Bio-based polyols & biopolyurethanes

01Overview and value chain

Markers: [EC: USDA BioPreferred + EU REACH/ECHA isocyanate restrictions + ISCC PLUS Mass Balance | OECD: Bio-based materials, Industrial biotechnology | Regulator: EPA (USA), REACH (EU)]

Bio-based polyols are hydroxyl-functional intermediates synthesised by introducing –OH groups into the triglycerides of vegetable oils (soybean, castor, rapeseed, linseed) or into alternative aromatic feedstocks (lignin, cashew nutshell liquid). Reacted with (bio-)isocyanates, they yield biopolyurethanes — flexible and rigid foams, thermoplastic polyurethanes (TPU), coatings, adhesives and elastomers — that are 30–100% bio-derived versus their petrochemical analogues. Natural-oil polyol lines such as BASF’s Sovermol typically carry 80–100% bio-content, while bio-PDO chain extenders cut cradle-to-gate greenhouse-gas emissions by up to 86% versus fossil PDO. The global polyurethane market is projected to exceed $90 bn through 2026, and the US soy-polyol segment alone is forecast to grow from $487.6 M (2026) to $1,033 M (2035) at an 8.70% CAGR — so even partial bio-content substitution moves multi-billion-dollar procurement volumes. Hydroxyl values are tuned to 50–240 mg KOH/g to match flexible-foam, rigid-insulation or coating duties.

The key directions of bio-based polyols and biopolyurethanes are:

1. Vegetable-oil polyols (Soybean / Castor / Rapeseed / UCO Polyols): epoxidation of unsaturated fatty acids followed by acid-catalysed ring-opening with alcohols or diols — the workhorse route, supplying >80%-bio-content polyols for flexible foams, mattresses and automotive seating.
2. Bio-based diisocyanates (Bio-PDI): precision fermentation of lysine to 1,5-pentanediamine, then phosgene-free conversion to pentamethylene diisocyanate — the breakthrough that removes the last 100%-petrochemical half of a polyurethane, pioneered at 50 kt/yr scale in China.
3. Non-isocyanate polyurethanes (NIPU): reaction of cyclic carbonates (from epoxidised oils + captured CO2) with bio-based diamines, fully eliminating toxic phosgene and isocyanate chemistry — the EU-led response to ECHA isocyanate restrictions.
4. Lignin & CNSL polyols (Aromatic Bio-Polyols): partial hydrolysis of kraft/organosolv lignin or ethoxylation of cardanol from cashew nutshell liquid, delivering rigid aromatic backbones with inherent flame resistance and extreme hydrophobicity for marine coatings.

Sectoral value chain

[vegetable oils / lignin / CNSL] ──> [epoxidation + ring-opening] ──> [bio-polyols (B2B)]
                                              │
                                   (OH value 50–240 mg KOH/g)
                                              │
                                              ▼
[bio-PU foam / TPU / coating] <─── [reaction with bio-PDI / NIPU] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• Epoxidation + ring-opening chemistry (Epoxidation + Ring-Opening): peracid generation in situ from H2O2 and carboxylic acid over a cation-exchange resin, followed by acid-catalysed oxirane opening — controls OH value and functionality.
• Bio-PDO fermentation (Bio-PDO Fermentation): precision fermentation of corn-dextrose glucose to 1,3-propanediol (Susterra/Zemea), used as a chain extender and polytrimethylene ether glycol (PO3G) polyol.
• ISCC PLUS mass balance (ISCC PLUS Mass Balance): certified book-and-claim accounting that allocates renewable feedstock to bio-attributed PU grades (Desmopan EC, Sovermol) in existing asset bases.

02US

The US anchors the soy-polyol segment, leveraging the Midwest soybean crushing belt and federal procurement preference under USDA BioPreferred.

soy-polyol leadership, bio-PDO chain extenders, automotive + bedding demand

• Cargill BiOH polyols: epoxidised/hydroxylated soybean-oil polyols sold into mattress and automotive flexible foam (Room & Board upholstery, Ford seating), replacing a portion of petrochemical polyol.
• CovationBio PDO (ex–DuPont Tate & Lyle): 77,000 t/yr bio-PDO from regenerative Midwestern corn, processed in Loudon, TN — 86% lower carbon footprint (4.41 kg CO2 eq) than fossil PDO, 20 years in market.
• US soy-polyol market: $487.6 M in 2026, forecast to $1,033 M by 2035 at 8.70% CAGR, with EPA TSCA Section 5 pathways and USDA BioPreferred accelerating reformulation.

03CN

China is the global hub for bio-based diisocyanates, converting castor oil and fermented diamines into the world’s first fully bio-based PU elastomers and foams.

bio-PDI breakthrough, castor-oil mega-plants, state green-chemistry subsidies

• Cathay Biotech (688065.SH): precision-ferments lysine to bio-based pentanediamine (50 kt/yr, the PDI precursor) and long-chain dicarboxylic acids (115 kt/yr, DC10–DC18), plus bio-polyamides (100 kt/yr); 2025 Q3 revenue RMB 2.545 bn (+14.9%), 494 patents.
• Castor-oil polyol plants: large Zhejiang and Jiangsu facilities modify castor oil into polyols for the global sustainable-footwear sole supply chain.
• State subsidies: green-chemistry projects subsidised under national carbon-intensity-of-industry programmes, with GB indoor-air-quality standards tightening purity specs.

04EU

The EU leads on non-isocyanate polyurethanes (NIPU) and circular feedstocks, driven by ECHA restrictions on toxic isocyanates in construction foams and coatings.

NIPU R&D, UCO/animal-fat feedstocks, ISCC PLUS + OEKO-TEX certification

• Covestro bio-aniline + MDI: the €8.4 M EU-funded Bio4PURConti project (June 2026) targets the world’s first continuous bio-based aniline process for MDI, cutting up to ~20 Mt/yr of global fossil-aniline CO2; Desmopan EC TPU carries up to 60% biomass carbon (>20% lower footprint).
• BASF Sovermol polyols: natural-oil polyols (rapeseed/castor) at 80–100% bio-content for solvent-free industrial, marine and wind-power coatings.
• Circular feedstocks: used cooking oil (UCO) and technical animal fats epoxidised into polyols, avoiding food-vs-land competition; OEKO-TEX Standard 100 and CertiPUR govern eco-leather and furniture-foam emissions.

05Leading companies and research institutes

06Tech stack and innovations

The stack couples oleochemical polyol synthesis with a new generation of bio-based hard-segment monomers and non-isocyanate routes.

1. Epoxidation + ring-opening route (Epoxidation + Ring-Opening):
   • peracetic/formic acid generated in situ from 50% H2O2 over a cation-exchange resin at 50–70°C opens C=C bonds into oxiranes.
   • ring-opening with methanol gives flexible, low-functionality polyols; ethylene glycol or glycerol raises functionality for rigid foams — OH value targeted to 150 mg KOH/g.
2. Bio-PDO and bio-PDI hard segments (Bio-PDO / Bio-PDI):
   • corn-dextrose fermentation to 1,3-propanediol (PO3G polyol / chain extender), and lysine fermentation to 1,5-pentanediamine converted to pentamethylene diisocyanate.
   • case: Cathay Biotech’s 50 kt/yr pentanediamine enables 100%-bio-derived PU elastomers; CovationBio PDO cuts GHG 69% and non-renewable energy 60%.
3. Non-isocyanate polyurethanes (NIPU):
   • CO2-added cyclic carbonates from epoxidised oils react with bio-based diamines, yielding hydroxy-PU with no phosgene or free isocyanate.
   • residual –OH groups improve adhesion to metal and glass, suiting EU construction and coating uses under ECHA limits.

07Value chains and production pipelines

Industrial pipeline of soy-polyol-derived bio-PU flexible foam (ASTM D3574 / DIN EN 1024)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Oil purification & QC  │ ───> │ 2. Epoxidation            │
└───────────────────────────┘      └───────────────────────────┘
                                                 │
                                                 ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Ring-opening → polyol  │ <─── │ 3. Wash, neutralise, dry  │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. A-component + foaming  │ ───> │ 6. Curing + QA/QC         │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Oil purification and input QC

Soybean oil is filtered and bleached with activated clay; the iodine value must exceed 120 g I2/100 g (unsaturation) and the acid value stay below 1 mg KOH/g to protect downstream catalysts.

Stage 2: Epoxidation of triglycerides

Oil, formic acid and a cation-exchange resin are charged; 50% hydrogen peroxide is dosed over 3–4 h at 60°C with jacket cooling — the exotherm is held below 85°C to avoid gel-forming polymerisation.

Stage 3: Wash, neutralisation and vacuum drying

The resin is filtered out, the epoxidised oil is washed with deionised water and neutralised, then vacuum-dried at 90°C / 50 mbar to water content below 0.05%.

Stage 4: Ring-opening to polyol

The epoxide is reacted with methanol or ethylene glycol over phosphoric acid at 120°C for 4 h; excess alcohol is vacuum-stripped and the polyol is tuned to a hydroxyl value of ~150 mg KOH/g.

Stage 5: A-component preparation and foaming

The bio-polyol is blended with water (blowing agent) and amine catalyst, then mixed with bio-PDI isocyanate in a 150-bar high-pressure mix head and dispensed into a 50°C mould — start time 10–15 s, gel time 40–60 s.

Stage 6: Curing and QA/QC

The moulded foam is demoulded after 5 min and cured 24 h at room temperature; ASTM D3574 covers density, tensile strength and compression set, and fluctuation-chamber testing confirms no residual amine or isocyanate emissions before the bio-PU article ships.