UV-328 (Tinuvin 328): Properties, Stockholm POP Listing and Regulatory Status

UV-328 (2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, CAS 25973-55-1, sold for decades as Tinuvin 328) is a hydroxyphenyl benzotriazole UV absorber that protected outdoor polyolefins, PVC, polyurethane, styrenics, acrylics and unsaturated polyester from sunlight, and it is the first non-halogenated plastic additive listed as a persistent organic pollutant. Because that listing took effect in the EU on 4 August 2025, the practical question is no longer how UV-328 works but which limits, exemptions and replacements now apply.

Four instruments hold the answer. ECHA placed UV-328 on the REACH Candidate List on 17 December 2014 as a PBT substance under Article 57(d) and a vPvB substance under Article 57(e) of Regulation (EC) No 1907/2006; Commission Regulation (EU) 2020/171 of 6 February 2020 made it entry 51 of REACH Annex XIV with a sunset date of 27 November 2023; the Stockholm Convention added it to Annex A by decision SC-11/11 in May 2023; and Commission Delegated Regulation (EU) 2025/843 of 5 May 2025 wrote it into Annex I Part A of the EU POPs Regulation (EU) 2019/1021 with effect from 4 August 2025. UV-328 is one of 66 UV stabilizer pages in our directory of plastic additives, each with the same identity, dosage and regulatory fields.

This page carries the data-sheet view and the compliance view together: the identity and trade names, the excited-state proton-transfer mechanism, the physical constants that drove the listing, the historical 0.1 to 1.0 wt% dosage across nine polymer groups, the 6 plastics application areas, the persistence and bioaccumulation grounds recorded by the POPs Review Committee, a dated matrix across REACH, Stockholm, the EU POPs and PIC Regulations, EU 10/2011, CLP, FDA, TSCA and Japan's Chemical Substances Control Law, the exemption calendar from 4 August 2030 to 31 December 2043, and the 8 recorded replacements with their CAS numbers and dosage ranges.

Table T1. UV-328 identity card.

Footnote: identity data from PubChem CID 33263; regulatory entries from ECHA CHEM substance 100.043.062, the Stockholm Convention decision texts and the EU and US legal texts cited in each section. Status as of 23 September 2026.

What Is UV-328 (Tinuvin 328)?#

UV-328 is a hydroxyphenyl benzotriazole UV absorber: a benzotriazole ring joined to a phenol that carries two tert-pentyl (tert-amyl) groups, which is why the substance also appears as 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole on older datasheets. The two alkyl groups sit at the 4 and 6 positions of the phenol ring and give the molecule its solubility in hydrocarbon polymers, while the phenolic hydroxyl and the neighbouring triazole nitrogen form the internal hydrogen bond that does the optical work. Its function in a compound was to absorb ultraviolet light before the polymer chain could, which makes it an absorber rather than a radical scavenger. Which substance names, then, does UV-328 actually cover?

The name set is unusually wide because three naming systems meet in it: the IUPAC name, the generic "UV-xxx" grade number and the original Ciba and BASF trade name. As a UV absorber, UV-328 belongs to one of the two working classes of UV stabilizers for plastics, beside the hindered amine light stabilizers, and the class boundary matters because the two work by different physics and are regulated as separate substances. No production route for UV-328 is recorded in our source library, so this page states no synthesis, catalyst or purity data.

What is the CAS number of UV-328?#

The CAS number of UV-328 is 25973-55-1, its EC number is 247-384-8, its molecular formula is C22H29N3O and its molecular weight is 351.5 g/mol. Those four identifiers come from the PubChem record CID 33263, and they are the values that appear in the ECHA CHEM entry 100.043.062, in the Stockholm Convention listing decision and on every supplier datasheet that still exists for the substance.

Is UV-328 the same as Tinuvin 328?#

Yes: UV-328 and Tinuvin 328 are the same substance, CAS 25973-55-1, where Tinuvin 328 was the BASF trade name and UV-328 is the generic grade number that regulators, the Stockholm Convention and Asian producers use. The generic numbering follows the original Ciba and BASF Tinuvin numbers, so UV-327 corresponds to Tinuvin 327, UV-329 to Tinuvin 329 and UV-326 to Tinuvin 326. Generic grade numbers and brand names are matched in the plastic additive trade name lookup.

Which trade names and equivalent grades cover UV-328?#

Four trade names cover UV-328: Tinuvin 328 and Tinuvin PA 328 (BASF, historical), Eversorb 74 (Everlight), GSTAB 328 and BLS 1328 (Mayzo), with Cyasorb UV-2337 recorded as a further synonym. The manufacturers recorded for the substance are BASF as the historical originator, Everlight, Mayzo and non-EU producers that still list a generic UV-328 grade. Brand names that appear on supplier search results without a producer datasheet in our source library are not reproduced here as verified equivalents, because a grade equivalency claim needs a datasheet that names CAS 25973-55-1 and a purity specification. The safe test for a buyer is the CAS number on the certificate of analysis rather than the brand on the bag.

How Does UV-328 Protect Plastics from UV Light?#

UV-328 protects a polymer by absorbing ultraviolet light between roughly 300 and 400 nm and converting it to heat through excited-state intramolecular proton transfer across its internal O-H...N hydrogen bond, so the energy never reaches the polymer chain. The absorbed photon moves the phenolic proton onto the triazole nitrogen, the molecule relaxes through a non-radiative route, the proton returns and the absorber is ready again, which is why a UV absorber is not consumed in the way a phenolic antioxidant is. Crawford set out this photophysics for the benzotriazole class in Progress in Polymer Science 24 (1999), pages 7 to 43. If polyolefins barely absorb sunlight themselves, what is the UV absorber protecting?

The answer is the impurities, not the backbone. Sunlight at the Earth's surface starts at 280 to 290 nm, while aliphatic polyolefins absorb only below about 250 nm, so photo-oxidation begins at hydroperoxides, carbonyl groups and catalyst residues left by polymerisation and processing. A UV absorber therefore competes with those chromophores for the incoming photons, and the initiation steps that it has to outrun are set out under photodegradation of plastics. No UV-328-specific absorption maximum or extinction coefficient is recorded in our source library, so this page gives the class range only.

Why does a UV absorber depend on part thickness?#

A UV absorber follows the Beer-Lambert relationship, so its protection is the product of concentration and path length: the thinner the section, the less UV a given loading can absorb. Coatings practice shows the effect in numbers, because the recommended loading rises as the film gets thinner: 2.5 to 5 wt% on solids at a dry film thickness of 10 to 20 µm, 1.25 to 2.5 wt% at 20 to 40 µm and 0.5 to 1.25 wt% at 40 to 80 µm. Those figures are coatings guidance used here to show the thickness effect and are not a plastics dosage. The same arithmetic explains why co-extruded cap layers, which are thin by design, carry the highest absorber loadings in the whole field, and why a thin film often needs a different stabiliser strategy altogether.

Why was UV-328 always combined with HALS?#

UV-328 was paired with hindered amine light stabilizers because the two mechanisms cover different failure modes: the absorber filters incoming UV through the bulk, while HALS scavenge the radicals that form at the surface, where the absorber is least effective. Denisov described the regenerative nitroxide cycle that makes this work in Polymer Degradation and Stability 34 (1991), pages 325 to 332, and Pieter Gijsman reviewed the mechanism and its limits in Polymer Degradation and Stability 145 (2017), pages 2 to 10. HALS absorb negligible UV and their protection is independent of thickness, which is the exact complement of the Beer-Lambert behaviour above. Coatings practice pairs 1 to 3 wt% UV absorber on solids with 0.5 to 2 wt% HALS, and the radical-scavenging class that partners every UV absorber is covered on hindered amine light stabilizers (HALS).

How is UV protection measured?#

UV stabilizer performance is verified by accelerated weathering rather than by the additive's own specification, with xenon arc and fluorescent UV (QUV) exposure followed by a colour or mechanical measurement. Xenon arc and QUV exposure conditions are described under accelerated weathering tests, and no weathering result, property-retention figure or radiant-exposure value for UV-328 is recorded in our source library, so none is printed here.

What Are the Physical and Chemical Properties of UV-328?#

UV-328 is a solid with a melting point of 80 to 88 °C (176 to 190 °F) according to Mayzo and 80 to 86 °C (176 to 187 °F) according to the Wikipedia data set, a density of 1.17 g/ml and a log Kow of 7.93. The two melting-point ranges are kept apart here with their sources because our source library records both and neither has been reconciled against a producer certificate.

Table T2. Physical and chemical properties of UV-328.

Two of those numbers carry the legal weight. A log Kow of 7.93 and a water solubility near 0.17 µg/L describe a substance that partitions almost entirely into organic phases and lipids rather than into water, and they are the properties behind the PBT and vPvB conclusion that ECHA reached in 2014 and the POPs Review Committee reached later. Both values, and the log BAF range of 2.6 to 3.4 measured in fish from Canadian rivers, reach our source library through a secondary compilation rather than through the primary risk profile, so they are reported here with that source attached.

Which Polymers Used UV-328, and at What Dosage?#

UV-328 was used at 0.1 to 1.0 wt% across styrenics, acrylics, unsaturated polyester, PVC, polyolefins, polyurethane, POM, PVB and elastomers, with the BASF datasheet range running to 1.0 wt% and the Mayzo grade recommended at 0.1 to 0.5 wt%. Coatings formulations used 1 to 3 wt% on solids, which is a different application and a different scope from the plastics compounds covered here. Was that loading unusual for a UV absorber?

It was not. Benzotriazole UV absorbers sit at 0.1 to 0.5 wt% in general plastics as a class, and only co-extruded cap layers reach 5 to 10 wt%, so UV-328 was dosed like its class rather than as a special case. Typical loadings for every additive family sit side by side on additive dosage levels in plastics. No phr value, no masterbatch let-down ratio and no per-polymer split is recorded for UV-328 in our source library, so Table T3 reports the ranges by source rather than inventing a figure for each resin.

Table T3. Recorded UV-328 loadings by polymer group.

UV-328 in polyolefins, PVC and styrenics#

Polyolefins and PVC both needed UV-328 for the same structural reason: neither polymer absorbs significant sunlight itself, so photo-oxidation begins at impurities and defect sites that a UV absorber cannot reach once the chain reaction has started. Pure PVC absorbs nothing above 220 nm, and its degradation runs through defect sites by dehydrochlorination, producing polyene sequences that become visible as colour once eight or more conjugated double bonds line up. Which absorber and stabilizer classes survive in PVC is set out on UV stabilizers for PVC.

Polyolefins dominate the demand side of the whole field, since about 70 % of world light-stabilizer production goes into them, and styrenics sat beside them in the UV-328 application list because polystyrene and ABS yellow quickly outdoors. Polyolefin practice is covered on UV stabilizers for polyethylene.

What Was UV-328 Used For? 6 Application Areas in Plastics#

UV-328 was used in 6 plastics application areas: outdoor polyolefin parts, PVC profiles and film, polyurethane, styrenics, acrylics and unsaturated polyester composites. The 6 areas are listed below in the order in which our source library records them.

• Outdoor polyolefin parts, including moulded articles and film exposed to direct sunlight.
• PVC profiles and film, where colour hold rather than mechanical retention was usually the criterion.
• Polyurethane, both cast and foamed, where yellowing is the first visible failure.
• Styrenics, including polystyrene and ABS.
• Acrylics, where optical clarity had to survive exposure.
• Unsaturated polyester composites, including gel-coated laminates.

Two further uses sit outside the plastics scope of this site and are named once for completeness: industrial coatings and adhesives. Both reappear in the regulatory sections below, because their legal treatment shapes the UV-328 exemption calendar.

Automotive parts and industrial coatings#

Automotive parts and industrial coatings are the largest UV-328 uses that survived the listing, and they are the reason both the Stockholm Convention and the EU wrote derogations rather than a flat prohibition. Decision SC-11/11 records specific exemptions for motor-vehicle parts and for industrial coatings applied to vehicles, engineering machines, rail vehicles and heavy-duty steel structures, and Commission Delegated Regulation (EU) 2025/843 mirrors them as EU derogations for land vehicles and industrial coatings running to 4 August 2030. The reason is service life: a vehicle body or a bridge coating is specified for decades, and a replacement absorber has to be qualified against the same weathering programme before the original can be withdrawn. The full exterior package for vehicle parts is on additives for automotive plastics.

Blood-collection tube separators#

Blood-collection tube separators are a named specific exemption under Stockholm decision SC-11/11 and a named derogation in Commission Delegated Regulation (EU) 2025/843, valid until 4 August 2030. A separator is the gel layer that divides serum or plasma from the cellular fraction after centrifugation, and the exemption exists because the device is a regulated medical product whose validation cannot be repeated quickly. No polymer, no dosage and no device standard for the separator gel is recorded in our source library, so this page describes the legal position only. The derogation is a use permission with an end date, not an assurance of supply, because the EU also prohibits export of UV-328 under the PIC Regulation.

TAC polariser film, photographic paper and LCD instruments#

Triacetyl cellulose film in polarisers, photographic paper and LCD instrument parts form the third exemption group, and they carry the longest end dates in the entire UV-328 calendar. TAC film in polarizers and photographic paper are named specific exemptions under SC-11/11, and the EU derogation for both runs to 4 August 2030. Spare parts for non-medical LCD instruments run considerably longer under Commission Delegated Regulation (EU) 2025/843, until the end of service life or 31 December 2043, whichever comes first, and spare parts for medical LCD instruments run until the end of service life with no calendar date at all. Under the Stockholm Convention the medical LCD position is reviewed by the Conference of the Parties no later than 2041.

Why Was UV-328 Listed as a Persistent Organic Pollutant?#

UV-328 was listed because it is persistent, bioaccumulative and toxic and travels long distances inside plastic debris: the Stockholm Convention added it to Annex A by decision SC-11/11 at COP-11 in May 2023, making it the first non-halogenated plastic additive to become a POP. Annex A is the elimination annex, so the listing obliges Parties to end production and use except where a specific exemption is registered. The depositary notification for the amendment is C.N.77.2024; our source library does not record a confirmed global entry-into-force date for it, so this page cites the decision date and the EU date only. How large was the use that the listing ended?

It was a mid-volume additive, not a commodity. About 1,000 tonnes a year of UV-328 were imported into the EU before the listing, and of the four benzotriazoles sharing the Annex XIV entry block only one was registered under REACH at all, a sign that the class had already retreated from the EU market. The properties behind the decision are the ones in Table T2: a log Kow of 7.93, a water solubility near 0.17 µg/L and detections far from any source. UV-328 sits beside Dechlorane Plus, MCCP, the PBDEs and HBCD on POPs in plastics.

What do PBT and vPvB mean for UV-328?#

UV-328 carries both SVHC grounds at once: ECHA added it to the REACH Candidate List on 17 December 2014 as a PBT substance under Article 57(d) and as a vPvB substance under Article 57(e) of Regulation (EC) No 1907/2006. PBT means persistent, bioaccumulative and toxic, so all three criteria have to be met, including an effect endpoint. vPvB means very persistent and very bioaccumulative, and it needs no toxicity threshold at all, because a substance that neither degrades nor leaves an organism creates an exposure that cannot be predicted or reversed.

The grounds are not the same across the class. UV-320 shares the PBT and vPvB grounds and the 17 December 2014 date, UV-327 and UV-350 were listed on 17 December 2015 as vPvB only, and UV-326 and UV-329 were listed on 23 January 2024 as vPvB only. Neither UV-326 nor UV-329 is a PBT substance, and describing them as such misstates the legal basis of their entries.

Where has UV-328 been found in the environment?#

UV-328 has been detected in Arctic biota, including eider, kittiwake and glaucous gull eggs, and in seabird preen oil, which is the evidence of long-range transport that the POPs Review Committee relied on. Those detections reach our source library through a summary of the POPRC risk profile rather than through the primary monitoring papers, so they are reported as the risk profile records them, without concentrations, sample counts or additional species. The transport pathway the Committee describes is unusual: rather than travelling as a vapour, UV-328 travels inside plastic debris, which is why an additive with a very low vapour pressure reaches polar food webs at all. Additive transport inside plastic debris is covered on plastic additives in the marine environment.

What Is the Regulatory Status of UV-328?#

UV-328 is a REACH Candidate List substance, an Annex XIV substance whose sunset date passed on 27 November 2023, a Stockholm Annex A persistent organic pollutant and, since 4 August 2025, an entry in Annex I Part A of the EU POPs Regulation with a trace limit that steps down from 100 to 1 mg/kg (status 23 September 2026). Table T4 sets out the 13 instruments that touch the substance, with the entry number or limit for each.

Table T4. UV-328 regulatory matrix, status 23 September 2026. ECHA CHEM entries verified 22 September 2026.

Two of those instruments are frequently confused. Authorisation under REACH removes a use unless a company applies for and receives permission, while the POPs Regulation prohibits the substance outright and writes back a closed list of derogations with fixed end dates. Registration, evaluation and authorisation are explained on REACH and plastic additives; the POPs mechanism is the one that now governs UV-328.

Is UV-328 an SVHC, and does it need REACH authorisation?#

Yes on both counts: UV-328 has been on the REACH Candidate List since 17 December 2014, and it is entry 51 of Annex XIV, so any EU use has required an authorisation since the sunset date of 27 November 2023. The Annex XIV decision is Commission Regulation (EU) 2020/171 of 6 February 2020, and the latest application date was 27 May 2022, the deadline by which a company had to file in order to keep using the substance while its decision was pending. Those three dates are distinct, and a page reporting UV-328 as "banned in 2020" or giving the sunset as 2022 has merged them. Every plastic additive on the list, with its inclusion date, is tabulated on the SVHC Candidate List.

No company applied. The ECHA Annex XIV entry records no exempted uses, and the registration status for the substance is ceased manufacture with 11 inactive dossiers, so the authorisation route closed without ever being used and the POPs listing overtook it. Entries 51 to 54 and their sunset dates are listed on the REACH Annex XIV authorisation list.

Is UV-328 banned in the EU?#

Yes: manufacturing, placing on the market and using UV-328 is prohibited in the EU under Annex I Part A of the POPs Regulation (EU) 2019/1021, added by Commission Delegated Regulation (EU) 2025/843 of 5 May 2025, published in the Official Journal on 15 July 2025 and in force since 4 August 2025. The prohibition is not absolute in practice. An unintentional trace contaminant limit of 100 mg/kg applied from 4 August 2025, falls to 10 mg/kg on 4 August 2027 and falls again to 1 mg/kg on 4 August 2029, so a substance, mixture or article that carries UV-328 below the limit in force is not caught.

A second qualification is the derogation list. Land vehicles, industrial coatings, blood-collection tube separators, TAC polariser film, photographic paper and civil and military aircraft keep a permitted use until 4 August 2030, spare parts run to the end of service life or 31 December 2043 depending on the category, and articles already in use before an expiry may continue to be used. The full calendar, with the Stockholm equivalents beside it, is in the exemption section below.

What is an unintentional trace contaminant (UTC) limit?#

An unintentional trace contaminant limit is the concentration below which a POP may still be present in a substance, mixture or article without the prohibition being breached, because it arrived as an impurity rather than as a deliberate addition. For UV-328 the limit is 100 mg/kg from 4 August 2025, 10 mg/kg from 4 August 2027 and 1 mg/kg from 4 August 2029, all set by Commission Delegated Regulation (EU) 2025/843. UTC values are set per substance: Dechlorane Plus, listed at the same COP, carries 1,000 mg/kg until 15 April 2028 and 1 mg/kg thereafter under the same Annex I. No EU POPs waste concentration limit for UV-328 is recorded in our source library, so this page states none.

Which uses of UV-328 are still exempt, and until when?#

Six categories of use stay legal under the Stockholm Convention's specific exemptions for UV-328, and the EU has written matching derogations with its own end dates. The 6 Stockholm categories are listed below as decision SC-11/11 records them.

• Motor-vehicle parts.
• Industrial coatings for vehicles, engineering machines, rail vehicles and heavy-duty steel structures.
• Blood-collection tube separators.
• Triacetyl cellulose film in polarizers.
• Photographic paper.
• Replacement parts, ending at the end of service life or in 2044, whichever comes first, with medical LCD parts reviewed by the Conference of the Parties no later than 2041.

Decision SC-12/14 at COP-12 in 2025 added a seventh, narrower entry after the original six: an aircraft use-only exemption covering water-seal tape, polyurethane and polyamide adhesives and polyurethane coatings, expiring at the end of 2030. Which Parties registered which exemption is recorded in the Register of Specific Exemptions kept by the Convention secretariat; that register is not in our source library, so no country is named here.

Table T5. UV-328 exemption and expiry calendar.

Footnote: the EU spare-parts cap is 31 December 2043; the Stockholm replacement-part cap is 2044. The two are different instruments and are not interchangeable. Articles already in use before an expiry may continue to be used.

Is UV-328 restricted outside the EU?#

Japan restricts UV-328 the most sharply outside the EU: Cabinet Order No. 382 of 18 December 2024 designated it a Class I Specified Chemical Substance under the Chemical Substances Control Law with effect from 18 February 2025, and an import ban on listed products containing it applies from 18 June 2025. The Cabinet decision preceding the order was taken on 13 December 2024, and the Class I designation is Japan's strongest chemical control category, covering manufacture, import and use.

The EU also bans export. UV-328 sits in Annex I and Annex V of the PIC Regulation, so it cannot be shipped out of the Union even to a market where it remains legal. The United States takes the opposite position: UV-328 remains active on the TSCA Inventory and the United States is not a Party to the Stockholm Convention, so no federal POPs prohibition applies. Inventory status and risk evaluations are explained on TSCA and plastic additives.

Is UV-328 allowed in food-contact plastics?#

No: UV-328 is not in Annex I of Regulation (EU) No 10/2011, so it has never been usable in EU plastic food-contact materials, and it does not appear in the FDA's polymer stabilizer list at 21 CFR 178.2010 either. The Union list and its group restrictions are explained on EU 10/2011, and the benzotriazoles that do hold entries sit together in group restriction 12, where UV-P (FCM 444), UV-327 (FCM 469) and UV-326 (FCM 470) share a total specific migration limit of 30 mg/kg.

The one US clearance is narrow: 21 CFR 175.105 lists UV-328 for adhesives under its di-tert-amyl name, a component clearance for an adhesive layer and not an authorisation for a food-contact plastic. How 21 CFR 175.105 differs from 178.2010 is set out on FDA food contact rules for plastic additives.

Is UV-328 Hazardous? Health, Safety and Environmental Profile#

UV-328 has no harmonised hazard classification under the EU CLP Regulation (EC) No 1272/2008; the classification that companies notified to ECHA is H373 (86 % of notifiers) and H413 (88 %), with a minority reporting H372 and H410. The three pieces of classification evidence on record are listed below.

• Harmonised classification: none. No entry exists in Annex VI of the CLP Regulation, so no classification is legally binding across the EU.
• Notified classification: H373 (may cause damage to organs through prolonged or repeated exposure) from 86 % of notifiers and H413 (may cause long lasting harmful effects to aquatic life) from 88 %, with H372 and H410 reported by a minority.
• Regulatory grounds: PBT under Article 57(d) and vPvB under Article 57(e) of REACH, based on persistence and bioaccumulation rather than on an acute effect.

That distinction is the one most summaries of UV-328 blur. The worldwide action against the substance rests on persistence and bioaccumulation, on a log Kow of 7.93 and a log BAF in fish of 2.6 to 3.4, and on its detection in organisms far from any point of release. It does not rest on an acute toxicity classification, which is why describing UV-328 as a toxic chemical additive is imprecise even though the substance is prohibited. Why a substance can be restricted worldwide without a harmonised health classification is discussed under toxic plastic additives.

No LD50, NOAEL, PNEC or DNEL value for UV-328 is recorded in our source library, so none appears here, and the substance is described neither as safe nor as highly toxic, because neither word matches the evidence on file.

What Can Replace UV-328?#

Eight substances are recorded as replacements for UV-328: the benzotriazoles Tinuvin 928, Tinuvin 234 and Tinuvin 360, the hydroxyphenyl triazines Tinuvin 1577, Tinuvin 400, Tinuvin 479 and Cyasorb UV-1164, and the oxanilide Tinuvin 312. Which of them is a drop-in, and which changes the formulation? Chemistry class, molecular weight and food-contact status decide, and Table T6 compares the seven substances for which a full identity and regulatory record exists.

Table T6. UV-328 and its recorded replacements. SVHC status checked 22 September 2026.

Footnote: Tinuvin 400 (CAS 153519-44-9, liquid hydroxyphenyl triazine, 0.5 to 1.0 wt% in plastics and adhesives) and Tinuvin 479 (CAS 204848-45-3, red-shifted biphenyl triazine) are the two further recorded alternatives; neither is listed in Annex I of EU 10/2011.

The pattern across the table is molecular weight. Every recorded replacement except the oxanilide is heavier than UV-328, and all five absorber chemistries are compared on UV absorbers.

UV-328 vs Tinuvin 928#

Tinuvin 928 is the closest same-class replacement for UV-328: it is the benzotriazole that the industry positions as the non-SVHC substitute, at CAS 73936-91-1 and a molecular weight of 441.6 g/mol against UV-328's 351.5 g/mol. The higher molecular weight is the point, because it lowers volatility and extraction loss compared with the low-molecular-weight benzotriazoles that the Candidate List has been working through since 2014. Tinuvin 928 has EC number 422-600-5 and formula C29H35N3O, it is registered under REACH at 1,000 to 10,000 tonnes a year, it is not an SVHC as of 22 September 2026 and it is not listed in Annex I of Regulation (EU) No 10/2011. Tinuvin 928 is the benzotriazole positioned as the non-SVHC substitute for UV-328. Our source library records only a coatings dosage, 1 to 3 wt% on solids with 0.5 to 2 wt% HALS, so no plastics loading is printed here.

UV-328 vs Tinuvin 234 and Tinuvin 360#

Tinuvin 234 and Tinuvin 360 replace UV-328 where the compound is processed hot: both are high-molecular-weight benzotriazoles at 447.6 and 658.9 g/mol, and Tinuvin 234 is the only one of the two listed for EU food contact, as FCM 738 with an SML of 1.5 mg/kg. Tinuvin 234 (CAS 70321-86-7) is dosed at 0.15 to 0.60 wt%, and the FDA caps it at 3.0 wt% in polycarbonate and 0.5 wt% in PET. It is not an SVHC, but ECHA is running a PBT assessment on it, taken forward by the PBT Expert Group in a written procedure of 5 September 2025. Tinuvin 234 is FCM 738 with an SML of 1.5 mg/kg.

Tinuvin 360 (CAS 103597-45-1) is the bis-benzotriazole, a single molecule carrying two benzotriazole units, dosed at 0.2 to 1.0 wt% and not listed in Annex I of Regulation (EU) No 10/2011; its harmonised classification rests on the RAC opinion of 5 December 2017. Tinuvin 360 is the bis-benzotriazole at 658.9 g/mol for high-temperature engineering plastics.

UV-328 vs the hydroxyphenyl triazines#

The hydroxyphenyl triazines are the class that changes the food-contact answer: Tinuvin 1577 is FCM 770 with an SML of 0.05 mg/kg and Cyasorb UV-1164 is FCM 452 with an SML of 5 mg/kg, while UV-328 never had an Annex I entry at all. Tinuvin 1577 (CAS 147315-50-2, 425.5 g/mol) is dosed at 0.2 to 1.0 wt% and capped by the FDA at 0.5 wt% in polycarbonate, polyester elastomers and PET. Tinuvin 1577 carries an SML of 0.05 mg/kg as FCM 770.

Cyasorb UV-1164 (CAS 2725-22-6, 509.7 g/mol) carries the FDA caps that matter for polyolefins: 0.3 wt% in olefin polymers, 0.1 wt% in polypropylene and 0.04 wt% in polyethylene of density 0.94 and above, and no numeric plastics dosage for it is recorded in our source library. Two further triazines complete the class: Tinuvin 400 (CAS 153519-44-9), a liquid grade used at 0.5 to 1.0 wt% in plastics and adhesives, and Tinuvin 479 (CAS 204848-45-3), a red-shifted biphenyl triazine registered under REACH at 10 to 100 tonnes a year. Cyasorb UV-1164 is FCM 452 with an SML of 5 mg/kg and FDA caps for olefin polymers.

UV-328 vs Tinuvin 312 and the non-benzotriazole options#

Tinuvin 312 leaves the benzotriazole class entirely: it is an oxanilide, listed as FCM 633 with an SML of 30 mg/kg, dosed at 0.05 to 0.5 wt% by Mayzo and 0.10 to 1.0 wt% on the BASF datasheet, and it does not interact with the copper-based heat stabilizers used in polyamide. At 312.4 g/mol it is lighter than UV-328 and it absorbs most strongly in the UV-B, which makes it a different optical filter rather than a like-for-like swap. Tinuvin 312 is the oxanilide that does not interact with copper-based polyamide heat stabilizers. A hindered amine light stabilizer remains necessary alongside any of these absorbers, because none of them protects the surface layer where radical formation concentrates.

How to check a replacement before switching#

A replacement for UV-328 should be checked against the 4 criteria listed below before the formulation changes.

1. Check the Candidate List and the Annex XIV recommendation status of the candidate, not only its current entry.
2. Check the EU 10/2011 FCM number and SML and the 21 CFR 178.2010 cap for the exact polymer and food type in question.
3. Check the dosage range against the part thickness, because a UV absorber's effect is concentration multiplied by path length.
4. Check the HALS partner, because the absorber alone does not protect the surface.

Candidate List, FDA and EU 10/2011 status for a candidate can be looked up in the additive regulatory status checker.

Who Still Supplies UV-328, and What Must Buyers Check?#

UV-328 is no longer manufactured for the EU market: ECHA records no active REACH registration and 11 inactive dossiers with the status ceased manufacture, and the EU also prohibits its export under Annexes I and V of the PIC Regulation. BASF, which originated the substance as Tinuvin 328 and Tinuvin PA 328, is recorded as a historical producer, and the other named producers are Everlight (Eversorb 74), Mayzo (BLS 1328) and GSTAB.

Non-EU producers still list generic UV-328 grades, which is why an EU importer's real exposure is the trace level in imported compounds and finished articles rather than a purchase decision. A compound bought outside the EU can carry UV-328 legally in its country of origin and breach the POPs Regulation when it crosses the border. Producers of the replacement chemistries are listed in the directory of UV stabilizer and HALS manufacturers. No price data for UV-328 is recorded in our source library, so this page states no price.

Table T7. UV-328 producers, trade names and status.

Footnote: trade names are those recorded in our source library. Brand equivalents seen on supplier search results but not verified against a producer datasheet are excluded.

A buyer importing compounds or articles into the EU should run the 4 checks listed below before accepting a delivery.

• Request a UV-328 content statement against the applicable unintentional trace contaminant limit: 100 mg/kg now, 10 mg/kg from 4 August 2027 and 1 mg/kg from 4 August 2029.
• Check whether the article falls under a derogated use and record its end date, 4 August 2030 for most categories and 31 December 2043 for spare parts.
• Check the supply chain for legacy and recycled input, because recyclate carries additives that were legal when the original article was made.
• Keep the supplier declaration dated, because the limit changes twice more before 2030.

How Does UV-328 Fit into the Benzotriazole UV Absorber Family?#

UV-328 is the most heavily regulated member of the hydroxyphenyl benzotriazole class, the group of UV absorbers that also contains UV-P, UV-320, UV-326, UV-327, UV-329, UV-350, Tinuvin 234, Tinuvin 360 and Tinuvin 928. The class sits inside a UV stabilizer market that MarketsandMarkets valued at USD 2.53 billion in 2024 and projected at USD 3.72 billion in 2030, a compound annual growth rate of 6.76 %, in its May 2025 report, with about 70 % of light stabilizers going into polyolefins. The full class, from UV-P to Tinuvin 1130, is covered on benzotriazole UV absorbers, and its regulatory history runs in three waves: 2014, 2015 and 2024.

UV-320, UV-327 and UV-350: the other Annex XIV benzotriazoles#

Three further benzotriazoles share UV-328's Annex XIV entry block: UV-327 (entry 52), UV-350 (entry 53) and UV-320 (entry 54), all added by Commission Regulation (EU) 2020/171 with the same latest application date of 27 May 2022 and the same sunset date of 27 November 2023. UV-320 (CAS 3846-71-7, 323.4 g/mol) shares UV-328's 17 December 2014 inclusion date and its PBT and vPvB grounds, while UV-327 (CAS 3864-99-1, 357.9 g/mol) and UV-350 (CAS 36437-37-3, 323.4 g/mol) were listed on 17 December 2015 on vPvB grounds alone.

One anomaly in that block is worth stating plainly. UV-327 still holds an EU food-contact entry as FCM 469 inside group restriction 12, with a total specific migration limit of 30 mg/kg shared with UV-P and UV-326, even though its EU use has required an authorisation since 27 November 2023. Tinuvin 327 (UV-327) is entry 52 of Annex XIV, and UV-350 is entry 53, listed as vPvB on 17 December 2015.

UV-326 and UV-329: the next benzotriazoles in line#

UV-326 and UV-329 joined the Candidate List on 23 January 2024 on vPvB grounds only, and ECHA published a draft Annex XIV recommendation covering both on 2 February 2026, with the consultation closed on 2 May 2026 and the decision still open at 22 September 2026. Neither substance is on Annex XIV today, so neither requires an authorisation, and neither is a PBT substance. Tinuvin 326 (UV-326, bumetrizole) is CAS 3896-11-5 and is FCM 470 in group restriction 12.

Octrizole, the second of the pair, is CAS 3147-75-9, it is not listed in Annex I of Regulation (EU) No 10/2011, and the FDA caps it at 0.5 wt% in polycarbonate under conditions of use E, F and G. Suppliers outside the EU most often propose UV-329 (Tinuvin 329, octrizole) as a UV-328 substitute, a substitution that the Candidate List entry of 23 January 2024 already qualifies.

UV-328 in recycled plastic and legacy articles#

Recycled polyolefin and PVC streams are where UV-328 now surfaces, because articles placed on the market before the restriction may stay in use and their material eventually returns as feedstock. The practical consequence is a moving target: the unintentional trace contaminant limit that a recycler has to meet falls to 10 mg/kg on 4 August 2027 and to 1 mg/kg on 4 August 2029, so a recyclate stream that passes today can fail twice before 2030. A separate obligation applies upstream, since SCIP notification to ECHA has been required for Candidate List substances present above 0.1 % w/w in an article since 5 January 2021. How restricted additives return through recyclate is covered on legacy additives in recycled plastic.

Is UV-328 banned in the United States?#

No: UV-328 remains active on the TSCA Inventory, and the United States is not a Party to the Stockholm Convention, so no federal POPs prohibition applies to it. The one federal clearance on record is 21 CFR 175.105, which lists the substance for adhesives.

Is UV-328 still allowed in adhesives?#

In the United States, yes: 21 CFR 175.105 lists UV-328 under its di-tert-amyl name for adhesives, a use that sits outside this site's plastics scope.

When do the last UV-328 exemptions expire?#

The last EU derogation runs to 31 December 2043, for spare parts for vehicles and for stationary agricultural, forestry and construction machines, while medical LCD spare parts end with the service life of the instrument.