FTA (изд-во). Flexography: Principles And Practices. Vol.1-6

Подождите немного. Документ загружается.

much stronger and stiffer corrugated boards.

The terms “inside liner” and “outside liner”

refer to the orientation of the liner with

respect to the shipping container. Some-

times, a better-quality liner is used on the out-

side surface for improved printing. Today

there are perhaps as many as 50 different

specifications for the outside printing sur-

face of the facing liner, from plain kraft to

high-holdout bleached and coated material.

One of the major concerns of the box man-

ufacturer, which also has a major effect on

the printer, is the type and integrity of the

board construction. Presuming that the bond

is made properly between the medium and

the liner, the most important factor in the

value of the corrugated container is the

integrity of the flutes. The flutes provide the

necessary flat crush strength of the box; they

provide the resiliency that absorbs the

shocks of shipping and handling. It is the flut-

ing concept that created the corrugated box

industry. The flutes provide the protection to

the contents of the corrugated container. If

the flutes fail to support their proper load,

the box fails to meet its primary function –

protection.

The A-flute has the highest flute height,

with a greater space between each flute.

Corrugated board constructed with the A-

flute is susceptible to crushing and is not

suitable for heavier products. The other

flutes have more and smaller flutes per foot

Table 22). This construction enables the cor-

rugated packages to withstand a crushing

force and still protect their contents. Smaller

flutes, such as F, N and micro flutes, have

been developed for the small-container mar-

ket, and provide a much smoother printing

surface.

DEFECTS

There are many different defects that can

be generated during the corrugating process.

These defects can affect the production rate

of the corrugated boxes at the flexo-folder-

gluer, as well as the print quality of boxes

being produced. A good flexo post-print

operator must inspect the corrugated board

as it comes to the machine, and must be able

to recognize defects before feeding them into

the flexo unit. This inspection eliminates

waste and saves press down time.

Most of the combined board defects fall

into these major areas:

• flute integrity;

• caliper;

• washboarding;

• blank size; and

• warped board.

Flute Integrity

A major defect of corrugated board, and

one that all operators should be aware of, is

flute integrity. The construction of the flute

and the bonding to the linerboard play a large

role in the production of quality boxes. Some

of the flute problems created at the corruga-

tor include leaning, uneven heights, and

crushed flutes, which affect board caliper

(Figure

SUBSTRATES 143

Table 22

FLUTES/ HEIGHT OF

FLUTE DESIGN LINEAR FOOT FLUTE

K 24.6 0.260

A - Standard 35.4 0.177

A - Optional 37.7 0.158

C - Standard 39.4 0.142

C - Optional 38.6 0.140

B - Standard 46.9 0.098

B - Optional 46.9 0.097

E - Macro 84.7 0.053

E - Micro 89.9 0.044

F 128.1 0.030

N - Standard 170.0 0.020

N - Optional 140.0 0.020

TYPICAL FLUTE SPECIFICATIONS

144 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Leaning flutes fail to provide sufficient flat

crush. Insufficient flute heights cause prob-

lems with bonding, or if they do bond, they

cause low spots in the board, places where

printing plates cannot touch without crush-

ing other flutes.

Crushed flutes are flutes that have been

smashed, resulting in the failure of the box

to hold its contents or to stack properly.

Crushing also results in low caliper and

missing print areas.

Caliper

Caliper is the measured thickness of the

board. The caliper differs with a change of

flute size and with the grade of paperboard

used in construction of the board. The flexo

operator must always check the board cali-

per of each order. Blanks have to fit properly

through the feed gates (not too tightly, or so

loosely that more than one blank can pass

through at one time). As the blanks proceed

through the machine, they are pulled by rolls

and pull bands that have high coefficients of

friction. It is necessary for the rolls and pull

bands to apply a slight pressure on the blank

so that they maintain control of the blank as

it is pulled through the machine. If there is

too little pressure applied to them, the rolls

and pull bands lose control of the blanks,

which results in skewed or misfed blanks

into the next section of the machine. When

the board goes into the printing section,

excessive pressure on the board embosses

the printing, making it unsightly and, at the

same time, crushing the flutes.

Washboarding

Washboarding is a physical fault in which

the liners, instead of forming a flat, smooth

outer surface, partly follow the contours of

the fluted medium to produce alternate

ridges and valleys (Figure

). The lighter

the weight of liner used, the more likely that

washboarding will be present.

Washboarding makes printing very diffi-

cult because of the uneven surface. Wash-

boarding makes it necessary to increase

printing-plate impression, which crushes the

board with resulting loss of caliper, flat

crush and print quality.

Blank Size

Board length is very important for reducing

waste, eliminating problems in the flexo-fold-

er-gluer, in die cutting, and for box-making

accuracy. Boards that are cut too long at the

corrugator result in waste. The waste comes

from the scrap that is trimmed off at the flexo-

folder-gluer or die cutting machines. Boards

that are too short will skew in the flexo unit,

causing jams in the machine. Short boards in

a flexo-folder-gluer do not form good boxes

because the glue tab will not overlap the side

panel properly, thus the tab will not hold and

the box will not form properly.

There are two causes of short boards. The

obvious one is that the board is cut too short

at the corrugator. The other is improper cur-

ing. When a board comes off the corrugator,

it is still warm and contains moisture, feeling

much like a loaf of bread that just came out

of the oven. A hot board also affects ink

transfer and drying in the printing units. It is

better to wait and let the boards “cure” in the

“Work in Progress” area before using them.

Waiting allows the boards to normalize and

The construction of the

flute and its bond to the

linerboard plays a large

role in the production of

quality boxes. Some

of the flute problems

created at the corrugator

include leaning, uneven

heights and crushed

flutes, which affect

board caliper.

Washboarding is a

physical fault in which

the liners, instead of

forming a flat, smooth

outer surface, partly fol-

low the contours of the

fluted medium to pro-

duce alternate ridges

and valleys

Caliper

Uneven Flute Height

Leaning

Normal

cool down to room temperature. As the

warm, moist boards cool, they tend to shrink.

Warped Board

Warped board (Figure

) in corrugated

postprinting, variability of the substrate is

the greatest of any industry. As described

earlier, double- or even triple-wall combina-

tions of flutes can be manufactured. The out-

ermost liner (the double-backer liner) is the

one that receives the printing. Therefore,

depending on the flute profile chosen in post-

printing (single-wall, double-wall, etc.), the

printer is compelled to compromise to

account for caliper variations, wash board-

ing, surface pH variation in the area where

the corrugator starch is applied and exces-

sive warp on sometimes incredibly stiff

sheets.

Since there are no exact specifications as

to the composition of the printing liner other

than mechanical strength characteristics, the

printing surface can be extremely absorbent

or high-holdout, or it can be extremely hard

or very soft. Since the fluting material also

follows rules that have nothing to do with

printability of the liners it supports, post-

printing presents many challenges.

So, what is the best corrugated substrate to

print on flexographically? There are many

desirable quality considerations, some of

which are:

• caliper of print liner a minimum #38

(38 lb./1,000 ft.

);

• smoothness of the finish (highly calen-

dered);

• medium clay-coating or solid-bleached

sulfite;

• absence of loose fibers;

• medium to smallest flute profile

(B down to N);

• good quality medium-minimum #24

(24 lbs./1,000 ft.

);

• flat sheets;

• caliper-correct sheets;

• no washboarding;

• consistency in hue and brightness;

SUBSTRATES 145

When corrugated liners

exhibit this “ridging”

effect, it becomes

necessary to compen-

sate for the uneven

surface by increasing

printing-plate impres-

sion. This crushes the

board, yielding other

unfavorable results:

loss of caliper and print

quality.

Variability of corrugated

substrates accounts for

different warpness.

Flat Corrugated Normal ("Up") Warp Reverse ("Down") Warp

End-To-End Warp "S" Warp Twist Warp

Warp Axis

Board Travel

146 FLEXOGRAPHY: PRINCIPLES & PRACTICES

The regular slotted

carton (RSC) is the

standard form of

shipping container with

top and bottom flaps

• dust-free sheets; and

• controlled moisture content.

The wish list of the printer could go on

and on, but the corrugated board and box

manufacturer has economical constraints

and even the preferences mentioned here

hardly ever exist together in a corrugated

plant. The quality-conscious postprinters of

today deserve a lot of credit for past and

current achievements.

BOX CONSTRUCTION

There are many different types and styles

of boxes as well as special construction dis-

plays produced in the corrugated postprint

industry. These box constructions may be

broken down into two major categories:

slotted cartons, lids and trays, which are

generally produced on an in-line flexo-fold-

er-gluing machine; and special folded boxes

and displays which require die cutting.

Slotted Cartons

The regular slotted carton (RSC) is the

standard form of shipping container with top

and bottom flaps. Figure

shows how the

leading and trailing slots have been cut into

the blank sheet to form the box flaps. End-

and vertical-scores are impressed into the

blank to assist in folding the flaps. In this

instance, the lead and trail scores are

impressed into the blank at the corrugator and

the vertical scores are impressed on the flexo-

folder-gluer. The glue tab is cut into the blank

for attaching the end panel to the side panel.

Other types of containers produced on the

flexo-folder-gluer include the half-slotted

container (HSC) and trays, which are pro-

duced two at a time. The majority of flexo-

folder-gluer machines have limited die-cut-

ting capabilities.

Die-cut Blanks and Containers

Corrugated materials that require die

cutting are generally produced on a sheet-fed

corrugated flexo printer equipped with either

a rotary or a platen die-cutting station. The

die-cut station may be in-line or off-line with

the printing. Off-line die cutting is preferred

when printing high quality multicolor graph-

ics and halftone process screens.

End panel

Glue Tab

Side Panel

Lead Score

Body of Box

Side Panel

Trail Score

Slot

Flaps

Vertical Score

Glue Tab

End Panel

SUBSTRATES 147

Laminates

he primary label is important in

packaging decoration because:

it differentiates the product

from its competitors, creates

perceived value to the consumer

and fights for attention on the

shelf at the store. Pressure-sensitive coated

films and paper serve this growing market.

PRESSURE-SENSITIVE

COATED FILMS

The packaging-decoration market is a $3-

billion market that continues to grow. Within

this market, pressure-sensitive film is the

fastest growing segment. In 1996, heat-trans-

fer technology accounted for less than 5% of

the packaging-decoration market, as did

shrink-sleeve and in-mold labeling. Pressure-

sensitive represented 40% of the market, while

wet glue made up the remaining 60%

Pressure-sensitive film for packaging dec-

oration improves the overall aesthetics and

durability of the labeled container. It looks

as good on the day the finished product is

used, as on the day it was purchased. It is

also a response to the advances made in

printing and application technologies. It con-

tributes to lower total applied cost of the

package. In beverage applications, it also fits

in with environmental concerns. The label

can be made of the same material as the bot-

tle, so that the entire package is recyclable.

The outlook for pressure-sensitive prima-

ry labels in the personal care category is for

medium growth. The market has seen an

emergence of commodity products and a

need for high performance coupled with low

cost. Growth opportunities lie in secondary

labeling, package reduction, couponing and

private brands.

The outlook for the household chemical

market is higher than in personal care, with

an anticipated growth in the foreign mar-

kets. Opportunities lie in the thinking that

clear containers are good, and in the push

for recycling/refilling.

The food and beverage market continues

to see growing use of pressure-sensitive films

because this is a relatively mature industry.

Growth is in the glass packaging/clear con-

tainers, private brands and product line

extensions.

The pharmaceutical market is currently

growing slowly, but will increase due to the

aging population. Opportunities will be

found in tamper-evident packaging, the need

for more information to be provided with the

product, and in shelf competition.

FACESTOCKS

Currently, 90% of the films used in packag-

ing decoration are vinyl, polyester, polysty-

rene, polyethylene and polypropylene. Films

are available either corona-treated, print-

treated or top-coated to give the printer ease

in ink selection regardless of the type of film.

Polyvinyl Chloride (Vinyl)

Two different processes are used to manu-

facture vinyl films for pressure-sensitive

applications: calendering and casting. Both

processes use the same basic raw materials:

polyvinyl chloride resin, plasticizer (for flex-

ibility), UV stabilizers (for outdoor use),

antioxidants (for film processing), and col-

orants. It is the additives that are migratory

148 FLEXOGRAPHY: PRINCIPLES & PRACTICES

and will bloom to the surface and can make

printing difficult. Shelf life of the vinyl is

dependent upon the quality of these addi-

tives, and storage conditions.

Calendered Vinyl has an outdoor life of one to

five years, and is typically available in thick-

nesses of 3 to 10 mils. Vinyl has high tear resis-

tance, good dimensional stability, and is a

squeezable film. Unfortunately, it is prone to

label shrinkage (especially if conditions

approach the temperature at which it was cal-

endered). It is fairly expensive, and has low

stiffness, which can cause dispensing issues.

Because of the way it is processed, vinyl has a

high tensile strength and lower elongation in

the machine direction than in the transverse

direction. This attribute can manifest itself in

end-use applications, or on-press, especially if

exposed to high temperatures.

Cast Vinyl has an outdoor life of five to seven

years, and is available only in thicknesses of

1.5 to 3.0 mils. Its biggest advantage over cal-

endered vinyl is its ability to conform over

rivets, making it ideal for large signage appli-

cations. Unfortunately, it is more expensive

than calendered vinyl.

Nontop-coated vinyl can be printed only

using solvent-based and UV-curable inks.

Screen inks typically have the heaviest ink

laydowns, and therefore contain the highest

amount of solvents or monomers. In order to

be printed flexographically, as well as via let-

terpress and offset, vinyl has to be top-coated.

The topcoat is a low-solids coating applied to

the film, analogous to a primer coat.

Polyester

Polyester is manufactured with polyethyl-

ene terephthalate resin (to impart toughness

to the film) and colorants, such as titanium

dioxide. It is manufactured by the cast ten-

tering method, which gives the film its biax-

ial orientation as well as its high tensile

strength in both the machine and the trans-

verse direction.

Clear polyester has an outdoor life of two

to three years, and is available in thicknesses

ranging from 1.5 to 7.0 mils. Polyester is a

very stiff film, which makes it easy to dis-

pense, is dimensionally stable (because of the

cast/tentering) and has high solvent and tem-

perature resistance. It is not a conformable

film (cannot be used in squeezable applica-

tions) and is very expensive.

The solvent resistance, which permits

polyester to be utilized in harsh environ-

ments, makes it very difficult to print. Non-

topcoated polyester is printable only with

solvent based inks. If it is topcoated, it can

be printed with water-based and UV-curable

inks as well.

Polystyrene

Polystyrene is produced with crystalline

polystyrene resin or rubber-modified poly-

styrene (to give it some flexibility), and is

available as clear, clear matte, white matte,

or metallized. It is usually produced in the

same way as polyester and consequently can

react similarly in its end use or on press.

Polystyrene is not intended for outdoor

use, and is available in the 2- to 10-mil thick-

ness range. It is a very economical film that

can be competitive with paper. Its inherent

stiffness makes it easy to die cut and dis-

pense. Unfortunately, it is solvent-sensitive,

and has low-heat and tear-resistance.

Without some type of surface modifica-

tion, be it corona treatment or topcoat, it is

usually printed only with solvent-based ink

systems. After the surface is modified, it can

be printed with water-based and UV-curable

systems as well.

Polyethylene

Polyethylene historically has been manu-

factured by the blown-bubble method. It has

a limited outdoor life and is available in a

wide range of colors, typically in thicknesses

of 2 to 4 mils. It has high tear resistance, a

smooth surface, and is very conformable.

The clarity is poor and it can be difficult to

die cut and dispense.

Without surface treatment, polyethylene

has a surface energy of approximately 32

dynes which make it difficult for inks to wet

out on, let alone adhere to. After applying a

topcoat, it is printable via screen, flexo, off-

set and letterpress.

Polypropylene

The most talked about film in the poly-

olefin family is biaxially-oriented poly-

propylene (BOPP). It is an indoor film typi-

cally manufactured at 2-mil thickness. It has

excellent optical clarity and high solvent

resistance, but can be difficult to die cut.

Considerable time has been spent in devel-

oping topcoats for polypropylene that can

survive end-use requirements, including pas-

teurization, as well as compatibility with UV

flexo inks.

PRESSURE-SENSITIVE

ADHESIVE SYSTEMS

Adhesives must have the proper balance

of tack, peel and shear properties necessary

for the intended end use. Tack is a measure

of how quickly an adhesive wets and estab-

lishes surface contact to the material being

bonded. Peel is a measure of the force

required to break the bond between the

adhesive and the surface to which it is

applied. Shear is the measure of the adhe-

sive's inner cohesive strength.

The ideal adhesive will offer short-term

repositionability (up to 24 hours after appli-

cation), moderate term removability (24–72

hours) and long-term permanency (beyond

72 hours). This allows for rework opportuni-

ties either on-line or off-line in the event of

misapplied labels. This is a lot to ask of an

adhesive system considering the variety of

resins used in bottle manufacturing, their

respective surface energies, and the tear

resistance of the films previously discussed.

High-speed automatic label application

requires moderate to high initial tack to pre-

vent labels from falling off during the appli-

cation cycle. Moderate-to-high shear proper-

ties are important for squeezable containers

to prevent tunneling of the label during

deformation of the labeled container.

For the increasingly popular no-label look,

the adhesive must have water-like clarity (the

liner selection is also a contributor in this

application). For many applications, the

adhesive must also be resistant to water and

humidity. In newer applications, the same

adhesive may need to be able to tolerate wide

temperature requirements from pasteuriza-

tion temperature to water immersions.

Most high-performance adhesives for

pressure-sensitive labeling use solvent-

based acrylic chemistry. Recent advances in

adhesive technology, plus environmental

concerns, allow for the successful use of

high-performance emulsion acrylics in many

applications. Rubber-based adhesives find

their place with opaque label materials and

with low-surface energy containers.

Choosing a Release Liner

A release liner has four basic functions:

• carry other label components through

the converting process;

• protect the adhesive;

• provide a die cutting base; and

• act as the label dispensing system.

Historically, the choices for release liners

were extremely limited. Bleached, calen-

dered kraft papers in the 40# to 50# basis

weight range with silicone coating on one

side were practically universal in use. With

demand for a stronger, more tear-resistant

liner, plus the increase in no-label look appli-

cations, a 150-gauge polyester liner was

developed. Today, options include biaxially

oriented polypropylene and extrusion-coat-

ed natural kraft paper.

SUBSTRATES 149

150 FLEXOGRAPHY: PRINCIPLES & PRACTICES

PRESSURE-SENSITIVE PAPER

Paper-based, pressure-sensitive laminates

are the second most popular substrate used

in printing. After label die-cutting tools

appeared in the mid-1930s, the category

began to expand from simple price stickers

to sophisticated, converted products that

have met the decorating and marking needs

of practically all segments of the industrial,

commercial, consumer and medical markets.

Better paper stocks with outstanding flex-

ographic printing capabilities, a broad range

of adhesives to adhere to a wide variety of

materials and release liner technology for

high-speed converting and processing have

all helped make these materials popular.

Among the markets that prefer them are

consumer product primary labels, inventory

control and order-picking systems, printed

stickers, coupon promotional labels and

many other familiar devices.

From about $500 million a decade ago, the

value of converted pressure-sensitive papers

sold today exceeds $1.6 billion. They are

produced in roll form and supplied to flexo

printers sheeted, in uncut master rolls or in

specified roll widths. Master rolls can be up

to 78" wide, and selling price is based on cost

per msi (thousand square inches).

Pressure-sensitive paper substrates are

limited to 78" in roll width, up to 15,000' in

roll length, with core diameters of 3" to 6".

Gloss, semi-gloss and matte finishes of tag

stocks, fluorescent, colored papers, in addi-

tion to latex impregnated, laminated and

solid foils, metallized papers and thermal-

sensitive imaging stocks are all suitable for

flexographic printing.

Physical Properties

Substrate thickness is usually measured in

mils and, depending on the material, can

range from 2.5 mils to 10 mils. Basis weight

is calculated in pounds per ream (25" x 38",

500 sheets) and varies by material type from

30 lbs. to 150 lbs. per ream.

Flexibility and gloss are the strength of

these substrates, with a facestock’s luster

ranging from matte to high gloss. Smooth-

ness can have a big impact on print quality

with smoother sheets usually providing more

uniform ink coverage. For applications that

call for computer imprinting and smudge

resistance, a rougher, uncoated sheet, or one

with smudgeproof coating is best. Low-sur-

face-strength facestocks are most efficient

where label destructibility is needed, but the

substrate must be strong enough to with-

stand converting. When choosing a faces-

tock, the label shape, web width, converting

equipment, pressure-sensitive adhesives and

release liners should be considered.

Standard paper stocks can’t take much

exposure to moisture without a clear coating

of varnish or over-laminate. Of the paper

facestocks, those which are latex and resin

impregnated have the best moisture resis-

tance. Generally, uncoated facestocks or

those with smudge-proof coatings are more

suitable for computer applications. The

degree of smudge resistance can be influ-

enced by the type of imaging method, the

printer and the type of ink ribbon or toner

required.

Printing and Converting

Characteristics

The paper facestocks used in pressure-sen-

sitive work have many of the printing char-

acteristics of other paper substrates.

Because the whole pressure-sensitive con-

struction, including facestocks, adhesive and

release liner, is handled by flexo equipment,

it is important to look at how each compo-

nent relates to the final converting step of die

cutting and stripping. As mentioned before,

the facestock has a number of traits that

determine the quality of printing and con-

tribute to the performance of the whole con-

struction. Key properties, which determine

the ability to die cut and strip any material,

include tensile strength, tear and elongation.

SUBSTRATES 151

The facestock’s coating is extremely

important to the printer because it dictates

ink receptivity, holdout and character defini-

tion. Coatings can be used to change proper-

ties such as opacity and gloss, and can have

a direct effect on die life. If coatings are abra-

sive, dies wear out faster. Some papers are

filled with abrasive materials that can affect

paper strength. For example, a true 40# to

45# basis weight sheet of paper can be turned

into a 60# glossy facestock by using a coat-

ing. In this case, the coating accounts for a

good deal of the basis weight. The bottom

line is the direct effect on internal properties,

die cutting and stripping.

The release liner is just as important in

label production as printing quality and die

performance. Most liners are made from a

bleached, supercalendered kraft paper. Other

popular materials are unbleached brown

kraft and film liners ranging from extruded

films to coextruded combinations. All liners

are designed to withstand die cutting and

automatic label dispensing.

Along with internal strength, two other

critical features of the release liner are need-

ed for the successful manufacture of printed

labels. Density is needed to withstand the

die strike and to maintain the proper holdout

of the silicone-release coating. Insufficient

holdout can cause release problems where

the liner and facestock do not readily sepa-

rate. This condition can hinder diecutting

and stripping. Another vital factor is liner

thickness. Uniform thickness ensures that

the die will make a clean cut through the

facestock and adhesive coating without frac-

turing the release coating or cutting into the

release liner.

Rotary dies are tooled to the following liner

thicknesses: 40# liner is usually 2.4 mils thick

with a given tolerance of 0.3 mil; 50# liner is

normally 3.5 mils thick with the same toler-

ance. The release coating is critical to pres-

sure-sensitive construction and relates direct-

ly to converting performance. The character-

istics of silicone-release coatings are deter-

mined by a complicated chemistry formulat-

ed to provide a specific range of release that

is often dictated by the construction and the

application itself. These coatings are de-

signed to withstand normal die impact, but

can fracture under a die that has been

improperly made or adjusted. Fracturing the

liner with too deep a die cut will expose paper

fibers in the liner and allow the adhesive to

flow in. The result is a label partially bonded

to the liner.

Primers are sometimes used with faces-

tocks to prevent certain adhesives from

migrating through the paper and for sealing

the open pores of some papers to provide

better anchorage for the adhesive. Properly

applied primer coatings generally are not a

factor in printing or converting quality. A

number of adhesives are available for perma-

nent, removable, cold-temperature and spe-

cialty printed labels. These can be solvent-

based, emulsion or hot melt.

152 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Foils

Foil, a thin layer of

metal on top of a

substrate, is produced

in a vacuum chamber.

oils are produced using vacuum

metallizing. In this process, a thin

layer of metal, usually aluminum,

is placed on a substrate, typically

a flexible film or paper. This is

done in a vacuum chamber, usual-

ly by resistance-heated evaporation sources

(Figure

). This highly reflective coating is

used for the aesthetic and barrier traits the

aluminum can provide. Among the users for

these metallized materials are thermal insu-

A Payoff Reel

B Spreader Roller

C Tension Roller

D Bowed Roller

E Nip Roller

F Chilled Drum

G Idle Roller

H Capstan Roller

I Spreader Roller

J Tension Roller

K Spreader Roller

L Lay-on Roller

M Take-up Reel

lation, labels and decals, capacitors and a

variety of decorations. One of the largest sin-

gle markets is flexible packaging where shelf

appeal and barrier properties are important.

Ordinarily, metallizing machines are cylin-

drical vacuum chambers that can process

substrates up to 120" wide. Reel diameters

are as high as 40" (OD). Because the metal-

lizing process takes place in a vacuum

chamber, it happens one reel at a time and,

for economic reasons, as large a reel as pos-