Patent US3989802A successfully refreshed from Google Patents.
US3989802A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of carbon fibers
Assignee: Akzo NV
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Filing: 1973-03-21
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Granted: 1976-11-02
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Expires: 1993-03-21
Abstract
Abstract Carbon fibers are surface oxidized by contacting the fiber with an aqueous solution comprising 5 - 20 weight percent sodium dichromate and 15 - 45 percent sulfuric acid for from one to sixty minutes at about the boiling point of the mixture. These fibers are useful in making resin-based composites by improving the adhesion between the fibers and the resin.
Inventors
- 👤 Louis A. Joo
- 👤 Roger Prescott
- 👤 Gordon E. Sharpe
- 👤 Frank E. Snodgrass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:55
CPC Classifications
D; D01; D01F; D01F11/00; D01F11/10; D01F11/12; D01F11/122; C; C08; C08K; C08K9/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
72 words
A method of treating high modulus acrylic-based carbon fibers which comprises contacting the fiber with an aqueous solution containing about 15 to about 35 percent by weight of sulfuric acid and about 7 to about 14 percent by weight of sodium dichromate or an equivalent thereof of a chromic acid producing salt at the refluxing temperature of the solution at normal sea level atmospheric pressure for about 1 to about 60 minutes.
Claim 2
Independent Claim
72 words
A method of treating high modulus acrylic-based carbon fibers which comprises contacting the fiber with an aqueous solution containing about 15 to about 35 percent by weight of sulfuric acid and about 7 to about 14 percent by weight of sodium dichromate or an equivalent thereof of a chromic acid producing salt at the refluxing temperature of the solution at normal sea level atmospheric pressure for about 1 to about 60 minutes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-11-02 | 1980-05-03 | 1980-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-02 | 1984-05-03 | 1984-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-02 | 1988-05-03 | 1988-11-02 | $7700.00 | Window Closed / Lapsed |