Abin da ake kirapolyurethaneshi ne taƙaitaccen bayanin polyurethane, wanda aka samo shi ta hanyar amsawar polyisocyanates da polyols, kuma ya ƙunshi ƙungiyoyin amino ester masu maimaitawa da yawa (- NH-CO-O -) akan sarkar kwayoyin. A haƙiƙanin haɗe-haɗe na resin polyurethane, ban da rukunin amino ester, akwai kuma ƙungiyoyi kamar urea da biuret. Polyols na cikin kwayoyin halitta mai tsayi tare da ƙungiyoyin hydroxyl a ƙarshe, waɗanda ake kira " sassan sarkar mai laushi ", yayin da ake kira polyisocyanates "tsararrun sarkar sarkar".
Daga cikin resins na polyurethane waɗanda sassa masu laushi da sarƙaƙƙiya ke samarwa, ƙananan kaso ne kawai esters amino acid, don haka bazai dace a kira su polyurethane ba. A cikin ma'ana mai faɗi, polyurethane ƙari ne na isocyanate.
Daban-daban na isocyanates suna amsawa tare da mahaɗan polyhydroxy don samar da sifofi daban-daban na polyurethane, don haka samun kayan polymer tare da kaddarorin daban-daban, kamar su robobi, roba, sutura, filaye, adhesives, da sauransu.
Rubber polyurethane na wani nau'in roba ne na musamman, wanda aka yi ta hanyar amsa polyether ko polyester tare da isocyanate. Akwai nau'ikan iri da yawa saboda nau'ikan albarkatun ƙasa daban-daban, yanayin amsawa, da hanyoyin haɗin kai. Daga mahangar tsarin sinadarai, akwai nau'ikan polyester da polyether, kuma ta fuskar hanyar sarrafawa, nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan nau'ikan iri ne: nau'in hadawa, nau'in simintin gyare-gyare, da nau'in thermoplastic.
Roba polyurethane roba gabaɗaya ana haɗa shi ta hanyar amsa polyester madaidaiciya ko polyether tare da diisocyanate don samar da prepolymer mara nauyi na ƙwayoyin cuta, wanda sannan aka sanya shi da amsa sarƙoƙi don samar da babban nau'in polymer. Sa'an nan kuma, ana ƙara ma'auni masu dacewa masu dacewa da kuma zafi don magance shi, ya zama roba mai lalacewa. Ana kiran wannan hanyar prepolymerization ko hanyar mataki biyu.
Hakanan yana yiwuwa a yi amfani da hanyar mataki ɗaya - kai tsaye haɗa polyester madaidaiciya ko polyether tare da diisocyanates, sarkar sarkar, da ma'aikatan haɗin gwiwa don fara amsawa da samar da roba polyurethane.
A-segment a cikin kwayoyin TPU suna sa sarƙoƙin macromolecular sauƙi don juyawa, yana ba da roba polyurethane tare da elasticity mai kyau, rage maƙasudin laushi da matsakaicin matsayi na biyu na polymer, da rage taurinsa da ƙarfin injin. Sashin B zai ɗaure jujjuyawar sarƙoƙi na macromolecular, yana haifar da laushi mai laushi da matsayi na biyu na polymer don haɓakawa, yana haifar da haɓaka taurin ƙarfi da ƙarfin injin, da raguwar elasticity. Ta hanyar daidaita rabon molar tsakanin A da B, ana iya samar da TPUs tare da kaddarorin inji daban-daban. Tsarin haɗin giciye na TPU dole ne ba kawai la'akari da haɗin giciye na farko ba, har ma da haɗin giciye na biyu da aka kafa ta hanyar haɗin gwiwar hydrogen tsakanin kwayoyin halitta. Babban haɗin haɗin haɗin gwiwa na farko na polyurethane ya bambanta da tsarin vulcanization na roba hydroxyl. Ƙungiyar amino ester, ƙungiyar biuret, ƙungiyar urea formate da sauran ƙungiyoyi masu aiki an shirya su a cikin wani tsari na yau da kullum da kuma sararin samaniya, wanda ya haifar da tsarin hanyar sadarwa na yau da kullum na roba, wanda ke da kyakkyawan juriya da sauran kyawawan kaddarorin. Abu na biyu, saboda kasancewar ƙungiyoyin ayyuka masu haɗa kai da yawa irin su urea ko ƙungiyoyin carbamate a cikin roba na polyurethane, haɗin gwiwar hydrogen da aka kafa tsakanin sarƙoƙi na ƙwayoyin cuta suna da ƙarfi sosai, kuma haɗin giciye na biyu da aka kirkira ta hanyar haɗin gwiwar hydrogen shima yana da tasiri mai mahimmanci akan kaddarorin roba polyurethane. Haɗin giciye na biyu yana ba da damar roba na polyurethane don mallakar halayen thermosetting elastomers a hannu ɗaya, kuma a gefe guda, wannan haɗin giciye ba shi da alaƙa da gaske, yana mai da shi haɗin giciye mai kama-da-wane. Yanayin haɗin kai ya dogara da zafin jiki. Yayin da zafin jiki ya ƙaru, wannan haɗin giciye a hankali yana raunana kuma yana ɓacewa. Polymer yana da ɗan ruwa kuma ana iya yin shi da sarrafa thermoplastic. Lokacin da zafin jiki ya ragu, wannan haɗin giciye a hankali yana farfadowa kuma ya sake farawa. Ƙara ƙaramin adadin filler yana ƙara tazara tsakanin kwayoyin halitta, yana raunana ikon samar da haɗin hydrogen tsakanin kwayoyin halitta, kuma yana haifar da raguwa mai ƙarfi. Bincike ya nuna cewa tsarin kwanciyar hankali na ƙungiyoyin aiki daban-daban a cikin roba polyurethane daga sama zuwa ƙasa shine: ester, ether, urea, carbamate, da biuret. A lokacin tsufa na roba na polyurethane, mataki na farko shine karya haɗin haɗin kai tsakanin biuret da urea, sannan kuma karyawar carbamate da urea, wato babban sarkar.
01 Tausasawa
Polyurethane elastomers, kamar yawancin kayan polymer, suna yin laushi a yanayin zafi mai yawa da kuma canzawa daga yanayin roba zuwa yanayin kwarara mai danko, yana haifar da raguwa cikin sauri a ƙarfin injin. Daga mahangar sinadarai, zafin jiki mai laushi na elasticity ya dogara ne akan abubuwa kamar su sinadaran abun da ke tattare da shi, nauyin kwayoyin halittar dangi, da ma'aunin giciye.
Gabaɗaya magana, haɓaka nauyin ƙwayar ƙwayar ƙwayar ƙwayar cuta, haɓaka ƙaƙƙarfan yanki mai wuya (kamar shigar da zoben benzene a cikin kwayar halitta) da abun ciki na ɓangaren wuya, da haɓaka haɓakar haɗin gwiwa duk suna da fa'ida don ƙara yawan zafin jiki mai laushi. Ga thermoplastic elastomers, tsarin kwayoyin halitta galibi layi ne, kuma yanayin zafi mai laushi na elastomer shima yana ƙaruwa lokacin da aka ƙara nauyin kwayoyin halitta.
Don masu haɗin gwiwar polyurethane elastomers, haɓakar haɗin gwiwa yana da tasiri mafi girma fiye da nauyin kwayoyin halitta. Saboda haka, a lokacin da masana'antu elastomers, ƙara da ayyuka na isocyanates ko polyols iya samar da thermally barga cibiyar sadarwa sinadaran giciye tsarin a cikin wasu daga cikin na roba kwayoyin, ko amfani da wuce kima isocyanate rabo don samar da wani barga isocyanate giciye-linking tsarin a cikin na roba jiki ne. hanya mai ƙarfi don haɓaka juriyar zafi, juriya mai ƙarfi, da ƙarfin injin na'urar elastomer.
Lokacin da aka yi amfani da PPDI (p-phenyldiisocyanate) azaman albarkatun ƙasa, saboda haɗin kai tsaye na ƙungiyoyin isocyanate guda biyu zuwa zoben benzene, ɓangaren da aka kafa mai wuya yana da babban abun ciki na zobe na benzene, wanda ke inganta tsattsauran ra'ayi na sashi mai wuya kuma don haka yana haɓakawa. da zafi juriya na elastomer.
Daga hangen nesa ta jiki, zafin jiki mai laushi na elastomers ya dogara da matakin rabuwar microphase. A cewar rahotanni, da taushi zafin jiki na elastomers da ba su sha microphase rabuwa ne sosai low, tare da aiki zafin jiki na kawai game da 70 ℃, yayin da elastomers da ke jurewa microphase rabuwa iya isa 130-150 ℃. Sabili da haka, haɓaka matakin rarrabuwar microphase a cikin elastomers yana ɗaya daga cikin ingantattun hanyoyin inganta juriyar zafi.
Digiri na Microphase rabuwa da ealastomers za a iya inganta ta hanyar canza rarraba sarkar sarkar da kuma abun da ke hana sarkar sarkar, ta haka inganta juriya da zafi. Yawancin masu bincike sunyi imanin cewa dalilin rabuwar microphase a cikin polyurethane shine rashin daidaituwa na thermodynamic tsakanin sassa masu laushi da wuya. Nau'in mai shimfiɗa sarkar, sashi mai wuya da abun ciki, nau'in sashi mai laushi, da haɗin gwiwar hydrogen duk suna da tasiri mai mahimmanci akan shi.
Idan aka kwatanta da sarkar diol, sarkar diamine irin su MOCA (3,3-dichloro-4,4-diaminodiphenylmethane) da DCB (3,3-dichloro-biphenylenediamine) sun samar da ƙarin rukunin amino ester na polar a cikin elastomers, kuma ƙarin haɗin gwiwar hydrogen zai iya. za a kafa tsakanin sassa masu wuyar gaske, haɓaka hulɗar tsakanin sassa masu wuya da kuma inganta matakin rabuwa na microphase a cikin elastomers; Matsakaicin sarkar kamshi mai kamshi irin su p, p-dihydroquinone, da hydroquinone suna da fa'ida don daidaitawa da matsattsewar sassa masu wuya, ta haka inganta rarrabuwar samfuran microphase.
Sassan amino ester da aka kafa ta aliphatic isocyanates suna da dacewa mai kyau tare da sassa masu laushi, wanda ya haifar da ƙarin sassauƙa mai wuyar warwarewa a cikin sassa masu laushi, rage matakin rabuwar microphase. Sassan amino ester da aka kirkira ta isocyanates na aromatic suna da rashin daidaituwa tare da sassa masu laushi, yayin da matakin rabuwar microphase ya fi girma. Polyolefin polyurethane yana da kusan cikakkiyar tsarin rabuwa na microphase saboda gaskiyar cewa sashin mai laushi ba ya samar da haɗin gwiwar hydrogen kuma haɗin hydrogen zai iya faruwa ne kawai a cikin yanki mai wuya.
Hakanan tasirin haɗin hydrogen akan wurin laushi na elastomers shima yana da mahimmanci. Ko da yake polyethers da carbonyls a cikin sassa mai laushi na iya samar da adadi mai yawa na haɗin hydrogen tare da NH a cikin yanki mai wuya, kuma yana ƙara yawan zafin jiki na elastomers. An tabbatar da cewa har yanzu abubuwan haɗin hydrogen suna riƙe 40% a 200 ℃.
02 Bazuwar thermal
Ƙungiyoyin Amino ester suna fuskantar bazuwar mai zuwa a yanayin zafi mai girma:
RNHCOOR - RNC0 HO-R
RNHCOOR - RNH2 CO2 ene
- RNHCOOR - RNHR CO2 ene
Akwai manyan nau'ikan bazuwar thermal guda uku na tushen kayan polyurethane:
① Samar da isocyanates na asali da polyols;
② α- Oxygen bond akan CH2 tushe ya karye kuma ya haɗu da haɗin hydrogen ɗaya akan CH2 na biyu don samar da amino acid da alkenes. Amino acids suna raguwa zuwa aminin farko da carbon dioxide:
③ Form 1 amine na biyu da carbon dioxide.
Thermal bazuwar tsarin carbamate:
Aryl NHCO Aryl, ~ 120 ℃;
N-alkyl-NHCO-aryl, ~ 180 ℃;
Aryl NHCO n-alkyl, ~ 200 ℃;
N-alkyl-NHCO-n-alkyl,~250 ℃.
Tsayayyen yanayin zafi na esters amino acid yana da alaƙa da nau'ikan kayan farawa kamar isocyanates da polyols. Aliphatic isocyanates sun fi isocyanates na aromatic girma, yayin da barasa masu kitse sun fi barasa masu ƙanshi. Duk da haka, wallafe-wallafen sun ba da rahoton cewa zafin bazuwar zafin jiki na aliphatic amino acid esters yana tsakanin 160-180 ℃, kuma na amino acid esters na aromatic yana tsakanin 180-200 ℃, wanda bai dace da bayanan da ke sama ba. Dalilin yana iya kasancewa yana da alaƙa da hanyar gwaji.
A gaskiya ma, CHDI aliphatic (1,4-cyclohexane diisocyanate) da HDI (hexamethylene diisocyanate) suna da mafi kyawun juriya na zafi fiye da amfani da MDI da TDI mai ƙanshi. Musamman trans CHDI tare da tsarin daidaitawa an gane shi azaman isocyanate mafi jure zafi. Polyurethane elastomers da aka shirya daga gare ta suna da kyakkyawan tsari, kyakkyawan juriya na hydrolysis, matsanancin zafin jiki mai laushi, ƙarancin canjin gilashin, ƙarancin zafin jiki na thermal, da babban juriya na UV.
Baya ga rukunin amino ester, polyurethane elastomers kuma suna da wasu ƙungiyoyi masu aiki kamar urea formate, biuret, urea, da sauransu. Waɗannan ƙungiyoyin na iya fuskantar bazuwar thermal a yanayin zafi:
NHCONCOO - (aliphatic urea formate), 85-105 ℃;
- NHCONCOO - (ƙarashin urea formate), a zazzabi kewayon 1-120 ℃;
- NHCONCONH - (aliphatic biuret), a zazzabi daga 10 ° C zuwa 110 ° C;
NHCONCONH - (biuret aromatic), 115-125 ℃;
NHCONH - (aliphatic urea), 140-180 ℃;
- NHCONH - (urea aromatic), 160-200 ℃;
Isocyanurate zobe> 270 ℃.
Thermal bazuwar zafin jiki na biuret da urea tushen formate ya fi na aminoformate da urea, yayin da isocyanurate yana da mafi kyawun kwanciyar hankali na thermal. A cikin samar da elastomers, wuce kima isocyyanates iya kara mayar da martani tare da kafa aminoformate da urea don samar da urea tushen formate da biuret giciye-linked Tsarin. Ko da yake suna iya inganta kayan aikin injiniyoyi na elastomers, suna da matuƙar rashin kwanciyar hankali don zafi.
Don rage thermal m kungiyoyin kamar biuret da urea formate a elastomers, shi wajibi ne don la'akari da albarkatun kasa rabo da kuma samar da tsari. Ya kamata a yi amfani da ma'aunin isocyanate mai yawa, kuma ya kamata a yi amfani da wasu hanyoyin gwargwadon yadda zai yiwu don fara samar da zoben isocyanate na farko a cikin albarkatun kasa (yafi isocyyanates, polyols, da sarkar sarkar), sa'an nan kuma gabatar da su a cikin elastomer bisa ga tsarin al'ada. Wannan ya zama hanyar da aka fi amfani da ita don samar da polyurethane elastomers masu jure zafi da harshen wuta.
03 Hydrolysis da thermal oxidation
Polyurethane elastomers suna da haɗari ga bazuwar thermal a cikin sassansu masu wuya da kuma daidaitattun canje-canjen sinadarai a cikin sassansu masu laushi a yanayin zafi mai girma. Polyester elastomers suna da ƙarancin juriya na ruwa da kuma yanayin da ya fi dacewa don yin ruwa a yanayin zafi. Rayuwar sabis na polyester/TDI/diamine na iya kaiwa watanni 4-5 a 50 ℃, makonni biyu kawai a 70 ℃, kuma 'yan kwanaki sama da 100 ℃. Ester bond na iya lalacewa zuwa daidaitattun acid da alcohols lokacin da aka fallasa su zuwa ruwan zafi da tururi, kuma urea da rukunin amino ester a cikin elastomer suma suna iya fuskantar halayen hydrolysis:
RCOOR H20- → RCOOH HOR
Ester barasa
RNHCONHR daya H20- → RXHCOOH H2NR -
Ureamide
Daya RNHCOOR-H20- → RNCOOH HOR -
Amino formate ester Amino formate barasa
Polyether na tushen elastomers suna da rashin kwanciyar hankali na thermal oxidation, da ether tushen elastomers α- hydrogen akan zarra na carbon yana da sauƙi oxidized, yana samar da hydrogen peroxide. Bayan kara lalacewa da tsagewa, yana haifar da radicals oxide da hydroxyl radicals, wanda a ƙarshe ya zama cikin tsari ko aldehydes.
Polyesters daban-daban suna da ɗan tasiri akan juriya na zafi na elastomers, yayin da polyester daban-daban suna da wani tasiri. Idan aka kwatanta da TDI-MOCA-PTMEG, TDI-MOCA-PTMEG yana da ƙarfin riƙe ƙarfi na 44% da 60% bi da bi lokacin da ya tsufa a 121 ℃ na kwanaki 7, tare da ƙarshen yana da mahimmanci fiye da na farko. Dalili na iya zama cewa kwayoyin PPG suna da sarƙoƙi masu rassa, waɗanda ba su dace da tsari na yau da kullum na ƙwayoyin roba ba kuma suna rage yawan zafin jiki na jiki na roba. Tsarin kwanciyar hankali na thermal na polyethers shine: PTMEG>PEG>PPG.
Sauran ƙungiyoyin aiki a cikin elastomer na polyurethane, irin su urea da carbamate, suma suna shan iskar oxygen da halayen hydrolysis. Duk da haka, ƙungiyar ether ita ce mafi sauƙi oxidized, yayin da ƙungiyar ester ita ce mafi sauƙin hydrolyzed. Tsarin maganin antioxidant da juriya na hydrolysis shine:
Ayyukan antioxidant: esters>urea>carbamate>ether;
Hydrolysis juriya: ester
Don inganta juriya na iskar shaka na polyether polyurethane da juriya na hydrolysis na polyester polyurethane, ana kuma ƙara abubuwan ƙari, kamar ƙara 1% phenolic antioxidant Irganox1010 zuwa PTMEG polyether elastomer. Ana iya ƙara ƙarfin ƙarfin wannan elastomer da sau 3-5 idan aka kwatanta da ba tare da antioxidants (sakamakon gwaji bayan tsufa a 1500C na sa'o'i 168). Amma ba kowane antioxidant yana da tasiri akan polyurethane elastomers, kawai phenolic 1rganox 1010 da TopanOl051 (antioxidant phenolic, hana amine haske stabilizer, benzotriazole hadaddun) suna da tasiri mai mahimmanci, kuma tsohon shine mafi kyau, mai yiwuwa saboda phenolic antioxidants suna da dacewa mai kyau tare da elastomers. Duk da haka, saboda muhimmiyar rawa na kungiyoyin phenolic hydroxyl a cikin tsarin daidaitawa na antioxidants phenolic, don kauce wa amsawa da "raguwa" na wannan rukunin phenolic hydroxyl tare da ƙungiyoyin isocyanate a cikin tsarin, rabon isocyanates zuwa polyols bai kamata ya kasance ba. ya yi girma sosai, kuma dole ne a ƙara antioxidants zuwa prepolymers da masu haɓaka sarƙoƙi. Idan aka kara a lokacin samar da prepolymers, zai tasiri tasiri sosai.
Abubuwan da ake amfani da su don hana hydrolysis na polyester polyurethane elastomers sune mafi yawan mahadi na carbodiimide, wanda ke amsawa tare da acid carboxylic da aka samar ta hanyar ester hydrolysis a cikin kwayoyin elastomer na polyurethane don samar da abubuwan da suka samo asali na acyl urea, hana ƙarin hydrolysis. Bugu da kari na carbodiimide a wani babban juzu'i na 2% zuwa 5% na iya kara yawan ruwa na polyurethane sau 2-4. Bugu da kari, tert butyl catechol, hexamethylenetetramine, azodicarbonamide, da dai sauransu suma suna da wasu tasirin antihydrolysis.
04 Babban halayen aiki
Polyurethane elastomers ne na hali Multi block copolymers, tare da kwayoyin sarƙoƙi hada da sassauƙa sassa tare da gilashin canji zafin jiki ƙasa da dakin zafin jiki da m segments tare da gilashin canji zafin jiki sama da dakin zafin jiki. Daga cikin su, polyols oligomeric suna samar da sassa masu sassauƙa, yayin da diisocyanates da ƙananan sarkar kwayoyin halitta ke samar da sassa masu tsauri. Tsarin da aka haɗa na sassa sassauƙa da sarƙaƙƙiya masu tsauri yana ƙayyadaddun ayyukansu na musamman:
(1) Matsakaicin taurin roba na yau da kullun yana tsakanin Shaoer A20-A90, yayin da kewayon taurin filastik shine game da Shaoer A95 Shaoer D100. Polyurethane elastomers na iya kaiwa ƙasa kamar Shaoer A10 kuma sama da Shaoer D85, ba tare da buƙatar taimakon filler ba;
(2) Ƙarfafa ƙarfi da haɓakawa har yanzu ana iya kiyaye su a cikin kewayon tauri mai yawa;
(3) Kyakkyawan juriya na lalacewa, 2-10 sau na roba na halitta;
(4) Kyakkyawan juriya ga ruwa, mai, da sinadarai;
(5) Babban tasiri mai tasiri, juriya na gajiya, da juriya na girgiza, dace da aikace-aikacen lankwasa mai girma;
(6) Kyakkyawan juriya mai ƙarancin zafin jiki, tare da ƙarancin zafin jiki a ƙasa -30 ℃ ko -70 ℃;
(7) Yana da kyakkyawan aikin haɓakawa, kuma saboda ƙarancin ƙarancin zafin jiki, yana da sakamako mafi kyau idan aka kwatanta da roba da filastik;
(8) Kyakkyawan biocompatibility da anticoagulant Properties;
(9) Kyakkyawan rufin lantarki, juriya, da kwanciyar hankali UV.
Ana iya samar da elastomers na polyurethane ta amfani da matakai iri ɗaya da na roba na yau da kullun, kamar filastik, hadawa, da vulcanization. Hakanan ana iya yin su a cikin nau'in roba na ruwa ta hanyar zubawa, gyare-gyaren tsakiya, ko fesa. Hakanan ana iya sanya su cikin kayan granular kuma a samar da su ta amfani da allura, extrusion, birgima, gyare-gyaren busa, da sauran matakai. Ta wannan hanyar, ba wai kawai yana inganta ingantaccen aiki ba, har ma yana inganta daidaiton girman da bayyanar samfurin.
Lokacin aikawa: Dec-05-2023