1. Tanthauzo ndi ntchito ya thickener
Zowonjezera zomwe zimatha kuwonjezera kukhuthala kwa utoto wamadzi zimatchedwa thickeners.
Thickeners amagwira ntchito yofunika kwambiri pakupanga, kusunga ndi kumanga zokutira.
Ntchito yaikulu ya thickener ndi kuonjezera mamasukidwe akayendedwe ❖ kuyanika kukwaniritsa zofunika magawo osiyanasiyana ntchito. Komabe, mamasukidwe akayendedwe amafunidwa ndi ❖ kuyanika pa magawo osiyana ndi osiyana. Mwachitsanzo:
Panthawi yosungirako, ndikofunika kuti mukhale ndi kukhuthala kwakukulu kuti muteteze pigment kuti isakhazikike;
Panthawi yomanga, ndikofunikira kukhala ndi mamasukidwe apakati kuti muwonetsetse kuti utoto uli ndi brushability wabwino popanda utoto wopaka utoto wambiri;
Pambuyo pomanga, timayembekeza kuti mamasukidwe akayendedwe amatha kubwereranso kukhuthala kwakanthawi kwakanthawi kochepa (njira yolezera) kuti asagwedezeke.
The fluidity wa zokutira madzi si Newtonian.
Pamene kukhuthala kwa utoto kumachepa ndi kuwonjezeka kwa mphamvu yometa ubweya, imatchedwa pseudoplastic fluid, ndipo utoto wambiri ndi pseudoplastic fluid.
Pamene otaya khalidwe la pseudoplastic madzimadzi okhudzana ndi mbiri yake, ndiko kuti, ndi nthawi amadalira, amatchedwa thixotropic madzimadzi.
Popanga zokutira, nthawi zambiri timayesa mosamala kupanga zokutira thixotropic, monga kuwonjezera zowonjezera.
Pamene thixotropy wa ❖ kuyanika ndi koyenera, akhoza kuthetsa kutsutsana kwa magawo osiyanasiyana a ❖ kuyanika, ndi kukwaniritsa zosowa za luso la kukhuthala kosiyana kwa ❖ kuyanika posungirako, kumanga molingana ndi magawo, ndi kuyanika.
Ena thickeners akhoza endow utoto ndi mkulu thixotropy, kotero kuti ali apamwamba mamasukidwe akayendedwe pa mpumulo kapena pa otsika kukameta ubweya mlingo (monga kusungirako kapena zoyendera), kuteteza pigment mu utoto kukhazikika. Ndipo pansi pa kumeta ubweya wambiri (monga zokutira), imakhala ndi viscosity yochepa, kotero kuti chovalacho chimakhala ndi kutuluka kokwanira ndi kuwongolera.
Thixotropy akuimiridwa ndi thixotropic index TI ndipo anayeza ndi Brookfield viscometer.
TI = kukhuthala (kuyezedwa pa 6r / min) / mamasukidwe akayendedwe (kuyezedwa pa 60r / min)
2. Mitundu ya thickeners ndi zotsatira zake pa ❖ kuyanika katundu
(1) Mitundu Pankhani ya mankhwala, thickeners amagawidwa m'magulu awiri: organic ndi inorganic.
Mitundu ya inorganic imaphatikizapo bentonite, attapulgite, aluminium magnesium silicate, lithiamu magnesium silicate, etc., mitundu ya organic monga methyl cellulose, hydroxyethyl cellulose, polyacrylate, polymethacrylate, acrylic acid kapena methyl Acrylic homopolymer kapena copolymer ndi polyurethane etc.
Malinga ndi mmene chikoka pa rheological zimatha zokutira, thickeners anawagawa thixotropic thickeners ndi associative thickeners. Pazofunika kuchita, kuchuluka kwa thickener kuyenera kukhala kocheperako ndipo makulidwe ake ndi abwino; sikophweka kukokoloka ndi michere; pamene kutentha kapena pH mtengo wa dongosolo umasintha, kukhuthala kwa zokutira sikudzachepetsedwa kwambiri, ndipo pigment ndi filler sizidzagwedezeka. ; Kukhazikika bwino kosungirako; kusungidwa kwamadzi kwabwino, palibe chowoneka bwino chotulutsa thovu komanso palibe zoyipa pamawonekedwe a filimu yokutira.
①Ma cellulose thickener
Ma cellulose thickeners omwe amagwiritsidwa ntchito mu zokutira makamaka methylcellulose, hydroxyethylcellulose ndi hydroxypropylmethylcellulose, ndipo awiri omalizirawa amagwiritsidwa ntchito kwambiri.
Hydroxyethyl cellulose ndi chinthu chomwe chimapezeka posintha magulu a hydroxyl pamagulu a shuga a cellulose wachilengedwe ndi magulu a hydroxyethyl. Mafotokozedwe ndi zitsanzo zazinthuzo zimasiyanitsidwa makamaka ndi mlingo wa kulowetsa ndi kukhuthala.
Mitundu ya hydroxyethyl cellulose imagawidwanso mumtundu wanthawi zonse wosungunuka, mtundu wobalalika mwachangu komanso mtundu wokhazikika wachilengedwe. Ponena za njira yogwiritsira ntchito, hydroxyethyl cellulose imatha kuwonjezeredwa pamagawo osiyanasiyana pakupangira zokutira. Mtundu wobalalitsa mofulumira ukhoza kuwonjezeredwa mwachindunji mu mawonekedwe a ufa wouma. Komabe, pH mtengo wa dongosolo musanayambe kuwonjezera ayenera kukhala zosakwana 7, makamaka chifukwa hydroxyethyl mapadi amasungunuka pang'onopang'ono pa pH mtengo wotsika, ndipo pali nthawi yokwanira kuti madzi alowe mkati mwa tinthu tating'onoting'ono, ndiyeno pH mtengo ukuwonjezeka kuti Isungunuke mwamsanga. Njira zofananira zitha kugwiritsidwanso ntchito pokonzekera gulu linalake la yankho la guluu ndikuwonjezera pamakina opaka.
Hydroxypropyl methylcellulosendi chinthu chopezedwa mwa kusintha gulu la hydroxyl pagawo la shuga la cellulose wachilengedwe ndi gulu la methoxy, pomwe gawo lina limasinthidwa ndi gulu la hydroxypropyl. Kukula kwake kumakhala kofanana ndi hydroxyethyl cellulose. Ndipo imagonjetsedwa ndi kuwonongeka kwa enzymatic, koma kusungunuka kwake m'madzi sikofanana ndi hydroxyethyl cellulose, ndipo imakhala ndi vuto la gelling ikatenthedwa. Kwa hydroxypropyl methylcellulose yopangidwa pamwamba, imatha kuwonjezeredwa mwachindunji kumadzi ikagwiritsidwa ntchito. Mukayambitsa ndi kubalalitsa, onjezerani zinthu zamchere monga madzi ammonia kuti musinthe pH kukhala 8-9, ndikuyambitsanso mpaka kusungunuka kwathunthu. Kwa hydroxypropyl methylcellulose popanda chithandizo chapamwamba, imatha kunyowa ndikutupa ndi madzi otentha pamwamba pa 85 ° C musanagwiritse ntchito, ndiyeno itakhazikika mpaka kutentha, kenaka ndikuyambitsa madzi ozizira kapena madzi oundana kuti musungunuke.
②Zothira madzi
Mtundu uwu wa thickener makamaka ena adamulowetsa mankhwala dongo, monga bentonite, magnesium zotayidwa silicate dongo, etc. Iwo amakhala kuti kuwonjezera pa thickening tingati alinso wabwino kuyimitsidwa tingalepheretse kumira, ndipo sikudzakhudza kukana madzi ❖ kuyanika. Pambuyo pakuwuma ndi kupangidwa kukhala filimu, imakhala ngati yodzaza mu filimu yophimba, ndi zina zotero. Chinthu chosakondweretsa ndichoti chidzakhudza kwambiri kukweza kwa chophimba.
③ Chopangira polima thickener
Synthetic polymer thickeners amagwiritsidwa ntchito kwambiri mu acrylic ndi polyurethane (associative thickeners). Ma Acrylic thickeners nthawi zambiri amakhala ma polima a acrylic okhala ndi magulu a carboxyl. M'madzi okhala ndi pH ya 8-10, gulu la carboxyl limasiyanitsidwa ndikutupa; pamene pH yamtengo wapatali ndi yaikulu kuposa 10, imasungunuka m'madzi ndipo imataya mphamvu yowonjezereka, kotero kuti makulidwe amakhudzidwa kwambiri ndi pH mtengo.
The thickening limagwirira wa acrylate thickener ndi kuti particles ake akhoza adsorbed pamwamba pa latex particles mu utoto, ndi kupanga ❖ kuyanika wosanjikiza pambuyo kutupa kwa alkali, zomwe zimawonjezera voliyumu ya latex particles, amalepheretsa Brownian kuyenda kwa particles, ndi kumawonjezera mamasukidwe akayendedwe a dongosolo utoto. ; Chachiwiri, kutupa kwa thickener kumawonjezera kukhuthala kwa gawo la madzi.
(2) Mphamvu ya thickener pa zinthu zokutira
Zotsatira za mtundu wa thickener pa rheological katundu wokutira ndi motere:
Kuchuluka kwa thickener kuchulukirachulukira, kukhuthala kwa penti kumawonjezeka kwambiri, ndipo kusintha kwa viscosity kumakhala kofanana ndi kukameta ubweya wakunja.
Ndi zotsatira za thickener, kukhuthala kwa utoto kumatsika mofulumira pamene akukameta ubweya, kusonyeza pseudoplasticity.
Pogwiritsa ntchito hydrophobically modified cellulose thickener (monga EBS451FQ), pamtengo wometa ubweya wambiri, kukhuthala kumakhalabe kwakukulu pamene kuchuluka kwake kuli kwakukulu.
Pogwiritsa ntchito associative polyurethane thickeners (monga WT105A), pamiyeso yometa ubweya wambiri, kukhuthala kumakhalabe kwakukulu pamene kuchuluka kwake kuli kwakukulu.
Pogwiritsa ntchito ma acrylic thickeners (monga ASE60), ngakhale kukhuthala kwa static kumakwera mofulumira pamene kuchuluka kwake kuli kwakukulu, kukhuthala kumachepa mofulumira pamlingo wapamwamba wometa ubweya.
3. Associative thickener
(1) makulidwe makina
Ma cellulose ether ndi alkali-swellable acrylic thickeners amatha kukulitsa gawo lamadzi, koma alibe zotsatira zokulitsa pazinthu zina mu utoto wopangidwa ndi madzi, komanso sangathe kuyambitsa kulumikizana kwakukulu pakati pa utoto wa utoto ndi tinthu tating'ono ta emulsion, kotero The rheology ya utoto silingasinthidwe.
Associative thickeners amadziwika kuti kuwonjezera pa thickening mwa hydration, iwonso thicken kudzera mayanjano pakati pawo, ndi particles omwazikana, ndi zigawo zina mu dongosolo. Mgwirizanowu umalekanitsa pamiyeso yayikulu yometa ubweya ndikuyanjananso pamitengo yotsika, zomwe zimapangitsa kuti ma rheology a zokutira asinthe.
The thickening limagwirira wa associative thickener ndi kuti molekyu yake ndi liniya hydrophilic unyolo, polima pawiri ndi lipophilic magulu pa malekezero onse, ndiko kuti, ali hydrophilic ndi hydrophobic magulu mu kapangidwe, choncho ali ndi makhalidwe a mamolekyu surfactant. chilengedwe. Ma molekyulu a thickener oterowo sangangowonjezera madzi ndikutupa kuti apangitse gawo lamadzi, komanso kupanga ma micelles pomwe kuchuluka kwa yankho lamadzi kumaposa mtengo wina. The micelles akhoza kugwirizana ndi polima particles wa emulsion ndi pigment particles kuti adsorbed ndi dispersant kupanga atatu azithunzi-thunzi maukonde dongosolo, ndipo cholumikizidwa ndi kutsekeredwa kuonjezera mamasukidwe akayendedwe a dongosolo.
Chofunika kwambiri ndi chakuti mayanjanowa ali mumkhalidwe wokhazikika, ndipo ma micelles ogwirizana amatha kusintha malo awo pamene akukhudzidwa ndi mphamvu zakunja, kuti zokutira zikhale ndi katundu wofanana. Kuphatikiza apo, popeza molekyu ili ndi ma micelles angapo, kapangidwe kameneka kamachepetsa chizolowezi cha mamolekyu amadzi kuti asamuke ndipo motero kumawonjezera kukhuthala kwa gawo lamadzi.
(2) Udindo wa zokutira
Ambiri mwa ma associative thickeners ndi polyurethanes, ndipo mamolekyu awo olemera ali pakati pa 103-104 magnitude, maulamuliro awiri a kukula kwake kuposa ma polyacrylic acid wamba ndi ma cellulose thickeners okhala ndi mamolekyu olemera pakati pa 105-106. Chifukwa cha kulemera kochepa kwa maselo, mphamvu yowonjezera yowonjezera pambuyo pa hydration imakhala yochepa, kotero kuti mayendedwe ake a viscosity ndi osalala kuposa a non-associative thickeners.
Chifukwa cha kuchepa kwa ma molekyulu a associative thickener, kulowetsedwa kwake kwa intermolecular mu gawo lamadzi kumakhala kochepa, kotero kukhuta kwake pamadzi sikofunikira. Mu otsika kukameta ubweya mlingo osiyanasiyana, mayanjano kutembenuka pakati mamolekyu ndi kuposa mayanjano chiwonongeko pakati mamolekyu, dongosolo lonse amakhala chibadwa kuyimitsidwa ndi kubalalitsidwa boma, ndi mamasukidwe akayendedwe ali pafupi mamasukidwe akayendedwe a sing'anga kubalalikana (madzi). Choncho, associative thickener imapangitsa kuti utoto wopangidwa ndi madzi uwonetsere kutsika kowoneka bwino pamene ili m'dera lotsika la shear.
Ma associative thickeners amawonjezera mphamvu zomwe zingatheke pakati pa mamolekyu chifukwa cha kugwirizana pakati pa particles mu gawo lobalalika. Mwa njira iyi, mphamvu zambiri zimafunika kuti zithetse mgwirizano pakati pa mamolekyu pamtengo wapamwamba wa shear, ndipo mphamvu ya kumeta ubweya yomwe imafunika kuti ikwaniritse kumeta ubweya womwewo imakhalanso yokulirapo, kotero kuti dongosololi likuwonetseratu kumeta ubweya wambiri pamtengo wokwera kwambiri. Kuwoneka mamasukidwe akayendedwe. Kukhuthala kwapamwamba kwambiri komanso kutsika kwamakameta ang'onoang'ono kungangopanganso kusowa kwa zowuma wamba muzinthu za rheological za utoto, ndiko kuti, ma thickeners awiri angagwiritsidwe ntchito kuphatikiza kusintha madzi a utoto wa latex. Kuchita kosinthika, kuti mukwaniritse zofunikira zonse zokutira mufilimu wandiweyani komanso kuyanika filimu.
Nthawi yotumiza: Apr-28-2024