The Teflon Patent, Read Back in the PFAS-Regulation Era

Note on this format: This memo records what I confirmed at the patent URL, with Claim 1, inventor, assignee, and dates retrieved from Google Patents. The full specification (examples, experimental data) and litigation history (PFOA-related) are unread. Verified facts only; speculation is labeled as such.

Why Dig This

"The Teflon pan" is a 20th-century kitchen icon, but PTFE (polytetrafluoroethylene) starts in a 1938 lab accident during refrigerant research. In 2026, with fluoropolymers at the center of the PFAS regulatory debate, it's worth re-reading the substance patent's Claim 1 to see what it actually covers. The point of the dig is to anchor the distinction between "PTFE finished product" and "PFOA processing aid" in the primary source.

Patent Basics

• Patent number: US2230654A
• Title: Tetrafluoroethylene polymers
• Filed: July 1, 1939 (priority same date)
• Granted: February 4, 1941
• Inventor: Roy J. Plunkett (sole)
• Original assignee: Kinetic Chemicals Inc. (Wilmington, Delaware) — a DuPont and General Motors joint venture for refrigerant manufacture
• Primary source: Google Patents (URL confirmed; Claim 1 retrieved)
• Legal status: Expired around 1958 (17-year term). Kinetic Chemicals was fully acquired by DuPont in 1949, consolidating final ownership at DuPont.

Claim 1 (Verbatim)

Polymerized tetrafluoroethylene.

Three words. The patent claims the polymer of tetrafluoroethylene (TFE, CF2=CF2) as a substance — a textbook example of a minimal substance-patent claim.

How It Was Discovered (from Specification and Oral History)

On April 6, 1938, Plunkett (age 27) was at DuPont's Jackson Laboratory (Deepwater, NJ), working on alternatives to existing Freon refrigerants. He noticed a TFE gas cylinder that "looked empty but still weighed full." When he cut the cylinder open, he found a white waxy solid coating the inside — TFE had spontaneously polymerized at room temperature under pressure into PTFE. He reproduced the reaction conditions, characterized the polymer's properties, and filed this patent in July 1939.

Database Correction: Original Assignee Is Kinetic Chemicals

The candidates.tsv entry reads "DuPont, Roy J. Plunkett (1938 accidental discovery)." In fact the original assignee is Kinetic Chemicals Inc., the DuPont/GM joint venture, not DuPont directly. Adding to the database-correction sequence from Day 8 onward (IC-009/011/012, PH-001 through PH-007). Inventor and discovery year match the database.

Connections to Today (Hypothesis)

Pitfalls

"Teflon = PFAS = dangerous" is a conflation. The PFAS species attracting regulatory attention are typified by PFOA (perfluorooctanoic acid, C8), produced by 3M from 1947 onward and used as a surfactant in PTFE polymerization. The PTFE finished product and the PFOA processing aid are chemically distinct and should be evaluated separately. This memo is limited to confirming Claim 1 in the primary source; PFOA litigation history is reserved for a later full-note treatment.

Unconfirmed

• Full specification text (examples, experimental data) verbatim
• Forward citation count
• Plunkett's original lab notebooks (held at the DuPont Hagley Museum & Library)
• Primary records of PFOA-related litigation (DuPont Washington Works, 3M Cottage Grove)
• Manhattan Project Oak Ridge K-25 PTFE adoption records (declassified files)

Next Action

When promoting this to a full note, retrieve (a) the full specification's example sections, (b) Plunkett's lab notebooks at the Hagley Museum, (c) primary documents from PFOA litigation, and trace the PTFE-to-PFOA distinction across the lineage.

Sources:

• Primary patent: US2230654A on Google Patents
• Food & Health Patent #4 (full note): Aspartame US3492131A
• Wikipedia: Polytetrafluoroethylene (https://en.wikipedia.org/wiki/Polytetrafluoroethylene)