You can freely build on How Wallace Carothers Invented Nylon

What this patent covers

This patent describes the chemical synthesis of high-molecular-weight linear polyamides by heating diamines with dibasic acids. By controlling the polymerization process, the inventor created long-chain molecules that could be drawn into strong, flexible fibers. This process transformed simple chemical building blocks into a material capable of replacing natural silk in textiles and industrial applications.

What is now free to use

All 0 claims of US 2130523 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover non-linear or branched polyamide structures.

• Does not cover the specific manufacturing machinery used for spinning the fibers.

• Does not cover the use of polyamides in non-fiber applications like molded plastics.

Who is building on this today

DuPont remains a major player in the polyamide market, but the core chemistry is now foundational knowledge used by global chemical giants like BASF and Lanxess to produce various grades of nylon for automotive and industrial parts.

Products built on expired version of this technology

How to cite this patent in your documentation

EI Du Pont de Nemours and Co. US Patent 2130523. Linear polyamides and their production. Granted 1938, expired 1955. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.