Nylon (PA6, PA66): Production route
One monomer or two: how PA6 and PA66 differ
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Nylon is a family of polyamides. PA6 is made from one monomer, caprolactam, by ring-opening polymerisation and is the volume product. PA66 is made from two, adipic acid and HMDA. The HMDA comes from adiponitrile (ADN), long made only by Invista, Ascend, Asahi Kasei and Butachimie; Chinese ADN plants started from 2022 (indicative), removing the bottleneck. Specialty polyamides (PA11, PA12, PA46, PPA) are small but high value.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| PA6 by caprolactam ring-opening | about 72% of nylon volume (indicative) | about 1.0-1.02 t caprolactam per t PA6 (indicative) | 50-300 kt/yr chip plants; Chinese leaders over 500 kt/yr | about 98% after monomer recycle (indicative) | ammonium sulphate from upstream caprolactam (caprolactam tile) | caprolactam about CNY8,600/t (East China, Nov 2025) plus about $100-150/t conversion (indicative) |
| PA66 by adipic acid and HMDA polycondensation | about 28% of nylon volume (indicative) | about 0.65 t adipic acid and 0.51 t HMDA per t PA66 (stoichiometric) | 50-200 kt/yr; Invista Shanghai added 80 kt/yr and 130 kt/yr in 2024 (Mysteel) | over 98% (indicative) | water | not published; HMDA is the main cost driver (indicative) |
| Adiponitrile routes (for HMDA) | butadiene route the majority (indicative) | about 0.5 t butadiene and 0.5 t HCN, or about 1.0 t acrylonitrile, per t ADN (indicative) | 200-500 kt/yr ADN plants | not published | methylglutaronitrile and other nitriles | not published |
| Specialty polyamides (PA11, PA12, PA46, PPA) | about 3-5% of polyamide volume (indicative) | varies | 10-100 kt/yr | not published | varies | several times PA6 price (indicative) |
How each route works
PA6 by caprolactam ring-openingMolten caprolactam with a little water is polymerised at about 250-270 C in a VK tube. About 10% unreacted monomer and oligomer is extracted with hot water and recycled. Chips are dried and spun or compounded. Most plants are integrated with caprolactam.
Simple and cheap; lower melting point (about 220 C) than PA66.
Chemical Week Nov 2025 via caprolactam tile; indicative PA66 by adipic acid and HMDA polycondensationAdipic acid and HMDA are neutralised in water to nylon salt (AH salt), concentrated and polymerised in batch autoclaves or continuous reactors at about 270-290 C, releasing water.
Higher melting point (about 260 C) and stiffness; depends on scarce ADN technology.
Mysteel, May 2024; indicative Adiponitrile routes (for HMDA)Butadiene hydrocyanation adds hydrogen cyanide to butadiene with nickel catalysts (Invista, and Chinese licensees); acrylonitrile electrohydrodimerisation couples two acrylonitrile molecules electrically (Ascend, Asahi Kasei). ADN is hydrogenated to HMDA.
Hard to master; for decades it set the PA66 supply ceiling.
S&P Global CEH HMDA/ADN abstract (scope); indicative Specialty polyamides (PA11, PA12, PA46, PPA)PA11 is made from castor-oil-derived aminoundecanoic acid (Arkema); PA12 from laurolactam (Evonik); polyphthalamides from terephthalic acid. Used in fuel lines, 3D printing and high-heat electronics.
High performance and some bio-based; small and costly.
indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.