Dab tsi yog vim li cas rau yellowing ntawm PVC yas?

Dab tsi yog vim li cas rau yellowing ntawm PVC yas?

Lub yellowing ntawm plastics yog hais txog cov saw hlau ntawm cov saw hlau zoo li polymer molecular saw tawg nyob rau hauv qhov kub thiab txias, oxidizing ib puag ncig, los yog nyob rau hauv qhov kev txiav txim ntawm ultraviolet, infrared, thiab kab mob, uas ua rau dawb radical detachment.

Kev yellowing ntawm plastics feem ntau suav nrog cov hauv qab no:

1. Ultraviolet hluav taws xob

Lub teeb irradiated los ntawm lub hnub mus rau txheej huab cua sab nrauv yog ib qho spectrum txuas ntxiv nrog lub wavelength ntawm 0.7-3000nm, ntawm 300-400nm ultraviolet hluav taws xob yog lub ntsiab ua rau polymer degradation. Thiab lub zog ntawm photons nyob rau hauv ultraviolet ntau yam ntawm 290-400nm yog 300-419kJ / E, uas yog siab tshaj lub zog ntawm daim ntawv cog lus ntawm ib co raug tshuaj bonds nyob rau hauv polymers.

2. Kev cuam tshuam ntawm cov cua sov stabilizer

Qhov sib txawv ntawm cov cua sov stabilizers muaj qhov sib txawv ntawm lub teeb ruaj khov ntawm PVC.

Ba / Cd thiab organotin carboxylate tebchaw (xws li txiv neej anhydride ester organotin stabilizers) tuaj yeem muab qee qhov kev ruaj ntseg ntawm UV rau PVC profiles siv sab nraum zoov, thaum sulfur-muaj organotin tebchaw (xws li sulfur Alcohol organic tin stabilizers) muab kev ruaj ntseg teeb. Lub teeb ruaj khov ntawm di- ntsev lead stabilizer yog siab dua li ntawm tri- ntsev lead stabilizer.

3. Cov tshuaj tiv thaiv kab mob antioxidant

Tam sim no, cov stabilizers siv los ntawm PVC profile manufacturers feem ntau yog cov stabilizers. Ntxiv nrog rau cov ntsiab lus tseem ceeb uas txhim kho qhov degradation ntawm PVC, lawv kuj muaj xws li lubricating systems, antioxidant systems thiab lwm yam stabilizing systems.

Cov kab mob antioxidant tuaj yeem suav nrog phenolic stabilizers thiab phosphite co-stabilizers. Cov tebchaw no tuaj yeem muaj cov organic impurities yooj yim discolored, thiab ntxiv rau, lawv tuaj yeem ua rau muaj kev cuam tshuam cov xim nyob rau hauv qhov kev txiav txim ntawm lub teeb, oxygen, thiab dej.