Polyurethane Sustainability: Natural-Oil Polyols Derived from Cashew Nutshell Liquid (CNSL) Production
- ial
- Jun 12
- 3 min read
From Cashew Waste to Polyurethane Building Block
Cashew Nutshell Liquid (CNSL) is one of the most promising non-food renewable feedstocks for producing bio-based polyols used in polyurethane foams, coatings, adhesives, sealants, and elastomers. Unlike food-based biostocks such as soybean or palm oil-based polyols, CNSL is derived from an agricultural waste stream.
The natural composition of CNSL is a mix of 60%-70% anacardic acid, 2%-5% cardanol, and 10%-20% cardol. For industrial purposes, the production of polyols is usually based on cardanol (C15 unsaturated phenol).
Fig 1: Composition of Natural CNSL
Source: (Emilie Rojtman, 2024)
Turning CNSL into Cardanol-Based Polyols
The first step of the manufacturing process involves mechanical pressing, solvent extraction, roasting, and hot-oil bath extraction for the production of crude CNSL. For cardanol production, the crude CNSL undergoes decarboxylation of anacardic acid. The resultant product is then vacuum distilled and purified to give cardanol. Additional -OH groups are then added to the cardanol, as it only contains one hydroxyl group, via epoxidation, Mannich reaction, or oxyalkylation.
Fig 2: Production Process of Polyurethane Products from CNSL
Where CNSL Polyols Shine and Where They Fall Short
Cardanol-derived polyols employed in polyurethane foam production generally possess relatively low molecular weights, typically below 1000 g/mol. This characteristic promotes the formation of highly crosslinked polymer networks, making these materials particularly suitable for rigid polyurethane foam applications. Although extensive research has been conducted on cardanol-based monomers, the development and utilization of cardanol-derived polyether and polyester polyols for polyurethane synthesis remain limited. A few reasons for its limited adoption include limited hydroxyl functionality, low molecular weight and brittleness in rigid foams, higher viscosity after functionalisation, strong aromatic character, geographic limitations, etc.
Among the various cardanol-based intermediates investigated, Mannich-type polyols have emerged as the most extensively studied and commercially attractive candidates for polyurethane foam manufacturing. Their popularity can be attributed to their high hydroxyl functionality, enhanced reactivity toward isocyanates, and comparatively low viscosity, which facilitates processing and improved formulation performance.
Asia-Pacific's Quiet Dominance in the NOP Race
Globally, the Asia-Pacific region leads in the production of Cashew Nut Shell Liquid (CNSL), accounting for more than 80% of the global CNSL production capacity, driven by its large cashew-processing industry.
The top three exporters of CNSL are Vietnam, India, and Nigeria. China imports a significant amount of CNSL from these regions, particularly from India and Vietnam. At present, only a handful of producers, mostly in China, have successfully formulated CNSL-based polyols into the production of polyurethane foam. However, its commercialisation is still at nascent stages.
Therefore, in our study Global Overview of Sustainability in Polyurethane Industry 2021-2035, we have included the production of CNSL-based polyols in the Natural Oil Polyols (NOPs) segment. The overall market of NOPs also faces challenges from the expansion of chemical recycling and mass-balanced polyols, reducing its market share from more than 30% in 2025 to less than 25% in 2035. The trend of NOP production and its market share compared to other eco-friendly polyol production in the APAC region from 2021 to 2035 is shown in the graph below:
Source: IAL Consultants
A Niche Today, A Contender Tomorrow
The dominance of Asia in the production of CNSL is supported by the production of cashew cultivation and processing. With key regions such as India and Vietnam forming the backbone of the CNSL supply chain, the APAC region has the potential to dominate the market. The presence of integrated supply chains, low cost of production, abundant raw material, and strong downstream segments support the growth of the market.
APAC currently has a geographical advantage for the expansion of CNSL-based polyols in polyurethane products. However, the adoption of CNSL-derived cardanol polyols in the production of sustainable polyurethane applications faces several limitations, some chemical and some infrastructure-based.
Overall, the natural oil polyols segment is expected to showcase significant development in the upcoming years and is expected to grow at a CAGR of 30% between 2025 and 2035.
Research for this study was carried out in late 2025 and early 2026. Data are provided from 2021 to 2035, with the base year 2025.
To learn more about the report, please follow the link
For more information, please contact ial@brggroup.com
IAL Consultants (A Division of BRG Enterprise Solutions Ltd)
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