Polyurethane ua npuas ncauj, siv dav siv cov khoom ua npuas ncauj, nws yooj yim rau yellowing lub sij hawm.
Qhov peb hu ua yellowing-resistant ua npuas ncauj tam sim no feem ntau yog hais txog qhov sib ntxiv ntawm cov tshuaj tua kab mob antioxidants, cua sov stabilizers thiab lub teeb stabilizers thaum lub sij hawm foaming ntau lawm, uas tuaj yeem ua rau qeeb qeeb ntawm yellowing ntawm cov npuas.
Tab sis muaj cov kev daws teeb meem zoo ntawm no, yog li thov nyeem rau.
1. Ua rau daj
Yellowing feem ntau tshwm sim vim qhov maj mam oxidation ntawm benzene nplhaib ntawm isocyanate hauv polyurethane ua npuas ncauj. Thiab, cov npuas dej molecular chains muaj cov xim xws li carbonyl, amino, azo, thiab alkene, uas xaiv absorbing thiab emit tej wavelengths ntawm lub teeb. Qhov no ua rau kom muaj qhov yellowing ntawm cov npuas dej.
2. Kev daws teeb meem rau daj
Txoj kev ua tau zoo tshaj plaws yog siv cov tsis daj daj aliphatic ISO rau kev ua npuas dej, xws li IPDI, HDI, thiab HMDI, tsim cov urethane ruaj khov dua.
Txawm hais tias lawv decompose rau hauv aliphatic amines, lawv tsis muaj benzene nplhaib conjugation qauv, uas txhais tau hais tias lawv tsis tsim cov pab pawg xim.
Ntxiv mus, aliphatic amines tsis tshua muaj oxidation, txo qhov tshwm sim ntawm yellowing.