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PCT Engineered Comparison of UV and EB Technology for Printing and Packaging Applications User Manual

Comparison of uv and eb technology for printing, And packaging applications, Tech n ical p ape r

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SEPTEMBER/OCTOBER 2008 RADTECH REPORT 27

Tech

n

ical P

ape

r

Comparison of UV and EB
Technology for Printing

and Packaging Applications

By Stephen C. Lapin

U

V/EB curing technology for

inks, coatings and laminating

adhesives has become well

established in certain segments of the

packaging industry—including folding

cartons, labels and multiwall bags.

There is also growing interest in UV/EB

technology for flexible packaging.

1

The

growth in UV/EB applications is due, in

part, from the inherent advantages over

solvent- and water-based materials.

The solvent in conventional inks,

coatings and adhesives functions

simply as the “carrier” for the “solids”

high energy required to remove water

from the solids portion of the formula.

This high-energy requirement for water

is illustrated by comparing the heat of

vaporization to some common solvents

2

:

water = 540 calories/gram

toluene = 88

heptane = 76

The generation of energy needed to

operate the driers to remove water

results in significant CO

2

emissions. In

addition, most water-based materials

do contain some solvents to aid the

formation of the polymer film upon

drying the ink, coating or adhesive. Also,

in many cases, water-based materials do

not have the resistance or appearance

properties to match higher performance

solvent- or UV/EB-based materials.

In spite of the clear advantages of

UV/EB technology over solvent and

water-based technology, there is often

some confusion as to whether UV or

EB is a better choice. A clear

understanding of the differences

between UV and EB can facilitate a

selection of which technology is best

suited to the end-use application.

UV and EB Energy
Considerations

There are some fundamental

differences between UV and EB energy

that provide the foundation for

understanding the technologies. The

smallest “bit” of UV energy is the

photon that is known to have both

particle and wave-like characteristics.

A clear understanding of the differences between

UV and EB can facilitate a selection of which

technology is best suited to the end-use application.

portion of the material. In most cases,

solvent emissions are handled by

thermal oxidation which produces

greenhouse gas (CO

2

). Solvents are

highly refined materials derived from

fossil hydrocarbon sources. It is quite

wasteful to use such a high-value

material for such a low-value temporary

function. Solvent-based materials are

old technology that is clearly out of

step with a sustainable future.

At first glance, water-based inks,

coatings and adhesives would appear

to be an excellent choice from an

environmental perspective. Water is a

relatively plentiful, low-cost and

environmentally friendly carrier. The

main disadvantage with water is the

º