The plastics and rubber industries rely heavily on chemical additives to enhance the properties and extend the lifespan of their products. Among these essential additives are antioxidants, which play a critical role in preventing degradation caused by oxidation. While various types of antioxidants exist, phosphite antioxidants, such as the widely used Antioxidant 168 (CAS 31570-04-4), offer unique benefits, particularly in processing stability and synergy with other stabilizers.

Understanding Oxidation in Polymers
Polymers are susceptible to oxidation throughout their lifecycle – from manufacturing and processing to end-use. This process, driven by heat, light, and oxygen, leads to the formation of free radicals and hydroperoxides within the polymer matrix. These reactive species initiate chain reactions that result in detrimental changes like chain scission (reducing molecular weight and strength), cross-linking (making the material brittle), discoloration, and a general loss of desirable physical and mechanical properties. Effectively managing oxidation is key to producing durable and high-performing plastic goods.

The Mechanism of Phosphite Antioxidants
Phosphite antioxidants, like Antioxidant 168, function as secondary antioxidants. Their primary role is to decompose hydroperoxides into stable, non-radical products. This action interrupts the auto-oxidation cycle before it can cause significant damage to the polymer chains. Specifically, the P-O bond in the phosphite ester is highly reactive towards hydroperoxides. During this reaction, the phosphite is oxidized to a phosphate, a stable byproduct, effectively neutralizing the harmful hydroperoxide.

Key Advantages of Antioxidant 168
Antioxidant 168 is celebrated for several distinct advantages:

  • Processing Protection: Phosphites are particularly effective during the high-temperature processing of polymers. They protect the polymer melt from thermal-oxidative degradation, ensuring that properties are maintained from extrusion to molding.
  • Synergy with Primary Antioxidants: Antioxidant 168 is rarely used in isolation. Its true strength lies in its synergistic combination with primary antioxidants, typically hindered phenols. While hindered phenols act as radical scavengers, phosphites like Antioxidant 168 handle the hydroperoxide decomposition. This combined action provides superior protection compared to either type used alone, leading to enhanced long-term thermal stability.
  • Hydrolytic Stability: A critical feature of Antioxidant 168 is its superior resistance to hydrolysis, meaning it maintains its effectiveness even when exposed to moisture during storage or processing. This is a significant advantage over less stable phosphites.
  • Low Volatility: This property ensures that the additive remains within the polymer during processing, preventing loss and maintaining its protective function.

Applications and Sourcing
Antioxidant 168 finds broad application in polyolefins (like PP and PE), polycarbonates, polyamides, ABS, PVC, rubber, adhesives, and coatings. Its ability to protect polymers during processing makes it invaluable for manufacturers in the automotive, packaging, construction, and electronics sectors.

When sourcing this critical additive, partnering with reliable manufacturers and suppliers is essential. Companies that specialize in producing high-purity Antioxidant 168, like NINGBO INNO PHARMCHEM CO.,LTD., ensure consistency, performance, and competitive pricing. Investing in quality raw materials is fundamental to achieving superior end-product performance and customer satisfaction. We encourage you to reach out to us to learn more about our comprehensive range of polymer additives and how we can support your specific manufacturing needs.