EAGLE RIDGE 1

March 19, 2002

Mr. Neil Blickman

Federal Trade Commission

600 W. Pennsylvania Ave., N.W.

Washington, D.C. 20580

Petition to Establish a New Generic Subclass

The Dow Chemical Company (Dow), world headquartered in Midland, Michigan, hereby 

submits this Petition to the Federal Trade Commission (FTC) for the establishment of a new

generic subclass (lastol) within the existing olefin category. 

Dow seeks to establish a generic subclass for its new crosslinked elastic fiber (CEF) for three

reasons: 

1. Dow CEF fiber has the same general chemical composition as the FTC’s established olefin 

 generic fiber category:

- the fiber-forming substance in CEF is composed of at least 85 percent by weight of

ethylene, propylene, or other olefin units.

- specifically, greater than 98 percent by weight of the fiber-forming substance in CEF

is composed of ethylene and other olefin units (e.g., 1-octene).

2. Dow CEF, while having the general chemical composition of olefin, has a unique chemistry,

molecular design, and fiber structure which enables distinct, important properties to the

consumer:

- the fiber is elastic with a wide temperature tolerance, enabling comfort stretch

garments that can be repeatedly washed, dried, and ironed without loss of stretch and

elasticity

3. Dow CEF fiber’s distinctive elasticity and temperature tolerance features enable olefin to be

considered for new apparel applications beyond the conventional socks and thermal underwear:

- stretch cotton separates like dresses, shirts, and slacks, are now possible and desirable

for their comfort stretch and easy-care properties

1
In short, Dow CEF is an atypical olefin fiber differing significantly – in chemistry, process, and

properties – from conventional olefin fiber manufactured for apparel uses today per the FTC’s

definition. Dow CEF is not a rubber, per the FTC’s definition, because the fiber-forming

substance in Dow CEF is a polyolefin with low but significant crystallinity versus an amorphous

(non-crystalline) polyolefin. And last, Dow CEF is not a spandex, per the FTC’s definition,

because CEF is not made of polyurethane. 

The FTC definitions for olefin fiber1, rubber fiber2, and spandex fiber3 are listed below for

reference.

1Olefin. A manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed

of at least 85 percent by weight of ethylene, propylene, or other olefin units, except amorphous (noncrystalline)

polyolefins qualifying under paragraph (j)(1) of this section.

2Rubber. A manufactured fiber in which the fiber-forming substance is comprised of natural or synthetic rubber,

including the following categories: 

(1) A manufactured fiber in which the fiber-forming substance is a hydrocarbon such as natural rubber,

polyisoprene, polybutadiene, copolymers of dienes and hydrocarbons, or amorphous (noncrystalline)

polyolefins.

(2) A manufactured fiber in which the fiber-forming substance is a copolymer of acrylonitrile and a diene

(such as butadiene) composed of not more than 50 percent but at least 10 percent by weight of acrylonitrile

units. 

The term lastrile may be used as a generic description for fibers falling within this category. 

(3) A manufactured fiber in which the fiber-forming substance is a polychloroprene or a copolymer of

chloroprene in which at least 35 percent by weight of the fiber-forming substance is composed of

chloroprene units.

(emphasis added)

3Spandex. A manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer

comprised of at least 85 percent of a segmented polyurethane.

2
I Dow Crosslinked Elastic Fiber (CEF): The Atypical Olefin Fiber

A. Properties of Dow CEF Versus Conventional Olefin

1. Unique Chemistry of Dow CEF

Dow CEF is the first manufactured olefin fiber founded on metallocene-based

polyolefin elastomer chemistry. Although the fiber-forming substance in Dow CEF

is made from olefin monomers, Dow CEF fiber has a unique molecular structure, a

unique morphology and unique properties when compared with any olefin fiber

previously seen on the market. This unique combination of properties is a direct

result of the polymerization chemistry, which includes the use of a constrained

geometry catalyst, which is a member of the metallocene family. 

This catalyst has a single type of active site allowing precise control of molecular

architecture of the polymer. Specifically, greater than 98 percent of the fiber forming

substance in Dow CEF is a homogeneously branched ethylene4 interpolymer5

composed of ethylene and other olefin comonomer units (typically octene). 

Very technically, the polymer in Dow CEF contains short chain branching; has no

measurable high-density polymer fraction; has a narrow, essentially single peak in

TREF (temperature rising elution fractionation) and differential scanning calorimetry

(DSC) profile curve; and has a narrow molecular weight distribution prior to

crosslinking. In simple terms, the molecules in Dow CEF are all very similar in size

and composition to each other. These molecular characteristics lead to important and

distinct fiber properties.

The alpha-olefin comonomer in Dow CEF is typically octene, and is present at a high

level (typically in excess of 30 weight percent). This high comonomer content leads to

Dow CEF fiber’s low but significant level of crystallinity and low density. 

In contrast, olefin fiber manufactured today is based on conventional multi-site

catalyst technology (such as Ziegler/Natta catalysts). Consequently, it has a broad

compositional molecular weight distribution and low or no comonomer content. 

4Homogeneously branched ethylene polymer. Refers to an ethylene interpolymer in which the comonomer is

randomly distributed within a given polymer molecule and where substantially all of the polymer molecules have

the same ethylene to comonomer molar ratios (WO 99/60060) and are manufactured using so called

homogeneous or single site catalyst systems known in the art as metallocene catalyst or constrained geometry

catalysts system. (See also US 6,140,442, “Elastic Fibers, Fabrics and Articles Fabricated therefrom” and US

6,194,532, “Elastic Fibers”)

5Interpolymer. Refers to polymers prepared by the polymerization of at least two different types of monomers,

typically ethylene and octene.

3
2. Unique Morphology of Dow CEF 

As a result of its unique chemical structure, Dow CEF has lower crystallinity

than conventional olefin fibers. (See Summary Table 1, page 15.) Specifically, the

high comonomer content leads to Dow CEF fiber’s low but significant level of

crystallinity (12 – 16 weight percent) (Figure 1a, page 5) and low density (from 0.87

to 0.875 g/cc). Unlike conventional olefin fiber where the polymer crystals are in

lamellae form, the crystals in the Dow CEF fiber-forming substance are in fringe

micelle form. The fringed micellar crystalline morphology6

 and the low but significant

level of crystallinity in Dow CEF imparts elastic properties not seen in other olefin

fiber manufactured today. This unique morphology of the Dow CEF polymer results

in high stretch (such that the fiber can be stretched to at least five times its original

length before breaking) and high elasticity or snap back (such that when a fiber is

stretched to twice its length and then released, the fiber recovers to within 25% of its

original length). 

In contrast, conventional olefin fiber, such as drawn polypropylene fiber (Figure 1b,

page 5), is highly crystalline with degree of crystallinity greater than 50 percent and

density greater than 0.90 g/cc. Additionally, conventional olefin has very low stretch

(for example, 33 percent elongation to break) and no significant elasticity at high

stretch. 

This combination of elasticity, elongation, and mechanical strength found in Dow 

CEF fiber are not found in conventional olefin fiber manufactured today. (WO

99/60060, US Patent allowed, but not yet issued.)

6 Benedikt, George M., Brian L. Goodall (1998). Metallocene-Catalyzed Polymers: Materials, 

Properties, Processing & Markets. Norwich, New York: Plastics Design Library, pp. 127-133.

4
Figure 1: Differential scanning calorimetry (DSC) showing crystallinity and melting

peak temperature of Dow CEF fiber (a) versus conventional drawn polypropylene

fiber (b). Degree of crystallinity is determined from heat of fusion in the melting

endotherm.

Dow CEF (a)

Drawn Polypropylene Fiber (b)
56

3. Unique Manufacturing Process of Dow CEF

Dow CEF fibers are manufactured by melt spinning followed by crosslinking.

Melt spinning

The Dow CEF fiber is fabricated using a melt spinning process. For instance, the

polymer may be melt spun into mono-filament or multi-filament fibers with a broad

range of deniers (ranging from less than 20 to over 140 denier) on conventional 

elastic melt spinning equipment, such as that used for thermoplastic urethane fibers. 

In one specific example, the fibers were separately melt spun on fiber extrusion

equipment consisting of an extruder, gear pump and spinneret. The extruder provided 

a melt temperature of 236°C and each polymer melt stream was fed to the gear pump

which pressurized the melt and passed it through a 200 mesh pack followed by a 34

hole spinneret die. The spinneret had a 4:1 L/D and the holes had a diameter of 800

microns. The resin output from the spinneret was controlled at 0.78 gram/hole/ 

minute. The fibers were quenched with a room temperature air high velocity blower.

Crosslinking

After spinning, the polymer chains in CEF fiber are not connected to one another

through covalent bonds. As a result, in an appropriate solvent, such as boiling xylene

or tri-chloro benzene, the polymer will dissolve. The fiber will also begin to flow and

deform if heated above the crystalline melting point (about 68°C). In order to prevent

dissolution and impart high-temperature dimensional stability, the fiber is crosslinked. 

After the crosslinking process, the polymer chains in the fiber are linked to one 

another via covalent bonds (Figure 2, below). The crosslinked fiber is characterized as

having xylene extractables of less than about 70 weight percent as defined in

accordance with ASTM D-2765.

Figure 2: Schematic of morphology of crosslinked Dow CEF fiber (a) versus

uncrosslinked polymer (b).

Dow CEF Fiber (a) Uncrosslinked Fiber (b)

Crosslinks and Crystals Fringe-Miceller Crystals
7

The crosslinking process is conducted by any means capable of economically forming

covalent links between the polymer chains including electron beam, beta irradiation,

gamma irradiation, corona radiation, peroxides, allyl compounds, silane compounds

and UV radiation with or without crosslinking catalysts. For example, crosslinking

can be accomplished via high energy electron beam irradiation of the fiber spools. 

The irradiation source can be any electron beam generator operating in a range of 150

kilovolts to 12 megavolts with a power output capable of supplying the desired

dosage in megarads. The voltage can be adjusted to appropriate levels. The

irradiation is usually carried out at a dosage between 3 to 35 megarads. Irradiation

may be carried out at room temperature or at a lower temperature, and is typically

conducted on the fiber spools after fiber spinning.

4. Unique Properties of Dow CEF

Dow CEF fibers have elasticity, high temperature stability, and chemical

resistance

Elasticity

The low but significant level of crystallinity imparts elasticity to the Dow CEF fiber

whereas no olefin fiber manufactured today is elastic. Elasticity is defined as the 

ability of a strained material to recover its original size and shape, immediately after

removal of the stress that causes deformation7. DOW CEF fiber’s favorable stretch 

(at least five times its original length before breaking) and elasticity or snap back

(stretching to twice its length then, when released, recovering to within 25 percent of 

its original length) are a consequence of its low but significant level of crystallinity

(Figure 3, page 8). Because of this, CEF can be successfully used in clothing 

applications where stretch is desired. 

In contrast, conventional olefin fiber is highly crystalline, with degrees of crystallinity

of greater than 50 percent. The crystals of conventional olefin fiber are also in

lamellae form, unlike crystals in the Dow CEF fiber-forming substance which are in a

fringe micelle form. As a result, conventional olefin fiber is stiff, and essentially,

non-elastic. Typical olefin fibers (in their manufactured, “drawn,” form) exhibit very

low elongation before breaking (typically less than 50%) and therefore cannot be

successfully used in today’s apparel markets for stretch clothing.

7 KoSa Communications and Public Affairs (1999). Dictionary of Fiber & Textile Technology.

Charlotte, N.C.: KoSa, p. 69.
8

Figure 3: Tensile data of Dow CEF fiber (a) versus drawn polypropylene fiber (b).

Figure 4: Dynamic mechanical thermal analysis (DMTA) of Dow CEF (a) versus

drawn polypropylene fiber (b). Note: Dow CEF maintains its mechanical integrity

well above its crystalline melting point (ca. > 68°C), whereas drawn polypropylene

does not.
9

High temperature stability, chemical resistance

Dow CEF is substantially crosslinked with covalent crosslinks that connect adjacent

polymer chains into a contiguous 3-dimensional polymer network (Figure 2a, page 6). 

This crosslinked polymer network structure allows Dow CEF to maintain its shape

and mechanical integrity above its crystalline melting temperature. Above its melting

temperature, the mechanical integrity of Dow CEF is provided by covalent crosslinks.

In fact, Dow CEF retains its shape at temperatures up to 220°C – well in excessof

conventional olefin’smelting pointwhich occurs at or below170°C(Figure4, page 8; Figure7, page

10).Furthermore,Figure5, below,showsthe heatstabilityofDowCEFin nitrogen up to about 350°C

(>220°C). 

This crosslinked polymernetwork structure alsoallowsDowCEFtomaintainitsintegrityin solvents

which typicallydissolve the starting polymer(Figure7, page10).In contrast, conventional olefinfiberis

not crosslinked and therefore losesshape andmechanicalintegrityand/or dissolves above its crystalline

melting temperatureswhich range up to about 170°C.

Figure 5: DSCmelting curve in nitrogen ofDowCEFfromroomtemperature

to 500°C.

Furthermore,Figure5, above,showsthe heatstabilityofDowCEFin nitrogen up to about 350°C.
10

25oC, CEF 25oC, Drawn PP

220oC, CEF 170oC, Drawn PP

Uncrosslinked fiber

after heating in TCB

150°C/2 hours

Crosslinked fiber

after heating in

TCB 150°C/2 hours

Figure 6: PhotographsshowingmechanicalintegrityofDowCEF(a)

versus conventional olefinfiber(b)which losesshape and integrityat 170°C.

Dow CEF ConventionalOlefinFiber

a1 b1

a2 b2

Figure 7: Photographsshowing uncrosslinked fiber(a)which has dissolved inTCBafter heating to

150°Cand crosslinkedDowCEFfiber(b)which continuestomaintainitsshape and structural

integrityundersame conditions.Note: youcan see theDowCEFfiberstill presentin theTCB

solvent.

 (7a) (7b)
11

DowCEFfiber’s abilitytowithstand high temperatureshas compelling advantagesforthe textile

manufacturer: theycan usemore efficient dye and processmethodsrequiringtemperaturesin excessof

170°C. There are alsoadvantagesfor consumers:theycan repeatedlywash, dry; and iron fabrics

containingCEFattypicaltemperatures(up to 210°C)without destroyingthe stretch properties ofCEF

fiber. In contrast,since conventional olefinfibermanufacturedtodaylosesitsshape andmechanical

integrityin temperaturesrangingfrom105 – 170°C,it cannotwithstand the rigors of high heat and

repeatedlaunderings. Consequently, conventional olefinfiberis notwidelyused in apparel applications

todaywhere the consumerseeks easywash‘n’wear care. 

Therefore,DowCEFfiberis a uniquelydifferentiatedolefinfiber and exhibitssignificant property

improvementsincluding shape retention and stabilityat veryhigh temperaturesplusimproved fabric

processingand consumer care characteristicsnotfound in conventional olefinfibermanufactured

today.

B. Propertiesof Dow CEFVersusRubberFibers

1. DifferencesinChemistryandMorphology

Dow CEFfiber differssignificantly fromrubber fibers. The fiber-formingsubstance inDowCEF

is a polyolefinhaving a lowbutsignificantlevel of crystallinity. Therefore,DowCEFdoes notfall

withintheFTCdefinition of a rubber(FTCdefinition ofrubber, page 2).

Evidenceoflowbutsignificant crystallinityinDowCEFfiberis provided bya standard differential

scanningcalorimetry(DSC)technique (Figure8, page 12). 

CEFfiber exhibits approximately16% crystallinityand amelting point of approximately68°C. In

marked contrast,the rubberfiber exhibitsno crystallinityasindicated bylack of a discernibleDSC

endotherm.
12

Figure8: DifferentialscanningcalorimetryofDowCEF(a) versusrubber(b). Degreeof

crystallinityis determined fromheat offusion inmelting endotherm.

Dow CEF (a)

Rubber Fiber (b)
13

2. Process Distinctions

Dow CEFfiber isproduced by a meltspinning / crosslinkingprocess. In contrast,rubberfibers are

commonlymade byextruding a pre-curedaqueouslatex dispersion into an acidbath. This extrudateis

coagulatedto solidifythe rubber. The resulting thread then proceedsinto a dryingand a curingoven.

Alternatively,rubberfibers can bemade byslitting prevulcanized sheets(cutrubber). 

Therefore,CEFand rubberfibers aremanufacturedfromradicallydifferentmaterials via different

processes.

3. PropertyDifferentiation

Rubber fibers arenot crystalline,whereasCEFfibers have a low butsignificantlevel of

crystallinity. As a result,CEFfibers have unique differentiatingproperties.

Rubberfibers are amorphous(non-crystalline) polymers, and are vulcanized typicallyusing sulfur and

heat. As a resultofthis chemicalstructure,rubberfibers have uniformtensileproperties acrossa broad

temperature range. In contrast,CEFfibers havemechanical propertieswhich derive fromboth the

crystallinityand covalent crosslinks between carbon atoms–without using sulfur. At low

temperature,the presenceof crystallitesdominatesthemechanical properties ofCEF. Asthe

temperature israised above the crystallinemelting point(ca.>68°C),themodulus ofCEFfibers drops

byan order ofmagnitude;themodulus abovemelting point is determined solelybythe degreeof

covalent crosslinks. Therefore,CEFhas unique temperature-dependentmechanical propertieswhich

are radicallydifferentfromthoseofrubberfibers. Since rubber has absolutelyno crystallinity, the

modulusis

essentiallyflatwith respectto temperature increases. The figure shown below(Figure9) dramatically

demonstratesthisfeature.

Figure9: Dynamicmechanicalthermal analysis(DMTA) of DowCEF(a) versusrubberfiber(b).
14

Secondly, since CEF has a low but significant level of crystallinity at room temperature, the fiber

exhibits higher tenacity (strength) at break compared to rubber fiber which is amorphous (Figure 10,

below). The improved mechanical strength and toughness of Dow CEF is important to survive

rigorous textile fabrication processes.

Figure10: TensiledataofDowCEFfiber(a) versusrubberfiber(b)showing lowertenacityat break

ofrubberfiber due to rubber’s amorphous character.

And last,sinceDowCEFhas a lowbutsignificantlevel of crystallinityatroomtemperature,CEF

exhibitshighertensileset(lower elasticrecovery)than rubberwhen extended to greaterthan 100%

elongation. The 5-cycle tensilesetmeasurement(Figure11, page 15)showsthis contrasting behavior

betweenCEFand rubberfiber. The permanentset ofCEFis a directmanifestation ofits crystallinity

and standsinmarked contrast to the lowtensileset ofrubberfibers.
15

Figure 11: Tensileset dataofDowCEF(a) versusrubber(b)showing permanentset ofDowCEF

versus negligible set ofrubberfiber(5 cycle elongation).

SummaryTable#1

Property CEF Conventional

Olefin8

Rubber

Crystallinity,wt% 12 to 16 >50 0

Elongation,% >400 <15-200 600 – 800

BreakingStrength

(gm/den)

>0.9 1.7 – 6.8 0.45

InitialModulus 0.3 34 – 56 0.02

Density (gm/cc) 0.87 – 0.875 0.90 – 0.91 ~ 1.0

Dissolution

Characteristics

Does not dissolve Dissolve Does not dissolve

Temperature

Stability

Up to>220°C Up to 170°C Up to 350°C

Manufacturing

Method

Meltspinning

followed by

crosslinking

Meltspinning Extrusion/vulcanization or

splitting prevulcanized

sheets

8

Polypropylene drawn fiber data (elongation, breaking strength,initialmodulus) from Fourne, Franz (1998). Synthetic Fibers:

Machines and Equipment, Manufacture, Properties. Cincinnati, Ohio: Hanser/Gardner Publications, Inc. pp. 840 & 850.
16

II Dow CEF: A New Generic Subclass — Lastol

A. WhyDow SeeksaNewGenericSubclass

DowCEFmeetsthe broad definition of olefinfiber. However,CEFhas unique elasticproperties,

thermalresistance,molecularstructure,morphology, and propertyimprovementswhich differentiate it

fromconventional olefinfibermanufacturedtoday. Today’solefin– largelyseen in carpet, thermal

underwear, and socks – does not offerthe consumerstretch orthe easy-care characteristicsgained

through high temperature tolerance. To textilemill producers,CEFenables processeconomies and the

production of newproductswith atypicalstretch and performanceproperties. To the consumer,CEF

offers awider choice in garments containing stretch fabricplusthe benefitof easy-care launderingat

highertemperatureswithout degradationofthe stretch fiber.

B. ProposedNewGenericSubclassName –Lastol 

Dowrecognizesthat a newsubclassname shouldcapture the chemicalstructurewhile also

referencingthe radical distinction. Dowhas determinedLastol to be the descriptive newsubclass

becauseit connotes an elasticized olefin. Dowproposed the following definition forLastol:

Amanufactured crosslinked elasticfiberinwhich a)the fiber-forming substance is a synthetic

polymer,with lowbutsignificant crystallinity, composed of at least99 percent byweight of ethylene

and at leastone other olefinunit,and b)whereinthe fiber exhibitssubstantial elasticity and heat

resistance properties not presentin traditional olefinfibers.

III CommercializationPlanandTimeTable

Commercialization ofDowCEFisimminent – occurringearlyin the second quarter of 2002. 

Beginningin 1999,Dowidentified and beganworkingwith developmental partnerswho are leadersin

the fibermanufacturingand apparelindustryaround theworld. Since the second quarter of 2001,CEF

has been successfullymade on commercial-scale spinning equipment,with resulting quantities

subsequentlyproduced and used in awide range offabricsincluding both knits andwovens. These

fabrics have been used tomake a varietyof goods,butmost notablyforthose in the apparelmarket and

its various end-usesegments.

GarmentsmadewithCEFhave been tested and found tomeet or exceed allstandard industry

specifications. Themarkettesting processof garmentswith leading retailersis presentlyunderway,

with completion expectedwithinthe comingweeks.
17

If youhave questionsregardingthisPetition, pleasecontactMargaretRogersinDow’sWashington

D.C. office (202 429-3403)StephenKrupp, our businessattorney(979 238-2889). Steve islocated in

Freeport,Texas.

Thank youfor yourtime and consideration.

Sincerely,

AntonioTorres

GlobalBusinessDirector

DowFiberSolutions

Cc: StephenKrupp

MargaretRogers