US4401533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface-treatment of carbon fiber
Assignee: Teijin Ltd
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Filing: 1981-03-05
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Granted: 1983-08-30
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Expires: 2001-03-05
Abstract
Abstract A method for producing carbon fibers exhibiting excellent adhesive properties to resins and having high strength and heat-oxidation resistance, comprising electrically treating high strength carbon fiber in an aqueous solution of a sulfuric acid salt under conditions such that the current density is from about 0.05 to 0.5 A/m 2 and the product of current density, voltage, and processing time is from about 0.02 to 8 A-V-min/m 2 , while continuously moving the carbon fiber as an anode in the aqueous solution.
Inventors
- 👤 Kazuhisa Saito
- 👤 Hiroyasu Ogawa
- 👤 Tetsuro Shigei
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:19
CPC Classifications
C; C25; C25F; C25F1/00; C25D; C25D11/00; D; D01; D01F; D01F11/00; D01F11/10; D01F11/12; D01F11/122; D01F11/16; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2918
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
107 words
A method for surface-treating high strength carbon fiber comprising passing an electrical current through the carbon fiber in an aqueous solution of a sulfate under conditions such that the current density is from about 0.05 to 0.5 amps/meter 2 (A/m 2 ), and the product of the current density, voltage (V), and processing time (min) is from about 0.02 to 8 A-V-min/m 2 , while continuously moving the carbon fiber as an anode in the aqueous solution, wherein the high strength carbon fiber has a tensile modulus of from about 20,000 to 28,000 Kg/mm 2 and a tensile strength of at least about 250 Kg/mm 2 .
Claim 2
Independent Claim
107 words
A method for surface-treating high strength carbon fiber comprising passing an electrical current through the carbon fiber in an aqueous solution of a sulfate under conditions such that the current density is from about 0.05 to 0.5 amps/meter 2 (A/m 2 ), and the product of the current density, voltage (V), and processing time (min) is from about 0.02 to 8 A-V-min/m 2 , while continuously moving the carbon fiber as an anode in the aqueous solution, wherein the high strength carbon fiber has a tensile modulus of from about 20,000 to 28,000 Kg/mm 2 and a tensile strength of at least about 250 Kg/mm 2 .
Claim 3
Dependent Claim
29 words
A method as in claim 1 wherein the sulfate is at least one member selected from the group consisting of ammonium sulfate, ammonium hydrogensulfate, sodium sulfate, and sodium hydrogensulfate.
Claim 4
Dependent Claim
25 words
A method as in claim 1 wherein the sulfate is at least one member selected from the group consisting of ammonium sulfate and ammonium hydrogensulfate.
Claim 5
Dependent Claim
19 words
A method as in claim 1 wherein the current density is from about 0.1 to 0.4 A/m 2 .
Claim 6
Dependent Claim
22 words
A method as in claim 1 wherein the temperature of the aqueous sulfate solution is from about 10° C. to 60° C.
Claim 7
Dependent Claim
24 words
A method as in claim 1 wherein the concentration of the sulfate in the aqueous solution is from about 1% to 15% by weight.
Claim 8
Dependent Claim
16 words
A method as in claim 1 wherein the voltage is from about 1 to 20 volts.
Claim 9
Dependent Claim
16 words
A method as in claim 1 wherein the carbon fiber is produced from an acrylic fiber.
Claim 10
Dependent Claim
24 words
A method as in claim 1 wherein after the electrical treatment the carbon fiber is washed with water to remove the sulfuric acid salt.
Claim 11
Dependent Claim
28 words
A method as in claim 10 wherein the water-washing is performed until the amount of the sulfate remaining on the carbon fiber is about 2,000 ppm or less.
Claim 12
Dependent Claim
119 words
A carbon fiber exhibiting excellent adhesive properties to resins and having high strength and heat-oxidation resistance produced by a method comprising passing an electrical current through the carbon fiber in an aqueous solution of a sulfate under conditions such that the current density is from about 0.05 to 0.5 amps/meter 2 (A/m 2 ), and the product of the current density, voltage (V), and processing time (min) is from about 0.02 to 8 A-V-min/m 2 , while continuously moving the carbon fiber as an anode in the aqueous solution, wherein the high strength carbon fiber has a tensile modulus of from about 20,000 to 28,000 Kg/mm 2 and a tensile strength of at least about 250 Kg/mm 2 .
Claim 13
Dependent Claim
119 words
A carbon fiber exhibiting excellent adhesive properties to resins and having high strength and heat-oxidation resistance produced by a method comprising passing an electrical current through the carbon fiber in an aqueous solution of a sulfate under conditions such that the current density is from about 0.05 to 0.5 amps/meter 2 (A/m 2 ), and the product of the current density, voltage (V), and processing time (min) is from about 0.02 to 8 A-V-min/m 2 , while continuously moving the carbon fiber as an anode in the aqueous solution, wherein the high strength carbon fiber has a tensile modulus of from about 20,000 to 28,000 Kg/mm 2 and a tensile strength of at least about 250 Kg/mm 2 .
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) | 1986-08-29 | 1987-02-28 | 1987-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-29 | 1991-02-28 | 1991-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-29 | 1995-02-28 | 1995-08-30 | $7700.00 | Window Closed / Lapsed |