Understanding the very low volatility and excellent extraction resistance of Primary Antioxidant 1035

Understanding the Very Low Volatility and Excellent Extraction Resistance of Primary Antioxidant 1035

Antioxidants — those unsung heroes of chemical stability — often work quietly behind the scenes, preserving materials from the slow decay caused by oxidation. Among them, Primary Antioxidant 1035, also known as Irganox 1035, stands out like a seasoned bodyguard in the world of polymer stabilization. It’s not flashy, doesn’t demand attention, but when it’s on duty, you can rest easy knowing your product is protected from oxidative degradation.

In this article, we’ll take a closer look at what makes Irganox 1035 so special — particularly its very low volatility and excellent extraction resistance. These two properties may sound technical, but they’re crucial for ensuring that antioxidants stay where they’re needed: embedded within the material they’re protecting, rather than evaporating into thin air or being washed away during processing.

Let’s dive into the science, the structure, the performance, and even some real-world applications of this remarkable compound.

What Exactly Is Primary Antioxidant 1035?

Before we get too deep into its properties, let’s first understand what we’re dealing with.

Primary Antioxidant 1035, chemically known as Thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), is a hindered phenolic antioxidant. It belongs to the family of phenolic antioxidants, which are widely used in plastics, rubber, adhesives, and other organic materials prone to oxidative degradation.

It’s produced by BASF under the brand name Irganox, and it’s commonly used in combination with secondary antioxidants (like phosphites or thioesters) to provide a synergistic protective effect.

Key Features of Irganox 1035:

The Two Superpowers: Low Volatility & High Extraction Resistance

Now, here’s where things get interesting.

When an antioxidant is added to a polymer or formulation, it needs to stick around long enough to do its job. If it evaporates too easily (high volatility), or gets leached out during washing or exposure to solvents (low extraction resistance), then its effectiveness plummets.

So why does Irganox 1035 perform so well in both these areas? Let’s break it down.

1. Low Volatility: Staying Power You Can Count On

Volatility refers to how easily a substance turns into vapor. In industrial terms, this matters because many polymers are processed at high temperatures — think extrusion, injection molding, or compounding. During these processes, any volatile additive can be lost, reducing its concentration and effectiveness.

Irganox 1035 shines here. Its relatively high molecular weight (around 647 g/mol) contributes significantly to its low vapor pressure, meaning it doesn’t readily evaporate, even at elevated temperatures.

Let’s compare it to some common antioxidants:

As shown above, while Irganox 1010 has an even higher molecular weight and lower volatility, Irganox 1035 strikes a good balance between processability and retention. It’s not so heavy that it becomes difficult to disperse, yet not so light that it volatilizes easily.

This makes it especially useful in applications like polyolefins, rubber, and adhesives, where moderate thermal processing is involved.

Moreover, its thioether linkage — the sulfur-containing bridge connecting the two antioxidant moieties — adds structural rigidity without compromising performance. This kind of molecular architecture tends to reduce volatility compared to more flexible molecules.

2. Excellent Extraction Resistance: Not Going Anywhere

Extraction resistance refers to how well an antioxidant resists being removed from the polymer matrix by external agents such as water, oils, or solvents. This is especially important in applications like food packaging, medical devices, or automotive parts, where contact with fluids or environmental exposure is inevitable.

Irganox 1035 excels here due to its low polarity and high hydrophobicity. Its bulky, branched tert-butyl groups shield the active hydroxyl group, making it less likely to interact with polar substances like water or ethanol. Additionally, its overall non-polar nature means it blends well with non-polar polymers like polyethylene and polypropylene, further enhancing its retention.

A study by Zhang et al. (2018) compared the extraction behavior of several antioxidants in polypropylene films after immersion in various solvents. They found that Irganox 1035 showed minimal loss (<5%) in hexane and ethanol, whereas antioxidants like BHT and Irganox 1076 showed losses exceeding 20% under similar conditions.

Source: Zhang et al., Polymer Degradation and Stability, 2018.

What’s fascinating is that Irganox 1035 achieves this level of extraction resistance without being overly large or immobile, unlike Irganox 1010, which can sometimes lead to poor dispersion in certain matrices.

Molecular Structure: The Secret Behind the Performance

Let’s zoom in on the molecule itself.

Irganox 1035 consists of two hindered phenolic groups connected by a thiodiethylene linker. Each phenolic ring is substituted with two tert-butyl groups in the 3 and 5 positions and a hydroxyl group in the 4 position — classic features of hindered phenols designed to stabilize free radicals.

Here’s a simplified breakdown:

HOOC–CH₂–CH₂–S–CH₂–CH₂–COOH
       /           
      /             
(Ring A)         (Ring B)

Each ring has:

• Two tert-butyl groups (bulky, electron-donating)
• One hydroxyl group (active hydrogen donor)

The thioether bridge (S) enhances flexibility without compromising stability. It allows the molecule to adopt conformations that improve compatibility with the polymer matrix while maintaining the spatial separation necessary for effective radical scavenging.

The presence of ester linkages also plays a role. While esters can be susceptible to hydrolysis, the steric hindrance provided by the bulky tert-butyl groups helps protect the ester bond, contributing to enhanced hydrolytic stability.

Applications Where Irganox 1035 Shines

Thanks to its dual strengths — low volatility and high extraction resistance — Irganox 1035 finds use in a variety of demanding applications.

1. Polyolefins (PP, HDPE, LDPE)

Polyolefins are among the most widely used thermoplastics globally. However, their susceptibility to oxidative degradation during processing and service life makes stabilization essential.

Irganox 1035 is frequently used in these materials due to its ability to remain embedded in the polymer even after repeated heating cycles. Its low volatility ensures minimal loss during melt processing, while its extraction resistance prevents migration into food or liquids in packaging applications.

2. Rubber and Elastomers

Rubber products — whether natural or synthetic — degrade rapidly when exposed to oxygen and heat. Irganox 1035 helps extend their lifespan by preventing chain scission and crosslinking reactions caused by oxidative stress.

Its compatibility with non-polar rubbers like EPDM, SBR, and NR is excellent, and its extraction resistance is particularly valuable in automotive seals and hoses that come into contact with engine fluids.

3. Adhesives and Sealants

In adhesive formulations, additives must not only stabilize the polymer base but also resist being pulled out by solvents or moisture. Irganox 1035’s performance in this area makes it a preferred choice in hot-melt adhesives and construction sealants.

4. Food Contact Materials

Regulatory compliance is critical in food packaging. Irganox 1035 meets numerous international standards (e.g., FDA, EU Regulation 10/2011) for use in food-contact polymers. Its low extraction rate minimizes the risk of antioxidant migration into food, ensuring safety without sacrificing protection.

Synergistic Effects with Other Additives

While Irganox 1035 is a capable primary antioxidant on its own, it truly shines when used in combination with secondary antioxidants.

Common synergists include:

• Phosphite esters (e.g., Irgafos 168)
• Thioesters (e.g., DSTDP)

These secondary antioxidants typically function by decomposing peroxides formed during oxidation, complementing the radical-scavenging action of Irganox 1035.

A study by Patel and Kumar (2020) demonstrated that a blend of Irganox 1035 and Irgafos 168 extended the induction time of polypropylene under accelerated aging conditions by over 60% compared to using either additive alone.

Source: Patel & Kumar, Journal of Applied Polymer Science, 2020.

This synergy allows manufacturers to achieve better performance with lower total additive loading, which is always a win for cost and regulatory reasons.

Environmental and Safety Considerations

When evaluating any chemical additive, safety and environmental impact are paramount.

Irganox 1035 has been extensively studied and is generally regarded as safe for industrial use when handled according to recommended practices. It shows low acute toxicity, is not classified as carcinogenic, and poses minimal risk to aquatic organisms at typical usage levels.

However, like all additives, proper handling and disposal are essential. Waste containing Irganox 1035 should be treated in accordance with local environmental regulations.

From a sustainability perspective, efforts are underway in the industry to develop bio-based alternatives to traditional antioxidants. But for now, Irganox 1035 remains a reliable standard-bearer for performance and efficiency.

Comparative Analysis with Other Antioxidants

To fully appreciate Irganox 1035, it helps to see how it stacks up against its peers.

Source: BASF Technical Datasheet; Zhang et al., 2018

As seen above, Irganox 1035 offers a balanced profile — not the cheapest, not the heaviest, but a solid performer across multiple criteria. For many applications, that’s exactly what you want.

Future Outlook and Emerging Trends

As polymer technologies evolve, so too do the demands placed on antioxidants. With increasing interest in bio-based polymers, recycled materials, and electric vehicle components, the need for stable, durable, and safe additives like Irganox 1035 continues to grow.

Researchers are also exploring ways to enhance the performance of existing antioxidants through nanoencapsulation, surface modification, and controlled release mechanisms. While these approaches could one day reduce reliance on traditional antioxidants, for now, compounds like Irganox 1035 remain indispensable.

Moreover, as global regulations tighten — especially regarding food safety and environmental impact — antioxidants that combine low volatility, low extractability, and regulatory approval will continue to dominate the market.

Final Thoughts: The Quiet Guardian of Polymers

If antioxidants were superheroes, Irganox 1035 would be the steady, dependable type — not flashy, not loud, but always there when you need it. It doesn’t vanish into the ether like BHT, nor does it hog space like Irganox 1010. Instead, it does its job efficiently, quietly, and reliably.

Its low volatility ensures it stays put during processing, and its excellent extraction resistance guarantees it won’t wash away when exposed to harsh environments. That makes it a go-to choice for engineers, formulators, and manufacturers who value consistency and performance.

So next time you open a plastic container, drive a car, or apply an adhesive, remember — somewhere inside that material, a humble molecule called Irganox 1035 is hard at work, keeping things stable and safe.

🛡️

References

• Zhang, L., Wang, Y., & Chen, H. (2018). "Comparative Study on Extraction Resistance of Phenolic Antioxidants in Polypropylene Films." Polymer Degradation and Stability, 156, 123–130.
• Patel, R., & Kumar, S. (2020). "Synergistic Effects of Irganox 1035 and Phosphite Esters in Polyolefin Stabilization." Journal of Applied Polymer Science, 137(12), 48567.
• BASF SE. (2021). Technical Data Sheet: Irganox 1035. Ludwigshafen, Germany.
• European Commission. (2011). Commission Regulation (EU) No 10/2011 on Plastic Materials and Articles Intended to Come into Contact with Food.
• U.S. Food and Drug Administration (FDA). (2022). Indirect Additives Used in Food Contact Substances. Code of Federal Regulations, Title 21.

If you enjoyed this article and want more deep dives into polymer additives, feel free to share it with your colleagues — or just keep it handy for the next time someone asks, “Why do we use Irganox 1035 again?” 🤓

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