UV Stabilizers for Plastics: 5 Types, Mechanisms, Dosage and Selection

UV stabilizers for plastics are additives that slow the photo-oxidation of a polymer in sunlight; the 5 types (HALS, UV absorbers, hindered benzoates, UV screeners and nickel quenchers) are usually compounded at 0.05-1.4 wt% of the polymer. About 70 % of all light stabilizers go into polyolefins such as polypropylene and polyethylene, so which type protects which plastic, and at what level?

Light stabilizers account for about 1 % of global plastic additive consumption by weight, yet they decide how long an outdoor part keeps its properties. Loadings run from 0.05 wt% in a thick polyolefin moulding to 10 wt% of the finished product in a co-extruded cap layer, a 200-fold span that no other stabilizer family covers. UV stabilizers are one of the 43 families of plastic additives and belong to the stabilizer group together with antioxidants and PVC heat stabilizers.

This reference defines the UV stabilizer and the light stabilizer as one entity, explains why sunlight breaks polymer chains, sets out the 4 protection mechanisms and the 5 stabilizer types, compares HALS against UV absorbers criterion by criterion, matches a stabilizer system to each of 11 polymers, gives dosage in wt% with its source, covers interactions with antioxidants and flame retardants, lists the weathering standards, tracks the benzotriazole regulations from the 2014 SVHC listings to the UV-328 POP limits of 2029, names the producers and their trade names, and closes with the complete list of 44 UV stabilizer substances.

The table below compares the 5 types on mechanism, UV absorption, thickness dependence, typical level, uses, example grades and regulatory status.

Typical levels are supplier TDS ranges (BASF, Mayzo) and the EN 12201-1 / ISO 4427-1 pipe value; the qualitative columns summarise the mechanisms described below.

What Is a UV Stabilizer for Plastics?#

A UV stabilizer for plastics, also called a light stabilizer, is an additive that slows the photo-oxidative degradation of a polymer under sunlight or artificial UV light, so the part keeps its strength, colour and gloss outdoors. Light stabilizer is the umbrella term in the BASF and Syensqo catalogues; UV inhibitor, UV additive and the British spelling UV stabiliser name the same products in converter specifications. How many light stabilizers are in commercial use? The plastic additives mapping exercise of the European Chemicals Agency lists 16 light stabilisers registered above 100 tonnes a year, used at typical concentrations of 0.0015 to 6.0 wt% of the polymer.

A UV stabilizer rarely works alone. Phenolic antioxidants and hydroperoxide decomposers, mainly phosphites and thioethers, act as supporting co-stabilizers: they protect the melt during extrusion and moulding, where light stabilizers contribute little, and they remove the hydroperoxides that sunlight later splits into radicals. The UV stabilizer itself is chosen for service life, not for processing stability.

What does "UV stabilized" mean, and is it the same as UV resistant?#

"UV stabilized" means that a plastic contains UV stabilizers, while "UV resistant" describes how well a material resists sunlight, with or without additives; a UV-stabilized polypropylene is resistant only because of its HALS. The two terms describe different things: one is a formulation statement about what was added, the other is a performance statement about the finished material.

Inherent resistance varies by polymer chemistry. PMMA is inherently UV-stable and carries UV absorbers mainly to protect the substrate or the contents behind it, and ASA reaches about 10 times the weathering resistance of ABS because its acrylate rubber phase contains no carbon-carbon double bonds for oxygen to attack. Which polymers resist sunlight without additives, and which collapse within a season, is covered under UV-resistant plastics.

Why Do Plastics Degrade in Sunlight and Need UV Stabilizers?#

Plastics need UV stabilizers because sunlight that reaches the ground (wavelengths above 280-290 nm) excites impurities and chromophores in the polymer and starts a radical chain reaction with oxygen that breaks polymer chains. Pure aliphatic polyolefins absorb only below about 250 nm, so the initiation never comes from the polymer backbone itself. It comes from hydroperoxides, carbonyl groups, titanium and iron catalyst residues and polymer-oxygen charge-transfer complexes left by polymerisation and processing.

Temperature often matters more than the UV dose, because the propagation and decomposition steps follow Arrhenius kinetics and accelerate with every degree of surface heating. Photo-oxidation is therefore one route of polymer degradation, and heat, oxygen and light are compared as causes of polymer degradation in their own section of this reference.

How does sunlight degrade plastics?#

Sunlight degrades plastics through photo-oxidation: UV light splits hydroperoxides and carbonyl groups into radicals, the radicals react with oxygen and the polymer, and the chain reaction cuts or crosslinks polymer chains. The photo-oxidation cycle runs in 4 steps.

1. Alkyl radicals (R•) formed at an initiation site add molecular oxygen and become peroxy radicals: R• + O2 gives ROO•.
2. Peroxy radicals (ROO•) abstract a hydrogen atom from the polymer, which yields a hydroperoxide and a fresh alkyl radical: ROO• + RH gives ROOH + R•.
3. Hydroperoxides (ROOH) absorb UV light and split homolytically into an alkoxy radical and a hydroxyl radical: ROOH + hν gives RO• + •OH.
4. Alkoxy radicals (RO•) undergo β-scission, which cuts the polymer chain and leaves a ketone plus a macroradical that re-enters step 1.

The ketones formed in step 4 are themselves chromophores: they absorb UV and undergo Norrish type II scission at ambient temperature, so the damage compounds. Polycarbonate, aromatic polyesters and polyurethanes follow a different first step, the photo-Fries rearrangement of their aromatic ester and carbonate bonds, which produces coloured hydroxylated species before the radical cycle takes over. The chemistry polymer by polymer is set out on photodegradation of plastics.

Which plastics are most sensitive to UV light?#

Polypropylene is the most light-sensitive commodity plastic because every second backbone carbon carries a tertiary C-H bond, while PMMA and ASA are inherently weather-resistant and need UV absorbers mainly to protect what lies behind them. Polypropylene also takes the highest HALS loadings of any commodity polymer, and it responds to photo-oxidation by chain scission, so its melt flow rate rises as it ages. Polyethylene behaves in the opposite way and crosslinks. The table below pairs each polymer with the reason it degrades and the stabilizer route that answers it.

What are the signs of UV degradation in plastics?#

UV-degraded plastics show 7 typical signs: chalking, surface crazing, gloss loss, yellowing, colour change, embrittlement and loss of elongation. The 7 signs are listed below in the order in which a weathered part usually reveals them.

• Chalking, a loose pigment-rich powder on the surface after the binder polymer has eroded.
• Crazing, a network of fine surface cracks that scatter light.
• Gloss loss, measured as a drop in specular reflectance.
• Yellowing, reported as yellowness index.
• Colour change against the unexposed reference, reported as a colour difference.
• Embrittlement, with impact strength falling before any visible change.
• Loss of elongation at break, the most sensitive mechanical indicator in films and tapes.

Two instrumental signals precede all of these. Melt flow rate rises in polypropylene as chains are cut, and carbonyl groups accumulate in the infrared spectrum, which is the basis of the carbonyl index measured by FTIR. Non-UV causes of colour change such as gas fading and pinking are explained under why plastics turn yellow.

How Do UV Stabilizers Work? 4 Protection Mechanisms#

UV stabilizers work through 4 mechanisms: they absorb UV light and release it as heat, screen or scatter UV at the surface, quench excited molecules before they react, or trap the free radicals that photo-oxidation produces. The 4 mechanisms and the stabilizer classes that use them are listed below.

1. Absorption. UV absorbers such as the benzotriazole UV-326 (Tinuvin 326) and the hydroxyphenyl triazine Tinuvin 1577 take up the photon and dissipate its energy as heat through an excited-state intramolecular proton transfer, returning unchanged to the ground state.
2. Screening. Pigment-grade screeners, namely carbon black, rutile titanium dioxide and zinc oxide, absorb and scatter UV in the outermost layer of the part, so less light reaches the polymer beneath.
3. Quenching. Nickel quenchers such as UV-1084 accept energy from excited carbonyl groups and from singlet oxygen by Förster transfer and release it as heat, which deactivates the excited species before it fragments.
4. Radical trapping. Hindered amine light stabilizers such as Chimassorb 944, Tinuvin 622 and Tinuvin 770 scavenge the alkyl and peroxy radicals of the propagation cycle through the regenerative Denisov cycle, and hindered benzoates such as Cyasorb UV-2908 scavenge radicals as well.

J. Crawford described the proton-transfer mechanism of the benzotriazole absorbers in Progress in Polymer Science in 1999, and the same photophysics sets each absorber class apart: benzotriazoles cover 300-400 nm, the hydroxyphenyl triazine Tinuvin 1577 covers 280-350 nm, oxanilides absorb most strongly in the UV-B region, and cyanoacrylates dissipate the absorbed energy by E/Z isomerisation instead of proton transfer. None of these mechanisms replaces the melt-stabilizing package. Phenolic antioxidants and hydroperoxide decomposers remain in the formulation because they remove the hydroperoxides that would otherwise feed step 3 of the photo-oxidation cycle.

5 Types of UV Stabilizers for Plastics#

The 5 types of UV stabilizers for plastics are hindered amine light stabilizers (HALS), UV absorbers, hindered benzoates, UV screeners such as carbon black, and nickel quenchers; HALS and UV absorbers do most of the work. The UV absorbers divide further into 6 chemical classes: benzotriazoles, 2-hydroxybenzophenones, hydroxyphenyl triazines, oxanilides, cyanoacrylates and benzoxazinones. HALS divide by the substituent on the piperidine nitrogen into N-H, N-alkyl and N-OR (NOR) grades. MarketsandMarkets reports the market in 3 segments, HALS, UV absorbers and quenchers, which matches the same ranking by industrial weight.

1. Hindered amine light stabilizers (HALS)#

Hindered amine light stabilizers (HALS) are 2,2,6,6-tetramethylpiperidine derivatives that trap the radicals of photo-oxidation and regenerate themselves in the Denisov cycle, so they protect plastics for years at 0.05-1 wt% while absorbing almost no UV. In that cycle the amine is first oxidised to an aminoxyl (nitroxyl) radical, the aminoxyl traps an alkyl radical to give an aminoether, and the aminoether then reacts with a peroxy radical and returns the aminoxyl. The four methyl groups around the nitrogen block the side reactions that would otherwise consume the piperidine ring.

E. T. Denisov set out this regenerative cycle in Polymer Degradation and Stability in 1991, Jennifer Hodgson and Michelle Coote at the Australian National University clarified its individual steps in Macromolecules in 2010, and Pieter Gijsman reviewed the mechanism and the limits of its applicability in Polymer Degradation and Stability in 2017. Regeneration is what makes HALS efficient at 0.05 to 1 wt%, because a single molecule intercepts radical after radical instead of being consumed once. Protection is also independent of part thickness, which no UV absorber can claim. The one weakness is the melt: HALS are less effective than phenolic antioxidants during processing, so they never replace the processing stabilizer. Conventional N-H and N-methyl HALS are also largely ineffective in PVC, where hydrogen chloride from dehydrochlorination protonates the piperidine nitrogen, as Capocci and Hubbard described in the Journal of Vinyl and Additive Technology in 2005.

Food-contact status differs sharply between grades. Chimassorb 944 carries a specific migration limit of 3 mg/kg under Regulation (EU) No 10/2011 (FCM 740) and a content cap of 0.3 wt% in polypropylene under 21 CFR 178.2010, while Tinuvin 770 is not in Annex I of EU 10/2011 at all and is cleared in the United States only for adhesives.

Monomeric vs oligomeric HALS#

Monomeric HALS such as Tinuvin 770 (480.7 g/mol) move quickly to the surface of thick parts, while oligomeric HALS such as Chimassorb 944 (Mn 2,000-3,100 g/mol) stay in thin films, fibres and tapes without evaporating or washing out. Mobility and permanence pull in opposite directions, and the table below shows how the industry splits the difference.

Blends exist because the two behaviours are complementary rather than interchangeable: the monomeric component reaches the exposed surface, the oligomeric component stays in the bulk for the life of the part.

NOR HALS and HALS basicity#

NOR HALS are aminoether HALS with a pKb of about 8-10, 4-5 units less basic than N-H HALS, so they keep working in plastics that contain acids from PVC, halogenated flame retardants or sulfur pesticides. Basicity follows the substituent on the piperidine nitrogen, as the scale below shows.

Acids protonate the basic nitrogen and take the stabilizer out of the cycle, which is why greenhouse film is the classic NOR application. Raising the sulfur residue on a greenhouse film from about 1,000 to 2,000 ppm cut film life by 20 to 25 %, as reported at the AMI Agricultural Films conference in 2010, and Tinuvin NOR 371 is dosed at 0.2-1.6 wt% in that application. Grades and agricultural uses of NOR HALS are compared on their own page.

2. UV absorbers (UVA)#

UV absorbers are aromatic molecules that absorb UV light and convert it into heat through an intramolecular proton transfer; because they follow the Beer-Lambert law, their protection grows with concentration and part thickness. Six chemical classes are in commercial use, and they differ in absorption window, thermal stability and food-contact status rather than in mechanism. The table below lists them in the order used throughout this reference.

Absorption ranges are supplier data (Mayzo).

The Beer-Lambert law sets the practical limit of this class. Protection is proportional to concentration multiplied by path length, so a UV absorber cannot protect the outermost micrometres of a thick part, and it cannot protect a thin film at all at normal loadings. That is why benzotriazoles sit at 0.1-0.5 wt% in general plastics and only reach 5-10 wt% in co-extruded cap layers, where a thin, heavily loaded skin shields the bulk below it. Tinuvin 360 and Tinuvin 1577 are formulated for exactly this route and allow direct two-layer co-extrusion of sheet according to the BASF technical data sheets.

Durability differs within the class. Benzophenones show lower long-term photo-permanence, which BASF describes as moderate durability, and they are positioned accordingly in film rather than in long-life mouldings. Regulation has reshaped the class as well: UV-328, UV-327, UV-320 and UV-350 have been replaced in Europe by UV-234, UV-360, the hydroxyphenyl triazines and the cyanoacrylates, and UV-326 and UV-329 are next in line after their 2024 SVHC listing.

Which UV absorber suits which processing temperature?#

The processing temperature decides the UV absorber: UV-P loses 1 % of its weight at 153 °C, while Tinuvin 1577 and UV-360 hold out to 300 °C and 333 °C, which is why only the heavier absorbers suit polycarbonate and PET. The values below are thermogravimetric 1 % weight-loss temperatures measured at 20 °C/min in air.

PET, PBT and PEN are processed at 270-300 °C, so their absorber shortlist narrows to Tinuvin 1577, Tinuvin 1600, UV-234, Uvinul 3030 and Cyasorb UV-3638.

3. Hindered benzoates#

Hindered benzoates such as Cyasorb UV-2908 and UV-120 are HALS synergists for thick polyolefin parts: they scavenge radicals and, under light, rearrange into benzophenone-type UV absorbers. The rearrangement is a photo-Fries reaction, so the benzoate builds its own absorber population during service rather than starting with one. Suppliers position the class for thick-section polypropylene and thermoplastic polyolefin, where Cyasorb UV-2908 is used at 0.1-0.5 wt% alongside a HALS.

Both grades are in Regulation (EU) No 10/2011 with no specific migration limit, Cyasorb UV-2908 as FCM 721 and UV-120 as FCM 480, so only the overall migration limit applies. In the United States, 21 CFR 178.2010 caps Cyasorb UV-2908 at 0.5 wt% in olefin polymers and UV-120 at 0.6 wt% in polypropylene. These are legal maxima, not recommended dosages, and no independent dosage range for UV-120 is established.

4. UV screeners: carbon black, titanium dioxide and zinc oxide#

Carbon black is the most effective UV screener for polyolefins: it absorbs UV in the outer layer of the part, which is why polyethylene pressure pipe carries 2.0-2.5 wt% of it. EN 12201-1 and ISO 4427-1 fix that level together with a primary particle size of 10-25 nm, because dispersion quality matters as much as loading. Grades and particle sizes are covered on carbon black in plastics.

In food contact, carbon black is FCM 411 in Regulation (EU) No 10/2011 with a maximum use level of 2.5 % w/w in the polymer. Colour also changes the thermal history of the part: white pigmented plastics run typically 10-15 °C cooler outdoors than black ones according to Ampacet, and since photo-oxidation follows Arrhenius kinetics, that temperature difference partly offsets the weaker screening of a white pigment.

Rutile titanium dioxide and zinc oxide both absorb and scatter UV, and rutile weathering grades are compared on titanium dioxide in plastics. Pigments are not automatically protective, however. Copper phthalocyanine absorbs UV strongly but its excited state can act as a photoinitiator, and low-surface-treated titanium dioxide can promote the pinking of white polyethylene and polypropylene by over-oxidising the phenolic antioxidant to quinones.

5. Nickel quenchers#

Nickel quenchers such as UV-1084 deactivate excited molecules and singlet oxygen by energy transfer, but their nickel content keeps them to a minor role, mainly in agricultural mulch film. UV-1084 is a nickel(II) thiobisphenolate complex with CAS 14516-71-3, and it is covered by the REACH Annex XVII group entry for nickel and its compounds in articles with direct and prolonged skin contact. It is not listed in Annex I of Regulation (EU) No 10/2011, so it has no food-contact use in the EU, and notifiers classify it as H302, H312 and H332 with H317 and H410.

HALS vs UV Absorbers: What Is the Difference and Why Combine Them?#

HALS and UV absorbers differ in mechanism: HALS trap the radicals that sunlight creates and protect any thickness, while UV absorbers stop the light itself and protect best in thick or clear parts, so most outdoor plastics combine the two. The difference between UV stabilizers and UV absorbers confuses buyers because the second term names one class inside the first. HALS absorb almost no UV; they intervene after the photon has already done its work. The comparison below sets the two classes against the 9 criteria that decide a formulation.

The two classes are combined because their weaknesses do not overlap. A UV absorber cannot protect the first micrometres of a surface, which is exactly where a HALS works; a HALS cannot reduce the photon flux reaching a pigment, a filler or an underlying layer, which is exactly what an absorber does. For unpigmented and lightly pigmented outdoor parts the UV absorber plus HALS system is therefore the standard, and the BASF technical data sheets for the oligomeric HALS recommend adding Tinuvin 326 or Chimassorb 81 in that case. In a black or heavily filled part the balance shifts back to HALS alone, since the pigment already screens the bulk.

Which UV Stabilizer Is Best for Each Plastic?#

No single UV stabilizer is best for every plastic: polyolefins rely on HALS, PVC on UV absorbers and NOR HALS because its HCl deactivates ordinary HALS, and polycarbonate and PET on heat-resistant UV absorbers in co-extruded cap layers. The polymer decides the weak point, the part geometry decides the class, and the processing temperature decides the grade. Formulators should read the matrix below as a starting point for trials, not as a specification.

How to select a UV stabilizer in 6 steps#

Select a UV stabilizer in 6 steps: identify the polymer's weak point, match the stabilizer to the part thickness, check for acids that deactivate HALS, check volatility at the processing temperature, check the regulatory status in the target market, then confirm by weathering tests. The 6 steps are ordered so that each one removes candidates before the next.

1. Identify the polymer and its weak point: the tertiary C-H of polypropylene, the HCl of PVC, the photo-Fries bonds of polycarbonate, aromatic polyesters and polyurethane.
2. Measure the geometry. Thin film, fibre and tape favour oligomeric HALS, while thick or transparent parts justify adding a UV absorber.
3. Check the chemistry around the stabilizer. Acids from PVC, halogenated flame retardants, sulfur or halogen pesticides and acid-cured paint call for NOR HALS or a low-basicity grade.
4. Check the processing temperature against the volatility data, using the 1 % weight-loss table above to rule out absorbers that do not survive the extruder.
5. Check the market rules. UV-328 is a persistent organic pollutant, UV-320, UV-327 and UV-350 need authorisation for EU use, and food or drinking-water contact restricts the choice to listed grades.
6. Confirm the system by weathering tests against the required service life and the solar dose at the installation site.

Where this sequence sits inside a full formulation exercise, alongside antioxidant, filler and pigment choices, is set out in the general framework on how to select plastic additives.

How Much UV Stabilizer Do Plastics Need? Dosage in wt%#

Most plastics need 0.05-1.4 wt% HALS and 0.1-0.5 wt% UV absorber, with the level set by part thickness, pigmentation, the solar dose at the site and the required service life; agricultural films and co-extruded cap layers go higher. Across all finished plastic products the reported range is wider still, 0.05 to 10 wt%, as compiled by Chea and co-workers in 2025 from the additive inventory of Hahladakis and colleagues from 2018. The table below gives each figure with the context it belongs to.

Supplier TDS ranges; trials set the final level. FDA limits in 21 CFR 178.2010 are legal maxima, not recommended dosages.

Three qualifiers apply to every number above. Legal caps under 21 CFR 178.2010 are maximum use levels for food contact and say nothing about what a part needs. Supplier ranges are per grade and assume the rest of the stabilizer package is present. And the carbon black figure of 2.0-2.5 wt% belongs to polyethylene pressure pipe specifically, not to polyolefins in general.

Worked example: HALS masterbatch and let-down ratio#

A 20 wt% HALS masterbatch let down at 2.5 % puts 0.5 wt% HALS into the finished part, because the final level equals the masterbatch concentration multiplied by the let-down percentage. Most converters add HALS as additive masterbatch rather than as powder, because a 0.3 wt% powder addition is hard to disperse evenly in an extruder.

The arithmetic is 0.20 x 2.5 % = 0.5 %. Reading it backwards is more useful in practice: a target of 0.8 wt% HALS from the same 20 wt% masterbatch needs a let-down of 4.0 %. The numbers here are a calculation example, not a supplier product, although commercial HALS masterbatches exist, for instance the Cyasorb UV-3853PP5 concentrate and the Mayzo BLS 1880PP grade.

Two checks belong with the calculation. The carrier resin must be compatible with the base polymer, and the masterbatch addition must be counted in the total additive budget, since it also brings carrier and any co-additives. Check your own figures with the let-down ratio calculator.

How do solar dose (kLy) and service life set the dose?#

Solar dose is measured in kilolangleys, where 1 kLy equals 1,000 cal/cm2, 41.84 MJ/m2 or about 11.6 kWh/m2, and a site with twice the annual dose consumes a stabilizer system roughly twice as fast. Converters use the unit because it lets a film life be quoted independently of the calendar: an agricultural film sold as a 130 kLy film is guaranteed for a radiant exposure, not for a calendar period. Regional annual values circulate in the trade press but are not verified against a standard or a peer-reviewed source here, so this reference gives none.

Dose is not the only driver. Temperature often matters more than the UV dose because the propagation steps follow Arrhenius kinetics, and a white part running 10-15 °C cooler than a black one ages more slowly at the same radiant exposure. Chemical exposure changes the answer again: Syensqo claims that its Cyasorb Cynergy A series can hold 4 or more years on greenhouse film and 2 or more years on mulch film under burning-sulfur exposure. The dose unit itself is defined under radiant exposure (UV dose).

How Do UV Stabilizers Interact with Other Additives?#

UV stabilizers work inside a larger stabilizer package: phenolic antioxidants and phosphites protect the melt, HALS and UV absorbers protect the part in service, and thioesters, acidic flame retardants, PVC and some pigments weaken basic HALS. A standard outdoor polypropylene package therefore has four layers: a phenolic antioxidant with a phosphite for processing, a thioester or a second phenolic for long-term heat, an acid scavenger such as calcium stearate at up to 1,000 ppm or hydrotalcite to neutralise catalyst residues, and the HALS plus UV absorber pair for light. The melt is protected by antioxidants for plastics, not by HALS, which are weaker than phenolics under processing conditions.

Two colour interactions deserve separate attention because they appear after production rather than during it. The pinking of white polyethylene and polypropylene comes from a phenolic antioxidant over-oxidised to quinones, and it is aggravated by low-surface-treated titanium dioxide, by nitrogen oxides in storage air and by the high pH some UV stabilizers bring. BHT combined with Tinuvin NOR 371 discolours in the dark, which is a shipping problem rather than a weathering one. Synergy and antagonism across all additive families are mapped under additive interactions.

How Is the UV Stability of Plastics Tested?#

The UV stability of plastics is tested by exposing plaques, films or fibres in xenon-arc or fluorescent-UV cabinets, or outdoors, and tracking carbonyl index, melt flow rate, elongation, yellowness and colour at set intervals. Cycle details, filter choices and irradiance settings are covered on accelerated weathering tests. The methods below are the ones cited in polyolefin and engineering-plastic specifications.

Accelerated exposure has limits that no cycle removes. Laboratory weathering reproduces light, heat and moisture, but it does not simulate atmospheric pollution, biological attack or salt water, and no pass or fail threshold is fixed by these standards: the criteria come from the product specification. All methods are indexed under testing plastic additives, including the yellowness index and carbonyl index procedures named above.

How Are UV Stabilizers Regulated?#

UV stabilizers are regulated in 4 layers: REACH controls on the phenolic benzotriazole absorbers, the POP listing of UV-328, food-contact limits in the EU and US, and the EU drinking-water positive list. A fifth instrument reaches one substance only: the nickel quencher UV-1084 falls under the REACH Annex XVII group entry for nickel and its compounds. Every instrument that touches an additive family is summarised in plastic additive regulations, with the dates and thresholds repeated here for the UV stabilizers themselves.

Benzotriazole UV absorbers: SVHC, Annex XIV and the UV-328 POP listing#

UV-328 is banned as a persistent organic pollutant: the Stockholm Convention listed it in 2023, and in the EU it may be present only as a trace contaminant, at up to 100 mg/kg from 4 August 2025, 10 mg/kg from 2027 and 1 mg/kg from 2029. Four phenolic benzotriazoles reached Annex XIV before that, and entries 51 to 54 sit on the REACH Annex XIV authorisation list with a single sunset date. The table below tracks all 6 regulated grades.

All four Annex XIV entries were added by Commission Regulation (EU) 2020/171 of 6 February 2020, with a latest application date of 27 May 2022 and a sunset date of 27 November 2023, and with no exempted uses. UV-326 and UV-329 are not on Annex XIV: the European Chemicals Agency published its draft recommendation on 2 February 2026, the consultation closed on 2 May 2026, and the process is ongoing. Tinuvin 234 is not an SVHC either, but it is under PBT assessment following a written procedure of the PBT Expert Group on 5 September 2025. All 8 phenolic benzotriazoles are tracked under benzotriazole UV absorbers: SVHC, Annex XIV and POPs status.

The UV-328 rules run on their own clock. The Conference of the Parties listed it in Annex A of the Stockholm Convention by decision SC-11/11 in May 2023, the first non-halogenated plastic additive to become a POP, and decision SC-12/14 added an aircraft use-only exemption that expires at the end of 2030. In the EU, Commission Delegated Regulation (EU) 2025/843 was adopted on 5 May 2025, published in the Official Journal on 15 July 2025 and entered into force on 4 August 2025; its derogated uses end on 4 August 2030, and spare parts may run to the end of their service life or 31 December 2043, against the Stockholm replacement-part cap of 2044. EU imports before the listing were around 1,000 tonnes a year, and the REACH registration records manufacture as ceased. One inconsistency remains inside the EU system: UV-327 keeps its food-contact entry FCM 469 in group restriction 12, although its use in the EU has required authorisation since 27 November 2023.

Food contact: EU 10/2011 and FDA 21 CFR 178.2010 limits#

Chimassorb 944 shows how differently the EU and the US limit UV stabilizers in food contact: Regulation (EU) No 10/2011 caps its migration at 3 mg/kg of food, while 21 CFR 178.2010 caps its content at 0.3 wt% of the polypropylene. One system limits what leaves the plastic, the other limits what goes into it. The overall migration limit of 10 mg/dm2 and the generic specific migration limit of 60 mg/kg that frame the EU system are explained on EU 10/2011. The matrix below carries both sides for every grade that has them.

FDA limits are maximum use levels, not recommended dosages; check food type and conditions of use in 21 CFR 178.2010. Not established means that no entry is verified in our source library. EU values checked against the consolidated text of 14 July 2026.

Two rules of reading follow from the matrix. None of these entries is an approval: grades are listed under a section with stated conditions of use, and an entry that covers polypropylene says nothing about polycarbonate. A blend also inherits the status of its components, which is why Tinuvin 783 is usable in EU food contact while Tinuvin 791 is not, its Tinuvin 770 component being absent from Annex I. Food types and conditions of use are decoded on 21 CFR 178.2010.

Drinking-water contact: the EU positive list#

UV stabilizers for plastic parts in contact with drinking water in the EU come from the European positive list under Directive (EU) 2020/2184, which includes 21 of them, from Chimassorb 944 (entry 0648) to Tinuvin 770 (entry 0969). The list spans the types: the HALS Tinuvin 770 (0969), Tinuvin 622 (0627), Chimassorb 944 (0648), Chimassorb 2020 (0687), Chimassorb 119 (0696), Uvinul 4050 H (0700), Uvinul 5050 H (0706) and Cyasorb UV-3346 (1410, under CAS 90751-07-8); the absorbers UV-P (0381), UV-326 (0406), UV-327 (0405), UV-234 (0646), Tinuvin 312 (0547), Tinuvin 1577 (0677), Cyasorb UV-1164 (0389), Uvinul 3030 (0685), Cyasorb UV-3638 (0701), benzophenone-3 (0261) and UV-531 (0368); and the benzoates UV-120 (0415) and Cyasorb UV-2908 (0632).

Food contact and drinking-water contact are separate systems with separate lists, and a grade can sit on one and not on the other. Tinuvin 770 is the clearest case: it holds drinking-water entry 0969 while being absent from Annex I of Regulation (EU) No 10/2011. US and German rules are compared on plastic additives in drinking-water contact, where NSF/ANSI 61 and the KTW assessments apply different criteria again.

Are oligomeric HALS registered under REACH?#

No: oligomeric HALS such as Chimassorb 944, Chimassorb 2020 and Tinuvin 622 are polymers, so REACH exempts them from registration, while monomeric grades such as Tinuvin 770 are registered at 1,000-10,000 tonnes a year. The same exemption covers Cyasorb UV-3346, Cyasorb UV-3529, Hostavin N30 and Uvinul 5050, none of which holds its own registration dossier. Among the other types the nickel quencher UV-1084 is registered at 100-1,000 tonnes a year, and UV-328 records manufacture as ceased.

Who Makes UV Stabilizers? Market, Suppliers and Trade Names#

The UV stabilizer market was worth USD 2.53 billion in 2024 according to MarketsandMarkets, and its main producers are BASF (Tinuvin, Chimassorb, Uvinul), Syensqo (Cyasorb), Clariant (Hostavin), Songwon, Adeka and Sabo. The same analyst projects USD 3.72 billion by 2030, a compound annual growth rate of 6.76 % over 2025 to 2030, and splits the market into HALS, UV absorbers and quenchers, with UV absorbers the second fastest-growing segment. Other analysts publish lower figures, down to about USD 1.7 billion for the same year, so every market figure on this site carries its analyst and date. Segment data for all additive families are on plastic additives market.

Ownership history explains 4 of these names. BASF completed its acquisition of Ciba on 9 April 2009 and inherited the Tinuvin and Chimassorb lines, while Ciba's HALS business went to Sabo as part of the same deal; Solvay acquired Cytec and its Cyasorb line in July 2015, and the resulting specialty business was listed as Syensqo on 11 December 2023. Capacity keeps moving toward Asia: BASF announced a HALS and NOR HALS capacity expansion on 21 April 2026 at Chinaplas, Rianlon was founded in Tianjin in 2003, and Everspring has produced light stabilizers from Taichung since 1988. Chinese UV absorber and HALS producers are listed under plastic additive manufacturers and suppliers in China.

Plants and grades company by company are held in the directory of UV stabilizer and HALS manufacturers. For purchasing, the more useful view is the substance itself, because the same CAS number appears under up to 6 brands.

Equivalence here is an identity statement about the CAS number, not a performance claim: grades differ in physical form, particle size and co-additives. Buyers should compare grades by CAS number and food-contact status, not by trade name. More equivalents are in the plastic additive trade name lookup.

Complete List of UV Stabilizer Substances (44 Pages)#

The complete list below gives all 44 UV stabilizer substances in our substance directory, from HALS such as Chimassorb 944 to benzotriazole absorbers such as UV-328, with CAS number, class and key regulatory status. Rows follow the type order used on this page: HALS first (monomeric, oligomeric, NOR, blends), then the UV absorbers by chemical class, then the hindered benzoates and the nickel quencher.

UV screeners are listed under colorants and fillers: carbon black, titanium dioxide and zinc oxide.

Four of these substances are mainly coatings grades (Tinuvin 292, Tinuvin 400, Tinuvin 479 and Tinuvin 1130) and their pages cover plastics uses only. Every substance links onward from the plastic additives database, with CAS number, dosage, food-contact status and suppliers per grade.

Are UV Stabilizers Toxic? Health, Environment and Recycling#

Most UV stabilizers used in plastics carry no EU harmonised hazard classification, including Chimassorb 944, Tinuvin 622 and Tinuvin 770, while a few benzotriazole absorbers are regulated as very persistent and UV-328 is a banned persistent organic pollutant. Chimassorb 2020, Tinuvin 326, UV-531 and Tinuvin P are unclassified as well, which is why the regulatory pressure on this family concentrates on persistence and bioaccumulation rather than on acute toxicity. Where a substance does carry a classification, the source matters: a harmonised entry in Annex VI of the CLP Regulation is binding, whereas a notified classification only records what registrants have self-declared. A full list of the chemicals of concern across all families is on toxic plastic additives.

Which UV stabilizers are SVHC-listed, restricted or classified?#

The UV stabilizers that are SVHC-listed or restricted are 6 phenolic benzotriazoles (UV-320, UV-326, UV-327, UV-328, UV-329, UV-350) and the nickel quencher UV-1084, while Cyasorb UV-3853 is the only common HALS with a harmonised classification. The 7 regulated cases and 2 watch items are listed below.

• UV-320 and UV-328: SVHC as PBT and vPvB since 17 December 2014, both on Annex XIV; UV-328 additionally a Stockholm Convention POP.
• UV-327 and UV-350: SVHC as vPvB since 17 December 2015, both on Annex XIV.
• UV-326 and UV-329: SVHC as vPvB since 23 January 2024, in the draft Annex XIV recommendation of 2 February 2026, not yet subject to authorisation.
• UV-1084: covered by the REACH Annex XVII group entry for nickel and its compounds.
• Cyasorb UV-3853: harmonised classification Eye Dam. 1 H318, Skin Sens. 1 H317, Aquatic Acute 1 H400 and Aquatic Chronic 1 H410 (CLP Annex VI index 607-383-00-9).
• Benzophenone-3: endocrine-disruptor assessment concluded 22 August 2025, CLH intention registered 1 October 2025, outcome pending.

Tinuvin 770 has no harmonised entry; 90.5 % of notifiers classify it H411 and a minority of 15.4 % notify H361f. Tinuvin 234 is under PBT assessment and is not an SVHC. All listed additives appear on the SVHC Candidate List, which is updated twice a year.

Do UV stabilizers persist in the environment?#

Some UV stabilizers do: UV-328 has a log Kow of 7.93, accumulates in fish and has been found in Arctic seabird eggs, which is why the Stockholm Convention listed it as the first non-halogenated plastic additive POP in 2023. Measured bioaccumulation factors in fish from Canadian rivers give a log BAF of 2.6 to 3.4, and the full POP list is on POPs in plastics.

Persistence rather than toxicity drove every one of these decisions. UV-326 and UV-329 were added to the Candidate List on vPvB grounds alone, without a PBT conclusion, and the same very-persistent, very-bioaccumulative criteria underlie the 2014 and 2015 listings. Detections of UV-328 in eider, kittiwake and glaucous gull eggs and in seabird preen oil are the evidence of long-range environmental transport that a POP listing requires.

Fragmenting plastic is one of the transport routes, because an additive that is not chemically bound to the polymer leaves the fragment over time. How additives leave fragments is covered under microplastics and additive leaching.

Do UV stabilizers affect plastic recycling?#

UV stabilizers do not hinder recycling: the Association of Plastic Recyclers rates them as Design Preferred additives in rigid polypropylene, and recyclers add HALS and UV absorbers back when restabilizing recyclate for outdoor use. Restabilization means rebuilding the stabilizer package that mechanical recycling has consumed, typically a phenol and phosphite combination plus HALS and UV absorbers where the second life is outdoors, as defined by Rudolf Pfaendner, formerly of Ciba and later of Fraunhofer LBF, in Polymer Degradation and Stability in 2022.

Legacy chemistry is the real recycling constraint. Recyclate made from articles produced before the POP listing can still contain UV-328, and that content falls under the EU unintentional trace contaminant limits of 100 mg/kg, then 10 mg/kg from 2027 and 1 mg/kg from 2029. Restabilization packages for second-life material are covered on additives for recycled plastics.

Can UV protection be added to a plastic part after moulding?#

UV protection for plastics is built in before moulding, as a compounded stabilizer, a masterbatch or a UV-absorbing co-extruded cap layer; sprays and paints applied afterwards are coatings, which this reference does not cover. The cap-layer route is the closest thing to a surface treatment inside the plastics process: Tinuvin 360 and Tinuvin 1577 are formulated for direct two-layer co-extrusion of sheet, where a thin heavily loaded skin protects the bulk below it. For an existing moulded part, no additive route exists.

Is a UV stabilizer for pools, candles or archery the same thing?#

No: pool stabilizers, candle UV additives and archery stabilizers share the name only; this page covers additives compounded into plastics. The pool product is a chlorine stabilizer, the candle product is a wax additive and the archery product is a mechanical damper, and none of them belongs to the polymer stabilizer family described here.

Are oxo-degradable additives the opposite of UV stabilizers?#

Yes: oxo-degradable additives are iron, manganese or cobalt salts that speed up photo-oxidation by splitting hydroperoxides, the exact reaction UV stabilizers are added to suppress. The two additive types target the same step of the same cycle in opposite directions, which is why they are never used together. The evidence on oxo additives is weighed on biodegradation additives for plastics.

A short history of UV stabilizers#

The history of UV stabilizers turns on the hindered amine: Sankyo filed the first HALS patent in 1968, and HALS joined UV absorbers as the second pillar of light stabilization once US patent 3,640,928 was published on 8 February 1972. Murayama and co-workers claimed loadings of 0.01 to 5.0 wt%, a range that still brackets industrial practice. The mechanism followed the product by two decades: Denisov published the regenerative cycle in 1991 and Crawford reviewed the absorber photophysics in 1999.

Ownership and regulation shaped the second half of the story. BASF completed the Ciba acquisition on 9 April 2009, Ciba's HALS business moved to Sabo, Solvay bought Cytec and the Cyasorb line in July 2015, and Syensqo was listed on 11 December 2023. UV-328 was named an SVHC in 2014, lost its EU uses at the Annex XIV sunset of 27 November 2023, became a POP in the same year and entered the EU trace-contaminant regime on 4 August 2025, while BASF announced new HALS and NOR HALS capacity on 21 April 2026. The longer arc, from camphor in celluloid onwards, is told in the history of plastic additives.