What is the recommended dosage of Irgafos 168 in plastics?

The use of antioxidants in plastics is crucial for maintaining their quality, durability, and performance over time. Irgafos 168 is one of the most widely used secondary antioxidants in the plastics industry. As a reputable supplier of Irgafos 168, we often receive inquiries about the recommended dosage of this antioxidant in plastics. In this blog post, we will provide a comprehensive overview of the factors influencing the dosage of Irgafos 168 and offer some general guidelines to help you achieve the best results.

Understanding Irgafos 168

Irgafos 168, also known as tris(2,4 - di - tert - butylphenyl) phosphite, is a phosphite - based secondary antioxidant. It works in synergy with primary antioxidants such as Irganox 3114, AT - 10 [(/petrochemical/antioxidant/at-10.html)] and AT - 168 [(/petrochemical/antioxidant/at-168.html)] to provide excellent protection against thermo - oxidative degradation of plastics. Secondary antioxidants like Irgafos 168 decompose hydroperoxides formed during the oxidation process, preventing them from further reacting and causing chain - scission or cross - linking in the polymer matrix.

Factors Influencing the Dosage of Irgafos 168

1. Type of Plastic Resin

Different plastic resins have varying degrees of susceptibility to oxidation. For instance, polyolefins such as polyethylene (PE) and polypropylene (PP) are prone to thermo - oxidative degradation due to the presence of tertiary carbon atoms in their molecular structure. These polymers require a relatively higher dosage of Irgafos 168 to achieve adequate protection. On the other hand, plastics like polystyrene and polycarbonate are more resistant to oxidation and may need a lower dosage.

2. Processing Conditions

The processing conditions of plastics, including temperature, shear stress, and residence time, greatly affect the oxidation rate. Higher processing temperatures and longer residence times increase the likelihood of oxidation. In such cases, a higher dosage of Irgafos 168 is required to counteract the increased oxidative stress. For example, in extrusion processes where plastics are subjected to high temperatures for an extended period, a higher concentration of the antioxidant may be necessary.

3. End - Use Application

The intended end - use application of the plastic product also plays a significant role in determining the dosage of Irgafos 168. Plastics used in outdoor applications, such as automotive parts, construction materials, and agricultural films, are exposed to environmental factors like sunlight, oxygen, and heat. These external factors accelerate the oxidation process, so a higher dosage of Irgafos 168 is needed to ensure long - term stability. In contrast, plastics used in indoor applications with less exposure to harsh environmental conditions may require a lower dosage.

4. Presence of Other Additives

Some additives in plastics can either enhance or inhibit the effectiveness of Irgafos 168. For example, certain pigments, fillers, and stabilizers may have an impact on the antioxidant's performance. In some cases, they may synergistically work with Irgafos 168, allowing for a lower dosage. However, in other cases, they may interfere with the antioxidant's action, necessitating a higher dosage.

General Dosage Guidelines

While the optimal dosage of Irgafos 168 depends on the specific factors mentioned above, the following general guidelines can serve as a starting point for different types of plastics:

Polyolefins (PE and PP)

• For general - purpose PE and PP applications with mild processing conditions and indoor use, a dosage of 0.1% - 0.3% (by weight) of Irgafos 168 combined with an appropriate primary antioxidant is usually sufficient.
• In cases where the polyolefins are processed at high temperatures or are intended for outdoor use, the dosage of Irgafos 168 can be increased to 0.3% - 0.5%. For more demanding applications, such as automotive under - the - hood parts, the dosage may even reach up to 0.7%.

Polystyrene

Since polystyrene is relatively more resistant to oxidation, a dosage of 0.05% - 0.15% of Irgafos 168 is typically recommended. This is usually sufficient to provide good protection during processing and in normal indoor use.

Polycarbonate

Polycarbonate also has a certain degree of resistance to oxidation. However, due to its high - temperature processing requirements, a dosage of 0.1% - 0.2% of Irgafos 168 is generally used in combination with a primary antioxidant to prevent yellowing and maintain the mechanical properties of the material.

Engineering Plastics

Engineering plastics such as polyamides, polyesters, and polyacetals often require a more precise dosage of Irgafos 168. Depending on the specific polymer and its application, the dosage can range from 0.1% - 0.4%. These plastics are often used in high - performance applications, so the antioxidant dosage needs to be carefully optimized to meet the strict quality requirements.

Importance of Proper Dosage

Determining the correct dosage of Irgafos 168 is of utmost importance. If the dosage is too low, the plastic will not receive sufficient protection against oxidation, leading to premature degradation, discoloration, loss of mechanical properties, and reduced service life. On the other hand, an excessive dosage of Irgafos 168 can have several negative effects. It may increase the cost of production without providing additional benefits. In some cases, it can also cause problems such as migration, blooming, and reduced heat stability of the plastic.

Conducting Trials for Optimal Dosage

Given the complexity of the factors influencing the dosage of Irgafos 168, it is highly recommended to conduct small - scale trials before full - scale production. These trials should simulate the actual processing conditions and end - use environment of the plastic product. By testing different dosages of Irgafos 168 and monitoring the performance of the plastic over time, you can determine the optimal dosage for your specific application.

Conclusion

As a reliable supplier of Irgafos 168, we understand the importance of providing accurate information on dosage recommendations. The appropriate dosage of Irgafos 168 in plastics depends on multiple factors, including the type of plastic resin, processing conditions, end - use application, and the presence of other additives. By considering these factors and following the general guidelines provided, you can achieve the best balance between cost - effectiveness and protection against oxidation.

If you are looking for high - quality Irgafos 168 for your plastic applications, we are here to assist you. Our team of experts can provide further guidance on dosage optimization and help you choose the most suitable antioxidant solutions. Contact us to start a discussion about your specific needs and explore how our Irgafos 168 can enhance the performance and durability of your plastic products.

References

• "Plastic Additives Handbook," 6th Edition, Hanser Publications.
• "Antioxidants in Plastics: Fundamentals and Applications," Wiley - VCH.
• Technical literature from major plastic resin manufacturers on the use of antioxidants in their products.