Yam, Kit L. (ed.). The Wiley encyclopedia of packaging technology

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29. Nanotechwire.com. October 8, 2005. Available at http://

www.nanotechwire.com/news.asp?nid=2409&ntid=&pg=1.

Accessed Dec. 29, 2008.

30. nGimat, web information. Available at http://www.ngimat.-

com/barrier/anti_microb.html. Accessed December 22, 2008.

31. R. Lowry, Pira, Proﬁt Through Innovation, web information.

Available at http://proﬁtthroughinnovation.com/packaging/

antimicrobial-packaging.html. Accessed December 29, 2008.

32. R. Lowry, Pira, Proﬁt Through Innovation, web information.

Available at http://proﬁtthroughinnovation.com/company-

proﬁles/nano-materials-and-paper.html. Accessed December

29, 2008.

33. TopChim, web information. Available at http://www.topchim.-

com/?biopolymer. Accessed December 29, 2008.

34. A. ElAmin, Meatprocess.com, May 2, 2007. Available at http://

www.meatprocess.com/Financial/EU-funds-nano-packaging-

research. Accessed December 23, 2008.

35. Greenbox Systems, web information. Available at http://

www.greenboxsystems.com/index.htm. Accessed Dec. 29, 2008.

36. Nanotechnology Now, March 18, 2008. Available at http://

www.nanotech-now.com/news.cgi?story_id=28562. Accessed

December 29, 2008.

37. Small Times, June 14, 2004. Available at http://www.smallti-

mes.com/articles/stm_print_screen.cfm?ARTI-

CLE_ID=269497. Accessed December 29, 2008.

38. EcoSynthetix, web information. Available at http://www.eco-

synthetix.com/. Accessed December 30, 2008.

39. M. Taylor, Assuring the Safety of Nanomaterials in Food

Packaging: The Regulatory Process and Key Issues, Woodrow

Wilson International Center for Scholars, Washington, DC,

2008.

NETTING, PLASTIC

JIM OHLINGER

Tipper Tie-Net, West Chicago,

Illinois

INTRODUCTION

Today there are two popular manufacturing methods

to produce plastic netting: knitting and extrusion.

Both methods produce a tubular or sheeted netting pro-

duct in a wide variety of mesh sizes, diameters, widths,

and colors. Plastic netting is purchased as individual

pieces, in continuous rope form, or sheared onto cardboard

mandrels.

The primary materials used to produce plastic netting

are high-density polyethylene (HDPE) and polypropylene.

Ultraviolet inhibitors can be added to the resin to give the

netting extra durability in direct sunlight applications.

HDPE has a high elongation value and must undergo

the process of orientation to achieve its maximum tensile

strength. The process of orientation is when the material

is heated and then stretched to the point just before

breakage. This process also keeps the netting from droop-

ing when exposed to heat applications. The melt index of

HDPE is 2081F. Polypropylene has a high melt index

(3251F), and it is used when temperature requirements

exceed 2081F. Polypropylene tensile strength is almost

twice that of HDPE with the equivalent weight ratio.

With the heat and strength attributes, polypropylene

netting is widely used in the meat–poultry industry.

The process of extruding plastic netting was invented

in the mid-1950s. Extruded netting is produced through

counterrotating dies. As the inner and outer die rotate,

small strands of molten plastic overlap each other, bond-

ing themselves together where they overlap. The extruded

plastic is then cooled by water; this material is called a

cast. The next process is orientation. The cast is heated

and stretched to the point just before breakage. After the

cast is oriented and has become the ﬁnal product, the net

is transverse-wound onto large spools (1).

MANUFACTURE

The manufacturing process of knitted plastic netting

offers the most versatile and variety of netting products.

Knitting machines offer simple and sophisticated stitch

patterns. The ﬁrst knitting machine was invented by

Reverend William Lee, an Englishman, in 1589. The ﬁrst

power knitting machine was introduced in 1832, in Cohoe,

New York by Egberts and American (2). The knitting

process is complex and varies by different types of ma-

chinery. To manufacture plastic netting via knitting, the

plastic resin must be manufactured into yarn or tape. The

yarn is then put onto a creel, with several individual

packages consisting of a single thread, or beam, and

several threads wound onto a large spool. The basic

concept of knitting is to take the yarn or plastic tape

from the creel or beam, and thread the set of needle guides

in the knitter. A bed of latch hooks move up and down

(vertically) as the needle guides move right and left

(horizontally). The needle guides are directed by a pattern

chain that controls the different mesh patterns; hexagon,

diamond, or countless other conﬁgurations. Knitting al-

lows the manufacturer to choose the style and the mate-

rial to be used, allowing a multitude of products.

APPLICATIONS

Plastic netting is used in an array of applications. As a

ﬂexible material, it conforms to irregular products (toys,

houseware products, etc.). Netting provides an excellent

packaging forum as a decorative and protective overwrap.

It provides the necessary air circulation for products such

as plants (tropical and ﬂowering) and various types of

fruits and vegetables. Because of plastic netting’s ﬂexibil-

ity, it can be looped, making a convenient carrying handle

for the consumer (fresh or frozen whole turkey and ham

products). In the meat–poultry industry, netting is used as

a transportation vehicle. The meat and poultry items are

encased in the netting in the production area and then

hung on smoke racks ready to go into the smoke house.

The netting allows the meat and poultry products to

receive smoke for ﬂavoring and coloring during the

818 NETTING, PLASTIC

cooking process. The netting leaves an attractive pattern

on the products, giving them the ‘‘old world’’ look. The

netting can be left on the product as a marketing tool for

product identity.

Netting has a wide variety of uses in sheet form. It

can be used to wrap pallets as an alternative to stretch

wrap. The netting can be put up the same way as stretch

wrap, to utilize modern equipment and hand applicators

that are available. This is an important tool where venti-

lation or heat dissipation is needed (produce, bagged

mulch, ﬂowers, ﬂour, etc). Because of its exceptional

strength, netting can be used to wrap heavy loads such

as bricks. In sheet form, netting has an abundance of uses.

It makes a great fence for construction or snow applica-

tions. It can be used as a safety net in construction to catch

debris and increase the safety of workers. It is widely used

in the horticulture industry as shade cloth protecting

plants from the harsh sun. It is also used as bird net,

protecting fruit trees, berry bushes, and ﬁsh ponds from

predator birds.

By using the knitted process to manufacture plastic

netting, different-color strings or threads can be combined

to form a multicolored netted product. An example is

Candy-Cane (trademark) red and white netting used to

package Christmas trees (3). This netted package allows

the tree to be easily transported from the retail lot to the

consumer’s tree stand at home. Netting is also used by

Christmas-tree growers to compress the tree. This gives

the grower the ability to ship more trees, saving in

transportation cost. The netting also protects the tree

from damage, and it makes the tree much easier to handle.

This packaging process also applies to other types of trees

(white oak, maple, bamboo, etc.).

Knitted netting is soft, durable, and strong, making it

an ideal packaging medium. The produce industry, which

uses extruded netting primarily for consumer-sized

packages, is seeing a trend moving toward knitted netting.

Both styles of netting offer adequate ventilation needed

for fruits and vegetables to reduce spoilage. The soft

texture of knitted netting does not damage the delicate

produce skin and makes an eye-pleasing package. A draw

string can be automatically inserted during the knitting

process, making a convenient closing mechanism as well as

a carrying handle. Potato sacks are a good example of this

process.

Plastic netting is a valuable packaging tool. It is

resilient, strong, and ﬂexible. Netting can be frozen and

then heated, or vice versa, keeping its strength and

ﬂexibility. Plastic netting is very cost-effective compared

to other forms of packaging and is recyclable. The applica-

tions and areas of usage keep growing as creative minds

keep developing new and innovative ways to use plastic

netting.

Some manufactures are

Tipper Tie-Net, 390 Wegner Drive, West Chicago, IL

60185

Polly Net Inc., P.O. Box 27, Three Rivers, MA 01080

C&K Manufacturing, 28025 Ranney Parkway, Wes-

tlake, OH 44140

BIBLIOGRAPHY

1. J. Scoba, Polly Net Inc., P.O. Box 27, Three Rivers, MA 01080.

2. The World Book Encyclopedia, Field Enterprises Educational

Corporation, 1970, pp. 279–280.

3. ‘‘Candy Cane,’’ manufactured by Tipper Tie-Net, 390 Wegner

Drive, West Chicago, IL 60185.

Cited Publications

J. Ohlinger, ‘‘Netting, Plastic’’, in A. J. Brody and K. S. Marsh,

eds., 2nd ed., The Wiley Encyclopedia of Packaging Technol-

ogy, 1997, pp. 666–667.

NITRILE POLYMERS

PAUL R. LUND

JOSEPH P. M CCAUL

The BP Chemical Company,

Cleveland, Ohio

INTRODUCTION

Nitrile polymers are generally those that contain the

cyano (C:N) functional group, also called the nitrile

group. The commercial development of these materials

was due in large part to the 1957 discovery by BP

Chemicals of a low-cost one-step process for acrylonitrile

(AN) production (1). The pure nitrile polymer, polyacrylo-

nitrile (PAN), is 49% nitrile. It is an amorphous, trans-

parent polymer with a relatively low glass-transition

temperature (T

=871C) (see Polymer properties) that

provides an outstanding barrier to gas permeation and

exceptional resistance to a wide range of chemical re-

agents. Unfortunately, its combination of properties is not

of commercial value in the packaging industry. Its pri-

mary deﬁciency is that it is not melt processable. It

degrades at 4281F (2201C), which is below that required

for melt processing. To overcome this handicap, nitrile

polymers are produced using acrylonitrile (CH

= CHCN)

as the monomer with other comonomers that impart melt

processability. Through this copolymerization process, the

desirable properties can be retained and the undesirable

properties can be suppressed.

COPOLYMERS

Styrene–Acrylonitrile (SAN)

Typical SAN polymers are made using a 3:1 ratio, by

weight, of styrene to acrylonitrile. The copolymer has a

combination of properties that reﬂect the processability of

the styrene component and the chemical resistance of the

AN. Gas-barrier properties are low because of the relatively

low AN concentration. SAN is of relatively minor signiﬁ-

cance in packaging, used in applications where PS would

sufﬁce with an added measure of chemical resistance.

NITRILE POLYMERS 819

Acrylonitrile–Butadiene–Styrene (ABS)

ABS is a graft copolymer of SAN onto a polybutadiene

backbone. The SAN forms a matrix phase, whereas the

polybutadiene forms a discrete (dispersed) phase. A tough

impact-resistance thermoplastic is produced by using the

grafting mechanism to compatibilize the two phases.

Although the polybutadiene is an excellent impact modi-

ﬁer with low T

(D 851C), its refractive index is different

from the SAN matrix polymer. Therefore, in contrast to PS

(see Polystyrene), PAN, and SAN are not transparent.

ABS is a major commercial thermoplastic, but it is rarely

used in packaging because of its opacity, lack of gas-

barrier properties, and economics relative to other com-

modity resins. However, thermoformed ABS (see Thermo-

forming) has been used, for example, to produce

margarine tubs. This is an application in which PS would

sufﬁce if not for its limited resistance to stress cracking. A

wide range of SAN ratios is used to achieve properties of

value in nonpackaging applications.

Acrylic Multipolymers

Some acrylic multipolymers are produced using AN as a

comonomer with methyl methacrylate (MMA). Refractive

index matched rubber modiﬁers are incorporated to com-

bine toughness with transparency. These materials are

used in healthcare packaging (2) (see Medical packaging)

and in some food packaging applications. Because the AN

concentration is low, these materials do not have excep-

tional gas-barrier properties [18.7 cm

mil/100 in.

d atm

at 731F (23 1 C)].

High-Nitrile Resins (HNR)

As noted above, SAN is a styrene–acrylonitrile copolymer.

Its gas-barrier properties are limited, however, by the low

nitrile content. High-barrier melt-processable copolymers

can be produced by raising the nitrile content above 25%.

Over this threshold, copolymer properties begin to resem-

ble those of PAN, particularly with respect to gas barrier

and chemical resistance.

Acrylonitrile–Styrene Copolymers (ANS). High-nitrile co-

polymers can be produced by combining acrylonitrile and

styrene in a 70:30 ratio. This was the approach taken by

Monsanto Company (Lopac) and Borg-Warner (Cycopac)

during the 1960s and early 1970s in their development of

resins for carbonated-beverage packaging. Lopac’s compo-

sition is 100% copolymer of 70% acrylonitrile and 30%

styrene. Cycopac’s composition is 90% copolymer of 74%

acrylonitrile and 26% methyl acrylate plus 10% butadiene

rubber graft (3). As serious commercial development

began, toxicological problems with AN surfaced (4). The

FDA banned the use of HNR in beverage packaging

because of concern for potential AN-extraction from the

bottle into the beverage. Since beverages are a major

component of the diet, their treatment by FDA was most

severe. The FDA continued to permit the use of HNR for

direct and continuous nonbeverage-food-contact applica-

tions (5) with ﬁlling and storage temperatures less than

1501F (65.61C); but because the principal commercial

signiﬁcance of ANS polymers was in carbonated beverage

packaging, all commercial production of ANS polymers

was eventually discontinued.

In 1984, the FDA amended its position on HNR-bev-

erage applications (6). Monsanto Company had petitioned

on behalf of their ANS high nitrile resin for approval. As

described in their process patent (7), the bottle preform is

irradiated with an electron beam prior to blowing of the

bottle. Monsanto claimed that this process resulted in a

bottle that, because of the thermodynamics of the extrac-

tion process, would have essentially no extraction of AN by

the contained beverage. The FDA did not accept this

claim, but it did decide that the extraction would be below

the detection limit of 0.16 ppb. The agency ruled that AN

concentrations at or below this detection limit would be

considered acceptable, and it limited the residual AN

content of the ﬁnished container of 0.1 ppm. This concen-

tration is current (8).

Rubber-Modiﬁed, Acrylonitrile–Methacrylate Copolymers

(AN/MA). High barrier properties can also be achieved by

copolymerizing acrylonitrile and methacrylate in a 75:25

ratio onto a nitrile rubber backbone. This is the approach

taken by BP Chemicals in the production of Barex (regis-

tered trademark) resins. Barex’s composition is 90% copo-

lymer of 74% acrylonitrile and 26% sytrene plus 10%

butadiene rubber graft (3). This family of resins can be

processed on almost all conventional plastic processing

equipment including, but not limited to, injection, injec-

tion blow molding, injection stretch blow molding, extru-

sion, extrusion blow molding, extrusion stretch blow

molding, proﬁle extrusion, pipe extrusion, tubing extru-

sion, and thermoforming (see individual processing sec-

tions). Transparency is retained through the use of a

refractive-index-matched rubber modiﬁer.

The Barex family of resins are the only high-nitrile

resins in commercial production today and are in full

compliance with all applicable FDA regulations for direct

food contact and meets all the known requirements of a

USP Class VI plastic. Barex is now marketed by INEOS.

PROPERTIES

Among the commercial packaging polymers that have the

physical properties required for monolithic structures,

HNRs offer the greatest gas barrier [0.8 cm

mil/

100 in.

d atm or 3.0 cm

mm/m

d kPa] and chemical resis-

tance. Their gas-barrier properties (see Barrier polymers)

are surpassed only by EVOH (see Ethylene–vinyl alcohol)

and PVdC (see Vinylidene chloride copolymers), which are

used as components of multilayer structures (see Coex-

trusions for ﬂexible packaging; Coextrusions for semirigid

packaging). Because of the polarity that the nitrile group

imparts to the molecule, HNRs show an afﬁnity for water.

Water-vapor barrier is lower than that of the nonpolar

polyoleﬁns (e.g., polyethylene, polypropylene), but that

same polarity imparts resistance to nonpolar solvents.

The relatively high ﬂexural modulus (combined with the

lower speciﬁc gravity) means that for structures with

identical geometry, the HNR parts can be source-reduced

820 NITRILE POLYMERS

(down-gauged) and therefore designed with less material

for equivalent stiffness compared to the polyoleﬁns, PVC,

PET, PETG, and many other plastic polymers. A summary

of the properties of high-nitrile resins is shown in Table 1.

APPLICATIONS

HNRs are used in packaging in a variety of physical forms.

These include: ﬁlm, semirigid sheet, and injection-molded

(see Injection molding) and blow-molded containers. Blown

ﬁlm (see Extrusion) is used in polyoleﬁn-container struc-

tures to provide formability, chemical resistance, and gas

barrier. Spices , medical devices, and household chemical

products are example of such applications . Laminations

with polyoleﬁns and aluminum foil are used in applications

ranging from food packaging to oil-drilling core wraps (9).

These structures have exceptional barrier properties, as

well as sealability and chemical resistance. Indeed, their

use in sachet packaging is growing rapidly as individual

dose and unit packaging become more popular.

The semirigid sheet market for HNR is primarily meat

and cheese packaging in thermoformed (see Thermoform-

ing) blister packages. With its excellent gas barrier,

clarity, and rigidity, the HNRs are the premium packaging

material. Of increasing importance in semirigid applica-

tions, however, is disposable medical device packaging

(see Medical packaging). Here HNR can be sterilized by

either ethylene oxide (ETO) or gamma radiation and is

unaffected by plasticizers present in many devices, mak-

ing it ideal for many medical packaging applications. As a

result of its unique combination of properties, including

source reduction and superior thermoforming, usage has

been steadily increasing in this market area.

Blow-molding applications for HNR are dominated by

chemical resistance requirements. Injection blow molding

is the most widely used method for manufacturing small

containers—for example, bottles for correction ﬂuid, nail

enamel, and other cosmetics. Larger bottles are generally

extrusion blow-molded. Some important applications in-

clude: pesticides, herbicides and other agricultural chemi-

cals, fuel additives, and hard-to-hold household chemicals.

Extrusion stretch blow molding is gaining increasing

acceptance for bottles 16 oz (473 mL) or larger. The orienta-

tion achieved during stretching greatly increases the drop-

impact performance, and the walls can be relatively thin.

HNR has been coextruded with many different poly-

mers, but the polyoleﬁns have been of greatest commercial

signiﬁcance. Coextrusions are available in sheet, ﬁlm, and

bottle form. They typically gain gas barrier or chemical

resistance from the HNR and water vapor barrier and

economics from the polyoleﬁn. In structures with poly-

propylene, the heat-deﬂection temperature (HDT) of the

structure is increased by the higher HDT of the polypro-

pylene. This permits the use of HNR in high-temperature

environments such as microwave ovens.

The adhesive used to combine the layers in an HNR

coextrusion are typically styrene–isoprene or styrene–

butadiene block copolymers (see Multilayer ﬂexible packa-

ging). Scrap is reusable in the polyoleﬁn layer if the

nonoleﬁn percentage in that layer is well-dispersed and

of lower concentration than about 15%.

Chemical-resistant coextruded bottles containing

HNR are now being commercialized. HNR is the inner

contact layer enclosed by adhesive and polyoleﬁn, typi-

cally HDPE. Use of a three-layer structure limits the cost

and complexity of the machinery. It also places the sol-

vent-resistant polymer in contact with the chemicals. Five

layer or laminar structures (see Surface modiﬁcation;

Nylon) using other barrier resins place the polyoleﬁn in

direct contact with the aggressive contents of the con-

tainer. The three-layer structure also allows visual inspec-

tion of the barrier layer and maximizes the sealing area of

the barrier layer at the pinchoff of the bottle. HNR-

coextruded containers offer high performance with eco-

nomics superior to the other packaging alternatives (10).

Thermoplastic coextruded ﬁlms of 5–7 layers have been

reported (11).

Alloying and blending also offer other unique proper-

ties that can be imparted to the base resins, typically

polyoleﬁns. Here they can be used to reduce ESCR as well

as provide increased ﬂexural modulus (stiffness) to poly-

oleﬁnic resins (12).

The Barex family of resins offers a unique combination

of properties to the packaging industry. Barex resins

protect products from oxidation and are inert and resis-

tant to chemicals. They meet United States and European

regulations and, thus are available for a range of products,

They eliminate the need for a separate heat-seal layer and

are good against strong ingredients. As bottles, they keep

fragrances and ﬂavors in place. The following are applica-

tions of Barex (13).

Table 1. Properties of High Nitrile Resins

Property ASTM Test Units Barex 210 Resin Barex 218 Resin

Speciﬁc gravity D1505 1.15 1.11

Yield in.

/lb at 1 mil 24,080 24,950

Brabender torque meter-grams 950 1050

Notched Izod D256 ft-lb/in. 5.0 9.0

Flexural modulus D790 psi 490,000 400,000

permeability (731F, 100% RH) D3985 cm

-mil/100 in.

-24 h-atm 0.8 1.6

permeability (731F, 100% RH) D3985 cm

-mil/100 in.

-24 h-atm 1.2 1.6

permeability (731F, 100% RH) D3985 cm

-mil/100 in.

-24 h-atm 0.2 0.4

WVTR (1001F, 90% RH) F1249 g-mil/100 in.

-24 h-atm 5.0 7.5

Heat deﬂection temperature D648 1F 160 170

Heat seal temperature 1F 250–375 275–350

NITRILE POLYMERS 821

1. Medicinal Uses. Catheter trays, sachets, assay

trays, transdermic patches. These products are

sterilizable.

2. Personal Care. Cosmetic packs, perfume, mouth-

wash, nail enamel, and bath gel bottles.

3. Industrial Products. Among many nonpackaging

uses, criminal evidence bags and air fresheners.

4. Food and Beverages. Fruit juices, meats, and

confectionary.

BIBLIOGRAPHY

P. R. Lund and J. P. McCaul, ‘‘Nitrile Polymers’’ in A. J. Brody and

K. S. Marsh, eds., The Wiley Encyclopedia of Packaging

Technology, 2nd edition, Wiley, New York, 1997, pp. 669–672.

Cited Publications

1. J. D. Idol, U.S. Patent 2,904,580 (to BP Chemical, OH),

September 15, 1959.

2. J. M. Lasito, ‘‘Acrylic Multipolymers in Medical Packaging,’’

Proceedings of the TAPPI 71, 74, (1982).

3. P. Delassus, ‘‘Barrier Polymers’’ in Kirk-Othmer Encyclopedia

of Chemical Technology, Vol. 3, 5th edition, Wiley, Hoboken,

NJ, 2004, p. 386.

4. Report to the FDA by the Manufacturing Chemists Associa-

tion, January 14, 1977.

5. Federal Register 41 23,940. Title 21, Part 177.1480 (June 14,

1976).

6. Federal Register 49 36,637. Title 21, Part 177 (September 19,

1984).

7. M. Salome and S. Steingher, U.S. Patent 4,174,043 (to Mon-

santo), November 13, 1979.

8. 21CFR section 177.1041 (April 1, 2007).

9. P. K. Hunt and S. J. Waisala, U.S. Patent 4,505,161 (to BP

Chemical, OH), March 19, 1985.

10. J. P. McCaul, ‘‘The Economics of Coextrusion,’’ Proceedings of

the High Technology Plastic Container Conference, SPE,

November 11, 1985.

11. A. J. Lischefski, U.S. Patent 7,201,966 (to Curwood, Inc.),

April 10, 2007.

12. P. R. Lund and co-workers, ‘‘High Nitrile Polymer/Polyoleﬁn

Blends: A Low Cost, High Performance Alternative,’’ Proceed-

ings of the 1995 Annual Technical Conference, SPE, May 7–

11, 1995.

13. Barex, brochure, INEOS, www.INEOS.com. accessed Febru-

ary 2008.

NONWOVENS

J. ROBERT WAGNER

Philadelphia College of Textiles

and Science, Philadelphia,

Pennsylvania

INTRODUCTION

‘‘Nonwovens are fabric-like materials consisting of a con-

glomeration of ﬁbers that are bonded in some way or

other’’ (1). The total world wide sales of nonwovens in

2006 amounted to 19 billion dollars (5 109 t) (2). Non-

wovens may be sold by a yield or area basis, weight basis,

or product unit basis. Because of their unique properties

and high production rates, nonwovens offer a substan-

tially high performance/price ratio. However, in order to

appreciate the full range of products, properties, and end

uses of nonwovens, it is necessary to consider the ﬁbers,

the web-formation method, and the bonding methods used

to make them.

FIBERS

The primary ingredient of nonwovens are the ﬁbers used to

produce them. A ﬁber is substantially longer in length than

in diameter. In nonwovens, ﬁbers may vary in length from

1 mm to a continuous length. Short (1-mm) ﬁbers are used

in air-laid or wet-laid nonwovens. Spunbonded nonwovens

use continuous-length ﬁbers in their fabrication. The

length of the ﬁbers will affect both the uniformity of ﬁber

distribution and the strength of the nonwoven. Short ﬁbers

tend to give good ﬁber distribution, but longer ﬁbers tend to

produce greater strength. However, the ﬁber length actu-

ally utilized is dependent on the nonwoven-web-formation

process and the type of product being manufactured.

The diameter of the ﬁber affects the properties of the

nonwoven considerably. If it was desired to produce a soft

nonwoven facial wipe, baby wipe, or polishing cloth, a ﬁne

ﬁber should be used. If, on the other hand, it was desired

to produce a scrubbing pad of the required stiffness for a

frying pan, large-diameter ﬁbers should be used. The

latter would also give high incompressibility or resilience.

While many ﬁbers are perfectly round, some are trian-

gular, square, hollow, and of other shapes. In addition,

they may consist of one or more generic type of materials

in their makeup.

One major variable in nonwovens is the type of ﬁber

used in its construction. Virtually any ﬁber can be utilized

to make nonwovens. The principal natural ﬁbers found in

nonwovens are cotton, jute, and especially wood pulp. The

majority of spunbonded fabrics are based on either isotactic

polypropylene or polyester. Small quantities are made from

nylon 6,6 and an increasing tonnage from ﬂash spun high

density polyethylene (3). Because of their far-reaching

properties, the range of ﬁber types available offer great

latitude in the performance characteristics of the ﬁnal

nonwoven. Because of their high hydrophobic properties,

moisture-barrier properties are provided by polypropy-

lene, polyethylene, polyester, and polytetraﬂuoroethylene

(PTFE). High tensile strength may be obtained using

Kevlar aramid, Spectra oleﬁn, nylon, polyester, silk, and

glass. High-temperature resistance or low ﬂammability can

be obtained with carbon, glass, Kynol novoloid, Kevlar and

Nomex aramid, modacrylic, PBI, PTFE, ceramic, and me-

tallic ﬁbers. For composites, glass, carbon, Kevlar, and

Nomex aramid may be used. Chemical resistance may be

obtained with PTFE, glass, carbon, acrylic, oleﬁn, and some

metallic ﬁbers. It should be apparent, therefore, that proper

ﬁber selection is essential in order to ensure desirable end-

use performance characteristics of the nonwoven.

822 NONWOVENS

NONWOVEN WEB-MANUFACTURING METHODS

Nonwoven webs can be produced in four primary ways:

carding, air laying, wet laying, or spunbonding. Within

each one of these, the process and resulting product will

often vary considerably.

A carding machine feeds a mass of crimped ﬁbers,

opens, disentangles, and drafts the ﬁbers and then delivers

a thin wide web of uniformly distributed ﬁbers to some

form of delivery apron. The ﬁbers used to produce carded

nonwovens must have crimp and will usually have a ﬁber

length ranging between 34 and 152 mm.The ﬁbers exiting

the card tend to be aligned in the machine direction, and, if

used in this manner, the product is referred to as a

parallel-laid nonwoven. Often it is necessary to combine

the web from several carding machines to achieve the

desired nonwoven weight. A parallel-laid nonwoven

may be up to 11 times stronger in the machine direction

or ﬁber-oriented direction than it is in the cross-machine

direction. Also, the elongation in the machine direction is

substantially less than that found in the cross-machine

direction.

The web exiting the card may be laid back and forth

across a moving apron to produce what is known as a

cross-laid nonwoven. Because systems of ﬁbers cross each

other, the resulting nonwoven has more uniform strength

and elongation properties than found in parallel-laid

nonwovens.

Sometimes a parallel-laid web is combined with a cross-

laid web to produce what is termed a composite carded

nonwoven. The latter has the greatest uniformity in

strength and elongation properties of carded nonwovens.

In randomized carded nonwovens the card is similar to

that used for parallel laying, but the doffer roll is run in a

direction counter to that of the main cylinder at the point

of near-wire contact. Such a conﬁguration deparallelizes

the web, permitting more loft and greater uniformity of

strength and elongation in the machine direction and

cross direction.

Because of the great latitude in weight, thickness, ﬁber

orientation, strength, elongation, and ﬁbers utilized,

carded nonwovens have a vast number of product end-

use applications.

Air-laid nonwovens utilize ﬁbers having a length ran-

ging between 1 and 76 mm.The ﬁbers are ﬁrst opened,

then conveyed with an air stream against either a con-

densing cylinder or a screen to form the web. The product

produced tends to have an x, y, z-ﬁber orientation, and as a

result the webs are soft and lofty. Such a web is especially

useful in padding, insulation, ﬁltration, and wipes.

Wet-laid nonwovens utilize papermaking equipment

and technology. The ﬁber length ranges between 1 and

38 mm.The longer ﬁbers are either glass for rooﬁng shin-

gles and felt or carbon for composites. Shorter natural and

synthetic ﬁbers are used in tea bags, automotive air and

oil ﬁlters, coffee ﬁlters, bunting, hang tags, and compo-

sites. While ﬂat-tabled fourdrinier machines have been

used to make some nonwovens, the best machine for

producing wet-laid nonwovens is the inclined-wire ma-

chine since long ﬁbers are held in suspension in water at

the time of formation on the moving wire. Often multiple

headboxes are used to produce layered or stratiﬁed high-

efﬁciency air ﬁlters and other products.

Spunbonded and melt-blown nonwovens (see Figure 1)

are produced at the time the ﬁber is extruded from the

spinneretts. Spunbonded nonwovens are produced with

continuous ﬁlament ﬁbers that are drafted with either

multiple drafting rollers or high-velocity air used in

combination with a venture to achieve molecular ﬁber

orientation. Most spunbonded nonwovens are produced

with polypropylene or PET. However, polyethylene, polye-

ster, nylon, acrylic, and rayon are also used.

Melt-blown nonwovens are similar to spunbonded non-

wovens but instead use a spinnerette in which both the

polymer and hot air exit the spinnerette from different

oriﬁces simultaneously. The velocity of the air is sufﬁcient

to draft the polymer into very ﬁne discontinuous ﬁbers.

Melt-blown nonwovens are used for thermal insulation,

ﬁlters, padding, personal products, synthetic leather, and

other products.

Flash spinning is a radical departure from conven-

tional melt spinning. It begins with a 10–15% polymer

solution prepared by dissolving a solid polymer, such as

high-density polyethylene, with a suitable solvent. The

solution is pressurized and then permitted to expand

rapidly through a hole in a spinnerette. The solvent is

instantaneously ﬂashed off, leaving behind a three-dimen-

sional ﬁlm-ﬁbril network called a plexiﬁlament. These

plexiﬁlaments are substantially oriented and possess re-

latively high tenacities. Flash spinning is the most com-

plex and sophisticated method for manufacturing

spunbonded fabrics (3).

BONDING METHODS

There are four principal methods of bonding nonwovens:

chemical, mechanical, thermal, and inherent or self-bond-

ing. Chemical bonding may rely on binders, solvents, or

hydrophilic ﬁbers. Of these, binders are by far the most

important. Binders act like adhesive and include acrylic,

phenol, urea and melamine formaldehyde, poly(vinyl

Figure 1. Illustration of a polypropylene melt blown nonwoven

that is bonded using a heated pattern engraved calender roll.

Such a product is manufactured using a ﬁne oil-loving ﬁber and is

excellent for use as a shop towel or wipe.

NONWOVENS 823

acetate), styrene–butadiene rubber, vinyl acetate–ethylene,

poly(vinyl chloride), nitrile rubber, poly(vinyl alcohol), and

other lesser binders (4). Such binders vary considerably in

cost, properties, and performance characteristics.

Mechanical bonding includes needle punching, stitch-

through, and hydroentangling. Needle punching may use

either barbed or forked needles. Barbed needles interlock

the ﬁbers to provide mechanical strength to produce such

products as papermaker’s felts, blankets, geotextiles, syn-

thetic shoe leather, thermal lining, and automotive trunk

liners. The forked needles can produce velour and pat-

terned products for use as institutional and automotive

carpeting, and throwrugs.

Stitch through technology is a knitting-through process

that may be accomplished either with or without yarns to

stitch the nonwoven web together. The Mali and Arachne

machines are most common and produce products such as

carpets, upholstery, blankets, interlining, geotextiles, and

automotive products.

The hydrogenating process was invented by E. I.

DuPont and was ﬁrst referred to as the spunlace process.

It utilizes very ﬁne water jets to mechanically entangle

ﬁbrous webs.

Thermal bonding may include the use of thermoplastic

ﬁbers, yarns, powders, or ﬁlms. Often bicomponent ﬁbers

having differential melting temperatures in either a core-

and-sheath or a side-by-side conﬁguration may be utilized.

Bonding is facilitated by through-air heaters, and smooth

or patterned calender rolls.

Inherent or self-bonded nonwovens are bonded at the

time they are produced. This might include ﬁlm splitting,

blow extrusion, or static-charge extrusion. However, be-

cause of their limited properties and aesthetics, nonwo-

vens produced in this manner have limited uses.

Because of the ﬁber types available, the differences in

web-manufacturing processes possible, and the various

bonding methods, a cost-effective nonwoven product

can be produced with properties that will perform in

almost any application. However, adequate performance

characteristics are ensured only if a nonwoven incorpo-

rates the proper ﬁbers, web manufacturing process,

bonding method, and proper ﬁnishing and fabrication to

produce the ﬁnal product for the end-use application

desired.

PACKAGING APPLICATIONS

Packaging applications for spunbonded fabrics are for the

most part a specialty area in which paper products or

plastic ﬁlms do not adequately perform. One of the largest

packaging applications is high-performance envelopes.

The major use for spunlace fabrics is in medical pro-

ducts. In medical applications, great progress has been

made in the substitution of traditional reuseable woven

materials with higher-performing spunbondeds. Histori-

cally, ﬂash spunbonded polyethylene was the ﬁrst 100%

spunbonded to ﬁnd use in sterilzable packaging. Recently,

structures of spubonded–meltblown–spunbonded polypro-

pylene has gained acceptance in sterilizable wrap. Spun-

bonded fabrics with elastomeric properties are now

commercial. An economical approach using polypropylene

has recently become commercial and is used in medical

and hygienic applications (5).

Medical devices or trays of devices are often sterilized

after the nonsterile device is sealed in a package. A part of

the package, such as the lid, is made from ﬂashspun or

spunbonded–meltblown fabric because it possesses the

unique property of permitting the sterilizing gas of ethy-

lene oxide to pass through while remaining impenetrable

to bacteria (3).

BIBLIOGRAPHY

J. Robert Wagner, ‘‘Nonwovens,’’ in The Wiley Encyclopedia of

Packaging, 2nd edition, John Wiley & Sons, New York, 1997,

pp. 672–674.

Cited Publications

1. J. R. Wagner, Nonwoven Fabrics, Norristown, PA, 1982.

2. F. Hajduk, M. Blogoer, and T. Sasano, ‘‘Nonwovens,’’ Chemical

Economics Handbook, SRI Consulting, Menlo Park, CA, 2006.

3. R. L. Smorada, ‘‘Nonwoven Fabrics, Spunbonded’ in Kirk–

Othmer Encyclopedia of Chemical Technology, Vol. 20, John

Wiley & Sons, Hoboken, NJ, 2006.

4. J. R. Wagner, Nonwoven Notes, Norristown, PA, 1989.

5. J. Austin, (to BBA Nonwovens), U.S. Patent 6,225,243 May 1,

2001.

NUTRITION LABELING

JEAN STORLIE

Nutrition Labeling Solutions,

Ithaca, New York

KAREN HARE

Nutrition Services, Inc., Fort

Collins, Colorado

The regulatory issues associated with nutrition labeling of

food products are complex and extensive. Speciﬁc nutri-

tion information must be included on most food products

following particular design requirements. The regulations

also delineate what nonmandatory nutrition information

may be included and how it can be presented. Profes-

sionals involved in food processing, manufacturing, mar-

keting, and packaging need to be aware of nutrition

labeling regulations and understand how they affect food

packaging and marketing.

The purpose of this article is to provide a broad under-

standing of the nutrition-labeling regulations, explain

why they were developed, and describe some of the

approaches that may be used for developing nutrition

labels. A heavier emphasis will be placed on the issues

related to design and format, rather than those pertaining

to the content of the nutrition label. Because the regula-

tions are extensive and detailed, it is not possible in the

824 NUTRITION LABELING

scope of this article to cover all the issues necessary to

make this a ‘‘how to’’ reference. In order to apply the

regulatory requirements to speciﬁc packaging issues, it is

necessary to consult with regulatory source documents,

regulatory guidebooks, and/or legal or regulatory advisors.

HISTORY OF NUTRITION LABELING

Although the history of food labeling laws reach back as

far as 1906 with the Pure Food and Drug Act, it was not

until after World War II that consumer interest in and

need for nutrition information became evident (1). During

the war, food preparation shifted from the household to

large-scale food processing. The extended shipping times

for delivery of goods needed in war encouraged the devel-

opment of additives to extend shelf life. Wartime health

problems led to the recognition of the relationship be-

tween nutrition and diseases, spawning interest in nutri-

tion research and food labeling. Scientists recognized the

need for vitamins and minerals to prevent certain diseases

such as beriberi and pellagra.

By 1969, there was signiﬁcant public interest in the

relationship between diet and health. As a response to this

interest, President Nixon convened the White House

Conference on Food, Nutrition, and Health, addressing

malnutrition in America (2). He told Congress of the need

to ensure that the private food industry serves all Amer-

icans well and that people are educated in choosing proper

foods. As an outcome of this conference, along with Con-

gress’ effort to mandate nutrition labeling, the Food and

Drug Administration adopted a voluntary nutrition label-

ing program in 1973 that required the labeling of nutrition

information whenever a nutrient claim was made or a

product was fortiﬁed (3). At this time, the voluntary

nutrition label focused on key vitamins or minerals known

to cause deﬁciency disease.

Proponents of mandatory nutrition labeling were not

satisﬁed with the limitations of the voluntary program—

typically, only products with a good nutrition story

included nutrition labeling. Throughout the 1970s, man-

datory nutrition labeling continued to be addressed by

legislators—in particular, Senator George McGovern, who

chaired the Senate Select Committee on Nutrition and

Human Needs. This Committee investigated a number of

nutrition issues affecting Americans and was responsible

for issuing the U.S. Dietary Goals, the ﬁrst government

report setting prudent dietary guidelines for Americans

(4). In 1978, McGovern initiated a series of hearings to

explore nutrition labeling and information, where he is

quoted: ‘‘It appears from all I have heard and read to date

that the present labeling system is not useful or appro-

priate. Therefore we must determine what nutrition in-

formation the public wants and needs, and how best to

convey that information’’ (5). Although the hearing dis-

played the bipartisan nature of the issue, it took Congress

another 13 years before the Nutrition Labeling and Edu-

cation Act of 1990 (NLEA) was passed.

With the election of President Reagan in 1980, the

thrust to adopt mandatory nutrition-labeling legislation

came to an abrupt halt (1). Deregulation limited available

resources, causing FDA to focus on food-safety issues

and to deemphasize economic issues such as food labeling.

Despite this shift in legislative priorities, there were

major advances in science that documented the link

between nutrition and health. Several reports issued by

the federal government (6–8), in addition to reports re-

leased by nonproﬁt agencies, such as the American Cancer

Society (9) and the American Heart Association (10),

clearly showed the growing consensus about the relation-

ship between dietary imbalances and chronic diseases,

speciﬁcally the overconsumption of calories, fat, saturated

fat, cholesterol, and sodium and the underconsumption

of dietary ﬁber. As a result of extensive media coverage

of these ﬁndings, consumers began to demand healthier

food products and more information about the fat, choles-

terol, and ﬁber content of foods. Food manufacturers

responded by introducing nutrient-focused products—pro-

ducts lower in fat, cholesterol, and sodium and high in

ﬁber proliferated. Unfortunately, there were no guidelines

for deﬁning ‘‘low’’ or ‘‘high’’ or for labeling nutrients such

as dietary ﬁber, saturated fat, or cholesterol. As a result,

manufacturers’ efforts to produce and market such pro-

ducts without consistent rules led to incidence of abuse,

and consumer groups complained of food-labeling decep-

tions. By the end of the 1980s, the food industry, as well as

regulators and consumers, were frustrated by the contra-

dictions that prevailed on grocery-store shelves.

It was not until President Bush took ofﬁce in the late

1980s that legislative and regulatory efforts again focused

on nutrition labeling. Senators Metzenbaum, Kennedy,

and Hatch and Representatives Waxman and Madigan

renewed the spirit of the 1970s with nutrition labeling

regulations that ultimately resulted in mandatory label-

ing, nutrient content and health claim deﬁnitions, and

federal preemption, now known as NLEA. While these

legislators were lobbying for mandatory nutrition labeling

laws, the National Academy of Sciences’ Institute of

Medicine (IOM) issued a report entitled Nutrition Label-

ing: Issues and Directions for the 1990s (11). The IOM

report recommended changes in food labeling to assist

consumers in implementing the recommendations of the

Surgeon General (7) and the National Research Council

(8). The FDA responded by working with all concerned

parties, including industry, consumer groups, and the

states, to deﬁne regulations that would meet the goals

set out by the IOM report.

On November 8, 1990, President George Bush signed

into law the Nutrition Labeling and Education Act

(NLEA) of 1990 (12), which dramatically changed the

way that food products were labeled in the United States.

The

NLEA represents a

comprehensive mandatory nutri-

tion-labeling system, designed to help consumers meet the

U.S. Dietary Guidelines (6) and reduce their risk of chronic

diseases. The intent of these regulations was to the

provide guidance to food manufacturers and package

designers needed to ensure consistent presentation of

nutrition information and to prevent erroneous nutrient

content and health claims.

The only signiﬁcant change that has been made to the

Nutrition Facts panel since the implementation of NLEA

in the early 1990s was on July 9, 2003, when FDA issued a

NUTRITION LABELING 825

regulation requiring manufacturers to also list trans fat

on the Nutrition Facts panel of food products. This regula-

tion was the result of growing scientiﬁc reports conﬁrming

the relationship between trans fat and an increased risk of

coronary heart disease.

REGULATORY AGENCIES

Regulation of food labeling falls primarily under the jur-

isdiction of two federal agencies: the Food and Drug Admin-

istration (FDA) and the United States Department of

Agriculture (USDA) (13). The USDA’s Food Safety and

Inspection Service (FSIS) oversees food labeling of products

containing meat or poultry (Z2% or more cooked, Z3%

raw). All other food products fall under the jurisdiction of

the Center for Food Safety and Applied Nutrition (CFSAN)

of FDA. FDA regulations are governed by the F ederal F ood,

Drug, and Cosmetic Act (FDCA) and the F air Packaging and

Labeling Act (FPLA). [The Nutrition Labeling and Educa-

tion Act of 1990 (NLEA) is an amendment to the FDCA.]

The USDA’s regulatory role and responsibilities are deﬁned

by the Federal Meat Inspection and P oultry Products

Inspection Acts . Because the two agencies are governed by

separate laws, they have different missions, philosophies,

and approaches to food labeling. This results in subtle

differences throughout the regulations.

The USDA’s primary regulatory role has been to pre-

vent public health hazards resulting from improper hand-

ling of meat and poultry during production and packaging.

The USDA’s network of ﬁeld ofﬁces are responsible for

conducting frequent plant inspections, and the national

ofﬁce administers a label preapproval program. Through

these mechanisms, the USDA tightly controls food label-

ing during the production process. Unlike the USDA, the

FDA has not been funded to function as an inspection

service; therefore, the agency does not have the staff

resources to play a hands-on role in label development

and approval. The FDA relies on postmarket surveys to

enforce the regulations.

As discussed above, Congress passed the NLEA in 1990,

mandating the FDA to initiate extensive changes in the

content and format of the nutrition label. FDA responded

by issuing ﬁnal rules in January 1993 (14). Nutrition

labeling of USDA products was not included in the Con-

gressional mandate; however, the USDA decided to follow

suit in order to prevent consumer confusion arising from

two different nutrition labels (15). In most of the signiﬁ-

cant aspects of nutrition labeling, the USDA regulations

mimic the FDA’s; however, the regulations diverge in a few

areas. For example, the USDA has different exemption

criteria, more relaxed rules for use of the ‘‘Simpliﬁed’’

format, and less extensive requirements for statements

that accompany nutrient content claims.

NUTRITION FACTS PANEL

The Nutrition Facts panel presents the nutrient proﬁle of

a food product on a per serving basis. Since a goal of NLEA

was to make nutrition information easy for consumers to

locate, read, and understand, both the content and layout

of the Nutrition Facts panel were studied extensively

before the regulations were ﬁnalized. The Nutrition Facts

panel focuses on the nutrients important to the health

of Americans (e.g., calories, fat, saturated fat, trans fat,

cholesterol, sodium, ﬁber). The nutrient content of the

food is presented in absolute terms (e.g., grams, milli-

grams) and as a percentage of the Daily Value (% Daily

Value) for those nutrients where FDA has establised a

Daily Value. Percentages provide a method for comparing

the nutrient proﬁle of the food to recommended nutrient

intakes. Larger food packages are also required to include

a list of the Daily Values at two calorie levels (i.e., 2000

and 2500) in a footnote at the bottom of the Nutrition

Facts Panel. The serving size information has been stan-

dardized to make it easier to compare similar products.

Serving sizes are presented in common household mea-

sures (e.g., cups, tablespoons) to help consumers visualize

portion sizes, as well as metric units (e.g., grams), to

encourage familiarity with the International System of

Measures (13).

To maintain a consistent look from package to package,

both FDA and USDA regulations explicitly deﬁne

the layout of the Nutrition Facts panel (Figure 1). A

hairline box surrounds the nutrition information, which

is presented in a required order. The type size and leading

(spacing between lines of type) of each line is speciﬁed.

Boldface type is used to enhance certain nutrients,

and other nutrients are indented. Heavy-, medium-,

and lightweight rules are incorporated in speciﬁed

places.

To provide some ﬂexibility in tailoring the Nutrition

Facts panel to various food packages, the regulations allow

for several variations of the Nutrition Facts layout pic-

tured in Figure 1. These variations are not a random

choice; they each have explicit usage criteria (13). Format

options are based on the nutrient proﬁle of the food.

Display options are available to accommodate different

package shapes and sizes, as well as special situations

(e.g., variety packages, foods for children, bilingual labels).

In addition, the regulations allow for modiﬁcation of the

Nutrition Facts on packages that have limited space for

labeling.

Format Options

The format of the Nutrition Facts panel refers to the

nutrients listed on the panel (13). The regulations deﬁne

14 mandatory nutrients for inclusion in the Nutrition Facts

nel; th

e ‘‘Full’’ format includes these 14 nutrients (Figure

1). In addition, the regulations allow for inclusion of certain

nonmandatory nutrients, on either a required or voluntary

basis. The Extended format accommodates the inclusion of

nonmandatory nutrients in a speciﬁed order. An example of

the Extended format is presented in Figure 2.

When a food product has one or more mandatory

nutrients at an insigniﬁcant level (e.g., nutrient decla-

ration of 0), an abbreviated format may be used.

The ‘‘Shortened’’ format is available for FDA products

that have between one and six insigniﬁcant nutrients.

With this format, insigniﬁcant nutrients may be listed in

a footnote stating, ‘‘Not a signiﬁcant source of [list of

826 NUTRITION LABELING

insigniﬁcant nutrients].’’ FDA products with seven or

more insigniﬁcant nutrients may bear the Simpliﬁed

format that allows insigniﬁcant nutrients and the Daily

Values table in the footnote to be omitted. However, if

nonmandatory nutrients are declared, then a variation,

called the ‘‘Simpliﬁed Extended’’ format, is used. USDA

employs a different approach to the Simpliﬁed format. The

Simpliﬁed format is available for products that have one

or more noncore, mandatory nutrients at insigniﬁcant

levels. With all these abbreviated formats, ﬁve core

nutrients (viz., calories, total fat, sodium, total carbohy-

drate, protein) must be listed, even if they are insignif-

icant. Figure 3 presents examples of the abbreviated

formats.

Display Options

The ‘‘Standard’’ display (vertical column) pictured in

Figure 1 is the ‘‘model’’ Nutrition Facts layout from which

all others are derived (13). On packages with limited

vertical space, the ‘‘Modiﬁed’’ (footnote to the side) display

may be used. If neither the Standard nor Modiﬁed dis-

plays will ﬁt, then the ‘‘Tabular’’ (horizontal) display may

be used. Figure 4 presents the Modiﬁed and Tabular

displays.

To accommodate special packaging and labeling situa-

tions, other displays are allowed. The ‘‘Dual Column’’

display provides for listing nutrients on an ‘‘as prepared’’

as well as an ‘‘as packaged’’ basis. The ‘‘Aggregate’’ display

Figure 2. Extended Nutrition Facts format.

Figure 1. Design features of the Nutrition Facts panel.

NUTRITION LABELING 827