Nylon — The First Synthetic Fiber, Invented at DuPont
Wallace Carothers' 1937 DuPont patent describes nylon — the world's first fully synthetic textile fiber, created from coal, water, and air, which launched the synthetic materials industry.
Original patent title: “Synthetic fiber”
What this patent covers
The actual claim
This patent describes a method for creating polyamide fibers — long-chain polymer molecules made by reacting diamines with dibasic acids (or their derivatives). The key process is melt-spinning: the polymer is melted, forced through tiny holes in a metal plate (a spinneret), and then drawn out as thin fibers that solidify as they cool. As the fibers are drawn under tension, the polymer chains align along the fiber's axis, dramatically increasing tensile strength and elasticity. The result is a strong, flexible, smooth fiber that can be woven into fabric. Unlike natural fibers (cotton, silk, wool), nylon's properties are controlled entirely by the chemical composition and manufacturing process — the same chemistry that makes fishing line strong makes hosiery sheer.
What this patent does NOT cover
The boundaries
- Polyester fiber (Dacron) — a different polymer chemistry developed by British chemists in 1941
- Aramid fibers like Kevlar — a related but much stronger polyamide structure developed later at DuPont
- Nylon's use in engineering plastics (gears, bearings, structural parts) — the patent covers fiber, not molded forms
- The specific nylon-6 chemistry — Carothers' patent covers nylon-6,6 (from hexamethylenediamine + adipic acid); nylon-6 is a different but related polymer
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
Silk was the luxury fiber of the ancient world — strong, smooth, and lustrous, but dependent on silkworms and expensive to produce. Carothers set out to understand why natural polymers (silk, rubber, cellulose) had such useful properties, by synthesizing simpler artificial versions and studying their structure. The insight was that extremely long molecular chains — polymerization — were responsible. If you could create long enough chains, you could mimic or exceed natural materials. Nylon-6,6's specific structure gives it both strength (from the aligned chain structure when drawn) and a smooth feel (from its chemical regularity). DuPont announced nylon stockings to the public in 1939; 64 million pairs sold in the first year. Carothers died by suicide in 1937, the year his patent was filed, and never saw the product go to market.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
DuPont launched nylon stockings on May 15, 1940 — 'N-Day' — and sold 4 million pairs in the first few hours; the term 'nylons' for hosiery dates from this launch
During World War II, all nylon production was diverted to military use: parachutes, ropes, tents, and aircraft fuel tanks
Today nylon is used in toothbrushes, fishing line, guitar strings, airbags, zip ties, and performance athletic wear — a $35 billion global market
Why it matters
The bigger picture
Nylon was the proof-of-concept that synthetic materials could replace natural ones — and do it better. It launched DuPont's slogan 'Better Living Through Chemistry' and opened the era of polymer science that gave us polyester, Spandex, Kevlar, Gore-Tex, and thousands of other materials. Carothers was one of the most brilliant chemists of the 20th century; his fundamental research into polymer structure underpins all of modern plastics and synthetic fiber science. He never received credit during his lifetime — DuPont kept his work secret to protect competitive advantage, and he struggled with depression throughout his career.
Filed
April 9, 1937
Granted
September 20, 1938
Claim 1 — Plain English
What this patent covers
This patent describes a method for creating polyamide fibers — long-chain polymer molecules made by reacting diamines with dibasic acids (or their derivatives). The key process is melt-spinning: the polymer is melted, forced through tiny holes in a metal plate (a spinneret), and then drawn out as thin fibers that solidify as they cool. As the fibers are drawn under tension, the polymer chains align along the fiber's axis, dramatically increasing tensile strength and elasticity. The result is a strong, flexible, smooth fiber that can be woven into fabric. Unlike natural fibers (cotton, silk, wool), nylon's properties are controlled entirely by the chemical composition and manufacturing process — the same chemistry that makes fishing line strong makes hosiery sheer.
The clever bit
Silk was the luxury fiber of the ancient world — strong, smooth, and lustrous, but dependent on silkworms and expensive to produce. Carothers set out to understand why natural polymers (silk, rubber, cellulose) had such useful properties, by synthesizing simpler artificial versions and studying their structure. The insight was that extremely long molecular chains — polymerization — were responsible. If you could create long enough chains, you could mimic or exceed natural materials. Nylon-6,6's specific structure gives it both strength (from the aligned chain structure when drawn) and a smooth feel (from its chemical regularity). DuPont announced nylon stockings to the public in 1939; 64 million pairs sold in the first year. Carothers died by suicide in 1937, the year his patent was filed, and never saw the product go to market.
What it does not cover
- Polyester fiber (Dacron) — a different polymer chemistry developed by British chemists in 1941
- Aramid fibers like Kevlar — a related but much stronger polyamide structure developed later at DuPont
- Nylon's use in engineering plastics (gears, bearings, structural parts) — the patent covers fiber, not molded forms
- The specific nylon-6 chemistry — Carothers' patent covers nylon-6,6 (from hexamethylenediamine + adipic acid); nylon-6 is a different but related polymer
Patent Journey
From filing to expiry
Patent Filed
1937
Patent Granted
1938 · 1yr after filing
Highly Cited
430 patents cite this
Patent Expired
1957
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
0/20
Narrow claims
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assignee
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Glossary
Key terms defined
- drawing
- Stretching fibers after extrusion to align polymer chains, dramatically increasing strength and reducing diameter
- polyamide
- A polymer where the repeating units are linked by amide bonds (CO-NH) — nylon is the most famous polyamide
- spinneret
- The metal plate with tiny holes through which molten polymer is extruded to form fibers — named after the spinnerets of spiders
- melt-spinning
- The process of forcing melted polymer through tiny holes to form fibers, then drawing them under tension to align the molecular chains
Citations
Patent lineage
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