Hydroxyethyl methyl cellulose (HEMC) ke ether e seng ionic cellulose e sebelisoang haholo kahong, ho roala, lirafshoa, meriana, lijo le liindasteri tse ling. HEMC e na le ho qhibiliha ha metsi hantle, ho teteaneng, ho boloka metsi, ho etsa lifilimi le thepa ea ho kopanya, 'me e phetha karolo ea bohlokoa ho seretse se omileng, pente ea latex, sesepa le masimo a mang.
1. Mokhoa oa tlhahiso
1.1 Tokiso ea thepa e tala
HEMC e hlophisitsoe haholo ka selulose ea semela sa tlhaho, methyl chloride (CH₃Cl), ethylene oxide (C₂H₄O), sodium hydroxide (NaOH) le lisebelisoa tse ling tse tala.
Cellulose: Makhasi a lehong kapa a k'hothone a atisa ho sebelisoa e le thepa e ka sehloohong e tala, e hlokang bohloeki bo phahameng le litšila tse fokolang ho netefatsa boleng ba sehlahisoa.
Alkalizer (NaOH): e sebelisetsoa ho kenya tšebetsong selulose le ho ntlafatsa ts'ebetso ea karabelo.
Etherifying agent (CH₃Cl le C₂H₄O): fana ka lihlopha tsa methyl le hydroxyethyl ka ho latellana, e le hore selulose e kene karabelong ea sebaka, e ntlafatsa ho qhibiliha ha metsi le thepa ea ts'ebetso.
Organic solvent (joalo ka isopropanol): e sebelisetsoa ho qhaqha li-reactants, ho laola tikoloho ea ho itšoara le ho fokotsa maikutlo a mahlakoreng.
1.2 Kalafo ea alkalization
Ka mor'a hore cellulose e pshatlehe, tekanyo e loketseng ea tharollo ea sodium hydroxide e kenngoa 'me phekolo ea alkalization e etsoa ka mocheso o itseng le khatello, eo hangata e nkang metsotso e 30-60. Morero o ka sehloohong oa alkalization ke ho holisa ketane ea limolek'hule tsa cellulose le ho ntlafatsa ts'ebetso ea eona le sesebelisoa sa etherifying. Ts'ebetso ena hangata e etsoa ka sehatsetsing se koetsoeng ka ho sisinyeha ho netefatsa hore tharollo ea alkali e kenella ka ho lekana ka har'a selulose.
1.3 Karabelo ea Etherification
Alkalized cellulose e sebetsana le methylation le hydroxyethylation reagents (CH₃Cl le C₂H₄O) ka har'a mochini o hlahisang hydroxyethyl methyl cellulose. Maemo a ho arabela a kenyelletsa:
Mocheso: 60-90°C
Khatello: 0.5-1.5 MPa
Nako: lihora tse 2-5
Nakong ea karabelo, methylation le hydroxyethylation reactions li tsoela pele ka nako e le 'ngoe, e le hore karolo ea hydroxyl (-OH) ea cellulose e nkeloe sebaka ke methyl (-OCH).₃) le hydroxyethyl (-OCH₂CH₂OH), ka hona e fetola boleng ba eona ba ho solubility le botenya. E le ho ntlafatsa tekanyo ea ho fetola (litekanyetso tsa DS le MS), hangata hoa hlokahala ho ntlafatsa tatellano le karolo ea kenyelletso ea etherification agent.
1.4 Ho se nke lehlakore le ho hlatsoa
Ka mor'a hore karabelo e phethoe, tsamaiso e ntse e e-na le alkali e sa sebetseng, solvent le by-products (joaloka NaCl). Ka hona, neutralization le ho hlatsoa lia hlokahala:
Neutralization: Sebelisa asiti (joaloka acetic acid) ho fokotsa alkali tsamaisong le ho fetola pH ea boleng ho 6-8.
Ho hlatsoa: Sebelisa metsi a chesang a mangata kapa tharollo ea metsi a ethanol ho hlatsoa selulose khafetsa ho tlosa lintho tse sa amaneng le lihlahisoa, ho fokotsa litšila, le ho ntlafatsa bohloeki ba sehlahisoa.
1.5 Ho omisa le ho silakanya
Kamora ho hlatsoa, HEMC e ntse e na le mongobo o phahameng mme e hloka ho omisoa. Mekhoa e tloaelehileng ea ho omisa ke:
Ho omisa moea: ho sebelisa moea o chesang ka lebelo le phahameng ho omisa HEMC e metsi, ka katleho e phahameng le e loketseng tlhahiso e kholo.
Vacuum drying: ho futhumatsa le ho omisa tlas'a tikoloho ea khatello e tlaase, e ka thibelang ho senyeha ha cellulose ka katleho 'me e loketse lihlahisoa tsa boleng bo phahameng.
Ka mor'a ho omisa, HEMC e sithabelitsoe ke pulverizer 'me boholo ba likaroloana bo laoloa ka ho hlahloba ho finyella botle bo hlokahalang ba sehlahisoa (hangata 80-120 mesh).
2. Taolo ea boleng
Taolo ea boleng ba HEMC haholo-holo e kenyelletsa matšoao a latelang:
Degree of substitution (DS le MS): e etsa qeto ea ho solubility le viscosity, ka kakaretso DS e pakeng tsa 1.1-2.0 le MS e pakeng tsa 0.1-0.5.
Mongobo: hangata ho hlokahala ho ba≤5%.
Viscosity: limaraka tse fapaneng tsa viscosity lia hlokahala bakeng sa masimo a fapaneng a kopo (joalo ka 400-100,000 mPa·s).
Ho hloeka: ho hloka molora o fokolang, ho tlosoa ha li-solvents tse setseng, le ho netefatsa hore ha ho monko o monate.
3. Libaka tsa kopo tse ka sehloohong
Lisebelisoa tsa kaho: tse sebelisoang ka seretse sa samente, phofo ea putty, sekhomaretsi sa lithaele, ho ntlafatsa ho boloka metsi le ts'ebetso ea kaho.
Indasteri ea ho roala: e sebelisoang ka pente ea latex le pente, ho fana ka ts'ebetso e ntle ea rheology le anti-sagging.
Meriana le lijo: joalo ka motenya le emulsifier, ho latela maemo a lijo kapa litekanyetso tsa pharmacopoeia.
TheHEMC mokhoa oa tlhahiso o kenyelletsa alkalization, etherification, neutralization, ho hlatsoa, ho omisa le ho senya. Ho ntlafatsa maemo a ts'ebetso le ho ntlafatsa degree ea substitution le bohloeki ba sehlahisoa ke linotlolo tsa ho ntlafatsa ts'ebetso ea HEMC. Ka litlhoko tse ntseng li eketseha tsa ts'ireletso ea tikoloho le tlhahiso e tala, tlhahiso ea HEMC e tla lebisa tlhokomelo e eketsehileng ho boloka matla le ho fokotsa mocheso le ho sebelisoa ha li-solvents tse tala nakong e tlang.
Nako ea poso: May-08-2025