プラスチック用の HALS 安定剤の選び方
How HALS Work
HALS contain a 2,2,6,6-tetramethylpiperidine ring system. Under UV exposure, the amine nitrogen forms a nitroxyl radical that scavenges carbon-centred radicals from photo-oxidation. The HALS species is then regenerated — allowing a single molecule to interrupt multiple oxidative events. This catalytic mechanism delivers far better long-term UV protection than stoichiometric absorbers.
Low vs High Molecular Weight HALS
- LMW HALS (300–500 g/mol): Higher mobility, faster initial activity, suitable for thick sections (>3 mm)
- HMW HALS (1000–3000+ g/mol): Lower volatility, better permanence — preferred for thin films, 繊維, automotive exterior, wire/cable
ノーネック
N-alkoxyamine HALS with improved performance in acidic environments. Recommended for formulations with halogenated flame retardants, where conventional HALS are deactivated by acid.
Application Recommendations
- Thin films (<0.5 mm): HMW HALS required
- Agricultural film: Must use pesticide-resistant grade
- Automotive exterior: HMW HALS + UV absorber combination
- Outdoor pipe and profile: 紫外線吸収剤 + HMW HALS system
- Wire and cable: HMW HALS for permanence under long-term exposure
Compatibility Notes
- Conventional HALS are sensitive to acid deactivation by halogenated flame retardants — use NOR-HALS
- Some HALS interact with carbon black at high loadings — confirm in pigmented systems
- Combined UV absorber + HALS system consistently outperforms either alone
Typical Dosage
0.1–1.0% by weight. Confirm through accelerated weathering testing (QUV, Xenon arc) for your target service life.
Contact SUNCHEM
SUNCHEM supplies standard and specialty HALS grades with technical selection support. お問い合わせ for samples and documentation.