Zomwe zimatchedwapolyurethanendiye chidule cha polyurethane, chomwe chimapangidwa ndi momwe ma polyisocyanates ndi polyols, ndipo chimakhala ndi magulu ambiri a amino ester (- NH-CO-O -) pa unyolo wa maselo. M'magulu enieni opangidwa ndi polyurethane, kuwonjezera pa gulu la amino ester, palinso magulu monga urea ndi biuret. Ma polyols ndi a mamolekyu aatali omwe ali ndi magulu a hydroxyl kumapeto, omwe amatchedwa "magawo a unyolo wofewa", pomwe ma polyisocyanates amatchedwa "magawo olimba a unyolo".
Pakati pa utomoni wa polyurethane wopangidwa ndi zigawo zofewa ndi zolimba, zochepa chabe ndi amino acid esters, kotero sizingakhale zoyenera kuzitcha polyurethane. M'lingaliro lalikulu, polyurethane ndi chowonjezera cha isocyanate.
Mitundu yosiyanasiyana ya isocyanates imachita ndi mankhwala a polyhydroxy kuti apange mapangidwe osiyanasiyana a polyurethane, potero amapeza zinthu za polima zomwe zimakhala ndi zinthu zosiyanasiyana, monga mapulasitiki, mphira, zokutira, ulusi, zomatira, etc.
Rabara ya polyurethane ndi ya mtundu wapadera wa mphira, womwe umapangidwa ndi polyether kapena polyester ndi isocyanate. Pali mitundu yambiri chifukwa cha mitundu yosiyanasiyana ya zopangira, momwe zimachitikira, komanso njira zolumikizirana. Kuchokera pamawonekedwe a mankhwala, pali mitundu ya polyester ndi polyether, ndipo kuchokera ku njira yopangira, pali mitundu itatu: mtundu wosakaniza, mtundu wa kuponyera, ndi mtundu wa thermoplastic.
Rabara ya Synthetic polyurethane nthawi zambiri imapangidwa pochita poliyesitala kapena poliyetha yokhala ndi diisocyanate kuti ipange prepolymer yotsika kwambiri ya molekyulu, yomwe pambuyo pake imayendetsedwa ndi chain extension reaction kuti ipange polima wolemera kwambiri. Kenako, zolumikizira zoyenera zimawonjezeredwa ndikutenthedwa kuti zichiritsidwe, kukhala mphira wovunda. Njirayi imatchedwa prepolymerization kapena njira ziwiri.
Ndikothekanso kugwiritsa ntchito njira imodzi - kusakaniza mwachindunji poliyesitala kapena polyether yokhala ndi diisocyanates, ma chain extenders, ndi othandizira ophatikizira kuti ayambe kuchitapo kanthu ndikupanga rabala ya polyurethane.
Gawo la A mu mamolekyu a TPU limapangitsa maunyolo a macromolecular kukhala osavuta kusinthasintha, kupatsa mphira wa polyurethane ndi kusalala bwino, kuchepetsa malo ochepetsera komanso kusintha kwachiwiri kwa polima, ndikuchepetsa kuuma kwake ndi mphamvu zamakina. Gawo la B lidzamanga kuzungulira kwa maunyolo a macromolecular, kuchititsa kuti malo ochepetsetsa ndi kusintha kwachiwiri kwa polima achuluke, zomwe zimapangitsa kuwonjezeka kwa kuuma ndi mphamvu zamakina, ndi kuchepa kwa elasticity. Mwa kusintha chiŵerengero cha molar pakati pa A ndi B, ma TPU okhala ndi makina osiyanasiyana amatha kupangidwa. Mapangidwe olumikizirana a TPU sayenera kungoganizira zolumikizira zoyambira, komanso kulumikizana kwachiwiri komwe kumapangidwa ndi ma hydrogen zomangira pakati pa mamolekyu. Chomangira chachikulu cholumikizira cha polyurethane ndi chosiyana ndi mawonekedwe a vulcanization a rabara ya hydroxyl. Gulu lake la amino ester, gulu la biuret, gulu la urea formate ndi magulu ena ogwira ntchito amakonzedwa m'gawo lokhazikika komanso lokhazikika, zomwe zimapangitsa kuti pakhale mawonekedwe amtundu wa rabara, omwe amakhala ndi kukana kovala bwino komanso zinthu zina zabwino kwambiri. Kachiwiri, chifukwa cha kukhalapo kwa magulu ambiri ogwirizana kwambiri, monga magulu a urea kapena carbamate mu rabara ya polyurethane, zomangira za haidrojeni zomwe zimapangidwa pakati pa maunyolo a molekyulu zimakhala ndi mphamvu zambiri, ndipo zomangira zachiwiri zophatikizika zomwe zimapangidwa ndi ma hydrogen bond zimathandizanso kwambiri mphira wa polyurethane. Kulumikizana kwachiwiri kumathandizira mphira wa polyurethane kukhala ndi mawonekedwe a ma thermosetting elastomers mbali imodzi, ndipo mbali inayo, kulumikizana kumeneku sikumalumikizana kwenikweni, ndikupangitsa kuti ikhale yolumikizirana. Chikhalidwe cholumikizirana chimadalira kutentha. Pamene kutentha kumawonjezeka, kugwirizanitsa kumeneku kumachepa pang'onopang'ono ndikuzimiririka. Polima imakhala ndi madzi enaake ndipo imatha kupangidwa ndi thermoplastic processing. Kutentha kumachepa, kulumikizana kumeneku kumabwerera pang'onopang'ono ndikupangikanso. Kuphatikizika kwa kachulukidwe kakang'ono kumawonjezera mtunda pakati pa mamolekyu, kufooketsa kuthekera kopanga zomangira za haidrojeni pakati pa mamolekyu, ndipo kumabweretsa kuchepa kwakukulu kwamphamvu. Kafukufuku wasonyeza kuti dongosolo la bata lamagulu osiyanasiyana ogwira ntchito mu rabara ya polyurethane kuchokera pamwamba mpaka pansi ndi: ester, ether, urea, carbamate, ndi biuret. Panthawi yokalamba ya rabara ya polyurethane, sitepe yoyamba ndiyo kuthyola zomangira zolumikizirana pakati pa biuret ndi urea, ndikutsatiridwa ndi kusweka kwa carbamate ndi urea, ndiko kuti, kusweka kwa unyolo waukulu.
01 Kufewetsa
Ma polyurethane elastomers, monga zida zambiri za polima, amafewetsa pa kutentha kwambiri ndikusintha kuchoka ku zotanuka kupita kumalo oyenda bwino, zomwe zimapangitsa kuchepa kwamphamvu kwamakina. Kuchokera pamalingaliro amankhwala, kufewetsa kwa kutentha kwa elasticity makamaka kumadalira zinthu monga momwe zimapangidwira, kulemera kwake kwa mamolekyulu, ndi kachulukidwe kolumikizana.
Nthawi zambiri, kuonjezera kulemera kwa mamolekyu, kuonjezera kulimba kwa gawo lolimba (monga kuyambitsa mphete ya benzene mu molekyulu) ndi zomwe zili mu gawo lolimba, ndikuwonjezera kachulukidwe kameneka ndizopindulitsa pakuwonjezera kutentha kwapang'onopang'ono. Kwa ma thermoplastic elastomers, kapangidwe ka maselo kamakhala mzere, ndipo kutentha kofewetsa kwa elastomer kumawonjezekanso pamene kulemera kwa ma molekyulu kumawonjezeka.
Kwa ma elastomer olumikizana ndi ma polyurethane, kachulukidwe wolumikizana amakhala ndi mphamvu yayikulu kuposa kulemera kwa maselo. Choncho, pamene kupanga elastomers, kuonjezera magwiridwe antchito a isocyanates kapena polyols akhoza kupanga thermally khola maukonde mankhwala mtanda kugwirizana dongosolo ena zotanuka mamolekyu, kapena kugwiritsa ntchito mopitirira muyeso isocyanate ratios kupanga khola isocyanate mtanda yolumikizira dongosolo mu zotanuka thupi ndi. njira yamphamvu yosinthira kukana kutentha, kukana zosungunulira, ndi mphamvu zamakina za elastomer.
PPDI (p-phenyldiisocyanate) ikagwiritsidwa ntchito ngati zopangira, chifukwa cha kulumikizana mwachindunji kwa magulu awiri a isocyanate ku mphete ya benzene, gawo lolimba lomwe limapangidwa limakhala ndi mphete yapamwamba ya benzene, yomwe imapangitsa kuti gawo lolimba likhale lolimba ndipo motero limawonjezera. kukana kutentha kwa elastomer.
Kuchokera pakuwona kwakuthupi, kutentha kofewa kwa ma elastomers kumadalira kuchuluka kwa kupatukana kwa microphase. Malinga ndi malipoti, kutentha kofewa kwa ma elastomers omwe samapatukana ndi ma microphase ndi otsika kwambiri, ndi kutentha kwa kutentha kwa pafupifupi 70 ℃, pomwe ma elastomers omwe amapatukana ndi microphase amatha kufika 130-150 ℃. Chifukwa chake, kukulitsa kuchuluka kwa kupatukana kwa microphase mu elastomers ndi imodzi mwa njira zolimbikitsira kukana kutentha kwawo.
Mlingo wa kulekana kwa microphase wa elastomers ukhoza kusinthidwa posintha kuchuluka kwa kulemera kwa maselo am'magawo a unyolo ndi zomwe zili m'magawo olimba a unyolo, potero kumawonjezera kukana kwawo kutentha. Ofufuza ambiri amakhulupirira kuti chifukwa microphase kulekana mu polyurethane ndi kusagwirizana thermodynamic pakati pa zigawo zofewa ndi zovuta. Mtundu wa chain extender, gawo lolimba ndi zomwe zili mkati mwake, mtundu wofewa wagawo, ndi kulumikizana kwa haidrojeni zonse zimakhudza kwambiri.
Poyerekeza ndi ma diol chain extenders, ma diamine chain extenders monga MOCA (3,3-dichloro-4,4-diaminodiphenylmethane) ndi DCB (3,3-dichloro-biphenylenediamine) amapanga magulu ambiri a polar amino ester mu elastomers, ndi ma hydrogen bond ambiri amatha. kupangidwa pakati pa zigawo zolimba, kuonjezera kuyanjana pakati pa zigawo zolimba ndikuwongolera kuchuluka kwa kupatukana kwa microphase mu elastomers; Symmetric onunkhira chain extenders monga p, p-dihydroquinone, ndi hydroquinone ndi opindulitsa pa normalization ndi kulongedza zolimba za zigawo zolimba, potero kusintha microphase kulekana kwa zinthu.
Magawo a amino ester opangidwa ndi aliphatic isocyanates amalumikizana bwino ndi zigawo zofewa, zomwe zimapangitsa kuti zigawo zolimba kwambiri zisungunuke m'magawo ofewa, kuchepetsa kuchuluka kwa kulekanitsidwa kwa microphase. Magawo a amino ester opangidwa ndi ma isocyanates onunkhira samalumikizana bwino ndi magawo ofewa, pomwe kuchuluka kwa kupatukana kwa microphase ndikwambiri. Polyolefin polyurethane ali ndi pafupifupi wathunthu microphase kupatukana dongosolo chifukwa chakuti gawo zofewa sapanga ma hydrogen zomangira ndi hydrogen zomangira akhoza kuchitika mu gawo lolimba.
Zotsatira za kugwirizana kwa haidrojeni pamalo ochepetsetsa a elastomers ndizofunikanso. Ngakhale ma polyethers ndi ma carbonyls mu gawo lofewa amatha kupanga zomangira zambiri za haidrojeni ndi NH mugawo lolimba, zimawonjezeranso kutentha kofewa kwa ma elastomers. Zatsimikiziridwa kuti ma hydrogen bond amasungabe 40% pa 200 ℃.
02 Kuwonongeka kwa kutentha
Magulu a amino ester amawola motere pa kutentha kwakukulu:
- RNHCOOR - RNC0 HO-R
- RNHCOOR - RNH2 CO2 ene
- RNHCOOR - RNHR CO2 ene
Pali mitundu itatu yayikulu yakuwonongeka kwamafuta azinthu zopangidwa ndi polyurethane:
① Kupanga ma isocyanates oyambilira ndi ma polyols;
② α— Chomangira cha okosijeni pa maziko a CH2 chimasweka ndikuphatikiza ndi chomangira cha haidrojeni pa chachiwiri cha CH2 kupanga ma amino acid ndi ma alkenes. Ma amino acid amawola kukhala amine imodzi yayikulu ndi carbon dioxide:
③ Fomu 1 yachiwiri ya amine ndi carbon dioxide.
Kuwola kwamafuta amtundu wa carbamate:
Aryl NHCO Aryl, ~ 120 ℃;
N-alkyl-NHCO-aryl, ~ 180 ℃;
Aryl NHCO n-alkyl, ~ 200 ℃;
N-alkyl-NHCO-n-alkyl, ~ 250 ℃.
Kukhazikika kwamafuta a amino acid esters kumagwirizana ndi mitundu ya zinthu zoyambira monga isocyanates ndi polyols. Aliphatic isocyanates ndi okwera kuposa ma isocyanates onunkhira, pomwe mafuta amchere amakhala okwera kuposa ma alcohols onunkhira. Komabe, zolembazo zimati kutentha kwa kutentha kwa aliphatic amino acid esters kuli pakati pa 160-180 ℃, ndipo kununkhira kwa amino acid esters kuli pakati pa 180-200 ℃, zomwe sizikugwirizana ndi zomwe zili pamwambapa. Chifukwa chingakhale chokhudzana ndi njira yoyesera.
M'malo mwake, aliphatic CHDI (1,4-cyclohexane diisocyanate) ndi HDI (hexamethylene diisocyanate) ali ndi kukana kutentha kwambiri kuposa zomwe zimagwiritsidwa ntchito nthawi zambiri zonunkhira za MDI ndi TDI. Makamaka trans CHDI yokhala ndi ma symmetrical system yadziwika kuti isocyanate yosamva kutentha kwambiri. Ma polyurethane elastomers okonzedwa kuchokera pamenepo ali ndi processability wabwino, kukana kwa hydrolysis, kutentha kwakukulu, kutentha kwa galasi lotsika, kutsika kwamafuta, komanso kukana kwa UV.
Kuphatikiza pa gulu la amino ester, polyurethane elastomers ilinso ndi magulu ena ogwira ntchito monga urea formate, biuret, urea, etc. Maguluwa amatha kuwonongeka chifukwa cha kutentha kwambiri:
NHCONCOO - (aliphatic urea formate), 85-105 ℃;
- NHCONCOO - (onunkhira urea formate), pa kutentha osiyanasiyana 1-120 ℃;
- NHCONCONH - (aliphatic biuret), pa kutentha kuyambira 10 ° C mpaka 110 ° C;
NHCONCONH - (onunkhira biuret), 115-125 ℃;
NHCONH - (aliphatic urea), 140-180 ℃;
- NHCONH - (onunkhira urea), 160-200 ℃;
mphete ya isocyanurate>270 ℃.
Kutentha kwa kutentha kwa biuret ndi urea based formate ndikotsika kwambiri kuposa kwa aminoformate ndi urea, pomwe isocyanurate ili ndi kukhazikika kwamafuta. Popanga ma elastomers, ma isocyanate ochulukirapo amathanso kuchitapo kanthu popanga ma aminoformate ndi urea kupanga urea based formate ndi biuret yolumikizana. Ngakhale amatha kusintha makina a elastomers, amakhala osakhazikika pakuwotcha.
Kuti muchepetse magulu osakhazikika amafuta monga biuret ndi urea formate mu elastomers, ndikofunikira kuganizira kuchuluka kwawo kwazinthu zopangira komanso kupanga. Kuchulukitsa kwa isocyanate kuyenera kugwiritsidwa ntchito, ndipo njira zina ziyenera kugwiritsidwa ntchito momwe zingathere kuti apange mphete za isocyanate muzopangira (makamaka isocyanates, polyols, ndi ma chain extenders), ndiyeno kuzilowetsa mu elastomer molingana ndi njira zanthawi zonse. Iyi yakhala njira yomwe imagwiritsidwa ntchito kwambiri popangira ma elastomers osatentha komanso osamva malawi a polyurethane.
03 Hydrolysis ndi matenthedwe oxidation
Ma polyurethane elastomers amatha kuwonongeka kwamafuta m'zigawo zawo zolimba komanso kusintha kwamankhwala komwe kumayendera m'zigawo zawo zofewa pakutentha kwambiri. Ma polyester elastomers ali ndi vuto losamva madzi komanso chizolowezi chowopsa cha hydrolyze pa kutentha kwambiri. Moyo wothandizira wa polyester / TDI / diamine ukhoza kufika miyezi 4-5 pa 50 ℃, masabata awiri okha pa 70 ℃, ndi masiku ochepa okha pamwamba pa 100 ℃. Zomangira za Ester zimatha kuwola kukhala ma acid ndi mowa wofananira akakumana ndi madzi otentha ndi nthunzi, ndipo magulu a urea ndi amino ester mu elastomers amathanso kukhudzidwa ndi hydrolysis:
RCOOR H20- → RCOOH HOR
Ester mowa
RNHCONHR imodzi H20- → RXHCOOH H2NR -
Ureamide
Mmodzi RNHCOOR-H20- → RNCOOH HOR -
Amino formate ester Amino formate mowa
Ma elastomer opangidwa ndi polyether amakhala ndi kukhazikika kwa matenthedwe amafuta, ndipo ma elastomers opangidwa ndi etha α- The haidrojeni pa atomu ya kaboni ndi oxidized mosavuta, kupanga hydrogen peroxide. Pambuyo pakuwola ndi kung'ambika kwina, imapanga ma oxide radicals ndi ma hydroxyl radicals, omwe pamapeto pake amawola kukhala mawonekedwe kapena aldehydes.
Ma polyesters osiyanasiyana alibe mphamvu zochepa pakukana kutentha kwa ma elastomers, pomwe ma polyesters osiyanasiyana ali ndi chikoka china. Poyerekeza ndi TDI-MOCA-PTMEG, TDI-MOCA-PTMEG ili ndi mphamvu yosunga mphamvu ya 44% ndi 60% motsatana ikafika zaka 121 ℃ kwa masiku 7, yomalizayo imakhala yabwinoko kuposa yakale. Chifukwa chake chikhoza kukhala kuti mamolekyu a PPG ali ndi maunyolo a nthambi, omwe sakugwirizana ndi dongosolo lokhazikika la mamolekyu otanuka komanso kuchepetsa kutentha kwa thupi. Matenthedwe okhazikika a ma polyeters ndi: PTMEG> PEG> PPG.
Magulu ena ogwira ntchito mu polyurethane elastomers, monga urea ndi carbamate, amakumananso ndi ma oxidation ndi hydrolysis reaction. Komabe, gulu la ether ndilosavuta kukhala ndi okosijeni, pamene gulu la ester ndilosavuta kwambiri la hydrolyzed. Dongosolo la kukana kwawo kwa antioxidant ndi hydrolysis ndi:
Antioxidant ntchito: esters> urea> carbamate> ether;
Hydrolysis resistance: ester
Kupititsa patsogolo kukana kwa okosijeni wa polyether polyurethane ndi kukana kwa hydrolysis kwa polyester polyurethane, zowonjezera zimawonjezeredwa, monga kuwonjezera 1% phenolic antioxidant Irganox1010 ku PTMEG polyether elastomer. Kulimba kwamphamvu kwa elastomer iyi kumatha kuonjezeredwa ndi nthawi 3-5 poyerekeza ndi opanda antioxidants (zotsatira zoyesa mutakalamba pa 1500C kwa maola 168). Koma si antioxidant iliyonse imakhala ndi mphamvu pa polyurethane elastomers, phenolic 1rganox 1010 yokha ndi TopanOl051 (phenolic antioxidant, inalepheretsa amine light stabilizer, benzotriazole complex) imakhala ndi zotsatira zazikulu, ndipo yoyamba ndiyo yabwino kwambiri, mwina chifukwa phenolic antioxidants imagwirizana bwino ndi elastomers. Komabe, chifukwa cha gawo lofunikira la magulu a phenolic hydroxyl mu njira yokhazikika ya phenolic antioxidants, pofuna kupewa zomwe zimachitika komanso "kulephera" kwa gulu la phenolic hydroxyl ndi magulu a isocyanate mu dongosolo, chiŵerengero cha isocyanates ndi polyols sichiyenera kukhala. zazikulu kwambiri, ndipo ma antioxidants ayenera kuwonjezeredwa ku ma prepolymers ndi ma chain extenders. Ngati awonjezeredwa pakupanga ma prepolymers, zidzakhudza kwambiri kukhazikika kwamphamvu.
Zowonjezera zomwe zimagwiritsidwa ntchito poletsa hydrolysis ya polyester polyurethane elastomers makamaka ndi mankhwala a carbodiimide, omwe amakhudzidwa ndi ma carboxylic acid opangidwa ndi ester hydrolysis mu mamolekyu a polyurethane elastomer kuti apange zotumphukira za acyl urea, kuteteza hydrolysis yowonjezereka. Kuphatikiza kwa carbodiimide pagawo lalikulu la 2% mpaka 5% kumatha kuwonjezera kukhazikika kwamadzi a polyurethane ndi 2-4 nthawi. Kuphatikiza apo, tert butyl catechol, hexamethylenetetramine, azodicarbonamide, ndi zina zambiri zimakhalanso ndi zotsutsana ndi hydrolysis.
04 Makhalidwe abwino kwambiri
Ma polyurethane elastomers ndi ofanana ndi ma copolymer angapo, okhala ndi unyolo wa ma molekyulu wopangidwa ndi magawo osinthika okhala ndi kutentha kwa galasi lotsika kuposa kutentha kwachipinda komanso magawo olimba okhala ndi kutentha kwa galasi kuposa kutentha kwachipinda. Mwa iwo, ma polyols a oligomeric amapanga magawo osinthika, pomwe ma diisocyanate ndi ma molekyulu ang'onoang'ono owonjezera amapanga magawo olimba. Mapangidwe ophatikizidwa a magawo osinthika komanso okhwima amatengera momwe amagwirira ntchito:
(1) Kuuma kwa mphira wamba nthawi zambiri kumakhala pakati pa Shaoer A20-A90, pomwe kuuma kwa pulasitiki ndi Shaoer A95 Shaoer D100. Ma polyurethane elastomers amatha kufikira otsika ngati Shaoer A10 komanso okwera ngati Shaoer D85, popanda kufunikira kwa chithandizo chodzaza;
(2) Mphamvu zapamwamba ndi kusungunuka zimatha kusungidwa mkati mwa kuuma kosiyanasiyana;
(3) Kukana kuvala kwabwino, nthawi 2-10 kuposa mphira wachilengedwe;
(4) Kukaniza bwino madzi, mafuta, ndi mankhwala;
(5) Kukana kwamphamvu kwambiri, kukana kutopa, komanso kukana kugwedezeka, koyenera kugwiritsa ntchito ma frequency apamwamba;
(6) Good otsika kutentha kukana, ndi otsika kutentha brittleness pansipa -30 ℃ kapena -70 ℃;
(7) Ili ndi ntchito yabwino kwambiri yotchinjiriza, ndipo chifukwa cha kutsika kwake kwamafuta, imakhala ndi zotsatira zabwino zotchinjiriza poyerekeza ndi mphira ndi pulasitiki;
(8) Good biocompatibility ndi anticoagulant katundu;
(9) Kutchinjiriza kwamagetsi kwabwino, kukana nkhungu, komanso kukhazikika kwa UV.
Ma polyurethane elastomers amatha kupangidwa pogwiritsa ntchito njira zomwezo monga mphira wamba, monga pulasitiki, kusakaniza, ndi vulcanization. Atha kupangidwanso ngati mphira wamadzimadzi pothira, kuumba centrifugal, kapena kupopera mbewu mankhwalawa. Atha kupangidwanso kukhala zida za granular ndikupangidwa pogwiritsa ntchito jekeseni, extrusion, kugudubuza, kuumba nkhonya, ndi njira zina. Mwanjira imeneyi, sikuti zimangowonjezera magwiridwe antchito, komanso zimathandizira kuti chinthucho chikhale cholondola komanso mawonekedwe ake.
Nthawi yotumiza: Dec-05-2023