Defoamers yog ib qho tseem ceeb additive nyob rau hauv txheej formulations. Txawm li cas los xij, ntsib nrog ntau yam ntawm cov khoom lag luam hauv kev ua lag luam, ntau tus engineers feem ntau tsom rau lawv cov "defoaming power" thaum tsis saib xyuas cov hauv paus ntsiab lus. Kev nkag siab txog cov txheej txheem ntawm kev ua ntawm defoamers pab peb xaiv ntau yam kev xaiv hauv ntau lub tshuab.
I. Qhov xwm thiab stabilizing yam ntawm npuas
Ua Npuas Ncauj yog ib lub kaw lus uas cov pa tawm mus rau hauv cov kua. Hauv coatings, npuas feem ntau yog qhia los ntawm cov txheej txheem xws li nplawm thiab daim ntawv thov. Qhov kev ruaj ntseg ntawm npuas yog nyob ntawm lub zog ntawm cov kua zaj duab xis. Cov kua dej ntshiab tsis zoo li tsim cov foams ruaj khov, tab sis surfactants, resins, thiab lwm yam khoom hauv cov txheej txheem adsorb ntawm cov pa roj -kua sib txuas, txo cov kev sib tshuam ntawm lub ntsej muag thiab tsim cov yeeb yaj kiab ua kua uas cuam tshuam cov npuas coalescence thiab tawg.
II. Lub luag haujlwm tseem ceeb ntawm defoamers: cuam tshuam cov kua yeeb yaj kiab stability
Lub luag haujlwm ntawm defoamers yog cuam tshuam qhov kev ruaj ntseg ntawm cov kua nplaum ua npuas dej. Lawv lub hauv paus mechanism yog:
Tsis tshua muaj qhov nro thiab sib kis ceev: Qhov nro ntawm defoamers yog qis dua li ntawm cov kua nplaum ua npuas dej, yog li lawv tuaj yeem kis tau sai sai rau ntawm cov yeeb yaj kiab ua kua, hloov cov qub qub molecules. Tsim cov ntsiab lus tsis muaj zog: Thaum lub sij hawm sib kis, tus defoamer tshem tawm qee cov kua los ntawm cov kua zaj duab xis, ua rau cov zaj duab xis nyias thiab nws thiaj li tawg. Coalescence thiab ntab: Rau microbubbles (200-300nm), qee cov defoamers tuaj yeem txhawb lawv cov coalescence rau hauv cov npuas loj, ua kom lawv nce mus rau cov kua dej thiab tom qab tawg, yog li tshem tawm cov npuas dej tag.
III. Cov yam ntxwv ntawm Defoamers nrog cov qauv tshuaj sib txawv
Cov qauv tshuaj ntawm tus defoamer txiav txim siab nws cov yam ntxwv ua haujlwm. Cov hom muaj xws li:
Polyether-raws li defoamers: xws li EO-PO block polymers. Cov defoamers no muaj kev sib raug zoo thiab tsis tshua muaj peev xwm ua rau cov pinholes, tab sis lawv lub zog defoaming kuj yog me me, ua rau lawv haum rau cov qauv siv. Qhov sib piv hydrophilic / hydrophobic hauv lawv cov qauv yog kho tau, yog li cuam tshuam rau lawv cov dispersibility thiab defoaming ceev hauv dej. Silicone-raws li defoamers: xws li polydimethylsiloxane emulsions. Silicones muaj qhov nro qis heev, ceev defoaming ceev, thiab ua npuas ncauj ua haujlwm zoo heev. Txawm li cas los xij, qee qhov silicones tuaj yeem txav ntawm qhov kub thiab txias, ua rau muaj teeb meem interlayer adhesion. Yog li ntawd, yuav tsum tau ua tib zoo xaiv nyob rau hauv ci xim tshuab. Tsis yog-silicone polymer{11}}raws li defoamers: muab faib rau cov uas muaj hydrophobic hais thiab cov uas tsis muaj. Cov neeg nqa khoom yog qee lub hnub qub- zoo li cov polymers, acrylates, lossis ncaj- saw hydrocarbon compounds, thiab lwm yam. Cov defoamers no yog silicone-dawb, zam kev pheej hmoo ntawm silicone tsiv teb tsaws, thaum tseem muaj lub zog defoaming zoo. Rau cov kuab tshuaj-raws li txheej, polymer-raws li defoamers feem ntau tsis muaj hydrophobic hais. Txawm li cas los xij, rau dej- xim xim, cov khoom siv hydrophobic feem ntau xav tau vim tias lawv tuaj yeem tawg ua npuas dej, ua tau raws li qhov yuav tsum tau ua ntawm defoaming ntawm feem ntau lub tshuab. Txawm li cas los xij, rau cov tshuab uas xav tau gloss siab heev, lossis hauv inkjet luam ntawv, cov khoom tseem tuaj yeem cuam tshuam gloss lossis ua rau lub taub hau luam ntawv clogging; Nyob rau hauv xws li mob, nws yog qhov zoo tshaj los xaiv ib tug qauv uas tsis muaj hydrophobic hais. Cov roj ntxhia-raws li defoamers: Lawv cov qauv zoo ib yam li cov tsis yog -silicone polymer-raws li defoamers, tshwj tsis yog cov cab kuj yog cov roj ntxhia. Lawv siv qhov tsis sib xws ntawm cov roj ntxhia thiab dej, nrog rau kev rhuav tshem - cov nyhuv ntawm cov khoom, kom defoam. Lawv tsuas yog siv nyob rau hauv architectural coatings thiab inks; lawv yog kev lag luam, tab sis lawv kev sib raug zoo thiab kev ua haujlwm ntev ntev yog txwv.
IV. Structure-Kev Sib Raug Zoo: Nws cuam tshuam li cas rau cov ntawv thov
Compatibility vs. Defoaming Fais Fab: Feem ntau, qhov zoo dua qhov kev sib raug zoo ntawm tus defoamer, qhov tsis muaj zog nws lub zog defoaming. Qhov no yog vim hais tias tag nrho cov molecules tau yooj yim mus sau ntawm lub interface. Yog li ntawd, qhov sib npaug yuav tsum raug ntaus ntawm ob. Molecular Luj: Siab molecular hnyav defoamers feem ntau ruaj khov, tab sis diffuse qeeb dua; Tsawg molecular hnyav defoamers diffuse sai, tab sis tej zaum yuav emulsified los ntawm lub cev thiab ua tsis tau zoo. Tsis yog-Silicone vs. Silicone: Silicone defoamers siv tau nyob rau hauv chav tsev kub, tab sis tej zaum yuav muaj qee yam cuam tshuam rau kev rov ua dua thaum kub kub; non-silicone defoamers yog tshav kub-resistant thiab haum rau ci xim tshuab.
V. Kev Xaiv Cov Ntsiab Cai hauv cov ntawv thov
Tsis muaj ib qho defoamer haum rau txhua lub tshuab. Thaum xaiv ib qho, xav txog cov hauv qab no:
System viscosity: Siab viscosity yuav tsum muaj zog defoaming peev xwm. Zaj duab xis thickness: High film thickness yuav tsum muaj ib tug defoamer muaj peev xwm tuav microbubbles. Gloss yuav tsum tau: High-gloss systems yuav tsum tsis txhob defoamers cuam tshuam gloss. Daim ntawv thov txheej txheem: siab-kev ceev shearing yuav ua rau defoamers ua tsis tau zoo; shear- hom resistant yuav tsum tau xaiv.
