Bisphenol-A 

You have probably heard about the BPA. A chemical compound produced in hundreds of millions of tones per year remains an extremely useful feedstock for manufacturing a variety of plastics for any application you might think of: from furniture parts to pipeline coatings. General public has become aware of the BPA because of the studies that revealed potential endocrine disruption effects from Bisphenol-A containing plastics. 

BPA in epoxy resins

Chemistry can be hard to comprehend at times, but it can be surprisingly straightforward, even not for chem-savvy folks. Think about hexagons, and how beehives are built from hexagonal-shaped honeycombs. Hexagons provide a strong foundation capable of withstanding load effectively. The same applies to polymer chemistry: BPA is so popular in epoxy manufacturing and plastics in general because of the two hexagon-shaped rings that offer hardness, rigidity and durability to the final material. 

BPA-free epoxy resins

Some resins claim to be BPA-free; you might think, how is it BPA-free if BPA is used for producing them? The answer is complex but could be simplified to an example below:

Aspirin is a common medication that is used to treat symptoms like headache, fever, muscle aches and others. It is produced in a multi-step synthesis pathway and includes use of a compound such as phenol - a harmful and hazardous chemical. But we know that aspirin is pretty safe and is phenol-free. This is because of the strict technological processes pharmaceutical companies use to ensure that all the free phenol becomes a part of a larger molecule - acetylsalicylic acid (aspirin), and there is no leftover phenol remains found in the pill of aspirin.

The same applies to epoxy resin manufacturing. BPA is a building block for a larger molecule of epoxy, however epoxy resin can be produced essentially BPA-free if highest quality grade raw materials are used and strict technological processes are followed by a manufacturer.

Proper technological processes and high quality raw materials make it possible to make the product BPA or phenol free even though these chemicals participate in the various production stages

Is it possible to make the resin not from the BPA?

Yes! But...

Epoxy resins made from different sources than the BPA might experience accelerated yellowing, decrease in structural integrity and they usually cost 30-100% more expensive to produce. Recent progress in industrial chemistry allow avoiding these negatives effects with novel bio-based alternatives to BPA-based epoxy.

At Nerpa Polymers, we work on developing formulations where 20-50% of the BPA-based molecules are replaced with resin made from bioglycerol. 

Epichlorohydrin. A key component. 

In the epoxy manufacturing process, epichlorohydrin (ECH) is reacted with BPA to create an epoxy molecule. Our world would have looked completely different today if there had been no molecule like epichlorohydrin invented. The triangle-shaped structure in the picture below allows for the 95%+ of epoxy and significant percentage of other polymers to exist.

Epichlorohydrin triangle-shaped structure on the right side of the molecule is the key component of epoxy resin 

Safety concerns associated with Epichlorohydrin include its carcinogenic hazard and its irritant effects on the skin, eyes, and respiratory system. This molecule is also suspected of causing reproductive and developmental effects.

As with the BPA, the quality of raw materials and the technological process of epoxy resin production predetermine whether any free ECH is present in the product that arrives on the store shelve.

At Nerpa Polymers, we only use raw materials that have passed numerous quality control tests to protect our customers from harmful effects that could arise from negligent manufacturing processes leading to exposure to a free form of the molecules described in this blog post.

Did you know about the role of BPA and Epichlorohydrin in the epoxy production and safety concerns related to these compounds? Share your thoughts in the comments below!