Kawm txog Kev Tswj Xyuas Zoo ntawm Hydroxypropyl Methyl Cellulose

Raws li qhov xwm txheej tam sim no ntawm HPMC kev tsim khoom hauv kuv lub tebchaws, cov yam ntxwv uas cuam tshuam rau qhov zoo ntawm hydroxypropyl methylcellulose raug tshuaj xyuas, thiab ntawm lub hauv paus no, yuav ua li cas txhawm rau txhim kho qib zoo ntawm hydroxypropyl methylcellulose tau tham thiab kawm, thiaj li mus rau hauv kev tsim khoom.

Lo lus tseem ceeb:hydroxypropyl methylcellulose; zoo; tswj; kev tshawb fawb

Hydroxypropyl methylcellulose (HPMC) yog non-ionic dej-soluble cellulose tov ether ua los ntawm paj rwb, ntoo, thiab etherified nrog propylene oxide thiab methyl chloride tom qab alkali o. Cellulose sib xyaw ether yog qhov hloov pauv ntawm ib qho kev hloov pauv ether muaj cov khoom tshwj xeeb zoo dua li cov qub monoether, thiab tuaj yeem ua si qhov kev ua tau zoo ntawm cellulose ether ntau dua thiab zoo kawg nkaus. Ntawm ntau cov ethers sib xyaw, hydroxypropyl methylcellulose yog qhov tseem ceeb tshaj plaws. Txoj kev npaj yog ntxiv propylene oxide rau alkaline cellulose. Muaj HPMC tuaj yeem piav qhia raws li cov khoom lag luam thoob ntiaj teb. Qhov degree ntawm kev hloov ntawm methyl pawg (DS tus nqi) yog 1.3 txog 2.2, thiab molar hloov qib ntawm hydroxypropyl yog 0.1 txog 0.8. Nws tuaj yeem pom los ntawm cov ntaub ntawv saum toj no tias cov ntsiab lus thiab cov khoom ntawm methyl thiab hydroxypropyl hauv HPMC yog qhov sib txawv, uas ua rau cov khoom kawg viscosity thiab qhov sib txawv ntawm qhov sib txawv ua rau muaj kev hloov pauv hauv qhov zoo ntawm cov khoom tiav ntawm ntau lub tuam txhab tsim khoom.

Hydroxypropyl methylcellulose tsim ether derivatives los ntawm tshuaj lom neeg cov tshuaj tiv thaiv, uas muaj ntau yam kev hloov nyob rau hauv nws muaj pes tsawg leeg, qauv thiab cov khoom, tshwj xeeb tshaj yog cov solubility ntawm cellulose, uas muaj peev xwm sib txawv raws li hom thiab tus nqi ntawm alkyl pawg qhia. Tau txais ether derivatives soluble nyob rau hauv dej, dilute alkali tov, polar solvents (xws li ethanol, propanol) thiab non-polar organic solvents (xws li benzene, ether), uas zoo heev nthuav ntau yam thiab daim ntawv thov teb ntawm cellulose derivatives.

1. Cov nyhuv ntawm hydroxypropyl methylcellulose alkalization txheej txheem ntawm kev ua tau zoo

Cov txheej txheem alkalization yog thawj kauj ruam hauv cov tshuaj tiv thaiv theem ntawm HPMC ntau lawm, thiab nws kuj yog ib qho ntawm cov kauj ruam tseem ceeb tshaj plaws. Qhov zoo ntawm HPMC cov khoom yog txiav txim siab los ntawm cov txheej txheem alkalization, tsis yog cov txheej txheem etherification, vim tias cov nyhuv alkalization ncaj qha cuam tshuam rau cov nyhuv ntawm etherification.

Hydroxypropyl methylcellulose cuam tshuam nrog alkaline tov los tsim alkali cellulose, uas yog heev reactive. Hauv cov tshuaj tiv thaiv etherification, cov tshuaj tiv thaiv tseem ceeb ntawm tus neeg sawv cev etherification rau qhov o, nkag mus, thiab etherification ntawm cellulose thiab tus nqi ntawm cov tshuaj tiv thaiv sab, qhov sib xws ntawm cov tshuaj tiv thaiv thiab cov khoom ntawm cov khoom kawg yog txhua yam cuam tshuam rau kev tsim thiab muaj pes tsawg leeg. alkali cellulose, yog li cov qauv thiab cov khoom siv tshuaj lom neeg ntawm alkali cellulose yog cov khoom tshawb fawb tseem ceeb hauv kev tsim cov cellulose ether.

2. Cov nyhuv kub ntawm qhov zoo ntawm hydroxypropyl methylcellulose

Nyob rau hauv ib tug tej yam concentration ntawm KOH aqueous tov, tus nqi adsorption thiab o degree ntawm hydroxypropyl methylcellulose rau alkali nce nrog qhov txo ntawm cov tshuaj tiv thaiv kub. Piv txwv li, cov zis ntawm alkali cellulose sib txawv nrog cov concentration ntawm KOH: 15%, 8% ntawm 10°C, thiab 4.2% ntawm 5°C. Cov txheej txheem ntawm cov qauv no yog qhov tsim ntawm alkali cellulose yog cov txheej txheem exothermic. Raws li qhov kub thiab txias, qhov adsorption ntawm hydroxypropyl methylcellulose ntawm alkali tus nqi yog txo, tab sis hydrolysis cov tshuaj tiv thaiv ntawm alkali cellulose yog loj heev, uas yog tsis conducive rau tsim ntawm alkali cellulose. Nws tuaj yeem pom los ntawm cov saum toj no uas txo qis alkalization kub yog qhov tsim nyog rau tiam ntawm alkali cellulose thiab inhibits cov tshuaj tiv thaiv hydrolysis.

3. Cov nyhuv ntawm additives rau qhov zoo ntawm hydroxypropyl methylcellulose

Hauv cellulose-KOH-dej system, cov tshuaj ntxiv—ntsev muaj txiaj ntsig zoo rau kev tsim cov alkali cellulose. Thaum cov concentration ntawm KOH cov tshuaj yog qis dua 13%, qhov adsorption ntawm cellulose rau alkali tsis cuam tshuam los ntawm kev ntxiv ntawm potassium chloride ntsev. Thaum cov concentration ntawm cov tshuaj lye yog siab dua 13%, tom qab ntxiv cov poov tshuaj chloride, qhov pom tseeb adsorption ntawm cellulose rau alkali Adsorption nce nrog cov concentration ntawm poov tshuaj chloride, tab sis tag nrho cov adsorption muaj peev xwm txo, thiab cov dej adsorption tsub kom ntau, yog li ntawd lub adsorption ntawm poov tshuaj chloride yog siab. Ntxiv ntsev yog feem ntau tsis zoo rau alkalization thiab o ntawm cellulose, tab sis ntsev tuaj yeem inhibit hydrolysis thiab tswj lub cev Cov dej dawb cov ntsiab lus yog li txhim kho cov nyhuv ntawm alkalization thiab etherification.

4. Kev cuam tshuam ntawm cov txheej txheem ntau lawm ntawm qhov zoo ntawm hydroxypropyl methylcellulose

Tam sim no, hydroxypropyl methylcellulose ntau lawm cov tuam txhab hauv kuv lub teb chaws feem ntau txais yuav cov txheej txheem ntau lawm ntawm cov kuab tshuaj. Kev npaj thiab etherification txheej txheem ntawm alkali cellulose yog tag nrho cov ua nyob rau hauv ib tug inert organic hnyav, yog li cov raw khoom refined paj rwb yuav tsum tau pulverized kom tau ib tug loj deg cheeb tsam thiab reactivity los xyuas kom meej qhov zoo ntawm cov khoom tiav.

Ntxiv cov pulverized cellulose, cov kuab tshuaj organic thiab alkali tov rau hauv lub reactor, thiab siv cov tshuab ua kom muaj zog ntawm qhov kub thiab txias thiab lub sijhawm kom tau txais alkali cellulose nrog cov alkalization zoo thiab tsawg degradation. Organic dilution cov kuab tshuaj (isopropanol, toluene, thiab lwm yam) muaj ib qho inertness, uas ua rau hydroxypropyl methylcellulose emit uniform kub thaum lub sij hawm tsim txheej txheem, qhia ib tug stepwise tso kev kawm, thaum txo cov hydrolysis cov tshuaj tiv thaiv ntawm alkali cellulose nyob rau hauv lub opposite kev taw qhia kom tau txais high- zoo alkali cellulose, feem ntau cov concentration ntawm lye siv nyob rau hauv no txuas yog siab li 50%.

Tom qab cellulose yog soaked nyob rau hauv lye, tag nrho o thiab tusyees alkalized alkali cellulose yog tau. Cov lye osmotically swells cellulose zoo dua, tso lub hauv paus zoo rau cov tshuaj tiv thaiv etherification tom ntej. Cov tshuaj diluents feem ntau suav nrog isopropanol, acetone, toluene, thiab lwm yam. Lub solubility ntawm lye, hom diluent thiab stirring tej yam kev mob yog lub ntsiab yam tseem ceeb cuam tshuam rau cov muaj pes tsawg leeg ntawm alkali cellulose. Cov txheej sab saud thiab qis yog tsim thaum sib tov. Cov txheej sab saud yog tsim los ntawm isopropanol thiab dej, thiab cov txheej txheem qis yog tsim los ntawm alkali thiab ib qho me me ntawm isopropanol. Cov cellulose dispersed nyob rau hauv lub system yog tag nrho nyob rau hauv kev sib cuag nrog lub sab sauv thiab sab cov kua txheej nyob rau hauv mechanical stirring. Cov alkali hauv qhov system Cov dej sib npaug hloov mus txog thaum cellulose tsim.

Raws li ib tug raug cellulose uas tsis yog-ionic tov ether, cov ntsiab lus ntawm hydroxypropyl methylcellulose pawg yog nyob rau txawv macromolecular chains, uas yog, qhov kev faib piv ntawm methyl thiab hydroxypropyl pawg yog sib txawv nyob rau hauv C ntawm txhua lub nplhaib qab zib txoj hauj lwm. Nws muaj ntau dua dispersion thiab randomness, ua rau nws nyuaj los lav qhov zoo stability ntawm cov khoom.