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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. In an effort to assist these manufacturers 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 That document has been superseded by the Facility Pollution Prevention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

Colorado State University performed an assessment at a plant

that manufactures three varieties of pressure-sensitive tape.

Tape production involves the three basic operations of backing

fabrication, coating, and slitting. Three separate coating operations are used, as determined by the type of tape being

manufactured (natural rubber, acrylic, or hot-melt). The team’s

report, detailing findings and recommendations, indicated that

waste natural rubber adhesive is shipped offsite for disposal in

large quantities, and that significant cost savings could be

achieved by redesigning the adhesive applicator on the coater

for natural rubber adhesive.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research 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

National Risk Management Research Laboratory, the Science

Center has established three WMACs. This assessment was

done by engineering faculty and students at Colorado State

University’s (Fort Collins) 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 pollution prevention opportunity 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 pollution

prevention.

The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers, and

reduction of waste treatment and disposal costs for participating plants. In addition, the project provides valuable experience for graduate and undergraduate students who participate

in the program, and a cleaner environment without more regulations and higher costs for manufacturers.

Pollution Prevention Assessment for a Manufacturer of

Pressure-Sensitive Adhesive Tape

ENVIRONMENTAL

RESEARCH BRIEF

Harry W. Edwards*, Michael F. Kostrzewa*, and

Gwen P. Looby**

E AP

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/023 August 1995

* Colorado State University, Department of Mechanical Engineering ** University City Science Center, Philadelphia, PA
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Methodology of Assessments

The pollution prevention opportunity 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

This plant manufactures adhesive tape that is distributed nationally and internationally. Over 100 million m2 of tape are

produced each year during 24 hr/day production.

Manufacturing Process

Three varieties of pressure-sensitive adhesive tape—natural

rubber, acrylic, and hot-melt—are produced by the plant. Several colors of tape, sold in rolls of 1-1/2 to 6 inches in width, are

manufactured.

Tape production involves the three basic operations of backing

fabrication, coating, and slitting. The backing, or non-stick surface of the tape that gives it strength, is made from polypropylene film in a cast-film process. Polypropylene pellets are

melted in electricallyheated extruders, and the resulting molten

plastic is applied to the top of a rotating cylinder and cooled

into a sheet in a water bath at the bottom of the cylinder.

The material is pulled from the die with a width of about one

meter and a thickness of 1.5 to 2 mm. Then the film is

stretched by rollers to over five times its original length and by

mechanical “fingers” to about seven times its original width as

it is heated in an oven. After stretching, the backing is cooled

over water-cooled rollers. Next, the edges of the backing are

trimmed; these trimmings as well as other backing waste, are

shredded, melted, pelletized, and reused.

The final stage in the backing process involves the use of a

pull-rod stand, where 12,000 m of backing material with a width

of 6 m are rolled onto a balanced steel roller. A bridge crane

transports the rolls to a slitting machine, where the rolls are

unrolled, cut to smaller widths, and re-rolled into shorter lengths.

A small percentage of the resulting rolls is sold as a finished

product. The remaining rolls are transported to the coating

areas.

Three separate coating operations are used to make the three

varieties of tape produced. Production of acrylic tape begins by

unwinding the film and feeding it into the coating machine.

Acrylic adhesive is applied to one side of the film and the tape

is then passed through a steam heater to dry the adhesive

while maintaining proper moisture levels. Finished tape is then

wound onto temporary rollers.

Fabrication of natural rubber tape follows a similar process.

Film is unwound and fed into a coater. A release coat, which

prevents the tape from adhering to itself on the roll, is applied

to one side of the film. A primer coat, which prepares the

surface of the film for the adhesive, is applied to the other side.

Then the tape passes by a reservoir where the natural rubber

adhesive flows onto the film in a thin coat. The film passes

through a chamber where the solvent carriers evaporate. The

vapors are collected using a recovery system and reused.

Finally, the finished tape is wound onto temporary rollers.

Hot-melt tape fabrication begins by unwinding the film and

feeding it into a coater. A release coat is applied to one side of

the film and the hot-melt adhesive, which has been melted with

electric heaters, is applied to the other side. Evaporated solvent carrier is recovered and reused as in the natural rubber

tape production process. The finished tape is then wound onto

temporary rollers.

The temporary rollers from the three coating operations are

taken to the slitting area, where the tape is unrolled, slit, and

rewound onto paper cores of various widths. The finished tape

rolls travel down a conveyor to a boxing station. After inspection, the boxes are sealed, sorted, loaded, and stored or

shipped to customers.

An abbreviated process flow diagram for the production of

pressure-sensitive adhesive tape is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• Water usage for clean-up of the acrylic tape coater is limited

to a specific quantity per shift.

• A portion of the waste natural rubber adhesive from the

coater is reused in subsequent product formulations.

• Evaporated carrier solvents are recovered and reused. The

vapor recovery system is being redesigned to improve its

efficiency.

• Waste film trimmings are pelletized and reused.

• Waste hot melt adhesive purged from equipment lines is sold

when possible.

• Waste release that becomes too thick for use is diluted and

reused.

Pollution Prevention Opportunities

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

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

the waste, and the waste management cost for each waste

stream identified are given in Table 1.

Table 2 shows the opportunity for pollution prevention that the

WMAC team recommended for the plant. The 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.

It should be noted that the economic savings of the opportunity

results from reduction in raw material and costs associated

with waste treatment and disposal. Other savings not quantifiable by this study include a wide variety of possible future

costs related to changing emissions standards, liability, and

employee health.
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Additional Recommendations

In addition to the opportunity recommended and analyzed by

the WMAC team, several other measures were considered.

These measures were not analyzed completely because of

insufficient data, implementation difficulty, or a projected lengthy

payback. Since these approaches to pollution prevention may,

however, increase in attractiveness with changing conditions in

the plant, they were brought to the plant’s attention for future

consideration.

• Reformulate the natural adhesive, primer, and release coat

using a single solvent as the carrier for each.

• Develop a program to test the release periodically for parameters that can determine its effective life. Discontinue the

practice of arbitrarily replacing the release.

• Install a solvent recovery unit for processing waste toluene

onsite.

• Monitor the development and application of the Braytoncycle heat pump for use in recovering solvent vapors.

This research brief summarizes a part of the work done under

Cooperative Agreement No. CR-819557 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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Large Film

Rolls

Release Application

Primer Application

Natural Rubber

Adhesive Application

Smaller Rolls

to Slitters

Slitting

Inspection

Packaging

Acrylic

Adhesive

Application

Release

Application

Hot-Melt

Adhesive

Application

Slitting

Stretching

Trimming

Extrusion

Polypropylene

Pellets

Finished Tape Rolls

to Customers

Figure 1. Abbreviated process flow diagram for pressure-sensitive adhesive tape production.
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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/yr) Management Cost

Wastewater and pigment Coater for water-based acrylic tape Shipped offsite; incorporated into 89,130 $8,420

cement and buried

Waste natural rubber adhesive Coater for natural rubber tape Collected; reused onsite 128,270 12,9001

Waste natural rubber adhesive Coater for natural rubber tape Shipped offsite; incinerated 63,980 77,4101

Waste film Coater for natural rubber tape Shipped offsite; incinerated 27,420 58,3301

Waste primer Coater for natural rubber tape Shipped offsite; recycled and/or incinerated 9,740 5,460

Waste release Coater for natural rubber tape Diluted; reused onsite 1,320 02

Waste hot-melt adhesive Coater for hot melt adhesive Sold when possible; if not sold, disposed 26,670 02

of as nonhazardous waste

Waste release Coater for hot melt adhesive Diluted; reused onsite 6,960 02

Waste natural rubber adhesive Equipment maintenance Shipped offsite; incinerated 1,320 1,7201

Waste release Equipment maintenance Shipped offsite 480 270

Waste release Equipment maintenance Diluted; reused onsite 18,550 02

Used hydraulic oil Equipment maintenance Shipped offsite to be used as boiler fuel 2,960 40

Waste natural rubber Mixing of adhesive Shipped offsite; incinerated 9,770 12,7601

Waste paint Painting of equipment and building Shipped offsite; incinerated 410 200

1Includes lost raw material value

2No cost reported by plant.

Table 2. Summary of Recommended Pollution Prevention Opportunity

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Reduced Quantity (lb/yr) Per Cent Savings Cost Payback (yr)

Redesign the adhesive applicator on Waste natural rubber 57,700 90 $122,250 $125,000 1.0

the coater for natural rubber adhesive. adhesive (not reused)

Replace the reservoir applicator with Waste film 24,700 90

an extrusion applicator. Waste generated during line shutdowns will be reduced significantly.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/023