Question 1

What is the difference between HALS and UV absorbers?

Accepted Answer

UV absorbers (UVA) convert incoming UV radiation into harmless heat before it can damage the polymer; HALS do not absorb UV but instead quench the free radicals and hydroperoxides generated by residual UV that penetrates the UVA layer. UVA efficiency follows Beer-Lambert law — thicker films and higher loadings give better screening; below 0.3–0.5 mm thickness, UVA screening becomes incomplete. HALS operate via a catalytic radical-trapping cycle (the Denisov cycle): the nitroxide radical (>N–O•) formed from the hindered amine intercepts chain-carrying radicals, regenerates itself, and can repeat 10–100 times before being consumed. This catalytic nature means HALS are effective at very low loadings (0.1–0.5%) even where UVA screening is incomplete. In practice, UVA + HALS combinations are used together: UVA reduces the UV dose reaching the polymer bulk, while HALS mops up residual radical damage. Synergy is well documented — a 0.1% UVA + 0.1% HALS combination typically outperforms 0.3% of either alone.

Question 2

Low MW HALS (770/292) vs high MW HALS (944/622) — how do I choose?

Accepted Answer

Low MW HALS (770/292) disperses easily and acts fast — good for thin coatings and PU. High MW oligomeric HALS (944/622) has lower volatility and extractability — essential for polyolefin films requiring 5+ year outdoor service life. HALS-770 (Tinuvin 770 equiv., MW 481) and HALS-292 (Tinuvin 292 equiv., MW 509) are esters of 2,2,6,6-tetramethylpiperidine. Their low MW gives good compatibility and fast diffusion through thin coating films, making them the standard for PU clearcoats (automotive, furniture). However, their vapor pressure is higher and they can volatilize from thick-section polyolefins at processing temperatures (200–250 °C). HALS-944 (MW ~2000–3000, oligomeric piperidine succinate) and HALS-622 (MW ~3100–4000, polysuccinate oligomer) have negligible vapor pressure and resist extraction by water, soap, and solvents — critical for agricultural PE mulch film, greenhouse film, and geotextiles exposed to dew, rain, and soil contact. As a rule of thumb: if service life > 3 years outdoors in polyolefin film, specify high-MW HALS.

Question 3

What is NOR-HALS and when is it required?

Accepted Answer

NOR-HALS (N-alkoxy HALS, e.g. Tinuvin 123 equiv.) tolerates acidic flame retardants, sulfur-containing additives, and the presence of phosphite antioxidants without deactivation — conventional HALS is deactivated in these environments. Conventional HALS contains a tertiary amine nitrogen (>N–H or >N–R). Acidic species in the formulation — such as ammonium polyphosphate (APP) flame retardant, acid-catalyst residues, or HCl from PVC processing — protonate the amine and convert it to the inactive ammonium salt, destroying the radical-trapping activity. NOR-HALS (N-alkoxyamine type) replaces the N–H with N–OR; the alkoxyamine does not undergo acid-base reactions and remains active in acidic environments. NOR-HALS is also compatible with phosphite antioxidants (Irgafos 168 type) without forming stable N-H+O-P complexes that inhibit both additives. Typical applications requiring NOR-HALS: halogen-free FR polypropylene (APP-based), PVC stabilization, acid-catalyzed wood coatings, and transparent PP/PC lenses where phosphite co-stabilizers are used.

Question 4

Why should HALS not be used with certain flame retardants?

Accepted Answer

Halogenated flame retardants (HBCD, DBDPE, TBBPA) release HBr during processing, which protonates the HALS amine and deactivates it. The fix is NOR-HALS or choosing non-halogenated FR systems. The classic incompatibility is between HBCD (hexabromocyclododecane) used in EPS foam or PP textile backing and conventional HALS. At extrusion temperatures, HBCD thermally decomposes releasing HBr, which immediately protonates the HALS secondary amine (>N–H → >N+H₂). The protonated HALS cannot enter the Denisov cycle and provides zero light stabilization. This interaction is often discovered only during accelerated weathering testing, when HBCD-containing samples bleach and crack despite nominal HALS addition. Mitigation options: (1) switch to NOR-HALS 123 or similar; (2) use a phosphite or acid-scavenger (CaCO₃, hydrotalcite) to buffer HBr; (3) replace halogenated FR with APP + synergist. Note that APP itself is also mildly acidic and may partially deactivate conventional HALS — NOR-HALS is still preferred for APP-containing formulations.

Question 5

How is weathering resistance tested? What test standards apply?

Accepted Answer

Standard accelerated weathering uses xenon arc (ISO 4892-2 / ASTM G155) or fluorescent UV (ISO 4892-3 / ASTM G154); QUV-A and QUV-B chambers are common. Property tracked: gloss retention, color ΔE, tensile strength, or elongation retention. Xenon arc weatherometers (ISO 4892-2) simulate the full solar spectrum including UV-A, UV-B, and visible; they use a daylight filter (340 nm reference irradiance 0.35–0.51 W/m²/nm) and cyclic moisture. QUV-A (340 nm peak) replicates outdoor UV-A faithfully and is faster; QUV-B (313 nm) accelerates degradation more but can produce artifacts not seen outdoors. ASTM G154 (QUV) and G155 (xenon) specify standard cycles for coatings (e.g., ASTM D4587: 4 h UV at 60 °C, 4 h condensation at 50 °C). For plastics, ISO 4892-3 Cycle 1 (UV-A 340 nm, 8h UV / 4h condensation) is common. Property endpoints depend on application: automotive OEM typically requires ΔE < 1 and gloss retention > 70% after 2,000 h xenon; agricultural PE film targets ≥ 50% tensile retention after 1,500 h QUV. Request supplier weathering data at matched test conditions to your specification before finalizing the HALS/UVA package.

Question 6

What loading levels of HALS and UVA are typical?

Accepted Answer

HALS: 0.1–0.5% for thin films and coatings; 0.5–1.0% for thick-section polyolefins and high-UV regions. UVA: 0.1–0.3% for thick films; up to 1.0% for thin sections where Beer-Lambert screening is inadequate. Dosage depends strongly on film thickness and expected UV exposure. For a 200-μm agricultural PE mulch film in Southern Europe or Middle East (annual UV dose ~5,000 MJ/m²), a typical formulation is HALS-944 at 0.5–0.8% + UVA-328 at 0.2–0.3%. For a 2-mm polycarbonate sheet, UVA can be reduced to 0.05–0.1% because the Beer-Lambert path length is much longer. For automotive two-coat (basecoat + clearcoat), clearcoat typically contains 0.8–1.2% HALS-292 + 0.2–0.4% UVA-1130 or similar. Over-dosing HALS > 1.5% in thin polyolefin film can cause HALS blooming (surface migration causing haze). Always confirm with a supplier-supported formulation trial at your target thickness and geography.

Question 7

What is the minimum order quantity (MOQ)?

Accepted Answer

Starter orders from 25 kg; standard commercial orders 500 kg; FCL from 1 MT. HALS liquids (292, 123) in 200 kg drums. Solid HALS grades (770, 944, 622, NOR-HALS) and UVA powder grades (328, 327, 1577) are packed in 25 kg kraft bags with PE liner. HALS-292 and HALS-123 are viscous liquids supplied in 200 kg steel drums. For sea freight, most HALS and UVA are classified as non-hazardous (non-DG) if purity ≤ 97%; confirm with the SDS for exact UN classification. Liquid HALS in bulk flexi-tanks (1,000 L) are available for large-volume buyers. Sample policy: 100–500 g free with company letterhead inquiry; courier at buyer's account.

Question 8

What documents are available — COA, MSDS, TDS?

Accepted Answer

COA, SDS/MSDS, and TDS are provided standard; REACH declarations and RoHS compliance letters available on request. HALS COA parameters: purity (GC ≥ 97–99%), melting point (solid grades), viscosity (liquid grades), color (Gardner or APHA), ash content, and specific gravity. UVA COA parameters: purity (GC or HPLC), melting point, UV absorption λmax (measured in ethanol), and color. SDS prepared per GHS Rev. 7 in English and Chinese; available in German, Spanish on request. For EU export, REACH registration status and SVHC absence declarations are available for all commodity HALS/UVA grades. Some specialty grades (NOR-HALS 123 equivalent) are not yet REACH-registered by all Chinese producers — confirm before targeting EU buyers.

Application	Recommended HALS	Recommended UVA	Key Constraint
Outdoor PP/PE film (agri, greenhouse)	HALS 944 (high MW)	UVA-328 or UVA-329	Avoid with HBCD or acidic FR
PU topcoat (automotive, furniture)	HALS 292 (low MW, fast)	UVA-1130 or UVA-329	Check amine compatibility with catalyst
Powder coating (architectural Al)	HALS 292 or powder-grade HALS	UVA-400 (non-migrating)	Grind compatibility — use wax-coated grade
Waterborne basecoat / clearcoat	HALS waterborne (water-dispersible)	UVA-928 (waterborne)	pH 7–9 stability of HALS emulsion
PP geotextile / rope	HALS 944 or 622 (polymeric)	None (HALS alone sufficient)	UVA can sensitize thick PE sections
Clear wood varnish (outdoor)	HALS 292 + 1130 blend	UVA-328 (Tinuvin 328 equiv.)	Migration in oil-based finish — use HMW
Transparent PP/PC lens	NOR-HALS (acid-tolerant)	UVA-triazine-1577	NOR-HALS required if phosphite AO used

BASF / Solvay Brand Grade	China Equivalent	Major Chinese Producers
Tinuvin 770 (BASF)	HALS-770 / UV-770	利安隆 (Lianlong), 天集 (Tianji), 盐城利安 (Yancheng LA)
Tinuvin 292 (BASF)	HALS-292 / LS-292	利安隆, 营口风光 (Yingkou Fengguang), 江苏极易 (Jiyi)
Tinuvin 944 (BASF)	HALS-944 / LS-944	利安隆, 天集, 万泰 (Wantai)
Chimassorb 622 (BASF)	HALS-622 / LS-622	利安隆, 营口风光, 江苏极易
Tinuvin 123 NOR-HALS (BASF)	HALS-123 / NOR-HALS 123	利安隆, 天集 (limited supply)
Tinuvin 328 (BASF)	UV-328 / UVA-328	利安隆, 营口风光, 万泰
Tinuvin 329 (BASF)	UV-329 / UVA-329	利安隆, 天集, 盐城利安
Tinuvin P / UV-327 (BASF)	UV-327 / UVA-327	利安隆, 营口风光, 江苏极易
Tinuvin 99-2 (BASF)	UVA-99 (polymeric BZT)	利安隆, 天集
Cyasorb UV-531 (Solvay)	UV-531 / BP-531	利安隆, 营口风光, 万泰 (most common BZP)
Cyasorb UV-9 / BP-12 (generic)	UV-9 / BP-9 / BZP-9	盐城利安, 天集, 万泰
Tinuvin 1577 Triazine (BASF)	UVA-1577 / Triazine-1577	利安隆 (main), 天集
Tinuvin 400 Triazine (BASF)	UVA-400 / Triazine-400	利安隆, 江苏极易

HALS & UV Stabilizers for Plastics, Coatings & Films

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All Grades (by chemistry class)

HALS — Monomeric (Low MW)(4)

HALS 770 Light Stabilizer

HALS 292 Light Stabilizer

Anti-Yellowing Agent HALS

HALS (Hindered Amine Light Stabilizer)

HALS — Oligomeric / Polymeric (High MW)(5)

HALS 944 Oligomeric

HALS 622 Light Stabilizer

Light Stabilizer 622

Light Stabilizer 944

Hindered Amine Light Stabilizer (High MW)

HALS — Specialty (NOR-HALS, Application-Specific)(5)

NOR-HALS (N-Alkoxy HALS)

HALS 123 Light Stabilizer

HALS for PP

HALS for Powder Coating

HALS for Waterborne Coating

UV Absorbers — Benzotriazole (UVA-BZT)(7)

Benzotriazole UV Absorber

UV Absorber Benzotriazole 328

UV Absorber Benzotriazole 329

UV Absorber 99 (Tinuvin 99)

UV-327 Benzotriazole Stabilizer

UV Absorber 327

UV Absorber 328

UV Absorbers — Benzophenone & Triazine(6)

Benzophenone UV Absorber

UV Absorber Benzophenone-531

UV Absorber Benzophenone-9

UV-531 Benzophenone Stabilizer

UV Absorber Triazine 1577

UV Absorber Triazine 400

Imported Brand → China Equivalent

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