1.Structure thiab npaj txoj cai ntawm cellulose ether
Daim duab 1 qhia txog cov qauv ntawm cellulose ethers. Txhua chav bD-anhydroglucose (chav rov ua dua ntawm cellulose) hloov ib pawg ntawm C (2), C (3) thiab C (6) txoj haujlwm, uas yog, tuaj yeem muaj txog peb pawg ether. Vim lub intra-chain thiab inter-chain hydrogen bonds ntawmcellulose macromolecules, nws yog ib qho nyuaj rau yaj nyob rau hauv dej thiab yuav luag tag nrho cov organic solvents. Kev taw qhia ntawm ether pawg los ntawm etherification rhuav tshem intramolecular thiab intermolecular hydrogen bonds, txhim kho nws cov hydrophilicity, thiab zoo heev txhim kho nws solubility hauv dej xov xwm.
Cov etherified hloov pauv tsis tshua muaj molecular hnyav alkoxy pawg (1 txog 4 carbon atoms) los yog hydroxyalkyl pawg, uas tej zaum yuav raug hloov los ntawm lwm pab pawg xws li carboxyl, hydroxyl lossis amino pawg. Cov neeg hloov pauv tuaj yeem yog ib, ob lossis ntau hom sib txawv. Raws li cov cellulose macromolecular saw, pawg hydroxyl ntawm C (2), C (3) thiab C (6) txoj haujlwm ntawm txhua chav tsev qabzib tau hloov pauv hauv qhov sib txawv. Hais lus nruj me ntsis, cellulose ether feem ntau tsis muaj cov qauv tshuaj lom neeg, tshwj tsis yog rau cov khoom lag luam uas tau hloov tag nrho los ntawm ib pab pawg (tag nrho peb pawg hydroxyl hloov). Cov khoom no tsuas yog siv rau kev kuaj xyuas thiab kev tshawb fawb, thiab tsis muaj nqi lag luam.
(a) Cov qauv dav dav ntawm ob chav anhydroglucose ntawm cellulose ether molecular saw, R1 ~ R6 = H, lossis cov organic hloov pauv;
(b) Cov saw hlau molecular ntawm carboxymethylhydroxyethyl cellulose, qib ntawm kev hloov pauv ntawm carboxymethyl yog 0.5, qib ntawm kev hloov ntawm hydroxyethyl yog 2.0, thiab qib ntawm kev hloov ntawm molar yog 3.0. Cov qauv no sawv cev rau qhov nruab nrab hloov pauv ntawm pawg etherified, tab sis cov neeg hloov pauv yog qhov tseeb.
Rau txhua qhov hloov pauv, tag nrho cov nyiaj ntawm etherification yog qhia los ntawm qib ntawm kev hloov pauv DS tus nqi. Qhov ntau ntawm DS yog 0 ~ 3, uas yog sib npaug rau qhov nruab nrab ntawm cov pawg hydroxyl hloov los ntawm etherification pawg ntawm txhua chav tsev anhydroglucose.
Rau hydroxyalkyl cellulose ethers, kev hloov pauv cov tshuaj tiv thaiv yuav pib etherification los ntawm cov pab pawg dawb hydroxyl tshiab, thiab qib ntawm kev hloov pauv tuaj yeem suav tau los ntawm MS tus nqi, uas yog, molar degree ntawm kev hloov pauv. Nws sawv cev rau qhov nruab nrab ntawm cov moles ntawm etherifying tus neeg sawv cev reactant ntxiv rau txhua chav tsev anhydroglucose. Ib tug raug reactant yog ethylene oxide thiab cov khoom muaj ib tug hydroxyethyl substituent. Hauv daim duab 1, MS tus nqi ntawm cov khoom yog 3.0.
Raws li txoj cai, tsis muaj kev txwv siab rau MS tus nqi. Yog tias tus nqi DS ntawm qhov kev hloov pauv ntawm txhua pab pawg suab thaj tau paub, qhov nruab nrab ntawm cov saw hlau ntev ntawm ether sab saw Qee cov tuam txhab kuj feem ntau siv cov feem ntau (wt%) ntawm ntau pawg etherification (xws li -OCH3 lossis -OC2H4OH) los sawv cev rau qib hloov pauv thiab qib siab tsis yog DS thiab MS qhov tseem ceeb. Qhov loj feem ntawm txhua pab pawg thiab nws tus nqi DS lossis MS tuaj yeem hloov pauv los ntawm kev suav yooj yim.
Feem ntau cov cellulose ethers yog dej-soluble polymers, thiab qee qhov kuj yog ib nrab soluble hauv cov kuab tshuaj organic. Cellulose ether muaj cov yam ntxwv ntawm kev ua haujlwm siab, tus nqi qis, ua haujlwm yooj yim, tsis muaj tshuaj lom thiab ntau yam, thiab qhov kev thov thiab daim ntawv thov teb tseem nthuav dav. Raws li tus neeg sawv cev pabcuam, cellulose ether muaj peev xwm siv tau zoo hauv ntau yam kev lag luam. tuaj yeem tau txais los ntawm MS / DS.
Cellulose ethers raug cais raws li cov qauv tshuaj ntawm cov khoom hloov mus rau hauv anionic, cationic thiab nonionic ethers. Nonionic ethers tuaj yeem muab faib ua dej-soluble thiab roj-soluble khoom.
Cov khoom uas tau raug industrialized tau teev nyob rau sab sauv ntawm Table 1. Qhov qis dua ntawm Table 1 teev qee cov pab pawg paub etherification, uas tseem tsis tau dhau los ua cov khoom lag luam tseem ceeb.
Cov ntawv luv luv ntawm cov khoom sib xyaw ether tuaj yeem raug hu ua raws li cov tsiaj ntawv xaj lossis qib ntawm DS (MS), piv txwv li, rau 2-hydroxyethyl methylcellulose, cov ntawv luv yog HEMC, thiab nws kuj tuaj yeem sau ua MHEC rau highlight qhov methyl substituent.
Cov pab pawg hydroxyl ntawm cellulose tsis yooj yim nkag tau los ntawm cov neeg ua haujlwm etherification, thiab cov txheej txheem etherification feem ntau yog ua raws li alkaline tej yam kev mob, feem ntau yog siv cov concentration ntawm NaOH aqueous tov. Cov cellulose yog thawj zaug tsim rau hauv o alkali cellulose nrog NaOH aqueous tov, thiab tom qab ntawd nkag mus rau etherification cov tshuaj tiv thaiv nrog etherification tus neeg sawv cev. Thaum lub sij hawm tsim khoom thiab kev npaj ntawm cov ethers sib xyaw, ntau hom etherification agents yuav tsum tau siv tib lub sij hawm, los yog etherification yuav tsum tau nqa tawm ib kauj ruam los ntawm kev pub mis tsis tu ncua (yog tias tsim nyog). Muaj plaub hom tshuaj tiv thaiv nyob rau hauv etherification ntawm cellulose, uas yog sau los ntawm cov tshuaj tiv thaiv mis (cellulosic yog hloov los ntawm Cell-OH) raws li nram no:
Qhov sib npaug (1) piav qhia txog Williamson etherification cov tshuaj tiv thaiv. RX yog inorganic acid ester, thiab X yog halogen Br, Cl los yog sulfuric acid ester. Chloride R-Cl feem ntau yog siv rau hauv kev lag luam, piv txwv li, methyl chloride, ethyl chloride los yog chloroacetic acid. Ib tug stoichiometric tus nqi ntawm lub hauv paus yog noj nyob rau hauv xws li tshwm sim. Lub industrialized cellulose ether khoom methyl cellulose, ethyl cellulose thiab carboxymethyl cellulose yog cov khoom ntawm Williamson etherification cov tshuaj tiv thaiv.
Cov tshuaj tiv thaiv kab mob (2) yog cov tshuaj tiv thaiv ntxiv ntawm lub hauv paus-catalyzed epoxides (xws li R = H, CH3, los yog C2H5) thiab pawg hydroxyl ntawm cellulose molecules yam tsis siv lub hauv paus. Cov tshuaj tiv thaiv no yuav txuas ntxiv mus ntxiv raws li cov pab pawg hydroxyl tshiab tau tsim thaum lub sijhawm cov tshuaj tiv thaiv, ua rau tsim cov oligoalkylethylene oxide sab chains: Ib qho tshuaj tiv thaiv zoo sib xws nrog 1-aziridine (aziridine) yuav tsim aminoethyl ether: Cell-O-CH2-CH2-NH2 . Cov khoom xws li hydroxyethyl cellulose, hydroxypropyl cellulose thiab hydroxybutyl cellulose yog tag nrho cov khoom ntawm base-catalyzed epoxidation.
Cov tshuaj tiv thaiv kab mob (3) yog cov tshuaj tiv thaiv ntawm Cell-OH thiab cov organic tebchaw uas muaj ob daim ntawv cog lus hauv alkaline nruab nrab, Y yog ib pawg electron rho tawm, xws li CN, CONH2, lossis SO3-Na +. Niaj hnub no hom tshuaj tiv thaiv yog tsis tshua muaj siv industrially.
Cov tshuaj tiv thaiv mis (4), etherification nrog diazoalkane tseem tsis tau muaj kev lag luam.
- Hom cellulose ethers
Cellulose ether tuaj yeem yog monoether lossis sib xyaw ether, thiab nws cov khoom sib txawv. Muaj cov pab pawg hydrophilic qis ntawm cov cellulose macromolecule, xws li cov pab pawg hydroxyethyl, uas tuaj yeem tso cov khoom lag luam nrog qee qhov dej solubility, thaum rau cov pab pawg hydrophobic, xws li methyl, ethyl, thiab lwm yam, tsuas yog hloov pauv qib siab tau. muab cov khoom lag luam ib qho dej solubility, thiab cov khoom uas tsis tshua muaj kev hloov pauv tsuas yog swells hauv dej lossis tuaj yeem yaj hauv dilute alkali. daws. Nrog rau kev tshawb fawb tob txog cov khoom ntawm cellulose ethers, cellulose ethers tshiab thiab lawv daim ntawv thov teb yuav raug tsim thiab tsim tawm, thiab lub zog tsav loj tshaj plaws yog qhov dav thiab tsis tu ncua ua lag luam daim ntawv thov.
Txoj cai dav dav ntawm kev cuam tshuam ntawm pawg hauv cov ethers sib xyaw ntawm cov khoom solubility yog:
1) Ua kom cov ntsiab lus ntawm hydrophobic pawg nyob rau hauv cov khoom kom nce hydrophobicity ntawm ether thiab txo cov gel point;
2) Ua kom cov ntsiab lus ntawm hydrophilic pawg (xws li pawg hydroxyethyl) kom nws cov ntsiab lus gel;
3) Cov pab pawg hydroxypropyl yog tshwj xeeb, thiab hydroxypropylation kom zoo tuaj yeem txo cov gel kub ntawm cov khoom, thiab cov gel kub ntawm cov khoom nruab nrab hydroxypropylated yuav nce ntxiv, tab sis qib siab ntawm kev hloov pauv yuav txo nws cov ntsiab lus gel; Qhov laj thawj yog vim qhov tshwj xeeb carbon saw ntev qauv ntawm pawg hydroxypropyl, qib qis hydroxypropylation, tsis muaj zog hydrogen bonds nyob rau hauv thiab nruab nrab ntawm cov molecules hauv cellulose macromolecule, thiab hydrophilic hydroxyl pawg ntawm ceg chains. Dej yog qhov tseem ceeb. Ntawm qhov tod tes, yog tias kev hloov pauv siab, yuav muaj polymerization ntawm pawg sab nraud, cov ntsiab lus txheeb ze ntawm pawg hydroxyl yuav txo qis, hydrophobicity yuav nce, thiab solubility yuav txo qis.
Kev tsim khoom thiab kev tshawb fawb ntawmcellulose ethermuaj keeb kwm ntev. Xyoo 1905, Suida thawj zaug tau tshaj tawm txog etherification ntawm cellulose, uas yog methylated nrog dimethyl sulfate. Noionic alkyl ethers tau patented los ntawm Lilienfeld (1912), Dreyfus (1914) thiab Leuchs (1920) rau dej-soluble los yog roj-soluble cellulose ethers, feem. Buchler thiab Gomberg tsim benzyl cellulose nyob rau hauv 1921, carboxymethyl cellulose yog thawj zaug tsim los ntawm Jansen nyob rau hauv 1918, thiab Hubert tsim hydroxyethyl cellulose nyob rau hauv 1920. Nyob rau hauv thaum ntxov 1920s, carboxymethylcellulose tau ua lag luam nyob rau hauv lub teb chaws Yelemees. Los ntawm 1937 txog 1938, kev tsim khoom ntawm MC thiab HEC tau pom nyob hauv Tebchaws Meskas. Sweden tau pib tsim cov dej-soluble EHEC hauv xyoo 1945. Tom qab xyoo 1945, kev tsim cov cellulose ether nthuav dav hauv Western Europe, Tebchaws Meskas thiab Nyij Pooj. Thaum kawg ntawm xyoo 1957, Tuam Tshoj CMC tau tsim thawj zaug hauv Shanghai Celluloid Hoobkas. Los ntawm 2004, kuv lub teb chaws lub peev xwm ntau lawm yuav yog 30,000 tons ntawm ionic ether thiab 10,000 tons ntawm non-ionic ether. Los ntawm 2007, nws yuav ncav cuag 100,000 tons ntawm ionic ether thiab 40,000 tons ntawm Nonionic ether. Cov tuam txhab thev naus laus zis sib koom ua ke hauv tsev thiab txawv teb chaws kuj tau tshwm sim tas li, thiab Tuam Tshoj cov cellulose ether muaj peev xwm tsim tau thiab qib kev txhim kho tas li.
Nyob rau hauv xyoo tas los no, ntau cov cellulose monoethers thiab sib xyaw ethers nrog cov txiaj ntsig DS sib txawv, viscosities, purity thiab rheological zog tau tsim tas li. Tam sim no, lub hom phiaj ntawm txoj kev loj hlob nyob rau hauv lub teb ntawm cellulose ethers yog yuav tsum tau txais kev siv technology siab heev, tshiab kev npaj technology, tshiab khoom, tshiab cov khoom, high-zoo cov khoom, thiab systematic khoom yuav tsum tau technically tshawb fawb.
Lub sij hawm xa tuaj: Plaub Hlis-28-2024