Dab tsi yog qhov txawv ntawm polyester polyurethane thiab polyether polyurethane nyob rau hauv cov nqe lus ntawm cov tshuaj tiv thaiv txoj cai thiab cov tshuaj tiv thaiv tshwm sim?
1. Lub hauv paus ntsiab lus ntawm cov tshuaj tiv thaiv
Polyester polyurethane yog tau los ntawm cov tshuaj tiv thaiv ntawm polyester thiab isocyanate, nyob rau hauv polyester yog tau los ntawm polybasic acid (xws li adipic acid, phthalic acid, maleic acid, thiab lwm yam) thiab polyol (xws li ethylene glycol, propylene glycol, Trimethylolpropane, thiab lwm yam). Cov tshuaj tiv thaiv polycondensation, tuaj yeem muab faib ua ob hom hydroxyl polyester thiab carboxyl polyester, uas cov polyurethane ua npuas ncauj siv yog hydroxyl polyester, uas yog, ntau tshaj polyol.
Base polyester (ntau tshaj polyol): 2OH-R-OH ntxiv rau HOOC-R'-COOH — HO-R-OCO-R'-COO-R-OH
Carboxyl polyester (ntau tshaj polyacid): OH-R-OH ntxiv rau 2HOOC-R'-COOH—HOOC-R'-COO-R-OCO-R'-COOH
Polyether polyurethane yog tau los ntawm cov tshuaj tiv thaiv ntawm polyether polyol thiab isocyanate, nyob rau hauv polyether polyol yog tsim los ntawm cov nquag hydrogen-muaj cov pib (xws li cawv, amines) thiab olefin oxide (xws li ethylene oxide, propylene oxide) tau los ntawm lub nplhaib-qhib polymerization.
Polyether polyol: R-OH plus nPO-R-(-O-CH-CH3-CH2-}O)nH
Ob hom polyurethanes thaum kawg tsim los ntawm cov tshuaj tiv thaiv ntawm pawg hydroxyl nrog isocyanates los ua carbamates.
R-NCO plus R'-OH — RNHCOOR'
Yog li ntawd, nyob rau hauv cov nqe lus ntawm cov tshuaj tiv thaiv mechanism, qhov loj tshaj qhov sib txawv ntawm ob hom ntawm polyurethanes yog qhov txawv ntawm seb lub mos ntu molecular saw feem ntau muaj ib tug ester daim ntawv cog lus (-COO-) los yog ib tug ether daim ntawv cog lus (-COC-).
2. Cov tshuaj tiv thaiv
Polyester polyurethane muaj zog txhua yam, zoo roj kuj thiab kub tsis kam, yog li nws yog tsuas yog siv nyob rau hauv microcellular ua npuas ncauj soles, raws li zoo raws li elastomers, coatings thiab dag tawv.
Vim muaj cov ester bonds (unsaturated ob daim ntawv cog lus), kev ruaj ntseg ntawm polyester polyurethanes nyob rau hauv hydrolysis tsis kam, tsis kub tsis kam, oxidation kuj, acid kuj thiab alkali kuj tsis zoo li cov polyether polyurethanes.
3. txoj kev loj hlob
Vim lub siab viscosity ntawm polyester polyol nws tus kheej, tsis zoo miscibility nrog rau lwm yam Cheebtsam, nyuaj siv, thiab siab nqi ntawm raw cov ntaub ntawv, nws daim ntawv thov nyob rau hauv lub tshav pob ntawm polyurethane yog tsis ntau. Ntawm qhov tsis sib xws, daim ntawv thov ntawm polyether polyurethane yog dav heev. , tab sis feem ntau yog siv nyob rau hauv hluavtaws ua npuas ncauj.
Nyob rau hauv xyoo tas los no, txhawm rau txhim kho cov khoom siv thev naus laus zis ntawm polyester polyols, oxyalkylene tebchaw (xws li PO\EO) tau nkag mus rau hauv polyester polyol molecules, kom cov ntu mos molecular saw muaj ob qho ester bonds (-COO-) thiab ether bonds (-COO-) COC-), cov polyurethane tau los ntawm cov polyol tshiab no muaj cov yam ntxwv ntawm polyester thiab polyether polyurethane tib lub sijhawm.
