You can freely build on How Disposable Diapers Keep Skin Dry Using Porous Plastic Sheets
This patent expired in 1987. 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
Procter and Gamble Co
Patent granted
1970
Expired
1987
Forward citations
133
What this patent covers
This patent describes a hydrophobic, porous plastic film used as the inner layer of a disposable diaper. The material is designed with specific hole patterns that allow urine to quickly pass through into an absorbent core. Because the material is hydrophobic, or water-repelling, it prevents the liquid from flowing back to the surface, effectively separating the moisture from the baby's skin. This mechanism was a fundamental shift from using cloth or non-porous materials that would trap wetness against the skin.
What is now free to use
All 0 claims of US 3489148 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 absorbent core material itself, only the top layer in contact with the skin.
Does not cover non-plastic or fabric-based top layers that rely on absorption rather than fluid transport through holes.
Does not cover diapers that do not use a hydrophobic material to prevent liquid back-flow.
Who is building on this today
Procter and Gamble continues to iterate on this technology, focusing on advanced non-woven materials and micro-apertures. Other major players like Kimberly-Clark have also built extensive patent portfolios around similar fluid-management layers in their Huggies product lines.
Products built on expired version of this technology
Pampers disposable diapers
Generic disposable diaper top sheets
How to cite this patent in your documentation
Procter and Gamble Co. US Patent 3489148. Topsheet for disposable diapers. Granted 1970, expired 1987. 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.