Focus on Cellulose ethers

Umahluko phakathi kwe-HPMC kunye ne-MC, HEC, CMC

I-Cellulose ikakhulu idlala iindima ezintathu zokuqina, ukugcinwa kwamanzi kunye nokwakhiwa kodaka kunye nepeyinti.

Ukutyebisa: Iselulosi inokujiya ukuze inqunyanyiswe kwaye igcine iyunifomu yesisombululo inyuka naphantsi, kwaye imelane nokudodobala.

Ukugcinwa kwamanzi: yenza udaka kunye nepeyinti yome kancinane, kwaye uncedise izinto ezifana nothuthu kunye nekhalsiyam ukuba zisebenze phantsi kwentshukumo yamanzi.

Ukwakhiwa: I-Cellulose inefuthe lokuthambisa, elinokwenza ii-mortars kunye neengubo zinezakhiwo ezilungileyo zokwakha.

1. I-Methyl cellulose (MC)

Emva kokuba umqhaphu osulungekisiweyo uphathwe ngealkali, i-cellulose ether iveliswa ngothotho lweempendulo ngemethane chloride njenge-etherification agent. Ngokubanzi, iqondo lokutshintsha liyi-1.6 ~ 2.0, kwaye ukunyibilika kwahluka ngokwamanqanaba okutshintsha. yeye-non-ionic cellulose ether.

(1) I-Methylcellulose iyanyibilika emanzini abandayo, kwaye kuya kuba nzima ukuyinyibilika emanzini ashushu. Isisombululo saso samanzi sizinzile kakhulu kuluhlu lwe-pH = 3 ~ 12. Inokuhambelana kakuhle nestatshi, i-guar gum, njl. kunye nee-surfactants ezininzi. Xa iqondo lokushisa lifikelela kwiqondo lokushisa, i-gelation iyenzeka.

(2) Ukugcinwa kwamanzi kwe-methyl cellulose kuxhomekeke kwisixa sokongeza, i-viscosity, i-particle fineness kunye nesantya sokuchithwa. Ngokuqhelekileyo, ukuba isixa esongezelelweyo sikhulu, i-fineness incinci, kwaye i-viscosity inkulu, izinga lokugcinwa kwamanzi liphezulu. Phakathi kwabo, inani lokongezelela linempembelelo enkulu kwizinga lokugcinwa kwamanzi, kwaye inqanaba le-viscosity alilingani ngokuthe ngqo kwinqanaba lokugcinwa kwamanzi. Izinga lokuchithwa ikakhulu lixhomekeke kwiqondo lokuguqulwa komphezulu we-cellulose particleness kunye ne-particle fineness. Phakathi kwezi zingentla ze-cellulose ethers, i-methyl cellulose kunye ne-hydroxypropyl methyl cellulose zinezinga eliphezulu lokugcina amanzi.

(3) Utshintsho kwiqondo lobushushu luya kuchaphazela kakhulu izinga lokugcinwa kwamanzi kwi-methyl cellulose. Ngokuqhelekileyo, okukhona ubushushu buphezulu, kokukhona ukugcinwa kwamanzi kubi. Ukuba ubushushu bomdaka budlula i-40 ° C, ukugcinwa kwamanzi kwe-methyl cellulose kuya kuncitshiswa kakhulu, kuchaphazela kakhulu ukwakhiwa kodaka.

(4) I-Methyl cellulose inefuthe elibonakalayo ekusebenzeni kunye nokunamathela komdaka. “Ukuncamathisela” apha kubhekisa kumandla okuncamathelisa okuvakala phakathi kwesixhobo sokufaka isicelo somsebenzi kunye nenxalenye yodonga, oko kukuthi, ukuxhathisa kokucheba kodaka. I-adhesiveness iphezulu, ukuxhathisa i-shear yodaka kukhulu, kwaye amandla afunwa ngabasebenzi kwinkqubo yokusetyenziswa nawo mkhulu, kwaye ukusebenza kokwakhiwa kodaka kubi. I-Methyl cellulose adhesion ikwinqanaba eliphakathi kwiimveliso ze-cellulose ether.

2. IHydroxypropylmethylcellulose (HPMC)

IHydroxypropyl methylcellulose luhlobo lweselulosi oluphuma kunye nokusetyenziswa kwayo kuye kwanda ngokukhawuleza kwiminyaka yakutshanje. I-ether engeyiyo ionic cellulose exutywe ne-ether eyenziwe kwi-cotton ecocekileyo emva kwe-alkalization, isebenzisa i-propylene oxide kunye ne-methyl chloride njenge-etherification agent, ngokusebenzisa uluhlu lweempendulo. Iqondo lokutshintshwa ngokubanzi yi-1.2 ~ 2.0. Iimpawu zayo zihluke ngenxa yemilinganiselo eyahlukeneyo yomxholo we-methoxyl kunye nomxholo we-hydroxypropyl.

(1) IHydroxypropyl methylcellulose inyibilika ngokulula emanzini abandayo, kwaye iya kudibana nobunzima ekunyibilikeni kumanzi ashushu. Kodwa ubushushu bayo be-gelation emanzini ashushu buphezulu kakhulu kune-methyl cellulose. Ukunyibilika kumanzi abandayo kuphuculwe kakhulu xa kuthelekiswa ne-methyl cellulose.

(2) I-viscosity ye-hydroxypropyl methylcellulose ihambelana nobunzima bayo be-molecular, kwaye ubukhulu be-molecular weight, buphezulu be-viscosity. Ubushushu buchaphazela i-viscosity yayo, njengoko izinga lokushisa linyuka, i-viscosity iyancipha. Nangona kunjalo, i-viscosity yayo ephezulu inefuthe eliphantsi lobushushu kune-methyl cellulose. Isisombululo sayo sizinzile xa sigcinwe kwiqondo lokushisa.

(3) Ukugcinwa kwamanzi kwe-hydroxypropyl methylcellulose kuxhomekeke kwisixa sokongeza, i-viscosity, njl.

(4) I-Hydroxypropyl methylcellulose izinzile kwi-asidi kunye ne-alkali, kwaye isisombululo sayo samanzi sizinzileyo kakhulu kwi-pH = 2 ~ 12. I-Caustic soda kunye namanzi e-lime anempembelelo encinci ekusebenzeni kwayo, kodwa i-alkali inokukhawulezisa ukuchithwa kwayo kunye nokwandisa i-viscosity yayo. I-Hydroxypropyl methylcellulose izinzile kwiityuwa eziqhelekileyo, kodwa xa ukuxinwa kwesisombululo setyuwa kuphezulu, i-viscosity ye-hydroxypropyl methylcellulose isisombululo ivame ukunyuka.

(5) I-Hydroxypropyl methylcellulose inokuxutywa kunye ne-polymer compounds e-soluble yamanzi ukuze yenze isisombululo esifanayo kunye ne-viscosity ephezulu. Okufana ne-polyvinyl alcohol, i-starch ether, i-gum yemifuno, njl.

(6) I-Hydroxypropyl methylcellulose inokumelana ne-enzyme engcono kune-methylcellulose, kunye nokuba kunokwenzeka ukuchithwa kwe-enzymatic yesisombululo sayo kuncinci kune-methylcellulose. Ukunamathela kwe-hydroxypropyl methylcellulose kulwakhiwo lodaka kuphezulu kune-methylcellulose.

3. I-Hydroxyethyl cellulose (HEC)

Yenziwe kwikotoni esulungekileyo ephathwe nge-alkali, kwaye iphendule nge-ethylene oxide njenge-etherification agent phambi kwe-acetone. Iqondo lokutshintshwa ngokubanzi yi-1.5 ~ 2.0. Ine-hydrophilicity eyomeleleyo kwaye kulula ukufunxa ukufuma.

(1) I-Hydroxyethyl cellulose iyanyibilika emanzini abandayo, kodwa kunzima ukuyinyibilika emanzini ashushu. Isisombululo saso sizinzile kwiqondo lokushisa eliphezulu ngaphandle kwe-gelling. Ingasetyenziselwa ixesha elide phantsi kobushushu obuphezulu kwidaka, kodwa ukugcinwa kwamanzi kwayo kuphantsi kune-methyl cellulose.

(2) I-Hydroxyethyl cellulose izinzile kwi-asidi ngokubanzi kunye ne-alkali. I-alkali inokukhawulezisa ukuchithwa kwayo kwaye inyuse kancinci i-viscosity yayo. I-dispersibility yayo emanzini imbi kancinane kune-methyl cellulose kunye ne-hydroxypropyl methyl cellulose. .

(3) I-Hydroxyethyl cellulose inokusebenza kakuhle kwe-anti-sag yodaka, kodwa inexesha elide lokubuyiswa kwesamente.

(4) Ukusebenza kwe-hydroxyethyl cellulose eveliswa ngamanye amashishini asekhaya iphantsi kakhulu kune-methyl cellulose ngenxa yobuninzi bamanzi kunye nomxholo ophezulu wothuthu.

4. I-Carboxymethyl cellulose (CMC)

I-Ionic cellulose ether yenziwe kwimicu yendalo (umqhaphu, njl.) Iqondo lokutshintshwa ngokubanzi yi-0.4 ~ 1.4, kwaye ukusebenza kwayo kuchatshazelwa kakhulu ngumgangatho wokutshintshwa.

(1) I-Carboxymethyl cellulose i-hygroscopic ngakumbi, kwaye iya kuba namanzi amaninzi xa igcinwe phantsi kweemeko eziqhelekileyo.

(2) I-Carboxymethyl cellulose isisombululo samanzi asivelisi i-gel, kwaye i-viscosity iyancipha ngokunyuka kweqondo lokushisa. Xa iqondo lokushisa lidlula i-50 ° C, i-viscosity ayinakuguqulwa.

(3) Ukuzinza kwayo kuchaphazeleka kakhulu yi-pH. Ngokuqhelekileyo, inokusetyenziswa kwi-gypsum-based mortar, kodwa kungekhona kwi-samente-based mortar. Xa i-alkaline iphezulu, ilahlekelwa yi-viscosity.

(4) Ugcino lwawo lwamanzi lungaphantsi kakhulu kunolo lwemethyl cellulose. Unempembelelo ephazamisayo kwi-gypsum-based mortar kwaye inciphisa amandla ayo. Nangona kunjalo, ixabiso le-carboxymethyl cellulose liphantsi kakhulu kunelo le-methyl cellulose

Indima ye-hydroxypropyl methylcellulose kwishishini lokugquma: Ngenxa yokuba i-HPMC ineepropati ezifanayo kwezinye ii-ethers ezinyibilikayo zamanzi, ingasetyenziselwa njenge-agent-forming agent, i-thickener, i-emulsifier kunye ne-stabilizer kwiipeyinti ze-emulsion kunye namalungu epeyinti ye-resin enyibilikayo yamanzi. i-arhente, njl., ukwenzela ukuba i-coating inokumelana nokunxiba kakuhle. Umgangatho kunye nokunamathela, kunye nokuphucula ukunyanzeliswa komphezulu, ukuzinza kwi-asidi kunye ne-alkali, kunye nokuhambelana kwee-pigments zetsimbi. Ngenxa yokuba i-gel point ye-HPMC iphezulu kune-MC, ukuchasana kwayo nokhukuliseko lwebhaktheriya kunamandla kunezinye ii-ethers ze-cellulose, ngoko inokusetyenziswa njenge-thickener yeepeyinti ze-emulsion yamanzi. I-HPMC inozinzo oluhle lokugcinwa kwe-viscosity, kwaye ine-dispersibility ebalaseleyo, ngoko ifanelekile ngokukodwa njenge-dispersant kwiingubo ze-emulsified.


Ixesha lokuposa: Mar-04-2023
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