1. Tanthauzo ndi ntchito ya chokhuthala
Zowonjezera zomwe zingawonjezere kwambiri kukhuthala kwa utoto wochokera m'madzi zimatchedwa zokhuthala.
Zothira zimagwira ntchito yofunika kwambiri popanga, kusunga, ndi kupanga zokutira.
Ntchito yaikulu ya chokhuthala ndikuwonjezera kukhuthala kwa chophimbacho kuti chikwaniritse zofunikira pa magawo osiyanasiyana ogwiritsira ntchito. Komabe, kukhuthala komwe kumafunikira ndi chophimbacho pa magawo osiyanasiyana ndi kosiyana. Mwachitsanzo:
Panthawi yosungira, ndikofunikira kukhala ndi kukhuthala kwakukulu kuti utoto usakhazikike;
Pa nthawi yomanga, ndikofunikira kukhala ndi kukhuthala pang'ono kuti utoto ukhale wosavuta kupukuta popanda utoto wambiri;
Pambuyo pomanga, akuyembekeza kuti kukhuthalako kungabwerere msanga ku kukhuthala kwakukulu pambuyo pa nthawi yochepa (njira yolinganiza) kuti zisagwe.
Kusinthasintha kwa zophimba zoperekedwa m'madzi si kwa Newtonian.
Pamene kukhuthala kwa utoto kumachepa ndi kuwonjezeka kwa mphamvu yodula, umatchedwa madzi a pseudoplastic, ndipo utoto wambiri ndi madzi a pseudoplastic.
Pamene kayendedwe ka madzi a pseudoplastic kakugwirizana ndi mbiri yake, ndiko kuti, kamadalira nthawi, kamatchedwa madzi a thixotropic.
Popanga zophimba, nthawi zambiri timayesetsa kupanga zophimba za thixotropic, monga kuwonjezera zowonjezera.
Ngati thixotropy ya chophimbacho ndi yoyenera, imatha kuthetsa kusagwirizana kwa magawo osiyanasiyana a chophimbacho, ndikukwaniritsa zosowa zaukadaulo za kukhuthala kosiyanasiyana kwa chophimbacho m'magawo osungira, kulinganiza zomangamanga, ndi kuumitsa.
Zothina zina zimatha kupatsa utoto thixotropy yambiri, kotero kuti umakhala ndi kukhuthala kwakukulu panthawi yopuma kapena pamlingo wotsika wodula (monga kusungira kapena kunyamula), kuti uteteze utoto kuti usakhazikike. Ndipo pamlingo wapamwamba wodula (monga njira yopaka utoto), umakhala ndi kukhuthala kochepa, kotero kuti utotowo umakhala ndi kuyenda kokwanira komanso kusinthasintha.
Thixotropy imayimiridwa ndi thixotropic index TI ndipo imayesedwa ndi Brookfield viscometer.
TI = kukhuthala (kuyezedwa pa 6r/min)/kukhuthala (kuyezedwa pa 60r/min)
2. Mitundu ya zokhuthala ndi momwe zimakhudzira mphamvu zophikira
(1) Mitundu Ponena za kapangidwe ka mankhwala, zokhuthala zimagawidwa m'magulu awiri: zachilengedwe ndi zosapangidwa ndi chilengedwe.
Mitundu ya inorganic ndi monga bentonite, attapulgite, aluminiyamu magnesium silicate, lithium magnesium silicate, ndi zina zotero, mitundu ya organic monga methyl cellulose, hydroxyethyl cellulose, polyacrylate, polymethacrylate, acrylic acid kapena methyl Acrylic homopolymer kapena copolymer ndi polyurethane ndi zina zotero.
Kuchokera pakuwona momwe zimakhudzira mphamvu ya rheological ya zokutira, zothina zimagawidwa m'magulu awiri: zothina za thixotropic ndi zothina za associative. Ponena za zofunikira pakugwira ntchito, kuchuluka kwa chothina kuyenera kukhala kochepa ndipo mphamvu yake yothina ndi yabwino; sizosavuta kuwonongeka ndi ma enzyme; kutentha kapena pH ya dongosolo ikasintha, kukhuthala kwa chophimba sikudzachepa kwambiri, ndipo utoto ndi chodzaza sizidzasungunuka. ; Kukhazikika bwino kosungira; kusunga madzi bwino, palibe chinthu chodziwika bwino chotulutsa thovu komanso palibe zotsatira zoyipa pa magwiridwe antchito a filimu yokutira.
①Chokhuthala cha selulosi
Zinthu zothina za cellulose zomwe zimagwiritsidwa ntchito popanga zokutira ndi methylcellulose, hydroxyethylcellulose ndi hydroxypropylmethylcellulose, ndipo ziwiri zomalizazi zimagwiritsidwa ntchito kwambiri.
Hydroxyethyl cellulose ndi chinthu chomwe chimapezeka posintha magulu a hydroxyl pamagulu a shuga a cellulose yachilengedwe ndi magulu a hydroxyethyl. Mafotokozedwe ndi mitundu ya zinthuzi zimasiyanitsidwa makamaka malinga ndi kuchuluka kwa kusintha ndi kukhuthala.
Mitundu ya hydroxyethyl cellulose imagawidwanso m'magulu awiri: mtundu wosungunuka bwino, mtundu wofalikira mwachangu, ndi mtundu wokhazikika pazamoyo. Ponena za njira yogwiritsira ntchito, hydroxyethyl cellulose imatha kuwonjezeredwa pazigawo zosiyanasiyana popanga utoto. Mtundu wofalikira mwachangu ukhoza kuwonjezeredwa mwachindunji mu mawonekedwe a ufa wouma. Komabe, pH ya dongosolo isanawonjezedwe iyenera kukhala yochepera 7, makamaka chifukwa hydroxyethyl cellulose imasungunuka pang'onopang'ono pa pH yotsika, ndipo pamakhala nthawi yokwanira kuti madzi alowe mkati mwa tinthu tating'onoting'ono, kenako pH imawonjezeka kuti isungunuke mwachangu. Masitepe ofanana angagwiritsidwenso ntchito kukonzekera kuchuluka kwa guluu ndikuwonjezera ku dongosolo lophimba.
Hydroxypropyl methylcelluloseNdi chinthu chomwe chimapezeka posintha gulu la hydroxyl pa unit ya shuga ya cellulose yachilengedwe ndi gulu la methoxy, pomwe gawo lina limasinthidwa ndi gulu la hydroxypropyl. Mphamvu yake yokhuthala imakhala yofanana ndi ya hydroxyethyl cellulose. Ndipo imalimbana ndi kuwonongeka kwa enzymatic, koma kusungunuka kwa madzi sikwabwino ngati kwa hydroxyethyl cellulose, ndipo ili ndi vuto la gelling ikatenthedwa. Pa hydroxypropyl methylcellulose yokonzedwa pamwamba, imatha kuwonjezeredwa mwachindunji m'madzi ikagwiritsidwa ntchito. Mukasakaniza ndi kusakaniza, onjezerani zinthu zamchere monga madzi a ammonia kuti musinthe pH kukhala 8-9, ndikusakaniza mpaka itasungunuka kwathunthu. Pa hydroxypropyl methylcellulose popanda kukonzedwa pamwamba, imatha kunyowa ndi kufufutidwa ndi madzi otentha opitilira 85°C musanagwiritse ntchito, kenako kuziziritsidwa kutentha kwa chipinda, kenako ndikusakaniza ndi madzi ozizira kapena madzi oundana kuti isungunuke kwathunthu.
②Chokhuthala chosapanga dzimbiri
Mtundu uwu wa chokhuthala makamaka ndi zinthu zina zadothi zogwiritsidwa ntchito, monga bentonite, magnesium aluminum silicate dongo, ndi zina zotero. Umadziwika kuti kuwonjezera pa kukhuthala, umakhalanso ndi mphamvu yabwino yoyimitsira, umatha kuletsa kumira, ndipo sudzakhudza kukana kwa madzi kwa chophimbacho. Chophimbacho chikauma ndikupanga filimu, chimagwira ntchito ngati chodzaza mu filimu yophimba, ndi zina zotero. Chinthu choipa ndichakuti chidzakhudza kwambiri kulinganiza kwa chophimbacho.
③ Chokhuthala cha polima chopangidwa
Zothina za polymer zopangidwa ndi polymer zimagwiritsidwa ntchito kwambiri mu acrylic ndi polyurethane (zothina za associate). Zothina za acrylic makamaka ndi ma polima a acrylic okhala ndi magulu a carboxyl. M'madzi okhala ndi pH ya 8-10, gulu la carboxyl limalekanitsidwa ndi kutupa; pH ikapitirira 10, imasungunuka m'madzi ndikutaya mphamvu yothina, kotero mphamvu yothina imakhala yogwirizana kwambiri ndi pH.
Njira yokulira ya acrylate thickener ndi yakuti tinthu take titha kunyamulidwa pamwamba pa tinthu ta latex mu utoto, ndikupanga chophimba pambuyo pa kutupa kwa alkali, komwe kumawonjezera kuchuluka kwa tinthu ta latex, kumalepheretsa kuyenda kwa Brownian kwa tinthu tating'onoting'ono, ndikuwonjezera kukhuthala kwa dongosolo la utoto. ; Chachiwiri, kutupa kwa thickener kumawonjezera kukhuthala kwa gawo la madzi.
(2) Mphamvu ya chokhuthala pa kapangidwe kake ka utoto
Zotsatira za mtundu wa thickener pa rheological katundu wa chophimba ndi motere:
Pamene kuchuluka kwa chokhuthala kukuwonjezeka, kukhuthala kwa utoto kosasinthasintha kumawonjezeka kwambiri, ndipo kusintha kwa kukhuthala kumakhala kofanana kwambiri pamene kumagwiritsidwa ntchito ndi mphamvu yakunja yocheka.
Ndi mphamvu ya chokhuthala, kukhuthala kwa utoto kumatsika mofulumira ukagwiritsidwa ntchito ndi mphamvu yocheka, zomwe zimasonyeza kuti utotowo ndi wosalimba.
Pogwiritsa ntchito chothirira cha cellulose chosinthidwa ndi hydrophobically (monga EBS451FQ), pamlingo wapamwamba kwambiri, kukhuthala kumakhalabe kwakukulu pamene kuchuluka kuli kwakukulu.
Pogwiritsa ntchito zinthu zothina za polyurethane (monga WT105A), pamlingo wapamwamba kwambiri, kukhuthala kumakhalabe kwakukulu pamene kuchuluka kwake kuli kwakukulu.
Pogwiritsa ntchito zothina za acrylic (monga ASE60), ngakhale kuti kukhuthala kwa static kumakwera mofulumira pamene kuchuluka kuli kwakukulu, kukhuthala kumachepa mofulumira pamlingo wapamwamba wodula.
3. Chokhuthala chogwirizana
(1) njira yokhuthala
Cellulose ether ndi acrylic thickeners zomwe zimakhuthala madzi zimangowonjezera mphamvu ya madzi, koma sizimawonjezera mphamvu ya zinthu zina mu utoto wopangidwa ndi madzi, komanso sizingayambitse kuyanjana kwakukulu pakati pa utoto ndi tinthu ta emulsion, kotero rheology ya utoto singathe kusinthidwa.
Zokhuthala zolumikizana zimadziwika kuti kuwonjezera pa kukhuthala kudzera mu madzi, zimakhuthalanso kudzera mu mgwirizano pakati pawo, ndi tinthu tomwe timafalikira, komanso ndi zinthu zina zomwe zili mu dongosololi. Kugwirizana kumeneku kumalekanitsidwa ndi kuchuluka kwa kucheka kwapamwamba ndipo kumalumikizananso ndi kuchuluka kwa kucheka kwapansi, zomwe zimapangitsa kuti rheology ya chophimbacho isinthidwe.
Njira yothira ya associative thickener ndi yakuti molekyu yake ndi unyolo wozungulira wa hydrophilic, polymer compound yokhala ndi magulu a lipophilic mbali zonse ziwiri, ndiko kuti, ili ndi magulu a hydrophilic ndi hydrophobic m'mapangidwe ake, kotero ili ndi makhalidwe a mamolekyu a surfactant. Mamolekyu othira oterewa samangothira madzi ndi kutupa kuti achulukitse gawo la madzi, komanso amapanga ma micelles pamene kuchuluka kwa yankho lake lamadzi kumaposa mtengo winawake. Ma micelles amatha kugwirizana ndi tinthu ta polymer ta emulsion ndi tinthu ta pigment zomwe zakhudza dispersant kuti apange kapangidwe ka netiweki ya magawo atatu, ndipo zimalumikizidwa ndikulumikizidwa kuti ziwonjezere kukhuthala kwa dongosolo.
Chofunika kwambiri n’chakuti mayanjano amenewa ali mu mkhalidwe wa dynamic balance, ndipo ma micelles ogwirizana nawo amatha kusintha malo awo akamakumana ndi mphamvu zakunja, kotero kuti chophimbacho chimakhala ndi mphamvu zolinganiza. Kuphatikiza apo, popeza molekyuluyi ili ndi ma micelles angapo, kapangidwe kameneka kamachepetsa chizolowezi cha mamolekyu amadzi kusamuka motero kumawonjezera kukhuthala kwa gawo lamadzi.
(2) Udindo mu zophimba
Zambiri mwa zokhuthala zolumikizana ndi polyurethanes, ndipo kulemera kwawo kwa mamolekyulu kuli pakati pa 103-104, ma oda awiri otsika kuposa polyacrylic acid wamba ndi cellulose thickeners okhala ndi kulemera kwa mamolekyulu pakati pa 105-106. Chifukwa cha kulemera kochepa kwa mamolekyulu, kuchuluka kwamphamvu kumawonjezeka pambuyo pa hydration kumakhala kochepa, kotero kupindika kwake kwa viscosity kumakhala kosalala kuposa kwa zokhuthala zosakhudzana ndi associative.
Chifukwa cha kulemera kochepa kwa mamolekyulu a associative thickener, kusakanikirana kwake pakati pa mamolekyulu mu gawo la madzi ndi kochepa, kotero mphamvu yake yokhuthala pa gawo la madzi si yofunikira kwenikweni. Mu shear rate range yotsika, kusinthika kwa mgwirizano pakati pa mamolekyulu kuli kochulukirapo kuposa kuwonongeka kwa mgwirizano pakati pa mamolekyulu, dongosolo lonse limasunga mkhalidwe woyimitsidwa ndi kufalikira, ndipo kukhuthala kuli pafupi ndi kukhuthala kwa dispersion medium (madzi). Chifukwa chake, associative thickener imapangitsa kuti utoto wopangidwa ndi madzi uwonetse kukhuthala kochepa pamene uli m'dera lotsika la shear rate.
Zothina zolumikizana zimawonjezera mphamvu zomwe zingatheke pakati pa mamolekyu chifukwa cha mgwirizano pakati pa tinthu tating'onoting'ono mu gawo logawanika. Mwanjira imeneyi, mphamvu zambiri zimafunika kuti tiwononge mgwirizano pakati pa mamolekyu pamlingo wapamwamba wa shear, ndipo mphamvu yothina yomwe imafunika kuti tikwaniritse kupsinjika komweko ndi yayikulu, kotero kuti dongosololi likuwonetsa liwiro lalikulu la shear pamlingo wapamwamba wa shear. Kukhuthala kooneka. Kukhuthala kwakukulu kwa shear komanso kukhuthala kochepa kwa shear kungapangitse kuti pasakhale zothina zodziwika bwino mu rheological properties za utoto, ndiko kuti, zothina ziwirizi zitha kugwiritsidwa ntchito pamodzi kuti zisinthe kusinthasintha kwa utoto wa latex. Kugwira ntchito mosiyanasiyana, kukwaniritsa zofunikira zonse za kupaka utoto kukhala filimu yokhuthala ndi kayendedwe ka filimu yophimba.
Nthawi yotumizira: Epulo-28-2024