US4374114A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the surface modification of carbon fibers
Assignee: SUBJECT TO AGREEMENT RECITED SEE DOCUMENT FOR DETAILS
•
Filing: 1981-01-05
•
Granted: 1983-02-15
•
Expires: 2001-01-05
Abstract
Abstract An improved continuous hot gas surface modification process for carbon fibers is provided. The carbon fibers undergoing such processing are passed for a relatively brief residence time through a surface treatment zone to which continuously is fed nitrogen dioxide and air under conditions which have been found to produce a surprisingly effective surface modification. The resulting carbon fibers exhibit a significantly enhanced surface area and an improved ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength originally exhibited. When incorporated in a resinous matrix material, a fiber reinforced composite article of enhanced interlaminar shear strength is formed.
Inventors
- 👤 Sang N. Kim
- 👤 Paul E. McMahon
- 👤 John P. Riggs
- 👤 John M. Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:13
CPC Classifications
D; D01; D01F; D01F11/00; D01F11/10; D01F11/12; D01F11/122
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
138 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 90 percent carbon by weight so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 300° to 800° C. a gaseous atmosphere comprising approximately 1 to 25 percent by volume nitrogen dioxide and approximately 75 to 99 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 20 to 180 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 2
Dependent Claim
138 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 90 percent carbon by weight so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 300° to 800° C. a gaseous atmosphere comprising approximately 1 to 25 percent by volume nitrogen dioxide and approximately 75 to 99 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 20 to 180 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 3
Dependent Claim
36 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification contains at least 93 percent carbon by weight.
Claim 4
Dependent Claim
36 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification contains at least 99 percent carbon by weight.
Claim 5
Dependent Claim
35 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification includes a substantial quantity of graphitic carbon.
Claim 6
Dependent Claim
71 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification is derived from an acrylic fibrous material selected from the group consisting of an acrylonitrile homopolymer and acrylonitrile copolymers which contain at least 85 mole percent acrylonitrile units and up to about 15 mole percent of one or more monovinyl units copolymerized therewith.
Claim 7
Dependent Claim
31 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein the carbonaceous fibrous material is derived for a pitch fibrous material.
Claim 8
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament yarn.
Claim 9
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament tow.
Claim 10
Dependent Claim
50 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said gaseous atmosphere which is fed to said surface treatment zone comprises approximately 2 to 10 percent by volume nitrogen dioxide, and approximately 90 to 98 percent by volume air.
Claim 11
Dependent Claim
62 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 1 wherein said carbonaceous fibrous material which undergoes surface modification exhibits an average single filament tensile strength of at least 200,000 psi prior to said surface modification, and retains at least 70 percent of said average single filament tensile strength following said surface modification.
Claim 12
Dependent Claim
153 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 90 percent carbon by weight and exhibiting an average single filament Young's modulus of approximately 30 to 50 million psi so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 320° to 440° C. a gaseous atmosphere comprising approximately 2 to 10 percent by volume nitrogen dioxide and approximately 90 to 98 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 25 to 90 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 13
Dependent Claim
153 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 90 percent carbon by weight and exhibiting an average single filament Young's modulus of approximately 30 to 50 million psi so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 320° to 440° C. a gaseous atmosphere comprising approximately 2 to 10 percent by volume nitrogen dioxide and approximately 90 to 98 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 25 to 90 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 14
Dependent Claim
36 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification contains at least 95 percent carbon by weight.
Claim 15
Dependent Claim
35 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification includes a substantial quantity of graphitic carbon.
Claim 16
Dependent Claim
62 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification is derived from an acrylic fibrous material selected from the group consisting of an acrylonitrile homopolymer and acrylonitrile copolymers which contain at least 85 mole percent of one or more monovinyl units copolymerized therewith.
Claim 17
Dependent Claim
31 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material is derived from a pitch fibrous material.
Claim 18
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament yarn.
Claim 19
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament tow.
Claim 20
Dependent Claim
46 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said gaseous atmosphere which is fed to said surface treatment zone comprises approximately 4 percent by volume nitrogen dioxide, and approximately 96 percent by volume air.
Claim 21
Dependent Claim
53 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 11 wherein said carbonaceous fibrous material which undergoes surface modification exhibits an average single filament tensile strength of at least 200,000 psi prior to said surface average single filament tensile strength following said surface modification.
Claim 22
Dependent Claim
159 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 95 percent carbon by weight and a substantial quantity of graphitic carbon and exhibiting an average single filament Young's modulus of at least 60 million psi so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 450° to 800° C. a gaseous atmosphere comprising approximately 2 to 10 percent by volume nitrogen dioxide and approximately 90 to 98 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 25 to 90 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 23
Dependent Claim
159 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material containing at least 95 percent carbon by weight and a substantial quantity of graphitic carbon and exhibiting an average single filament Young's modulus of at least 60 million psi so as to improve its ability to bond to a resinous matrix material while retaining a substantial portion of the tensile strength thereof comprising: (a) continuously feeding to a substantially enclosed surface treatment zone maintained at a temperature of approximately 450° to 800° C. a gaseous atmosphere comprising approximately 2 to 10 percent by volume nitrogen dioxide and approximately 90 to 98 percent by volume air, (b) continuously passing a continuous length of said carbonaceous fibrous material in the direction of its length through said surface treatment zone for a residence time of approximately 25 to 90 seconds, and (c) continuously withdrawing the resulting continuous length of carbonaceous fibrous material from said surface treatment zone.
Claim 24
Dependent Claim
36 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material which undergoes surface modification contains at least 99 percent carbon by weight.
Claim 25
Dependent Claim
71 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material which undergoes surface modification is derived from an acrylic fibrous material selected from the group consisting of an acrylonitrile homopolymer and acrylonitrile copolymers which contain at least 85 mole percent acrylonitrile units and up to about 15 mole percent of one or more monovinyl units copolymerized therewith.
Claim 26
Dependent Claim
31 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material is derived from a pitch fibrous material.
Claim 27
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament yarn.
Claim 28
Dependent Claim
33 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material which undergoes surface modification is a continuous multifilament tow.
Claim 29
Dependent Claim
46 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said gaseous atmosphere which is fed to said surface treatment zone comprises approximately 4 percent by volume nitrogen dioxide and approximately 96 percent by volume air.
Claim 30
Dependent Claim
62 words
An improved process for the modification of the surface characteristics of a carbonaceous fibrous material according to claim 20 wherein said carbonaceous fibrous material which undergoes surface modification exhibits an average single filament tensile strength of at least 200,000 psi prior to said surface modification, and retains at least 70 percent of said average single filament tensile strength following said surface modification.
References Cited (Backward Citations)
GB895990A
Cited
US3476703A
Cited
US3723607A
Cited
US3723150A
Cited
US3754957A
Cited
US3816598A
Cited
US3853610A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |