The global unsaturated polyester resin (UPRs) market is estimated to be USD 9.6 billion in 2021 and projected to reach USD 12.9 billion by 2026. Accordingly, a 10% market penetration represents a billion dollar annual opportunity. Furthermore, using a rough estimate of ~1 USD/lb and ~2 kg CO2 emitted per 1 kg of virgin resin produced provides an estimate that UPRs are responsible for 10 million metric tons of CO2 emissions per year. Castable, reactive resins represent a fruitful area for both economic and environmental gains.

UPRs are a broad class of materials with considerable variation in their formulations that enable them to serve in many applications. In general terms, they consists of about 24 wt% unsaturated polyester, about 2 wt% catalyst and pigments, and 74 wt% styrene. There are also acrylic based systems that share many features with UPRs; for example, polymethylmethacrylate (PMMA) may be disolved in methylmethacrlate (MMA) to made a castable resin. Again, in general terms, 30-40 wt% PMMA is dissolved in MMA with 2 wt.% catalysts/cross-linking agents/additives.

One important application of such reactive systems is in the manufacturing of engineering stone products. Engineered stone refers to artificially made, highly mineral-filled polymeric materials that are cast and hardened to form solids of various shapes having a wide variety of pigmentation and patterning. Engineered stone is utilized in the construction of countertops and sinks in both bathrooms and kitchens and more broadly for interior countertops and decorative surfaces.

Here, we report on our newly developed castable and curable resin system containing 40 wt% biobased materials. Elementary embedded energy and GHG LCA calculations demonstrate marked improvement over existing materials and an ability to decrease costs relative to present generation materials. The new formulations have been tested and demonstrated to be suitable for making solid surfacing and other engineered stone products.

Engineered stone products are one application area for greener reactive resin systems.

Harshal Bambhania

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