Effect of Rare Earth Complexes Containing Benzophenone Structure on Light Stability of PVC
Rare earth stabilizers with both thermal and light stability are of great significance for reducing PVC processing costs,improving PVC production efficiency and opening up the application fields of rare earth stabi-lizers.Therefore,the effects of 2,4-dihydroxybenzophenone lanthanum(LBP),2-benzoylbenzoate lanthanum(LBA)and ternary composite stabilizers on the light stability of PVC were studied through artificial accelerated UV aging experiments and outdoor natural light aging experiments.The results show that the weight loss rates of PVC sheets with LBP and LBA(LBP∶ZnSt2∶PE=2∶1∶2,LBA∶ZnSt2∶PE=1∶1∶3)are 2.7％and 6.2％respective-ly after 10 d of artificial UV aging,and the retention rates of tensile strength are 87.6％and 81.8％respectively after 35 d of natural light aging.The composite stabilizer improves the light stability of PVC best.The rare earth stabilizer can absorb the hydrogen chloride produced by PVC degradation,reduce the concentration of hydrogen chloride,so as to weaken the catalytic effect of hydrogen chloride on PVC degradation,inhibit PVC from remov-ing HCl to form double bonds,and prevent the double bonds from forming peroxides to form carbonyl com-pounds under the action of oxygen.
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