US3933986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing carbon fibers
Assignee: Sumika Hercules Co Ltd
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Filing: 1974-04-11
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Granted: 1976-01-20
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Expires: 1994-04-11
Abstract
Abstract A process for producing carbon fibers which comprises (a) treating preoxidized fibers produced from an acrylonitrile fiber with a reducing liquid containing a specific compound and (b) thereafter carbonizing or graphitizing the treated fibers at a temperature above 800° C. The thus-obtained carbon or graphite fibers have a high tensile strength and a high modulus of elasticity.
Inventors
- 👤 Yasuo Matsumura
- 👤 Soichiro Kishimoto
- 👤 Masahiko Ozaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:57
CPC Classifications
D; D01; D01F; D01F9/00; D01F9/08; D01F9/12; D01F9/14; D01F9/32; C; C01; C01B; C01B32/00; D01F9/20; D01F9/21; D01F9/22
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
84 words
A process for producing carbon fibers which comprises (a) treating preoxidized fibers produced by heating acrylonitrile fibers in an oxygen-containing atmosphere at a temperature between 150°C and 400°C with a reducing liquid containing at least one compound selected from the group consisting of thiosulfuric acid, polythionic acid, dithionic acid, sulfurous acid, pyrosulfurous acid dithionous acid (H 2 S 2 O 4 ) and their salts, and (b) thereafter carbonizing or graphitizing the thus treated fibers in a non-oxidizing atmosphere at a temperature above 800°C.
Claim 2
Dependent Claim
84 words
A process for producing carbon fibers which comprises (a) treating preoxidized fibers produced by heating acrylonitrile fibers in an oxygen-containing atmosphere at a temperature between 150°C and 400°C with a reducing liquid containing at least one compound selected from the group consisting of thiosulfuric acid, polythionic acid, dithionic acid, sulfurous acid, pyrosulfurous acid dithionous acid (H 2 S 2 O 4 ) and their salts, and (b) thereafter carbonizing or graphitizing the thus treated fibers in a non-oxidizing atmosphere at a temperature above 800°C.
Claim 3
Dependent Claim
28 words
The process for producing carbon fibers as claimed in claim 1 wherein the reducing liquid is an aqueous solution containing a dithionite salt and a β-anthraquinone sulfonate salt.
Claim 4
Dependent Claim
35 words
The process as claimed in claim 1 wherein the preoxidized fibers after being subjected to reducing liquid treatment are introduced into a carbonizing furnace without contact with the outer atmosphere and then carbonized or graphitized.
Claim 5
Dependent Claim
22 words
The process for producing carbon fibers as claimed in claim 1 wherein the reducing liquid is maintained at a pH above 10.
Claim 6
Dependent Claim
28 words
The process for producing carbon fibers as claimed in claim 1 wherein the reducing compound in the reducing liquid is in concentration of 1 to 50% by weight.
Claim 7
Dependent Claim
22 words
The process for producing carbon fibers as claimed in claim 1 wherein the reducing liquid is maintained at a temperature below 100°C.
Claim 8
Dependent Claim
20 words
The process for producing carbon fibers as claimed in claim 1 wherein the reducing liquid contains water as the medium.
Claim 9
Dependent Claim
24 words
The process as claimed in claim 1 characterized in that the preoxidized fibers are treated for 1 to 60 minutes in the reducing liquid.
Claim 10
Dependent Claim
43 words
The process for producing carbon fibers as claimed in claim 1 wherein the acrylonitrile fiber is a fiber made from an acrylonitrile homopolymer or an acrylonitrile copolymer containing acrylonitrile in an amount of at least 80 mol % and another ethylenically unsaturated compound.
Claim 11
Dependent Claim
30 words
The process for producing carbon fibers as claimed in claim 9 wherein the acrylonitrile fiber is a fiber made from an acrylonitrile copolymer containing at least 90 mol % acrylonitrile.
Claim 12
Dependent Claim
17 words
The process for producing carbon fibers as claimed in claim 1 wherein the oxygen-containing atmosphere is air.
Claim 13
Dependent Claim
17 words
The process for producing carbon fibers as claimed in claim 1 wherein the non-oxidizing atmosphere is nitrogen.
Claim 14
Dependent Claim
44 words
The process for producing carbon fibers as claimed in claim 1 wherein the treated fibers are carbonized in a non-oxidizing atmosphere at a temperature of from 800° to 2000°C. and thereafter graphitized in a non-oxidizing atmosphere at a temperature of from 2000° to 3500°C.
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) | 1979-01-19 | 1979-07-21 | 1980-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-19 | 1983-07-21 | 1984-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-19 | 1987-07-21 | 1988-01-20 | $7700.00 | Window Closed / Lapsed |