Kodi hydroxyethyl cellulose imapangidwa bwanji?

Hydroxyethyl Cellulose (HEC) ndi polima wamba wosungunuka m'madzi womwe umagwiritsidwa ntchito kwambiri pamankhwala atsiku ndi tsiku, zomangamanga, zokutira, mankhwala, chakudya ndi mafakitale ena. Ndi ether yosakhala ionic cellulose yopangidwa ndi kusintha kwa cellulose yachilengedwe. Njira yopangira hydroxyethyl cellulose imaphatikizapo machitidwe ovuta a mankhwala, kuphatikizapo ma cellulose m'zigawo, mankhwala a alkalization, etherification reaction, ndi zina zotero.

1. Kusankhidwa kwa zipangizo ndi kuchotsa mapadi
Zopangira zoyambira za hydroxyethyl cellulose ndi mapadi achilengedwe, omwe makamaka amachokera kumitengo, thonje kapena ulusi wina wazomera. Ma cellulose omwe ali m'makoma a cellulose ndiambiri, ndipo mapadi oyera amatha kuchotsedwa kuzinthu zachilengedwezi pogwiritsa ntchito makina kapena mankhwala. Njira yochotsera imaphatikizapo kuphwanya, kuchotsa zonyansa (monga lignin, hemicellulose), bleaching ndi njira zina.

Ma cellulose m'zigawo: Ma cellulose achilengedwe nthawi zambiri amapangidwa ndi makina kapena mankhwala kuti achotse zinthu zopanda cellulose kuti apeze cellulose yoyera kwambiri. Ulusi wa thonje, zamkati zamatabwa, ndi zina zonse zitha kukhala magwero azinthu zopangira. Pa chithandizo chamankhwala, alkali (monga sodium hydroxide) amagwiritsidwa ntchito pothandizira kusungunula zinthu zopanda cellulose, ndipo zotsalazo zimakhala makamaka mapadi.
2. Alkalization mankhwala
Ma cellulose oyeretsedwa ayenera choyamba kukhala alkali. Gawo ili ndikupanga magulu a hydroxyl pa cellulose cell chain kuti athe kuchitapo kanthu mosavuta ndi etherifying agent. Njira zazikulu za chithandizo cha alkalization ndi izi:

Zomwe zimachitika pa cellulose ndi alkali: mapadi amasakanikirana ndi alkali wamphamvu (nthawi zambiri sodium hydroxide) kupanga alkali cellulose (Alkali Cellulose). Izi kawirikawiri ikuchitika mu amadzimadzi sing'anga. Alkali cellulose ndi zomwe zimachitika pa cellulose ndi sodium hydroxide. Izi zimakhala ndi mawonekedwe otayirira komanso kuchitapo kanthu kwapamwamba, komwe kumathandizira kuti etherification ichitike.
Njira ya alkalization imachitika pa kutentha koyenera ndi chinyezi, nthawi zambiri mu 20 ℃ ~ 30 ℃ kwa maola angapo kuonetsetsa kuti magulu a hydroxyl mu mamolekyu a cellulose atsegulidwa kwathunthu.

3. Etherification reaction
Etherification ndi sitepe yofunika kwambiri pakupanga hydroxyethyl cellulose. Ma cellulose a Hydroxyethyl amapangidwa ndikuchitapo kanthu pa cellulose ya alkali ndi ethylene oxide kuyambitsa magulu a hydroxyethyl. Masitepe enieni ndi awa:

Zomwe zimachitika ndi ethylene oxide: Alkali cellulose imakhudzidwa ndi kuchuluka kwa ethylene oxide pansi pa kutentha ndi kupanikizika kwina. Mapangidwe a mphete mu ethylene oxide amatseguka kuti apange chomangira cha ether, amakumana ndi magulu a hydroxyl mu mamolekyu a cellulose, ndikuyambitsa magulu a hydroxyethyl (-CH2CH2OH). Njirayi imatha kusintha kuchuluka kwa etherification ndikuwongolera zomwe zimachitika (monga kutentha, kuthamanga, ndi nthawi).
Zomwe zimachitika nthawi zambiri zimachitika m'malo amchere kuti zitsimikizire kuti etherification imagwira ntchito bwino. The kutentha anachita zambiri 50 ℃ ~ 100 ℃, ndipo anachita nthawi ndi maola angapo. Ndi kusintha kuchuluka kwa ethylene okusayidi, mlingo wa m'malo chomaliza mankhwala akhoza kulamulidwa, ndiko kuti, angati magulu hydroxyl mu mapadi mamolekyu m'malo ndi magulu hydroxyethyl.

4. Kusalowerera ndale ndi kutsuka
Pambuyo etherification anachita anamaliza, ndi zamchere zinthu mu anachita dongosolo ayenera neutralized. Ma neutralizers omwe amagwiritsidwa ntchito kwambiri ndi zinthu za acidic, monga acetic acid kapena hydrochloric acid. Njira ya neutralization imapangitsa kuti alkali ochulukirapo akhale mchere, zomwe sizingakhudze magwiridwe antchito.

Neutralization reaction: Chotsani chinthucho mu riyakitala ndikuwonjezera asidi woyenerera kuti asasokonezedwe mpaka phindu la pH mudongosolo lifike ku ndale. Njirayi sikuti imachotsa zotsalira zamchere, komanso imachepetsanso zomwe zimachitika pakupanga kwa hydroxyethyl cellulose.

Kuchapira ndi kutaya madzi m'thupi: Chotsaliracho chiyenera kutsukidwa kangapo, nthawi zambiri ndi madzi kapena ethanol ndi zosungunulira zina kuti zichotse zotsalira zotsalira ndi zowonjezera. Chotsukidwacho chimatsitsidwa ndi centrifugation, kukanikiza zosefera ndi njira zina zochepetsera chinyezi.

5. Kuyanika ndi kuphwanya
Pambuyo kutsuka ndi kutaya madzi m'thupi, hydroxyethyl cellulose imakhalabe ndi madzi enaake ndipo imayenera kuumitsidwanso. Njira yowumitsa imatha kuchitidwa ndi kuyanika kwa mpweya kapena kuunika kwa vacuum kuti zitsimikizire kuti mankhwalawa ali ndi bata labwino panthawi yosungira ndikugwiritsa ntchito.

Kuyanika: Yanikani chinthucho pa kutentha kwina (nthawi zambiri pansi pa 60 ° C) kuchotsa chinyezi chotsalira. Kutentha kowumitsa sikuyenera kukhala kokwera kwambiri, mwinamwake kungayambitse kuwonongeka kwa mankhwala ndikukhudza ntchito yake.

Kuphwanya ndi kuwunika: Ma cellulose owuma a hydroxyethyl amakhala mu midadada kapena zotupa, ndipo amayenera kuphwanyidwa kuti apeze ufa wabwino. Chophwanyidwacho chiyeneranso kuyang'anitsitsa kuti tipeze kugawa kwa tinthu komwe kumakwaniritsa zofunikira kuti zitsimikizire kusungunuka kwake ndi kufalikira kwake muzogwiritsira ntchito.

6. Kuyesa ndi kulongedza zinthu zomaliza
Pambuyo popanga, hydroxyethyl cellulose iyenera kuyesedwa kuti ikhale yabwino kuti zitsimikizire kuti zizindikiro zake zimakwaniritsa zofunikira. Zinthu zoyeserera nthawi zambiri zimakhala:

Kuyeza kwa viscosity: The viscosity ya hydroxyethyl cellulose itatha kusungunuka m'madzi ndi chizindikiro chofunika kwambiri, chomwe chimakhudza kugwiritsidwa ntchito kwake mu zokutira, zomangamanga, mankhwala a tsiku ndi tsiku ndi madera ena.
Chinyezi: Yesani chinyezi cha chinthucho kuti muwonetsetse kuti chisungidwe chake chili chokhazikika.
Degree of substitution (DS) ndi molar substitution (MS): Dziwani kuchuluka kwa kusintha ndi kusintha kwa molar muzogulitsa kudzera mu kusanthula kwamankhwala kuti zitsimikizire zotsatira za etherification reaction.
Mukapambana mayesowo, hydroxyethyl cellulose imapakidwa kukhala ufa kapena zinthu za granular, nthawi zambiri m'matumba apulasitiki osapanga chinyezi kapena zikwama zamapepala kuti zisanyowe kapena kuipitsidwa.

Njira yopangira hydroxyethyl cellulose makamaka imaphatikizapo masitepe a cellulose m'zigawo, mankhwala alkalization, etherification reaction, neutralization ndi kutsuka, kuyanika ndi kuphwanya. Njira yonseyi imadalira alkalization ndi etherification muzochita zamakina, ndipo mapadi amapatsidwa kusungunuka kwamadzi bwino ndi kukhuthala kwazinthu poyambitsa magulu a hydroxyethyl. Hydroxyethyl mapadi chimagwiritsidwa ntchito m'mafakitale ambiri, monga thickener kwa zokutira, madzi kusunga wothandizila zomangira, stabilizer mu mankhwala tsiku ndi tsiku mankhwala, etc. Ulalo uliwonse mu ndondomeko kupanga ayenera mosamalitsa ankalamulira kuonetsetsa apamwamba ndi ntchito khola. za mankhwala.