1. Chiyambi
EVA ndi chidule cha ethylene vinyl acetate copolymer, polima ya polyolefin. Chifukwa cha kutentha kwake kotsika kosungunuka, kusinthasintha kwabwino, polarity ndi zinthu zopanda halogen, ndipo imatha kugwirizana ndi ma polima osiyanasiyana ndi ufa wa mchere, zinthu zingapo zamakanika ndi zakuthupi, mphamvu zamagetsi ndi magwiridwe antchito, komanso mtengo wake si wokwera, kupezeka kwa msika ndikokwanira, kotero zonse monga zinthu zotetezera chingwe, zitha kugwiritsidwanso ntchito ngati zodzaza, zophimba; zitha kupangidwa kukhala zinthu za thermoplastic, ndipo zitha kupangidwa kukhala zinthu zolumikizirana za thermosetting.
Magwiritsidwe ntchito osiyanasiyana a EVA, okhala ndi zotchingira moto, amatha kupangidwa kukhala chotchingira mafuta chopanda utsi wambiri kapena chotchingira mafuta cha halogen; sankhani kuchuluka kwa VA mu EVA chifukwa zinthu zoyambira zitha kupangidwanso kukhala zinthu zosagwira mafuta; sankhani index yosungunuka ya EVA yapakati, onjezerani kuwirikiza kawiri mpaka katatu kuposa kudzazidwa kwa zotchingira moto za EVA zomwe zingapangidwe kuti zigwire ntchito bwino komanso mtengo wa zinthu zotchingira mpweya (zodzaza) bwino.
Mu pepalali, kuchokera ku kapangidwe ka EVA, kuyambitsidwa kwa kugwiritsidwa ntchito kwake mumakampani opanga ma chingwe ndi chiyembekezo cha chitukuko.
2. Kapangidwe ka nyumba
Pakupanga kapangidwe kake, kusintha chiŵerengero cha digiri ya polymerisation n/m kungapangitse kuchuluka kwa VA kuchokera pa 5 mpaka 90% ya EVA; kuwonjezera digiri yonse ya polymerisation kungapangitse kulemera kwa mamolekyulu kuchokera pa zikwi makumi ambiri kufika pa zikwi mazana ambiri za EVA; kuchuluka kwa VA pansi pa 40%, chifukwa cha kukhalapo kwa crystallisation pang'ono, kusalimba bwino, komwe kumadziwika kuti pulasitiki ya EVA; pamene kuchuluka kwa VA kuli koposa 40%, elastomer yofanana ndi rabara yopanda crystallisation, imadziwikanso kuti rabara ya EVM.
1. 2 Katundu
Unyolo wa mamolekyu wa EVA ndi wodzaza ndi mzere, kotero uli ndi kukalamba bwino kwa kutentha, nyengo yabwino komanso kukana ozoni.
Unyolo waukulu wa molekyulu ya EVA ulibe ma bond awiri, mphete ya benzene, acyl, magulu a amine ndi magulu ena osavuta kusuta akamayaka, unyolo wam'mbali ulibenso methyl, phenyl, cyano ndi magulu ena osavuta kusuta akamayaka. Kuphatikiza apo, molekyulu yokha ilibe zinthu za halogen, kotero ndiyoyenera makamaka mafuta oletsa utsi ochepa a halogen.
Kukula kwakukulu kwa gulu la vinyl acetate (VA) mu unyolo wa mbali wa EVA ndi polarity yake yapakati kumatanthauza kuti zonsezi zimaletsa chizolowezi cha msana wa vinyl kuti uume bwino ndikugwirizana bwino ndi ma mineral fillers, zomwe zimapangitsa kuti pakhale mafuta oletsa kugwira ntchito bwino. Izi ndi zoona makamaka pa utsi wochepa komanso wosakhala ndi halogen, chifukwa ma retardants okhala ndi voliyumu yoposa 50% [monga Al(OH) 3, Mg(OH) 2, etc.] ayenera kuwonjezedwa kuti akwaniritse zofunikira za miyezo ya chingwe kuti achepetse moto. EVA yokhala ndi VA yocheperako mpaka yapamwamba imagwiritsidwa ntchito ngati maziko opangira mafuta ochepetsa utsi komanso opanda halogen omwe ali ndi makhalidwe abwino kwambiri.
Popeza gulu la EVA side chain vinyl acetate (VA) ndi lozungulira, kuchuluka kwa VA kumakhala kwakukulu, polima imakhala yozungulira kwambiri ndipo kukana mafuta kumakhala bwino. Kukana mafuta komwe makampani opanga ma chingwe amafunikira makamaka kumatanthauza kuthekera kopirira mafuta amchere omwe si a polar kapena ofooka. Malinga ndi mfundo yogwirizana, EVA yokhala ndi kuchuluka kwa VA imagwiritsidwa ntchito ngati maziko opangira chotchinga chamafuta chochepa komanso chopanda halogen chokhala ndi kukana mafuta bwino.
Mamolekyulu a EVA mu alpha-olefin H atomu imagwira ntchito kwambiri, mu peroxide radicals kapena mphamvu zamagetsi zamagetsi zimakhala zosavuta kutenga H cross-linking reaction, kukhala cross-linking pulasitiki kapena mphira, zingatheke kukhala zofunikira pakuchita bwino kwa waya wapadera ndi zipangizo za chingwe.
Kuwonjezeredwa kwa gulu la vinyl acetate kumapangitsa kutentha kwa kusungunuka kwa EVA kutsika kwambiri, ndipo kuchuluka kwa ma VA short side chains kungapangitse kuti kuyenda kwa EVA kuchuluke. Chifukwa chake, magwiridwe antchito ake otulutsa mpweya ndi abwino kwambiri kuposa kapangidwe ka molekyulu ya polyethylene yofanana, kukhala chinthu chofunikira kwambiri pazida zotetezera mpweya ndi zotchingira mafuta zopanda halogen ndi halogen.
2 Ubwino wa malonda
2. 1 Kugwira ntchito mokwera mtengo kwambiri
Kapangidwe ka EVA ndi ka makina, kukana kutentha, kukana nyengo, kukana ozoni, ndi kagwiritsidwe ka magetsi ndi kabwino kwambiri. Sankhani kalasi yoyenera, kukana kutentha, kukana moto, komanso mafuta, chingwe chapadera cholimba.
Zipangizo za EVA zopangidwa ndi thermoplastic zimagwiritsidwa ntchito kwambiri ndi VA ya 15% mpaka 46%, yokhala ndi chiŵerengero chosungunuka cha magiredi 0.5 mpaka 4. EVA ili ndi opanga ambiri, mitundu yambiri, zosankha zosiyanasiyana, mitengo yotsika, kupezeka kokwanira, ogwiritsa ntchito amangofunika kutsegula gawo la EVA patsamba lawebusayiti, mtundu, magwiridwe antchito, mtengo, malo otumizira mwachangu, mungasankhe, ndikosavuta kwambiri.
EVA ndi polyolefin polymer, chifukwa cha kufewa ndi kugwiritsa ntchito kufananiza magwiridwe antchito, ndipo polyethylene (PE) ndi chingwe chofewa cha polyvinyl chloride (PVC) ndizofanana. Koma kafukufuku wowonjezereka, mupeza EVA ndi mitundu iwiri ya zinthu zomwe zili pamwambapa poyerekeza ndi kupambana kosasinthika.
2. 2 magwiridwe antchito abwino kwambiri
Kugwiritsa ntchito kwa EVA mu chingwe kumachokera ku zinthu zotchingira chingwe zapakati ndi zapamwamba mkati ndi kunja koyambira, kenako kumakulitsidwa mpaka ku chotchingira mafuta chopanda halogen. Mitundu iwiriyi ya zinthu kuchokera pamalingaliro ogwiritsira ntchito imawonedwa ngati "zinthu zodzazidwa kwambiri": zinthu zotchingira chifukwa chofuna kuwonjezera kuchuluka kwa kaboni wakuda woyendetsa ndikupangitsa kukhuthala kwake kukwera, kuchuluka kwa madzi kumatsika kwambiri; mafuta oletsa moto opanda halogen amafunika kuwonjezera kuchuluka kwa zinthu zoletsa moto zopanda halogen, komanso kukhuthala kwa zinthu zopanda halogen kumawonjezeka kwambiri, kuchuluka kwa madzi kumatsika kwambiri. Yankho ndikupeza polima yomwe ingakwaniritse kuchuluka kwa zodzaza, komanso yokhala ndi kukhuthala kochepa komanso kusinthasintha kwabwino. Pachifukwa ichi, EVA ndiye chisankho chomwe chimakondedwa.
Kukhuthala kwa kusungunuka kwa EVA ndi kutentha kwa extrusion processing ndi shear rate kudzawonjezera kuchepa kwachangu, wogwiritsa ntchito amangofunika kusintha kutentha kwa extruder ndi liwiro la screw, mutha kupanga magwiridwe antchito abwino kwambiri a waya ndi chingwe. Ntchito zambiri zapakhomo ndi zakunja zikuwonetsa kuti, pazinthu zopanda utsi wambiri zomwe zili ndi halogen, chifukwa kukhuthala kwake ndi kwakukulu kwambiri, melt index ndi yaying'ono kwambiri, kotero kugwiritsa ntchito low compression ratio screw (compression ratio ya zosakwana 1.3) extrusion, kuti zitsimikizire kuti extrusion ndi yabwino. Zipangizo za EVM zochokera ku rabara zokhala ndi vulcanising agents zitha kutulutsidwa pa extruders za rabara komanso zotulutsira zomwe zimagwiritsidwa ntchito kwambiri. Njira yotsatira ya vulcanisation (cross-linking) ikhoza kuchitika pogwiritsa ntchito thermochemical (peroxide) cross-linking kapena ndi electron accelerator irradiation cross-linking.
2. 3 Zosavuta kusintha ndikusintha
Mawaya ndi zingwe zili paliponse, kuyambira kumwamba mpaka pansi, kuyambira kumapiri mpaka kunyanja. Ogwiritsa ntchito zofunikira za waya ndi zingwe nawonso ndi osiyanasiyana komanso achilendo, pomwe kapangidwe ka waya ndi zingwe ndi kofanana, kusiyana kwa magwiridwe ake kumawonekera makamaka mu zinthu zotetezera kutentha ndi zophimba m'chimake.
Mpaka pano, kunyumba ndi kunja, PVC yofewa ikadali ndi gawo lalikulu la zipangizo za polima zomwe zimagwiritsidwa ntchito mumakampani opanga zingwe. Komabe, chifukwa cha chidziwitso chowonjezeka cha kuteteza chilengedwe ndi chitukuko chokhazikika.
Zipangizo za PVC zachepetsedwa kwambiri, asayansi akuchita zonse zomwe angathe kuti apeze zipangizo zina m'malo mwa PVC, zomwe zimalonjeza kwambiri ndi EVA.
EVA ikhoza kusakanizidwa ndi ma polima osiyanasiyana, komanso ndi ufa wosiyanasiyana wa mchere ndi zinthu zothandizira kukonza, zinthu zosakanikiranazo zitha kupangidwa kukhala pulasitiki ya thermoplastic ya zingwe za pulasitiki, komanso rabala yolumikizidwa ya zingwe za rabala. Opanga mapangidwe amatha kutengera zofunikira za ogwiritsa ntchito (kapena muyezo), EVA ngati chinthu choyambira, kuti ntchito ya chipangizocho ikwaniritse zofunikira.
3 EVA ntchito zosiyanasiyana
3. 1 Imagwiritsidwa ntchito ngati chotchingira cha semi-conductive cha zingwe zamagetsi amphamvu kwambiri
Monga tonse tikudziwa, zinthu zazikulu zomwe zimagwiritsidwa ntchito poteteza ndi zakuda zoyendetsa mpweya, zomwe zimapangidwa mu pulasitiki kapena rabara kuti ziwonjezere kuchuluka kwa kaboni wakuda zidzawononga kwambiri kusinthasintha kwa zinthu zotetezera komanso kusalala kwa kuchuluka kwa mpweya wotuluka. Pofuna kupewa kutuluka pang'ono kwa zingwe zamagetsi ambiri, zishango zamkati ndi zakunja ziyenera kukhala zoonda, zonyezimira, zowala komanso zofanana. Poyerekeza ndi ma polima ena, EVA imatha kuchita izi mosavuta. Chifukwa cha izi ndikuti njira yotulutsira mpweya ya EVA ndi yabwino kwambiri, imayenda bwino, ndipo siimatha kusungunuka mosavuta. Zinthu zotetezera zimagawidwa m'magulu awiri: zokutidwa ndi kondakitala kunja yotchedwa chishango chamkati - ndi zinthu zotchingira mkati; zokutidwa ndi insulation kunja yotchedwa chishango chakunja - ndi zinthu zotchingira kunja; zinthu zotchingira mkati makamaka zimakhala zotchingira mkati. Zinthu zotchingira mkati nthawi zambiri zimakhala zotchingira mkati ndipo nthawi zambiri zimachokera ku EVA yokhala ndi VA ya 18% mpaka 28%; zinthu zotchingira kunja nthawi zambiri zimakhala zolumikizidwa ndipo zimatha kusefedwa ndipo nthawi zambiri zimachokera ku EVA yokhala ndi VA ya 40% mpaka 46%.
3. 2 Mafuta oletsa moto opangidwa ndi thermoplastic ndi ogwirizana
Polyolefin yoletsa moto ya thermoplastic imagwiritsidwa ntchito kwambiri mumakampani opanga zingwe, makamaka pakufunika kwa zingwe zam'madzi, zingwe zamagetsi ndi mizere yomangira yapamwamba kwambiri ya halogen kapena halogen. Kutentha kwawo kwa nthawi yayitali kumakhala pakati pa 70 mpaka 90 °C.
Pa zingwe zamagetsi zapakati ndi zapamwamba za 10 kV ndi kupitirira apo, zomwe zimafunikira mphamvu zamagetsi zambiri, mphamvu zoletsa moto zimayendetsedwa makamaka ndi chidebe chakunja. M'nyumba zina kapena mapulojekiti omwe amawononga chilengedwe, zingwezo zimafunika kukhala ndi utsi wochepa, zopanda halogen, poizoni wochepa kapena utsi wochepa komanso mphamvu zoletsa halogen, kotero ma polyolefin oletsa moto a thermoplastic ndi yankho labwino.
Pazifukwa zina zapadera, m'mimba mwake wakunja si waukulu, kukana kutentha pakati pa chingwe chapadera ndi 105 ~ 150 ℃, zinthu zambiri zolumikizidwa ndi polyolefin, kulumikiza kwake kungasankhidwe ndi wopanga chingwe malinga ndi momwe amapangira, monga nthunzi yachikhalidwe kapena kusamba kwa mchere wotentha kwambiri, komanso njira yolumikizira kutentha kwa chipinda cha elekitironi yomwe imapezeka ndi njira yolumikizira kutentha kwa chipinda. Kutentha kwake kwa nthawi yayitali kumagawidwa m'mafayilo atatu a 105 ℃, 125 ℃, 150 ℃, ndipo chomera chopanga chingapangidwe malinga ndi zofunikira zosiyanasiyana za ogwiritsa ntchito kapena miyezo, chotchinga cha mafuta chopanda halogen kapena chopanda halogen.
Ndizodziwika bwino kuti ma polyolefin ndi ma polima osakhala a polar kapena ofooka. Popeza amafanana ndi mafuta amchere mu polarity, ma polyolefin nthawi zambiri amaonedwa kuti sangagonjetsedwe ndi mafuta motsatira mfundo yogwirizana mofanana. Komabe, miyezo yambiri ya chingwe kunyumba ndi kunja imatinso kuti kukana kolumikizidwa kuyeneranso kukhala ndi kukana bwino kwa mafuta, zosungunulira komanso ngakhale mafuta osungunuka, ma acid ndi alkali. Izi ndi zovuta kwa ofufuza zinthu, tsopano, kaya ku China kapena kunja, zinthuzi zovuta zapangidwa, ndipo maziko ake ndi EVA.
3. 3 Zinthu zotchinga mpweya
Zingwe zolumikizidwa ndi ma core ambiri zimakhala ndi malo ambiri pakati pa ma core omwe amafunika kudzazidwa kuti zitsimikizire kuti chingwe chozungulira chikuwoneka chozungulira, ngati chodzaza mkati mwa chidebe chakunja chapangidwa ndi chotchinga chamafuta chopanda halogen. Chotchinga ichi chimagwira ntchito ngati chotchinga chamoto (oxygen) chingwe chikayaka ndipo motero chimadziwika kuti "chotchinga cha mpweya" mumakampani.
Zofunikira zazikulu pa chipangizo chotchinga mpweya ndi izi: mphamvu zabwino zotulutsira mpweya, kuchedwa kwa moto kosagwiritsa ntchito halogen (mlozera wa mpweya nthawi zambiri umaposa 40) komanso mtengo wotsika.
Chotchinga cha okosijeni ichi chakhala chikugwiritsidwa ntchito kwambiri mumakampani opanga mawaya kwa zaka zoposa khumi ndipo chapangitsa kuti zingwe zisinthe kwambiri pakutha kwa moto. Chotchinga cha okosijeni chingagwiritsidwe ntchito pa zingwe zopanda halogen zomwe sizimayatsa moto komanso zingwe zopanda halogen zomwe sizimayatsa moto (monga PVC). Kafukufuku wambiri wasonyeza kuti zingwe zokhala ndi chotchinga cha okosijeni zimatha kupambana mayeso amodzi oyaka ndi oyaka.
Kuchokera pamalingaliro a kapangidwe ka zinthu, chotchinga cha mpweya ichi kwenikweni ndi "chodzaza kwambiri", chifukwa kuti mupeze mtengo wotsika, ndikofunikira kugwiritsa ntchito chodzaza chapamwamba, kuti mupeze index yayikulu ya mpweya, muyeneranso kuwonjezera gawo lalikulu (kawiri mpaka katatu) la Mg (OH) 2 kapena Al (OH) 3, ndikutulutsa zabwino ndi kusankha EVA ngati maziko.
3. 4 Zinthu zosinthira za PE
Zipangizo zophimba ma polyethylene zimakhala ndi mavuto awiri: choyamba, zimatha kusweka mosavuta (monga sharkskin) panthawi yotulutsa; chachiwiri, zimatha kusweka mosavuta chifukwa cha kupsinjika kwa chilengedwe. Yankho losavuta ndi kuwonjezera gawo lina la EVA mu kapangidwe kake. Imagwiritsidwa ntchito ngati EVA yosinthidwa makamaka pogwiritsa ntchito VA yochepa ya giredi, index yake yosungunuka pakati pa 1 mpaka 2 ndiyoyenera.
4. Ziyembekezo za chitukuko
(1) EVA yakhala ikugwiritsidwa ntchito kwambiri mumakampani opanga zingwe, kuchuluka kwa pachaka komwe kumakula pang'onopang'ono komanso mosalekeza. Makamaka m'zaka khumi zapitazi, chifukwa cha kufunika koteteza chilengedwe, kukana mafuta kochokera ku EVA kwakhala chitukuko chachangu, ndipo kwasintha pang'ono momwe zinthu za zingwe zochokera ku PVC zimakhalira. Kugwira ntchito kwake bwino kwambiri komanso magwiridwe antchito abwino kwambiri a njira yotulutsira zingwe ndizovuta kusintha zinthu zina zilizonse.
(2) chaka chilichonse makampani a chingwe amagwiritsa ntchito utomoni wa EVA pafupifupi matani 100,000, kusankha mitundu ya utomoni wa EVA, kuchuluka kwa VA kuyambira kotsika mpaka kokwera kudzagwiritsidwa ntchito, kuphatikiza ndi kukula kwa utomoni wa chingwe si kwakukulu, komwe kumafalikira m'mabizinesi onse chaka chilichonse m'matani masauzande ambiri a utomoni wa EVA mmwamba ndi pansi, motero sikudzakhala chidwi chachikulu cha makampani a EVA. Mwachitsanzo, kuchuluka kwakukulu kwa zinthu zoyambira zopanda moto zopanda halogen, kusankha kwakukulu kwa VA / MI = 28 /2 ~ 3 ya utomoni wa EVA (monga US DuPont's EVA 265 #). Ndipo kalasi iyi ya EVA mpaka pano palibe opanga opanga m'nyumba omwe angapange ndikupereka. Osatchula kuchuluka kwa VA kuposa 28, ndipo index yosungunuka yochepera 3 ya kupanga ndi kupereka zina za utomoni wa EVA.
(3) makampani akunja omwe amapanga EVA chifukwa chosakhala ndi mpikisano wapakhomo, ndipo mtengo wake wakhala wokwera kwa nthawi yayitali, zomwe zikuchepetsa chidwi cha mafakitale opanga zingwe zapakhomo. Makampani akunja opitilira 50% a VA omwe ali mu mtundu wa rabara wa EVM ndi omwe amalamulidwa ndi makampani akunja, ndipo mtengo wake ndi wofanana ndi wa VA womwe uli mu mtundu wa 2 mpaka 3. Mitengo yokwera yotereyi imakhudzanso kuchuluka kwa mtundu wa rabara wa EVM, kotero makampani opanga zingwe amafuna opanga ma EVA apakhomo kuti awonjezere kuchuluka kwa kupanga kwa EVA m'nyumba. Kupanga kwambiri kwa mafakitale kwakhala kugwiritsa ntchito kwambiri utomoni wa EVA.
(4) Podalira mafunde a chitetezo cha chilengedwe mu nthawi ya kudalirana kwa dziko lonse lapansi, makampani opanga zingwe amaona kuti EVA ndiye chinthu chabwino kwambiri choteteza mafuta osawononga chilengedwe. Kugwiritsa ntchito EVA kukukula ndi liwiro la 15% pachaka ndipo chiyembekezo chake n'chodalirika kwambiri. Kuchuluka ndi kuchuluka kwa zipangizo zotetezera komanso kupanga zingwe zamagetsi zamphamvu zapakati ndi zapamwamba komanso kuchuluka kwa kukula, pafupifupi 8% mpaka 10% pakati; kukana kwa polyolefin kukukula mofulumira, m'zaka zaposachedwapa kwakhalabe pa 15% mpaka 20% pakati, ndipo m'zaka 5 mpaka 10 zikubwerazi, kungasungenso kuchuluka kumeneku.
Nthawi yotumizira: Julayi-31-2022