Recycled plastics tam sim no yog ib lub ntsiab lus hauv kev ntim khoom. Cov neeg xav txo cov pov tseg. Txoj cai lij choj xav kom cov tuam txhab lag luam rov qab ntim cov khoom qub. Lub tuam txhab cog lus tias yuav siv cov khoom siv rov ua dua tshiab. Yog li cov tuam ntxhab tau sim ntau npaum li cas cov yas rov ua dua tshiab lawv tuaj yeem muab tso rau hauv tshuab. Qhov no suav nrog cov tshuab hnab yas. Cov lus teb yog yooj yim: ntau tshaj li kaum xyoo dhau los. Tab sis qhov ntawd tseem nyob deb ntawm ntau lub hom phiaj.
Qhov sib txawv ntawm cov lus cog tseg loj thiab lub tshuab ua tau dab tsi tsim nyog yuav tsum tau ua tib zoo kawm. Recycled plastics ua rau muaj teeb meem ntau. Lawv hnav lub tshuab qis dua. Lawv txo cov zis zoo. Lawv hloov qhov kev ruaj ntseg ntawm cov txheej txheem. Lawv undermine cov khoom sib xws. Nkag siab txog cov kev txwv no tsis tau txhais hais tias peb yuav tsum tsis txhob siv cov khoom siv rov ua dua tshiab. Qhov ntawd txhais tau tias peb yuav tsum siv lawv hauv txoj kev ntse.
1. Cov teeb meem kev sib kis Upstream ntawm lub tshuab
Txhua lub polymers tau sau, txheeb, ntxuav thiab granulated ua ntej nkag mus rau hauv lub hnab ntim khoom yas. Txhua kauj ruam ntxiv qhov sib txawv tsis pom nyob rau hauv cov resin tshiab.
Tshaj tawm -cov neeg siv khoom siv rov ua dua polyethylene (PCR-PE) yog cov khoom tseem ceeb hauv cov hnab ntim khoom siv rov ua dua tshiab. Tab sis nws tsis tshua muaj hom huv. Nws sib xyaw LDPE zaj duab xis, siab - ntom polyethylene (HDPE) fwj, polypropylene lub kaus mom, daim ntawv lo, kua nplaum thiab cov khoom noj me me. Txawm tias tom qab ntxuav thiab sorting, mechanical recycling tsis ua kom nws ntshiab li cov ntaub ntawv tshiab.
Yog li, nyob rau hauv kev xyaum, regenerated hais muaj ntau yam sib txawv ntawm:
- Moisture: Yog hais tias cov khoom rov qab tsis qhuav zoo, npuas, kab thiab qhov chaw tsis zoo tuaj yeem tsim rau ntawm zaj duab xis. Thaum LDPE tshiab nkag mus rau hauv extruder, nws feem ntau muaj tsawg dua 200 ppm dej. Txawm li cas los xij, ntau PPE yuav rov siv dua tom qab noj yog tias nws tsis qhuav kom zoo.
- Cov khoom tsis yog-PE: Polypropylene thiab lwm yam polymers sib txawv tuaj yeem tsim qhov chaw tsis muaj zog hauv zaj duab xis. Txawm hais tias lawv tsawg dua 1% ntawm tag nrho qhov hnyav, lawv tuaj yeem ua rau muaj qhov tsis muaj zog hauv zos. Cov pob no txo qhov cuam tshuam ntawm dart poob.
- Remnant Xim thiab Ink: Cov xim ntawm cov xim thiab tus cwj mem los ntawm cov ntim qub ua rau zaj duab xis zaum kawg tsis tshua muaj xim. Tej yam ntuj tso los yog lub teeb- cov hnab xim yog qhov nyuaj tshwj xeeb los ntxuav thaum siv cov khoom siv rov ua dua tshiab.
2. Rheological Variability thiab nws ua li cas rau Extrusion Stability
Txhua lub hnab yas lub hnab ntim khoom siv uas siv cov tshuab cua tshuab yuav tsum muaj cov dej ntws tsis tu ncua ntawm cov polymer rau hauv lub extruder. Melt Flow Index (MFI) yog ib qho kev ntsuas ntawm qhov yooj yim polymers ntws raws li qhov hnyav. Nws yog qhov chaw tseem ceeb tshaj plaws kom ua npuas ruaj khov thiab zaj duab xis tuab tuab.
LDPE tshiab feem ntau yog tsim nyob rau hauv qhov nqaim MFI, feem ntau yog 0.3-2.0 g/10min nyob ntawm kev siv. Txawm li cas los xij, MFI hloov pauv ntawm cov neeg siv khoom siv rov qab siv dua polyethylene feem ntau yog ± 30 - 50% txawm tias tom qab siv ib zaug. Qhov no yog vim cov khoom siv rov ua dua tshiab yog tsim los ntawm kev sib xyaw ntawm cov resin los ntawm cov tuam txhab sib txawv nrog cov qib sib txawv.
Thaum MFI hloov pauv thaum lub sijhawm ua haujlwm, nws yog ib qho tsim nyog yuav tsum tswj hwm qhov kev hloov pauv hloov pauv raws li cov ntsia hlau ceev. Lub siab hauv qhov sib txawv tuag hloov. Frost kab qhov siab qhov siab hloov. Tag nrho cov kev hloov no cuam tshuam rau zaj duab xis thickness. Dav yuav nyob twj ywm ± 3 - 5% ntawm cov khoom siv raw khoom ruaj khov. Cov ntsiab lus dej ntawm cov khoom siv rov ua dua yog ± 10 - 15% nrog cov khoom siv tsis zoo. Qhov no ncaj qha cuam tshuam rau lub zog thiab sealing zoo ntawm lub hnab ntaub.
Cov neeg ua haujlwm sim daws qhov teeb meem no los ntawm kev ua kom cov ntsia hlau rov qab siab lossis hloov pwm kub. Txawm li cas los xij, muaj kev txwv ntau npaum li cas lawv tuaj yeem hloov kho thaum pub zaub mov hloov pauv ntau ntawm ib pawg mus rau lwm qhov.
3. Thermal Degradation thiab Molecular Weight Reduction
Polyethylene decomposes los ntawm tshav kub thiab oxygen txhua zaus nws ua tiav. Thaum lub sij hawm thawj daim nyias nyias tsim, lub polymer yog rhuab ib zaug. Thaum cov neeg kho tshuab rov qab, lawv tau rov ua dua thaum lub sij hawm granulation. Cov khoom siv rov ua dua yog cua sov peb zaug thaum lawv nkag mus rau hauv lub hnab yas tshuab.
Txhua kauj ruam ntawm cua sov ua rau cov saw hlau tawg. Qhov no txhais tau tias ntev polymer chains tuaj yeem tawg mus rau hauv cov khoom luv luv. Qhov no txo qis molecular hnyav. Qhov no yuav txo tau lub zog tensile thiab elongation thaum tawg. Txhua qhov poob yog txawv. Ntau yam nyob ntawm cov stabilizers hauv cov khoom qub. Tab sis tag nrho cov nyhuv yog ntsuas tau.
Kev tshawb fawb ntawm mechanically recycled LDPE qhia tias tensile lub zog txo los ntawm 15-30% piv rau cov ntaub ntawv tshiab tom qab ob los yog peb reprocessing cycles. Feem ntau, cov pob txha elongation txo qis dua lub zog tensile.
Ntxiv cov antioxidant stabilizers rau lub compound tuaj yeem pab txo qhov kev puas tsuaj no. Tab sis lawv siv ntau dua. Lawv xav tau tus nqi raug. Hauv cov txheej txheem, lwm yam uas yuav tsum tswj tau ntxiv.
4. Tshuab Hnav thiab Kev Kho Kom Zoo Dua
Cov khoom siv rov ua dua tshiab tsis zoo hnav cov khoom extruder sai dua li cov ntaub ntawv tshiab. Qhov no tau tshwm sim hauv cov hauv qab no:
Abrasive hnav ntawm cov ntsia hlau thiab cov phom phom: calcium carbonate ntawm cov xuab zeb, cov iav fragments thiab daim ntawv lo yog zoo li cov ntawv xuab zeb ntawm cov ntsia hlau thiab cov phom phom. Ntawm cov kab tshiab, cov studs tuaj yeem ua haujlwm tsis tu ncua rau ntau xyoo. Nrog cov khoom siv qias neeg rov ua dua tshiab, lub sijhawm yuav luv dua. Nws nyob ntawm seb muaj av ntau npaum li cas thiab nyuaj npaum li cas cov ntsia hlau thiab cov thoob.
Corrosion hnav ntawm cov kab mob halogenated: Yog tias PVC nkag mus (thaum kev sib cais tsis tiav), nws tso tawm hydrochloric acid ntawm kev ua haujlwm kub. Hydrogen chloride tawm tsam lub thoob hlau thiab pwm nto. Tsuas yog 0.1-0.5% PVC.
daim di ncauj buildup (Pwm daim di ncauj Slobber): me me tawg molecules thiab residues nyob rau hauv recyclable cov ntaub ntawv uas accumulates nyob rau hauv daim di ncauj. Qhov ntawd txhais tau tias muaj kev tu ntau dua. Ntawm cov kab tshiab, cov hnab ntim tau tsim thiab ntxuav txhua qhov kev hloov pauv. Ntawm cov kab uas muaj ntau cov khoom siv rov ua dua tshiab thiab cov khoom siv tsis zoo, lawv yuav tsum tau ntxuav txhua teev lossis ntau dua. Qhov no ncaj qha txo lub sijhawm khiav ntawm lub tshuab.
Cov teeb meem kev saib xyuas no nce tus nqi ib kilogram ntawm cov zis. Thaum xav txog tag nrho cov nqi ntawm kev siv cov khoom siv rov ua dua tshiab, tus nqi no feem ntau tsis txaus.
5. Zaj duab xis Optical thiab Mechanical Quality Thresholds
Cov tshuab hnab yas tuaj yeem tsim los ntawm kev sib xyaw ntawm cov khoom siv tshiab thiab siv dua tshiab. Tab sis raws li tus nqi ntawm cov khoom siv rov ua dua tshiab, qhov zoo mus qis dua thiab qis dua. Los ntawm kev paub txog kev lag luam, qhov kev txwv ntawm cov khoom lag luam tus qauv yog 30-50% PCR. Tsis tas li ntawd, qhov zoo pib poob qis, tsuav yog cov khoom siv rov ua dua tshiab yog huv thiab muaj MFI ruaj khov.
Nyob rau hauv tas li ntawd, ntau yam zoo qhia tau phem dua:
- Dart Drop Impact Strength (ASTM D1709): Qhov no yog qhov tseem ceeb ntawm kev nyab xeeb lub hnab ntim lub zog. Vim yog cov gel thiab qis molecular hnyav, nws txo qis nrog PCR ntau dua. Lub hnab yuav tawg yog tias siv qis dua qhov txwv. Qhov no tuaj yeem ua rau cov neeg siv khoom tsis txaus siab thiab teeb meem kev cai lij choj.
- Haze thiab clarity: Recycled PE yog yuav luag ib txwm muddier dua tshiab. Rau cov hnab uas yuav tsum tau muab tshem tawm-xws li cov hnab tsim, hnab ris tsho lossis cov hnab ntim khoom tshem tawm-PCR siab tsis ua raws li cov khoom xav tau.
- Kev sib xyaw ua ke ntawm lub zog sealing: Cov seams yuav thinner vim muaj av nyob hauv qhov chaw foob. Nrog rau qhov nce ntawm PCR, qhov kub thiab txias ntawm thermal foob tau ntau thiab nqaim. Qhov no txhais tau tias xav tau kev tswj qhov kub thiab txias dua. Ntau lub hnab qub tsim ua tsis tau li ntawd.
6. Kev tswj hwm thiab kev sau npe txwv
Ntxiv nrog rau kev txwv lub cev, cov neeg tsim khoom siv lub hnab ntim khoom siv rau cov khoom siv rov ua dua tshiab yuav tsum tau ua raws li cov cai hloov pauv. Cov kev cai no cuam tshuam li cas lawv xav txog cov khoom kawg.
Hauv Tebchaws Meskas, FTC's Green Guides (16 CFR Part 260) tau teeb tsa cov cai rau kev thov ib puag ncig, suav nrog "cov ntsiab lus rov ua dua tshiab" cov ntawv. Kev thov yuav tsum tau rov qab los ntawm cov ntaub ntawv pov thawj ntawm qhov tseeb PCR feem pua. Lawv tsis tuaj yeem sib cav txog qhov txiaj ntsig ntawm ib puag ncig loj dua li tuaj yeem ua pov thawj.
Hauv European Union, European Green Claims Directive (qhia nyob rau xyoo 2023 thiab tseem tab tom txhim kho) yuav tsum qhia cov cai nruj dua rau kev rov ua dua cov ntsiab lus thov. Qhov no suav nrog -kev tshuaj xyuas thib peb. Cov neeg tsim khoom ntawm hybrid recycled cov ntaub ntawv yuav tsum tau sau ntawv thiab taug qab tag nrho cov txheej txheem rau cov khoom siv rov ua dua tshiab.
Qhov no ntxiv cov haujlwm hauv chaw ua haujlwm. Cov neeg tsim lub hnab me me-uas suav rau feem ntau ntawm lub ntiaj teb cov neeg tsim lub hnab- tuaj yeem pom lub nra hnyav heev piv rau cov khoom siv me me uas lawv muaj tiag tiag.
7. Yuav tsum muaj kev vam meej li cas tiag
Nws muaj peev xwm khiav tau cov ntaub ntawv siv dua tshiab los ntawm cov khoom siv hnab yas. Tab sis nws yuav siv nyiaj thiab ua haujlwm hauv ntau qhov chaw ntawm lub cev, tsis yog lub tshuab xwb.
Kev tswj cov khoom noj khoom haus zoo: Tsim kom muaj cov cai meej rau kev pub noj (MFI ntau yam, txwv tsis pub ya raws thiab av) thiab sim txhua pawg ua ntej siv. Yog tsis muaj qhov ntawd, kev kho lub tshuab yog qhov tshuaj tiv thaiv, tsis yog qhov kev npaj.
Compatibilizers thiab stabilizer tej pob khoom: Cov cua txias tshwj xeeb tuaj yeem pab txo lub zog poob thiab txo cov cua sov puas los ntawm cov khoom siv rov qab. Cov no yog muag los ntawm cov neeg muag khoom tab sis xav tau cov cuab yeej cuab tam thiab kim dua.
Kev hloov kho tshuab: Screws rau cov ntaub ntawv uas hloov tuab, txhim kho qhov kub thiab txias thiab txhim kho pwm tuaj yeem ua rau qhov tseeb PCR txwv. Cov tshuab qub yuav xav tau cov khoom tshiab los ua haujlwm ntawm qib zoo tshaj 30% rov ua dua tshiab.
Xaus
Cov kev txwv ntawm cov tshuab hnab yas siv cov khoom siv rov ua dua tshiab yog qhov tseeb thiab meej: cov khoom siv tsis sib xws, cov dej ntws tsis sib xws, siv lub tshuab nrawm dua, nqaim ntau yam thiab kev tswj hwm tshiab. Tsis muaj qhov no txhais tau tias peb yuav tsum tsis txhob siv cov khoom siv rov ua dua tshiab. Lawv lub ntsiab lus yog dab tsi peb yuav tsum tau mus rau nws nrog kev ceev faj, es tsis yog tsuas yog kho feem pua cov hom phiaj raws li kev lag luam thawv los kuaj.
Cov tuam txhab lag luam uas tau ua tiav tiag tiag yog cov uas pom cov ntsiab lus rov ua dua tshiab raws li qhov teeb meem ntawm cov khoom siv engineering, tsis yog ib qho teeb meem ntawm kev yuav thiab sib pauv. Qhov ntawd txhais tau hais tias kev nqis peev hauv cov ntaub ntawv cov cai, taug qab cov txheej txheem thiab kho cov tshuab raws li xav tau. PCR los ntawm 20% mus rau 50% tsis yog ib txoj kab ncaj nraim. Tab sis nws tuaj yeem ua tiav nrog lub hauv paus technical.
Cov ntaub ntawv:
- Ellen MacArthur Foundation. Kev lag luam yas tshiab: Rov xav txog yav tom ntej ntawm cov yas . 2016.
- Giles, Harold F., Wagner, John R., Mount, Eldridge M. Extrusion: Phau Ntawv Qhia Txog Kev Ua Haujlwm Zoo thiab Phau Ntawv Qhia. William Andrew Publ., 2005.
- Hopewell, Jefferson, Dvorak, Robert, Kosior, Edward. "Plastics Recycling: Challenges and Opportunities." Philosophical Transactions ntawm Royal Society B, Vol. 364, 2009.
- Dawb, James L., Potente, Helmut. Ntsia Hlau Extrusion: Science thiab Technology. Hanser Gardner Publications, 2003.
- ASTM International. ASTM D1709: Standard Test Methods for Impact Resistance of Plastic Film by the Free -Dalling Dart Method. Tsab ntawv tam sim no.
- US Federal Trade Commission. Cov Lus Qhia rau Kev Siv Cov Kev Cai Lij Choj Environmental (Green Guides), 16 CFR Part 260. Revised 2012.
