HPMC (hydroxypropyl methylcellulose) yog ib qho khoom siv tau zoo heev thiab siv dav hauv kev tsim cov txheej txheem thiab cov xim. Ib qho ntawm nws lub luag haujlwm tseem ceeb yog txhawm rau txhim kho viscosity tswj, uas tsis yog tsuas yog txhim kho rheology ntawm txheej thiab xim, tab sis kuj txhim kho kev tsim kho kev ua haujlwm thiab cov yeeb yaj kiab kawg.
1. Cov khoom tseem ceeb ntawm HPMC
HPMC yog non-ionic cellulose ether nrog dej solubility zoo thiab organic solvent solubility. Nws tuaj yeem yaj thiab tsim cov tshuaj colloidal ruaj khov ntawm qhov sib txawv ntawm qhov kub thiab txias pH. Lub luag haujlwm tseem ceeb ntawm kev ua ntawm HPMC yog tsim kom muaj cov qauv sib txuas los ntawm kev sib txuas lus hydrogen thiab van der Waals rog, yog li cuam tshuam rau cov khoom rheological ntawm cov coatings lossis xim. Nws cov viscosity hloov pauv nrog kev hloov pauv hauv cov concentration, kub, shear npaum li cas thiab lwm yam, uas ua rau nws daim ntawv thov nyob rau hauv coatings thiab xim muaj ib tug loj hloov chaw.
2. Kev ua haujlwm ntawm HPMC hauv cov txheej txheem thiab xim
Kev hloov kho viscosity: Lub luag haujlwm tseem ceeb ntawm HPMC yog kho cov viscosity ntawm lub kaw lus. Hauv coatings thiab xim, viscosity yog qhov tseem ceeb uas cuam tshuam ncaj qha rau kev tsim kho, theem, thiab cov yeeb yaj kiab kawg ntawm cov khoom. HPMC tuaj yeem tswj cov viscosity ntawm cov txheej txheem los ntawm kev hloov cov qauv molecular lossis concentration, ua kom ruaj khov thiab ua haujlwm ntawm cov txheej thaum khaws cia, kev thauj mus los thiab kev tsim kho.
Rheological tswj: HPMC muab cov txheej los yog pleev xim zoo rheological zog, kom nws tuav lub siab viscosity thaum zoo li qub los tiv thaiv sedimentation, thiab tuaj yeem txo cov viscosity hauv shearing, ua rau nws yooj yim rau kev thov. Qhov thixotropy no yog qhov tseem ceeb rau kev tsim kho ntawm cov txheej txheem thiab cov xim, tshwj xeeb tshaj yog thaum txau, txhuam los yog dov, uas yuav pab kom ua tiav cov txheej txheem zoo thiab du.
Anti-sagging kev ua tau zoo: Thaum cov coatings los yog pleev xim rau ntawm qhov chaw ntsug, sagging feem ntau tshwm sim, uas yog, txheej ntws nyob rau hauv qhov kev txiav txim ntawm lub ntiajteb txawj nqus, uas ua rau cov zaj duab xis tuab thiab txawm ntws. HPMC muaj txiaj ntsig zoo tiv thaiv qhov tshwm sim sagging los ntawm kev txhim kho cov viscosity thiab thixotropy ntawm lub cev, ua kom muaj kev ruaj ntseg ntawm txheej thaum siv rau ntawm qhov chaw ntsug.
Anti-sedimentation nyhuv: Nyob rau hauv cov txheej txheem nrog ntau pigments los yog fillers, pigments los yog fillers yog nquag mus rau sedimentation, cuam tshuam lub uniformity ntawm txheej. HPMC slows down lub sedimentation tus nqi ntawm cov khoom hais los ntawm kev ua kom lub viscosity ntawm lub system. Nyob rau tib lub sijhawm, nws tuav nws txoj kev ncua hauv cov xim los ntawm kev cuam tshuam nrog cov xim xim, kom ntseeg tau tias cov xim zoo ib yam thiab zoo ib yam thaum lub sijhawm tsim kho.
Txhim kho kev ruaj ntseg cia: Thaum lub sij hawm ntev cia, cov xim yog nquag mus rau stratification, coagulation los yog sedimentation. Qhov sib ntxiv ntawm HPMC tuaj yeem txhim kho kev ruaj ntseg ntawm cov xim, tswj qhov sib xws thiab viscosity ntawm cov xim, yog li txuas nws lub neej txee thiab zam cov khoom lag luam degradation los ntawm kev cia tsis raug.
3. Cov yam ntxwv cuam tshuam rau viscosity tswj los ntawm HPMC
Concentration: Qhov concentration ntawm HPMC yog qhov ncaj qha cuam tshuam rau viscosity ntawm cov xim lossis xim. Raws li qhov concentration ntawm HPMC nce, viscosity ntawm lub kaw lus yuav nce ntau. Rau cov txheej txheem uas xav tau viscosity siab dua, tsim nyog nce tus nqi ntawm HPMC tuaj yeem ua tiav qib viscosity zoo tagnrho. Txawm li cas los xij, qhov concentration siab dhau kuj tuaj yeem ua rau lub cev muaj kuab heev thiab cuam tshuam rau kev tsim kho. Yog li ntawd, nws yog ib qho tsim nyog yuav tsum tswj hwm tus nqi ntawm HPMC ntxiv raws li kev thov tshwj xeeb scenario thiab kev tsim kho.
Molecular Luj: Qhov hnyav molecular ntawm HPMC kuj yog ib qho tseem ceeb cuam tshuam rau viscosity. HPMC nrog siab molecular hnyav ua ib tug denser network qauv nyob rau hauv cov kev daws, uas yuav ho nce lub viscosity ntawm txheej; Thaum HPMC nrog qhov hnyav molecular qis pom muaj qis viscosity. Los ntawm kev xaiv HPMC nrog qhov sib txawv molecular hnyav, lub viscosity ntawm cov txheej los yog xim tuaj yeem hloov kho kom tau raws li kev tsim kho sib txawv.
Kub: Lub viscosity ntawm HPMC txo nrog nce kub. Yog li ntawd, thaum tsim kho nyob rau hauv ib qho chaw kub kub, nws yog ib qho tsim nyog yuav tau xaiv HPMC ntau yam uas muaj qhov kub thiab txias zoo dua los yog tsim kom muaj kev siv tshuaj ntxiv kom ntseeg tau tias kev tsim kho thiab kev ua yeeb yaj kiab zoo ntawm cov txheej txheem nyob rau hauv qhov kub thiab txias.
pH tus nqi: HPMC ruaj khov nyob rau hauv ntau pH ntau, tab sis huab cua acid thiab alkali tej yam kev mob yuav cuam tshuam rau nws viscosity stability. Hauv ib puag ncig acid lossis alkali muaj zog, HPMC tuaj yeem degrade lossis ua tsis tiav, ua rau txo qis viscosity. Yog li ntawd, thaum tsim cov qauv, xyuas kom meej tias pH tus nqi ntawm lub system yog nruab nrab los tswj cov viscosity tswj cov nyhuv ntawm HPMC.
Shear npaum li cas: HPMC yog shear-thinning thickener, uas yog, nws cov viscosity yuav raug txo kom tsawg ntawm cov shear siab. Cov cuab yeej no tseem ceeb heev hauv cov txheej txheem tsim kho, vim tias thaum txhuam, dov lossis txau, cov txheej txheem yog raug rau lub zog shear loj, thiab HPMC tuaj yeem txhim kho kev tsim kho los ntawm kev txo cov viscosity. Tom qab kev tsim kho tiav lawm, lub zog shear yuav ploj mus, thiab HPMC tuaj yeem kho cov viscosity ntawm cov txheej txheem kom ntseeg tau tias qhov sib xws thiab tuab ntawm cov zaj duab xis txheej.
4. Kev siv HPMC hauv cov txheej txheem sib txawv
Water-based coatings: HPMC yog siv dav hauv cov txheej txheem dej. Nws tuaj yeem tsis tsuas yog siv los ua cov thickener, tab sis kuj yog ib qho kev pab ua zaj duab xis thiab stabilizer. Hauv cov txheej txheem dej, HPMC tuaj yeem ua kom cov viscosity ntawm txheej txheej, txhim kho nws cov rheology thiab leveling, thiab tiv thaiv sedimentation thiab sagging. Nyob rau tib lub sijhawm, nws tseem tuaj yeem txhim kho cov dej tsis kam thiab txhuam tsis kam ntawm cov zaj duab xis txheej thiab txuas ntxiv lub neej kev pab cuam ntawm txheej.
Solvent-based coatings: Txawm hais tias HPMC kuj siv tsawg dua hauv cov txheej txheem hnyav, nws tseem tuaj yeem siv los ua cov thickener thiab qib pab. Tshwj xeeb tshaj yog nyob rau hauv uas tsis tshua muaj volatile organic compounds (VOC) coatings, HPMC muaj peev xwm muab qhov tsim nyog viscosity tswj thiab rheology hloov, yog li txo cov kev siv cov kuab tshuaj thiab ua tau raws li ib puag ncig tiv thaiv cov cai.
Powder coatings: Hauv cov hmoov txheej, HPMC tuaj yeem siv los ua cov ntawv khi thiab cov thickener los txhim kho cov dej ntws thiab cov yeeb yaj kiab tsim los ntawm kev ua kom cov viscosity ntawm cov hmoov. HPMC tuaj yeem ua kom ntseeg tau tias cov hmoov txheej tsis yooj yim rau ya thaum lub sijhawm tsim kho, thaum txhim kho qhov sib xws thiab qhov ntom ntom ntawm cov zaj duab xis txheej.
HPMC ua tau zoo heev viscosity tswj nyob rau hauv coatings thiab xim los ntawm nws cov cim lub cev thiab tshuaj. Nws tuaj yeem tsis tsuas yog kho cov viscosity ntawm lub cev, tab sis kuj txhim kho cov txheej txheem rheology, txhim kho cov khoom tiv thaiv sagging thiab tiv thaiv kev daws teeb meem, thiab txhim kho kev ruaj ntseg cia. Raws li cov txheej txheem sib txawv thiab kev tsim kho, los ntawm kev kho qhov concentration, molecular yuag, kub, pH tus nqi thiab lwm yam ntawm HPMC, viscosity tuaj yeem tswj tau zoo, yog li txhim kho kev tsim kho ntawm cov txheej txheem thiab cov txheej txheem kawg.
Post lub sij hawm: Sep-14-2024