recycled nylon 6

8152019 Recycled Nylon 6

httpslidepdfcomreaderfullrecycled-nylon-6 114

Recycled Nylon 6

Material Snapshot

Material Scenario

Undyed recycled nylon 6 woven textile General process for chemical depolymerization of waste nylon

6 materials primarily carpet for secondary caprolactam and nylon 6 fiber production Major unitprocesses include collection of post-consumer waste sorting shredding depolymerization distillingmelt-extrusion yarn spinning and textile construction Data used in this report come from varioussources and the scenario is not geographically specific

Common Uses In Apparel And Footwear

Due to the fact that recycled nylon 6 is produced from virgin quality caprolactam it can share manyof the same uses as virgin nylon The manufacturers of EcoNyl have used recycled nylon from fishingnets in apparel including socks swimwear and underwear (Ditty 2013)

Alternative Textiles That May Be Substituted For Materialbull Virgin nylon 6 bull Virgin nylon 66 bull Mechanically recycled nylon 6 bull (Refer to virgin nylon 6snapshot for other substitutes)

Life Cycle Description

Functional Unit

1 kilogram of chemically recycled undyed nylon 6 fabric

System Boundary

Cradle to undyed woven fabric The data presented within include all steps required to turn the post-consumer material into woven fabric including transportation and energy inputs Capital equipmentspace conditioning support personnel requirements and miscellaneous materials comprising lt1 byweight of net process inputs are excluded Incineration of waste materials is not included in this study

Allocation

Cut-off approach The ldquofirst liferdquo of the product (eg as carpet) is considered entirely separate from theldquosecond liferdquo (eg as a shirt) thus any environmental impacts of producing the waste material used toproduce the recycled nylon are allocated entirely to the waste material

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2

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Unit Process Descriptions

Raw Material Sourcing

A wide range of nylon waste is generated that can be collected processed and recycled into newnylon materials A significant barrier to efficient collection and recycling is the diversity of nylonmaterials ndash eg nylon 6 nylon 66 nylon 610 nylon 11 nylon 12 etc Nylon collection and recycling

is most cost efficient when there are large volumes of relatively homogenous waste material (egcarpet) Consequently collection and recycling is mostly nylon 6 and nylon 66 waste carpet withadditional waste from virgin nylon production (Gupta and Kothari 1997 p 616) fishing nets (Coplare2012) and textiles (pre- and post-consumer) None of these materials are collected via multi-materialresidential curbside collection programs Rather these materials are typically obtained throughrelationships with waste generators or takeback programs such as Interfacersquos ReEntry program(Interface nd ldquoCarpet to Carpet Recyclingrdquo)

Processing

Alternative methods for recycling waste nylon materials and products include mechanical extraction(also called melt processing) and various methods of depolymerization followed by repolymerization

(Wang 2006 pp 2-5) Processors typically choose a method that results in a specified level of outputquality for a given waste nylon source Relatively clean nylon can be depolymerized to provide inputsto polymerization of virgin quality nylon conversely nylon with some contamination can be meltprocessed into lower quality nylon (Mihut et al 2001 p 1458)

Mechanical processing1 involves cleaning the collected raw recyclate shredding it into small piecesdensifying the shredded material to increase uniformity melting the material and extruding the meltedmaterial to either form pellets or filaments Pellets are packaged and shipped to customers that usemechanical means such as injection molding or extrusion to form a wide variety of nylon products

Filaments are formed (whether directly from shredded nylon or from pellets) by extruding the meltthrough a spinnerette and drawing twisting and winding the resulting fibers that can then beprocessed further into yarn (EOS nd ldquoRecycling Nylon CarpetndashMelt Processingrdquo) Carpets that are

shredded and melted without segregating the nylon from the backing material generally requirea variety of additives to enhance compatibility of the mixed polymers Even when segregatedmechanically recycled nylon generally results in a reduction in functional and performance properties(Lozano-Gonzaacutelez et al 2000) Nylon 66 is often mechanically recycled whereas nylon 6 iscommonly chemically recycled and can easily be processed back into the same products from whichthe original recovered nylon originated (Zeftron nd ldquoReclamation amp Recyclingrdquo)

Due to its relatively high value compared with other polymers and because it easily oxidizes instorage resulting in gels when melt processed (Datye 1991 p 47) nylon 6 is a good candidate forchemical recycling via depolymerization (Wang 2006 p 2 EOS nd ldquoNylon Carpet RecyclingndashDepolymerizationrdquo) Similar to mechanical recycling carpets go through a process of sorting todetermine polymer type shredding and separation using density techniques of the face fiber (the

nylon 6) from the backing (synthetic polymers andor bio-based materials) (Lu 2010 pp 38-39) Theseparated nylon 6 is then batch processed in a depolymerization reactor

The reactor is maintained as a nitrogen-free environment while the nylon 6 is treated with super-heated steam (Wang 2010 p 139) at elevated pressure (410-450 kPa) and temperature (250-340oC)(Braun et al 1999 pp 471 476 Dmitrieva 1986 p 231) to produce an aqueous solution of 10-50caprolactam (Gupta and Kothari 1997 pp 617-618) Catalysts such as an alkali (sodium hydroxide)metallic sodium metal oxides or phosphoric acid and its salts are used to increase caprolactamyields although they result in differing levels of purity (Gupta and Kothari 1997 pp 617-618 Dmitrieva1986 p 230)

The aqueous solution of caprolactam can be contaminated with additives used in the original productsuch as dyes lubricant preparations and various fillers (Dmitrieva 1986 p 234) To remove impurities

the recovered caprolactam may be distilled in the presence of an aqueous alkali at a temperature of100-150oC (Dmitrieva 1986 p 238)

1 Mechanical processing generally includes a melting process and the terms are used interchangeably



3

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Alternatively impurities may be removed via other methods such as solvent extraction membraneseparation adsorbants or oxidizing agents (Gupta and Kothari pp 49-50) The resulting purecaprolactam is repolymerized into nylon 6 in the same fashion as virgin nylon 6 (see the Nylon 6Material Snapshot)

Whether following directly from polymerization or from melting of pellets the resulting nylon 6 isextruded through a spinneret typically comprised of 01-04mm diameter holes (Mather amp Wardman2011) The emerging filaments are then extended in jets once they emerge from the spinneretsolidified with water in a quench zone heated in a steam conditioning process and treated with aspin finish before they are wound up (Bunsell 2009 pp 201-202) The fibers are drawn to extendtheir length orient the polymer molecules and improve crystallization to obtain desired propertiesWhile the fibers may be drawn to between 200-500 of the original length the higher draw ratiosare for technical industrial applications and the lower ratios (200-250) are for apparel (Bunsell2009 p 203) After drawing filaments are subject to twisting texturing and heat setting to createthe final yarn There are many levels of heat setting to increase the thermodynamic definition to themorphology throughout the yarn manufacturing process (Bunsell 2009 p 204) Finally the yarn isthen wound on spinning machines and finally re-wound on bobbins to create the final product (Akovali2012 pp 133-134)

While nylon 66 can be depolymerized it is not commercially viable due to the nylon 66 polymerbeing derived from two intermediate raw materials adipic acid and hexamethylene diamine (HMDA)(see the Nylon 66 Material Snapshot) Lab depolymerization of nylon 66 by several routes has beendemonstrated (Patil and Madhamshettiwar 2014 Duch and Allgeier 2007) but has not been scaled toindustrial operations

Textile Final Processes

Recycled nylon yarn which has been previously wound and spun can be woven into a variety oftextiles

Process Inputs

Energy

Energy is necessary for collection of post-consumer waste (including transport sortingshredding grinding cleaning) processing (depolymerization distilling melt-extrusionyarn spinning) and textile construction Cradle to gate production of 1 kg of recyclednylon yarn requires 172 MJ2 (EcoNyl 2011 p 13) Depolymerization and repolymerizationprocesses filament production and yarn spinning rather than waste collection andtransportation are the major energy using processes (EcoNyl 2011 p 13) Weaving wasidentified by van der Velden et al (2014 p 355) as having the highest impact for polymerfibers when yarns are thin (lt70 decitex) they calculated that weaving undyed greige textile(70 decitex) requires 229 MJ (van der Velden 2014 pp 351-352)3 Total cradle to gaterecycled nylon energy is 401 MJkg

Water

Process water is used throughout the cradle to gate recycled nylon life cycle particularlyin cleaning the collected waste steam treatment and post depolymerization purificationof caprolactam Cradle to yarn water use is 84 Lkg Of this total collection is 185 Lkgrecycled nylon yarn and processing is 655 Lkg recycled nylon yarn (EcoNyl 2011 p 13)

Direct use of water weaving is minimal (unless water jet weaving is used) Howeverwater use is embedded in electricity production (approximately 0022 LMJ) leading to anestimated 5 L of water per kg of woven textile for the 229 MJkg associated with weavinggreige textile (Appendix Table B)

2 All reported EcoNyl inputs and outputs data are an average of two EcoNyl products FDY Raw White and TexturedYarn Raw White (EcoNyl 2011)3 As nylon 6 recycling via depolymerization produces virgin quality product weaving recycled nylon 6 is assumed tobe equivalent to virgin nylon 6



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Chemical

Chemical use in collection is limited with occasional use of detergents when cleaningpost-consumer waste Processing requires a range of chemicals depending on theparticular depolymerization process method Substances may include aqueous alkalissodium hydroxide sulfuric acid phosphoric acid boric acid metallic sodium and metaloxides (Datye 1991 p 48 Dmitrieva 1986 p 232) Caprolactam purification may bedone with solvents such as toluene or other hydrocarbons The chemistry necessaryfor polymerization is described in the Nylon 6 Material Snapshot Additional substancesused in yarn and weaving processes include spin finishes coning oils titanium oxideantioxidants and heat stabilizers (Datye 1991 p 47)

Physical

The primary inputs are post-consumer recycled products containing nylon such as carpetsfishnets nylon textiles and nylon production waste

Land-use Intensity

The use of post-consumer nylon products reduces the amount of landfill disposal of carpetand pollution of used fishing nets in the ocean Because the primary feedstock of theprocess is post-consumer material the land required to produce recycled caprolactam isrelatively low Land use is limited to manufacturing facilities

Process Outputs

Co-products amp By-products

After depolymerization a pot residue is formed on the sides of the reactor which containscaprolactam and the remains of the catalyst used (Dmitrieva 1986 p 232) Caprolactam

can be extracted from the pot residue through distillation of water or sulfuric acid(Dmitrieva 1986 p 232) The filtrate from this process can also be reapplied in thedepolymerization stage of processing (Dmitrieva 1986 p 233) All unusable by-productsproduced from this process are typically burned in an incinerator and the resulting ash isutilized as a filler in various plastic products (Mihut 2001 p 1469)

Solid Waste

During the sorting and shredding of input post-consumer products such as carpet the facefiber (nylon 6 or 66) is separated from the backing some of which may be recycled whilethe remaining solid waste requires disposal (landfill or incineration for energy recovery)Nylon fibers account for about half of the weight of the post-consumer carpet (Mihut

2001 p 1458) After depolymerization a significant amount of non-volatile waste andby-products remain in the reactor where available these are also incinerated for energyrecovery (Mihut 2001 p 1461) This waste can include titanium oxide inorganic saltstarry products of side reactions antioxidants stabilizers etc (Datye 1991 p 48) Non-hazardous solid waste generation averaged 07 kgkg of recycled nylon yarn (EcoNyl 2011p 15) Weaving waste associated with electricity use is 09 kgkg of woven textile Cradleto gate recycled nylon textile waste is 16 kgkg

Hazardous WasteToxicity

Hazardous waste generation for recycled nylon 6 yarn is approximately 02 kgkg (EcoNyl2011 p 15) These wastes include hazardous impurities removed from the materials in the

depolymerization process as well as hazardous wastes generated in purifying caprolactamand repolymerization



5

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Toxic substances in the processing of recovered nylon 6 wastes include the chemicals usedin depolymerization (aqueous alkalis sodium hydroxide sulfuric acid phosphoric acidboric acid metallic sodium and metal oxides etc) as well as the hydrocarbon solventsthat may be used for caprolactam purification (eg toluene)

Wastewater

The production of 1 kg of recycled nylon yarn results in 0005 kg PO43- eq ofeutrophication potential (substances that contribute to the exhaustion of oxygen inreceiving waters) (EcoNyl 2011 p 14) Wastewater generated from the polymerizationprocess or thermoplastic processing may be further purified to obtain pure caprolactam(Losier et al 1995) This wastewater contains 1-20 of solids of which 1-70 by weightis represented by caprolactam that can be catalytically cracked using aluminum oxide toobtain a more pure concentrated caprolactam (Losier et al 1995)

Emissions

The collection and delivery of nylon waste to processors is a minor contributor to emissions

EcoNyl 2011 p 14) Global warming potential is 78 kg CO 2 eqkg recycled nylon yarn(EcoNyl 2011 p 14) Weaving is 107 kg CO

2 eqkg recycled nylon yarn Cradle to gate

recycled nylon textile is 186 kg CO2 eqkg (Appendix Table D)

Cradle to

recycled nylon

yarn melt spun

Recycled nylon

yarn to fabric

undyed textile

Cradle to

unfinished textile

gate

Energy (MJ) 172 i 229 ii 401

Water (L) 84 i 5 iii 89

Waste (kg) 07 i 09 iii 16

GHG emissions(kg CO

2eq 100 yr)

79 i 107 ii 186

Referencesi EcoNyl 2011 p 13 13 14 15ii van der Velden et al 2014 p 351 Fig 10iii Calculations based on energy data from van der Velden et al (2014) andwater values for electricity generation from Boustead 2005 p 7

Table 1 Inputs And Outputs For 1 Kg Nylon 6

Cradle to

Unfinished Textile

Gate Recycled

Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 66

Energy (MJ) 401 388 399

Water (L) 89 1653 2730

Waste (kg) 16 11 18

GHG emissions

(kg CO2 eq 100 yr)

186 188 185

Table 2 Comparison Of Inputs And Outputs For 1 Kilogram Nylon



6

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Performance And Processing

Functional Attributes And Performance

bull Abrasion resistant 4

bull Excellent Tenacity 5

bull Low moisture absorbency 6

bull Durable 7

bull Elastic 8

bull Resistant to many chemicals 9

Mechanical Attributes

The depolymerization process produces caprolactam which when repolymerized creates nylon 6equivalent to virgin quality nylon (Mihut 2001 p 1460) Depending on the types of catalysts used inthe depolymerization process nylon fibers may have lower fiber strength (Mihut 2001 p 1463)

Processing Characteristics

When using chemical depolyermization post-consumer feedstock can have any variation of molecularweight and chemical contamination without ruining the output caprolactam (Wang 2010 p 139) Thecaprolactam obtained through the depolymerization process is similar to virgin caprolactam in purity(Wang 2010 p 139) The quality of secondary caprolactam is improved when the temperature ofdepolymerization is reduced however a reduction of temperature also lowers the yield of caprolactam

from waste (Dmitrieva 1986 p 232)

During the depolyermization process the yield of pure usable caprolactam is a function of the catalystconcentration and the temperature (Dmitrieva 1986 p 230) For example if sodium hydroxide(NaOH) is being utilized as the catalyst a concentration of 1 can yield 90 pure caprolactam wherecomparatively a concentration of 15 NaOH will only yield 75 output caprolactam (Dmitrieva 1986p 230) Similarly the yield will increase as temperature increases from 230-250oC and decreasesthereafter (Dmitrieva 1986 p 230) When using phosphoric acid as a catalyst the yield of caprolactamis directly proportional to the amount of added catalyst (Dmitrieva 1986 p 231) Studies have shownthat it is possible to obtain reproducible caprolactam yields from the depolymerization of shreddedcarpet of up to 85 (Elam et al 1997 p 994)

4 Akovali 2012 p1355 Ibid6 Ibid7 PlasticsEurope 2014 p8 PlasticsEurope 2014 p9 Akovali 2012 p135

Table 3 Mechanical Attributes Of Recycled Nylon 6

Fiber Properties Nylon 6 Recycled Nylon 6 iii

Melting temp (oC) 225 i 220 iv

Tenacity (gd) 72 i

Tensile Strain () 44 iv

Tensile Strength (kgcm983218) 57 - 62 ii 80 iv

Youngrsquos Modulus (kgcm983218) 5604 i

Water retention () 15 i 16 iv

Referencesi Akovali 2010 pp 123 135ii Kipp 2004 Nylon 6 chartiii A review of the literature did not identify any data on the mechanical attributes ofchemically recycled nylon 6 formulated for textile applications data shown are for achemically recycled nylon 6 for injection molding applicationsiv BASF 2015



7

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The quality of recycled caprolactam can also vary depending on the various additives used in theoriginal consumer product For example if ferric ions are contained in the caprolactam the fiberstrength of resulting recycled nylon 6 will be reduced (Dmitrieva 1986 p 235)If impurities are well controlled the recycled caprolactam can be polymerized into nylon 6 that can bereused for equivalent applications as virgin (USDOE 2001)

Aesthetics

The caprolactam obtained through the depolymerization process is similar to virgin caprolactam inpurity (Wang 2010 p 139) Because of this the majority of products produced from recycled nylon 6have similar qualities to those produced with virgin nylon 6 In general nylon 6 products have goodretention of appearance and can be developed in a wide range of colors (Bunsell 2009 p 219) Itsproperties are similar to polyester though it does wrinkle The fabrics created from filament yarn aresmooth soft and lustrous (Hegde 2004 section 9)

Potential Social And Ethical Concerns

Recycling of nylon 6 avoids the use of benzene and other toxic chemicals required to produce virgin

caprolactam However several chemicals in the recycling process are toxic including the use ofsodium hydroxide and sulfuric acid There is a potential for spills or accidents associated with the useof these chemicals in processing plants

Availability Of Material

The rate of disposal of carpet ranges from 2-3 million tons per year in the US and 4-6 milliontons per year throughout the world (Wang 2010 p 137) Of this carpet 60 is comprised of nylonfibers that are available for recycling (Wang 2010 p 137) Carpet feedstock can be collected fromlandfills or by companies that collect post-consumer carpet directly following the consumer usephase Interface has established a post-consumer nylon recycling organization that gathers post-consumer carpets and nylon fishing nets to use in recycled nylon products (httpwwwinterfacecom

CAen-CAabouttopic=Recycling) There is the potential for producing an estimated 34 million kg ofpost-consumer recycled nylon 6 annually according to Lu (2010 p 69) Aquafil is a supplier based innorthern Italy with a depolymerization facility in Slovenia that produces 100 recycled nylon under thebrand name EcoNyl (httpwwwEcoNylcom) Around 50 of the recycled content in EcoNyl is fromrecycled post-consumer carpets and fishing nets


Nylon specific recycling certifications do not exist Scientific Certification Systems has a recycledcontent certification (httpscscertifiedcomdocsSCS_STN_RecycledContent_V4-1_121809pdf ) andthe Textile Exchange Recycled Claim Standard is also available (httptextileexchwpenginecomwp-contentuploads201601TE-Recycled-Claim-Standard-v1pdf )

Cost Of TextileReprocessed post-consumer nylon pellets cost around $040 per lb over a decade ago (Lave et al1998 p 121) Currently post-industrial nylon 6 pellets cost between $079-081 per pound (ResourceRecycling 2014 p 1) Prices for recycled nylon tend to be lower or on par with virgin nylon andfluctuate in conjunction with demand and imports (Resource Recycling 2014 p 1)



8

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Questions To Ask When Sourcing This Material

Q Is the recycled nylon mechanically or chemically recycled

For chemically recycled nylon 6 material

Q How are by-products and wastes managed from the depolymerization and caprolactam purificationprocesses

Q Is the nylon 6 polymerized from 100 recycled caprolactam

Q Are ferric ions found in the post-consumer nylon product



9

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Depolymerization

Distillation amp Purification

Nylon 6 Polymerization

Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali

Fuel-relatedEmissions

1 kg Undyed RecycledNylon 6

Water

Transportation

GreenhouseGas Emissions

Energy

Figure 1 System Diagram Of Chemically Recycled Nylon 6

Post-consumer NylonCollection

Feedstock Sorting

Mechanical Shredding

Steam

Catalyst egPhosphoric Acid

Transportation

Transportation



Excess Caprolactam

Pot Residue

Contaminants FromCarpet

Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

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Appendix

Calculations For Acrylic

EnergyEcoNyl Yarn i FDY raw white(MJ) Textured yarn raw white(MJ) Average(MJ)

Cradle to yarn ii 1740 1700 1720

Weaving (70 dtex) iii 2290

Cradle to Gate Undyed Textile Total 4010

Notes Referencesi All values related to EcoNyl yarn include carpet collection and grinding depolymerization re-polymerization spinning and texturizingwrappingii EcoNyl 2011 p 13iv van der Velden p 351

Water Unit Quantity

Cradle to yarn water use (average of EcoNyl yarns) i L 84

Weaving water use

Weaving energy ii MJkg 229

Water use per MJ factor from electricity production iii LMJ 0022

Calculated water use Lkg 50

Cradle to Gate Undyed Textile Total Lkg 890

Referencesi EcoNyl 2011 p 13ii van der Velden 2014 p 351iii Plastics Europe 2005 p 7

Table A Energy For Recycled Nylon 6

Table B Water For Recycled Nylon 6

Waste Unit Quantity

Cradle to yarn waste (average of EcoNyl yarns) i kg 07

Weaving waste useWeaving energy ii MJkg 229

Waste per MJ factor from electricity production iii kgMJ 0004

Calculated waste kgkg 09

Cradle to Gate Undyed Textile Total kgkg 16


Table C Waste For Recycled Nylon 6



11

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GWP FDY raw white

(MJ)

Textured yarn raw white

(MJ)

Average

(MJ)

Cradle to yarn from fossil fuels i 74 73 74

Cradle to yarn from bio sources i 04 07 05

Weaving (70 dtex) ii 107


Referencesi EcoNyl 2011 p 14ii van der Velden 2014 p 351

Table D GWP For Recycled Nylon 6



12

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References

Akovali Guumlneri (2012) Advances in Polymer Coated Textiles Smithers Rapra Technology Retrieved from httpappknovelcomwebtocvcidkpAPCT0001viewerTypetocroot_slugadvances-in-polymer-coatedurl_slugadvances-in-polymer-coatedb-q=Advances20in20Polymer20Coated20Textilesampsort_on=defaultampb-subscription=TRUEampb-group-by=trueampb-search-type=tech-referenceampb-sort-on=default

BASF (2015) Nypel 2314 HS BK6 Polyamide 6 Retrieved from httpiwwwplasticsportalcomproductsdspdfphptype=isoampparam=Nypel+2314+HS+BK6

Braun M Levy A B amp Sifniades S (1999) Recycling Nylon 6 Carpet to Caprolactam Polymer-Plastics Technology andEngineering 38(3) 471-484

Bunsell A R (2009) Handbook of Tensile Properties of Textile and Technical Fibres Woodhead Publishing (p197-204)Retrieved from httpappknovelcomwebtocvcidkpHTPTTF03viewerTypetocroot_slughandbook-tensile-propertiesurl_slughandbook-tensile-propertiesb-q=Handbook20of20Tensile20Properties20of20Textile20and20Technical20Fibresampsort_on=defaultampb-subscription=TRUEampb-group-by=trueampb-search-type=tech-referenceampb-sort-on=default

Datye K V (1991) Recycling Processes and Products in Nylon 6 Fiber Industry Indian Journal of Fibre amp Textile Research 16 46Retrieved from httpnoprniscairresinbitstream123456789192071IJFTR2016(1)2046-51pdf

Ditty S (2013) From waste to Wear ECONYL Recycled Nylon is Cleaning Up our Seas The Ethical Fashion Source IntelligenceRetrieved from httpsourceethicalfashionforumcomarticlefrom-waste-to-wear-EcoNyl-recycled-nylon-is-cleaning-up-our-seas

Dmitrieva L A Speranskii A A Krasavin S A amp Bychkov Y N (1986) Regeneration of ε-Caprolactam from Wastes in theManufacture of Polycaproamide Fibres and Yarns Fibre Chemistry Vol 17(4) 229-241

Duch M and Allgeier A (2007) Deactivation of Nitrile Hydrogenation Catalysts New Mechanistic Insight from a Nylon RecycleProcess Applied Catalysis A General Vol 318 190ndash198

EcoNyl (2011) Environmental Product Declaration for EcoNyl Nylon Textile Filement Yarn Aquafil synthetic fibers and polymersCPC code 264 July 1st 2011 Retrieved from httpgryphonenvirondeccomdatafiles68143epd278pdf

Elam C C Evans R J amp Czernik S (1997) An Integrated Approach to the Recovery of Fuels and Chemicals from Mixed WasteCarpets through Thermocatalvic Processing Retrieved from httpwebanlgovPCSacsfuelpreprint20archiveFiles42_4_LAS20VEGAS_09-97_0993pdf

Hegde R Raghavendra Dahiya Atum amp Kamath M G (2004) Nylon Fibers Retrieved from httpwwwengrutkedumsepagesTextilesNylon20fibershtm

Interface (nd) ldquoCarpet to Carpet Recyclingrdquo Retrieved from httpwwwinterfacecomUSen-USaboutmodular-carpet-tileReEntry-20

Lave L Conway-Schempf N Harvey J Hart D Bee T amp MacCracken C (1998) Recycling Postconsumer Nylon CarpetJournal of Industrial Ecology 2(1) 117-126

Lozano-Gonzaacutelez et al (2000) PhysicalndashMechanical Properties and Morphological Study on Nylon-6 Recycling by InjectionMolding Journal of Applied Polymer Science Vol 76 851ndash858

Losier T P Johnson D R Fuchs H Neubauer G amp Ritz J (1995) US Patent No 5458740 Washington DC US Patentand Trademark Office Retrieved from httpswwwgooglecompatentsUS5458740



13

copy 2016

Lu D (2010) Environmental Life Cycle Driven Decision Making in Product Design (Doctoral dissertation Georgia Institute ofTechnology) Retrieved from httpssmartechgatechedubitstreamhandle185334843di_lu_201008_phdpdf

Mandoki J W (1986) US Patent No 4605762 Washington DC US Patent and Trademark Office Retrieved from httpswwwgooglecompatentsUS4605762

Mather Robert R Wardman Roger H (2011) Chemistry of Textile Fibres Royal Society of Chemistry Retrieved from httpappknovelcomwebtocvcidkpCTF00001viewerTypetocroot_slugchemistry-of-textile-fibres

Mihut C Captain D K Gadala-Maria F amp Amiridis M D (2001) Review Recycling of Nylon from Carpet Waste PolymerEngineering amp Science 41(9) 1457-1470

Patil D and Madhamshettiwar S (2014) ldquoKinetics and Thermodynamic Studies of Depolymerization of Nylon Waste byHydrolysis Reactionrdquo Journal of Applied Chemistry Vol 2014 Article ID 286709 8 pages Retrieved from httpdxdoiorg1011552014286709

Plastics Europe (2005) Electricity Production (on-site) Eco-Profiles of the European Plastics Industry March Retrieved from

httpwwwplasticseuropeorgplastics-sustainability-14017eco-profilesbrowse-by-listaspx Retrieved from httpwwwplasticseuropeorgplastics-sustainability-14017eco-profilesbrowse-by-listaspx

Plastics Europe (2014) Polymide 6 (PA6) Eco-Profiles and Environmental Product Declarations of the European PlasticsManufacturers February 2014 Retrieved from httpwwwplasticseuropeorgplastics-sustainability-14017eco-profilesbrowse-by-listaspx

Resource Recycling (2014) PetroChem Wire Nylon 6 Price Falls on Weak Demand December 18 2014 Retrieved from httpresource-recyclingcomnode5518

US Department of Energy Office of Industrial Technologies (2001) Nylon 6 Recycling New Process to Recover and ReuseNylon Waste Retrieved from httpwww1eereenergygovmanufacturingresourceschemicalspdfsnylonpdf

US Environmental Protection Agency (USEPA) (2015) Carpet The Environmental Protection Agency WARM Version 13Retrieved from httpepagovepawasteconservetoolswarmpdfsCarpetpdf

van der Velden N M Patel M K amp Vogtlaumlnder J G (2014) LCA Benchmarking Study on Textiles Made of Cotton PolyesterNylon Acryl or Elastane The International Journal of Life Cycle Assessment 19(2) 331-356

Wang Y (2006) Carpet Recycling Technologies Recycling in Textiles 58-70 Chicago Retrieved from httpwwwprismgatechedu~yw6FiberrecyclingRecycling20in20Textiles20YWang20Ch6pdf

Wang Y (2010) Fiber and textile waste utilization Waste and biomass valorization 1(1) 135-143 Retrieved from httpwww

localnetabertayacukmediaFibre_Waste_Textile_Processing_YoujiangWangpdf



This guide is one of 29 Material Snapshots produced by Textile Exchangein 2015 with financial support from VF Corporation and in collaborationwith Brown and Wilmanns Environmental LLC They are an extension ofthe original series released by TE in 2014

The content of this snapshot is designed to provide general informationonly While every effort has been made to ensure that the informationprovided is accurate it does not constitute legal or other professionaladvice Textile Exchange cannot be held responsible for the contentsof this snapshot or any subsequent loss resulting from the use of theinformation contained herein

As a continual work in progress this snapshot will be reviewed on aregular basis We invite readers to provide feedback and suggestions forimprovement particularly with regards to data where new and improvedsources are likely to emerge over time

For more information please email SolutionsTextileExchangeorg orvisit httptextileexchangeorgpublicationsmaterial-snapshots

Version 1 - January 2016

All rights reserved Textile Exchange copy 2016

Proudly sponsored byVF Corporation

Developed by

Prepared in collaboration withBrown and Wilmanns Environmental LLC



2

copy 2016

Unit Process Descriptions

Raw Material Sourcing

A wide range of nylon waste is generated that can be collected processed and recycled into newnylon materials A significant barrier to efficient collection and recycling is the diversity of nylonmaterials ndash eg nylon 6 nylon 66 nylon 610 nylon 11 nylon 12 etc Nylon collection and recycling

is most cost efficient when there are large volumes of relatively homogenous waste material (egcarpet) Consequently collection and recycling is mostly nylon 6 and nylon 66 waste carpet withadditional waste from virgin nylon production (Gupta and Kothari 1997 p 616) fishing nets (Coplare2012) and textiles (pre- and post-consumer) None of these materials are collected via multi-materialresidential curbside collection programs Rather these materials are typically obtained throughrelationships with waste generators or takeback programs such as Interfacersquos ReEntry program(Interface nd ldquoCarpet to Carpet Recyclingrdquo)

Processing

Alternative methods for recycling waste nylon materials and products include mechanical extraction(also called melt processing) and various methods of depolymerization followed by repolymerization

(Wang 2006 pp 2-5) Processors typically choose a method that results in a specified level of outputquality for a given waste nylon source Relatively clean nylon can be depolymerized to provide inputsto polymerization of virgin quality nylon conversely nylon with some contamination can be meltprocessed into lower quality nylon (Mihut et al 2001 p 1458)

Mechanical processing1 involves cleaning the collected raw recyclate shredding it into small piecesdensifying the shredded material to increase uniformity melting the material and extruding the meltedmaterial to either form pellets or filaments Pellets are packaged and shipped to customers that usemechanical means such as injection molding or extrusion to form a wide variety of nylon products

Filaments are formed (whether directly from shredded nylon or from pellets) by extruding the meltthrough a spinnerette and drawing twisting and winding the resulting fibers that can then beprocessed further into yarn (EOS nd ldquoRecycling Nylon CarpetndashMelt Processingrdquo) Carpets that are

shredded and melted without segregating the nylon from the backing material generally requirea variety of additives to enhance compatibility of the mixed polymers Even when segregatedmechanically recycled nylon generally results in a reduction in functional and performance properties(Lozano-Gonzaacutelez et al 2000) Nylon 66 is often mechanically recycled whereas nylon 6 iscommonly chemically recycled and can easily be processed back into the same products from whichthe original recovered nylon originated (Zeftron nd ldquoReclamation amp Recyclingrdquo)

Due to its relatively high value compared with other polymers and because it easily oxidizes instorage resulting in gels when melt processed (Datye 1991 p 47) nylon 6 is a good candidate forchemical recycling via depolymerization (Wang 2006 p 2 EOS nd ldquoNylon Carpet RecyclingndashDepolymerizationrdquo) Similar to mechanical recycling carpets go through a process of sorting todetermine polymer type shredding and separation using density techniques of the face fiber (the

nylon 6) from the backing (synthetic polymers andor bio-based materials) (Lu 2010 pp 38-39) Theseparated nylon 6 is then batch processed in a depolymerization reactor

The reactor is maintained as a nitrogen-free environment while the nylon 6 is treated with super-heated steam (Wang 2010 p 139) at elevated pressure (410-450 kPa) and temperature (250-340oC)(Braun et al 1999 pp 471 476 Dmitrieva 1986 p 231) to produce an aqueous solution of 10-50caprolactam (Gupta and Kothari 1997 pp 617-618) Catalysts such as an alkali (sodium hydroxide)metallic sodium metal oxides or phosphoric acid and its salts are used to increase caprolactamyields although they result in differing levels of purity (Gupta and Kothari 1997 pp 617-618 Dmitrieva1986 p 230)

The aqueous solution of caprolactam can be contaminated with additives used in the original productsuch as dyes lubricant preparations and various fillers (Dmitrieva 1986 p 234) To remove impurities

the recovered caprolactam may be distilled in the presence of an aqueous alkali at a temperature of100-150oC (Dmitrieva 1986 p 238)

1 Mechanical processing generally includes a melting process and the terms are used interchangeably



3

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Process Inputs

Energy


Water






4

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Chemical


Physical


Land-use Intensity


Process Outputs




Solid Waste








5

copy 2016


Wastewater


Emissions





Cradle to

recycled nylon

yarn melt spun

Recycled nylon

yarn to fabric

undyed textile

Cradle to

unfinished textile

gate

Energy (MJ) 172 i 229 ii 401



GHG emissions(kg CO

2eq 100 yr)

79 i 107 ii 186



Cradle to

Unfinished Textile

Gate Recycled

Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 66

Energy (MJ) 401 388 399

Water (L) 89 1653 2730

Waste (kg) 16 11 18

GHG emissions

(kg CO2 eq 100 yr)

186 188 185




6

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bull Durable 7

bull Elastic 8












Tenacity (gd) 72 i








7

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Aesthetics













8

copy 2016









9

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Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

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GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

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References


















13

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Developed by




3

copy 2016






Process Inputs

Energy


Water






4

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Chemical


Physical


Land-use Intensity


Process Outputs




Solid Waste








5

copy 2016


Wastewater


Emissions





Cradle to

recycled nylon

yarn melt spun

Recycled nylon

yarn to fabric

undyed textile

Cradle to

unfinished textile

gate

Energy (MJ) 172 i 229 ii 401



GHG emissions(kg CO

2eq 100 yr)

79 i 107 ii 186



Cradle to

Unfinished Textile

Gate Recycled

Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 66

Energy (MJ) 401 388 399

Water (L) 89 1653 2730

Waste (kg) 16 11 18

GHG emissions

(kg CO2 eq 100 yr)

186 188 185




6

copy 2016






bull Durable 7

bull Elastic 8












Tenacity (gd) 72 i








7

copy 2016


Aesthetics













8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




4

copy 2016

Chemical


Physical


Land-use Intensity


Process Outputs




Solid Waste








5

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Wastewater


Emissions





Cradle to

recycled nylon

yarn melt spun

Recycled nylon

yarn to fabric

undyed textile

Cradle to

unfinished textile

gate

Energy (MJ) 172 i 229 ii 401



GHG emissions(kg CO

2eq 100 yr)

79 i 107 ii 186



Cradle to

Unfinished Textile

Gate Recycled

Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 66

Energy (MJ) 401 388 399

Water (L) 89 1653 2730

Waste (kg) 16 11 18

GHG emissions

(kg CO2 eq 100 yr)

186 188 185




6

copy 2016






bull Durable 7

bull Elastic 8












Tenacity (gd) 72 i








7

copy 2016


Aesthetics













8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




5

copy 2016


Wastewater


Emissions





Cradle to

recycled nylon

yarn melt spun

Recycled nylon

yarn to fabric

undyed textile

Cradle to

unfinished textile

gate

Energy (MJ) 172 i 229 ii 401



GHG emissions(kg CO

2eq 100 yr)

79 i 107 ii 186



Cradle to

Unfinished Textile

Gate Recycled

Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 6

Cradle to

Unfinished

Textile Gate

Virgin Nylon 66

Energy (MJ) 401 388 399

Water (L) 89 1653 2730

Waste (kg) 16 11 18

GHG emissions

(kg CO2 eq 100 yr)

186 188 185




6

copy 2016






bull Durable 7

bull Elastic 8












Tenacity (gd) 72 i








7

copy 2016


Aesthetics













8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




6

copy 2016






bull Durable 7

bull Elastic 8












Tenacity (gd) 72 i








7

copy 2016


Aesthetics













8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




7

copy 2016


Aesthetics













8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




8

copy 2016









9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




9

copy 2016

Depolymerization



Melt Spinning

Solidifying

Drawing

Winding

Heat Setting

Weaving

Transportation

Post-consumer Nylon

Aqueous Alkali



Water

Transportation


Energy



Feedstock Sorting


Steam


Transportation

Transportation



Excess Caprolactam

Pot Residue


Aqueous Solution

Solid Waste

Process FlowInputs

Outputs



10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




10

copy 2016

Appendix







Water Unit Quantity


Weaving water use








Waste Unit Quantity










11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




11

copy 2016

GWP FDY raw white

(MJ)


(MJ)

Average

(MJ)









12

copy 2016

References


















13

copy 2016

























Developed by




12

copy 2016

References


















13

copy 2016

























Developed by




13

copy 2016

























Developed by











Developed by


recycled nylon 6

Documents