at
the end of each run. For the green labels,
24.6 g of ink and 44.3 g of cleaner were
used. A more experienced operator only
produced 56.4 g of liquid waste from prirtt-
ing the purple labels.
The concentration of ink and cleaner
components estimated to be present in
the wastewater from the facility (before
treatment) is shown in Table 4. These
concentrations were estimated assuming
that each day the ink pans were all in Use
and cleaned out into a 50-gal tank, every
week the tank was discharged, and most
of the waste resulted from use of the
cleaners. From the water-based inks, over
85% of the liquid waste was water. Other
constituents of concern were acrylic resin,
azo pigments, and isopropyl alcohol. Con-
centrations of constituents from the alco-
hol-based inks, if they had been disposed
of in the same manner, were estimated to
be much higher. Toluene, isopropyl alco-
hol, acetone, resins, pigments, and ethyl
alcohol were the major constituents of con-
cern.
Before implementing the use of water-
based ink and detergent cleaner, the sol-
vent-based waste ink was disposed of as
a hazardous waste and was thus mani-
fested. No liquid ink wastes were sent to
the sanitary sewer before the use of wa-
ter-based inks. Although the total amount
of liquid solvent-based waste manifested
in a year was on company records, this
information was considered proprietary and
was not made available for the purposes
of this project. It was not possible to di-
rectly measure the amount of alcohol-
based ink and cleaner wastes that would
have been generated from printing runs
similar to those evaluated with the water-
based inks. Company officials reported
that in their experience, the amount of
solid and liquid wastes generated are es-
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Table 2. In-Plant Ink Use and Estimated Emissions
Green Labels
Parole Labels
Measured
Water-based
ink
Alcohol-based
ink
Water-based Alcohol-based
ink ink
Total Ink used,
Ink solids on
labels,
Weight
evaporated, g
1459
609.8
849.1
1175
609.8
565.2
399.2
152.1
247.1
293.1
152.1
141.0
Table 3. Estimated Concentration of Air Emissions, \ig/L
Components
Water-based
ink
Purple Labels
Green Labels
Alcohol-based
Ink
Water-based
ink
Alcohol-based
ink
Isopropyl
alcohol
Ammonia
5.3
1.1
7.3
6.0
1.2
9.2
Dimethyl 1.1
ethanolamlne
Water 58
Methyl alcohol
n-propyl
alcohol
Ethyl alcohol
Ethyl acetate
VM&P naphtha
~
-
3.3
4.5
15
2.9
4.6
1.2
62
4.1
5.6
18
3.6
5.7
* Not applicable.
sentially the same for both ink types. The
main difference, however, is that liquid
wastes from the water-based inks did not
have to be disposed of as hazardous
wastes for this project.
Evaluation of Changes in
Toxicity
Toxicity reduction evaluations for the
Ink and cleaner wastes were accomplished
with the Degree-of-Hazard scheme devel-
oped and used by the Illinois Hazardous
Waste Research and Information Center.
The equivalent toxic concentration was
calculated for four printing scenarios: (1)
green alcohol-based ink with solvent-based
cleaner; (2) purple alcohol-based ink with
solvent-based cleaner; (3) green water-
based ink with detergent cleaner; and (4)
purple water-based ink with detergent
cleaner. For estimated emissions to the
air, the alcohol-based inks and cleaners
had relative toxicities about 10 times higher
than those for the water-based emissions.
The same reduction was found in the liq-
uid waste comparison. In actuality, no liq-
uid wastes were discharged to the sewer
when the company was using alcohol-
based inks and cleaners. Therefore, the
relative toxicity of these wastes increased
from zero. Offsetting this is the fact that
the undiluted alcohol-based wastes were
previously sent to a landfill in the waste-
containing drums.
Economic Analysis
The approximate annual savings at MPI
Label Systems resulting from the ink and
cleaner change is estimated by the plant
manager to total at least $16,500 (Table
5). There is essentially no difference in
raw material costs'for the inks and clean-
ers. The overall productivity of the plant
has increased, but the economic value pf
this increase could not be determined.
Annual waste disposal and handling ac-
count for at least a savings of $15,000.
The facility saves about $500 each year
because of a lowered insurance premium
based on improved working conditions.
Savings because of new wiping materials
(nondisposable) equals about $1,000 an-
nually. '
Conclusions ;
The results from the change to water-
based ink and cleaner at MPI Label Sys-
tems are both definite and significant:
Solvent emissions to the plant air have
been reduced by at least 80%.
Toxicity of these emissions has gone
from potentially hazardous to humans
to essentially harmless.
Solid waste generated and destined
for local landfills has been noticeably
reduced in volume and is no longer
classified as hazardous. This waste
is mostly bu|k paper for which a
recycling system is being sought.
Additionally, these changes neither in-
curred capital costs nor increased opera-
tional expenses. Rather, the plant annu-
ally enjoys a significant saving associated
with reduced waste disposal, insurance,
and cleaning material costs. The shop
manager at MPI Label Systems contends
that associated benefits include
1. Water-based jnks are easier to clean
from pans, plates, and rollers when
wet.
2. Water-based ink waste is more easily
disposed.
3. Water-based ink spills are easier to
clean up when wet.
4. Waste going to a landfill is no longer
classified as hazardous, reducing MPI
Label Systems' long-term liability.
5. Expensive solvents are not required
for cleaning.
6. Employees are enjoying a cleaner,
safer work environment.
7. Customers are receiving a better
product.
8. Corporate concerns regarding
hazardous materials are minimized.
The full report Was submitted in fulfill-
ment of CR-815829 by Illinois Hazardous
Waste Research and Information Center
under the sponsorship of the U.S. Envi-
ronmental Protection Agency.
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Table 4. Estimated Concentrations of Components in Wastewater,
Purple Labels
i Components
Isopropyl
alcohol
Ammonia
i Dimethyl
ethaholamine
Water
Resins
: Pigment
Methy alcohol
n-propyl
alcohol
Ethyl alcohol
Ethyl acetate
VM&P naphtha
Toluene*
Acetone*
Isopropyl
alcohol*
Diacetone
alcohol*
' Water*
Water-based
ink
159
26.6
26.6
2090,
2.4
1.0
-
-
-
-
-
-
-
-
-
44.3
Alcohol-based
ink
344
*
-
-
713
713
159
211
690
132
211
6370
2350
2350
634
-
Water-based
ink
317
52.8
52.8
4230
1290
528
-
_
-
-
-
-
-
-
-
11700
it c-g^c/a
Alcohol-based
ink
687
-
-
_
1510
1510
291
423
1400
264
423
6370
2350
2350
634
-
* Not applicable.
* Constituents of cleaners
, Table 5. Economic Summary of Savings Using Water-Based Inks and Cleaners
Parameter Savings
Water-based inks
; Printing speed
' Raw Materials
. Waste disposal and handling
Aqueous cleaners
Disposal
Raw materials
Overall Savings
. Insurance liability
; Inventory
Wiping materials
Annual total
Approximately 10% faster
None
Minimum annual savings = $10,000
Minimum annual savings = $5,000
None
Approximately $500/yr
None
Annually at least $1,000
At least $16,500
ArU.S. GOVERNMENT PRINTING OFFICE: 1993 - 750-071/80016
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Gary D. Miller and William J. Tancig are with Hazardous Waste Research and
Information Center, Champaign, IL 61820. MichaelJ. Plewa is with University
of Illinois at Urbana-Champaign Institute for Environmental Studies,
Champaign, IL 61820.
Paul M. Randall is the EPA Project Officer (see below).
The complete report, entitled "Ink and Cleaner Waste Reduction Evaluation for
Flexographic Printers," (Order No. PB93-191286; Cost: $17.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
i EPA
PERMIT No. G-35
EPA/600/SR-93/086
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