1.Tsarin da ka'idar shiri na cellulose ether
Hoto 1 yana nuna tsarin al'ada na ethers cellulose. Kowace bD-anhydroglucose naúrar (nau'in maimaitu na cellulose) yana maye gurbin rukuni ɗaya a matsayi C (2), C (3) da C (6), wato, za'a iya samun ƙungiyoyin ether guda uku. Sakamakon intra-chain da inter-chain hydrogen bond nacellulose macromolecules, yana da wuya a narke cikin ruwa da kusan dukkanin kaushi na kwayoyin halitta. Gabatarwar ƙungiyoyin ether ta hanyar etherification yana lalata haɗin gwiwar intramolecular da intermolecular hydrogen, yana inganta haɓakar ruwa, kuma yana inganta haɓakarsa sosai a cikin kafofin watsa labarai na ruwa.
Mahimman abubuwan maye gurbi sune ƙananan ƙwayoyin ƙwayoyin alkoxy (1 zuwa 4 carbon atoms) ko ƙungiyoyin hydroxyalky, waɗanda za a iya maye gurbinsu da wasu ƙungiyoyin aiki kamar carboxyl, hydroxyl ko amino ƙungiyoyi. Masu maye gurbin na iya zama nau'i ɗaya, biyu ko fiye daban-daban. Tare da sarkar macromolecular cellulose, ƙungiyoyin hydroxyl akan matsayi na C (2), C (3) da C (6) na kowane rukunin glucose ana maye gurbinsu da ma'auni daban-daban. Magana mai mahimmanci, ether cellulose gabaɗaya ba shi da takamaiman tsarin sinadarai, sai dai samfuran da aka maye gurbinsu gaba ɗaya da nau'in rukuni ɗaya (dukkan ƙungiyoyin hydroxyl guda uku an maye gurbinsu). Ana iya amfani da waɗannan samfuran kawai don nazarin dakin gwaje-gwaje da bincike, kuma ba su da darajar kasuwanci.
(a) Tsarin gabaɗaya na raka'o'in anhydroglucose guda biyu na sarkar kwayoyin ether cellulose, R1 ~ R6 = H, ko madaidaicin kwayoyin halitta;
(b) Guntun sarkar kwayoyin halitta na carboxymethylhydroxyethyl cellulose, Matsayin maye gurbin carboxymethyl shine 0.5, matakin maye gurbin hydroxyethyl shine 2.0, kuma matakin maye gurbin molar shine 3.0. Wannan tsarin yana wakiltar matsakaicin matakin maye gurbi na ƙungiyoyi masu ƙima, amma masu maye gurbin ainihin bazuwar.
Ga kowane madaidaici, jimlar adadin etherification ana bayyana shi ta matakin maye gurbin ƙimar DS. Matsakaicin DS shine 0 ~ 3, wanda yayi daidai da matsakaicin adadin ƙungiyoyin hydroxyl waɗanda aka maye gurbinsu da ƙungiyoyin etherification akan kowace rukunin anhydroglucose.
Ga hydroxyalkyl cellulose ethers, musanya dauki zai fara etherification daga sabon free hydroxyl kungiyoyin, da kuma matakin maye za a iya ƙididdige ta da MS darajar, wato, molar digiri na maye. Yana wakiltar matsakaicin adadin moles na etherifying wakili mai amsawa da aka ƙara zuwa kowace rukunin anhydroglucose. Mai amsawa na yau da kullun shine ethylene oxide kuma samfurin yana da madadin hydroxyethyl. A cikin Hoto 1, ƙimar MS na samfurin shine 3.0.
A ka'ida, babu babba iyaka ga ƙimar MS. Idan an san ƙimar DS na matakin maye gurbin akan kowane rukunin zoben glucose, matsakaicin matsakaicin tsayin sarkar gefen etherWasu masana'antun kuma galibi suna amfani da juzu'i mai yawa (wt%) na ƙungiyoyin etherification daban-daban (kamar -OCH3 ko -OC2H4OH) don wakiltar matakin maye gurbin da digiri maimakon ƙimar DS da MS. Yawan juzu'in kowace ƙungiya da ƙimar DS ko MS ɗin sa ana iya canzawa ta sauƙi mai sauƙi.
Yawancin ethers na cellulose sune polymers masu narkewa da ruwa, wasu kuma suna narkewa a cikin abubuwan kaushi. Cellulose ether yana da halaye na babban inganci, ƙarancin farashi, sauƙin sarrafawa, ƙarancin guba da iri-iri iri-iri, kuma buƙatu da filayen aikace-aikacen har yanzu suna faɗaɗa. A matsayin wakili na taimako, ether cellulose yana da babban damar aikace-aikacen a fannoni daban-daban na masana'antu. ana iya samun ta MS/DS.
An rarraba ethers na cellulose bisa ga tsarin sinadarai na masu maye gurbin zuwa anionic, cationic da nonionic ethers. Nonionic ethers za a iya raba zuwa ruwa-soluble kayayyakin da mai-mai narkewa.
Abubuwan da aka haɓaka masana'antu an jera su a cikin babban ɓangaren Teburin 1. Ƙananan ɓangaren Tebur 1 ya lissafa wasu sanannun ƙungiyoyin etherification, waɗanda har yanzu ba su zama samfuran kasuwanci masu mahimmanci ba.
Za'a iya ba da sunan gajarta na madaidaicin ether mai gauraye bisa ga tsarin haruffa ko matakin DS (MS), alal misali, don 2-hydroxyethyl methylcellulose, raguwar shine HEMC, kuma ana iya rubuta shi azaman MHEC zuwa haskaka madadin methyl.
Ƙungiyoyin hydroxyl akan cellulose ba su da sauƙi ta hanyar etherification jami'ai, kuma tsarin etherification yawanci ana aiwatar da shi a ƙarƙashin yanayin alkaline, gabaɗaya ta amfani da wani yanki na NaOH aqueous bayani. An fara samar da cellulose cikin alkali cellulose mai kumbura tare da maganin ruwa na NaOH, sa'an nan kuma ya sha maganin etherification tare da wakili na etherification. A lokacin samarwa da shirye-shiryen gauraye ethers, ya kamata a yi amfani da nau'ikan nau'ikan etherification daban-daban a lokaci guda, ko kuma a aiwatar da etherification mataki-mataki ta hanyar ciyarwa ta lokaci-lokaci (idan ya cancanta). Akwai nau'ikan amsawa guda huɗu a cikin etherification na cellulose, waɗanda aka taƙaita ta hanyar dabarar amsawa (cellulosic an maye gurbinsa da Cell-OH) kamar haka:
Equation (1) ya bayyana halayen etherification na Williamson. RX shine ester acid inorganic, kuma X shine halogen Br, Cl ko ester sulfuric acid. Chloride R-Cl ana amfani dashi gabaɗaya a masana'antu, misali, methyl chloride, ethyl chloride ko chloroacetic acid. Ana cinye adadin stoichiometric na tushe a cikin irin waɗannan halayen. The masana'antu cellulose ether kayayyakin methyl cellulose, ethyl cellulose da carboxymethyl cellulose ne kayayyakin Williamson etherification dauki.
Dalili na amsawa (2) shine ƙarin amsa na epoxides mai tushe (kamar R=H, CH3, ko C2H5) da ƙungiyoyin hydroxyl akan ƙwayoyin cellulose ba tare da cinye tushe ba. Wannan yanayin yana yiwuwa ya ci gaba yayin da aka haifar da sababbin ƙungiyoyin hydroxyl yayin amsawar, wanda ke haifar da samuwar sassan sassan oligoalkylethylene oxide: Irin wannan amsa tare da 1-aziridine (aziridine) zai samar da aminoethyl ether: Cell-O-CH2-CH2-NH2 . Kayayyaki irin su hydroxyethyl cellulose, hydroxypropyl cellulose da hydroxybutyl cellulose duk samfuran epioxidation na tushe-catalyzed.
Dalili na amsawa (3) shine amsawa tsakanin Cell-OH da mahaɗan kwayoyin halitta waɗanda ke ƙunshe da alaƙa biyu masu aiki a cikin matsakaiciyar alkaline, Y ƙungiya ce mai jan wutar lantarki, kamar CN, CONH2, ko SO3-Na +. A yau irin wannan dauki ba a cika yin amfani da shi a masana'antu ba.
Tsarin amsawa (4), etherification tare da diazoalkane ba a haɓaka masana'antu ba tukuna.
- Nau'in ethers cellulose
Cellulose ether na iya zama monoether ko gauraye ether, kuma kaddarorinsa sun bambanta. Akwai ƙananan ƙungiyoyin hydrophilic da aka maye gurbinsu akan macromolecule cellulose, irin su ƙungiyoyin hydroxyethyl, waɗanda za su iya ba da samfurin tare da wani nau'i na solubility na ruwa, yayin da ƙungiyoyin hydrophobic, kamar methyl, ethyl, da dai sauransu, kawai matsakaicin canji Babban digiri zai iya. ba samfurin wani ƙayyadadden ruwa mai narkewa, kuma ƙaramin samfurin da aka maye gurbinsa yana kumbura ne kawai a cikin ruwa ko ana iya narkar da shi a cikin maganin alkali mai narkewa. Tare da zurfin bincike game da kaddarorin ethers na cellulose, sabbin ethers cellulose da filayen aikace-aikacen su za a ci gaba da haɓakawa da samarwa, kuma babban ƙarfin tuƙi shine faɗaɗa kuma ci gaba da ingantaccen kasuwar aikace-aikacen.
Babban dokar tasirin ƙungiyoyi a cikin gauraye ethers akan kaddarorin solubility shine:
1) Ƙara abun ciki na ƙungiyoyin hydrophobic a cikin samfurin don ƙara yawan hydrophobicity na ether kuma rage ma'anar gel;
2) Ƙara abun ciki na ƙungiyoyin hydrophilic (kamar ƙungiyoyin hydroxyethyl) don ƙara ma'anar gel;
3) Ƙungiyar hydroxypropyl na musamman ne, kuma daidaitaccen hydroxypropylation zai iya rage yawan zafin jiki na gel na samfurin, kuma gel zafin jiki na matsakaicin hydroxypropylated samfurin zai sake tashi, amma babban matakin maye gurbin zai rage ma'anar gel; Dalilin shi ne saboda tsarin tsayin sarkar carbon na musamman na ƙungiyar hydroxypropyl, ƙananan matakan hydroxypropylation, raunin haɗin gwiwar hydrogen a ciki da tsakanin kwayoyin halitta a cikin macromolecule cellulose, da ƙungiyoyin hydrophilic hydroxyl a kan sassan reshe. Ruwa ne rinjaye. A gefe guda, idan maye gurbin ya yi girma, za a sami polymerization a kan rukuni na gefe, abin da ke cikin dangi na ƙungiyar hydroxyl zai ragu, hydrophobicity zai karu, kuma za a rage solubility maimakon.
Samar da bincike nacellulose etheryana da dogon tarihi. A cikin 1905, Suida ta fara ba da rahoton etherification na cellulose, wanda aka methylated tare da dimethyl sulfate. Nonionic alkyl ethers Lilienfeld (1912), Dreyfus (1914) da Leuchs (1920) suka ba da izini don ethers cellulose mai-mai narkewa ko mai-mai narkewa, bi da bi. Buchler da Gomberg sun samar da benzyl cellulose a shekarar 1921, carboxymethylcellulose ya fara samar da Jansen a 1918, kuma Hubert ya samar da hydroxyethyl cellulose a cikin 1920. A farkon shekarun 1920, an sayar da carboxymethylcellulose a Jamus. Daga 1937 zuwa 1938, an fara samar da masana'antu na MC da HEC a Amurka. Sweden ta fara samar da EHEC mai narkewar ruwa a cikin 1945. Bayan 1945, samar da ether cellulose ya faɗaɗa cikin sauri a Yammacin Turai, Amurka da Japan. A karshen shekarar 1957, Sin CMC aka fara fara samar a cikin Shanghai Celluloid Factory. A shekara ta 2004, ƙarfin samar da ƙasata zai zama ton 30,000 na ionic ether da ton 10,000 na ether maras ionic. A shekara ta 2007, zai kai ton 100,000 na ionic ether da ton 40,000 na Nonionic ether. Kamfanonin fasahar hadin gwiwa a gida da waje su ma suna ci gaba da samun bunkasuwa, kuma karfin samar da ether na cellulose na kasar Sin yana ci gaba da inganta.
A cikin 'yan shekarun nan, da yawa cellulose monoethers da gauraye ethers tare da daban-daban DS dabi'u, danko, tsarki da kuma rheological Properties an ci gaba da ɓullo da. A halin yanzu, mayar da hankali ga ci gaba a fagen cellulose ethers shine ɗaukar fasahar samar da ci gaba, sabon fasahar shirye-shirye, sababbin kayan aiki, Sabbin samfurori, samfurori masu inganci, da samfurori na tsari ya kamata a yi bincike ta hanyar fasaha.
Lokacin aikawa: Afrilu-28-2024