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Abstract

The U.S. Environmental Protection Agency (EPA) has funded

a pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the expertise to do so. Waste Minimization Assessment Centers (WMACs) were established at selected universities and

procedures were adapted from the EPA Waste Minimization

Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).

That document has been superseded by the Facility Pollution

Prevention Guide (EPA/600/R-92/088, May 1992). The WMAC

team at the University of Tennessee performed an assessment

at a plant that manufactures paper rolls, ink rolls, ink ribbons,

and magnetic and thermal transfer ribbon. The raw materials

required and the process operations used are specific to the

product being produced. Production of ink ribbons requires

application of ink to fabric ribbon and winding the ribbon into a

plastic cassette or onto a reel-to-reel assembly. To produce

rubber ink rolls, rubber sheets are kneaded until porous by a

series of operations and extruded into rubber cylinders which

are then filled with ink. Paper rolls are converted from bolt

paper through a series of cutting operations. The remaining

products, magnetic and thermal transfer ribbons, are produced

by applying proprietary coating mixtures to mylar film. The

assessment team’s report, detailing findings and recommendations, indicated that the plant generates a great deal of hazardous waste in the coating operations of the magnetic and thermal

transfer ribbon production and in the clean-up of production

equipment. The greatest cost saving opportunity recommended

to the plant involved the reuse of tracer ribbon in the ink ribbon

production line in order to reduce raw material purchase costs.

This Research Brief was developed by the principal investigators and EPA’s Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of an ongoing research

project that is fully documented in a separate report of the

same title available from University City Science Center.

Introduction

The amount of waste generated by industrial plants has become an increasingly costly problem for manufacturers and an

additional stress on the environment. One solution to the

problem of waste generation is to reduce or eliminate the

waste at its source.

University City Science Center (Philadelphia, PA) has begun a

pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the in-house expertise to do so. Under agreement with EPA’s

Risk Reduction Engineering Laboratory, the Science Center

has established three WMACs. This assessment was done by

engineering faculty and students at the University of

Tennessee’s WMAC. The assessment teams have considerable direct experience with process operations in manufacturing plants and also have the knowledge and skills needed to

minimize waste generation.

The waste minimization assessments are done for small and

medium-size manufacturers at no out-of-pocket cost to the

client. To qualify for the assessment, each client must fall

within Standard Industrial Classification Code 20-39, have gross

annual sales not exceeding $75 million, employ no more than

500 persons, and lack in-house expertise in waste minimization.

Waste Minimization Assessment for a Manufacturer of Paper Rolls,

Ink Rolls, Ink Ribbons, and Magnetic and Thermal Transfer Ribbon

United States

Environmental Protection

Agency

Risk Reduction

Engineering Laboratory

Cincinnati, OH 45268

ENVIRONMENTAL

RESEARCH BRIEF

Research and Development EPA/600/S-95/003 April 1995

Richard J. Jendrucko*, Brian T. Hurst*, and

Gwen P. Looby**

* University of Tennessee, Department of Engineering Science and Mechanics

** University City Science Center, Philadelphia, PA

E AP
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The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers, reduced

waste treatment and disposal costs for participating plants,

valuable experience for graduate and undergraduate students

who participate in the program, and a cleaner environment

without more regulations and higher costs for manufacturers.

Methodology of Assessments

The waste minimization assessments require several site visits

to each client served. In general, the WMACs follow the procedures outlined in the EPA Waste Minimization Opportunity

Assessment Manual (EPA/625/7-88/003, July 1988). The WMAC

staff locate the sources of waste in the plant and identify the

current disposal or treatment methods and their associated

costs. They then identify and analyze a variety of ways to

reduce or eliminate the waste. Specific measures to achieve

that goal are recommended and the essential supporting technological and economic information is developed. Finally, a

confidential report that details the WMAC’s findings and recommendations (including cost savings, implementation costs, and

payback times) is prepared for each client.

Plant Background

The plant manufactures small paper rolls for calculators and

cash registers, ink ribbon assemblies, rubber ink rolls, and

magnetic and thermal transfer ribbons. Total production for all

products is approximately 14 billion units/yr for this plant, which

operates 6,240 hr/yr.

Manufacturing Process

The manufacturing processes used to produce each type of

product are described below.

Ink Ribbon Assemblies

Raw materials for the process include oil-based ink, fabric

ribbons, plastic cassette components, plastic and metal spool

cores, and white fabric tracer ribbon.

Pre-mixed oil-based ink is applied to the fabric ribbon which is

wound onto a spool and stored until needed for product assembly. The majority of the inked ribbon is used in the production of cassette containment units, and a small portion of the

ribbon is used in reel-to-reel ribbon assembly.

The first step in cassette containment unit manufacturing is the

manual assembly of cassette components into one-half of a

housing. A white fabric tracer ribbon is then wound through the

internal system of rollers to designate the path that the inked

ribbon is to follow. The second half of the housing is then

bonded to the assembled cassette. Then, the inked ribbon is

inserted into the cassette; as the tracer ribbon is removed, it is

replaced with the inked ribbon.

In reel-to-reel ribbon assembly, the inked ribbon is cut to

length, inserted into a pair of metal or plastic spool cores, and

wound onto the cores.

An abbreviated process flow diagram for this process is shown

in Figure 1.

Rubber Ink Rolls

Raw materials used in the manufacture of rubber ink rolls

include synthetic rubber sheets, oil-based ink, toluene, plastic

and metal cores, and sodium nitrate. The rubber, toluene, and

sodium nitrate are placed into a rubber mill where the sodium

nitrate is kneaded into the rubber. (Toluene renders the rubber

more receptive to the sodium nitrate which makes the rubber

more porous, thereby facilitating ink absorption.) The resulting

rubber ball is formed into a rubber sheet.

The rubber sheets are allowed to air dry for several weeks.

Dried sheets are then cut to size and fed through an extrusion

molder which forms hard rubber cylinders. Next, the cylinders

are placed into a warm water wash to remove sodium nitrate

from the rubber. Following electric drying for one day, the

rubber rolls are soft and porous and able to absorb ink.

In order to introduce the ink into the rolls, they are placed in a

vat containing pre-mixed ink. A vacuum is placed on the vat to

remove air from voids, and when the vacuum is removed, the

ink is driven into the pores.

The flow diagram for this process is shown in Figure 2.

Paper Roll Conversion

Bolt paper, red powdered ink dye, rubber cement, and plastic

cones are among the raw materials used in paper roll conversion. The bolt paper is placed on a machine which slits the roll

for the production of smaller rolls.

The paper is marked with red ink along the first few feet of

each roll to serve as an end-of-roll warning to the eventual

user. The desired length of paper is wound onto a plastic core,

the end of the paper is cut free from the slitting machine, and a

light strip of rubber cement is applied to the paper end to

Fabric

ribbon

Oil-based

ink

Ink

application

Reel-to-reel

attachment Packaging

Storage

Plastic

components

White

tracer

ribbon

Cassette

assembly

Ink

ribbon

insertion Splicing

Cassette

cleaning

Storage Packaging

Figure 1. Abbreviated process flow diagram for ink ribbon assemblies.
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Existing Waste Management Practices

This plant already had implemented the following techniques to

manage and minimize its wastes.

• A paper compactor bales the trim waste from paper roll

conversion for recycle by an outside firm.

• Water used to cool the braking system on the paper conversion slitters is reused in the warm water wash tanks for the

rubber ink roll production line.

• Shrink-wrap trim waste from the paper roll conversion line is

baled for recycle by an outside firm.

• Aqueous-based cleaner is used instead of alcohol hand

cleaner in order to reduce the amount of hazardous waste

shipped offsite.

• Separate ball attrition mills are used for magnetic and thermal

transfer ribbon production to reduce the amount of clean-up

waste generated.

• Plant personnel, with the assistance of outside agencies, are

evaluating the composition of solid waste generated in order

to develop measures to reduce landfilled quantities.

Waste Minimization Opportunities

The type of waste generated by the plant, the source of the

waste, the waste management method, the quantity of waste,

and the annual waste management cost for each waste stream

identified are given in Table 1.

Table 2 shows the opportunities for waste minimization that the

WMAC recommended for the plant. The minimization opportunity, the type of waste, the possible waste reduction and

associated savings, and the implementation cost along with the

simple payback time are given in the table. The quantities of

waste currently generated by the plant and possible waste

reduction depend on the production level of the plant. All

values should be considered in that context.

Sodium nitrate

toluene

Synthetic rubber

Rolling

machine

Sheeting

machine

Air

drying

Washing Extrusion

molding Cutting

Electric

drying

Ink

application Weighing

Packaging Inspection Core

insertion

Storage

Plastic or

metal cores

Figure 2. Abbreviated process flow diagram for rubber ink roll production.

prevent the roll from unwinding. Groups of smaller rolls are

conveyed to a hydraulic press which separates the individual

rolls along score lines.

An abbreviated process flow diagram for paper roll conversion

is shown in Figure 3.

Magnetic and Thermal Transfer Ribbon

Raw materials used in the production of magnetic and thermal

transfer ribbon include mylar film and a variety of proprietary

materials.

Initially, the mylar to be coated is passed through a gauge to

determine material thickness. Then coating solution is applied

in a coater. The specific make-up of the coating solution is

determined by the type of transfer ribbon produced. The solution is applied to the moving mylar film in a thickness which is

measured with a gauge to ensure uniform product quality.

From the gauge the coated film goes through a drying tunnel.

After drying, the ribbon is wound onto a core and aged as

needed. Then the rolls are placed on a slitter and cut into

smaller rolls as determined by specifications.

Magnetic and thermal transfer ribbon production is shown in

Figure 4.

Paper rolls

Plastic cores

Rubber cement

Ink dye

solvent

Ink

mixing Slitter

Separation

of

individual

rolls

Edge

alignment

Storage Packaging Separation

Figure 3. Abbreviated process flow diagram for paper roll conversion.
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Proprietary

materials

Mylar

Staging Mixing

Gauge Coating Guage

Aging Rewind Drying

Slitting Packaging Storage

Figure 4. Abbreviated process flow diagam for magnetic and thermal

transfer ribbon production.

It should be noted that the financial savings of the minimization

opportunities result from the need for less raw material and

from reduced present and future costs associated with waste

management. Other savings not quantifiable by this study include a wide variety of possible future costs related to changing emissions standards, liability, and employee health. It also

should be noted that the savings given for each opportunity

reflect the savings achievable when implementing each waste

minimization opportunity independently and do not reflect duplication of savings that would result when the opportunities

are implemented in a package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, one additional measure was considered. This

measure was not analyzed completely because of its technological complexity and anticipated lengthy payback period. Since

this approach to waste reduction may, however, increase in

attractiveness with changing conditions in the plant, it was

brought to the plant’s attention for future consideration.

• Install an onsite wastewater treatment system to permit

removal of nitrate from washwater so that the water and the

nitrate can be reused.

This research brief summarizes a part of the work done under

Cooperative Agreement No. CR-814903 by the University City

Science Center under the sponsorship of the U.S. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.
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Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Generated Source of Waste Waste Management Method Generated (LB) Management Cost 1

Corrugated containers Component and raw material delivery Sold to recycler 294,070 $180

Off-specification ink Quality assessment of ink in ink ribbon production line Shipped back to vendor 310 1,870

Ink-contaminated solvent Cleaning of machines Shipped offsite as hazardous waste 5,540 21,610

Tracer ribbon Ink ribbon production Shipped to landfill 44,110 37,330

Evaporated toluene Rubber ink roll production Evaporates to plant air 11,920 7,950

Flashing and rejected rolls Extrusion molding of rubber Shipped to landfill 44,110 630

Overflow wash water Wash tanks in rubber ink roll production Sewered 55,136,010 18,980

Evaporated water Drying of rubber ink rolls Evaporates to plant air 3,625,440 1,720

Paper edge waste Slitter in the paper roll conversion line Compacted baled sold to recycler 391,240 (8,700) 2

Unusable stock paper Paper roll conversion line Sold to recycler 163,660 2,240

Waste shrink wrap Trimming from packaging of paper rolls Baled sold to recycler 8,500 1,590

Miscellaneous paper waste Various processes Shipped to landfill 441,100 6,270

Contaminated cleaning solution Magnetic transfer and thermal transfer ribbon production Shipped offsite as hazardous waste 41,240 21,030

Transfer ribbon edge trim Slitter in magnetic transfer and thermal Shipped to landfill 8,270 120

transfer ribbon production line

Evaporated solvents Drying tunnels in transfer ribbon production line Ducted outdoors 213,090 55,980

Contaminated solvents Coater in transfer ribbon production line Shipped offsite as hazardous waste 75,430 32,740

Chipboard and corrugated waste Various operations Shipped to landfill 294,070 4,180

Waste shrink wrap Various operations Shipped to landfill 132,330 1,880

Packaging plastic Various operations Shipped to landfill 73,520 1,040

Metal buckets Various operations Sold to recycler 1,020 1,610

Air compressor cooling water Air compressors Sewered 33,017,400 11,890

Miscellaneous wastes Various operations Shipped to landfill 147,040 2,090

1 Includes waste treatment, disposal, and handling costs, and applicable raw material costs.2 Net revenue received.

Table 2. Summary of Recommended Waste Minimization Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Minimization Opportunity Waste Reduced Quantity (LB) Per cent Savings Cost (yr)

Reuse white tracer ribbon in the ink ribbon Tracer ribbon 33,080 75 $27,330 $0 Immediate

production line instead of shipping it to the landfill.

Agitate the trays holding the rubber rolls in the Overflow wash water 27,568,000 50 11,290 7,400 0.7

wash-out tank to reduce the quantity of water

needed for sodium nitrate removal.

Reuse air compressor cooling water as wash- Air compressor cooling water 33,017,400 100 10,890 11,100 1.0

out tank make-up.

Segregate recyclable white trim waste from Paper edge waste —- —- 9,390 1,600 0.2

colored trim waste to increase the recycling

credit received by the plant. (No waste reduction will be achieved, but a significant increase

in recycling credit will result.)

Install a distillation unit in order to recover Ink contaminated solvent 4,440 80 3,100 5,980 1.9

solvent from ink solids for reuse in cleaning

operations.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/003