Hydroxyethyl methyl cellulose (HEMC) ndi non-ionic cellulose ether kwambiri ntchito yomanga, zokutira, zoumba, mankhwala, chakudya ndi mafakitale ena. HEMC ili ndi madzi abwino osungunuka, kukhuthala, kusunga madzi, kupanga mafilimu ndi kugwirizanitsa katundu, ndipo imagwira ntchito yofunika kwambiri mumatope osakaniza owuma, utoto wa latex, detergent ndi zina.
1. Njira yopangira
1.1 Kukonzekera zakuthupi
HEMC imapangidwa makamaka kuchokera ku cellulose yachilengedwe yachilengedwe, methyl chloride (CH₃Cl), ethylene oxide (C₂H₄O), sodium hydroxide (NaOH) ndi zina zopangira.
Ma cellulose: Zamkati zamatabwa kapena zamkati za thonje nthawi zambiri zimagwiritsidwa ntchito ngati zopangira zazikulu, zomwe zimafunikira kuyera kwambiri komanso zonyansa zochepa kuti zitsimikizire mtundu wazinthu.
Alkalizer (NaOH): amagwiritsidwa ntchito kuyambitsa mapadi ndikuwongolera zochita.
Etherifying agent (CH₃Cl ndi C₂H₄O): perekani magulu a methyl ndi hydroxyethyl motsatana, kuti cellulose ilowe m'malo, imathandizira kusungunuka kwamadzi komanso magwiridwe antchito.
Organic zosungunulira (monga isopropanol): ntchito kupasuka reactants, kulamulira zochita chilengedwe ndi kuchepetsa mbali zochita.
1.2 Chithandizo cha alkalization
Pambuyo pakuphwanyidwa kwa cellulose, yankho loyenera la sodium hydroxide limawonjezeredwa ndipo chithandizo cha alkalization chimachitika pa kutentha kwina ndi kupanikizika, zomwe nthawi zambiri zimatenga mphindi 30-60. Cholinga chachikulu cha alkalization ndikukulitsa unyolo wa cellulose ndikuwongolera reactivity yake ndi etherifying agent. Izi kawirikawiri ikuchitika mu chatsekedwa riyakitala ndi oyambitsa kuonetsetsa kuti alkali njira wogawana likulowerera mu mapadi.
1.3 Etherification reaction
Ma cellulose a alkalized amakumana ndi methylation ndi hydroxyethylation reagents (CH₃Cl ndi C₂H₄O) mu riyakitala kupanga hydroxyethyl methyl cellulose. Zomwe mungachite ndi:
Kutentha: 60-90°C
Kuthamanga: 0.5-1.5 MPa
Nthawi: 2-5 hours
Zomwe zimachitika, methylation ndi hydroxyethylation reaction zimapitilira nthawi imodzi, kotero kuti gawo la hydroxyl (-OH) la cellulose lisinthidwa ndi methyl (-OCH).₃) ndi hydroxyethyl (-OCH₂CH₂OH), potero amasintha kusungunuka kwake ndi makulidwe ake. Kuti muwongolere kuchuluka kwa kusintha (ma DS ndi MS), nthawi zambiri pamafunika kukhathamiritsa dongosolo ndi gawo la etherification wothandizira.
1.4 Kusalowerera ndale ndi kutsuka
Zomwe zachitikazo zikamalizidwa, dongosololi likadali ndi alkali, zosungunulira komanso zopangira (monga NaCl). Chifukwa chake, neutralization ndi kutsuka ndikofunikira:
Neutralization: Gwiritsani ntchito asidi (monga acetic acid) kuti muchepetse alkali m'dongosolo ndikusintha pH kukhala 6-8.
Kusamba: Gwiritsani ntchito madzi ambiri otentha kapena ethanol amadzimadzi amadzimadzi kuti mutsuke mobwerezabwereza mapadi kuti muchotse zinthu zosakhudzidwa ndi zinthu zina, kuchepetsa zonyansa, ndikuwongolera chiyero cha mankhwalawa.
1.5 Kuyanika ndi kuphwanya
Pambuyo kutsuka, HEMC ikadali ndi chinyezi chambiri ndipo imayenera kuuma. Njira zowumitsa zodziwika bwino ndi izi:
Kuyanika kwa mpweya: kugwiritsa ntchito mpweya wotentha kwambiri kuti uume HEMC yonyowa, yogwira ntchito kwambiri komanso yoyenera kupanga zazikulu.
Kuyanika kwa vacuum: Kutenthetsa ndi kuyanika pansi pazambiri zotsika, zomwe zimatha kuteteza kuwonongeka kwa cellulose ndipo ndizoyenera pazinthu zapamwamba kwambiri.
Pambuyo kuyanika, HEMC imaphwanyidwa ndi pulverizer ndipo kukula kwa tinthu kumawongoleredwa ndikuwonetsetsa kuti mukwaniritse ubwino wofunikira wa mankhwala (nthawi zambiri 80-120 mesh).
2. Kuwongolera khalidwe
Kuwongolera khalidwe la HEMC kumaphatikizapo zizindikiro zotsatirazi:
Degree of substitution (DS ndi MS): imatsimikizira kusungunuka ndi kukhuthala, nthawi zambiri DS ili pakati pa 1.1-2.0 ndi MS ili pakati pa 0.1-0.5.
Chinyezi: nthawi zambiri chimafunika kukhala≤5%.
Viscosity: magiredi osiyanasiyana amakulidwe amafunikira pamagawo osiyanasiyana ogwiritsira ntchito (monga 400-100,000 mPa·s).
Kuyera: kumafuna phulusa lochepa, kuchotsa zosungunulira zotsalira, ndikuwonetsetsa kuti palibe fungo.
3. Magawo akuluakulu ogwiritsira ntchito
Zipangizo zomangira: zomwe zimagwiritsidwa ntchito mumatope a simenti, ufa wa putty, zomatira matailosi, kupititsa patsogolo kusunga madzi komanso ntchito yomanga.
Makampani okutira: amagwiritsidwa ntchito mu utoto wa latex ndi utoto, kuti apereke rheology yabwino komanso ntchito yotsutsa-sagging.
Mankhwala ndi chakudya: monga thickener ndi emulsifier, mogwirizana ndi chakudya kalasi kapena pharmacopoeia miyezo.
TheMtengo HEMC kupanga kumaphatikizapo alkalization, etherification, neutralization, kutsuka, kuyanika ndi kuphwanya. Kukhathamiritsa magawo azinthu ndikuwongolera digirii yolowa m'malo ndi kuyera kwazinthu ndiye makiyi owongolera magwiridwe antchito a HEMC. Ndi zofunikira zowonjezera pachitetezo cha chilengedwe ndi kupanga zobiriwira, kupanga HEMC kudzapereka chidwi kwambiri pakusunga mphamvu ndi kuchepetsa utsi ndi kugwiritsa ntchito zosungunulira zobiriwira m'tsogolomu.
Nthawi yotumiza: May-08-2025