Metal deactivators are chelating stabilizers that lock up copper, iron and manganese ions inside a plastic so those ions can no longer split hydroperoxides into the radicals that destroy the polymer. Copper is the reason the family exists, because polyethylene insulation sits directly on a copper conductor for decades at 90 to 105 °C, so which chemistries actually bind it?
Four chemical types answer that question: phenolic hydrazides (Irganox MD 1024), phenolic oxamides (Naugard XL-1), triazole and salicylamide chelators (3-(salicyloylamino)-1,2,4-triazole) and oxalyl bis(hydrazides) (oxalyl bis(benzylidenehydrazide)). Two of those types are primary antioxidants as well, because the two leading grades carry hindered phenol groups on the same molecule as the chelating bridge, which is why the industry calls them special phenolic antioxidants as often as copper inhibitors.
This page covers the metal-catalysed oxidation a metal deactivating agent interrupts, the 4 chemical types with their CAS numbers and trade names, which polymers need one, the legal caps and the missing use level, a 6-step selection route, the interaction with phenolic and thioester antioxidants, the test methods, the EU and US food-contact positions, the 4 producers, and all 3 substances in the directory.
The table below compares the 4 metal deactivator types by chemistry, reference grade, second function, host polymers and food-contact route.
| # | Type | Chemistry | Example grade | Second function | Host polymers | EU / US food-contact route | Substance page |
|---|---|---|---|---|---|---|---|
| 1 | Phenolic hydrazides | bis(hindered phenol propionyl) hydrazine | Irganox MD 1024, SONGNOX 1024, ADK STAB CDA-10, Lowinox MD24 | Primary hindered-phenol antioxidant | PE, XLPE, PP, ABS, POM | EU FCM 675, SML 15 mg/kg; 21 CFR 178.2010 at up to 0.1 % in ABS and POM | Irganox MD 1024 |
| 2 | Phenolic oxamides | oxamide-bridged hindered-phenol propionate | Naugard XL-1 (Antioxidant 697, MD-697) | Primary hindered-phenol antioxidant | PS, HIPS, PP, PE and olefin copolymers | EU FCM 739, no numeric SML; 21 CFR 178.2010 at up to 0.5 % in PS, HIPS and PP | Naugard XL-1 |
| 3 | Triazole and salicylamide chelators | salicylamide triazole | ADK STAB CDA-1 (3-(salicyloylamino)-1,2,4-triazole) | Chelation only | Not specified in our source library | No EU 10/2011 or FDA entry found | 3-(salicyloylamino)-1,2,4-triazole |
| 4 | Oxalyl bis(hydrazides) | oxalyl bis(benzylidenehydrazide) and related hydrazides | No current commercial grade confirmed | Chelation only | Not specified in our source library | No entry found | No page |
Percentages in the food-contact column are legal maxima under the cited instrument, not recommended dosages.
What Is a Metal Deactivator in Plastics?#
A metal deactivator is a plastic additive that chelates transition-metal ions such as copper, iron and manganese inside the polymer, so those ions stop catalysing the breakdown of hydroperoxides into the free radicals that shorten polymer chains. The same function carries six names: metal deactivating agent, MDA, copper inhibitor, copper deactivator, heavy metal deactivator and chelating stabilizer all describe one job, removing a catalyst rather than a radical. Which substances bring those metal ions in? The copper conductor of a cable, the titanium and aluminium residues of the polymerisation catalyst, and the iron and manganese carried by fillers, pigments and recyclate.
Two industries use the term, and the definition above is the polymer one; fuel and lubricant chemistry uses the same words for a different chemistry, which is why the disambiguation sits at the foot of this page. In polymer science, metal deactivators are one of the 43 families of plastic additives catalogued here, filed under the polymer stabilizers next to antioxidants, UV stabilizers, PVC heat stabilizers, acid scavengers and hydrolysis stabilizers.
Metal deactivator or antioxidant: which term is correct?#
Both terms are correct for 2 of the 4 chemistries, because function and chemistry are separate classifications: Irganox MD 1024 and Naugard XL-1 carry hindered phenol groups that scavenge peroxy radicals and a hydrazide or oxamide bridge that chelates copper, so the same molecule is listed in both families. The recorded function of Irganox MD 1024 is primary antioxidant plus metal (copper) deactivator, and of Naugard XL-1 antioxidant plus metal deactivator. Mayzo uses the same reading, calling the class special phenolic antioxidants containing functional groups that enable them to complex with and deactivate metal ions.
The reverse statement is false. Not every metal deactivator is an antioxidant: 3-(salicyloylamino)-1,2,4-triazole carries no phenol group in its record and has a single function, metal deactivation. The distinction matters in formulation, because a hybrid grade counts toward the phenolic load of a package while a pure chelator does not, which is why both hybrids also appear among the antioxidants for plastics.
The table below separates the three stabilizer functions that compounders most often confuse.
| Criterion | Metal deactivator | Primary antioxidant | Acid scavenger |
|---|---|---|---|
| What it removes | Metal ions, by chelation | Free radicals, by hydrogen donation | Acidic residues, by neutralisation |
| Target species | Cu, Fe, Mn and Ti ions | ROO• and RO• radicals | HCl and catalyst acids |
| Effect if absent | Metal-catalysed hydroperoxide decomposition accelerates oxidation | The radical chain runs uncontrolled | Acid attack on the polymer and corrosion of the tool |
| Typical chemistry | Hydrazides, oxamides, triazoles | Hindered phenols, aromatic amines | Metal stearates, hydrotalcite, basic oxides |
| Does it stabilize on its own | No: ADEKA states that a heavy metal deactivator has no stabilizing effect of its own, so a thermal stabilizer is still needed | Yes, against radical attack | No, against oxidation |
| Site family | Metal deactivators | Antioxidants for plastics | Acid scavengers and catalyst neutralizers |
Why Copper Attacks Polyethylene: Metal-Catalysed Oxidation#
Polyethylene in contact with copper oxidises far faster than the same polyethylene on its own, because copper ions split the hydroperoxides formed during processing and service into two fresh radicals instead of letting them decompose slowly. Thermo-oxidative degradation of a polyolefin runs as a chain: an alkyl radical meets oxygen to give a peroxy radical, the peroxy radical abstracts hydrogen to give a hydroperoxide, and that hydroperoxide is the reservoir the chain draws on.
A transition-metal ion turns the reservoir into an accelerator. Every hydroperoxide the polymer forms becomes two radicals instead of one slow decomposition, so the induction period collapses and the failure mode follows the polymer: polypropylene chain-scissions, raising melt flow rate, while polyethylene crosslinks and forms gels. Both end the same way for an insulation wall, in embrittlement and cracking.
Which metals catalyse polymer degradation, and where do they come from?#
Five metals matter in plastics: copper above all, then iron and manganese, and the titanium and aluminium left behind by polymerisation catalysts. Copper leads because it is the one metal a polymer is deliberately pressed against for its whole service life. Iron and manganese arrive as contamination, while titanium and aluminium arrive as catalyst residue, which is why they are present in polyolefins that never see a metal part.
The 4 routes by which catalytic metal ions enter a plastic compound are listed below.
- Conductor contact: a copper or copper-alloy conductor pressed against polyethylene or crosslinked polyethylene insulation for the life of the cable.
- Catalyst residue: titanium and aluminium left in the resin by the polymerisation catalyst, present before any compounding step.
- Fillers and pigments: mineral and colorant additions that can carry iron and manganese into the melt.
- Recyclate contamination: metal picked up in collection, shredding and separation, including conductor fragments in cable recyclate.
No threshold in parts per million exists for how much copper, iron or manganese triggers accelerated oxidation, so no trigger level is published here.
Why is copper a stabilizer in nylon but a poison in polyethylene?#
Copper is deliberately added to nylon and deliberately kept out of polyethylene: a copper-halide system stabilizes polyamide for long-term heat, while the same ion without a halide partner catalyses oxidation in a polyolefin. The classic copper-halide route, claimed by DuPont in US patent 2,705,227, uses 0.001 to 0.03 wt% copper, preferably 0.005 to 0.01 wt%, with 0.1 to 5 wt% of a halide, and commercial copper-salt systems are rated to about 180 °C, which is why the copper-halide route is standard among additives for nylon.
The halide makes the difference and carries its own cost. Halide ions corrode metal parts and lower the comparative tracking index, so halogen-free polyamide stabilizers such as BRUGGOLEN TP-H2062 and TP-H2217 exist for electrical parts. In food contact the route is capped twice: copper iodide is FCM 412 under iodine group restriction 6 with an SML(T) of 1 mg/kg as iodine, and copper carries an Annex II limit of 5 mg/kg. The copper and halide levels are set out on heat stabilizers for nylon.
How does a metal deactivator work? Chelation of the metal ion#
A metal deactivator works in 4 steps: it meets a free metal ion inside the melt or the solid polymer, its hydrazide or oxamide donor atoms close a ring around that ion, the chelated ion loses its ability to split hydroperoxides, and any hindered phenol on the same molecule continues to trap radicals separately. The steps are set out below in the order they occur.
- Encounter the ion. The dispersed deactivator meets a copper, iron, manganese or titanium ion inside the polymer matrix.
- Close the chelate ring. The nitrogen and oxygen donor atoms of the hydrazide or oxamide bridge coordinate to the ion from two or more positions at once, which distinguishes chelation from simple complexation.
- Block the catalytic cycle. The bound ion no longer shuttles between oxidation states, so the redox route that produced two radicals from one hydroperoxide is closed.
- Keep scavenging radicals. On hybrid grades the hindered phenol at each end donates hydrogen to peroxy radicals, independently of any metal ion.
Chelation alone does not make a compound stable. ADEKA states in its polymer additives FAQ that a heavy metal deactivator has no stabilizing effect of its own, so a thermal stabilizer is still required, and BASF describes Irganox MD 1024 as a metal deactivator and primary phenolic antioxidant because it carries both jobs. No chelate stoichiometry, stability constant or ring size is published here, because none is established; the full cycle is set out on polymer oxidation and antioxidant mechanisms.
4 Types of Metal Deactivators for Plastics#
Metal deactivators for plastics fall into 4 chemical types: phenolic hydrazides, phenolic oxamides, triazole and salicylamide chelators, and oxalyl bis(hydrazides). The order follows commercial weight and evidence depth, from the grade with a numeric EU migration limit and a documented cable history down to the chemistry that appears in the literature without a confirmed commercial grade. Hydrazides and oxamides dominate the family, and both are frequently hybridised with a hindered phenol, the structural reason the two leading grades are dual-function molecules.
1. Phenolic hydrazides: Irganox MD 1024 and its equivalents#
Phenolic hydrazides are bis(hindered phenol) propionyl hydrazines that chelate copper and scavenge radicals at the same time, and the reference grade is Irganox MD 1024 (CAS 32687-78-8), a white powder melting at 221 to 232 °C. Its systematic name is 1,2-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, EC 251-156-3, formula C34H52N2O4, molecular weight 552.8 g/mol. Songwon reports 5 % weight loss at about 307 °C by thermogravimetric analysis, 10 % at 319 °C and 50 % at 359 °C, far above polyolefin melt temperatures.
The same substance sells under 5 names: Irganox MD 1024 by BASF, SONGNOX 1024 by Songwon, ADK STAB CDA-10 by Adeka, Lowinox MD24 by SI Group, and Antioxidant 1024 in numeric trade practice. BASF describes the grade as a metal deactivator and primary phenolic antioxidant for telecommunication wire and cable applications with excellent extraction resistance. Both food-contact routes are documented: EU FCM substance 675, reference number 38800, with a specific migration limit of 15 mg/kg, and 21 CFR 178.2010 at up to 0.1 % in ABS and in polyoxymethylene, with adhesives under 21 CFR 175.105. It is registered under REACH with 9 active full dossiers, and was not found on the Candidate List, Annex XIV, Annex XVII or the POPs list in the sources checked.
2. Phenolic oxamides: Naugard XL-1#
Phenolic oxamides are oxamide-bridged hindered phenol propionates, and the one grade in this class is Naugard XL-1 (CAS 70331-94-1), which SI Group also sells under the number Antioxidant 697. Its systematic name is 2,2'-oxamidobis[ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], EC 274-572-7, formula C40H60N2O8, molecular weight 696.9 g/mol, the heaviest of the 3 documented substances. Each of the two hybrids is recorded as the alternative to the other, so they substitute across polymers.
Its US clearances are food-type dependent and must be read in full rather than rounded into one number. Under 21 CFR 178.2010 the grade is listed at up to 0.5 % in polystyrene and rubber-modified polystyrene, at up to 0.5 % in polypropylene under items 1.1 to 1.3, and at up to 0.5 % in polyethylene and olefin copolymers for food types I, II, IV-B, VI, VII-B and VIII, dropping to 0.1 % for types III, IV-A, V, VII-A and IX unless the copolymer is propylene-majority. In the EU it is FCM substance 739, reference number 70000, without a numeric specific migration limit. It is registered under REACH with 3 active dossiers, with PubChem-aggregated self-classifications of H412 and H413.
3. Triazole and salicylamide chelators: ADK STAB CDA-1#
Triazole and salicylamide chelators are small nitrogen-rich molecules that bind metal ions without carrying a phenol group, and the one grade in our source library is 3-(salicyloylamino)-1,2,4-triazole (CAS 36411-52-6), sold by Adeka as ADK STAB CDA-1. It also appears as 2-hydroxy-N-(1H-1,2,4-triazol-5-yl)benzamide, as N-(1,2,4-triazol-3-yl)salicylamide and, in PubChem, as MARK 1475. Its EC number is 253-021-4, its formula is C9H8N4O2 and its molecular weight is 204.19 g/mol, roughly a third of the two hybrid grades.
The substance is registered under REACH with 1 active full dossier, and no EU 10/2011 entry, no FDA entry and no POPs entry was found in the sources checked; PubChem aggregates supplier self-classifications of H302 and H304. No polymer list, no dosage and no migration or extraction data exist for this grade, so no migration behaviour is claimed for it in either direction. The ADEKA polymer additives FAQ names CDA-1 and CDA-10 together as its heavy metal deactivators.
4. Oxalyl bis(hydrazides) and other hydrazide chemistries#
Oxalyl bis(hydrazides) are the fourth metal deactivator chemistry named in the literature, represented by oxalyl bis(benzylidenehydrazide) (CAS 6629-10-3), and no current commercial plastics grade of this class is confirmed. The class sits with the hydrazides, alongside the phenolic hydrazide of type 1, and the shared feature is the hydrazide nitrogen set that closes the chelate ring around the metal ion.
Whether any producer currently offers a grade of this class is an open verification item, so no supplier, trade name, dosage or regulatory status is stated for it. The patent literature keeps the route alive: US 8,063,126 B2, "Heavy metal deactivator/inhibitor for use in olefinic polymers", claims polymeric hydrazine derivatives for olefin polymers, named here as literature that exists rather than as a source of values.
Which Plastics and Applications Need a Metal Deactivator?#
A metal deactivator belongs in any compound that spends its service life against metal or carries metal contamination: polyethylene and crosslinked polyethylene insulation on copper conductors first, then recycled polyolefins, then filled and pigmented compounds that bring their own metal ions. Food-contact grades add a fourth case, decided by the polymer that is cleared rather than by the metal present: Irganox MD 1024 is listed for ABS and polyoxymethylene, Naugard XL-1 for polystyrene, rubber-modified polystyrene, polypropylene and polyethylene.
The table sets out where a metal deactivator is used, which metal is present, and which additive package is recorded for that case.
| Application | Polymer | Metal source | Additive package named in our source library | Regulatory note |
|---|---|---|---|---|
| Telecommunication and power cable insulation | PE, XLPE | Copper conductor | Metal deactivator phenol plus thioesters (MD 1024, Santonox R, DSTDP); XLPE uses Irganox 1035 with MD 1024 | Peroxide-crosslinked compounds need antioxidants that do not interfere with the peroxide |
| Cable recyclate in new compounds | PP with XLPE from end-of-life cable | Residual copper from the conductor | Irganox MD 1024 | Mechanical properties retained through 6,000 h of accelerated ageing at 105 °C (ACS Applied Polymer Materials review, 2024) |
| Food-contact ABS and POM | ABS, POM | Processing and contamination | Irganox MD 1024 | 21 CFR 178.2010 at up to 0.1 % |
| Food-contact PS, HIPS, PP and PE | PS, HIPS, PP, PE | Processing and contamination | Naugard XL-1 | 21 CFR 178.2010 at up to 0.5 %, food-type dependent |
| Recycled polyolefins generally | rPP, rPE | Metal contaminants carried in with the feedstock | Restabilization blends of phenol and phosphite at 0.1 to 0.3 wt%, with a metal deactivator where copper is present | No dedicated instrument |
Wire and cable: polyethylene and XLPE insulation over copper#
Cable insulation is the reason this additive family exists: a polyethylene or crosslinked polyethylene wall sits directly on copper for decades at 90 to 105 °C, which is the exact combination of metal contact, heat and oxygen that metal-catalysed oxidation needs. Emergency operation takes the same wall to 130 to 140 °C and a short circuit to 250 °C for about half a second, and the whole package is compared on additives for wire and cable compounds.
Crosslinking adds a second constraint. Peroxide vulcanisation runs above 180 °C for about 5 minutes, and peroxide-crosslinked compounds need antioxidants that do not interfere with the peroxide, which narrows the stabilizer choice before the copper question is asked. Hot set to IEC 60811-507 verifies the crosslink state, with elongation under load limited to 175 %.
For crosslinked polyethylene the recorded pairing is the thio-phenol Irganox 1035 with Irganox MD 1024, and the wider cable package is a metal deactivator phenol plus thioethers, naming MD 1024, Santonox R and DSTDP. The phenol and phosphite side of that package is covered by antioxidants for polyethylene. No metal deactivator loading for cable insulation is published here, because no verified value exists in the public record.
Recycled polyolefins and cable recyclate#
Recycled polyolefins are the second case for a metal deactivator, because cable recyclate brings the copper with it: in polypropylene blends containing crosslinked polyethylene from end-of-life cables, Irganox MD 1024 can keep mechanical properties through 6,000 hours of accelerated ageing at 105 °C, as a 2024 review in ACS Applied Polymer Materials records. Copper is one of the 3 contaminant classes dealt with in additives for recycled plastics, alongside residual antioxidant loss and oxidised chain ends.
A recyclate arrives in worse condition than virgin resin in three measurable ways, described by Rudolf Pfaendner in Polymer Degradation and Stability 203 (2022) 110082: less residual antioxidant, more carbonyl and hydroperoxide groups, and more metal contamination. The first two raise the radical load; the third supplies the catalyst that multiplies it.
Restabilization answers the first two. Phenol and phosphite blends are dosed at 0.1 to 0.3 wt% for recyclate, a range that belongs to the antioxidant package rather than to the metal deactivator, and those blends are set out on restabilization of recycled plastics.
Filled, pigmented and metal-contact compounds#
Metal ions also arrive without a conductor: polymerisation catalyst residues leave titanium and aluminium behind, and fillers, pigments and process contamination can carry iron and manganese into the compound. Which filler or pigment carries which metal is not recorded here, so no mineral or colorant is named as a proven metal source.
The consequence is polymer-specific. In polypropylene the metal-accelerated chain ends in scission, so melt flow rate rises between one processing pass and the next; in polyethylene it ends in crosslinking and gel formation, which shows up as surface defects and lost elongation. ADEKA states that a heavy metal deactivator has no stabilizing effect of its own, so it is added alongside a thermal stabilizer rather than instead of one.
How Much Metal Deactivator Does a Compound Need? Dosage, Legal Caps and Masterbatch#
No verified typical use level for a metal deactivator in cable insulation exists in the public record, so the only defensible numbers are the legal ceilings: 0.1 % for Irganox MD 1024 in food-contact ABS and polyoxymethylene, and 0.5 % for Naugard XL-1 in polystyrene and polypropylene under 21 CFR 178.2010. Those percentages are composition caps, not recommendations, and paragraph (a) limits any listed substance to the amount reasonably required for its technical effect, so the legal ceiling and the formulating level are different numbers by design.
The EU route sets no dosage at all. Regulation (EU) No 10/2011 controls Irganox MD 1024 through a specific migration limit of 15 mg/kg rather than a composition cap and lists Naugard XL-1 without a numeric limit, so compliance is demonstrated on the finished article by migration testing. The nearest published range, 0.1 to 0.3 wt% for phenol and phosphite restabilization blends in recyclate, belongs to the antioxidant family and is not transferable to this one.
The table lists every legal limit recorded for the 3 documented substances, with the instrument and the type of limit in each row.
| Substance | Instrument | Polymer or scope | Limit | Type of limit |
|---|---|---|---|---|
| Irganox MD 1024 | Regulation (EU) No 10/2011, FCM 675, Ref 38800 | Plastic food-contact materials | SML 15 mg/kg, fat reduction factor applicable | Migration |
| Irganox MD 1024 | 21 CFR 178.2010 | ABS | 0.1 % | Composition cap |
| Irganox MD 1024 | 21 CFR 178.2010 | POM | 0.1 % | Composition cap |
| Irganox MD 1024 | 21 CFR 175.105 | Adhesives | As listed | Composition |
| Naugard XL-1 | Regulation (EU) No 10/2011, FCM 739, Ref 70000 | Plastic food-contact materials | No numeric SML, fat reduction factor not applicable | Listed without a numeric SML |
| Naugard XL-1 | 21 CFR 178.2010 | PS and rubber-modified PS | 0.5 % | Composition cap |
| Naugard XL-1 | 21 CFR 178.2010 | PP, items 1.1 to 1.3 | 0.5 % | Composition cap |
| Naugard XL-1 | 21 CFR 178.2010 | PE and olefin copolymers, food types I, II, IV-B, VI, VII-B, VIII | 0.5 % | Composition cap |
| Naugard XL-1 | 21 CFR 178.2010 | PE and olefin copolymers, other food types | 0.1 % | Composition cap |
| 3-(Salicyloylamino)-1,2,4-triazole | None found | Not applicable | No EU or US food-contact entry found | No entry |
Where Regulation (EU) No 10/2011 gives no numeric SML, the generic limits still apply: an overall migration limit of 10 mg/dm2 and, for substances without a specific limit, a generic SML of 60 mg/kg. Values reflect the consolidated text of 16 March 2025.
All 3 substances are powders, dosed during plastic compounding or supplied as a masterbatch on a carrier resin. Irganox MD 1024 melts at 221 to 232 °C, above polyolefin melt temperatures, so it disperses as a solid phase distributed by shear rather than dissolved, which is the argument for a masterbatch in thin-wall insulation.
A masterbatch also fixes the accuracy problem, because metal deactivators are minor components, and the conventions for letting down minor additives are on additive dosage levels in plastics. This reference publishes a use-level range once a producer datasheet confirms one; until then the legal ceilings above are the only numbers stated.
How Do You Select a Metal Deactivator? 6 Steps#
Select a metal deactivator in 6 steps: identify the metal and where it comes from, match the host polymer to a cleared grade, check the processing temperature against the grade's thermal data, screen the food-contact route in every target market, check the rest of the stabilizer package, then set the level under the legal ceiling and confirm it by oven ageing.
- Identify the metal and its source. Establish whether the compound faces a copper conductor, a catalyst residue, a filler or pigment, or recyclate contamination.
- Match the host polymer to a cleared grade. Irganox MD 1024 has documented use in PE, XLPE, PP, ABS and POM; Naugard XL-1 in PS, HIPS, PP, PE and olefin copolymers; the triazole chelator has no polymer record here.
- Check the processing window against the thermal data. Irganox MD 1024 melts at 221 to 232 °C and loses 5 % of its mass at about 307 °C; a grade without published thermal data should be tested first.
- Screen the food-contact route in each market. Check an EU application against the FCM number and its migration limit, a US application against the 21 CFR 178.2010 entry for that polymer and food type.
- Check the rest of the stabilizer package. A hybrid grade already contributes a hindered phenol, so the phenol level should be recalculated rather than added to.
- Fix the level under the legal ceiling and confirm it. Set the level below the applicable composition cap and verify it by oxidative-induction time and oven ageing.
The same 7-step logic behind how to select plastic additives applies here, with the metal identification step added at the front.
How Do Metal Deactivators Work with Antioxidants and Other Stabilizers?#
A metal deactivator is never the whole package: in crosslinked polyethylene cable compounds it sits next to a thio-phenol such as Irganox 1035 and a thioester such as DSTDP, because chelation removes the catalyst while the phenol and the thioester handle the radicals and the hydroperoxides. The recorded wire and cable package is a metal deactivator phenol plus thioethers, naming Irganox MD 1024, Santonox R and DSTDP. Two combinations are documented as working:
- Works with a thio-phenol: Irganox 1035 with Irganox MD 1024 in crosslinked polyethylene cable formulations.
- Works with thioesters: DSTDP and Santonox R alongside a metal deactivator phenol, where thiosynergists act at long-term heat ageing around 100 to 150 °C rather than in the melt.
Two constraints limit what else the package can carry:
- Watch the phenol budget: Irganox MD 1024 and Naugard XL-1 already carry hindered phenol groups, so both count toward the phenolic load rather than sitting outside it.
- Watch the thioester and HALS pair: thioesters antagonise hindered amine light stabilizers, so a weathered jacket needing HALS cannot rely on the thioester half of this package.
Peroxide crosslinking adds a third constraint set by the cure chemistry, because peroxide-cured compounds need antioxidants that do not interfere with the peroxide. No synergy or antagonism beyond the pairs above is claimed here, and the full set of additive interactions is catalogued separately.
How Is Metal Deactivator Performance Tested? OIT, Oven Ageing and Copper Contact#
Metal deactivator performance is measured as retained oxidation resistance in contact with the metal, most often by oxidative-induction time to ASTM D3895-19 or ISO 11357-6 at 190 to 220 °C in oxygen, backed by oven ageing to embrittlement and by melt flow rate before and after ageing. Those two standards are not technically equivalent, so a result carries the method it was measured by. Where the OIT of a well-stabilized compound exceeds 30 minutes, high-pressure OIT to ASTM D5885 at 3.4 MPa oxygen and 150 °C shortens the experiment. The method index for testing plastic additives lists every standard used here.
No copper-plate, copper-mesh or copper-wire ageing method is documented in our source library, although a metal-contact test is the obvious one for this family, so no target value is published. The table lists the established methods, their conditions and the effect a metal deactivator produces in each.
| What it measures | Standard | Condition | What a metal deactivator changes |
|---|---|---|---|
| Oxidative induction time (OIT) | ASTM D3895-19, ISO 11357-6 | 190 to 220 °C in oxygen | Longer time to the oxidation exotherm when a catalytic metal is present |
| High-pressure OIT | ASTM D5885 | 3.4 MPa O2, 150 °C | Used when OIT exceeds 30 minutes |
| Long-term heat aging to embrittlement | ASTM D3012, ISO 188, UL 746B | Days at a set temperature | Later embrittlement in metal contact |
| Melt flow rate | ISO 1133-1, ASTM D1238-26 | PE 190 °C / 2.16 kg, PP 230 °C / 2.16 kg | Smaller MFR shift after processing and ageing |
| Hot set (crosslinked insulation) | IEC 60811-507 | Maximum 175 % elongation | Confirms the crosslink state is unaffected |
| Specific migration (food contact) | EU 10/2011 migration testing | Food simulants | Confirms compliance with the SML |
How Are Metal Deactivators Regulated?#
Metal deactivators are regulated in 3 layers: chemical registration under Regulation (EC) No 1907/2006 in the EU and the Toxic Substances Control Act in the United States, food-contact positive lists under Regulation (EU) No 10/2011 and 21 CFR 178.2010, and the general product rules of whatever article the compound ends up in. The layer model is explained under plastic additive regulations.
All 3 documented substances sit in the first layer as registered rather than restricted substances. Irganox MD 1024 carries 9 active full dossiers, Naugard XL-1 carries 3, and 3-(salicyloylamino)-1,2,4-triazole carries 1. None was found on the Candidate List, Annex XIV or Annex XVII in the sources checked on 22 September 2026.
The United States adds a volume datapoint rather than a restriction: EPA Chemical Data Reporting, published through PubChem, places the 2023 US production and import volume of Irganox MD 1024 at 850,000 to under 1,000,000 lb. Registration status is what REACH and plastic additives tracks, re-verified at each ECHA update.
EU food contact: Regulation (EU) No 10/2011 FCM numbers and SMLs#
In the EU, Irganox MD 1024 is authorised for plastic food-contact materials as FCM substance 675 with a specific migration limit of 15 mg/kg, and Naugard XL-1 as FCM substance 739 without a numeric limit of its own. Irganox MD 1024 carries reference number 38800 with the fat reduction factor applicable; Naugard XL-1 carries reference number 70000 with the factor not applicable. No entry was found for 3-(salicyloylamino)-1,2,4-triazole, so it is not on the Union list.
A missing numeric limit is not an absence of limits. Where Regulation (EU) No 10/2011 sets no specific migration limit for a listed substance, the generic SML of 60 mg/kg applies, and the overall migration limit of 10 mg/dm2 applies to the article regardless. The Union list mechanism is explained on EU 10/2011, and these values were verified against the consolidated text of 16 March 2025.
Copper is regulated from the other direction in the same instrument. Annex II limits copper migration from a plastic food-contact article to 5 mg/kg, so a compound holding both a copper source and a copper chelator has two numbers to satisfy. All specific migration limits (SML) for additives are tabulated together.
US food contact: 21 CFR 178.2010 limits by polymer#
In the United States, both hybrid metal deactivators are listed in 21 CFR 178.2010: Irganox MD 1024 at up to 0.1 % in ABS and polyoxymethylene, and Naugard XL-1 at up to 0.5 % in polystyrene, rubber-modified polystyrene and polypropylene. That section is titled "Antioxidants and/or stabilizers for polymers", and its structure explains why one percentage is never the whole answer: paragraph (a) limits use to the amount reasonably required, and paragraph (b) carries a table whose entries are specific to the polymer, the food type and the conditions of use.
Naugard XL-1 shows the food-type dependence most clearly. In polyethylene and olefin copolymers it is listed at up to 0.5 % for food types I, II, IV-B, VI, VII-B and VIII and at 0.1 % for the remaining types, unless the copolymer is propylene-majority. Irganox MD 1024 adds adhesives under 21 CFR 175.105. The whole substance table of 21 CFR 178.2010 is reproduced separately.
A listing there is a condition-bound clearance for a use, not an approval of the substance, so neither grade is correctly described as FDA approved. The clearance holds only within the polymer, food type and conditions written into its entry, and how clearances work under the FDA food contact rules is explained separately.
Who Makes Metal Deactivators? Suppliers and Trade Names#
Four producers hold the named metal deactivator grades: BASF (Irganox MD 1024), Songwon (SONGNOX 1024), Adeka (ADK STAB CDA-10 and CDA-1) and SI Group (Naugard XL-1, Lowinox MD24). All four sell the deactivator inside a wider antioxidant portfolio, and Songwon describes itself as the world's second-largest polymer stabilizer maker, a claim that belongs to the company. Company profiles sit in the directory of plastic additive manufacturers and suppliers.
The table lists the 4 producers with their headquarters, brand lines and recorded grades.
| Producer | Headquarters | Brand line | Metal deactivator grades in our source library | Supplier page |
|---|---|---|---|---|
| BASF | Ludwigshafen, Germany | Irganox | Irganox MD 1024 | BASF |
| Songwon | Ulsan, South Korea | SONGNOX | SONGNOX 1024 | Songwon |
| Adeka | Tokyo, Japan | ADK STAB | ADK STAB CDA-10, ADK STAB CDA-1 | Adeka |
| SI Group | The Woodlands, Texas, USA | LOWINOX, NAUGARD | Naugard XL-1, Lowinox MD24 | SI Group |
Grades listed are those recorded in our source library. Equivalents sold under numeric names such as Antioxidant 1024 and Antioxidant 697 are the same substances by CAS number.
No market size is published for metal deactivators as a segment, because none exists in the sources checked; Mordor Intelligence puts the parent plastic antioxidant market at USD 5.41 bn for 2025, a figure covering antioxidants as a whole. The same 4 producers appear among the polymer antioxidant manufacturers and suppliers.
Complete List of Metal Deactivator Substances (3 Pages)#
The complete list of metal deactivator substances below gives all 3 grades documented in this reference, with CAS and EC numbers, chemical class, second function and food-contact status. The values repeat the sections above rather than adding anything new, and every empty field reads "no entry found" rather than being left blank.
| Substance | CAS | EC | Chemical class | Second function | EU 10/2011 | 21 CFR 178.2010 | REACH |
|---|---|---|---|---|---|---|---|
| Irganox MD 1024 | 32687-78-8 | 251-156-3 | Hindered phenol hydrazide | Primary antioxidant | FCM 675, Ref 38800, SML 15 mg/kg, FRF applicable | 0.1 % ABS, 0.1 % POM; adhesives under 175.105 | Registered, 9 active full dossiers |
| Naugard XL-1 | 70331-94-1 | 274-572-7 | Hindered phenol oxamide | Primary antioxidant | FCM 739, Ref 70000, no numeric SML, FRF not applicable | 0.5 % PS and rubber-modified PS; 0.5 % PP items 1.1 to 1.3; 0.5 % or 0.1 % PE and olefin copolymers by food type | Registered, 3 active dossiers |
| 3-(salicyloylamino)-1,2,4-triazole | 36411-52-6 | 253-021-4 | Salicylamide triazole | No entry found | No entry found | No entry found | Registered, 1 active full dossier |
Each grade has a full record in the plastic additives database, with molecular formula, physical data, GHS entries and the full regulatory matrix.
How Do Metal Deactivators Fit Among the Other Polymer Stabilizers?#
Metal deactivators are 1 of the 6 stabilizer families used in plastics, and the difference between them is simply what each one removes: radicals, hydrogen chloride, ultraviolet light, acids, metal ions or water. Antioxidants take the radicals, and the two hybrid metal deactivator grades belong to that family as well. UV stabilizers for plastics remove the ultraviolet energy before it starts a radical chain at the surface.
The remaining three split the chemical attackers. PVC heat stabilizers neutralise the hydrogen chloride that polyvinyl chloride releases on heating, and acid scavengers neutralise the acidic residues left by polymerisation catalysts. Water is the last attacker, and hydrolysis stabilizers deal with it in polyesters and polyurethanes. Metal deactivators are the only one of the six that removes a catalyst rather than a reactant or an energy input.
Is a metal deactivator the same as an acid scavenger or a catalyst neutralizer?#
No: an acid scavenger neutralises the acidic residues a catalyst leaves behind, while a metal deactivator chelates the metal ion itself, and a compound with Ziegler-Natta residues can need both. Both families answer the same problem, what the polymerisation catalyst leaves in the resin, which is where the confusion starts. The species they act on differ: an acid scavenger reacts with hydrogen chloride and other acidic residues using metal stearates, hydrotalcite-type layered double hydroxides or basic oxides, while a metal deactivator closes a chelate ring around the metal ion.
Their failure modes differ in the same way. Without an acid scavenger a compound suffers acid attack and tool corrosion; without a metal deactivator it suffers accelerated hydroperoxide decomposition and early embrittlement. That first job belongs to acid scavengers and catalyst neutralizers, a separate family in this reference.
Is a fuel or lubricant metal deactivator the same additive?#
No: the metal deactivators sold for jet fuel and lubricating oil are salen-type compounds such as N,N'-disalicylidene-1,2-propanediamine (CAS 94-91-7), a different chemistry from the hydrazides and oxamides used in plastics, even though both work by chelating metal ions. The two industries share a name and a principle, and nothing else. The fuel-side substance is a Schiff base formed from salicylaldehyde and a diamine, and PubChem notifications for it include H360, a classification that attaches to none of the 3 plastics substances documented here.
The encyclopedic article titled "Metal deactivator" describes the fuel and oil additives only; the polymer definition sits in the article on polymer stabilizers, which is why a search for the bare term returns refinery, pipeline and metalworking-fluid suppliers ahead of any plastics page. For a compounder the consequence is simple: a fuel-grade metal deactivator is not a substitute for a polymer-grade one, it carries no EU 10/2011 or 21 CFR 178.2010 position for plastics, and the fuel application is outside the scope of this reference.
Are metal deactivators restricted, and what happens to them in recycling?#
None of the 3 metal deactivator substances documented here appears on the REACH Candidate List, Annex XIV, Annex XVII or the POPs list in the sources checked on 22 September 2026, and none carries a harmonised hazard classification. The hazard statements against them, H412 for Irganox MD 1024, H412 and H413 for Naugard XL-1, and H302 and H304 for 3-(salicyloylamino)-1,2,4-triazole, are PubChem aggregations of supplier self-classifications rather than classifications agreed under Regulation (EC) No 1272/2008. None appears on the SVHC Candidate List in the sources checked, and that statement is re-verified at each ECHA update.
In recycling the family sits on the solution side rather than the problem side. Copper contamination is one reason cable recyclate degrades faster than virgin resin, and Irganox MD 1024 is the grade recorded as answering it in polypropylene blends containing crosslinked polyethylene from end-of-life cables. That makes a metal deactivator part of the restabilization package for metal-contaminated feedstock, and the wider recyclate question belongs to design for recycling.