1.Structure ati ilana igbaradi ti ether cellulose
Nọmba 1 ṣe afihan ilana aṣoju ti awọn ethers cellulose. Ẹyọ bD-anhydroglucose kọọkan (ẹyọ atunṣe ti cellulose) rọpo ẹgbẹ kan ni awọn ipo C (2), C (3) ati C (6), iyẹn ni, o le to awọn ẹgbẹ ether mẹta. Nitori pq inu ati inter-pq hydrogen ticellulose macromolecules, o jẹ soro lati tu ninu omi ati ki o fere gbogbo Organic olomi. Awọn ifihan ti ether awọn ẹgbẹ nipasẹ etherification run intramolecular ati intermolecular hydrogen bonds, mu awọn oniwe-hydrophilicity, ati ki o gidigidi mu awọn oniwe-solubility ni omi media.
Awọn aropo etherified aṣoju jẹ awọn ẹgbẹ alkoxy iwuwo molikula kekere (1 si 4 awọn ọta carbon) tabi awọn ẹgbẹ hydroxyalkyl, eyiti o le paarọ rẹ nipasẹ awọn ẹgbẹ iṣẹ ṣiṣe miiran bii carboxyl, hydroxyl tabi awọn ẹgbẹ amino. Awọn aropo le jẹ ti ọkan, meji tabi diẹ ẹ sii ti o yatọ iru. Pẹlú ẹwọn macromolecular cellulose, awọn ẹgbẹ hydroxyl lori awọn ipo C (2), C (3) ati C (6) ti ẹyọ glukosi kọọkan ti rọpo ni awọn iwọn oriṣiriṣi. Ni pipe, cellulose ether ni gbogbogbo ko ni ilana kemikali pato kan, ayafi fun awọn ọja wọnyẹn ti o rọpo patapata nipasẹ iru ẹgbẹ kan (gbogbo awọn ẹgbẹ hydroxyl mẹta ti rọpo). Awọn ọja wọnyi le ṣee lo fun itupalẹ yàrá ati iwadii, ati pe ko ni iye iṣowo.
(a) Eto gbogbogbo ti awọn ẹya anhydroglucose meji ti ẹwọn molikula ether cellulose, R1~R6=H, tabi aropo Organic;
(b) Ajẹkù pq molikula kan ti carboxymethylhydroxyethyl cellulose, ìwọ̀n ìfidípò carboxymethyl jẹ́ 0.5, ìwọ̀n ìfidípò hydroxyethyl jẹ́ 2.0, àti ìwọ̀n ìfidípò molar jẹ́ 3.0. Ẹya yii ṣe aṣoju ipele aropo apapọ ti awọn ẹgbẹ etherified, ṣugbọn awọn aropo jẹ gangan laileto.
Fun aropo kọọkan, apapọ iye etherification jẹ afihan nipasẹ iwọn iye DS aropo. Iwọn DS jẹ 0 ~ 3, eyiti o jẹ deede si nọmba apapọ ti awọn ẹgbẹ hydroxyl rọpo nipasẹ awọn ẹgbẹ etherification lori ẹyọ anhydroglucose kọọkan.
Fun awọn ethers cellulose hydroxyalkyl, ifarọpo yoo bẹrẹ etherification lati ọdọ awọn ẹgbẹ hydroxyl ọfẹ tuntun, ati iwọn aropo le jẹ iwọn nipasẹ iye MS, iyẹn ni, iwọn molar ti aropo. O ṣe aṣoju nọmba apapọ ti awọn moles ti ifaseyin oluranlowo etherifying ti a ṣafikun si ẹyọ anhydroglucose kọọkan. Aṣoju aṣoju jẹ ohun elo afẹfẹ ethylene ati pe ọja naa ni aropo hydroxyethyl kan. Ni olusin 1, iye MS ti ọja jẹ 3.0.
Ni imọ-jinlẹ, ko si opin oke fun iye MS. Ti iye DS ti iwọn aropo lori ẹgbẹ oruka glukosi kọọkan jẹ mimọ, apapọ pq gigun ti ẹwọn ẹgbẹ etherDiẹ ninu awọn aṣelọpọ tun nigbagbogbo lo ida ibi-pupọ (wt%) ti awọn ẹgbẹ etherification oriṣiriṣi (bii -OCH3 tabi -OC2H4OH) lati ṣe aṣoju ipele aropo ati alefa dipo awọn iye DS ati MS. Iwọn ida ti ẹgbẹ kọọkan ati iye DS tabi MS rẹ le yipada nipasẹ iṣiro rọrun.
Pupọ julọ awọn ethers cellulose jẹ awọn polima ti a yo omi, ati diẹ ninu awọn tun jẹ tiotuka ni apakan ninu awọn nkan ti o ni nkan ti ara. Cellulose ether ni awọn abuda ti ṣiṣe giga, idiyele kekere, sisẹ irọrun, majele kekere ati ọpọlọpọ, ati ibeere ati awọn aaye ohun elo tun n pọ si. Gẹgẹbi oluranlowo oluranlọwọ, ether cellulose ni agbara ohun elo nla ni awọn aaye pupọ ti ile-iṣẹ. le ṣee gba nipasẹ MS/DS.
Awọn ethers Cellulose jẹ ipin ni ibamu si ilana kemikali ti awọn aropo sinu anionic, cationic ati awọn ethers nonionic. Awọn ethers Nonionic le pin si awọn ọja ti o ni omi-tiotuka ati epo.
Awọn ọja ti o ti wa ni iṣelọpọ ti wa ni akojọ ni apa oke ti Table 1. Apa isalẹ ti Table 1 ṣe akojọ diẹ ninu awọn ẹgbẹ etherification ti a mọ, ti ko ti di awọn ọja iṣowo pataki.
Ilana abbreviation ti awọn aropo ether ti o dapọ le jẹ orukọ ni ibamu si ilana alfabeti tabi ipele ti DS (MS), fun apẹẹrẹ, fun 2-hydroxyethyl methylcellulose, abbreviation jẹ HEMC, ati pe o tun le kọ bi MHEC si ṣe afihan aropo methyl.
Awọn ẹgbẹ hydroxyl lori cellulose ko ni irọrun ni irọrun nipasẹ awọn aṣoju etherification, ati ilana etherification nigbagbogbo ni a ṣe labẹ awọn ipo ipilẹ, ni gbogbogbo ni lilo ifọkansi kan ti ojutu olomi NaOH. Awọn cellulose ti wa ni akọkọ akoso sinu swollen alkali cellulose pẹlu NaOH aqueous ojutu, ati ki o faragba etherification lenu pẹlu etherification oluranlowo. Lakoko iṣelọpọ ati igbaradi ti awọn ethers ti a dapọ, awọn oriṣiriṣi awọn aṣoju etherification yẹ ki o lo ni akoko kanna, tabi etherification yẹ ki o gbe ni igbese nipasẹ igbese nipasẹ ifunni lainidii (ti o ba jẹ dandan). Awọn iru ifasẹ mẹrin lo wa ninu etherification ti cellulose, eyiti o jẹ akopọ nipasẹ agbekalẹ ifaseyin (cellulosic ti rọpo nipasẹ Cell-OH) bi atẹle:
Idogba (1) ṣe apejuwe iṣesi etherification Williamson. RX jẹ ester acid inorganic, ati X jẹ halogen Br, Cl tabi ester sulfuric acid. Chloride R-Cl ni gbogbo igba lo ninu ile-iṣẹ, fun apẹẹrẹ, methyl kiloraidi, ethyl kiloraidi tabi chloroacetic acid. Iwọn stoichiometric ti ipilẹ jẹ run ni iru awọn aati. Awọn ọja cellulose ether ti iṣelọpọ ti iṣelọpọ methyl cellulose, ethyl cellulose ati carboxymethyl cellulose jẹ awọn ọja ti iṣesi etherification Williamson.
Fọọmu ifasẹyin (2) jẹ iṣesi afikun ti awọn epoxides-catalyzed (bii R=H, CH3, tabi C2H5) ati awọn ẹgbẹ hydroxyl lori awọn sẹẹli cellulose laisi ipilẹ jijẹ. Ihuwasi yii ṣee ṣe lati tẹsiwaju bi awọn ẹgbẹ hydroxyl tuntun ti wa ni ipilẹṣẹ lakoko iṣesi, ti o yori si dida awọn ẹwọn ẹgbẹ oligoalkylethylene oxide: Idahun kanna pẹlu 1-aziridine (aziridine) yoo dagba aminoethyl ether: Cell-O-CH2-CH2-NH2 . Awọn ọja bii hydroxyethyl cellulose, hydroxypropyl cellulose ati hydroxybutyl cellulose jẹ gbogbo awọn ọja ti ipilẹ-catalyzed epioxidation.
Ilana ifaseyin (3) jẹ iṣesi laarin Cell-OH ati awọn agbo ogun Organic ti o ni awọn ifunmọ ilọpo meji ti nṣiṣe lọwọ ni alabọde ipilẹ, Y jẹ ẹgbẹ yiyọ elekitironi, bii CN, CONH2, tabi SO3-Na +. Loni iru iṣesi yii kii ṣọwọn lo ni ile-iṣẹ.
Ilana idahun (4), etherification pẹlu diazoalkane ko ti ni iṣelọpọ sibẹsibẹ.
- Awọn oriṣi ti cellulose ethers
Cellulose ether le jẹ monoether tabi ether adalu, ati awọn ohun-ini rẹ yatọ. Awọn ẹgbẹ hydrophilic kekere ti o rọpo wa lori macromolecule cellulose, gẹgẹbi awọn ẹgbẹ hydroxyethyl, eyiti o le fun ọja naa ni iwọn kan ti solubility omi, lakoko ti awọn ẹgbẹ hydrophobic, gẹgẹ bi methyl, ethyl, ati bẹbẹ lọ, aropo iwọntunwọnsi Ipele giga le ṣee ṣe. fun ọja naa ni isokuso omi kan, ati ọja ti o rọpo kekere nikan n wú ninu omi tabi o le tuka ni ojutu alkali dilute. Pẹlu iwadi ti o jinlẹ lori awọn ohun-ini ti awọn ethers cellulose, awọn ethers cellulose tuntun ati awọn aaye ohun elo wọn yoo ni idagbasoke nigbagbogbo ati iṣelọpọ, ati pe agbara awakọ ti o tobi julọ ni ọja ohun elo gbooro ati igbagbogbo.
Ofin gbogbogbo ti ipa ti awọn ẹgbẹ ni awọn ethers adalu lori awọn ohun-ini solubility jẹ:
1) Ṣe alekun akoonu ti awọn ẹgbẹ hydrophobic ninu ọja naa lati mu hydrophobicity ti ether ati ki o dinku aaye gel;
2) Ṣe alekun akoonu ti awọn ẹgbẹ hydrophilic (gẹgẹbi awọn ẹgbẹ hydroxyethyl) lati mu aaye gel rẹ pọ si;
3) Ẹgbẹ hydroxypropyl jẹ pataki, ati pe hydroxypropylation to dara le dinku iwọn otutu gel ti ọja naa, ati iwọn otutu gel ti ọja hydroxypropylated alabọde yoo dide lẹẹkansi, ṣugbọn ipele giga ti aropo yoo dinku aaye gel rẹ; Idi naa jẹ nitori eto gigun pq erogba pataki ti ẹgbẹ hydroxypropyl, ipele kekere hydroxypropylation, awọn ifunmọ hydrogen ailagbara ninu ati laarin awọn ohun elo inu macromolecule cellulose, ati awọn ẹgbẹ hydrophilic hydroxyl lori awọn ẹwọn ẹka. Omi jẹ ako. Ni apa keji, ti iyipada ba ga, polymerization yoo wa lori ẹgbẹ ẹgbẹ, akoonu ibatan ti ẹgbẹ hydroxyl yoo dinku, hydrophobicity yoo pọ sii, ati solubility yoo dinku dipo.
Isejade ati iwadi tiether celluloseni o ni kan gun itan. Ni 1905, Suida akọkọ royin etherification ti cellulose, eyiti o jẹ methylated pẹlu dimethyl sulfate. Nonionic alkyl ethers jẹ itọsi nipasẹ Lilienfeld (1912), Dreyfus (1914) ati Leuchs (1920) fun omi-tiotuka tabi awọn ethers cellulose ti o ni epo, lẹsẹsẹ. Buchler ati Gomberg ṣe iṣelọpọ benzyl cellulose ni ọdun 1921, carboxymethyl cellulose jẹ iṣelọpọ akọkọ nipasẹ Jansen ni ọdun 1918, Hubert si ṣe hydroxyethyl cellulose ni ọdun 1920. Ni ibẹrẹ awọn ọdun 1920, carboxymethylcellulose jẹ iṣowo ni Germany. Lati ọdun 1937 si 1938, iṣelọpọ ile-iṣẹ ti MC ati HEC ti waye ni Amẹrika. Sweden bẹrẹ iṣelọpọ ti EHEC ti o ni omi-omi ni ọdun 1945. Lẹhin 1945, iṣelọpọ ti ether cellulose gbooro ni iyara ni Oorun Yuroopu, Amẹrika ati Japan. Ni opin ọdun 1957, China CMC ni akọkọ fi sinu iṣelọpọ ni Ile-iṣẹ Celluloid Shanghai. Ni ọdun 2004, agbara iṣelọpọ ti orilẹ-ede mi yoo jẹ awọn toonu 30,000 ti ether ionic ati awọn toonu 10,000 ti ether ti kii-ionic. Ni ọdun 2007, yoo de awọn tonnu 100,000 ti ionic ether ati 40,000 toonu ti ether Nonionic. Awọn ile-iṣẹ imọ-ẹrọ apapọ ni ile ati ni ilu okeere tun n farahan nigbagbogbo, ati pe agbara iṣelọpọ cellulose ether ti China ati ipele imọ-ẹrọ n ni ilọsiwaju nigbagbogbo.
Ni awọn ọdun aipẹ, ọpọlọpọ awọn monoethers cellulose ati awọn ethers ti o dapọ pẹlu awọn iye DS oriṣiriṣi, viscosities, mimọ ati awọn ohun-ini rheological ti ni idagbasoke nigbagbogbo. Ni bayi, idojukọ idagbasoke ni aaye ti cellulose ethers ni lati gba imọ-ẹrọ iṣelọpọ ilọsiwaju, imọ-ẹrọ igbaradi tuntun, ohun elo tuntun, Awọn ọja tuntun, awọn ọja to gaju, ati awọn ọja eto yẹ ki o ṣe iwadii imọ-ẹrọ.
Akoko ifiweranṣẹ: Oṣu Kẹrin Ọjọ 28-2024