US4353769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radar transparent rigid polyurethane laminate systems for radomes
Assignee: Individual
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Filing: 1980-10-03
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Granted: 1982-10-12
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Expires: 2000-10-03
Abstract
Abstract A polyurethane-quartz laminate suitable for aircraft radomes. Controlled amounts of a mixture of unpolymerized 4,4 diphenyl methane diisocyanate (MDI) and 2,4 toluene diisocyanate (TDI) are polymerized with ethylene glycol at a preselected temperatures and periods to produce a polymeric resin of relatively few nonpolar isocyanate groups. The resin is impregnated and cured in layers of quartz cloth to form a relatively high strength composite or laminate having a low dielectric constant.
Inventors
- 👤 Henry J. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:34
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/12; C; C08; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/30; C08G18/32; C08G18/3203; C08G18/70; C08G18/72; C08G18/74; C08G18/76; C08G18/7607; C08J; C08J5/00; C08J5/04; C08J5/0405; H; H01; H01Q; H01Q1/00; H01Q1/42; H01Q1/422; B32B2375/00; B32B2605/00; B32B2605/18; C08J2375/00; C08J2375/04; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1089; Y10T156/1092; Y10T428/00; Y10T428/31504; Y10T428/31551; Y10T428/31598; Y10T428/31601; Y10T442/00; Y10T442/20; Y10T442/2926; Y10T442/2992
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
143 words
A method of fabricating a composite laminate with low dielectric constant and low loss tangent particularly useful in radomes, comprising: heating a selected amount of 4,4-diphenyl methane diisocyanate to melt without polymerization; mixing an effective amount of 2,4-toluene diisocyanate to form a mixture of selectively reactive diisocyanates; adding to said mixture an effective amount of ethylene glycol to form a polymerized reaction product having an excess of isocyanate groups without cross-linking; heating the reaction product for a controlled time and at a controlled temperature to increase the polymerization to form a polyurethane resin of proper viscosity for optimum wetting without cross-linking; impregnating an effective amount of the resin in a plurality of plies of fibrous cloth to form a composite; and curing the composite under a controlled temperature and pressure for a predetermined time to produce a rigid polyurethane laminate by allophanate formation.
Claim 2
Independent Claim
143 words
A method of fabricating a composite laminate with low dielectric constant and low loss tangent particularly useful in radomes, comprising: heating a selected amount of 4,4-diphenyl methane diisocyanate to melt without polymerization; mixing an effective amount of 2,4-toluene diisocyanate to form a mixture of selectively reactive diisocyanates; adding to said mixture an effective amount of ethylene glycol to form a polymerized reaction product having an excess of isocyanate groups without cross-linking; heating the reaction product for a controlled time and at a controlled temperature to increase the polymerization to form a polyurethane resin of proper viscosity for optimum wetting without cross-linking; impregnating an effective amount of the resin in a plurality of plies of fibrous cloth to form a composite; and curing the composite under a controlled temperature and pressure for a predetermined time to produce a rigid polyurethane laminate by allophanate formation.
Claim 3
Dependent Claim
38 words
A method according to claim 1 wherein: 54.98 to 55.35 mole-percent 2,4-toluene diisocyanate is mixed with 20.08 to 19.93 mole percent 4,4'-diphenyl methane diisocyanate, respectively; and 24.94 to 24.72 mole-percent ethylene glycol, respectively, is added to said mixture.
Claim 4
Dependent Claim
25 words
A method according to claim 2 wherein: the ethylene glycol is added at a controlled rate so the reaction temperature does not exceed 80° C.
Claim 5
Dependent Claim
22 words
A method according to claim 3 wherein the reaction product is maintained at 102° to 110° C. for 10 to 17 hours.
Claim 6
Dependent Claim
17 words
A method according to claim 4 wherein the composite includes 33.0 to 36.3 percent by weight resin.
Claim 7
Dependent Claim
12 words
A method according to claim 5 wherein the fibrous cloth is quartz.
Claim 8
Dependent Claim
25 words
A method according to claim 6 wherein the composite is cured at approximately 149° C. and 17 to 18 psi for 4 to 6 hours.
Claim 9
Dependent Claim
24 words
A method according to claim 7 further comprising: post curing the composite in air at 157° to 162° C. for 8 to 16 hours.
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) | 1985-10-11 | 1986-04-12 | 1986-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-11 | 1990-04-12 | 1990-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-11 | 1994-04-12 | 1994-10-12 | $7700.00 | Window Closed / Lapsed |