Cov txheej txheem ntws ntawm hydroxypropyl methylcellulose

Hydroxypropyl methylcellulose (HPMC)yog ib qho cellulose derivative uas yaj tau hauv dej, siv dav hauv kev tsim kho, tshuaj pleev ib ce, khoom noj thiab tshuaj pleev ib ce. Nws cov txheej txheem tsim khoom yog qhov nyuaj heev thiab muaj ntau kauj ruam, feem ntau suav nrog kev yaj, kev sib xyaw, kev ntxuav, kev ziab thiab kev tsoo cellulose.

1. Kev npaj cov khoom siv raw

Kev tsim cov hydroxypropyl methylcellulose siv cov nroj tsuag xws li ntoo lossis paj rwb ua cov khoom siv raw. Ua ntej, cellulose yuav tsum tau rho tawm ntawm cov nroj tsuag. Cov cellulose uas tau rho tawm feem ntau yog degreased, bleached, thiab impurity-tshem tawm kom tau txais cov khoom siv cellulose ntshiab.

2. Kev yaj ntawm cellulose

Cellulose yaj tsis tau zoo hauv dej, yog li nws yuav tsum tau yaj los ntawm cov kuab tshuaj thaum lub sijhawm tsim khoom. Cov kuab tshuaj feem ntau yog sib xyaw ntawm ammonium chloride thiab dej, lossis sib xyaw ntawm ammonia thiab ethanol. Ua ntej, cov cellulose ntshiab raug sib xyaw nrog cov kuab tshuaj thiab kho ntawm qhov kub siab kom ntseeg tau tias cov cellulose tuaj yeem yaj tag.

3. Kev ua tshuaj methylation

Ib tug neeg sawv cev methylating (xws li methyl chloride lossis methyl chloride) raug ntxiv rau hauv cov cellulose yaj rau methylation reaction. Lub hom phiaj tseem ceeb ntawm qhov reaction no yog los qhia cov methyl pawg (–OCH₃) los ua methyl cellulose. Cov txheej txheem no feem ntau yuav tsum tau ua nyob rau hauv ib puag ncig alkaline, thiab kev tswj hwm qhov kub thiab lub sijhawm reaction muaj kev cuam tshuam tseem ceeb rau cov qauv molecular thiab kev ua tau zoo ntawm cov khoom kawg.

4. Cov tshuaj tiv thaiv Hydroxypropylation

Cov methylated cellulose ntxiv reacts nrog acrylates (xws li allyl chloride) los qhia cov hydroxypropyl pawg (–OCH₂CH₃). Cov tshuaj tiv thaiv no feem ntau yog ua nyob rau hauv cov kua alkaline, thiab kev tswj hwm ntawm qhov kub thiab lub sijhawm tiv thaiv txiav txim siab cov ntsiab lus hydroxypropyl ntawm cov khoom. Qib ntawm hydroxypropylation ncaj qha cuam tshuam rau solubility, viscosity thiab lwm yam khoom siv lub cev thiab tshuaj ntawm HPMC.

5. Kev ua kom tsis muaj zog thiab ntxuav

Tom qab ua tiav qhov kev sib xyaw ua ke, qee cov tshuaj alkaline lossis cov tshuaj reagents tsis tau ua haujlwm yuav tseem nyob hauv lub cev. Yog li ntawd, nws yog qhov tsim nyog los tshem tawm cov tshuaj alkaline ntau dhau los ntawm kev kho mob neutralization. Neutralization feem ntau yog ua nrog cov kua qaub (xws li acetic acid lossis hydrochloric acid), thiab cov ntsev neutral yuav tsim tom qab cov tshuaj acid-base. Tom qab ntawd, cov khoom tsis huv hauv cov tshuaj raug tshem tawm los ntawm ntau zaus ntxuav kom ntseeg tau tias cov khoom huv.

6. Kev qhuav thiab ziab

Cov tshuaj cellulose uas ntxuav lawm yuav tsum tau qhuav dej, thiab feem ntau siv cov evaporation lossis ultrafiltration los tshem tawm cov dej. Cov tshuaj cellulose uas qhuav dej muaj cov khoom qhuav ntau, thiab tom qab ntawd nkag mus rau hauv cov txheej txheem ziab. Txoj kev ziab tuaj yeem yog kev ziab tshuaj tsuag, ziab nqus tsev lossis ziab cua sov. Kev tswj qhov kub thaum lub sijhawm ziab yog qhov tseem ceeb heev. Qhov kub siab dhau yuav ua rau cov khoom puas tsuaj lossis poob nws cov kev ua tau zoo.

7. Kev tsoo thiab kev sib tsoo

Cov hydroxypropyl methylcellulose qhuav yog nyob rau hauv daim ntawv hmoov thiab yuav tsum tau crushed thiab sifted kom tswj tau cov khoom me me hauv ib qho ntau yam. Cov txheej txheem sieving tuaj yeem ua kom cov khoom sib xws thiab tshem tawm cov impurities nrog cov khoom loj dua.

8. Ntim thiab khaws cia

Cov hydroxypropyl methylcellulose uas tshwm sim tuaj yeem tsim tawm hauv ntau hom ntawv ntim khoom raws li cov neeg siv khoom xav tau, xws li hnab, thoob, thiab lwm yam. Ua tib zoo saib xyuas kom tsis txhob muaj dej noo thaum lub sijhawm ntim khoom kom tiv thaiv cov khoom kom tsis txhob nqus dej noo thiab cuam tshuam rau nws cov kev ua tau zoo. Cov khoom ntim yuav tsum khaws cia rau hauv qhov chaw qhuav thiab txias kom tsis txhob muaj qhov kub thiab txias.

9. Kev tswj xyuas zoo

Yuav tsum muaj kev tswj xyuas zoo nruj heev ntawm txhua qhov txuas hauv cov txheej txheem tsim khoom kom ntseeg tau tias cov khoom kawg ua tau raws li cov qauv. Cov khoom sim feem ntau suav nrog: solubility, viscosity, pH tus nqi, cov ntsiab lus tsis huv thiab cov ntsiab lus noo noo. Cov yam ntxwv ntawm cov khoom cuam tshuam ncaj qha rau nws cov nyhuv hauv ntau qhov chaw siv, yog li kev tswj xyuas zoo yog qhov txuas tseem ceeb hauv kev tsim cov hydroxypropyl methylcellulose.

Cov txheej txheem tsim khoom ntawmhydroxypropyl methylcelluloseMuaj ntau yam tshuaj lom neeg thiab cov kauj ruam kho lub cev, thiab muaj cov kev cai siab rau cov txheej txheem. Qhov kub ntawm cov tshuaj tiv thaiv, lub sijhawm, pH thiab lwm yam yuav tsum tau tswj hwm nruj me ntsis hauv kev tsim khoom kom tau txais cov khoom lag luam nrog kev ua tau zoo tshaj plaws. Nrog rau kev nce qib ntawm kev tshawb fawb thiab thev naus laus zis thiab kev txhim kho thev naus laus zis ntau lawm, cov txheej txheem tsim khoom ntawm HPMC tau txhim kho tas li, thiab thaj chaw thov ntawm cov khoom kuj nthuav dav.