US4016022A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low flow, vacuum bag curable prepreg material for high performance composite systems
Assignee: United States Department of the Air Force
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Filing: 1975-12-30
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Granted: 1977-04-05
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Expires: 1995-12-30
Abstract
Abstract A composite prepreg material comprising a carboxy-terminated polybutadiene, an epoxy novolak resin, a carboxylic acid accelerator and an epoxy catalyst. When reinforced with well known reinforcing fibers or filaments, the material is eminently suitable for use in the fabrication of structural composites.
Inventors
- 👤 Charles E. Browning
- 👤 Theodore J. Reinhart, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:52
CPC Classifications
B; B32; B32B; B32B5/00; B32B5/22; B32B5/24; B32B5/26; B29; B29C; B29C70/00; B29C70/04; B29C70/06; B29C70/10; B29C70/12; B32B3/00; B32B3/10; B32B3/12; B32B5/28; C; C08; C08J; C08J5/00; C08J5/24; C08J5/241; C08J5/243; C08K; C08K5/00; C08K5/0008; C08K5/0025; C08K5/04; C08K5/09; C08K7/00; C08K7/02; C08K7/04; C08K7/06; C08L; C08L13/00; C08L63/00; C08L63/04; B29K; B29K2105/00; B29K2105/06; B29K2105/12; B29K2105/128; B32B2255/00; B32B2255/02; B32B2260/00; B32B2260/02; B32B2260/021; B32B2260/04; B32B2260/046; B32B2262/00; B32B2262/10; B32B2262/106; B32B2305/00; B32B2305/07; B32B2305/076; B32B2607/00; Y; Y10; Y10S; Y10S525/00; Y10S525/911; Y10T; Y10T428/00; Y10T428/24; Y10T428/24149; Y10T428/29; Y10T428/2913; Y10T428/2918; Y10T428/30; Y10T428/31504; Y10T428/31511; Y10T428/31529
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
306 words
A method for fabricating a composite panel which comprises the following steps: a. mixing in a common solvent 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin with 2.5 to 2.6 parts by weight of chromium octoate; b. refluxing the resulting solution for a period of about 0.25 to 3 hours; c. at the end of the reflux period, cooling the solution to room temperature; d. adding to the cooled solution 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 1 to 5 parts by weight of benzyldimethylamine; e. stirring the solution containing the added materials, thereby obtaining a resin solution; f. coating the resin solution on a tape formed of reinforcing fibers; g. evaporating solvent from the resin solution, thereby obtaining tape impregnated with the resin; h. cutting the resin impregnated tape into plies of a desired size; i. stacking the plies to a desired thickness; j. placing a porous glass reinforced Teflon coated fabric on the top and bottom of the stack of plies; k. laying a breather cloth above and below the Teflon coated fabric; l. positioning the resulting assembly on a base plate and installing a vacuum bag thereover sealed to the base plate; m. evacuating air from the bag down to about 28 to 30 inches of mercury; n. placing the assembly in an air circulating oven; o. raising the temperature in the oven from room temperature to about 325° to 375° F at a rate of 3° to 7° F per minute; and p. maintaining the assembly at a temperature in the aforementioned range for a period of 0.75 to 1.5 hours, thereby obtaining a cured composite panel, the amount of resin in the panel being substantially equal to the amount of resin in the stacked plies.
Claim 2
Independent Claim
306 words
A method for fabricating a composite panel which comprises the following steps: a. mixing in a common solvent 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin with 2.5 to 2.6 parts by weight of chromium octoate; b. refluxing the resulting solution for a period of about 0.25 to 3 hours; c. at the end of the reflux period, cooling the solution to room temperature; d. adding to the cooled solution 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 1 to 5 parts by weight of benzyldimethylamine; e. stirring the solution containing the added materials, thereby obtaining a resin solution; f. coating the resin solution on a tape formed of reinforcing fibers; g. evaporating solvent from the resin solution, thereby obtaining tape impregnated with the resin; h. cutting the resin impregnated tape into plies of a desired size; i. stacking the plies to a desired thickness; j. placing a porous glass reinforced Teflon coated fabric on the top and bottom of the stack of plies; k. laying a breather cloth above and below the Teflon coated fabric; l. positioning the resulting assembly on a base plate and installing a vacuum bag thereover sealed to the base plate; m. evacuating air from the bag down to about 28 to 30 inches of mercury; n. placing the assembly in an air circulating oven; o. raising the temperature in the oven from room temperature to about 325° to 375° F at a rate of 3° to 7° F per minute; and p. maintaining the assembly at a temperature in the aforementioned range for a period of 0.75 to 1.5 hours, thereby obtaining a cured composite panel, the amount of resin in the panel being substantially equal to the amount of resin in the stacked plies.
Claim 3
Dependent Claim
41 words
The method according to claim 1 in which the cured composite panel after removal from the vacuum bag is postcured in an air circulating oven for about 12 to 18 hours at a temperature ranging from about 375° to 425° F.
Claim 4
Dependent Claim
98 words
The method according to claim 1 in which a stack of the plies is placed on the bottom and top of a honeycomb core; the porous glass reinforced Teflon coated fabric is placed on the stacks of plies; the breather cloth is laid above and below the Teflon coated fabric; the resulting assembly is placed on the base plate having installed thereover the vacuum bag sealed to the base plate; and a cocured honeycomb sandwich panel is obtained, the amount of resin in the panel being substantially equal to the amount of resin in the stacks of plies.
Claim 5
Dependent Claim
42 words
The method according to claim 2 in which the cocured honeycomb sandwich panel after removal from the vacuum bag is postcured in an air circulating oven for about 12 to 18 hours at a temperature ranging from about 375° to 425° F.
Claim 6
Dependent Claim
80 words
A prepreg material consisting essentially of the following components: a. the reaction product obtained by reaction 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin in the presence of 2.5 to 2.6 parts by weight of chromium octoate; b. zero to 20 parts by weight of bis(4-maleimidophenyl)methane; c. 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; and d. 1 to 5 parts by weight of epoxy catalyst.
Claim 7
Dependent Claim
80 words
A prepreg material consisting essentially of the following components: a. the reaction product obtained by reaction 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin in the presence of 2.5 to 2.6 parts by weight of chromium octoate; b. zero to 20 parts by weight of bis(4-maleimidophenyl)methane; c. 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; and d. 1 to 5 parts by weight of epoxy catalyst.
Claim 8
Dependent Claim
25 words
The prepreg material according to claim 5 in which the carboxy terminated vinyl polybutadiene has a 1,2 vinyl content of about 80 to 90 percent.
Claim 9
Dependent Claim
32 words
The prepreg material according to claim 6 in which the epoxy novolak resin is an epoxy cresol novolak resin or an epoxy phenol novolak resin having a functionality of 3.8 to 5.1.
Claim 10
Dependent Claim
16 words
The prepreg material according to claim 7 in which the epoxy catalyst is an aromatic amine.
Claim 11
Dependent Claim
14 words
The prepreg material according to claim 8 in which the aromatic amine is benzyldimethylamine.
Claim 12
Independent Claim
134 words
A method for preparing a prepreg material which comprises the following steps: a. mixing in a common solvent 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin with 2.5 to 2.6 parts by weight of chromium octoate; b. refluxing the resulting solution for a period of about 0.25 to 3 hours; c. at the end of the reflux period, cooling the solution to room temperature; d. adding to the cooled solution 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 1 to 5 parts by weight of benzyldimethylamine; and e. stirring the solution containing the added materials, thereby obtaining a homogeneous solution of a prepreg material consisting essentially of a high vinyl polybutadiene endcapped with epoxy novolak resin, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and benzyldimethylamine.
Claim 13
Independent Claim
134 words
A method for preparing a prepreg material which comprises the following steps: a. mixing in a common solvent 100 parts by weight of a carboxy terminated vinyl polybutadiene and 100 to 150 parts by weight of an epoxy novolak resin with 2.5 to 2.6 parts by weight of chromium octoate; b. refluxing the resulting solution for a period of about 0.25 to 3 hours; c. at the end of the reflux period, cooling the solution to room temperature; d. adding to the cooled solution 8 to 10 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 1 to 5 parts by weight of benzyldimethylamine; and e. stirring the solution containing the added materials, thereby obtaining a homogeneous solution of a prepreg material consisting essentially of a high vinyl polybutadiene endcapped with epoxy novolak resin, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and benzyldimethylamine.
Claim 14
Dependent Claim
48 words
The method according to claim 10 in which the carboxy terminated vinyl polybutadiene has a 1,2 vinyl content of about 80 to 90 percent and the epoxy novolak resin is an epoxy cresol novolak resin or an epoxy phenol novolak resin having a functionality of 3.8 to 5.1.
Claim 15
Dependent Claim
25 words
The method according to claim 11 in which the common solvent in acetone and the solution is refluxed at a temperature of about 136° F.
Claim 16
Dependent Claim
25 words
The method according to claim 11 in which the common solvent is 2-butanone and the solution is refluxed at a temperature of about 176° F.
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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) | 1980-04-04 | 1980-10-04 | 1981-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-04 | 1984-10-04 | 1985-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-04 | 1988-10-04 | 1989-04-05 | $7700.00 | Window Closed / Lapsed |