Antioxidant 405 is a high-performance aromatic amine antioxidant used to protect polymers, elastomers, polyols, adhesives, and selected lubricant systems against oxidative and thermal degradation. Its main value is strong heat-aging protection, relatively low volatility, and effective stabilization under demanding processing or service temperatures. It is particularly relevant in rubber compounds such as neoprene, nitrile rubber, EPDM, HNBR, and acrylic rubber, while also finding use in polyolefins, styrenics, polyamides, polyurethane-related systems, hot-melt adhesives, and other industrial formulations. The correct use level and stabilizer combination depend on the polymer, processing temperature, color requirements, regulatory constraints, and expected service life.
Chemically, Antioxidant 405 is commonly identified as 4,4′-bis(alpha,alpha-dimethylbenzyl)diphenylamine, CAS No. 10081-67-1. PubChem lists the molecular formula as C30H31N and a molecular weight of about 405.6 g/mol. Because it belongs to the aromatic amine antioxidant family, it is designed primarily to interrupt oxidative chain reactions and help slow the property loss that can occur when polymers are exposed to heat and oxygen.
Product Introduction
Polymer oxidation is a chain reaction. Heat, shear, residual catalyst species, oxygen, light, and long-term service conditions can create reactive radicals inside a polymer. Once these radicals react with oxygen, they can form peroxy radicals and hydroperoxides, which may accelerate degradation. The visible or measurable consequences can include embrittlement, loss of tensile properties, viscosity change, cracking, discoloration, reduced flexibility, and shorter service life.
Antioxidant 405 is used to slow this degradation pathway. As an aromatic amine antioxidant, it can act as a chain-breaking stabilizer by reacting with radical species before those radicals continue the oxidation cycle. In practical formulation work, the result can be improved retention of mechanical properties and better resistance to thermal-oxidative aging, especially in systems exposed to elevated temperatures.
The product is also known in the market under related naming conventions such as KY-405, and some technical literature identifies the same chemical substance as Antioxidant 445. Naming can vary by producer, so buyers should confirm the CAS number, chemical name, purity specification, physical form, and technical data sheet rather than relying only on a trade name.
| Property | Typical technical identification |
| Chemical family | Aromatic amine antioxidant |
| Chemical name | 4,4′-Bis(alpha,alpha-dimethylbenzyl)diphenylamine |
| CAS number | 10081-67-1 |
| Molecular formula | C30H31N |
| Molecular weight | Approximately 405.6 g/mol |
| Typical physical form | White to off-white crystalline powder or crystals, depending on grade |
| Main functional role | Thermal-oxidative stabilization of polymers and related industrial systems |
Key Features
Strong thermal-oxidative protection
One of the main reasons formulators select Antioxidant 405 is its ability to protect materials exposed to heat and oxygen. Supplier technical literature describes it as providing excellent heat resistance and good oxidation resistance in a broad range of natural and synthetic polymers. This is valuable in applications where repeated thermal exposure, curing, processing, or long service temperatures can gradually damage the polymer structure.
Low volatility for demanding processing conditions
Low volatility is important because an antioxidant that evaporates, migrates, or is lost during high-temperature processing cannot provide reliable long-term protection. Antioxidant 405 is valued for relatively low volatility compared with many conventional amine antioxidants. That characteristic can support better retention of the stabilizer during processing and thermal aging, particularly in elastomer and engineering-polymer applications.
Broad compatibility across polymer families
Technical data from suppliers reports use in neoprene, nitrile rubber, EPDM, HNBR, acrylic rubber, polyolefins, styrenics, polyamides, polyols, polyurethane foams, hot-melt adhesives, and lubricants. This does not mean one formulation can be transferred unchanged between all these systems. Compatibility, solubility, cure behavior, color, migration, and final regulatory requirements must still be evaluated in the actual formulation.
Useful synergy with complementary antioxidants
Industrial stabilization rarely depends on one additive alone. A chain-breaking amine antioxidant can be paired with other stabilizer classes to address multiple degradation pathways. For example, phenolic antioxidants can provide low-color primary stabilization, while phosphites can decompose hydroperoxides generated during melt processing. This is why formulators often evaluate packages containing both radical scavengers and processing stabilizers rather than relying on a single antioxidant.
The concept of Primary and secondary antioxidants is especially useful here. Primary antioxidants interrupt radical chain reactions, while secondary antioxidants typically react with hydroperoxides before those species decompose into additional radicals. Well-designed Combined antioxidants can therefore protect the polymer at different stages of processing and service.
How Antioxidant 405 Protects Polymers
During oxidation, polymer radicals can react with oxygen to form peroxy radicals. These species abstract hydrogen from nearby polymer chains, generating hydroperoxides and new radicals. The process can repeat and accelerate. Aromatic amine antioxidants are effective because they can donate hydrogen to reactive radical species and form resonance-stabilized antioxidant-derived radicals that are less likely to continue the destructive chain reaction.
In an industrial process, this mechanism matters because the polymer is often exposed to several stressors simultaneously. An extruder can introduce heat and shear; curing can expose an elastomer to prolonged elevated temperature; and final components may operate in hot air, oil, or mechanically demanding environments. Antioxidant 405 is selected when the formulation needs robust protection against this type of thermal-oxidative stress.
Applications
Rubber and elastomer compounds
Rubber is one of the most established application areas for Antioxidant 405. Supplier literature highlights neoprene (CR), nitrile rubber (NBR), EPDM, HNBR, acrylic rubber, natural rubber, SBR, and polyisoprene among the systems in which aromatic amine stabilization can be useful. In these materials, oxidation can reduce elongation, increase hardness, promote cracking, and weaken long-term mechanical performance.
HNBR and other heat-resistant elastomers are especially relevant because their end-use environments can involve elevated temperatures for extended periods. Antioxidant 405 may be considered in seals, hoses, belts, gaskets, cable compounds, and molded rubber parts where thermal aging is a key failure mechanism. The actual additive package should still be validated against cure chemistry, compression set, fluid resistance, color, and aging requirements.
Polyolefins and styrenic polymers
Antioxidant 405 can also be used in polyolefin and styrenic systems when strong thermal stabilization is required. Polyethylene and polypropylene can undergo molecular-weight changes and property loss during processing if oxidation is not controlled. However, color requirements are important: amine antioxidants can produce more color than high-quality hindered phenolics, so Antioxidant 405 is not automatically the first choice for every white, transparent, or highly color-sensitive plastic application.
For such polymers, formulators often compare Antioxidant 405 with phenolic antioxidants such as Antioxidant 1010, Antioxidant 1076, or Antioxidant 3114, and with phosphite processing stabilizers such as Antioxidant 168. The best package depends on processing severity, long-term heat exposure, target color, migration limits, and the required cost-performance balance.
Polyurethane, polyols, and foam systems
Oxidative stability can be important in polyols and polyurethane-related applications because raw materials and finished foams may be exposed to heat during processing, storage, or service. Technical literature lists Antioxidant 405 for polyols and polyurethane foams, where it can contribute to heat-aging resistance. Formulators should confirm compatibility with catalysts, isocyanates, pigments, flame retardants, and other additives used in the specific polyurethane system.
Hot-melt adhesives and specialty polymer formulations
Hot-melt adhesives are repeatedly heated during manufacture and application. Oxidation can cause viscosity drift, gel formation, odor, color change, and performance loss. Antioxidant 405 may be used as part of a stabilization package in hot-melt systems where elevated processing temperatures demand strong antioxidant performance. Resin chemistry, tackifier type, wax content, color target, and end-use temperature all influence the final antioxidant selection.
Lubricants and other industrial systems
Some supplier data also identifies lubricant applications. In lubricating systems, oxidation can increase acidity, viscosity, deposits, and sludge formation. Aromatic amine antioxidants are a well-established class for high-temperature oxidation control in many lubricant technologies. When Antioxidant 405 is considered for such use, formulators should evaluate solubility, base-oil compatibility, additive interactions, volatility, and the regulatory requirements of the specific lubricant market.
| Application area | Why Antioxidant 405 may be considered | Key formulation check |
| NBR, HNBR, CR, EPDM and acrylic rubber | Heat-aging and oxidation resistance | Cure system, color, compression set, fluid aging |
| Polyolefins | Protection during processing and thermal exposure | Color, migration, synergy with phosphites |
| Polyamides and styrenics | High-temperature stabilization | Processing temperature and color stability |
| Polyols / polyurethane | Thermal and oxidative aging protection | Catalyst and formulation compatibility |
| Hot-melt adhesives | Control of oxidation during repeated heating | Viscosity, odor, color and gel formation |
| Lubricants | Oxidation control at elevated temperature | Solubility and additive-package interactions |
Advantages
High-temperature performance
The central advantage of Antioxidant 405 is performance under thermal stress. When a polymer must retain mechanical or functional properties after prolonged heat exposure, a high-activity aromatic amine antioxidant can offer stronger protection than a low-intensity stabilizer used only for basic processing protection.
Relatively low volatility
Lower volatility helps retain active antioxidant during high-temperature processing and aging. This can be particularly important in elastomers, hot-melt systems, and engineering formulations that remain hot for long periods or undergo multiple processing steps.
Multipurpose use
The same chemistry is reported across several polymer families, which gives formulators a useful technical option when they need to standardize or simplify antioxidant screening. Nevertheless, a broad application range should not be confused with universal suitability. Each final formulation needs its own validation.
Synergistic stabilization potential
Antioxidant packages often perform better when different mechanisms are combined. A primary antioxidant can reduce radical propagation while a phosphite or sulfur-containing stabilizer may address hydroperoxides. This multi-mechanism approach can improve both processing stability and long-term aging performance when the components are properly selected.
Antioxidant 405 Compared with Other Stabilizer Types
| Stabilizer | Best suited to | Key consideration |
| Antioxidant 405 | Strong thermal-oxidative aging protection, especially in elastomers | May cause some discoloration; color-sensitive uses need testing |
| Antioxidant 1010 | Long-term primary stabilization with good color properties | Often paired with a phosphite for processing protection |
| Antioxidant 1076 | Broad long-term phenolic stabilization | Selection depends on migration and processing requirements |
| Antioxidant 3114 | High-molecular-weight long-term stabilization | Compatibility and final application requirements must be checked |
| Antioxidant 168 | Processing stabilization and hydroperoxide decomposition | Usually paired with a primary antioxidant for a broader protection package |
This comparison explains why Antioxidant 405 should not be judged only by asking whether it is ‘better’ than a phenolic or phosphite. The stabilizers address different formulation priorities. In a dark or technically colored elastomer requiring severe heat-aging resistance, an aromatic amine may be highly attractive. In a transparent or very light-colored plastic, a phenolic/phosphite package may be preferred. The right decision comes from matching the antioxidant chemistry to the failure mode and the appearance requirements of the product.
Selection and Formulation Considerations
1. Define the actual degradation problem
Before choosing an antioxidant, determine whether the main challenge is processing degradation, long-term heat aging, oxidation in service, UV exposure, metal-catalyzed degradation, color change, or a combination of these factors. Antioxidant 405 is primarily relevant to thermal-oxidative stabilization; it should not be expected to replace UV absorbers, HALS, metal deactivators, or other specialized stabilizers when those mechanisms dominate.
2. Check color and staining requirements
Aromatic amine antioxidants are not the preferred choice when extremely low color or non-staining performance is essential. Akrochem notes that Antioxidant 405 can discolor slightly and is generally better suited to colors other than very light whites or yellows. This trade-off is important: high heat-aging performance can be valuable, but it must be balanced against appearance targets.
3. Optimize the dosage by testing
There is no single universal dosage that is correct for every polymer. Supplier recommendations can provide a starting point, but the final loading should be established through laboratory trials and aging tests under realistic processing and end-use conditions. For rubber, Akrochem reports typical use at approximately 1 to 4 phr, but this should be treated as supplier guidance rather than a universal specification.
4. Evaluate synergy instead of only single-additive performance
A formulation may benefit from combining Antioxidant 405 with another antioxidant type. Supplier literature reports synergy with selected antioxidants, and broader polymer practice commonly combines primary chain-breaking antioxidants with hydroperoxide decomposers. When building a package, evaluate melt stability, long-term oven aging, color, tensile retention, viscosity or MFI retention, odor, blooming, and extraction resistance as relevant to the product.
5. Confirm regulatory and application-specific suitability
Regulatory status must be checked for the exact commercial grade, intended use, and country of sale. PubChem and ECHA confirm the chemical identity of CAS 10081-67-1, and ECHA lists the substance as REACH registered. Regulatory acceptance in a general chemical inventory does not automatically mean approval for every food-contact, medical, potable-water, or consumer application. The supplier’s current SDS, TDS, declarations, and applicable regional regulations should be reviewed before commercialization.
Common Mistakes to Avoid
- Selecting Antioxidant 405 only because it has strong heat-aging performance, without checking the final product’s color or staining limits.
- Using a supplier’s suggested dosage as a fixed universal value instead of validating the loading in the actual polymer and process.
- Expecting one antioxidant to solve UV degradation, metal-catalyzed oxidation, processing instability, and long-term aging simultaneously.
- Ignoring interactions with curing agents, phosphites, sulfur-containing stabilizers, pigments, fillers, flame retardants, or other additives.
- Comparing antioxidants only by price per kilogram rather than by required dosage, retained properties, service life, processing scrap, and total formulation cost.
- Purchasing by trade name alone without confirming CAS No. 10081-67-1, chemical identity, purity, physical form, and supplier specifications.
Frequently Asked Questions
What is Antioxidant 405?
Antioxidant 405 is an aromatic amine antioxidant commonly identified as 4,4′-bis(alpha,alpha-dimethylbenzyl)diphenylamine, CAS No. 10081-67-1. It is used to improve resistance to heat and oxidative aging in polymers, elastomers, and selected industrial formulations.
What polymers can use Antioxidant 405?
Supplier technical literature reports use in neoprene, nitrile rubber, EPDM, HNBR, acrylic rubber, polyolefins, styrenics, polyamides, polyols, polyurethane foams, hot-melt adhesives, and some lubricant systems. Suitability must be tested in the actual formulation.
Is Antioxidant 405 suitable for high-temperature applications?
It is commonly selected for demanding thermal-aging conditions because aromatic amine antioxidants offer strong heat and oxidation resistance and this product is valued for relatively low volatility. Final performance should be confirmed with heat-aging tests that reproduce real service conditions.
Does Antioxidant 405 cause discoloration?
It can cause some discoloration because it is an amine antioxidant. Supplier literature describes the discoloration as relatively slight, but very light white or yellow applications may require a lower-color antioxidant system.
Can Antioxidant 405 be combined with other antioxidants?
Yes. It can be evaluated with complementary antioxidant classes when the formulation needs multiple stabilization mechanisms. For example, a phosphite such as Antioxidant 168 may be used for processing stabilization, while phenolic antioxidants such as Antioxidant 1010 can be evaluated where low color and long-term stabilization are important.
What is the recommended dosage of Antioxidant 405?
There is no universal dosage. In rubber applications, one supplier reports typical use at about 1–4 phr, but the correct amount depends on polymer type, processing severity, end-use temperature, other stabilizers, and performance targets. Laboratory validation is essential.
Is Antioxidant 405 the same as Antioxidant 445?
The names are used by some suppliers for the same chemical identity, CAS No. 10081-67-1. Because trade names vary, purchasers should always confirm the chemical name and CAS number on the technical documentation.
How should Antioxidant 405 be selected for an industrial formulation?
Start with the degradation mechanism, required service temperature, color limits, polymer chemistry, processing conditions, regulatory requirements, and interaction with the rest of the additive package. Then confirm the choice through controlled processing and aging tests.
Conclusion
Antioxidant 405 is a versatile aromatic amine stabilizer for industrial formulations that need strong thermal-oxidative protection. Its low volatility, broad polymer applicability, and strong heat-aging performance make it especially relevant to rubber and elastomer compounds, while technical literature also supports use in polyolefins, styrenics, polyamides, polyols, polyurethane systems, hot-melt adhesives, and lubricants.
Its strongest advantage is not that it replaces every other antioxidant, but that it provides a specific performance profile: robust radical-scavenging activity under demanding thermal conditions. Formulators should balance this benefit against color requirements and should compare it with phenolic and phosphite systems where necessary. The most reliable approach is to define the actual degradation problem, select complementary stabilizers when appropriate, and validate the formulation through processing trials and realistic aging tests before commercial use.
