Icyo bitapolyurethaneni incamake ya polyurethane, ikorwa n'uburyo polyisocyanates na polyols zikora, kandi ikubiyemo amatsinda menshi ya amino ester asubirwamo (- NH-CO-O -) ku muyoboro wa molekile. Mu miyoboro ya polyurethane ikorwa, uretse itsinda rya amino ester, hari n'amatsinda nka urea na biuret. Polyols zigize molekile z'umuyoboro muremure zifite amatsinda ya hydroxyl ku iherezo, zitwa "uduce tw'umuyoboro woroshye", mu gihe polyisocyanates zitwa "uduce tw'umuyoboro ukomeye".
Mu ma resine ya polyurethane akorwa n'uduce tw'iminyururu yoroshye n'ikomeye, igice gito gusa ni cyo kigizwe na aside amine esters, bityo bishobora kuba bidakwiye kubyita polyurethane. Muri rusange, polyurethane ni inyongera ya isocyanate.
Ubwoko butandukanye bwa isocyanati bukorana na polyhydroxy compounds kugira ngo bukore imiterere itandukanye ya polyurethane, bityo bugakuramo ibikoresho bya polymer bifite imiterere itandukanye, nka pulasitiki, rubber, coating, fibres, kole, nibindi. Rubber ya polyurethane
Rubber ya polyurethane ikomoka ku bwoko bwihariye bwa rubber, bukorwa hakoreshejwe polyether cyangwa polyester irimo isocyanate. Hari ubwoko bwinshi bitewe n'ubwoko butandukanye bw'ibikoresho fatizo, imiterere y'ikoreshwa ry'ibicuruzwa, n'uburyo bwo guhuza. Ukurikije imiterere y'imiti, hari ubwoko bwa polyester na polyether, kandi ukurikije uburyo bwo gutunganya, hari ubwoko butatu: ubwoko bwo kuvanga, ubwoko bwo gukata, n'ubwoko bwa thermoplastic.
Rubber ya polyurethane ikoze muri sintetike ikorwa hakoreshejwe polyester cyangwa polyether ikoresheje diisocyanate kugira ngo hakorwe prepolymer ifite uburemere buke bwa molekile, hanyuma igashyirwamo reaction yo kwagura urunigi kugira ngo hakorwe polymer ifite uburemere bwinshi bwa molekile. Hanyuma, ibikoresho bikwiye byo guhuza bikongerwamo kandi bigashyushya kugira ngo bivurwe, bigahinduka rubber ya vulcanized. Ubu buryo bwitwa prepolymerization cyangwa uburyo bw'intambwe ebyiri.
Birashoboka kandi gukoresha uburyo bw'intambwe imwe - kuvanga polyester cyangwa polyether isanzwe hamwe na diisocyanates, imiyoboro y'uruhererekane, n'ibintu bihuza kugira ngo hatangwe reaction no gukora polyurethane rubber.
Igice cya A muri molekile za TPU gituma iminyururu ya macromolecular yoroshye kuzunguruka, iha rubber ya polyurethane uburimbane bwiza, igagabanya aho yoroshya n'aho ihindura imiterere ya polymer, kandi ikagabanya ubukana bwayo n'imbaraga zayo. Igice cya B kizahuza iminyururu ya macromolecular, bigatuma aho yoroshya n'aho ihindura imiterere ya polymer byiyongera, bigatuma uburimbane n'imbaraga za mashini byiyongera, ndetse no kugabanuka kw'uburimbane. Mu guhindura ikigereranyo cya molar hagati ya A na B, TPU zifite imiterere itandukanye ya mashini zishobora gukorwa. Imiterere ya TPU igomba kudatekereza gusa ku guhuza kw'ibanze, ahubwo no ku guhuza kw'ibanze gukozwe n'iminyururu ya hydrogen hagati ya molekile. Umunyururu wa polyurethane uhuza w'ibanze utandukanye n'imiterere ya vulcanization ya rubber ya hydroxyl. Itsinda ryayo rya amino ester, itsinda rya biuret, itsinda rya urea formate n'andi matsinda y'imikorere ateguwe mu gice cy'umunyururu uhoraho kandi ugororotse, bigatuma imiterere ya rubber ihuza neza, ifite ubushobozi bwo kudashira neza n'indi miterere myiza. Icya kabiri, bitewe n’uko hari amatsinda menshi y’imikorere ahuza cyane nka urea cyangwa carbamate muri polyurethane rubber, imigozi ya hydrogen ikorwa hagati y’imigozi ya molekile ifite imbaraga nyinshi, kandi imigozi ya kabiri ihuza ikorwa n’imigozi ya hydrogen nayo igira ingaruka zikomeye ku miterere ya polyurethane rubber. Imigozi ya kabiri ihuza ifasha polyurethane rubber kugira imiterere ya thermosetting elastomers ku ruhande rumwe, kandi ku rundi ruhande, iyi migozi ntabwo ihuza koko, bigatuma iba imigozi ihuza. Imiterere y’imigozi iterwa n’ubushyuhe. Uko ubushyuhe bwiyongera, iyi migozi iragabanuka buhoro buhoro ikabura. Polymeri ifite fluidity runaka kandi ishobora gukorerwa thermoplastic. Iyo ubushyuhe bugabanutse, iyi migozi iragaruka buhoro buhoro ikarema. Kongeramo agace gato k’umunyururu byongera intera iri hagati ya molekile, bigaca intege ubushobozi bwo gukora imigozi ya hydrogen hagati ya molekile, kandi bigatera kugabanuka gukabije kw’imbaraga. Ubushakashatsi bwagaragaje ko urutonde rw’imigozi itandukanye y’imikorere muri polyurethane rubber kuva hejuru kugeza hasi ari: ester, ether, urea, carbamate, na biuret. Mu gihe cyo gusaza kwa polyurethane rubber, intambwe ya mbere ni ugucika kw'imigozi ihuza biuret na urea, hagakurikiraho gucika kw'imigozi ya carbamate na urea, ni ukuvuga umunyururu mukuru ucika.
01 Koroshya
Elastome za polyurethane, kimwe n'ibindi bikoresho byinshi bya polymer, zoroha iyo ubushyuhe bwinshi bukabije kandi zigahinduka kuva ku rugero rwo guhindagurika zijya ku rugero rwo guhindagurika, bigatuma imbaraga za mekanike zigabanuka vuba. Mu rwego rwa shimi, ubushyuhe bwo guhindagurika buterwa ahanini n'ibintu nk'imiterere yabyo, uburemere bwa molekile, n'ubucucike bw'imirongo.
Muri rusange, kongera uburemere bwa molekile, kongera ubukana bw'igice gikomeye (nko kwinjiza impeta ya benzene muri molekile) n'ibikubiye mu gice gikomeye, no kongera ubucucike bw'ibice bihuza byose ni ingirakamaro mu kongera ubushyuhe bwo koroshya. Kuri elastomer za thermoplastic, imiterere ya molekile iba ishingiye ku murongo, kandi ubushyuhe bwo koroshya bwa elastomer nabwo buriyongera iyo uburemere bwa molekile bwiyongerewe.
Ku bijyanye na elastome za polyurethane zifatanye, ubucucike bw'ibice bifatanye bigira ingaruka zikomeye kuruta uburemere bwa molekile. Kubwibyo, iyo ukoze elastome, kongera imikorere ya isocyanates cyangwa polyols bishobora gukora imiterere y'ibinyabutabire bihuza ubushyuhe muri bimwe mu bice bifatanye, cyangwa gukoresha ikigereranyo cya isocyanates nyinshi kugira ngo habeho imiterere ihamye ya isocyanates mu mubiri ufatanye ni uburyo bukomeye bwo kunoza ubushobozi bwo kurwanya ubushyuhe, kurwanya solvent, n'imbaraga za mekanike za elastome.
Iyo PPDI (p-phenyldisocyanate) ikoreshejwe nk'ibikoresho fatizo, bitewe n'isano itaziguye hagati y'amatsinda abiri ya isocyanate n'impeta ya benzene, igice gikomeye cyakozwe kiba gifite impeta nyinshi ya benzene, ibyo bigatuma igice gikomeye kirushaho gukomera bityo bikongera ubushyuhe bwa elastomer.
Urebye mu buryo bw'umubiri, ubushyuhe bwo koroshya bwa elastomer buterwa n'urugero rw'itandukaniro rya microphase. Nk'uko raporo zibivuga, ubushyuhe bwo koroshya bwa elastomer zidakoresha microphase ni buke cyane, aho ubushyuhe bwo gutunganya bugera kuri 70 ℃ gusa, mu gihe elastomer zikoresha microphase zishobora kugera kuri 130-150 ℃. Kubwibyo, kongera urugero rw'itandukaniro rya microphase muri elastomer ni bumwe mu buryo bwiza bwo kunoza ubushyuhe bwazo.
Urugero rw'itandukaniro rya microphase rya elastomers rushobora kunozwa binyuze mu guhindura ingano y'uburemere bwa molekile mu bice by'urunigi n'ingano y'ibice by'urunigi bikomeye, bityo bikongera ubushobozi bwabyo bwo kurwanya ubushyuhe. Abashakashatsi benshi bemeza ko impamvu yo gutandukana kwa microphase muri polyurethane ari ukudahuza kwa thermodynamic hagati y'ibice byoroshye n'ibikomeye. Ubwoko bw'umuyoboro w'urunigi, igice gikomeye n'ibirimo, ubwoko bw'ibice byoroshye, hamwe n'imibanire ya hydrogen byose bigira ingaruka zikomeye kuri byo.
Ugereranije n’udukoresho twongera umunyururu wa diol, udukoresho twongera umunyururu wa diamine nka MOCA (3,3-dichloro-4,4-diaminodiphenylmethane) na DCB (3,3-dichloro-biphenylenediamine) bikora amatsinda menshi ya amino ester muri elastomers, kandi imigozi myinshi ya hydrogen ishobora gukorwa hagati y’uduce dukomeye, byongera imikoranire hagati y’uduce dukomeye no kunoza urwego rw’itandukaniro rya microphase muri elastomers; Udukoresho twongera umunyururu wa aromatike nka p, p-dihydroquinone, na hydroquinone ni ingirakamaro mu guhuza no gupakira neza uduce dukomeye, bityo bikanoza itandukaniro rya microphase ry’ibicuruzwa.
Ibice bya amino ester bigizwe na aliphatic isocyanates bihura neza n'ibice byoroshye, bigatuma ibice bikomeye byinshi bishonga mu bice byoroshye, bigabanura urugero rw'itandukaniro rya microphase. Ibice bya amino ester bigizwe na aromatic isocyanates ntibihura neza n'ibice byoroshye, mu gihe urugero rw'itandukaniro rya microphase ruri hejuru. Polyolefin polyurethane ifite imiterere hafi ya yose yo gutandukanya microphase bitewe nuko igice cyoroshye kidakora imigozi ya hydrogen kandi imigozi ya hydrogen ishobora kubaho gusa mu gice gikomeye.
Ingaruka zo guhuza hydrogen ku ngingo yoroshye ya elastomer nazo ni ingenzi. Nubwo polyether na karuboneli mu gice cyoroshye bishobora gukora umubare munini w'imigozi ya hydrogen hamwe na NH mu gice gikomeye, binatuma ubushyuhe bworoshye bwa elastomer burushaho koroha. Byemejwe ko imigozi ya hydrogen igifite 40% kuri 200 ℃.
02 Gushonga kw'ubushyuhe
Amatsinda ya amino ester ahura n'ihindagurika rikurikira ku bushyuhe bwinshi:
- RNHCOOR – RNC0 HO-R
- RNHCOOR – RNH2 CO2 ene
- RNHCOOR – RNHR CO2 ene
Hari ubwoko butatu bw'ingenzi bwo gusenya ubushyuhe bw'ibikoresho bishingiye kuri polyurethane:
① Gukora isocyanates na polyols by'umwimerere;
② α— Umugozi wa ogisijeni ku ishingiro rya CH2 uracikamo kabiri, ugahuzwa n'umugozi umwe wa hydrogen kuri CH2 ya kabiri, bigakorwa aside amine na alkene. Aside amine zibora zikavamo amine imwe y'ibanze na dioxyde de carbone:
③ Igizwe na amine ya kabiri ya 1 na dioxyde de carbone.
Uburyo bwo gushonga kw'ubushyuhe bw'imiterere ya kabamate:
Aryl NHCO Aryl, ~ 120 ℃;
N-alkyl-NHCO-aryl, ~ 180 ℃;
Aryl NHCO n-alkyl, ~ 200 ℃;
Ubushyuhe bwa N-alkyl-NHCO-n-alkyl, ~ 250 ℃.
Ubushyuhe bw'ibipimo bya aside amine buterwa n'ubwoko bw'ibikoresho byo gutangira nka isocyanates na polyols. Isocyanates za Aliphatic ziri hejuru ya isocyanates zirangwa n'amarangi, mu gihe alcool zirimo ibinure ziri hejuru ya alcools zirangwa n'amarangi. Nyamara, inyandiko zivuga ko ubushyuhe bw'ubushyuhe bwa aliphatic aside amine esters buri hagati ya 160-180 ℃, naho ubushyuhe bwa aside amine esters burangwa n'amarangi buri hagati ya 180-200 ℃, ibi bikaba bidahuye n'amakuru yavuzwe haruguru. Impamvu ishobora kuba ifitanye isano n'uburyo bwo gupima.
Mu by’ukuri, CHDI ya aliphatic (1,4-cyclohexane diisocyanate) na HDI (hexamethylene diisocyanate) bifite ubushobozi bwo kurwanya ubushyuhe kurusha MDI na TDI bikunze gukoreshwa. Cyane cyane CHDI ya trans ifite imiterere ingana yamenyekanye nk'isocyanate irwanya ubushyuhe cyane. Elastome za polyurethane zakozwe muri yo zifite ubushobozi bwo gutunganya neza, zirwanya hydrolysis nziza, ubushyuhe bwinshi bwo koroshya, ubushyuhe buke bwo guhindura ikirahuri, hysteresis nke y'ubushyuhe, kandi zirwanya UV nyinshi.
Uretse itsinda rya amino ester, polyurethane elastomers ifite n'andi matsinda akora nka urea formate, biuret, urea, n'ibindi. Aya matsinda ashobora kubora ubushyuhe ku bushyuhe bwinshi:
NHCONCOO – (formate ya alifatiki ya urea), 85-105 ℃;
- NHCONCOO – (formate y'umunyu wa urea), ku bushyuhe buri hagati ya 1-120 ℃;
- NHCONCONH – (aliphatic biuret), ku bushyuhe buri hagati ya 10 ° C na 110 ° C;
NHCONCONH – (biuret ihumura neza), 115-125 ℃;
NHCONH – (aliphatic urea), 140-180 ℃;
- NHCONH – (umunyu urea), 160-200 ℃;
Impeta ya Isocyanurate > 270 ℃.
Ubushyuhe bwo kubora ubushyuhe bwa biuret na urea formate bushingiye kuri urea buri hasi cyane ugereranyije n'ubwa aminoformate na urea, mu gihe isocyanurate ifite ubushyuhe bwiza cyane. Mu gukora elastome, isocyanates nyinshi zishobora kongera gukorana na aminoforme na urea byakozwe kugira ngo bikore imiterere ishingiye kuri urea na biurete. Nubwo zishobora kunoza imiterere ya elastome, ntabwo zihindagurika cyane ku bushyuhe.
Kugira ngo ugabanye amatsinda adafite ubushyuhe buhagije nka biuret na urea formate muri elastomer, ni ngombwa gusuzuma ingano y'ibikoresho fatizo byabyo n'uburyo bikorerwa. Hagomba gukoreshwa ingano nyinshi ya isocyanate, kandi hagakoreshwa ubundi buryo bushoboka kugira ngo habeho impeta za isocyanate mu bikoresho fatizo (cyane cyane isocyanate, polyols, na chain extenders), hanyuma ukazishyira muri elastomer hakurikijwe inzira zisanzwe. Ubu bwabaye uburyo bukoreshwa cyane mu gukora elastomer za polyurethane zirwanya ubushyuhe kandi zirwanya umuriro.
03 Hydrolysis na oxidation y'ubushyuhe
Elastomeri za polyurethane zikunze kwangirika mu bice byazo bikomeye ndetse n'impinduka zijyanye na shimi mu bice byazo byoroshye mu bushyuhe bwinshi. Elastomeri za polyester zifite ubushobozi buke bwo kudakoresha amazi kandi zikunda gushonga cyane mu bushyuhe bwinshi. Igihe cy'ubuzima bwa polyester/TDI/diamine gishobora kugera ku mezi 4-5 kuri 50 ℃, ibyumweru bibiri gusa kuri 70 ℃, n'iminsi mike gusa hejuru ya 100 ℃. Ester bonds zishobora kwangirika mu buryo bujyanye na aside na alcool iyo zihuye n'amazi ashyushye n'umwuka, kandi amatsinda ya urea na amino ester muri elastomeri na yo ashobora guhura n'ingaruka za hydrolysis:
RCOOR H20- → RCOOH HOR
Inzoga ya Ester
RNHCONHR imwe H20- → RXHCOOH H2NR -
Ureamide
RNHCOOR imwe-H20- → RNCOOH HOR -
Amino formate ester Amino formate alcohol
Elastomeri zishingiye kuri polyether zifite ubushobozi buke bwo kudakoresha ubushyuhe, naho elastomeri zishingiye kuri ether α- Hydrogen iri kuri atome ya karuboni irahinduka oxidation byoroshye, igakora peroxide ya hydrogen. Nyuma yo kubora no gucikamo ibice, ikora oxidation ya oxide na hydroxyl radicals, amaherezo zigahinduka formates cyangwa aldehydes.
Polyester zitandukanye zigira ingaruka nke ku bushyuhe bwa elastomer, mu gihe polyether zitandukanye zifite ingaruka runaka. Ugereranyije na TDI-MOCA-PTMEG, TDI-MOCA-PTMEG ifite igipimo cyo kugumana imbaraga zo gukurura cya 44% na 60% uko bikurikirana iyo imaze iminsi 7 iri ku bushyuhe bwa 121 ℃, aho iya nyuma iba nziza cyane kurusha iya mbere. Impamvu ishobora kuba ari uko molekile za PPG zifite iminyururu y'amashami, idafasha mu miterere isanzwe ya molekile za elastomer kandi ikagabanya ubushyuhe bw'umubiri wa elastomer. Uburyo bwo guhagarara kw'ubushyuhe bwa polyethers ni: PTMEG>PEG>PPG.
Andi matsinda akora muri elastome za polyurethane, nka urea na carbamate, na yo ahura n'ingaruka za oxidation na hydrolysis. Ariko, itsinda rya ether ni ryo ryoroshye gukurwamo oxidation, mu gihe itsinda rya ester ari ryo ryoroshye gukurwamo hydrolysis. Uko antioxidant na hydrolysis zabo zirwanya ni:
Umurimo wa antioxydants: esters>urea>carbamate>ether;
Ubudahangarwa bwa Hydrolysis: ester
Kugira ngo hongerwe uburyo bwo kurwanya ogisijeni ya polyether polyurethane no kurwanya hydrolysis ya polyester polyurethane, hongerwamo inyongera, nko kongeramo 1% ya phenolic antioxidant Irganox1010 kuri PTMEG polyether elastomer. Ingufu zo gukurura iyi elastomer zishobora kwiyongeraho inshuro 3-5 ugereranije n'izidafite antioxydants (ibisubizo nyuma yo gusaza kuri 1500C mu masaha 168). Ariko si antioxydants zose zigira ingaruka kuri polyurethane elastomers, phenolic 1rganox 1010 na TopanOl051 gusa (phenolic antioxidant, hifashishijwe amine light stabilizer, benzotriazole complex) bigira ingaruka zikomeye, kandi iya mbere ni yo nziza, wenda kubera ko antioxydants za phenolic zihuye neza na elastomer. Ariko, bitewe n'uruhare runini rw'amatsinda ya phenolic hydroxyl mu buryo bwo gutuza antioxydants za phenolic, kugira ngo hirindwe ingaruka n' "kunanirwa" kw'iri tsinda rya phenolic hydroxyl hamwe n'amatsinda ya isocyanate muri sisitemu, igipimo cya isocyanate na polyols ntikigomba kuba kinini cyane, kandi antioxydants zigomba kongerwa kuri prepolymers na chain extenders. Iyo zongeweho mu gihe cyo gukora prepolymers, bizagira ingaruka zikomeye ku ngaruka zo gutuza.
Inyongeramusaruro zikoreshwa mu gukumira hydrolysis ya polyester polyurethane elastomers ahanini ni ibintu bya carbodiimide, bikorana na aside carboxylic zikorwa na ester hydrolysis muri molekile za polyurethane elastomer kugira ngo bikore derivatives za acyl urea, bikarinda hydrolysis kurushaho. Kongeramo carbodiimide ku gipimo cya 2% kugeza kuri 5% bishobora kongera ubushobozi bwo kugumana amazi ya polyurethane inshuro 2-4. Byongeye kandi, tert butyl catechol, hexamethylenetetramine, azodicarbonamide, nibindi nabyo bigira ingaruka zimwe na zimwe zo kurwanya hydrolysis.
04 Ibiranga imikorere y'ingenzi
Elastomer za polyurethane ni copolymer zisanzwe zifite ibice byinshi, zifite iminyururu ya molekile igizwe n'ibice byoroshye bifite ubushyuhe bw'impinduka y'ikirahure buri munsi y'ubushyuhe bw'icyumba n'ibice bikomeye bifite ubushyuhe bw'impinduka y'ikirahure buri hejuru y'ubushyuhe bw'icyumba. Muri byo, polyol za oligomeric zikora ibice byoroshye, mu gihe diisocyanates n'uduce duto tw'iminyururu birema ibice bikomeye. Imiterere y'ibice byoroshye kandi bikomeye igena imikorere yabyo yihariye:
(1) Uburemere bw'ubukomere bwa rubber isanzwe muri rusange buri hagati ya Shaoer A20-A90, mu gihe uburemere bwa pulasitiki buri hafi ya Shaoer A95 Shaoer D100. Elastomer za polyurethane zishobora kugera kuri Shaoer A10 no hejuru nka Shaoer D85, hatabayeho ubufasha bwo kuzuza;
(2) Ingufu nyinshi n'ubudahangarwa bishobora gukomeza gukoreshwa mu buryo butandukanye;
(3) Ubudahangarwa bwiza bwo kwangirika, inshuro 2-10 z'umupira w'umwimerere;
(4) Ubudahangarwa bwiza ku mazi, amavuta, n'imiti;
(5) Ubudahangarwa bukomeye, ubudahangarwa, no kudahangarwa n'imitingito, bikwiriye gukoreshwa mu buryo bworoshye bwo gupfunyika;
(6) Ubudahangarwa bwiza ku bushyuhe buri hasi, hamwe n'ubushyuhe buri hasi y'ubushyuhe buri munsi ya -30 ℃ cyangwa -70 ℃;
(7) Ifite ubushobozi bwo gukingira neza, kandi kubera ko ifite ubushobozi buke bwo gutwara ubushyuhe, ifite ubushobozi bwo gukingira neza ugereranije na lab na pulasitiki;
(8) Imiterere myiza yo guhuza imiterere y'umubiri n'imiti igabanya amaraso;
(9) Gukingira neza amashanyarazi, kurwanya ibishishwa, no kudahindagurika kw'imirasire y'urumuri.
Elastome za polyurethane zishobora gukorwa hakoreshejwe uburyo bumwe n’uburyo busanzwe bwo gukora irangi, nko gukoresha pulasitiki, kuvanga no gukoresha vulcanization. Zishobora kandi gutegurwa mu buryo bwa rubber y’amazi hakoreshejwe gusuka, gukoresha centrifugal molding, cyangwa gukoresha spray. Zishobora kandi gukorwamo ibikoresho by’ibinyabutabire hanyuma zigakorwa hakoreshejwe injection, extrusion, villing, blow molding, n’izindi nzira. Muri ubu buryo, ntibwongera gusa imikorere myiza, ahubwo bunanongera imiterere y’ibicuruzwa n’isura yabyo.
Igihe cyo kohereza: Ukuboza-05-2023