Demand Driven by High-End Manufacturing: A Guide to Antioxidant KY-405 — the Heat- and Oxidation-Resistant "Guardian" of Polymer Materials
Since the start of 2026, the rapid growth of downstream industries such as new-energy vehicles, rail transit, and high-end wire and cable has placed ever-higher demands on the heat resistance and aging resistance of polymer materials like rubber and plastics. As a result, demand keeps rising for high-performance antioxidants — the key to "anti-aging" in these materials. At the same time, guided by policies such as the Implementation Plan for the Innovative Development of the Fine Chemical Industry (2024–2027), domestically produced high-end rubber and plastic additives are increasingly replacing imports. In this industry explainer, we take a closer look at a representative high-end amine antioxidant — KY-405 — to understand "what it is, where it is used, and how to use it."
1. Meet KY-405: an amine antioxidant with its molecular weight "written" into its name
The chemical name of KY-405 is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (CAS No. 10081-67-1). Its molecular formula is C₃₀H₃₁N and its molecular weight is approximately 405.58 — neatly echoing the "405" in the product designation. It belongs to the same class as Naugard 445 from Uniroyal (USA) and Nocrac CD from Ouchi (Japan). A general-purpose aromatic amine antiaging agent (antioxidant) for rubber and plastics, it is also one of the representative domestic products replacing imported high-end additives.
In terms of physical and chemical properties, KY-405 is a white to off-white powder or fine granule, with a melting point of about 101 °C and a thermal decomposition temperature as high as 280 °C. It dissolves readily in organic solvents such as acetone, chloroform, benzene, and cyclohexane, as well as in rubber, and is slightly soluble in water and ethanol. It stands out for its high molecular weight, low volatility, and resistance to oil and high temperatures, and it is also one of the few amine antioxidants that is non-toxic, odorless, and light in color (oral LD₅₀ in rats greater than 5000 mg/kg, with no significant irritation on skin or eye contact).
◆ A quick note: what "aging" do antioxidants actually prevent?
During processing and long-term use, polymer materials such as rubber and plastics undergo "aging" under the combined action of heat, oxygen, and light — manifesting as hardening, embrittlement, cracking, tackiness, discoloration, and loss of elasticity. Fundamentally, this is a free-radical chain oxidation reaction of the molecular chains in the presence of oxygen. Antioxidants work by scavenging free radicals and interrupting the oxidative chain reaction, thereby slowing this process. Amine antioxidants like KY-405 are especially effective at resisting thermo-oxidative aging in high-temperature environments, which is why they are often used as "primary antioxidants."
2. Where it is used: the unsung hero from tires to cables
Thanks to its excellent heat resistance and antioxidant performance, KY-405 is used across many fields, including rubber, plastics, polyurethane, wire and cable, and lubricating oils:
Rubber products: Used to protect natural rubber and synthetic rubbers such as styrene-butadiene (SBR), isoprene (IR), chloroprene (CR), and butyl (IIR) rubbers against aging. It is particularly effective against heat- and light-induced aging in chloroprene rubber, acrylate rubber (ACM), nitrile rubber (NBR), and ethylene-propylene-diene rubber (EPDM).
Plastic masterbatch: Used for the oxidation resistance of plastics such as polyethylene, polypropylene, and polyvinyl chloride (PVC).
Polyurethane and polyether polyols: Can serve as an antioxidant for polyurethane foam. In the production of polyether polyols, it markedly raises the system's oxidation induction temperature and is highly effective in preventing high-temperature "core scorching" and reducing yellowing of the finished products.
Wire and cable: Used in rubber wires and cables, especially in colored chloroprene cable sheathing, where it provides notable protection against heat, light, and ozone aging.
Other fields: Can also be used as an antioxidant for food-packaging materials and adhesives (such as hot-melt adhesives), and as a lubricating-oil antioxidant.
3. Application Q&A: the practical know-how
Here are a few points addressing common questions from rubber and plastic processors:
Q1: What is the recommended dosage?A: Typically added at 1–3 phr (parts per hundred rubber) in the rubber or plastic matrix; the exact amount can be adjusted according to the product formulation, processing temperature, and service environment.
Q2: Will it affect rubber vulcanization?A: KY-405 disperses easily in rubber and has no significant effect on vulcanization performance.
Q3: Can it be used in combination with other antioxidants?A: Yes. KY-405 shows good synergy with hindered phenols, phosphites, and sulfur-containing antioxidants. It often serves as a key component in thermo-oxidative antioxidant blend systems, delivering a "1 + 1 > 2" protective effect, and is a preferred choice for thermo-oxidative formulations.
Q4: Why is it suitable for high-temperature processing?A: Owing to its high molecular weight, low volatility, and thermal decomposition temperature of up to 280 °C, KY-405 is not easily lost through volatilization during high-temperature processing, and its antioxidant durability is clearly superior to that of some phenolic antioxidants such as Antioxidant 1010 and BHT (264). It can serve as an ideal substitute for, or an effective complement to, such products.
Q5: Will the products discolor or experience migration?A: As an aromatic amine antioxidant, KY-405 may undergo slight discoloration under sunlight exposure or prolonged exposure to air, but it does not migrate. For light-colored, natural-white, or color-sensitive products, it is advisable to carry out a small-scale evaluation in advance, or to use it in combination with other types of antioxidants.
Q6: How should it be stored?A: Store in a cool, dry, well-ventilated warehouse, protected from light and sealed; keep it away from moisture, sunlight, and rain, and away from fire and heat sources. The product is conventionally packaged in kraft paper bags lined with black plastic film (net weight 25 kg), and can also be customized to customer requirements.
Conclusion
A small bag of antioxidant embodies a great deal of know-how for extending the service life of polymer materials. As downstream high-end manufacturing continues to raise its requirements for material performance and as domestic high-end additives accelerate their replacement of imports, amine antioxidants like KY-405 — combining high performance, good color, and safety — are seeing their market steadily open up. Rooted in the national-level circular-economy chemical park in Yaojiagang, Zhijiang, Yichang, chemical and advanced-materials companies will continue to win the market through technology and quality throughout this process.
