Hydroxyethyl Cellulose (HEC) yog cov dej-soluble polymer dav siv nyob rau hauv cov tshuaj niaj hnub, kev tsim kho, txheej, tshuaj, zaub mov thiab lwm yam lag luam. Nws yog non-ionic cellulose ether ua los ntawm chemically modifying natural cellulose. Kev tsim cov txheej txheem ntawm hydroxyethyl cellulose cuam tshuam cov tshuaj lom neeg, nrog rau kev tshem tawm cov cellulose, kev kho alkalization, cov tshuaj tiv thaiv etherification, thiab lwm yam. Cov hauv qab no yog cov lus qhia ntxaws txog nws cov txheej txheem tsim khoom.
1. Kev xaiv cov khoom siv raw thiab kev rho tawm ntawm cellulose
Cov khoom siv tseem ceeb ntawm hydroxyethyl cellulose yog ntuj cellulose, uas feem ntau yog los ntawm ntoo, paj rwb lossis lwm cov nroj tsuag fibers. Cov ntsiab lus cellulose nyob rau hauv cov nroj tsuag cell phab ntsa yog siab, thiab ntshiab cellulose yuav muab rho tawm los ntawm tej yam ntuj tso cov ntaub ntawv los ntawm txhua yam los yog tshuaj txhais tau tias. Cov txheej txheem extraction muaj xws li crushing, tshem tawm impurities (xws li lignin, hemicellulose), bleaching thiab lwm cov kauj ruam.
Cellulose extraction: Natural cellulose feem ntau yog kho los yog tshuaj kho kom tshem tawm cov tshuaj tsis yog cellulose kom tau txais cov cellulose siab. Cov paj rwb fiber ntau, ntoo pulp, thiab lwm yam tuaj yeem yog cov khoom siv raw. Thaum lub sij hawm kev kho mob, alkali (xws li sodium hydroxide) yog siv los pab yaj cov khoom uas tsis yog-cellulose, thiab cov seem yog feem ntau cellulose.
2. Kev kho alkalization
Lub purified cellulose yuav tsum ua ntej yuav alkalized. Cov kauj ruam no yog ua kom cov hydroxyl pawg ntawm cov cellulose molecular saw muaj zog kom lawv tuaj yeem hnov mob yooj yim dua nrog tus neeg sawv cev etherifying. Cov kauj ruam tseem ceeb ntawm kev kho alkalization yog raws li hauv qab no:
Cov tshuaj tiv thaiv cellulose nrog alkali: cellulose yog tov nrog alkali muaj zog (feem ntau yog sodium hydroxide) los tsim alkali cellulose (Alkali Cellulose). Cov txheej txheem no feem ntau yog nqa tawm hauv qhov nruab nrab aqueous. Alkali cellulose yog cov tshuaj tiv thaiv ntawm cellulose thiab sodium hydroxide. Cov tshuaj no muaj cov qauv xoob thiab ntau dua reactivity, uas yog qhov zoo rau cov tshuaj tiv thaiv etherification tom qab.
Cov txheej txheem alkalization feem ntau tshwm sim ntawm qhov ntsuas kub thiab av noo, feem ntau nyob rau hauv thaj tsam ntawm 20 ℃ ~ 30 ℃ rau ob peb teev kom ntseeg tau tias cov pawg hydroxyl hauv cov cellulose molecules tau ua haujlwm tag nrho.
3. Cov tshuaj tiv thaiv Etherification
Etherification yog ib kauj ruam tseem ceeb hauv kev tsim cov hydroxyethyl cellulose. Hydroxyethyl cellulose yog tsim los ntawm reacting alkali cellulose nrog ethylene oxide los qhia hydroxyethyl pawg. Cov kauj ruam tshwj xeeb yog raws li nram no:
Cov tshuaj tiv thaiv nrog ethylene oxide: Alkali cellulose reacts nrog qee qhov nyiaj ntawm ethylene oxide nyob rau hauv qee qhov kub thiab txias. Lub nplhaib qauv hauv ethylene oxide qhib los tsim ib daim ntawv cog lus ether, reacts nrog hydroxyl pawg nyob rau hauv cellulose molecules, thiab qhia hydroxyethyl pawg (–CH2CH2OH). Cov txheej txheem no tuaj yeem kho qhov degree ntawm etherification los ntawm kev tswj cov tshuaj tiv thaiv kab mob (xws li kub, siab, thiab lub sijhawm).
Cov tshuaj tiv thaiv feem ntau yog ua nyob rau hauv ib puag ncig alkaline los xyuas kom meej qhov ua tau zoo ntawm etherification. Cov tshuaj tiv thaiv kub feem ntau yog 50 ℃ ~ 100 ℃, thiab lub sijhawm tshuaj tiv thaiv yog ob peb teev. Los ntawm kev kho tus nqi ntawm ethylene oxide, qhov kev hloov pauv ntawm cov khoom kawg tuaj yeem tswj tau, uas yog, muaj pes tsawg hydroxyl pawg hauv cellulose molecules hloov los ntawm hydroxyethyl pawg.
4. Neutralization thiab ntxuav
Tom qab cov tshuaj tiv thaiv etherification tiav, cov tshuaj alkaline nyob rau hauv cov tshuaj tiv thaiv yuav tsum tau neutralized. Feem ntau siv neutralizers yog cov tshuaj acidic, xws li acetic acid lossis hydrochloric acid. Cov txheej txheem neutralization yuav neutralize cov alkali ntau dhau rau hauv cov ntsev, uas yuav tsis cuam tshuam rau kev ua haujlwm ntawm cov khoom.
Cov tshuaj tiv thaiv neutralization: Nqa cov khoom tawm ntawm lub reactor thiab ntxiv cov kua qaub rau qhov nruab nrab kom txog thaum tus nqi pH hauv lub cev nce mus txog nruab nrab. Cov txheej txheem no tsis tsuas yog tshem tawm cov seem alkali, tab sis kuj txo qhov cuam tshuam ntawm cov tshuaj tiv thaiv los ntawm cov khoom ntawm kev ua haujlwm ntawm hydroxyethyl cellulose.
Ntxuav thiab lub cev qhuav dej: Cov khoom nruab nrab yuav tsum tau ntxuav ob peb zaug, feem ntau yog dej los yog ethanol thiab lwm cov kuab tshuaj los ntxuav tawm cov khoom seem thiab cov khoom siv. Cov khoom ntxuav yog lub cev qhuav dej los ntawm centrifugation, lim nias thiab lwm txoj hauv kev los txo cov dej noo.
5. Qhuav thiab crushing
Tom qab ntxuav thiab lub cev qhuav dej, hydroxyethyl cellulose tseem muaj qee qhov dej noo thiab xav tau kom qhuav ntxiv. Cov txheej txheem ziab tuaj yeem ua tau los ntawm huab cua kom qhuav lossis nqus kom qhuav kom ntseeg tau tias cov khoom muaj kev ruaj ntseg zoo thaum khaws cia thiab siv.
Qhuav: Qhuav cov khoom ntawm qhov kub thiab txias (feem ntau qis dua 60 ° C) kom tshem tawm cov dej seem. Lub ziab kub yuav tsum tsis txhob siab dhau, txwv tsis pub nws yuav ua rau cov khoom degradation thiab cuam tshuam rau nws cov kev ua tau zoo.
Crushing thiab tshuaj ntsuam: Cov qhuav hydroxyethyl cellulose feem ntau muaj nyob rau hauv blocks los yog lumps, thiab yuav tsum tau crushed kom tau zoo hmoov. Cov khoom crushed tseem yuav tsum tau kuaj xyuas kom tau txais cov khoom me me uas ua tau raws li qhov yuav tsum tau ua kom ntseeg tau tias nws cov solubility thiab dispersibility nyob rau hauv cov ntaub ntawv siv.
6. Kev sim thiab ntim cov khoom kawg
Tom qab kev tsim khoom, hydroxyethyl cellulose yuav tsum tau kuaj xyuas kom zoo los xyuas kom meej tias nws cov ntsuas kev ua tau raws li tus qauv yuav tsum tau ua. Cov khoom kuaj feem ntau muaj xws li:
Kev ntsuas viscosity: Lub viscosity ntawm hydroxyethyl cellulose tom qab dissolving hauv dej yog ib qho tseem ceeb zoo qhia, uas cuam tshuam rau nws siv nyob rau hauv coatings, kev tsim kho, tshuaj niaj hnub thiab lwm yam teb.
Cov ntsiab lus noo noo: Ntsuas cov dej noo ntawm cov khoom kom ntseeg tau tias nws ruaj khov.
Degree ntawm kev hloov pauv (DS) thiab molar hloov pauv (MS): Txiav txim siab qib ntawm kev hloov pauv thiab molar hloov pauv hauv cov khoom los ntawm kev tshuaj xyuas tshuaj los xyuas kom meej cov nyhuv ntawm cov tshuaj tiv thaiv etherification.
Tom qab dhau qhov kev sim, hydroxyethyl cellulose yuav muab ntim rau hauv cov hmoov los yog cov khoom siv granular, feem ntau hauv cov hnab yas uas muaj dej tsis muaj dej los yog cov hnab ntawv los tiv thaiv kom tsis txhob ntub dej los yog muaj kab mob.
Kev tsim cov txheej txheem ntawm hydroxyethyl cellulose feem ntau suav nrog cov kauj ruam ntawm kev tshem tawm cellulose, kho alkalization, etherification cov tshuaj tiv thaiv, neutralization thiab ntxuav, ziab thiab crushing. Tag nrho cov txheej txheem nyob ntawm alkalization thiab etherification hauv cov tshuaj tiv thaiv, thiab cellulose tau muab cov dej zoo solubility thiab thickening zog los ntawm kev qhia cov pab pawg hydroxyethyl. Hydroxyethyl cellulose yog dav siv nyob rau hauv ntau industries, xws li thickener rau coatings, dej-retaining tus neeg saib xyuas rau lub tsev cov ntaub ntawv, stabilizer nyob rau hauv txhua txhua hnub cov khoom siv tshuaj, thiab lwm yam. ntawm cov khoom.
Post lub sij hawm: Oct-25-2024