Mechanism and Application of Light Stabilizers

Light stabilizer is one of the indispensable main auxiliaries in PVC processing; the amount of PVC light stabilizer used is small but its effect is huge. Using a heat stabilizer in PVC processing ensures that PVC does not degrade easily and remains relatively stable. Common heat stabilizers used in PVC processing include basic lead salt stabilizers, metal soap stabilizers, organotin stabilizers, rare-earth stabilizers and epoxidised compounds, etc.

During processing, the thermal decomposition of PVC has little effect on other properties, mainly affecting the colour of the finished product; adding a light stabilizer can inhibit the initial coloration of the product. When the mass fraction of HCl eliminated reaches 0.1%, the colour of PVC begins to change. Depending on the number of conjugated double bonds formed, PVC shows different colours (yellow, orange, red, brown, black).

If oxygen is present during the thermal decomposition of PVC, colloidal carbon, peroxides, carbonyl and ester compounds will be generated. However, over the long service life of the product, the thermal degradation of PVC has a great impact on material properties; adding a heat stabilizer can delay the degradation time or reduce the degradation degree of PVC.