Hydroxyethyl cellulose (HEC) yog non-ionic, dej-soluble polymer muab los ntawm cellulose, ib tug natural polymer pom nyob rau hauv lub cell phab ntsa ntawm cov nroj tsuag. Nws yog dav siv nyob rau hauv ntau yam lag luam, xws li tshuaj, tshuaj pleev ib ce, pleev xim, thiab adhesives, vim nws zoo heev thickening, film-forming, thiab rheological zog. Kev npaj ntawm hydroxyethyl cellulose koom nrog etherification ntawm cellulose nrog ethylene oxide nyob rau hauv alkaline tej yam kev mob. Cov txheej txheem no tuaj yeem tawg ua ob peb kauj ruam tseem ceeb: cellulose purification, alkalization, etherification, neutralization, ntxuav, thiab ziab.
1. Cellulose Purification
Thawj kauj ruam hauv kev npaj ntawm hydroxyethyl cellulose yog kev ua kom huv ntawm cellulose, feem ntau yog los ntawm ntoo pulp lossis paj rwb linters. Raw cellulose muaj impurities xws li lignin, hemicellulose, thiab lwm yam extractives uas yuav tsum tau muab tshem tawm kom tau high-purity cellulose haum rau tshuaj hloov kho.
Cov kauj ruam muaj feem xyuam:
Mechanical Processing: Cov cellulose nyoos yog mechanically ua kom txo nws qhov loj me thiab ua kom nws cov cheeb tsam saum npoo, yooj yim rau kev kho tshuaj tom ntej.
Tshuaj Kho Mob: Cov cellulose tau kho nrog cov tshuaj xws li sodium hydroxide (NaOH) thiab sodium sulfite (Na2SO3) txhawm rau txhawm rau lignin thiab hemicellulose, tom qab ntawd ntxuav thiab tshuaj dawb kom tshem tawm cov khoom seem thiab tau txais cov dawb, fibrous cellulose.
2. Alkalization
Tom qab ntawd cov purified cellulose yog alkalized los qhib nws rau cov tshuaj tiv thaiv etherification. Qhov no suav nrog kev kho cov cellulose nrog cov tshuaj aqueous ntawm sodium hydroxide.
Teb:
Cellulose + NaOH → Alkali cellulose
Txheej txheem:
Cov cellulose raug tshem tawm hauv dej, thiab cov tshuaj sodium hydroxide ntxiv. Qhov concentration ntawm NaOH feem ntau yog li ntawm 10-30%, thiab cov tshuaj tiv thaiv yog nqa tawm ntawm qhov kub ntawm 20-40 ° C.
Qhov sib tov yog nplawm kom ntseeg tau tias muaj kev nqus ntawm alkali, ua rau tsim cov alkali cellulose. Qhov nruab nrab no yog ntau reactive rau ethylene oxide, ua kom yooj yim rau cov txheej txheem etherification.
3. Etherification
Cov kauj ruam tseem ceeb hauv kev npaj ntawm hydroxyethyl cellulose yog etherification ntawm alkali cellulose nrog ethylene oxide. Cov tshuaj tiv thaiv no qhia cov pab pawg hydroxyethyl (-CH2CH2OH) rau hauv cov pob txha cellulose, ua rau nws cov dej-soluble.
Teb:
Alkali cellulose + Ethylene oxide → Hydroxyethyl cellulose + NaOH
Txheej txheem:
Ethylene oxide yog ntxiv rau alkali cellulose, nyob rau hauv ib lub batch los yog tas mus li txheej txheem. Cov tshuaj tiv thaiv feem ntau yog ua nyob rau hauv lub autoclave los yog siab reactor.
Cov tshuaj tiv thaiv kab mob, suav nrog qhov kub (50-100 ° C) thiab siab (1-5 atm), ua tib zoo tswj xyuas kom pom kev hloov pauv ntawm pawg hydroxyethyl. Qhov degree ntawm kev hloov pauv (DS) thiab molar hloov pauv (MS) yog qhov tseem ceeb tsis zoo uas cuam tshuam cov khoom ntawm cov khoom kawg.
4. Neutralization
Tom qab cov tshuaj tiv thaiv etherification, qhov sib tov muaj hydroxyethyl cellulose thiab residual sodium hydroxide. Cov kauj ruam tom ntej yog neutralization, qhov twg ntau tshaj alkali neutralized siv cov kua qaub, feem ntau acetic acid (CH3COOH) los yog hydrochloric acid (HCl).
Cov tshuaj tiv thaiv: NaOH + HCl → NaCl + H2O
Txheej txheem:
Cov kua qaub yog maj mam ntxiv rau cov tshuaj tiv thaiv sib tov nyob rau hauv kev tswj xyuas kom tsis txhob muaj cua sov thiab tiv thaiv degradation ntawm hydroxyethyl cellulose.
Qhov sib xyaw nruab nrab yog tom qab ntawd raug hloov kho pH kom ntseeg tau tias nws nyob hauv qhov xav tau, feem ntau nyob ib puag ncig nruab nrab pH (6-8).
5. Ntxuav
Tom qab neutralization, cov khoom yuav tsum tau ntxuav kom tshem tawm cov ntsev thiab lwm yam khoom los ntawm cov khoom. Cov kauj ruam no yog qhov tseem ceeb heev kom tau txais cov ntshiab hydroxyethyl cellulose.
Txheej txheem:
Cov tshuaj tiv thaiv sib tov yog diluted nrog dej, thiab hydroxyethyl cellulose yog cais los ntawm kev pom los yog centrifugation.
Cov hydroxyethyl cellulose sib cais yog rov qab ntxuav nrog dej deionized kom tshem tawm cov ntsev seem thiab impurities. Cov txheej txheem ntxuav txuas ntxiv mus kom txog thaum cov dej ntxuav tau nce mus txog qhov ntsuas qhov ntsuas, qhia txog kev tshem tawm cov dej tsis huv.
6. Qhuav
Cov kauj ruam kawg hauv kev npaj ntawm hydroxyethyl cellulose yog ziab. Cov kauj ruam no tshem tawm cov dej ntau dhau, yielding qhuav, hmoov khoom tsim nyog rau ntau yam kev siv.
Txheej txheem:
Cov tshuaj ntxuav hydroxyethyl cellulose yog kis rau ntawm cov tais kom qhuav los yog xa tawm los ntawm qhov chaw kom qhuav. Qhov kub kom qhuav yog ua tib zoo tswj kom tsis txhob muaj thermal degradation, feem ntau yog li ntawm 50-80 ° C.
Tsis tas li ntawd, cov tshuaj tsuag kom qhuav tuaj yeem siv tau kom qhuav sai thiab ua tau zoo. Hauv cov tshuaj tsuag kom qhuav, cov tshuaj aqueous hydroxyethyl cellulose yog atomized rau hauv cov tee dej thiab ziab hauv cov cua kub, uas ua rau cov hmoov zoo.
Cov khoom qhuav yog ces milled mus rau qhov xav tau particle loj thiab ntim rau cia thiab faib.
Kev Tswj Xyuas Zoo thiab Kev Siv
Thoob plaws hauv cov txheej txheem kev npaj, kev tswj xyuas nruj nruj yog siv los xyuas kom meej qhov sib xws thiab zoo ntawm hydroxyethyl cellulose. Cov tsis tseem ceeb xws li viscosity, qib ntawm kev hloov pauv, cov ntsiab lus noo noo, thiab particle loj tau saib xyuas tas li.
Daim ntawv thov:
Pharmaceuticals: Siv los ua tus neeg sawv cev thickening, binder, thiab stabilizer nyob rau hauv formulations xws li ntsiav tshuaj, suspensions, thiab tshuaj pleev.
Tshuaj pleev ib ce: Muab viscosity thiab kev ntxhib los mos rau cov khoom xws li cream, lotions, thiab tshuaj zawv plaub hau.
Paints thiab Coatings: Ua raws li cov thickener thiab rheology hloov kho, txhim kho daim ntawv thov zog thiab ruaj khov ntawm cov xim.
Kev lag luam khoom noj khoom haus: Ua haujlwm ua cov thickener, stabilizer, thiab emulsifier hauv ntau yam khoom noj.
Kev npaj ntawm hydroxyethyl cellulose koom nrog cov txheej txheem ntawm cov txheej txheem tshuaj thiab cov txheej txheem kho kom zoo los hloov kho cellulose los qhia cov pab pawg hydroxyethyl. Txhua kauj ruam, los ntawm kev ua kom huv ntawm cellulose mus rau ziab, yog qhov tseem ceeb hauv kev txiav txim siab qhov zoo thiab kev ua haujlwm ntawm cov khoom kawg. Hydroxyethyl cellulose cov khoom siv ntau yam ua rau nws muaj txiaj ntsig zoo hauv ntau qhov kev lag luam, qhia txog qhov tseem ceeb ntawm kev tsim cov kev coj ua kom tau raws li cov cai ntawm ntau yam kev siv.
Post lub sij hawm: May-28-2024