Nyob rau hauv cov txheej txheem pigment ntau lawm, txawm zoo npaum li cas cov pigment hmoov yog hauv av, yuav muaj ib co aggregated thiab flocculated hais. Nyob rau hauv cov txheej txheem ntawm kev thauj mus los thiab cia, cov xim yuav ntxiv flocculated mus rau hauv cov khoom loj vim extrusion thiab ya raws, thiab cov xim zoo dua, qhov loj ntawm qhov chaw thiab ntau dua lub zog saum npoo, qhov yooj yim dua nws yog flocculate ua ke. Yog tias kho nrog cov surfactants tsim nyog, cov flocculated loj hais yog yooj yim dispersed thaum siv, thiab dispersion mechanism yog raws li nram no:
1. ntub dej
Lub dispersion ntawm inorganic pigment hmoov nyob rau hauv cov kua feem ntau mus los ntawm peb theem hauv qab no:
① Rau qhov ntub dej ntawm cov hmoov, cov kua yuav tsum tsis yog ntub dej ntawm cov hmoov, tab sis kuj hloov cov huab cua thiab noo noo ntawm cov hmoov av;
② Tom qab dhau los ntawm cov hmoov ntub dej thiab tshem tawm cov huab cua thiab noo noo ntawm cov khoom, cov flocs thiab aggregates hauv cov hmoov pigment raug rhuav tshem;
③ Lub wetted thiab rhuav tshem flocs thiab aggregate hmoov tuav ib tug ruaj khov dispersion xeev nyob rau hauv cov kua. Uas yog hais, dispersion yog txheej txheem ntawm wetting-dispersing-ua kom lub dispersion ruaj khov.
Nyob rau hauv ib txwm muaj xwm txheej, cov pigments inorganic tsis tshua qhuav ua ntej siv, thiab cov xim ntawm lub ntsej muag tsis yog tsuas yog tov nrog huab cua, tab sis kuj absorbs ib txheej ntawm dej zaj duab xis. Tus nqi ntawm cov dej feem ntau adsorbed rau saum npoo ntawm cov xim yog sib npaug rau cov dej uas yuav tsum tau ua ib zaj duab xis monomolecular ntawm cov khoom nto. Piv txwv li, thaj chaw saum npoo av ib gram ntawm TiO2 yog 10m2, lub thickness ntawm cov dej molecule adsorption txheej yog 10 × 10-10m, thiab cov dej xav tau los ntawm cov yeeb yaj kiab monomolecular yog li ntawm 0.3 feem pua ntawm qhov hnyav ntawm cov xim , yog li cov ntsiab lus noo noo hauv cov xim kuj yog ib qho tseem ceeb cuam tshuam rau nws txoj kev ua haujlwm tawg. ib. Seb cov khoom yog wetted los yog tsis tuaj yeem txiav txim raws li nws lub kaum sab xis. Lub kaum sab xis ntawm 0 degree txhais tau hais tias nws ntub tag, thiab cov kua yog tag nrho ntawm cov khoom; Lub kaum sab xis ntawm 180 degree txhais tau hais tias nws tsis ntub tag nrho, thiab cov kua ua rau ntawm qhov chaw hauv daim ntawv ntawm cov tee dej. khoom nto.
Txawm hais tias cov khoom tuaj yeem ua kom zoo wetted hauv cov kua tuaj yeem txiav txim tsis yog los ntawm qhov loj ntawm lub kaum sab xis, tab sis kuj los ntawm kev ntsuas qhov loj ntawm nws cov cua sov ntawm ntub dej. Feem ntau, cov hmoov av hydrophilic (xws li TiO2) muaj cov cua kub loj ntawm cov dej ntub dej hauv cov kua polar, thiab hauv cov kua dej uas tsis yog-polar Cov cua sov ntawm cov dej ntub dej hauv cov kua polar yog me me, thaum tshav kub ntawm ntub dej ntawm cov hmoov hydrophobic nyob rau hauv cov polar thiab cov dej tsis muaj polar. yog roughly tas li.
Qhov kev daws teeb meem ceev thiab qhov ntim ntim ntawm cov hmoov hmoov hauv cov kua kuj tuaj yeem txiav txim siab txog qhov ntub dej. Cov khoom uas muaj polarity siab xws li TiO2 muaj qhov ntim me me nyob rau hauv ib qho kev daws teeb meem loj, thiab cov khoom me me hauv cov kua polar tsawg. yog loj; non-polar khoom hmoov feem ntau muaj cov sedimentation loj. Tom qab ntxiv cov kev kho mob surfactant, vim hais tias cov surfactant molecules muaj zog taw qhia thiab adsorbed rau saum npoo ntawm cov khoom, nws yuav pab txo qhov nro ntawm cov kua thiab txhim kho nws cov ntub dej thiab dispersing zog.
2. Hluav taws xob repulsion (ξ peev xwm)
Lub dispersion thiab dispersion stability ntawm inorganic pigments nyob rau hauv aqueous tov yog tsuas yog txiav txim los ntawm lawv cov hluav taws xob repulsion nyob rau hauv dej, uas yog, lub peev xwm ξ.
Hluav taws xob repulsion yog siv cov nqi repulsion kom muaj kev ruaj ntseg dispersion.
Surfactants tuaj yeem ionize ntau tus nqi tsis zoo (lossis raug them zoo) ions hauv cov tshuaj aqueous, uas ruaj khov adsorbed rau ntawm cov xim xim, kom cov khoom no muaj tib yam nqi, thiab lwm yam ions nrog cov nqi sib txawv dawb diffuse rau hauv cov kua. nruab nrab. Nyob ib ncig ntawm, ib txheej diffusion (hluav taws xob ob txheej) ntawm them ions yog tsim. Qhov muaj peev xwm sib txawv ntawm ob txheej ntawm ions los ntawm cov khoom nto mus rau qhov deb tshaj plaws ntawm cov txheej txheem diffusion (uas yog, qhov twg tus nqi rov qab yog 0) yog hu ua ξ peev xwm. Lub electrostatic repulsion ntawm qhov hais los ntawm qhov no, thiab cov hais nrog tib tus nqi yuav tawm tsam ib leeg thaum lawv tuaj yeem sib cuag, thiaj li ua kom muaj kev ruaj ntseg ntawm cov txheej txheem dispersed, uas yog lub npe nrov DLVO txoj kev xav.
Nyob rau hauv cov ntaub ntawv ntawm hluav taws xob repulsion, lub surfactant yuav tsum muaj siab ionization kev ua tau zoo, thiab anionic surfactants thiab ib co inorganic dielectrics feem ntau yog siv, xws li: tripotassium polyphosphate, potassium pyrophosphate, sodium polyphosphate, alkyl aryl sulfonate Sodium Naphthalene Sulfonate, Sodium Nalfonate. Sodium Polycarboxylate, thiab lwm yam.
3. Steric hindrance effect (los yog entropy effect)
Thaum cov pigment dispersed nyob rau hauv ib tug uas tsis yog-aqueous nruab nrab, muaj peev xwm ntawm cov saum toj no-hais cov tshuaj tiv thaiv ionic yog heev tshem tawm, thiab cov non-ionic surfactant tsis ionized nyob rau hauv dej. Hauv qhov no, cov nyhuv ntawm surfactant hu ua steric hindrance effect lossis entropy effect. Vim hais tias cov surfactant tuaj yeem ua adsorbed rau saum npoo ntawm cov xim pigment los tsim cov txheej txheem monomolecular adsorption, cov txheej txheem tsis zoo no tuaj yeem tiv thaiv kev sib sau ntawm cov khoom, yog li tswj kev ruaj ntseg ntawm cov kab mob dispersion (tseem hu ua kev tiv thaiv colloid lossis micelle) .
Surfactant molecular pawg nyob rau saum npoo ntawm cov xim, raws li qhov concentration ntawm surfactant nce, nws entropy yuav txo qis thiab nws txoj kev txav yuav raug txwv. Qhov ze thiab ntau compressed cov pigment hais yog, qhov ntxiv lawv cov entropy yuav txo qis, uas muaj txiaj ntsig zoo rau kev ruaj ntseg ntawm cov kab mob dispersion.
