1. Tsarin tsari da shiri na cellulose ether
Siffa ta 1 ta nuna tsarin da aka saba amfani da shi na ethers na cellulose. Kowace naúrar bD-anhydroglucose (naúrar maimaituwa ta cellulose) tana maye gurbin rukuni ɗaya a matsayin C (2), C (3) da C (6), wato, za a iya samun har zuwa ƙungiyoyin ether uku. Saboda haɗin hydrogen na cikin sarka da sarka tsakanin sarka naƙwayoyin cellulose, yana da wuya a narke a cikin ruwa da kusan dukkan sinadarai masu narkewa na halitta. Gabatar da ƙungiyoyin ether ta hanyar etherification yana lalata haɗin hydrogen na ciki da na tsakiya, yana inganta hydrophilicity, kuma yana inganta narkewarsa sosai a cikin hanyoyin ruwa.
Abubuwan da aka fi sani da etherified sune ƙananan ƙwayoyin alkoxy (ƙwayoyin carbon 1 zuwa 4) ko ƙungiyoyin hydroxyalkyl, waɗanda za a iya maye gurbinsu da wasu ƙungiyoyi masu aiki kamar carboxyl, hydroxyl ko amino groups. Abubuwan da aka samu na iya zama nau'i ɗaya, biyu ko fiye daban-daban. Tare da sarkar macromolecular ta cellulose, ana maye gurbin ƙungiyoyin hydroxyl akan matsayin C(2), C(3) da C(6) na kowane rukunin glucose a cikin rabo daban-daban. A taƙaice dai, cellulose ether gabaɗaya ba shi da takamaiman tsarin sinadarai, sai dai waɗancan samfuran da aka maye gurbinsu gaba ɗaya da nau'in rukuni ɗaya (dukkan ƙungiyoyin hydroxyl uku an maye gurbinsu). Ana iya amfani da waɗannan samfuran ne kawai don nazarin dakin gwaje-gwaje da bincike, kuma ba su da ƙimar kasuwanci.
(a) Tsarin gabaɗaya na raka'a biyu na anhydroglucose na sarkar ƙwayoyin cellulose ether, R1~R6=H, ko wani abu na halitta;
(b) Wani yanki na sarkar ƙwayoyin cuta na carboxymethylhydroxyethyl cellulose, matakin maye gurbin carboxymethyl shine 0.5, matakin maye gurbin hydroxyethyl shine 2.0, kuma matakin maye gurbin molar shine 3.0. Wannan tsari yana wakiltar matsakaicin matakin maye gurbin ƙungiyoyin etherified, amma abubuwan maye gurbin a zahiri bazuwar ne.
Ga kowane madadin, jimlar adadin etherification ana bayyana shi ta hanyar matakin ƙimar maye gurbin DS. Jerin DS shine 0~3, wanda yayi daidai da matsakaicin adadin ƙungiyoyin hydroxyl da aka maye gurbinsu da ƙungiyoyin etherification akan kowane rukunin anhydroglucose.
Ga hydroxyalkyl cellulose ethers, amsawar maye gurbin zai fara etherification daga sabbin ƙungiyoyin hydroxyl kyauta, kuma ana iya ƙididdige matakin maye gurbin ta hanyar ƙimar MS, wato, matakin molar na maye gurbin. Yana wakiltar matsakaicin adadin moles na etherifying agent reactant da aka ƙara a kowane naúrar anhydroglucose. Mai amsawa na yau da kullun shine ethylene oxide kuma samfurin yana da hydroxyethyl substituent. A cikin Hoto na 1, ƙimar MS na samfurin shine 3.0.
A ka'ida, babu iyaka ta sama ga ƙimar MS. Idan an san ƙimar DS na matakin maye gurbin a kowace ƙungiyar zoben glucose, matsakaicin tsawon sarkar sarkar gefen ether Wasu masana'antun kuma galibi suna amfani da ɓangaren taro (wt%) na ƙungiyoyin etherification daban-daban (kamar -OCH3 ko -OC2H4OH) don wakiltar matakin maye gurbin da digiri maimakon ƙimar DS da MS. Ana iya canza ɓangaren taro na kowane rukuni da ƙimar DS ko MS ta hanyar lissafi mai sauƙi.
Yawancin ƙwayoyin cellulose ethers polymers ne masu narkewa cikin ruwa, wasu kuma suna narkewa kaɗan a cikin sinadarai masu narkewa na halitta. Cellulose ether yana da halaye na inganci mai yawa, ƙarancin farashi, sauƙin sarrafawa, ƙarancin guba da nau'ikan iri-iri, kuma buƙatun da filayen aikace-aikacen har yanzu suna faɗaɗa. A matsayin wakili mai taimako, cellulose ether yana da babban yuwuwar amfani a fannoni daban-daban na masana'antu. MS/DS na iya samun sa.
Ana rarraba ƙwayoyin cellulose bisa ga tsarin sinadarai na abubuwan da ke cikin su zuwa anionic, cationic da nonionic ethers. Ana iya raba ƙwayoyin nonionic zuwa samfuran da ke narkewa cikin ruwa da kuma samfuran da ke narkewa cikin mai.
An jera kayayyakin da aka haɓaka a masana'antu a saman Tebur 1. Ƙasan Tebur 1 ya lissafa wasu ƙungiyoyin etherification da aka sani, waɗanda ba su zama muhimman samfuran kasuwanci ba tukuna.
Ana iya sanya wa jerin gajerun abubuwan maye gurbin ether suna bisa ga tsarin haruffa ko matakin DS (MS), misali, ga 2-hydroxyethyl methylcellulose, taƙaitaccen shine HEMC, kuma ana iya rubuta shi azaman MHEC don haskaka madadin methyl.
Rukunin hydroxyl da ke kan cellulose ba sa samun sauƙin shiga ta hanyar sinadaran etherification, kuma yawanci ana gudanar da tsarin etherification ne a ƙarƙashin yanayin alkaline, gabaɗaya ana amfani da wani adadin ruwan NaOH. Da farko ana samar da cellulose zuwa kumbura alkali cellulose tare da ruwan NaOH, sannan a yi aikin etherification tare da wakilin etherification. A lokacin samarwa da shirya gaurayen ethers, ya kamata a yi amfani da nau'ikan etherification daban-daban a lokaci guda, ko kuma a yi etherification mataki-mataki ta hanyar ciyarwa lokaci-lokaci (idan ya cancanta). Akwai nau'ikan amsawa guda huɗu a cikin etherification na cellulose, waɗanda aka taƙaita ta hanyar dabarar amsawa (an maye gurbin cellulosic da Cell-OH) kamar haka:
Daidaito (1) ta bayyana amsawar etherification ta Williamson. RX ester ne na inorganic acid, kuma X shine halogen Br, Cl ko sulfuric acid ester. Ana amfani da Chloride R-Cl gabaɗaya a masana'antu, misali, methyl chloride, ethyl chloride ko chloroacetic acid. Ana amfani da adadin tushe mai ƙarfi a cikin irin waɗannan halayen. Samfuran ether na cellulose ether na masana'antu, methyl cellulose, ethyl cellulose da carboxymethyl cellulose sune samfuran amsawar etherification ta Williamson.
Tsarin amsawa (2) shine ƙarin amsawar epoxides masu tushe (kamar R=H, CH3, ko C2H5) da ƙungiyoyin hydroxyl akan ƙwayoyin cellulose ba tare da cinye tushe ba. Wannan amsawar na iya ci gaba yayin da ake samar da sabbin ƙungiyoyin hydroxyl yayin amsawar, wanda ke haifar da samuwar sarƙoƙin gefe na oligoalkyletethylene oxide: Irin wannan amsawar tare da 1-aziridine (aziridine) zai samar da aminoethyl ether: Cell-O-CH2-CH2-NH2. Kayayyaki kamar hydroxyethyl cellulose, hydroxypropyl cellulose da hydroxybutyl cellulose duk samfuran epoxidation ne na tushe.
Tsarin amsawa (3) shine amsawar da ke tsakanin Cell-OH da mahaɗan halitta waɗanda ke ɗauke da haɗin gwiwa biyu masu aiki a cikin matsakaiciyar alkaline, Y ƙungiya ce mai cire electron, kamar CN, CONH2, ko SO3-Na+. A yau ba a cika amfani da wannan nau'in amsawar a masana'antu ba.
Tsarin amsawa (4), etherification tare da diazoalkane bai riga ya zama masana'antu ba tukuna.
- Nau'ikan cellulose ethers
Cellulose ether na iya zama monoether ko gauraye ether, kuma halayensa sun bambanta. Akwai ƙungiyoyin hydrophilic marasa maye gurbinsu a kan ƙwayoyin cellulose macromolecule, kamar ƙungiyoyin hydroxyethyl, waɗanda zasu iya ba samfurin wani matakin narkewar ruwa, yayin da ga ƙungiyoyin hydrophobic, kamar methyl, ethyl, da sauransu, matsakaicin maye gurbinsu ne kawai Babban matakin zai iya ba samfurin wani takamaiman narkewar ruwa, kuma samfurin da aka maye gurbinsa kawai yana kumbura cikin ruwa ko kuma ana iya narkar da shi a cikin maganin alkali mai narkewa. Tare da zurfafa bincike kan halayen ethers na cellulose, sabbin ethers na cellulose da filayen aikace-aikacensu za a ci gaba da haɓaka da samar da su, kuma babban ƙarfin motsawa shine kasuwar aikace-aikacen da aka faɗaɗa kuma aka ci gaba da ingantawa.
Dokar gabaɗaya game da tasirin ƙungiyoyi a cikin gaurayen ethers akan halayen narkewa shine:
1) Ƙara yawan ƙungiyoyin hydrophobic a cikin samfurin don ƙara yawan hydrophobic na ether da rage ma'aunin gel;
2) Ƙara yawan ƙungiyoyin hydrophilic (kamar ƙungiyoyin hydroxyethyl) don ƙara yawan zafin gel ɗinsa;
3) Rukunin hydroxypropyl na musamman ne, kuma ingantaccen hydroxypropylation zai iya rage zafin gel na samfurin, kuma zafin gel na samfurin hydroxypropyl mai matsakaici zai sake tashi, amma babban matakin maye gurbin zai rage wurin gel ɗinsa; Dalilin shine saboda tsarin tsawon sarkar carbon na musamman na rukunin hydroxypropyl, ƙarancin matakin hydroxypropyl, raunin haɗin hydrogen a cikin da tsakanin ƙwayoyin halitta a cikin macromolecule cellulose, da ƙungiyoyin hydroxyl hydrophilic akan sarƙoƙin reshe. Ruwa yana da rinjaye. A gefe guda kuma, idan maye gurbin ya yi yawa, za a sami polymerization a rukunin gefe, abun da ke cikin rukunin hydroxyl zai ragu, haɓakar hydrophobic zai ƙaru, kuma za a rage narkewar ruwa maimakon haka.
Samarwa da bincike nacellulose etheryana da dogon tarihi. A shekarar 1905, Suida ta fara bayar da rahoton etherification na cellulose, wanda aka yi masa methylation da dimethyl sulfate. Lilienfeld (1912), Dreyfus (1914) da Leuchs (1920) sun yi lasisin mallakar ƙwayoyin cellulose masu narkewa cikin ruwa ko mai narkewa cikin ruwa, bi da bi. Buchler da Gomberg sun samar da benzyl cellulose a shekarar 1921, Jansen ne ya fara samar da carboxymethyl cellulose a shekarar 1918, kuma Hubert ya samar da hydroxyethyl cellulose a shekarar 1920. A farkon shekarun 1920, an fara 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 narkewa cikin ruwa a shekarar 1945. Bayan 1945, samar da cellulose ether ya faɗaɗa cikin sauri a Yammacin Turai, Amurka da Japan. A ƙarshen shekarar 1957, an fara samar da China CMC a masana'antar Celluloid ta Shanghai. Nan da shekarar 2004, ƙarfin samar da ƙasata zai kai tan 30,000 na ionic ether da tan 10,000 na non-ionic ether. Nan da shekarar 2007, zai kai tan 100,000 na ionic ether da tan 40,000 na Nonionic ether. Kamfanonin fasaha na haɗin gwiwa a gida da waje suma suna ci gaba da bunƙasa, kuma ƙarfin samar da cellulose ether na China da matakin fasaha yana ci gaba da ingantawa.
A cikin 'yan shekarun nan, an ci gaba da haɓaka da yawa daga cikin ƙwayoyin cellulose monoethers da gauraye ethers tare da ƙimar DS daban-daban, viscosities, tsarki da halayen rheological. A halin yanzu, babban abin da ake mayar da hankali a kai a fannin ƙwayoyin cellulose shine a rungumi fasahar samarwa ta zamani, sabuwar fasahar shiri, sabbin kayan aiki, sabbin kayayyaki, sabbin kayayyaki masu inganci, da samfuran da aka tsara a fannin fasaha.
Lokacin Saƙo: Afrilu-28-2024