US4394467A
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US
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Sized carbon fibers capable of use with polyimide matrix
Assignee: SUBJECT TO AGREEMENT RECITED SEE DOCUMENT FOR DETAILS
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Filing: 1981-06-22
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Granted: 1983-07-19
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Expires: 2001-06-22
Abstract
Abstract Carbon fibers are provided which bear an improved finish coating upon the surface which is capable of withstanding the high temperatures (e.g., above 500° F.) commonly encountered during the formation of composite structures employing a polyimide matrix. The sized carbon fibers prior to the curing to form a rigid polyimide coating are flexible, may be readily handled without significant damage, and are amenable to good impregnation with the matrix resin thereby facilitating the formation of quality composite structures. The finish comprises a mixture of selected precursors for the formation of a rigid polyimide (as described). More specifically, the size composition is formed from at least one aromatic diamine, at least one aromatic dianhydride, and at least one aromatic tetracarboxylic acid diester. A film-forming polyamic acid oligomer readily forms and is present as an intermediate reaction product within the finish coating and the aromatic tetracarboxylic acid diester has been found to beneficially serve primarily as a flexibility preserving diluent during the early stages of the polyimide-forming reaction which takes place within the finish coating. The finish is fully compatible with a polyimide matrix.
Inventors
- 👤 Robert Edelman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:27
CPC Classifications
D; D01; D01F; D01F11/00; D01F11/10; D01F11/14; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2913; Y10T428/2918; Y10T428/2933; Y10T428/2938; Y10T428/31504; Y10T428/31721
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
103 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fiber of a sizing composition which comprises a polyamic acid oligomer, and is capable of yielding a rigid polyimide at elevated temperatures which is derived from the reaction of at least one aromatic diamine, at least one aromatic dianhydride, and at least one aromatic tetracarboxylic acid diester in which the carboxylic acid groups and ester groups are ortho disposed, wherein said polyamic acid oligomer is an intermediate in the formation of said rigid polyimide.
Claim 2
Dependent Claim
103 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fiber of a sizing composition which comprises a polyamic acid oligomer, and is capable of yielding a rigid polyimide at elevated temperatures which is derived from the reaction of at least one aromatic diamine, at least one aromatic dianhydride, and at least one aromatic tetracarboxylic acid diester in which the carboxylic acid groups and ester groups are ortho disposed, wherein said polyamic acid oligomer is an intermediate in the formation of said rigid polyimide.
Claim 3
Dependent Claim
39 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 wherein said coating is present in a concentration of approximately 0.5 to 1.3 percent by weight based upon the weight of the carbon fiber.
Claim 4
Dependent Claim
78 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 which is capable of forming said rigid polyimide through the reaction of approximately 50 mole percent of said at least one aromatic diamine, approximately 30 to 40 mole percent of said at least one aromatic dianhydride, and approximately 10 to 20 mole percent of said at least one aromatic tetracarboxylic acid diester wherein the carboxylic acid groups and ester groups are ortho disposed.
Claim 5
Dependent Claim
40 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 wherein acid aromatic diamine is selected from the group consisting of p-phenylenediamine, m-phenylenediamine, 4,4'-oxydianiline, 4,4'-methylenedianiline, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzophenone, 4,4'-diaminobiphenyl, 3,3'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and mixtures of the foregoing.
Claim 6
Dependent Claim
37 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 wherein said aromatic diamine is a mixture of approximately 95 percent by weight p-phenylenediamine and approximately 5 percent by weight of m-phenylenediamine.
Claim 7
Dependent Claim
31 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 wherein said aromatic dianhydride is 3,3',4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)bis(phthalic anhydride), and mixtures of the foregoing.
Claim 8
Dependent Claim
22 words
A carbon fiber having a flexible coating on the surface thereof according to claim 1 wherein said aromatic dianhydride is 3,3',4,4'-benzophenonetetracarboxylic dianhydride.
Claim 9
Dependent Claim
38 words
A carbon fiber having a coating on the surface thereof according to claim 1 wherein said aromatic tetracarboxylic acid diester is formed by the reaction of an aromatic dianhydride and an alcohol having one to six carbon atoms.
Claim 10
Dependent Claim
20 words
A carbon fiber having a flexible coating on the surface thereof according to claim 8 wherein said alcohol is ethanol.
Claim 11
Dependent Claim
41 words
A carbon fiber having a coating on the surface thereof according to claim 1 wherein said aromatic tetracarboxylic acid diester is the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid, the 3,3'-diethylester of 3,3'4,4'-(hexafluoroisopropylidene)bis(phthalic acid), the 1,5-diethylester of pyromelletic acid, and mixtures of the foregoing.
Claim 12
Dependent Claim
26 words
A carbon fiber having a coating on the surface thereof according to claim 1 wherein said aromatic tetracarboxylic acid diester is the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid.
Claim 13
Dependent Claim
103 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fiber of a sizing composition which comprises a polyamic acid oligomer, and is capable of yielding a rigid polyimide at elevated temperatures which is derived from the reaction of approximately 47.5 mole percent of p-phenylenediamine, approximately 2.5 mole percent of m-phenylenediamine, approximately 35 mole percent of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and approximately 15 mole percent of the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid wherein said polyamic acid oligomer is an intermediate in the formation of said rigid polyimide.
Claim 14
Dependent Claim
103 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fiber of a sizing composition which comprises a polyamic acid oligomer, and is capable of yielding a rigid polyimide at elevated temperatures which is derived from the reaction of approximately 47.5 mole percent of p-phenylenediamine, approximately 2.5 mole percent of m-phenylenediamine, approximately 35 mole percent of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and approximately 15 mole percent of the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid wherein said polyamic acid oligomer is an intermediate in the formation of said rigid polyimide.
Claim 15
Dependent Claim
30 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.5 to 1.3 percent by weight based upon the weight of the carbon fiber.
Claim 16
Dependent Claim
30 words
A carbon fiber having a flexible coating on the surface thereof in a concentration of approximately 0.5 to 1.3 percent by weight based upon the weight of the carbon fiber.
Claim 17
Dependent Claim
128 words
A composite structure comprising a rigid polyimide matrix having carbon fibers incorporated therein which are coated on the surface thereof with approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fibers of a sizing composition comprising a rigid polyimide coating which is derived from the reaction of at least one aromatic diamine, at least one aromatic dianhydride, and at least one aromatic tetracarboxylic acid diester in which the carboxylic acid groups and ester groups are ortho disposed, wherein a polyamic acid oligomer is formed as an intermediate during the formation of said rigid polyimide coating and is present within a flexible coating comprising said reactants which facilitates impregnation of said coated carbon fibers with said matrix during the formation of said composite structure.
Claim 18
Dependent Claim
128 words
A composite structure comprising a rigid polyimide matrix having carbon fibers incorporated therein which are coated on the surface thereof with approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fibers of a sizing composition comprising a rigid polyimide coating which is derived from the reaction of at least one aromatic diamine, at least one aromatic dianhydride, and at least one aromatic tetracarboxylic acid diester in which the carboxylic acid groups and ester groups are ortho disposed, wherein a polyamic acid oligomer is formed as an intermediate during the formation of said rigid polyimide coating and is present within a flexible coating comprising said reactants which facilitates impregnation of said coated carbon fibers with said matrix during the formation of said composite structure.
Claim 19
Dependent Claim
33 words
A composite structure according to claim 14 wherein said rigid polyimide coating is present in a concentration of approximately 0.5 to 1.3 percent by weight based upon the weight of the carbon fibers.
Claim 20
Dependent Claim
69 words
A composite structure according to claim 14 wherein said rigid polyimide coating is derived from the reaction of approximately 50 mole percent of said at least one aromatic diamine, approximately 30 to 40 mole percent of said at least one aromatic dianhydride, and approximately 10 to 20 mole percent of said at least one aromatic tetracarboxylic acid diester wherein the carboxylic acid groups and ester groups are ortho disposed.
Claim 21
Dependent Claim
32 words
A composite structure according to claim 14 wherein said aromatic diamine is selected from the group consisting of p-phenylenediamine, m-phenylenediamine, 4,4'-oxydianiline, 4-4'-methylenedianiline, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzophenone, 4,4'-diaminobiphenyl, 3,3'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and mixtures of the foregoing.
Claim 22
Dependent Claim
29 words
A composite structure according to claim 14 wherein said aromatic diamine is a mixture of approximately 95 percent by weight p-phenylenediamine and approximately 5 percent by weight of m-phenylenediamine.
Claim 23
Dependent Claim
23 words
A composite structure according to claim 14 wherein said aromatic dianhydride is 3,3',4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)bis(phthalic anhydride), and mixtures of the foregoing.
Claim 24
Dependent Claim
14 words
A composite structure according to claim 14 wherein said aromatic dianhydride is 3,3'4,4'-benzophenonetetracarboxylic dianhydride.
Claim 25
Dependent Claim
31 words
A composite structure according to claim 14 wherein said aromatic tetracarboxylic acid diester is formed by the reaction of an aromatic dianhydride and an alcohol having one to six carbon atoms.
Claim 26
Dependent Claim
12 words
A composite structure according to claim 21 wherein said alcohol is ethanol.
Claim 27
Dependent Claim
34 words
A composite structure according to claim 14 wherein said aromatic tetracarboxylic acid diester is the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid, the 3,3'-diethylester of 3,3',4,4'-(hexafluoroisopropylidene)bis(phthalic acid), the 1,5-diethylester of pyromellitic acid, and mixtures of the foregoing.
Claim 28
Dependent Claim
19 words
A composite structure according to claim 14 wherein said aromatic tetracarboxylic acid diester is the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid.
Claim 29
Dependent Claim
128 words
A composite structure comprising a rigid polyimide matrix having carbon fibers incorporated therein which are coated on the surface thereof with approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fibers of a sizing composition comprising a rigid polyimide coating which is derived from the reaction of approximately 47.5 mole percent of p-phenylenediamine, approximately 2.5 mole percent of m-phenylenediamine, approximately 35 mole percent of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and approximately 15 mole percent of the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid, wherein a polyamic acid oligomer is formed as an intermediate during the formation of said rigid polyimide coating and is present within a flexible coating comprising said reactants which facilitates impregnation of said coated carbon fibers with said matrix during the formation of said composite structure.
Claim 30
Dependent Claim
128 words
A composite structure comprising a rigid polyimide matrix having carbon fibers incorporated therein which are coated on the surface thereof with approximately 0.3 to 5.0 percent by weight based upon the weight of the carbon fibers of a sizing composition comprising a rigid polyimide coating which is derived from the reaction of approximately 47.5 mole percent of p-phenylenediamine, approximately 2.5 mole percent of m-phenylenediamine, approximately 35 mole percent of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and approximately 15 mole percent of the 3,3'-diethylester of 3,3',4,4'-benzophenonetetracarboxylic acid, wherein a polyamic acid oligomer is formed as an intermediate during the formation of said rigid polyimide coating and is present within a flexible coating comprising said reactants which facilitates impregnation of said coated carbon fibers with said matrix during the formation of said composite structure.
Claim 31
Dependent Claim
40 words
A composite structure according to claim 25 wherein said carbon fibers are coated on the surface thereof with approximately 0.5 to 1.3 percent weight based upon the weight of the carbon fibers of said sizing composition comprising a rigid polyimide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-18 | 1987-01-17 | 1987-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-18 | 1991-01-17 | 1991-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-18 | 1995-01-17 | 1995-07-19 | $7700.00 | Window Closed / Lapsed |