Lub preform ntawm lub raj mis tshuab tshuab kuj tseem hu ua parison, uas yog ua los ntawm PET pellets los ntawm kev txhaj tshuaj molding. Nws xav tau tias kev faib ua feem ntawm cov khoom siv rov ua dua tshiab tsis tuaj yeem siab dua 10%, thiab tus lej rov ua haujlwm tsis tuaj yeem tshaj ob zaug.
Kev npaj ua ntej tom qab txhaj tshuaj molding lossis preform siv tom qab cua sov yuav tsum txias rau ntau dua 48 teev, thiab lub sijhawm khaws cia ntawm kev siv ua ntej yuav tsum tsis pub dhau 6 lub hlis. Cov hnub tsim khoom sib txawv, tshwj xeeb yog preforms nrog lub sijhawm ntev dhau, tsis tuaj yeem sib xyaw, qhov laj thawj tseem ceeb yog Hom khoom siv raw hauv kev npaj ua ntej, kev faib ua feem ntawm cov khoom sib xyaw thib ob thiab qhov kev nyuab siab nyob hauv preform sib txawv. Cov xwm txheej no muaj kev cuam tshuam loj rau txheej txheem molding ntawm lub raj mis tshuab, thiab yuav tsum tau kho raws li qhov xwm txheej tiag tiag. Vim tias tus tsiaj muaj dej nqus tau zoo, yuav tsum tau saib xyuas tshwj xeeb rau cov dej noo-pov thawj thaum khaws cia, thiab nws yuav tsum ua kom dehumidified thiab qhuav ua ntej ua. Qhov ziab qhuav feem ntau yog 150 ～ 180 ℃ rau 4 teev, thiab txhawm rau tiv thaiv cov yas yas los ntawm nqus dej noo dua, nws yuav tsum ua kom kub siab tshaj 140 ℃. Txhawm rau tiv thaiv cov yas los ntawm daj thaum kaw, lub tshuab ziab khaub ncaws yuav tsum tau txias kom txog 100 ℃ yam tsis muaj dehumidification thiab tsuas yog ua kom sov.
Ib qho ntxiv, yog tias cov khoom kub siab dhau, cov ntsia hlau txiav lub zog yog siab dhau, lossis kev sib hloov nrawm dhau thaum lub sijhawm txhaj tshuaj PET, acetaldehyde yuav tsim thiab ua rau acidification. Feem ntau, cov ntsiab lus acetaldehyde ntawm PET lub raj mis tom qab ua haujlwm yuav tsum tsawg dua 3ppm, thiab kev npaj ua ntej yog ua ntej crystallization. Yuav tsum muaj cov ntsiab lus ntawm cov dej noo, feem ntau yog txog 1000 ppm, thiab tsawg kawg 900 ppm lossis ntau dua. Yog li, preform yuav tsum tau muab tso rau ib ntus ua ntej nws tuaj yeem ua kom crystallized tom qab cov ntsiab lus noo noo mus txog qhov xav tau cov ntsiab lus noo.
