Zvinonzipolyurethaneipfupiso ye polyurethane, iyo inoumbwa nekuita kwe polyisocyanates ne polyols, uye ine mapoka akawanda e amino ester anodzokororwa (- NH-CO-O -) pa molecular chain. Muma polyurethane resins chaiwo akagadzirwa, kuwedzera kuboka re amino ester, kunewo mapoka akadai se urea ne biuret. Polyols ndeye ma long-chain molecules ane hydroxyl groups kumagumo, ayo anonzi "soft chain segments", nepo polyisocyanates achinzi "hard chain segments".
Pakati pema polyurethane resin anogadzirwa nezvikamu zvecheni dzakapfava uye dzakaoma, chikamu chidiki chete ndicho chine ma amino acid esters, saka zvingasava zvakakodzera kuati polyurethane. Mupfungwa yakafara, polyurethane chinhu chinowedzera isocyanate.
Mhando dzakasiyana dzeisocyanates dzinoita zvinoenderana nepolyhydroxy compounds kuti dzigadzire maumbirwo akasiyana epolyurethane, nokudaro dzichiwana zvinhu zvepolymer zvine hunhu hwakasiyana, zvakaita semapurasitiki, rabha, machira, machira, manamati, nezvimwewo. Rabha yepolyurethane
Rabha yepolyurethane ndeyemhando yakasarudzika yerabha, iyo inogadzirwa ne polyether kana polyester inogadzirisa ne isocyanate. Kune mhando dzakawanda nekuda kwemhando dzakasiyana dzezvinhu zvisina kugadzirwa, mamiriro ekuita, uye nzira dzekubatanidza. Kubva pamaonero ekugadzirwa kwemakemikari, kune mhando dzepolyester ne polyether, uye kubva pamaonero enzira yekugadzirisa, kune mhando nhatu: mhando yekusanganisa, mhando yekukanda, uye mhando yethermoplastic.
Rabha yepolyurethane yakagadzirwa inowanzogadzirwa nepolyester yakatsetseka kana polyether ine diisocyanate kuti igadzire prepolymer ine huremu hwakaderera, iyo inozoiswa muketani yekuwedzera kuti igadzire polymer ine huremu hwakakwira. Zvadaro, zvinhu zvakakodzera zvinobatanidzwa zvinowedzerwa uye zvinodziiswa kuti zviigadziriswe, zvichiita kuti ive rabha yakanyungudutswa. Nzira iyi inonzi prepolymerization kana nzira yematanho maviri.
Zvinokwanisikawo kushandisa nzira imwe chete - kusanganisa zvakananga linear polyester kana polyether ne diisocyanates, chain extenders, uye crosslinking agents kuti pave ne reaction uye kugadzira polyurethane rabha.
Chikamu cheA muTPU molecules chinoita kuti macromolecular chains ave nyore kutenderedza, zvichiita kuti polyurethane rabha ive nyore kutenderedza, ichideredza softening point uye secondary transition point yepolymer, uye ichideredza kuoma kwayo uye simba remakanika. Chikamu cheB chichabatanidza kutenderera kwemacromolecular chains, zvichiita kuti softening point uye secondary transition point yepolymer iwedzere, zvichikonzera kuwedzera kwekuoma uye simba remakanika, uye kudzikira kwekuoma. Nekugadzirisa molar ratio pakati paA naB, maTPU ane hunhu hwakasiyana hwemakanika anogona kugadzirwa. Maumbirwo eTPU haafanire kungofunga nezve primary cross-linking, asiwo secondary cross-linking inoumbwa nehydrogen bonds pakati pemamorekuru. Primary cross-linking bond yepolyurethane yakasiyana ne vulcanization structure ye hydroxyl raber. Amino ester group yayo, biuret group, urea formate group nedzimwe functional groups dzakarongwa mu regular and spaced rigid chain segment, zvichikonzera regular network structure yerabha, ine highly wear resistance uye mamwe hunhu hwakanaka. Chechipiri, nekuda kwekuvapo kwemapoka akawanda anoshanda pamwe chete akadai se urea kana carbamate groups mu polyurethane rabber, hydrogen bonds inoumbwa pakati pemamorecular chains ine simba guru, uye secondary crosslinking bonds inoumbwa nehydrogen bonds inewo simba guru pahunhu hwe polyurethane rabber. Secondary cross-linking inogonesa polyurethane rabber kuva nehunhu hwe thermosetting elastomers kune rumwe rutivi, uye kune rumwe rutivi, cross-linking iyi haina cross-linked zvechokwadi, zvichiita kuti ive virtual cross-linking. Mamiriro e cross-linking anoenderana nekupisa. Sezvo tembiricha ichiwedzera, cross-linking iyi inoderera zvishoma nezvishoma uye inonyangarika. Polymer ine fluidity yakati uye inogona kuiswa mu thermoplastic processing. Kana tembiricha yadzikira, cross-linking iyi inodzoka zvishoma nezvishoma uye inoumbwa zvakare. Kuwedzera kwechikamu chidiki che filler kunowedzera daro pakati pemamorekuru, kunoderedza kugona kwekugadzira hydrogen bonds pakati pemamorekuru, uye kunotungamira kudzikira kwakanyanya kwesimba. Tsvagiridzo yakaratidza kuti kurongeka kwekugadzikana kwemapoka akasiyana-siyana anoshanda mu polyurethane rabber kubva kumusoro kusvika pasi ndekwekuti: ester, ether, urea, carbamate, uye biuret. Munguva yekukwegura kwerabha yepolyurethane, danho rekutanga kutyorwa kwezvisungo zvinobatanidza biuret neurea, zvichiteverwa nekutyorwa kwezvisungo zvecarbamate neurea, kureva kuti, kutyorwa kwecheni huru.
01 Kunyorovesa
Ma elastomer epolyurethane, sezvimwe zvinhu zvakawanda zve polymer, anonyorova pakupisa kwakanyanya uye anochinja kubva pa elastic state kuenda ku viscous flow state, zvichikonzera kudzikira kwesimba remakanika nekukurumidza. Kubva pamaonero emakemikari, tembiricha inonyorova ye elasticity inonyanya kutsamira pazvinhu zvakaita se chemical composition yayo, relative molecular weight, uye crosslinking density.
Kazhinji, kuwedzera huremu hwemamorekuru, kuwedzera kuomarara kwechikamu chakaoma (sekupinza benzene ring mumorekuru) uye zviri mukati mechikamu chakaoma, uye kuwedzera huwandu hwe crosslinking zvese zvinobatsira pakuwedzera tembiricha inonyorovesa. Kune ma thermoplastic elastomers, chimiro chemorekuru chinonyanya kurongeka, uye tembiricha inonyorovesa ye elastomer inowedzerawo kana huremu hwemorekuru hwakawedzerwa.
Kune ma-elastomer epolyurethane akabatana, kuwanda kwekubatanidza kune simba guru kupfuura huremu hwemamorekuru. Nokudaro, pakugadzira ma-elastomer, kuwedzera mashandiro ema-isocyanates kana ma-polyol kunogona kugadzira chimiro chekubatanidza chemakemikari chenetwork chakasimba mune mamwe mamorekuru e-elastic, kana kushandisa zviyero zvakawandisa zve-isocyanate kugadzira chimiro chekubatanidza che-isocyanate chakasimba mumuviri we-elastic inzira ine simba yekuvandudza kuramba kupisa, kuramba solvent, uye simba remagetsi re-elastomer.
Kana PPDI (p-phenyldisocyanate) ikashandiswa sezvinhu zvakagadziriswa, nekuda kwekubatana kwakananga kwemapoka maviri eisocyanate nemhete yebenzene, chikamu chakaoma chakagadzirwa chine huwandu hwakawanda hwemhete yebenzene, izvo zvinovandudza kuomarara kwechikamu chakaoma uye nokudaro zvinowedzera kuramba kupisa kwe elastomer.
Kubva pamaonero emuviri, tembiricha yekupfava kwema elastomers inoenderana nedanho rekupatsanurwa kwe microphase. Sekureva kwemishumo, tembiricha yekupfava yema elastomers asingapfuure nekupatsanurwa kwe microphase yakaderera zvikuru, netembiricha yekugadzirisa inosvika 70 ℃ chete, nepo ma elastomers anopfuure nekupatsanurwa kwe microphase anogona kusvika 130-150 ℃. Nokudaro, kuwedzera mwero wekupatsanurwa kwe microphase muma elastomers ndeimwe yenzira dzinoshanda dzekuvandudza kudzivirira kwavo kupisa.
Kupatsanurwa kwema elastomers muchikamu che microphase kunogona kuvandudzwa nekuchinja kugoverwa kwehuremu hwema molecular muzvikamu zve chain uye zviri mukati mezvikamu zve chain zvakasimba, nokudaro zvichiwedzera kuramba kwavo kupisa. Vaongorori vazhinji vanotenda kuti chikonzero chekupatsanurwa kwe microphase mu polyurethane ikusawirirana kwe thermodynamic pakati pezvikamu zvakapfava nezvine simba. Rudzi rwe chain extender, chikamu chakaoma uye zviri mukati mayo, rudzi rwechikamu chakapfava, uye hydrogen bonding zvese zvine simba guru pairi.
Zvichienzaniswa ne diol chain extenders, diamine chain extenders dzakadai seMOCA (3,3-dichloro-4,4-diaminodiphenylmethane) uye DCB (3,3-dichloro-biphenylenediamine) dzinoumba mapoka akawanda e polar amino ester mu elastomers, uye hydrogen bonds dzakawanda dzinogona kuumbwa pakati pezvikamu zvakaoma, zvichiwedzera kudyidzana pakati pezvikamu zvakaoma uye kuvandudza mwero wekuparadzaniswa kwe microphase mu elastomers; Symmetric aromatic chain extenders dzakadai se p, p-dihydroquinone, uye hydroquinone dzinobatsira pakugadzirisa uye kurongedza zvikamu zvakaoma, nokudaro zvichivandudza kuparadzaniswa kwe microphase kwezvigadzirwa.
Zvikamu zveamino ester zvinoumbwa ne aliphatic isocyanates zvinobatana zvakanaka nezvikamu zvakapfava, zvichikonzera kuti zvikamu zvakaoma zvakawanda zvinyungudike muzvikamu zvakapfava, zvichideredza mwero wekuparadzaniswa kwe microphase. Zvikamu zveamino ester zvinoumbwa ne aromatic isocyanates hazviwirirane zvakanaka nezvikamu zvakapfava, nepo mwero wekuparadzaniswa kwe microphase wakakwira. Polyolefin polyurethane ine chimiro chekuparadzanisa microphase chakakwana nekuda kwekuti chikamu chakapfava hachiumbi hydrogen bonds uye hydrogen bonds inogona kungoitika muchikamu chakaoma.
Mhedzisiro yekusungana kwehydrogen papombi yekunyorovesa ye elastomers inokoshawo. Kunyangwe ma polyether nema carbonyls ari muchikamu chakapfava achigona kuumba huwandu hwakawanda hwezvisungo zvehydrogen neNH muchikamu chakaoma, zvinowedzerawo tembiricha yekunyorovesa ye elastomers. Zvakasimbiswa kuti zvisungo zvehydrogen zvichiri kuchengetedza 40% pa200 ℃.
02 Kuora kwekupisa
Mapoka eAmino ester anoora zvinotevera pakupisa kwakanyanya:
- RNHCOOR – RNC0 HO-R
- RNHCOOR – RNH2 CO2 ene
- RNHCOOR – RNHR CO2 ene
Kune mhando nhatu huru dzekuora kwekupisa kwezvinhu zvakagadzirwa ne polyurethane:
① Kugadzira ma isocyanates nema polyols ekutanga;
② α— Chisungo cheokisijeni chiri pachigadziko cheCH2 chinotyoka uye chinobatana nechisungo chimwe chete chehydrogen chiri paCH2 yechipiri kuti chigadzire maamino acids nemaalkenes. Maamino acids anoora kuita amine imwe chete yekutanga uye carbon dioxide:
③ Fomu 1 rechipiri amine uye kabhoni dhayokisaidhi.
Kuora kwechimiro checarbamate nekupisa:
Aryl NHCO Aryl,~120 ℃;
N-alkyl-NHCO-aryl,~180 ℃;
Aryl NHCO n-alkyl,~200 ℃;
N-alkyl-NHCO-n-alkyl,~250 ℃.
Kugadzikana kwekupisa kwemaamino acid esters kwakabatana nemhando dzezvinhu zvekutanga zvakaita seisocyanates nepolyols. Aliphatic isocyanates yakakwira kupfuura aromatic isocyanates, nepo fatty alcohols yakakwira kupfuura aromatic alcohols. Zvisinei, zvinyorwa zvinoshuma kuti tembiricha yekuora kwekupisa kwema aliphatic amino acid esters iri pakati pe160-180 ℃, uye yearomatic amino acid esters iri pakati pe180-200 ℃, izvo zvisingaenderane nedata riri pamusoro apa. Chikonzero chingave chakabatana nenzira yekuyedza.
Kutaura zvazviri, aliphatic CHDI (1,4-cyclohexane diisocyanate) neHDI (hexamethylene diisocyanate) zvine simba rekudzivirira kupisa kupfuura aromatic MDI neTDI. Kunyanya trans CHDI ine chimiro chakafanana yakaonekwa seisocyanate inodzivirira kupisa zvakanyanya. Polyurethane elastomers yakagadzirwa kubva mairi ine simba rekugadzirisa, inodzivirira hydrolysis zvakanaka, inonyorovesa zvakanyanya, tembiricha yakaderera yekuchinja kwegirazi, hysteresis yakaderera yekupisa, uye inodzivirira UV yakawanda.
Kuwedzera kune amino ester group, polyurethane elastomers inewo mamwe mapoka anoshanda akadai se urea formate, biuret, urea, nezvimwewo. Mapoka aya anogona kuora nekupisa pakupisa kwakanyanya:
NHCONCOO – (aliphatic urea formate), 85-105 ℃;
- NHCONCOO – (aromatic urea formate), patembiricha ye1-120 ℃;
- NHCONCONH – (aliphatic biuret), patembiricha inotangira pa10 ° C kusvika 110 ° C;
NHCONCONH – (inonhuhwirira biuret), 115-125 ℃;
NHCONH – (aliphatic urea), 140-180 ℃;
- NHCONH – (urea inonhuhwirira), 160-200 ℃;
Mhete yeIsocyanurate >270 ℃.
Tembiricha yekuora kwemafuta ekubiureti neurea yakaderera zvikuru pane yeaminoformate neurea, nepo isocyanurate ichiva nekugadzikana kwakanyanya kwemafuta ekubiureti. Mukugadzirwa kwe elastomers, ma isocyanates akawandisa anogona kuita zvimwe ne aminoformate neurea zvakagadzirwa kuti zvigadzire maumbirwo akabatana ne urea ne biuret. Kunyangwe zvichigona kuvandudza hunhu hwe elastomers, hadzina kugadzikana zvakanyanya pakupisa.
Kuti kuderedze mapoka asingagadzikane ekupisa akadai se biuret ne urea formate mu elastomers, zvakakosha kufunga nezve raw material ratio yavo uye maitiro ekugadzira. Excess isocyanate ratios dzinofanira kushandiswa, uye dzimwe nzira dzinofanira kushandiswa zvakanyanya sezvinobvira kutanga kugadzira partial isocyanate rings mu raw materials (kunyanya isocyanates, polyols, uye chain extenders), uye wozozvipinza mu elastomer zvichienderana nemaitiro akajairwa. Iyi yave nzira inonyanya kushandiswa yekugadzira polyurethane elastomers inodzivirira kupisa uye inodzivirira moto.
03 Hydrolysis uye kupisa
Ma polyurethane elastomers anowanzo ora nekupisa muzvikamu zvawo zvakaoma uye kuchinja kwemakemikari kunoenderana nezvikamu zvawo zvakapfava pakupisa kwakanyanya. Ma polyester elastomers haana simba rekudzivirira mvura uye anowanzo chinja hydrolyze pakupisa kwakanyanya. Hupenyu hwekushanda hwe polyester/TDI/diamine hunogona kusvika mwedzi 4-5 pa 50 ℃, mavhiki maviri chete pa 70 ℃, uye mazuva mashoma chete pamusoro pe 100 ℃. Ma Ester bonds anogona kuora kuita ma acids ne alcohols anoenderana kana akaiswa mumvura inopisa ne steam, uye mapoka e urea ne amino ester mu elastomers anogonawo kuita hydrolysis reactions:
RCOOR H20- → RCOOH HOR
Doro reEster
Imwe RNHCONHR imwe H20- → RXHCOOH H2NR -
Ureamide
Imwe RNHCOOR-H20- → RNCOOH HOR -
Amino formate ester Amino formate alcohol
Ma elastomer akavakirwa pa polyether haana kugadzikana kwekupisa, uye ma elastomer akavakirwa pa ether α- Hydrogen iri paatomu yekabhoni inogadziriswa nyore nyore, zvichiita hydrogen peroxide. Mushure mekuora nekutsemuka, inogadzira oxide radicals uye hydroxyl radicals, iyo inozopedzisira yaora kuita ma formates kana aldehydes.
Mapolyester akasiyana haana simba guru pakudzivirira kupisa kwe elastomers, nepo mapolyether akasiyana aine simba rakati. Kana tichienzanisa ne TDI-MOCA-PTMEG, TDI-MOCA-PTMEG ine simba rekuchengetedza re44% ne60% zvichiteerana kana yachembera pa121 ℃ kwemazuva manomwe, uye yekupedzisira iri nani zvakanyanya pane yekutanga. Chikonzero chingave chekuti mamorekuru ePPG ane macheni ane matavi, ayo asingakodzeri kurongeka kwemamorekuru e elastic uye anoderedza kudzivirira kupisa kwemuviri we elastic. Kurongeka kwekugadzikana kwekupisa kwe mapolyether ndekwekuti: PTMEG>PEG>PPG.
Mamwe mapoka anoshanda mu polyurethane elastomers, akadai se urea ne carbamate, anosanganawo ne oxidation uye hydrolysis reactions. Zvisinei, boka re ether ndiro rinonyanya kuoxidized, nepo boka re ester riri nyore ku hydrolyzed. Kurongeka kwe resistance yavo ye antioxidant uye hydrolysis ndekwekuti:
Basa reAntioxidant: esters>urea>carbamate>ether;
Kuramba kweHydrolysis: ester
Kuti pave nekukwanisa kusimbaradza kwepolyether polyurethane uye kuti polyester polyurethane isashande zvakanaka, zvinowedzerwawo, zvakaita sekuwedzera 1% phenolic antioxidant Irganox1010 kuPTMEG polyether elastomer. Simba rekusimba re elastomer iyi rinogona kuwedzerwa ka3-5 kana tichienzanisa nerisina ma antioxidants (mhedzisiro yebvunzo mushure mekukwegura pa1500C kwemaawa 168). Asi haisi yega antioxidant ine simba pa polyurethane elastomers, phenolic 1rganox 1010 neTopanOl051 chete (phenolic antioxidant, hindraised amine light stabilizer, benzotriazole complex) zvine mhedzisiro yakakosha, uye yekutanga ndiyo yakanakisa, pamwe nekuti phenolic antioxidants inoenderana zvakanaka ne elastomers. Zvisinei, nekuda kwebasa guru remapoka ephenolic hydroxyl mukugadzirisa mashandiro e phenolic antioxidants, kuitira kudzivirira kuita uye "kukundikana" kweboka iri re phenolic hydroxyl rine mapoka e isocyanate muhurongwa, chiyero che isocyanates ne polyols hachifanirwe kunge chakakura zvakanyanya, uye ma antioxidants anofanira kuwedzerwa kune prepolymers uye chain extenders. Kana zvikawedzerwa panguva yekugadzirwa kwe prepolymers, zvinokanganisa zvakanyanya kugadzikana.
Zvinowedzerwa zvinoshandiswa kudzivirira hydrolysis ye polyester polyurethane elastomers kunyanya ma carbodiimide compounds, ayo anosangana nema carboxylic acids anogadzirwa ne ester hydrolysis muma polyurethane elastomer molecules kuti agadzire acyl urea derivatives, zvichidzivirira hydrolysis yakawanda. Kuwedzera kwe carbodiimide pachikamu che 2% kusvika 5% kunogona kuwedzera kugadzikana kwemvura ye polyurethane ka2-4. Pamusoro pezvo, tert butyl catechol, hexamethylenetetramine, azodicarbonamide, nezvimwewo zvine zvimwe zvinodzivirira hydrolysis.
04 Hunhu hukuru hwekushanda
Polyurethane elastomers imhando yema multi block copolymers, ine ma molecular chains akaumbwa nezvikamu zvinochinjika zvine tembiricha yekuchinja kwegirazi yakaderera pane tembiricha yemumba uye zvikamu zvakasimba zvine tembiricha yekuchinja kwegirazi yakakwira kupfuura tembiricha yemumba. Pakati pawo, oligomeric polyols dzinoumba zvikamu zvinochinjika, nepo diisocyanates uye small molecule chain extenders dzichiumba zvikamu zvakasimba. Maumbirwo akabatanidzwa ezvikamu zve chain zvinochinjika uye zvakasimba anosarudza mashandiro azvo akasiyana:
(1) Hunhu hwekuoma kwerabha yakajairika hunowanzova pakati peShaoer A20-A90, nepo hunhu hwekuoma kwepurasitiki hunenge Shaoer A95 Shaoer D100. Polyurethane elastomers inogona kusvika pasi kusvika Shaoer A10 uye yakakwirira kusvika Shaoer D85, pasina rubatsiro rwekuzadza;
(2) Simba guru uye kutwasuka kunogona kuramba kuripo mukati mekuoma kwakasiyana-siyana;
(3) Kusapfeka zvakanaka, zvakapetwa kaviri kusvika gumi pane rabha yechisikigo;
(4) Kusabatwa zvakanaka nemvura, mafuta, uye makemikari;
(5) Kuramba kusimba zvakanyanya, kuramba kuneta, uye kuramba kudedera, zvakakodzera kushandiswa pakukotama kwakakwirira;
(6) Kudzivirira kupisa kwakaderera, nekuomarara kwekupisa kwakaderera pasi pe -30 ℃ kana -70 ℃;
(7) Ine simba rakanaka kwazvo rekudzivirira kupisa, uye nekuda kwekusapisa kwayo kwakaderera, ine simba riri nani rekudzivirira kupisa kana tichienzanisa nerabha nepurasitiki;
(8) Kushanda zvakanaka mumuviri uye hunhu hwekudzivirira ropa kubva muropa;
(9) Kudzivirira kwemagetsi kwakanaka, kudzivirira chakuvhuvhu, uye kugadzikana kweUV.
Ma elastomer epolyurethane anogona kugadzirwa achishandisa maitiro akafanana nerabha yakajairika, akadai se plasticization, mixing, uye vulcanization. Anogonawo kuumbwa muchimiro cherabha yemvura nekudira, centrifugal molding, kana kupfapfaidza. Anogonawo kugadzirwa kuita zvinhu zvakapwanyika uye kugadzirwa uchishandisa injection, extrusion, rolling, blow molding, nedzimwe nzira. Nenzira iyi, haingobatsiri chete kushanda zvakanaka, asi inovandudzawo kurongeka kwehukuru uye chitarisiko chechigadzirwa.
Nguva yekutumira: Zvita-05-2023