Daim ntawv thov ntawm fumed silica hauv kev tu ncua txhua hnub
Fumed Silica yog ib hom amorphous silica, uas tau npaj los ntawm hydrolysis ntawm organohalosilane ntawm qhov kub. Lub ntsiab loj qhov loj yog nruab nrab ntawm 7-40 nm, thiab qhov tshwj xeeb saum npoo feem ntau loj dua 100m2 / g. Qhov kev coj dawb huv ntawm cov khoom yog siab heev, thiab cov ntsiab lus silicon tsis tsawg dua 99.8%. Fumed silica tau dhau los ua lag luam txij li xyoo 1940 los. Ob peb lub xyoos dhau los, tsis muaj mob ntsws silica los ntawm kev nqus tau cov kab mob silica. Lub Koom Haum International rau kev tshawb fawb txog kev mob qog nqaij hlav (IARC), tsis muaj pov thawj txaus los ua pov thawj tias cov amorphous hluavtawssilicon oxidemuaj cov carcinogenic effect rau tib neeg lossis tsiaj, thiab kev tshawb fawb suav nrog quartz carcinogens. Ntxiv nrog rau daim ntawv yuam (67/548 / EEC), amorphous silicon yog cov khoom lag luam txaus ntshai.
Vim tias nws zoo nyob ruaj khov, muaj sia muaj zog, tuab thiab lwm yam ntxwv, nws tuaj yeem siv dav hauv lub neej txhua hnub. Hauv tib neeg saib xyuas cov khoom lag luam, fumed silica yog qhov tseem ceeb thiab muaj txiaj ntsig ntxiv, ib qho me me uas tuaj yeem tsim cov txiaj ntsig tseem ceeb. Vim tias muaj ntau pawg hydroxyl nyob rau ntawm fumed silica, qhov sib cuam tshuam ntawm qhov me me kuj muaj zog. Hauv cov kua nruab nrog cev, nws yooj yim rau cov dispersion system ntawm fumed silica sib cuam tshuam nrog kev sib txuam thiab kev tsim cov kab ke sib txuas hauv peb-seem, uas ua rau muaj zog viscosity. Tib lub sijhawm, tus so tuaj yeem tiv thaiv qhov ntws ntawm qhov system. Thaum cov kab peb-ntu sib txuas tau raug rau lub shear kev ntxhov siab, lub kaw lus ntawm cov kua dej ntws tau pov tseg. Thaum shear kev ntxhov siab raug tshem tawm, nws tuaj yeem Ua lub network kuj tseem tuaj yeem ua" gel system" ;.
Yog li ntawd, hauv thixotropic thickening muaj nuj nqi, nws tuaj yeem siv cov tshuaj txhuam hniav, tshuaj pleev thaiv hnub, ntsej muag thiab lwm yam gel lossis tshuaj txhuam cov khoom. Nws qhov ntau npaum li cas yog feem ntau 1 ~ 3%, qee qhov tau siab txog 4 ~ 8%. Hauv cov txheej txheem pearlitic tus ntsia thawv los yog tshuaj txau, fumed silica ua lub luag haujlwm tseem ceeb hauv kev ncua, kom txhua tus tuaj yeem ua kom sib kis tusyees hauv lub system kom tiv thaiv kev sib hais haum thiab txhim kho kev ruaj ntseg ntawm lub system. Hauv cov khoom tu plaub hau, fumed silica yog siv dav. Piv txwv, zawv plaub hau los tiv thaiv cov plhaws muaj cov khoom xyaw ua si xws li zinc sulfide, salicylic acid, zinc sulfate thiab zinc. Feem ntau ntawm cov khoom siv yuav tsum tau tawg thiab muab tshem tawm hauv cov kab ke hauv daim ntawv zoo. Qhov sib ntxiv ntawm fumed silica tuaj yeem ua kom tau raws li qhov yuav tsum tau ua.
Nyob rau hauv oily dej khoom, muaj feem ntau muaj roj zoo nkaus. Ntxiv fumed silica tuaj yeem txo cov roj thiab ua kom zoo siab. Fumed silica tuaj yeem txhim kho qhov kub thiab ruaj khov ntawm pH tus nqi hauv roj. Cov tshuaj pleev thaiv hnub kho nrog fumed silica tsis tuaj yeem tsuas yog txhim kho kev ntxhib los mos ntawm tshuaj pleev thaiv hnub, tab sis kuj txhim kho cov dej tsis kam. Kev muab cov tshuaj feem ntau yog 0.5 ~ 3%. Fumed silica kev kho mob txhim kho lub noo noo tsis kam ntawm thaj ua rau thaj thiab gels, thiab tau txais txiaj ntsig zoo rau cov tawv nqaij pleev, pob muag, roj, tshuaj pleev ib ce, ntxuav hniav dawb qab zib thiab tshuaj pleev thaiv hnub. Nws yog tus yam ntxwv qhov loj me thiab kheej kheej qhov loj, zoo txo kev sib txhuam sab hauv cov roj hmab thiab txhim kho kev tawg. Cov tshuaj lom neeg tsawg tsawg ntawm cov xau tuaj yeem tiv thaiv kev nrawm. Hauv txoj kev tshawb fawb no, kev thov cov pa roj carbon dub tshwj xeeb hauv cov roj hmab ntuj tau kawm, thiab kev thov kev cai lij choj ntawm cov pa roj carbon dub hauv cov roj hmab ntuj tau tham.