Dab tsi yog kev tsim khoom thiab kev siv ntawmpolyether polyols?
Polyether Polyols ntau lawm:
Hauv kev lag luam polyurethane, polyether polyols feem ntau yog siv rau polyurethane ua npuas ncauj yas, suav nrog polyoxypropylene polyols thiab polytetramethylene ether glycols.
1. Cov Khoom Siv Tseem Ceeb:
- Organic oxides thiab cyclic compounds xws li furans;
- Cov thawj coj;
- Catalysts.
Piv txwv ntawm cov organic oxides thiab cyclic compounds muaj xws li epichlorohydrin, epichloropropane, epoxy propane, tetrahydrofuran, thiab lwm yam.
Initiators yog cov tsis tshua muaj qhov hnyav molecular compounds uas muaj hydroxyl, amino, los yog ob pawg hydroxyl thiab amino pawg, xws li propylene glycol, glycerol, trimethylolpropane, ethylenediamine, pentaerythritol, xylitol, sucrose, bisphenol A, bisphenol S, tris(2-hydroxyethyl) isocyanurate, thiab methylenedianiline.
Catalysts muab faib ua anionic, cationic, thiab hlau complex hom. Feem ntau siv catalysts hauv kev lag luam polyurethane suav nrog alkali hlau hydroxides ua anionic catalysts thiab Lewis acids ua cationic catalysts. Potassium hydroxide feem ntau yog siv.
2. Synthesis:
- Pretreatment of Raw Materials: Initiators thiab catalysts feem ntau yog pre-mixed los ua alkoxide, uas yog ntxiv rau cov tshuaj tiv thaiv hlab ntsha tom qab nqus dej.
- Nplhaib-qhib Polymerization Reaction: Cov tshuaj tiv thaiv no yog exothermic thiab yuav tsum tau tshem tawm raws sij hawm ntawm cov tshuaj tiv thaiv tshav kub kom tiv thaiv oxidation cov tshuaj tiv thaiv. Qhuav nitrogen gas yog qhia ua ntej cov tshuaj tiv thaiv los tiv thaiv oxidation.
- Cov txheej txheem tom qab kho: Feem ntau suav nrog neutralization, adsorption, lub cev qhuav dej, pom, distillation, thiab lwm yam.
Hom Polyether Polyols:
1. Polyoxypropylene Glycol:
- Kuj hu ua polypropylene glycol (PPG).
- Npaj nyob rau hauv iav-lined los yog stainless hlau tshuaj tiv thaiv hlab ntsha.
- Cov khoom pib (1,2-propylene glycol lossis 1,2-diol) thiab catalyst (potassium hydroxide) sib tov yog ntxiv rau cov catalyst npaj nkoj, rhuab mus rau 80-100 degree , thiab cov kuab tshuaj nyob rau hauv lub catalyst raug tshem tawm nyob rau hauv lub nqus tsev vacuum los txhawb alcoholysis. Tom qab ntawd cov catalyst hloov mus rau cov tshuaj tiv thaiv cov hlab ntsha, rhuab mus rau 90-120 degree , thiab propylene oxide ntxiv los tuav lub siab ntawm 0.07-0.35 MPa. Nruam polymerization ntawm propylene oxide tshwm sim ntawm qhov kub thiab txias no kom txog thaum muaj qee qhov hnyav molecular. Tom qab cov residual propylene oxide yog evaporated, cov khoom sib xyaw polyether raug xa mus rau lub nkoj nruab nrab, nruab nrab nrog cov tshuaj acidic, thiab tom qab ntawd lim, ua kom zoo, thiab ruaj khov kom tau txais cov khoom.
2. Polytetramethylene Ether Glycol (PTMEG):
- Polymerized los ntawm tetrahydrofuran nyob rau hauv lub xub ntiag ntawm cationic catalyst.
- Cov txheej txheem ntau lawm: Tetrahydrofuran yog ntxiv rau cov tshuaj tiv thaiv hlab ntsha, txias kom qis dua -5 degree, thiab sulfonic acid catalyst yog ntxiv dropwise nyob rau hauv lub zog stirring. Tom qab ntxiv cov dej ntsuas, qhov ntsuas kub tau nce mus rau 70-90 degree, tsis muaj kev cuam tshuam tetrahydrofuran yog distilled, thiab tom qab teeb tsa, nruab nrab, pom, thiab lub tshuab nqus tsev, polytetramethylene ether glycol tau txais.
3. Tetrahydrofuran-Oxide Propylene Copolymer Glycol:
- Copolymerized los ntawm tetrahydrofuran thiab propylene oxide nyob rau hauv catalysis ntawm Lewis acids.
- Ua los ntawm neutralization, ntxuav dej, lub cev qhuav dej, thiab pom.
4. Tshwj xeeb Polyether Polyols:
- suav nrog polyether polyols reactive, nplaim-retardant polyether polyols, grafted polyether polyols, polytetramethylene glycols, thiab heterocyclic hloov polyether polyols.
Cia thiab Toxicity:
Polyether polyols ntim tuaj yeem ua los ntawm cov hlau, txhuas, polyethylene, lossis polypropylene. Cia kub yuav tsum tsis txhob siab tshaj 70 degree, thiab cov ntim tau pom zoo kom ntim nrog nitrogen gas kom tiv thaiv kom txhob ya raws thiab oxidation. Polyether polyols tsis raug raws li cov kev cai cia cov kua nplaum nplaum tab sis yuav tsum tau muab cia kom deb ntawm cov dej hauv av los yog cov dej saum npoo av vim lawv tsis yooj yim biodegradable.
Feem ntau nruab nrab polyether polyols muaj qhov tsis zoo toxicity thaum noj ntawm qhov ncauj lossis hauv kev sib cuag nrog daim tawv nqaij, qhov muag, lossis cov mucous membranes, yog li kev tiv thaiv tus kheej tsis tsim nyog thaum siv. Txawm li cas los xij, amine-based polyether polyols tuaj yeem ua rau tawv nqaij thiab qhov muag vim lawv cov alkalinity, yog li kev nyab xeeb tsom iav thiab hnab looj tes yuav tsum hnav thaum ua haujlwm.