US4193829A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of low density bis-maleimide-carbon microballoon composites
Assignee: National Aeronautics and Space Administration
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Filing: 1978-06-30
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Granted: 1980-03-18
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Expires: 1998-06-30
Abstract
Abstract A process for the preparation of composite laminate structures of glass cloth preimpregnated with polybismaleimide resin and adhered to a polybismaleimide-glass or aromatic polyamide paper honeycomb cell structure filled or partially filled with a syntactic foam consisting of a mixture of bismaleimide resin and carbon microballoons. The carbon microballoons are prepared by pyrolyzing phenolic microballoons and subsequently bonded using a 2% bismaleimide solution. The laminate structures are cured for two hours at 477 DEG K. and are adhered to the honeycomb bismaleimide adhesive using a pressure of 700 kN/m2 pressure at 450 DEG K. The laminate composite is then post-cured for two hours at 527 DEG K. to produce a composite laminate having a density in the range from about 95 kilograms per cubic meter to 130 kilograms per cubic meter.
Inventors
- 👤 Demetrius A. Kourtides
- 👤 John A. Parker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:33
CPC Classifications
B; B32; B32B; B32B3/00; B32B3/10; B32B3/12; B29; B29D; B29D24/00; B29D24/002; B29D24/005; B32B37/00; B32B37/12; C; C08; C08J; C08J9/00; C08J9/32; B32B37/1207; B32B2037/1215; B32B38/00; B32B2038/0052; B32B2038/0076; B32B2260/00; B32B2260/02; B32B2260/021; B32B2260/04; B32B2260/046; C08J2379/00; C08J2379/04; C08J2379/08; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24149; Y10T428/24157; Y10T428/29; Y10T428/2982; Y10T428/30
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
59 words
A process for preparing composite structures comprising: a. impregnating a ceramic fiber cloth with a bismaleimide resin; b. curing the resin-impregnated cloth to produce a cover sheet; c. filling a polyamide paper or a bismaleimide-glass fabric honeycomb core structure with carbon microballoons; and d. bonding said cover sheet to said honeycomb core structure with a bismaleimide hot melt adhesive.
Claim 2
Dependent Claim
59 words
A process for preparing composite structures comprising: a. impregnating a ceramic fiber cloth with a bismaleimide resin; b. curing the resin-impregnated cloth to produce a cover sheet; c. filling a polyamide paper or a bismaleimide-glass fabric honeycomb core structure with carbon microballoons; and d. bonding said cover sheet to said honeycomb core structure with a bismaleimide hot melt adhesive.
Claim 3
Dependent Claim
24 words
A process in accordance with claim 1 wherein the impregnation is carried out with a solution of bismaleimide resin powder in an n-methyl-1-pyrrolidone solvent.
Claim 4
Dependent Claim
32 words
A process in accordance with claim 2 wherein said resin impregnation is accomplished by passing the cloth through a bismaleimide solution and then through a roller and wiper to assist resin impregnation.
Claim 5
Dependent Claim
24 words
A process in accordance with claim 1 additionally comprising drying said resin impregnated cloth before curing by heating for 15 minutes at 355° K.
Claim 6
Dependent Claim
41 words
A process in accordance with claim 1 wherein said curing is accomplished by a vacuum bag technique wherein said resin impregnated cloth is cured at an external pressure of about 345 kN/m 2 at about 450° K. for about 1 hour.
Claim 7
Dependent Claim
36 words
A process in accordance with claim 1 wherein said curing is accomplished by press curing between plates treated with a mold release agent at about 345 kN/m 2 at about 450° K. for about 1 hour.
Claim 8
Dependent Claim
112 words
A process for preparing composite honeycomb structures in accordance with claim 1 wherein: a. the impregnating step comprises impregnating a glass fiber cloth with a bismaleimide resin and then curing the impregnated cloth, to produce a cover sheet containing from about 30% to about 34% of the cured resin by weight; b. the filling step comprises filling a polyamide paper or bismaleimide-glass fiber cloth honeycomb core structure with carbon microballoons; and c. there is an added step of coating the microballoons in situ in the core with a bismaleimide resin in sufficient quantity to bond the microballoons to each other and to the core upon curing the resin, and curing the resin.
Claim 9
Dependent Claim
21 words
A process in accordance with claim 1 further comprising preparing the microballoons by pyrolyzing phenolic microballoons in the presence of nitrogen.
Claim 10
Dependent Claim
24 words
A process in accordance with claim 1 wherein said honeycomb core is filled by vacuum screening an isopropanol-carbon microballoon slurry into said honeycomb core.
Claim 11
Dependent Claim
18 words
A process in accordance with claim 1 further comprising soaking the microballoon-filled core with a bismaleimide resin solution.
Claim 12
Dependent Claim
22 words
A process in accordance with claim 10 comprising soaking the microballoons with a 2 percent by weight bismaleimide resin solution in n-methyl-1-pyrrolidone.
Claim 13
Dependent Claim
32 words
A process in accordance with claim 10 further comprising curing said microballoon-filled core by heating for about 2 hours at about 366° K. and for about 1 hour at about 477° K.
Claim 14
Dependent Claim
32 words
A process in accordance with claim 10 wherein said bonding is achieved in a press operated at about 477° K. and cured for about 2 hours at about 700 kN/m 3 .
Claim 15
Dependent Claim
28 words
A process in accordance with claim 1 further comprising a postcure for about 24 hours at about 477° K. to remove volatiles and to achieve minimal smoke characteristics.
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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) | 1983-03-18 | 1983-09-17 | 1984-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-18 | 1987-09-17 | 1988-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-18 | 1991-09-17 | 1992-03-18 | $7700.00 | Window Closed / Lapsed |