1. Kev txhais thiab kev ua haujlwm ntawm cov khoom tuab
Cov tshuaj ntxiv uas tuaj yeem ua rau cov xim pleev dej viscosity ntau ntxiv hu ua thickeners.
Cov thickeners ua lub luag haujlwm tseem ceeb hauv kev tsim khoom, khaws cia thiab tsim cov txheej txheem.
Lub luag haujlwm tseem ceeb ntawm cov khoom ua kom tuab yog ua kom cov txheej nplaum nplaum ntau dua kom tau raws li qhov xav tau ntawm ntau theem ntawm kev siv. Txawm li cas los xij, qhov viscosity uas cov txheej nplaum xav tau ntawm ntau theem sib txawv. Piv txwv li:
Thaum lub sijhawm khaws cia, nws yog qhov xav tau kom muaj viscosity siab kom tiv thaiv cov xim tsis txhob lo rau;
Thaum lub sijhawm tsim kho, nws yog qhov xav tau kom muaj qhov viscosity nruab nrab kom ntseeg tau tias cov xim muaj kev txhuam zoo yam tsis muaj xim ntau dhau;
Tom qab kev tsim kho, nws tau cia siab tias qhov viscosity tuaj yeem rov qab mus rau qhov viscosity siab tom qab lub sijhawm luv luv (txheej txheem leveling) kom tiv thaiv kev sagging.
Qhov fluidity ntawm cov txheej txheem dej yog non-Newtonian.
Thaum qhov viscosity ntawm cov xim txo qis nrog rau qhov nce ntawm lub zog shear, nws hu ua pseudoplastic fluid, thiab feem ntau ntawm cov xim yog pseudoplastic fluid.
Thaum tus cwj pwm ntws ntawm cov kua dej pseudoplastic muaj feem cuam tshuam nrog nws keeb kwm, uas yog, nws nyob ntawm lub sijhawm, nws hu ua kua dej thixotropic.
Thaum tsim cov txheej txheej, peb feem ntau sim ua kom cov txheej txheej thixotropic, xws li ntxiv cov khoom ntxiv.
Thaum lub thixotropy ntawm lub txheej yog qhov tsim nyog, nws tuaj yeem daws qhov kev tsis sib haum xeeb ntawm ntau theem ntawm lub txheej, thiab ua tau raws li qhov xav tau ntawm cov viscosity sib txawv ntawm lub txheej hauv kev khaws cia, kev tsim kho theem, thiab theem ziab.
Qee cov thickeners tuaj yeem muab cov xim nrog thixotropy siab, yog li nws muaj viscosity siab dua thaum so lossis ntawm qhov nrawm qis (xws li kev khaws cia lossis kev thauj mus los), yog li tiv thaiv cov xim hauv cov xim los ntawm kev poob. Thiab nyob rau hauv qhov nrawm siab (xws li cov txheej txheem txheej), nws muaj viscosity qis, yog li cov txheej txheem muaj txaus ntws thiab leveling.
Thixotropy yog sawv cev los ntawm thixotropic index TI thiab ntsuas los ntawm Brookfield viscometer.
TI = viscosity (ntsuas ntawm 6r/min) / viscosity (ntsuas ntawm 60r/min)
2. Hom thickeners thiab lawv cov teebmeem rau cov khoom txheej
(1) Hom Nyob rau hauv cov nqe lus ntawm cov tshuaj lom neeg sib xyaw, cov thickeners raug muab faib ua ob pawg: organic thiab inorganic.
Cov hom inorganic suav nrog bentonite, attapulgite, txhuas magnesium silicate, lithium magnesium silicate, thiab lwm yam., Cov hom organic xws li methyl cellulose, hydroxyethyl cellulose, polyacrylate, polymethacrylate, acrylic acid lossis methyl Acrylic homopolymer lossis copolymer thiab polyurethane thiab lwm yam.
Los ntawm qhov kev xav ntawm kev cuam tshuam rau cov khoom rheological ntawm cov txheej, cov thickeners raug muab faib ua thixotropic thickeners thiab associative thickeners. Nyob rau hauv cov nqe lus ntawm kev ua tau zoo, tus nqi ntawm thickener yuav tsum tsawg dua thiab qhov thickening effect zoo; nws tsis yooj yim rau eroded los ntawm enzymes; thaum qhov kub lossis pH tus nqi ntawm lub cev hloov pauv, qhov viscosity ntawm txheej yuav tsis raug txo qis, thiab cov xim thiab cov khoom sau yuav tsis raug flocculated. ; Kev ruaj khov zoo; kev khaws cia dej zoo, tsis muaj qhov tshwm sim foaming pom tseeb thiab tsis muaj kev cuam tshuam tsis zoo rau kev ua tau zoo ntawm cov zaj duab xis txheej.
①Cellulose thickener
Cov cellulose thickeners siv rau hauv cov txheej txheem feem ntau yog methylcellulose, hydroxyethylcellulose thiab hydroxypropylmethylcellulose, thiab ob qho kawg feem ntau siv.
Hydroxyethyl cellulose yog ib yam khoom tau los ntawm kev hloov cov hydroxyl pawg ntawm cov glucose units ntawm cov cellulose ntuj nrog cov hydroxyethyl pawg. Cov lus qhia thiab cov qauv ntawm cov khoom feem ntau yog sib txawv raws li qib ntawm kev hloov pauv thiab viscosity.
Cov hom hydroxyethyl cellulose kuj tseem muab faib ua hom yaj ib txwm, hom yaj sai thiab hom ruaj khov. Raws li txoj kev siv, hydroxyethyl cellulose tuaj yeem ntxiv rau ntau theem hauv cov txheej txheem tsim cov txheej txheem. Hom yaj sai tuaj yeem ntxiv ncaj qha rau hauv daim ntawv ntawm cov hmoov qhuav. Txawm li cas los xij, tus nqi pH ntawm lub kaw lus ua ntej ntxiv yuav tsum tsawg dua 7, feem ntau vim tias hydroxyethyl cellulose yaj qeeb qeeb ntawm tus nqi pH qis, thiab muaj sijhawm txaus rau dej nkag mus rau hauv sab hauv ntawm cov khoom me me, thiab tom qab ntawd tus nqi pH nce ntxiv kom nws yaj sai. Cov kauj ruam sib xws kuj tseem siv tau los npaj qee qhov concentration ntawm cov kua nplaum thiab ntxiv rau hauv lub kaw lus txheej.
Hydroxypropyl methylcelluloseyog ib yam khoom tau los ntawm kev hloov pawg hydroxyl ntawm chav glucose ntawm cellulose ntuj nrog pawg methoxy, thaum lwm qhov yog hloov los ntawm pawg hydroxypropyl. Nws cov nyhuv thickening yog qhov zoo ib yam li ntawm hydroxyethyl cellulose. Thiab nws yog resistant rau enzymatic degradation, tab sis nws cov dej solubility tsis zoo li ntawm hydroxyethyl cellulose, thiab nws muaj qhov tsis zoo ntawm gelling thaum rhuab. Rau qhov kho hydroxypropyl methylcellulose nto, nws tuaj yeem ncaj qha ntxiv rau dej thaum siv. Tom qab do thiab dispersing, ntxiv alkaline tshuaj xws li ammonia dej los kho pH tus nqi rau 8-9, thiab do kom txog thaum tag nrho yaj. Rau hydroxypropyl methylcellulose tsis muaj kev kho nto, nws tuaj yeem ntub thiab swelled nrog dej kub saum toj no 85 ° C ua ntej siv, thiab tom qab ntawd txias rau chav tsev kub, tom qab ntawd do nrog dej txias lossis dej khov kom tag nrho yaj nws.
② Cov khoom ua kom tuab tsis muaj zog
Cov khoom siv ua kom tuab no feem ntau yog cov khoom siv av nplaum ua haujlwm, xws li bentonite, magnesium txhuas silicate av nplaum, thiab lwm yam. Nws yog tus cwj pwm hauv qhov ntxiv rau qhov ua kom tuab, nws kuj muaj qhov cuam tshuam zoo rau kev ncua, tuaj yeem tiv thaiv kev poob, thiab yuav tsis cuam tshuam rau qhov tsis kam ntawm cov txheej. Tom qab cov txheej qhuav thiab ua rau hauv zaj duab xis, nws ua haujlwm ua tus sau rau hauv zaj duab xis txheej, thiab lwm yam. Qhov tsis zoo yog tias nws yuav cuam tshuam rau qhov sib npaug ntawm cov txheej.
③ Cov khoom siv ua kom tuab polymer
Cov tshuaj ua kom tuab ntawm cov polymer feem ntau siv rau hauv acrylic thiab polyurethane (cov tshuaj ua kom tuab). Cov tshuaj ua kom tuab ntawm cov acrylic feem ntau yog cov polymers acrylic uas muaj cov pawg carboxyl. Hauv dej uas muaj pH ntawm 8-10, pawg carboxyl yuav tawg thiab o; thaum pH ntau dua 10, nws yuav yaj rau hauv dej thiab poob qhov ua kom tuab, yog li qhov ua kom tuab rhiab heev rau tus nqi pH.
Lub tshuab ua kom tuab ntawm acrylate thickener yog tias nws cov khoom me me tuaj yeem nqus tau rau ntawm qhov chaw ntawm cov khoom me me hauv cov xim pleev xim, thiab tsim ib txheej txheej tom qab alkali o, uas ua rau kom muaj qhov ntim ntawm cov khoom me me latex, cuam tshuam Brownian kev txav ntawm cov khoom me me, thiab ua rau kom muaj viscosity ntawm cov xim pleev xim. ; Qhov thib ob, qhov o ntawm cov khoom me me ua rau kom muaj viscosity ntawm cov dej theem.
(2) Kev cuam tshuam ntawm cov khoom ua kom tuab rau cov khoom txheej
Cov nyhuv ntawm hom thickener rau ntawm cov khoom rheological ntawm lub txheej yog raws li nram no:
Thaum cov khoom ua kom tuab ntxiv, qhov viscosity ntawm cov xim pleev xim nce ntxiv ntau, thiab qhov hloov pauv viscosity yeej zoo ib yam thaum raug lub zog sab nraud.
Nrog rau cov nyhuv ntawm cov thickener, qhov viscosity ntawm cov xim poob sai sai thaum nws raug rau lub zog shear, qhia pseudoplasticity.
Siv cov tshuaj cellulose thickener uas hloov kho hydrophobically (xws li EBS451FQ), ntawm qhov nrawm siab shear, qhov viscosity tseem siab thaum muaj ntau.
Siv cov tshuaj polyurethane thickeners (xws li WT105A), ntawm qhov nrawm siab, qhov viscosity tseem siab thaum qhov ntau.
Siv cov tshuaj acrylic thickeners (xws li ASE60), txawm hais tias qhov viscosity static nce sai thaum muaj ntau, qhov viscosity txo qis sai ntawm qhov shear rate siab dua.
3. Cov khoom sib xyaw ua ke
(1) txoj kev ua kom tuab
Cellulose ether thiab alkali-swellable acrylic thickeners tsuas yog tuaj yeem ua rau cov dej tuab xwb, tab sis tsis muaj qhov cuam tshuam rau lwm yam khoom hauv cov xim dej, thiab lawv tsis tuaj yeem ua rau muaj kev sib cuam tshuam tseem ceeb ntawm cov pigments hauv cov xim thiab cov khoom me me ntawm cov emulsion, yog li qhov rheology ntawm cov xim tsis tuaj yeem hloov kho.
Cov khoom ua kom tuab sib koom ua ke yog cov yam ntxwv uas ntxiv rau qhov tuab los ntawm kev ua kom noo, lawv kuj tuab los ntawm kev sib koom ua ke ntawm lawv tus kheej, nrog cov khoom tawg, thiab nrog lwm yam khoom hauv lub kaw lus. Kev sib koom ua ke no disassociates ntawm cov nqi shear siab thiab rov sib koom ua ke ntawm cov nqi shear qis, tso cai rau rheology ntawm lub txheej kom raug kho.
Lub tshuab ua kom tuab ntawm cov khoom sib txuas ua ke yog tias nws cov molecule yog cov saw hydrophilic linear, ib qho polymer compound nrog lipophilic pawg ntawm ob qho kawg, uas yog, nws muaj hydrophilic thiab hydrophobic pawg hauv cov qauv, yog li nws muaj cov yam ntxwv ntawm surfactant molecules. xwm. Cov khoom sib txuas ua ke no tsis tsuas yog hydrate thiab swell kom tuab cov dej theem, tab sis kuj tsim micelles thaum qhov concentration ntawm nws cov kua dej ntau dua ib qho nqi. Cov micelles tuaj yeem koom nrog cov polymer particles ntawm emulsion thiab cov pigment particles uas tau adsorbed lub dispersant los tsim cov qauv network peb-seem, thiab tau sib txuas thiab entangled kom nce viscosity ntawm lub system.
Qhov tseem ceeb tshaj plaws yog tias cov kev sib koom ua ke no nyob rau hauv lub xeev ntawm kev sib npaug dynamic, thiab cov micelles cuam tshuam tuaj yeem kho lawv qhov chaw thaum raug rau sab nraud lub zog, yog li ntawd lub txheej muaj cov khoom leveling. Tsis tas li ntawd, txij li thaum lub molecule muaj ntau lub micelles, cov qauv no txo qhov kev nyiam ntawm cov dej molecules kom migrate thiab yog li ua rau kom muaj viscosity ntawm cov aqueous theem.
(2) Lub luag haujlwm hauv cov txheej txheem
Feem ntau ntawm cov khoom sib txuas ua ke yog polyurethanes, thiab lawv qhov hnyav molecular sib piv yog nyob nruab nrab ntawm 103-104 xaj ntawm qhov loj, ob xaj ntawm qhov loj dua li cov polyacrylic acid thiab cellulose thickeners nrog qhov hnyav molecular sib piv ntawm 105-106. Vim yog qhov hnyav molecular qis, qhov ntim zoo nce tom qab hydration tsawg dua, yog li nws cov viscosity nkhaus yog flatter dua li ntawm cov khoom sib txuas tsis sib txuas.
Vim tias qhov hnyav molecular qis ntawm cov khoom sib txuas ua ke, nws qhov kev sib txuas ntawm cov khoom sib txuas hauv cov dej theem yog txwv, yog li nws cov nyhuv thickening rau cov dej theem tsis tseem ceeb. Hauv qhov ntau ntawm qhov shear rate qis, qhov kev hloov pauv ntawm cov molecules yog ntau dua li qhov kev puas tsuaj ntawm cov molecules, tag nrho lub kaw lus tswj hwm qhov kev ncua thiab kev sib kis, thiab qhov viscosity ze rau qhov viscosity ntawm cov khoom sib kis (dej). Yog li ntawd, cov khoom sib txuas ua ke ua rau cov xim pleev xim dej pom qhov viscosity qis dua thaum nws nyob hauv thaj chaw qis shear rate.
Cov khoom sib txuas ua ke ua rau lub zog muaj peev xwm ntawm cov molecules ntau ntxiv vim yog kev sib txuas ntawm cov khoom me me hauv theem dispersed. Ua li no, xav tau ntau lub zog los rhuav tshem kev sib txuas ntawm cov molecules ntawm cov nqi shear siab, thiab lub zog shear uas xav tau los ua kom tau tib lub zog shear kuj loj dua, yog li ntawd lub kaw lus qhia txog tus nqi shear siab dua ntawm tus nqi shear siab. Pom tseeb viscosity. Qhov siab dua high-shear viscosity thiab qis dua low-shear viscosity tsuas yog ua rau qhov tsis muaj cov khoom sib txuas hauv cov khoom rheological ntawm cov xim pleev xim, uas yog, ob qho khoom sib txuas tuaj yeem siv ua ke los kho qhov fluidity ntawm cov xim latex. Kev ua tau zoo hloov pauv, kom ua tau raws li qhov xav tau ntawm kev txheej rau hauv zaj duab xis tuab thiab txheej zaj duab xis ntws.
Lub sijhawm tshaj tawm: Plaub Hlis-28-2024