Since their invention by Paul Schlack (Germany) in 1934, epoxy resins have come a long way finding applications in a variety of segments. In the coatings industry, they are one of the most popular resins due to their ability to form films that show excellent corrosion resistance, chemical resistance, and adhesion. In construction applications, epoxy systems can help prolong lifespan of structures due to their toughness and durability. In adhesive applications, they are sought for their ability to bond with diverse substrates such as metal, wood, glass, and stone. More recently, they have found applications in composites which have potential to replace metal structures.

Due to their versatility, the epoxy resins market is huge, and as per a market report by Polaris Market Research, they had a global market size of US$ 6.1 billion in 2020 that is estimated to grow to US$ 10.22 billion by 2029 at a CAGR of 6.4%. In a stark contrast, the global biobased epoxy resin market was valued at US$ 47.4 million in 2019 and is estimated to grow to US$ 117.0 million by 2027 at a CAGR of 12.1%. Although this growth rate is encouraging, majority of epoxy resins are still petroleum-derived and as the estimates show, their demand is ever growing. Bio-based epoxies show promise to reduce our dependance on depleting natural resources by replacing petrochemicals with renewable and sustainable alternatives, but their path to widespread use has only just begun.

Commercially available Biobased Epoxy Resins:

1. Vegetable oil-based epoxies dominate the biobased epoxy market. These vegetable oils include, soybean oil, linseed oil, hemp oil and cotton seed oil, to name a few. Among these, the most popular is soybean oil, a renewable agricultural product that is abundant and cheap due to its high global production, making it a good candidate to replace petrochemicals. Epoxidized vegetable oils can be crosslinked with epoxy curing agents such as amines. The major drawback of these systems is poor mechanical properties that may be because of the high content of fatty chains of oils and poor chemical resistance due to the presence of weaker ester bonds compared to ether linkages in traditional epoxy systems.
2. Cardanol-based epoxy resins are now commercially gaining attention. Cardanol is a phenol that is obtained from the cashew shell, which is a by-product of processing cashews. Due to its many reactive sites, cardanol can be chemically modified to include epoxy groups, which can then be cured with epoxy curing agents. These resins show high hydrophobicity and excellent corrosion resistance as a virtue of cardanol’s intrinsic properties. The drawback of these resins is their yellow colour which may limit the possible shades of paint made from them.At NSPC, our NEOPOXY^TM resins are cardanol-based epoxies for 2 pack systems that are a greener alternative to traditional epoxies. With their lower requirement of hardeners, they further help in reducing the carbon footprint.SOLOPOXY^TM resins are a very unique type of 1 pack cardanol-based epoxy resins that do not require any curing agents to crosslink. This high biomass content resin consumes atmospheric oxygen to form high-performance films.
3. Furan-based epoxies resins are another segment of biobased epoxies that have now started to be commercially available. These resins are prepared from furfural obtained from cellulose and hemicellulose, which are agricultural wastes produced when processing oats, corn, wheat or rice. When crosslinked with epoxy curing agents, these resins show excellent thermal stability and strength. However, their widespread use has been hindered by their potential risk to human and environmental health since furfural has been found to be carcinogenic to lab animals.
4. Other biobased epoxy resins that show promise are based on, but not limited to – lignin, rosin, gallic acid, itatonic acid and vanillin. Studies show that these resins can replace petroleum derived epoxies, but their commercialization has been difficult due to various scalability issues.

These technological advances towards sustainability are exciting and encouraging. They would ensure a future where the demands of the coming generations are met despite the depletion of natural resources that we currently take for granted. At NSPC, we feel inspired by the work done around the world towards a greener tomorrow and we are committed to contribute our fair share to advance the polymeric materials sphere towards sustainability.

References:

[1] Schlack, P., “Manufacture of amines of high molecular weight, which are rich in nitrogen”. German Patent 676117, U.S. Patent 2,136,928 (1938)

[2] May, Clayton, “Epoxy Resins: Chemistry and Technology (2nd ed.). CRC Press. ISBN 978-1-351-44995-3 (2018)

[3] https://www.chemicalsafetyfacts.org/chemicals/epoxy-resins

[4] https://www.polarismarketresearch.com/industry-analysis/epoxy-resins-market

[5] https://www.polarismarketresearch.com/industry-analysis/bio-based-epoxy-resins-market

[6] Kumar, S, et al., “Recent Development of Biobased Epoxy Resins: A Review, Polymer-Plastics Technology and Engineering”, 57:3, 133-155 (2018). Link: https://doi.org/10.1080/03602559.2016.1253742

[7] Baroncini, E. A., et al. “Recent advances in bio‐based epoxy resins and bio‐based epoxy curing agents.” Journal of Applied Polymer Science 133.45 (2016)

To further understand the various types of bio-based epoxy resins, their properties, and commercial availability, you can visit NSPC’s website https://www.nadkarnispc.com/products. NSPC is a leading provider of bio-based epoxy resins and other materials that are sustainable, renewable, and eco-friendly.