Ultraviolet absorbers tuaj yeem nqus tau lub zog muaj zog ultraviolet rays, hloov mus rau hauv daim ntawv ntawm lub zog, tso lub zog nqus, thiab tom qab ntawd haus nws los ntawm thermal zog lossis tsis muaj hluav taws xob tsis zoo kom tsis txhob muaj kev puas tsuaj ntawm daim tawv nqaij los ntawm ultraviolet rays, thiab tiv thaiv cov photophysical thiab photochemical decomposition tshwm sim ntawm siab molecular polymers vim yog nqus ntawm ultraviolet rays. Tam sim no, feem ntau siv UV absorbers feem ntau suav nrog benzophenones, benzotriazoles, salicylates, hloov acrylonitriles, triazines thiab lwm yam. Muaj qee qhov sib txawv. Shanghai Jingyan Chemical hauv qab no yuav qhia txog cov txheej txheem ntawm kev ua ntawm ntau hom UV absorbers.
1. Benzophenones
Benzophenone UV absorbers yog cov khoom siv dav tshaj plaws ntawm UV absorbers, uas nqus UV-A, UV-B thiab UV-C maj mam. Cov pab pawg ketone thiab pawg hydroxyl hauv cov molecule tuaj yeem tsim ib qho kev sib koom ua ke hydrogen los tsim ib lub nplhaib butyl chelate. Tom qab absorbing ultraviolet lub teeb lub zog, lub molecule undergoes thermal co, lub internal hydrogen daim ntawv cog lus yog tawg, lub nplhaib chelate qhib, thiab lub zog ultraviolet hloov mus rau hauv tshav kub zog thiab tso tawm. Tsis tas li ntawd, pawg carbonyl nyob rau hauv lub molecule yuav zoo siab los ntawm absorbed ultraviolet lub teeb lub zog, uas ua rau kev hloov thiab enol qauv, uas kuj siv ib feem ntawm lub zog. Nyob rau hauv hom UV absorber no, lub zog ntawm intramolecular hydrogen daim ntawv cog lus muaj feem xyuam rau nws lub teeb stabilization nyhuv. Cov nyhuv stabilization ntawm UV absorber kuj muaj feem xyuam rau qhov ntev ntawm alkoxy saw ntawm lub nplhaib benzene. Yog tias qhov ntev yog sib xws nrog cov polymer, cov nyhuv stabilization yog txoj cai. Nyob rau hauv benzophenone UV absorber, lub ortho txoj hauj lwm ntawm cov carbonyl yuav tsum muaj 10 hydroxyl pawg, txwv tsis pub nws yuav tsis tsim intrinsic hydrogen thiab siv tsis tau raws li ib tug UV absorber. Xim, zoo compatibility nrog siab molecular polymers. Yog tias muaj ob pawg hydroxyl nyob rau hauv ortho txoj hauj lwm ntawm pawg carbonyl, nws tuaj yeem nqus tau ultraviolet rays ntawm 300-400 fm, thiab tuaj yeem nqus tau ib feem ntawm lub teeb pom kev. Vim qhov nqus ntawm lub teeb pom kev zoo, lub teeb ntxiv yog tsis sib npaug, thiab cov khoom sib txuas nrog UV absorber no tshwm daj. Lub compatibility nrog siab molecular polymers kuj tsis zoo, yog li nws daim ntawv thov ntau yam me me. Txawm hais tias benzophenone tsis muaj o-hydroxyl pab pawg kuj muaj peev xwm nqus tau cov kab hluav taws xob ultraviolet, nws yuav ua rau nws tus kheej decomposition thaum raug lub teeb, yog li nws tsis haum rau siv los ua ultraviolet absorbers.
2. Salicylate
Salicylate UV absorbers yog thawj zaug siv, thiab salicylates kuj muaj cov khoom siv hydrogen hauv cov molecule. Hom ultraviolet absorber no muaj peev xwm tsis tshua muaj peev xwm nqus tau ultraviolet rays thaum pib, thiab qhov nqus nqus tau nqaim heev (tsawg dua 340vm), tab sis tom qab qee lub sijhawm ntawm ultraviolet irradiation, nws nqus tau maj mam nce mus txog qhov siab tshaj plaws nqus tus nqi, Qhov no yog vim lub rearrangement ntawm molecules nyob rau hauv ultraviolet irradiation. , tsim cov qauv benzophenone nrog lub peev xwm nqus ultraviolet muaj zog, yog li txhim kho nws txoj kev nqus ultraviolet. Yog li ntawd, nws yog hu ua Pioneer UV Absorber. Tom qab dihydroxybenzophenone thiab nws cov derivatives undergo molecular rearrangement, lawv muaj peev xwm nqus tau ib feem ntawm lub teeb pom kev zoo thiab tshwm daj, ua rau yellowing ntawm cov tshuaj ntxiv nrog no ultraviolet absorber.
3. Benzotriazoles
Cov txheej txheem ntawm kev ua ntawm benzotriazole ultraviolet absorbers zoo ib yam li benzophenone. Pom lub teeb saum toj no meters, yog li cov khoom yuav tsis muaj xim;
4. Hloov acrylonitrile thiab triazine
Tsis tas li ntawd, cov hloov pauv acrylonitrile thiab triazine ultraviolet absorbers, raws li cov txheej txheem ntawm kev ua, kuj yog cis-trans isomerization, kom lub zog ntawm lub teeb hloov mus rau hauv lub zog tsis muaj zog thiab tso tawm, thiab ultraviolet absorbers hloov los ntawm acrylonitrile tuaj yeem nqus tau {{ 1}} fm Ultraviolet lub teeb, tsis nqus lub teeb pom kev, thiab yuav tsis ua rau daim ntawv thov dej nyab, thiab ultraviolet absorber tuaj yeem nqus cov noob chromogenic thiab chromogenic pab pawg nrog lub wavelength hauv qab 400-M, uas yog tag nrho txuas nrog lub aromatic core.
5. Lwm chav kawm
Organickel kuj tseem siv tau los ua UV absorber, tab sis feem ntau yog cais raws li quencher, uas muaj peev xwm nqus tau UV teeb dua li yav dhau los, tab sis tiv thaiv kev sib cais ntawm cov polymer nyob ib puag ncig absorbing UV teeb. Lub organonickel polymer reacts nrog cov molecules nyob rau hauv lub polymer uas zoo siab rau lub xeev zoo siab nyob rau hauv ultraviolet lub teeb irradiation, thiaj li hais tias lub xeev zoo siab rov qab mus rau lub xeev zoo siab. Hauv av hauv lub xeev, lub zog ultraviolet hloov mus rau hauv lub zog qis tsis ua rau nws puas tsuaj. Txhawm rau tiv thaiv cov polymer los ntawm kev puas tsuaj, nws yog hu ua quencher vim tias nws cov txheej txheem ntawm kev ua yog txawv ntawm cov UV absorbers. UV absorbers hloov lawv cov qauv molecular, thiab quenchers tsuas yog dissipate zog los ntawm kev hloov hluav taws xob hloov pauv.
Tsis tas li ntawd, carbon dub, titanium dioxide, zinc oxide, zinc barium thiab lwm yam tshuaj pleev thaiv hnub kuj yog ib chav kawm ntawm cov tshuaj uas tuaj yeem nqus tau lossis cuam tshuam txog cov kab hluav taws xob ultraviolet. Ib txheej thaiv txheej yog teem nruab nrab ntawm cov polymer thiab lub teeb qhov chaw kom nqus los yog cuam tshuam cov hluav taws xob ultraviolet. Thaum nws ncav cuag lub polymer nto, Absorbed thiab reflected, tiv thaiv UV teeb los ntawm nkag mus rau hauv lub polymer sab hauv, nrog carbon dub yog qhov zoo tshaj plaws. Dawb radical scavengers kuj yog ib chav kawm ntawm cov khoom uas tuaj yeem tsim lub teeb stabilization, thiab yog piperidine derivatives nrog steric hindrance effect, hu ua hindered amine light stabilizers.
