UV安定剤・HALS

紫外線安定剤は、日光が引き起こす分子鎖切断、チョーキング、黄変からプラスチックを保護する添加剤です。 They work three ways: inorganic screens (titanium dioxide, zinc oxide) reflect and absorb UV, organic UV absorbers convert UV energy to heat, and hindered amine light stabilizers (HALS) scavenge the radicals UV generates. Outdoor-durable polymers usually combine a screen or absorber with a HALS, because each addresses a different step of the same degradation. Treat them as complementary, not interchangeable.

Pigment-grade rutile titanium dioxide is the workhorse opaque UV screen for filled and pigmented plastics; zinc oxide gives a similar inorganic block with more transparency in thin sections. Here is the genuine trade-off: pigmentary titanium dioxide can be photocatalytic and actually accelerate chalking unless you specify a coated rutile grade made for durable exterior use. Specify surface-treated rutile (not anatase) wherever the part sees sunlight, and confirm the grade's weathering data before committing a formulation.

Organic UV absorbers such as octocrylene protect clear and lightly pigmented systems where an opaque screen is not acceptable, but they are consumed over time and perform poorly in thin films. The durable answer for most polyolefins and engineering plastics is a HALS, which keeps working catalytically rather than being used up. Pair an absorber with a HALS for real outdoor service life. Confirm regulatory status for any organic UV absorber in your application and jurisdiction.

• 着色された外装用プラスチックおよび異形押出製品の紫外線遮蔽と耐候保護
• 屋外用途向けポリオレフィンフィルム、繊維、成形品の光安定化
• 自動車、建築、農業用プラスチックにおける色調と光沢の保持
• マスターバッチおよびコンパウンドにおける不透明化とUV保護（二酸化チタン）
• 不透明顔料が使用できない透明系でのUV保護（有機系紫外線吸収剤）

• Titanium dioxide u2014 PubChem
• Zinc oxide u2014 PubChem
• Octocrylene u2014 PubChem
• UV-328の収載 — ストックホルム条約POPs