You can freely build on How DuPont Invented Neoprene Synthetic Rubber
This patent expired in 1951. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
EI Du Pont de Nemours and Co
Patent granted
1934
Expired
1951
Forward citations
7
What this patent covers
The patent outlines a chemical process for polymerizing chlorobutadiene, a liquid monomer, into a solid, rubber-like material. By controlling the reaction conditions, the process creates a synthetic elastomer that mimics the properties of natural rubber but offers superior resistance to oils, heat, and weathering. This invention allowed for the mass production of a stable, elastic substance that could be molded or shaped for industrial use.
What is now free to use
All 0 claims of US 1967861 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 the synthesis of natural rubber derived from latex trees.
Does not cover other types of synthetic rubbers like styrene-butadiene (SBR).
Does not cover the specific vulcanization additives used in finished consumer goods.
Who is building on this today
DuPont remained the primary manufacturer of Neoprene for decades, though the patent eventually expired, allowing other chemical giants like Denka and Lanxess to enter the market.
Products built on expired version of this technology
Wetsuits for surfing and diving
Automotive fan belts and hoses
Protective industrial gloves
Laptop sleeves and cases
How to cite this patent in your documentation
EI Du Pont de Nemours and Co. US Patent 1967861. Process of polymerizing chlorobutadiene and resulting product. Granted 1934, expired 1951. 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.