1. The mechanism of action of UV resistant additives
Ultraviolet absorption
Absorbents (such as benzophenones and benzotriazoles) can convert ultraviolet rays into harmless heat energy for release.
For example, Sumisorb series products from Sumitomo Chemical in Japan can effectively absorb ultraviolet rays ranging from 280 to 400nm.
Free radical trapping
Hindered amine light stabilizers (HALS) can capture free radicals induced by ultraviolet light and inhibit chain degradation reactions.
Example: BASF Tinuvin 770 enhances anti-aging effect by chelating metal ions.
Light shielding
Inorganic fillers such as carbon black and zinc oxide can physically block ultraviolet rays from penetrating materials.
Example: The high-dispersed carbon black masterbatch from Japan's JSR Corporation is used in HDPE pipes, improving shielding efficiency by 30%.
II. Positive impacts on plastic products
Extend outdoor lifespan
The test showed that the tensile strength of PP board without added UV stabilizer decreased by 50% after being exposed to sunlight in Hainan for one year, while the lifespan can be extended to 5-8 years with the addition of HALS.
Maintain appearance and performance
Fading prevention: After adding UV stabilizers to ASA resin (such as the Sekisui EXL series from Japan) for automotive bumpers, the ΔE color difference is less than 2 (with an industrial standard of ≤3).
Inhibiting powdering: After adding a light stabilizer to LDPE used in agricultural films, the haze only increased by 5% after 500 hours of xenon lamp aging test.
Maintain mechanical properties
Experimental data: After adding 0.3% benzotriazole absorber to ABS, the impact strength retention rate increased from 35% to 78% after 3000 hours of aging.
III. Potential negative impacts
Processing compatibility
Some additives are prone to decompose during high-temperature extrusion (such as certain organic amines), necessitating the control of processing temperature at or below 240℃.
cost increase
The price of high-end HALS additives can reach 3-5 times that of ordinary UV absorbers, resulting in an 8-15% increase in material costs.
environmental impact
Some organic additives pose a migration risk, and the EU REACH regulation restricts the use concentration of certain benzotriazole substances.
