UV Stabilizers for PVC: 6 Stabilizer Classes, Dosage and Selection

UV stabilizers for PVC are UV absorbers and UV-screening pigments, mainly benzotriazoles, benzophenones and rutile titanium dioxide, that are added at about 0.1 to 1.0 wt% (up to 5 wt% in co-extruded cap layers) to stop sunlight from yellowing and embrittling the polymer. PVC differs from polyethylene and polypropylene because the hydrogen chloride (HCl) it releases under sunlight deactivates most hindered amine light stabilizers (HALS), so which stabilizers still work in PVC is the question that decides every outdoor formulation, from a window profile to a roofing membrane.

About 70% of EU PVC goes into building and construction (VinylPlus, 2023), which makes window profiles, siding, pipe and roofing the main outdoor uses for this group of plastic additives. Six classes of UV stabilizer cover that range: rutile titanium dioxide (TiO2) as a UV screener, four chemistries of UV absorber (benzotriazoles, benzophenones, cyanoacrylates and oxanilides), and a narrow group of low-basicity hindered amine light stabilizers that tolerate the acid PVC releases.

This page sets out how sunlight degrades PVC, the six stabilizer classes and the named grades sold under each one, why conventional HALS fail while NOR HALS and low-basicity HALS survive, the dosage by application from window profile to roofing membrane, how UV stabilizers interact with the rest of the PVC additive package, how their performance is tested, and which grades are cleared for food contact and drinking water.

• 6 stabilizer classes protect PVC against UV: rutile TiO2, four UV-absorber chemistries and NOR/low-basicity HALS
• 0.3 to 0.5 wt% Tinuvin 571 in mass-stabilized PVC, up to 5 wt% in co-extruded cap layers
• About 10% TiO2 loading in vinyl-siding capstock
• pKb about 8 to 10 for NOR HALS versus 4 to 5 for N-H HALS, the reason only NOR HALS keep working once PVC releases HCl

Why Does PVC Need UV Stabilizers?#

PVC needs UV stabilizers because sunlight, absorbed by defects, hydroperoxides and carbonyl groups in the resin, strips hydrogen chloride from the chain and leaves conjugated polyene sequences that turn the surface yellow and brittle. The hub on UV stabilizers for plastics compares the same six classes across every polymer, since the additive chemistry overlaps between PVC, polyolefins and engineering plastics even though the underlying photochemistry differs by backbone. Left unprotected, outdoor PVC loses hydrogen chloride within weeks of exposure and starts to discolor before any mechanical property changes are visible.

How does sunlight degrade PVC?#

Sunlight degrades PVC through photo-initiated dehydrochlorination: pure PVC absorbs no UV radiation above 220 nm, but structural defects, hydroperoxides and carbonyl groups absorb the sunlight that reaches the ground (which starts at 280 to 290 nm) and trigger a radical reaction that releases hydrogen chloride. Temperature often matters more than the UV dose itself in this reaction, since both the thermal and photochemical routes follow Arrhenius kinetics: thermal HCl elimination during processing begins slowly at 100 to 120 degC and becomes rapid near 250 degC, so processing damage and weathering damage add to the same underlying chemistry rather than acting as separate mechanisms.

The degradation runs through four linked steps:

1. Chromophores (defects, hydroperoxides and carbonyl groups) absorb UV radiation above 290 nm.
2. Radicals formed on the polymer chain abstract hydrogen and release hydrogen chloride.
3. The lost HCl leaves conjugated carbon to carbon double bond sequences, called polyenes, along the chain.
4. Polyenes with 8 or more conjugated double bonds absorb visible light and appear yellow to brown.

The same HCl-loss chemistry that runs during processing is covered in detail under PVC thermal degradation and dehydrochlorination, which treats the reaction as a formulation and process-temperature problem rather than a weathering one.

What are the signs of UV degradation in PVC?#

UV-degraded PVC shows five typical signs, listed below. Yellowing to browning follows directly from the polyene sequences described above, while chalking and gloss loss come from surface erosion of the resin around exposed pigment particles.

• Yellowing or browning of the surface
• Surface chalking
• Gloss loss
• Fine surface crazing
• Loss of impact strength

Polyolefins, polycarbonate and PET degrade through different mechanisms; the pathways are compared on photodegradation of plastics, since PVC is the only major commodity polymer whose UV damage is driven primarily by dehydrochlorination rather than chain scission or crosslinking.

Is PVC UV resistant?#

No: unstabilized PVC is not UV resistant, and it becomes suitable for outdoor use only when rutile titanium dioxide, a UV absorber or, in flexible grades, a NOR HALS is compounded into it. The polymers that resist UV without any additive are listed under UV-resistant plastics, a much shorter list than the polymers that need a stabilizer package to survive outdoors.

What Are the 6 Types of UV Stabilizers for PVC?#

The 6 types of UV stabilizers used in PVC are rutile titanium dioxide as a UV screener, benzotriazole, benzophenone, cyanoacrylate and oxanilide UV absorbers, and NOR or low-basicity HALS, with titanium dioxide protecting most opaque rigid PVC and UV absorbers protecting clear and flexible PVC. Titanium dioxide covers the largest volume of opaque rigid PVC by weight, the four UV-absorber chemistries protect clear and flexible grades in proportion to concentration and part thickness, and NOR and low-basicity HALS remain the narrow exception among hindered amine light stabilizers that continue to function once PVC starts releasing hydrogen chloride.

1. UV screeners: rutile titanium dioxide#

Rutile titanium dioxide is the white pigment that protects most opaque rigid PVC from sunlight: its high refractive index scatters visible light and screens UV radiation in the surface layer, so white window profiles, siding and pipe carry it as both colorant and UV stabilizer. The pigment grade used is rutile TiO2 (CAS 13463-67-7, EC 236-675-5, Colour Index Pigment White 6), with an optimal crystal size of about 220 nm for maximum scattering efficiency; the anatase crystal form is not used for this purpose in PVC. Grades, surface treatments and full regulatory status are covered on titanium dioxide (TiO2) in plastics.

Loadings scale with the application: US vinyl siding uses a co-extruded capstock that carries about 10% TiO2 and makes up to 25% of the total wall thickness, while the Plastics Pipe Institute's TR-2-2023 range composition for US pressure pipe sets rutile TiO2 at 0.5 to 3.0 phr. TiO2, ZnO and carbon black are compared in full on UV screeners, the page covering all three UV-screening pigments used across plastics.

Titanium dioxide carries no harmonised EU hazard classification in force. The General Court of the European Union annulled the Carcinogen Category 2 entry for TiO2 in Regulation (EU) 2020/217 on 23 November 2022, and the Court of Justice of the EU dismissed the appeals against that judgment on 1 August 2025.

2. Benzotriazole UV absorbers#

Benzotriazole UV absorbers convert UV photons into heat through an intramolecular proton transfer, and because they follow the Beer-Lambert law, their protection in PVC grows with concentration and part thickness. J. Crawford described this excited-state intramolecular proton transfer (ESIPT) mechanism in Progress in Polymer Science in 1999, and the same paper set the working absorption range for benzotriazole UV absorbers at 300 to 400 nm.

Four benzotriazole grades are named for PVC in current use, plus one now historical. Tinuvin 571 is a liquid benzotriazole used at 0.3 to 0.5 wt% in mass-stabilized PVC and up to 5 wt% in co-extruded cap layers. Tinuvin P (UV-P) runs at 0.1 to 0.5 wt% in rigid PVC, forms coloured complexes with iron and cobalt ions, and loses 1% of its mass by 153 degC in thermogravimetric analysis, which marks it as comparatively volatile. Tinuvin 234 runs at 0.15 to 0.60 wt% (BASF technical data) and is far less volatile, losing 1% of its mass only at 264 degC. UV-329 is used in rigid and flexible PVC at 0.1 to 0.5 wt% but carries an SVHC status covered in the regulatory section below; UV-328, once a common PVC choice, is now historical only. Full grade and volatility comparisons sit on benzotriazole UV absorbers.

3. Benzophenone UV absorbers#

Benzophenone UV absorbers such as UV-531 are the classic choice for flexible PVC film and sheet at 0.1 to 0.7 wt%, although BASF positions them for moderate-durability applications because their long-term stability is lower than that of benzotriazoles. UV-531 (Chimassorb 81, octabenzone, CAS 1843-05-6) performs best in films thicker than 100 micrometres and in thick sections, per Mayzo's BLS 531 technical data sheet. Benzophenone-3 (oxybenzone) is also listed for PVC in our source library, but no independent plastics dosage figure is documented for it, so no PVC loading is given here. The full class, including their shared EU migration limit, is profiled on benzophenone UV absorbers.

4. Cyanoacrylate UV absorbers#

Cyanoacrylate UV absorbers such as Uvinul 3035 and liquid octocrylene protect colourless and flexible PVC at 0.1 to 1.0 wt% (BASF technical data), with octocrylene suited to plastisols because it is a liquid. Uvinul 3035 (etocrylene, CAS 5232-99-5) is used for colourless transparent parts and loses 1% of its mass at 205 degC in thermogravimetric testing. Octocrylene (CAS 6197-30-4, sold as Uvinul 3039) absorbs across 280 to 320 nm and is also used as a sunscreen filter outside plastics, a use that falls outside the scope of this page. Both grades and their EU migration limits are compared on cyanoacrylate UV absorbers.

5. Oxanilide UV absorbers#

Oxanilide UV absorbers such as Tinuvin 312 absorb mainly UV-B and do not discolour or react with metal ions or alkaline additives, which suits them to rigid and flexible PVC at 0.05 to 1.0 wt%. BASF's technical data sheet gives 0.10 to 1.0 wt% for rigid and flexible PVC including plastisols, while Mayzo's BLS 1312 sheet gives a narrower 0.05 to 0.5 wt%; both apply to the same grade, CAS 23949-66-8. Tinuvin 312 loses 1% of its mass at 200 degC and is compatible with optical brighteners, a combination that matters where clear or bright-white PVC parts need both properties at once. Tinuvin 312 is listed in EU 10/2011 with a specific migration limit of 30 mg/kg, covered in the food-contact section below.

6. NOR HALS and low-basicity HALS#

NOR HALS such as Tinuvin 123 and low-basicity oligomeric HALS such as Uvinul 5050 H are the only hindered amine light stabilizers that keep working in PVC, because their pKb of about 8 to 10 leaves little basic nitrogen for hydrogen chloride to neutralise. Tinuvin 123 is a liquid NOR HALS used at 0.05 to 0.5 wt% in plastics exposed to acids, per Mayzo's BLS 123 data sheet; that range is a general plastics figure rather than a PVC-specific one. Uvinul 5050 H is described by its supplier only as "low basicity," with no pKb value assigned to it, and is used at 0.1 to 1.0 wt% in polyolefins and PVC. NOR HALS, structures and their acid tolerance are covered together with their agricultural-film uses on NOR HALS, and the mechanism that lets them survive PVC's HCl is explained fully in the next section.

Why Do Conventional HALS Fail in PVC?#

Conventional HALS fail in PVC because the hydrogen chloride released by dehydrochlorination protonates their basic piperidine nitrogen, which stops the Denisov cycle through which HALS trap radicals. E.T. Denisov described this radical-trapping cycle in Polymer Degradation and Stability in 1991: a HALS is not consumed stoichiometrically but regenerates its active aminoxyl radical repeatedly, and it absorbs almost no UV itself, so a protonated, deactivated HALS leaves the polymer with no working stabilizer at all rather than one working at reduced efficiency.

Basicity, expressed as pKb, sets which HALS types survive:

pKb values are approximate, from BASF technical literature. Some suppliers list N-methyl HALS such as Tinuvin 765 for PVC and PVC plastisols at 0.1 to 1.0 wt%, but the published literature treats NOR HALS as the reliable exception to HALS failure in PVC, and this page follows that distinction rather than the plastisol listing.

UV absorbers and TiO2 are therefore the default in PVC: they do not depend on a basic nitrogen, but they protect in proportion to concentration and thickness, which is why cap layers carry up to 5 wt% while mass-stabilized sections need only 0.3 to 0.5 wt%. How hindered amine light stabilizers (HALS) regenerate through the Denisov cycle in polyolefins, where basicity is not a constraint, is explained in full on the HALS page.

Which UV Stabilizer Is Best for Each PVC Application?#

The best UV stabilizer for PVC depends on whether the part is opaque or clear, rigid or flexible, and mass-stabilized or cap-layered: rutile TiO2 for white rigid profiles and pipe, a liquid benzotriazole in co-extruded cap layers, UV-P or Tinuvin 234 in clear rigid PVC, and benzophenone, cyanoacrylate or oxanilide absorbers in flexible PVC.

Supplier TDS ranges are in wt% of the compound unless marked phr; trials decide the final level.

Rigid PVC window profiles and siding#

White PVC window profiles and vinyl siding rely on rutile titanium dioxide as their UV stabilizer, concentrated in the weathering surface: in US siding, the co-extruded capstock makes up to 25% of the wall thickness and carries about 10% TiO2, over a substrate of about 15% ground limestone in a profile that is roughly 80% PVC resin by weight overall. Rigid uPVC window profiles typically carry 5 to 15% calcium carbonate (stearate-coated chalk or marble) as filler alongside the pigment package, and weatherable profiles use acrylic core-shell impact modifiers such as Paraloid KM-361 rather than butadiene-based types, since IR-reflective inorganic pigments also help by reducing the heat build-up that warps dark profiles and siding. US weatherable siding and window profiles mainly use butyltin mercaptide as the heat stabilizer, while EU profiles run predominantly on calcium-zinc and calcium-organic one-pack systems positioned for weathering performance. The full profile recipe, including filler and impact-modifier levels, is on additives for PVC window profiles; no complete phr-level EU window-profile recipe is documented in our substance directory, so none is published here.

Co-extruded cap layers and capstock#

Co-extruded cap layers concentrate the UV absorber where sunlight arrives: a liquid benzotriazole such as Tinuvin 571 is used at up to 5 wt% in the cap, against 0.3 to 0.5 wt% when the whole PVC section is mass-stabilized. This difference follows directly from the Beer-Lambert law: a thin, highly loaded surface layer absorbs the same total UV dose as a thicker, lightly loaded section, so concentrating the absorber where the light actually strikes is more efficient than distributing it through the full wall thickness. Tinuvin 571 is supplied as a liquid, which simplifies metering into cap-layer compounds during co-extrusion.

PVC pipe and conduit#

PVC pipe and conduit are UV-protected mainly by rutile titanium dioxide, which the Plastics Pipe Institute's TR-2-2023 range composition for US pressure pipe sets at 0.5 to 3.0 phr, alongside a tin stabilizer at 0.3 to 1.0 phr. A worked example from that range composition totals 108.03 phr for the full compound, of which 0.50 phr TiO2 equals 0.46 wt% of the finished pipe. This section covers only the additive chemistry; installation questions such as schedule ratings, above-ground exposure limits and painting are answered on additives for PVC pipe, the page that owns those queries.

Clear rigid PVC sheet and packaging#

Clear rigid PVC uses a benzotriazole UV absorber such as Tinuvin P (UV-P) at 0.1 to 0.5 wt%, or the less volatile Tinuvin 234 where processing runs hot, because a transparent part cannot carry titanium dioxide without losing clarity. Tinuvin P is the only UV absorber in our substance directory with an FDA limit for rigid PVC, capped at 0.25 wt% under 21 CFR 178.2010, but it forms coloured complexes with iron and cobalt ions and is comparatively volatile (1% mass loss at 153 degC). Tinuvin 234 loses 1% of its mass only at 264 degC, which supports its use where extrusion or moulding runs hot. Where absolute colourlessness matters more than volatility, Uvinul 3035 at 0.1 to 1.0 wt% is the cyanoacrylate alternative described above.

Flexible PVC film, plastisols and coated fabrics#

Flexible PVC film, plastisols and coated fabrics use UV absorbers that suit the plasticized matrix, such as UV-531 at 0.1 to 0.7 wt%, liquid octocrylene at 0.1 to 1.0 wt% and Tinuvin 312 at 0.05 to 1.0 wt%. Flexible PVC makes up about 40% of EU PVC consumption, and its plasticizer and stabilizer levels in full are covered on flexible PVC formulations.

No migration or extraction data for UV absorbers from flexible PVC is documented in our source library, so none is stated here. Liquid grades such as Tinuvin 571 and octocrylene are generally preferred for plastisol processing because they disperse into the paste without a separate milling step. UV-531 is also the standard UV absorber in agricultural film, a use covered on its own substance page.

Flexible PVC roofing membranes#

Flexible PVC roofing membranes are the main PVC use for NOR HALS: G. Capocci and M. Hubbard described NOR HALS in flexible PVC roofing in the Journal of Vinyl and Additive Technology in 2005, because their low basicity survives the HCl that deactivates ordinary HALS. Tinuvin 123, a liquid NOR HALS used generally at 0.05 to 0.5 wt% in plastics exposed to acids, is the grade most often named for this use. Tinuvin 123 (NOR HALS) is a liquid aminoether HALS of low basicity, and its full properties and regulatory status are covered on its own substance page.

How Much UV Stabilizer Does PVC Need?#

PVC needs about 0.1 to 1.0 wt% of a UV absorber in mass-stabilized parts, up to 5 wt% in a co-extruded cap layer, or 0.5 to 3.0 phr of rutile TiO2 in opaque pipe, with the level set by transparency, thickness, rigid or flexible matrix and the solar dose at the site of use. A 2024 study by Wiesinger et al., published in Environmental Science & Technology, puts total heat and UV stabilization in PVC at 0.05 to 5 wt% of the compound, a range wide enough to span everything from a lightly loaded mass-stabilized profile to a heavily loaded cap layer.

Four factors set the dose within that range:

• Transparency of the part: an opaque part can carry TiO2, while a clear part is restricted to UV absorbers.
• Section thickness and cap-layer design, since the Beer-Lambert law makes a thin, concentrated surface layer as effective as a thicker, dilute one.
• Rigid versus flexible matrix, which sets which grades are compatible and which dosage range applies.
• Solar dose at the site of use, which formulators account for in trials rather than from a single published figure.

PVC recipes are conventionally written in PHR (parts per hundred resin), while supplier technical data sheets give wt% of the compound; the two units convert directly, since wt% equals the additive's phr divided by the total phr of the recipe, multiplied by 100. As a worked example, 0.5 wt% of a UV absorber in a compound whose full recipe totals 108.03 phr (the PPI TR-2 pipe compound total used above) equals 0.54 phr (0.005 multiplied by 108.03).

Check any conversion between the two units with the PHR to weight percent calculator.

How Do UV Stabilizers Interact with Other PVC Additives?#

UV stabilizers in PVC work inside a package in which the heat stabilizer, the impact modifier and the pigments also decide outdoor performance: the heat stabilizer limits the HCl that attacks HALS, butadiene-based impact modifiers weaken weathering, and dark pigments add heat build-up. Each interaction changes how the UV stabilizer package should be chosen, not just how much of it to use.

Impact modifiers for PVC compares acrylic and MBS chemistries and their weatherability directly, since the choice of impact modifier is one of the most common ways an otherwise well-stabilized PVC compound still fails outdoors. Synergy and antagonism across every additive family, not only UV stabilizers, are mapped under additive interactions, which is the reference to check before combining a new UV package with an unfamiliar heat-stabilizer or pigment system.

How Is the UV Stability of PVC Tested?#

The UV stability of PVC is tested by exposing profiles, sheet or film in xenon-arc or fluorescent-UV cabinets, or outdoors, and tracking yellowness, colour difference and impact strength at set intervals. Accelerated weathering tests describes the full range of cycles and cabinets used across plastics, of which PVC most often uses the two methods below.

Accelerated weathering: xenon arc and fluorescent UV#

Xenon-arc testing to ISO 4892-2 (Method A, cycle 1: 102 minutes of light and 18 minutes of water spray at 0.51 W/(m2 times nm) at 340 nm, with a black-standard temperature of 65 plus or minus 3 degC, a chamber temperature of 38 plus or minus 3 degC and 50 plus or minus 10% relative humidity) is the closest laboratory match to outdoor sunlight for PVC.

None of these laboratory cycles reproduces atmospheric pollution, biological attack or salt-water exposure, and as with unstabilized PVC's thermal chemistry, temperature inside the cabinet often affects the result more than the UV dose alone. The European window-profile standard also sets weathering requirements for PVC-U profiles, though its specific clauses, exposure doses and pass criteria are not documented in our substance directory and are not repeated here.

What to measure: yellowness, colour change and impact#

The three properties that track UV damage in PVC are yellowness index to ASTM E313, colour difference (delta E) to ASTM D2244 and retained impact strength.

• Yellowness index, measured to ASTM E313-20 (reapproved 2025); the withdrawn ASTM D1925 (retired in 1995) is never the current reference.
• Colour difference (delta E), measured to ASTM D2244-25.
• Retained impact strength, tracked at set exposure intervals alongside the two colour measurements above.

No numeric pass or fail criteria, such as a maximum delta E or a minimum retained impact percentage, are documented in our source library for PVC; the end point is set by the relevant product standard or purchase specification rather than by a single universal figure. How the yellowness index is calculated from spectral reflectance data is explained on its own page.

Which UV Stabilizers Are Allowed in Food-Contact and Drinking-Water PVC?#

Food-contact PVC may contain only UV stabilizers listed in Regulation (EU) No 10/2011, within each substance's specific migration limit, and in the US only those cleared for vinyl chloride polymers, such as Tinuvin P at up to 0.25 wt% in rigid PVC under 21 CFR 178.2010. Neither system uses the word "approved": substances are listed and authorised under EU 10/2011, or cleared under 21 CFR 178.2010, not "FDA approved."

EU 10/2011 and FDA limits for UV absorbers in PVC#

Tinuvin P shows how the two systems differ: the EU caps migration of UV-P, UV-326 and UV-329 together at 30 mg/kg of food under group restriction 12, while the US caps UV-P at 0.25 wt% of the rigid PVC itself.

FDA limits are maximum use levels, not recommended dosages. "No entry in our substance directory" means we hold no 21 CFR 178.2010 entry for that grade in PVC; check the current eCFR text before use.

For grades whose FDA entry only covers other polymers, such as UV-531 and Tinuvin 234, this table records "no rigid-PVC limit in our substance directory" rather than "not cleared," since our records extend only to the polymers named in the cited FDA entries. Polymer-by-polymer limits under 21 CFR 178.2010 are explained in detail on that regulation's own page, and EU 10/2011's specific and overall migration limit rules are explained on its page.

Restricted benzotriazoles: UV-328 and UV-329 in PVC#

UV-328 is no longer an option for new PVC compounds: once a common PVC UV absorber at 0.1 to 1.0 wt%, it has been a Stockholm Convention persistent organic pollutant since the eleventh Conference of the Parties in May 2023 (decision SC-11/11), and the EU limit for it as an unintentional trace contaminant falls from 100 mg/kg (from 4 August 2025) to 10 mg/kg (from 4 August 2027) and 1 mg/kg (from 4 August 2029) under Delegated Regulation (EU) 2025/843. UV-328 (Tinuvin 328) was first identified as a Substance of Very High Concern on 17 December 2014 for its PBT and vPvB properties, entered Annex XIV as entry 51 under Regulation (EU) 2020/171 with a sunset date of 27 November 2023, and is not listed in EU 10/2011.

The phased limit lowers the unintentional trace contaminant threshold in three steps: 100 mg/kg from 4 August 2025, 10 mg/kg from 4 August 2027 and 1 mg/kg from 4 August 2029, which pushes recyclers and compounders that process legacy PVC toward tighter UV-328 screening at each step rather than a single cutover date.

UV-329 sits in a different regulatory category from UV-328: it is not a Stockholm Convention substance and it is not on Annex XIV, so it remains a legal choice for new PVC formulations while UV-328 no longer is.

UV-329 is used in rigid and flexible PVC at 0.1 to 0.5 wt% and remains legally usable, but it is not the same regulatory case as UV-328. UV-329 was added to the SVHC Candidate List on 23 January 2024 for its very persistent, very bioaccumulative (vPvB) property alone, it is not on Annex XIV, and it is not on the Stockholm Convention list; a draft Annex XIV recommendation covering it was published on 2 February 2026 with a public consultation that closed on 2 May 2026. UV-329 remains usable but is a Candidate List substance, which triggers article-information duties under REACH rather than an authorisation requirement.

All phenolic benzotriazole UV absorbers used in plastics, including UV-326, are tracked together, with their full SVHC, Annex XIV and Stockholm Convention status, under benzotriazole UV absorbers: SVHC, Annex XIV and POPs status.

Drinking-water PVC pipe#

PVC pipe in contact with drinking water in the EU may use UV absorbers from the European positive list under Directive (EU) 2020/2184, which includes Tinuvin P (entry 0381), Tinuvin 312 (entry 0547) and UV-531 (entry 0368). Tinuvin 234 (entry 0646) and Uvinul 5050 H (entry 0706) also appear on the same positive list. Titanium dioxide has no drinking-water positive-list entry documented in our source library. The EU's implementing positive lists under Implementing Decision (EU) 2024/367 apply from 31 December 2026, after which compliance is assessed against those lists rather than national schemes. US and German drinking-water contact rules are compared on plastic additives in drinking-water contact.

Who Supplies UV Stabilizers for PVC?#

UV stabilizers for PVC are made by 6 major UV-absorber producers, and the same chemistry is sold under up to 5 trade names for a single grade. UV absorbers for PVC come from BASF (Tinuvin, Uvinul, Chimassorb), Syensqo (Cyasorb, spun off from Solvay and listed on 11 December 2023), Songwon (SONGSORB), Clariant (Hostavin), Everlight (Eversorb) and Mayzo (BLS), and the rutile TiO2 from pigment makers such as Chemours (Ti-Pure), Tronox, Kronos, Venator, LB Group and Pangang. BASF announced a capacity expansion for HALS and NOR HALS production on 21 April 2026.

Trade names sharing a CAS number are not a performance-equivalence claim; grades still differ by carrier, purity and physical form.

Buyers should compare grades by CAS number and food-contact status, not by trade name, since two products sold under different brand names can share the identical CAS number while carrying different regulatory listings by country. Plants and grades by company are listed in the directory of UV stabilizer and HALS manufacturers.

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What Other Additives Does Outdoor PVC Need?#

Outdoor PVC needs a complete additive package in which UV stabilizers are only one layer, next to the heat stabilizer, lubricants, an acrylic processing aid and impact modifier, calcium carbonate and, in flexible grades, the plasticizer. The full package for PVC, including the additives outside the scope of this page, is set out on additives for PVC.

Heat stabilizers and UV stability of PVC#

Every PVC compound carries a heat stabilizer at 1 to 5% of the formulation (ECVM), and the choice affects outdoor life: EU profiles run on calcium-zinc or calcium-organic systems, which account for 83% of EU stabilizer use (VinylPlus, June 2023), while US siding and window profiles mainly use butyltin mercaptide. Dibutyltin compounds are restricted to 0.1% tin or less in articles for general public use from 1 January 2012 under REACH Annex XVII entry 20, and lead at 0.1% or more in PVC has been prohibited since 29 November 2024 under entry 63 of Regulation (EU) 2023/923. The full comparison of Ca/Zn, organotin and lead systems is on PVC heat stabilizers.

UV stabilizers for polypropylene and polyethylene compared#

Polypropylene and polyethylene are stabilized mainly with HALS, which take about 70% of world light-stabilizer production, whereas PVC relies on UV absorbers and TiO2 because its HCl deactivates ordinary HALS. In polyethylene, HALS typically run at 0.05 to 0.6 wt% in thick sections and 0.1 to 1.0 wt% in film, while HALS in polypropylene fibres run higher, at 0.1 to 1.4 wt%, reflecting the very different failure modes (crosslinking in PE, chain scission in PP) that HALS interrupt in each polymer.

Grades and dosage by product for the two polyolefins are set out on UV stabilizers for polypropylene and UV stabilizers for polyethylene.

Can PVC be painted for UV protection?#

UV stabilizers for PVC are compounded into the material before extrusion or moulding; paints and coatings applied afterward are a coatings topic outside the scope of this page. This page covers only additives compounded into the PVC itself, not surface treatments applied after the part is formed.

Why does white PVC turn yellow outdoors?#

White PVC turns yellow outdoors because UV-driven HCl loss creates conjugated polyene sequences of 8 or more double bonds, which absorb visible light. Insufficient or exhausted TiO2 and UV-absorber loading is the most common formulation cause, though other discoloration mechanisms unrelated to UV, including pinking and gas fading, are explained under why plastics turn yellow.

How long does PVC last in the sun?#

The outdoor life of PVC depends on its stabilization, colour, thickness and the local solar dose, so no single figure applies: unstabilized clear PVC discolours fastest, while TiO2-pigmented and cap-layered profiles are designed for long outdoor service. No PVC service-life figure is documented in our source library, so none is quoted here; the weathering tests and yellowness measurements described above are the way formulators track this property rather than a single published lifetime.

Are UV stabilizers for PVC toxic?#

Most UV absorbers used in PVC, including Tinuvin P, UV-531, Tinuvin 312 and Tinuvin 234, carry no EU harmonised hazard classification, while UV-328 is a banned persistent organic pollutant and UV-329 is a very persistent, very bioaccumulative (vPvB) Substance of Very High Concern. Tinuvin 234 is currently under ECHA's PBT assessment process, separate from and short of an SVHC listing, and Tinuvin 571 carries a harmonised Aquatic Chronic 4 (H413) classification.

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