Photoinitiator yog cov khoom uas tuaj yeem nqus tau lub zog hluav taws xob thiab tsim cov tshuaj nruab nrab nruab nrab nrog cov peev txheej polymerization los ntawm kev hloov tshuaj. Nws kuj tseem yog lub hauv paus tseem ceeb xav tau los ntawm ib qho kab ke UV tua. Photoinitiators tuaj yeem muab faib ua hom hydrogen abstraction thiab hom tawg; Hydrogen scavenging yam yog bimolecular photoinitiator, uas yuav tsum tau koom tes nrog cov khoom sib xyaw uas muaj cov tshuaj hydrogen (feem ntau hu ua co initiator) los tsim cov dawb radicals los ntawm kev siv tshuaj hydrogen tshem tawm; Cleavage photoinitiator yog ib tus qauv molecule photoinitiator, uas yog decomposed rau hauv cov dawb radicals tom qab laser.
(1) Hydrogen abstraction hom: coj xylenone (BP) ua piv txwv. Thaum siv benzophenone ib leeg, olefin monomers tsis tuaj yeem tsim cov duab hluav taws xob, thiab lawv cov kev xav tau los ua photoinitiators sib txawv. Cov tshuaj tiv thaiv kab mob sib txawv alkyl thiab aryl. Thaum rho tawm hydrogen atoms los ntawm cawv thiab ethers, cov pa tuaj yeem yooj yim tua cov benzophenone zoo siab. Thaum rho tawm hydrogen atoms los ntawm amines, ketones tsim cov kev nyuaj siab nrog amines tam sim tom qab lawv tsim cov xeev zoo siab, uas zam kev hloov pauv lub zog mus rau cov pa oxygen. Yog li ntawd, amine systems tsis yooj yim kom tua tau cov pa. Sib piv nrog cov tshuab cawv cawv, nws tseem txo qhov muaj peev xwm hloov pauv hluav taws xob mus rau monomers. Yog li ntawd, amine system feem ntau yog siv hauv daim ntawv thov. Ntxiv rau benzophenone, hom tshuaj tua kab mob no tseem muaj anthraquinone thiab thioxanthone, xws li 2-isopropyl thioxanthone, uas feem ntau siv hauv UV number case.
(2) Pyrolysis yam: Siv benzoin ethers ua piv txwv, benzoin ether yog ib zaug siv dav tshaj plaws photoinitiator, uas yog tus yam ntxwv ncaj qha decomposition ntawm cov hmoov zoo rau hauv tag nrho cov dawb radicals. Cov dawb radicals tsim tawm tuaj yeem pib monomer polymerization. Benzoin ether muaj lub xeev zoo siab luv lub neej thiab tsis yooj yim los tua cov pa lossis styrene, yog li nws tuaj yeem siv tau rau polymerization ntawm styrene. Txawm li cas los xij, benzoin ether muaj qib sib txawv ntawm cov cua sov ua kom tawg txawm tias tsis muaj lub teeb, thiab kev khaws cia tsis zoo. Feem ntau, yuav tsum tau ntxiv cov stabilizer thiab polymerization. Tam sim no, benzoin ether feem ntau siv.
Cov hauv paus ntsiab lus rau xaiv cov kws yees duab:
a Lub teeb pom kev zoo hauv UV ntau;
b. Zoo txheeb ze ruaj ntseg;
c. Tus nqi qis.
