Aircraft fluid resistant sealant for use on aircraft parts
11059991 ยท 2021-07-13
Assignee
Inventors
- Jeff Busby (Millsap, TX, US)
- Mike Dry (Fort Worth, TX, US)
- Kent Boomer (Aledo, TX, US)
- Matt Boyd (Fort Worth, TX, US)
- Chad Knight (Dodd City, TX, US)
- Jeb Henderson (Fort Worth, TX, US)
- KELLY TEMPLIN (GRANBURY, TX, US)
- Peter Sibello (Fort Worth, TX, US)
Cpc classification
B64D45/00
PERFORMING OPERATIONS; TRANSPORTING
B64D2045/009
PERFORMING OPERATIONS; TRANSPORTING
B05B7/26
PERFORMING OPERATIONS; TRANSPORTING
F16J15/102
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B64F5/45
PERFORMING OPERATIONS; TRANSPORTING
B05B11/0054
PERFORMING OPERATIONS; TRANSPORTING
F16J15/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B05B7/2472
PERFORMING OPERATIONS; TRANSPORTING
B64D37/06
PERFORMING OPERATIONS; TRANSPORTING
C08G2190/00
CHEMISTRY; METALLURGY
B05B7/0408
PERFORMING OPERATIONS; TRANSPORTING
B64F5/10
PERFORMING OPERATIONS; TRANSPORTING
F16J15/104
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
B05B7/24
PERFORMING OPERATIONS; TRANSPORTING
F16J15/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B64F5/45
PERFORMING OPERATIONS; TRANSPORTING
B64D37/06
PERFORMING OPERATIONS; TRANSPORTING
B05B7/04
PERFORMING OPERATIONS; TRANSPORTING
B05B7/26
PERFORMING OPERATIONS; TRANSPORTING
F16J15/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B64D45/00
PERFORMING OPERATIONS; TRANSPORTING
B64D37/32
PERFORMING OPERATIONS; TRANSPORTING
B64F5/10
PERFORMING OPERATIONS; TRANSPORTING
B05B11/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A number of sealants are provided that are resistant to degradation by aircraft fluids. In some embodiments, the sealants are resistant to degradation by Jet A fluid and at least one of the three types of hydraulic fluids typically used in aircraft. These embodiments are also typically cure in place from a two part polyurethane or polyurea mix, with cure to a visibly clear coating. In some embodiments, they may be sprayed on an aircraft surface or applied by hand (brush or injectable). In other of these embodiments, the sealants comprise, at least in part, a cured, soft, tacky polyurethane gel that is resistant to at least one of a synthetic hydrocarbon based or mineral oil based hydraulic fluid.
Claims
1. An assembly for use with a spray gun, the spray gun for applying a sealant coating, the assembly comprising: a first compartment and a second compartment, the first compartment containing a first component, the second compartment containing a second component, the components dimensioned to engage a spray gun, and a mixing straw fluidly engaged to the first and second compartments, the mixing straw configured to receive and when the assembly is engaged with the spray gun and the spray gun is energized, combine the first and second components to form an uncured sealant mix and emit the uncured sealant mix, under pressure, from a tip of the mixing straw at a removed end thereof capable of curing to form a visibly clear, cured in place, sealant coat on an aircraft workpiece, the clear sealant coat being one of a polyurea, polyurethane or polyurea/polyurethane hybrid coat; wherein the cured sealant coat is resistant to a phosphate ester based hydraulic fluid, and also resistant to Jet A fuel; the resistance to the phosphate ester based hydraulic fluid demonstrated by a weight change of 1.66% or less (24-hour spray) and the resistance to the Jet A fuel demonstrated by a weight change of 0.07% or less (24-hour spray).
2. The assembly of claim 1, wherein the sealant coat cures to at least 85% of final hardness in 24 hours or less at 77 and 50% relative humidity.
3. The assembly of claim 1, wherein the sealant coat has a hardness of between 20 and 80 Shore A.
4. The assembly of claim 1, wherein the cured sealant coat is removable.
5. The assembly of claim 1 wherein the cured sealant coat has a tensile strength of greater than 100 psi.
6. The assembly of claim 1 wherein the cured sealant coat has an elasticity of at least 130%.
7. The assembly of claim 1 wherein the cured sealant coat is between 3 and 60 mil thick.
8. The assembly of claim 1 wherein the cured sealant coat undergoes a tint change during curing.
9. The assembly of claim 1 wherein the cured sealant coat is 3 to 60 mil thick and removable.
10. The assembly of claim 1 wherein the cured sealant coat is 3 to 60 mil thick and has an elasticity of at least 130%.
11. The assembly of claim 1 wherein the cured sealant coat is 3 to 60 mil thick and has a tensile strength of greater than 100 psi.
12. The assembly of claim 1 wherein the sealant coat cures to at least 85% of final hardness in 24 hours or less at 77 and 50% relative humidity and the cured sealant coat is between 3 and 60 mil thick.
13. The assembly of claim 1 wherein the sealant coat cures to at least 85% of final hardness in 24 hours or less at 77 and 50% relative humidity and the sealant coat has a hardness of between 20 and 80 Shore A.
14. The assembly of claim 1 wherein the sealant coat cures to at least 85% of final hardness in 24 hours or less at 77 and 50% relative humidity, the sealant coat has a hardness of between 20 and 80 Shore A and the cured sealant coat is between 3 and 60 mil thick.
15. The assembly of claim 1 wherein the cured sealant coat passes salt fog test (ASTM B117).
16. The assembly of claim 1 wherein the cured sealant coat is flame retardant (12 second vertical burn).
17. The assembly of claim 1 wherein the sealant coat is free of VOCs (Volatile Organic Compounds).
18. The assembly of claim 1 wherein the sealant coat has a peel strength of greater than 4 piw.
19. The assembly of claim 1 wherein the sealant is visually clear when coated to thickness.
20. The assembly of claim 1 wherein the viscosity of the sealant mix, prior to gelling, is between about 700 and 1200 cps.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
DETAILED DESCRIPTION OF THE EMBODIMENTS
(17) Applicant provides a two-part, polyurethane aircraft fluid resistant sealant, such as a gasket, tape, spray sealant, or injectable sealant, used at least in part, to make a sealant on aircraft parts. Applicant's sealant may be provided, in some embodiments, by use of TS1228 (available from KBS Chemical, Dodd City, Tex.) a two-part polyurethane that, when mixed, cures to form a watertight, tough, workable, durable elastomeric seal and may be used as all or part of a sealant on an aircraft part assembly, in some embodiments, a gasket, tape, injectable, or a sprayable sealant.
(18) The TS1228 polyurethane sealant was tested in accordance with RTCA DO-160G Section 11, Fluids spray and submersion susceptibility to simulate accelerated real world application scenarios. All testing was performed at room temperature and only applicable fluids were tested (see Tables 1 and 2).
(19)
(20) Submersion testing involves placing the sealant samples in a glass basin and completely submerging them in the fluid at room temperature and ambient air pressure. The samples are removed after 24 hrs. of exposure, air dry for 24 hrs., visually inspected, examined and weighed. They are then placed back in the fluid until a total of 168 hrs. of exposure is complete, then air dried, visually inspected, examined, and weighed.
(21) TS1228 was also tested for aircraft fluid spray exposure and
(22) Applicants' SF2470 (KBS, Dodd City, Tex.) is a two-part polyurea cure in place sealant with workability, removability, toughness and durability. Where the dry to touch time of TS1228 is 15-30 min. at 77 F., SF2470 is 8-20 min. Dry through means a 6 pound thumb press and 90 turn at 77 F. does not leave a permanent impression. Dry through time for TS1228 is 3-6 hours and SF2470 is 1-2 hours.
(23) Test SpecimensBoth Spray and Submersion
(24) Material under testAv-DEC TS1228 Injectable Sealant, as cured, measuring approximately 1.81.10.9 with an embedded wire
(25) Test AssemblyBoth Spray and Submersion
(26) A length of wire sufficient to hang specimen from rack was cut, measured and the mass was recorded. The material was injected into a Peel-A-Way disposable mold (R-40). The wire was embedded into the sealant. The specimens prepared for testing were allowed to cure for a period of 24 hours and then were removed from the mold. The mass of each test assembly was measured and recorded.
(27) Applicants' cured sealants have a hardness (Shore A 50-60 in one range, Shore A 20 to 80 in another), elasticity (meaning elastomeric), moisture proof ability (observed and salt fog test), thermal range (85 F. to 275 F.) and ability to withstand thermal and pressure cycling, either as a sprayable on the surface of an aircraft part, an injectable or on a gasket between facing surfaces under compression, or tape.
(28) Applicant's sealant is also flame retardant under 14 CFR 25.853(a), Appendix F, Part 1(A)(1)(ii) (12 second vertical burn). It is amber, VOC-free, solvent-free, and visually clear in coating up to about to . Moreover, it is UV resistant, being exposed to over 5,000 hours of UV light without degradation.
(29) Applicant's aircraft fluid resistant polymer sealant has a first part, resin which may have, at about 77 F. of viscosity between 70 to 250 cps, and a second part, such as a hardener, which may have at 77 F. viscosity of about 600 to 1200 cps. The gel time of a 10 gram mass at about 77 F. is less than about 15 mins. and it reaches full cure at about 8 to 24 hours. Thus, it may be termed fast curing. It has a working life after mixing of about ten minutes or less. It has a shelf life in original packaging and use within 24 hours after opening, of about nine months. It may, in some embodiments, have a peel strength of about 4.92 lbs. per inch width (4-6 in one range and 2-10 in another range), a tensile strength (ASTMD 412) of about 260 psi (or greater than 100 psi) and, in testing as an injectable, shows no corrosion present after 3000 hrs. salt fog (ASTMB 117). Peel strength is measured on a clean, dry surface of aluminum 6061/alloy with a cured thick layer, 90 peel slow, constant speed. When used as disclosed herein, it should retain its physical and chemical properties with no or minimal loss in functional properties.
(30)
(31) Applicant's aircraft fluid resistant sealants TS1228, SF2470 or U1020/P1021 may be used to comprise any part or all of gasket body 12/14/16/18/20 and the rest of the body (if any) may be a polyurethane gel as set forth in U.S. Pat. Nos. 6,530,577 6,695,320; and 7,229,516, incorporated herein by reference. There may be no perimeter portions when the entire body is comprised of TS1228, for example.
(32) Any gasket comprising at least in part body 12 may be made according to the methods described in the foregoing patents. When perimeter parts are made from Applicant's aircraft fluid resistant sealant, they may be made according to US Publication No. 2014/0167367, incorporated herein by reference.
(33)
(34)
(35)
(36) In
(37) Although the gasket depicted in
(38)
(39)
(40) Applicant's TS1228 or SF2470 sealant, whether used as an injectable, sprayable, gasket or tape, may be used in a thickness of about 3 to 60 mil in one range or about 10 to 50 mil in another range or up to in a third range and, in these ranges, and has sufficient clarity to see cracks (for example, when used as a sprayable) in the underlying aircraft part, while still being resistant to Jet A fuel and Skydrol as set forth herein.
(41) Applicant's aircraft fluid resistant polyurethane sealant is VOC and solvent-free. It displays good cohesion, when sprayed on or applied in an uncured condition, to a metallic or non-metallic surface. It displays good cohesion to a knitted or woven mesh, metallic or non-metallic of a gasket when used as part of a gasket body. A gasket made at least in part of Applicant's aircraft fluid resistant sealant work well for corrosion resistance on an aircraft workpiece comprised of an aluminum alloy. Applicant's sealant, in an uncured but mixed condition, may have a viscosity typically between about 700 and 1200 cps, allowing it to be sprayed or injected and poured pursuant to methods found in U.S. Pat. No. 9,701,388, and the other documents incorporated herein by reference.
(42)
(43) Following the method set below, it is seen in
(44) The surfaces should be cleaned with a clean cloth moistened with a cleaning solvent, such as isopropyl alcohol. Surfaces should be free of dirt, oil, grease, and other contamination prior to boot installation, including the cable, the connector, and the backshell.
(45) The ends of molded boot 70 are labeled H (and lower) and J (upper). Slide the boot J end first over the electrical connector. Ensure that H end is facing the connector. Heat the H end of the boot with a hot air tool capable of producing sufficient heat to fully recover (shrink) the boot. The boot should be located and shrunken uniformly around the connector backshell, (leaving typically at least the lower part of the connector and the coupling ring uncovered) and only until it shrinks uniformly around the backshell. With the assembly held vertical, apply heat to the J end of the boot, moving up from H end. The molded boot may be removed by disconnecting the receptacle and plug and scoring the surface of the molded boot and concentrating the heat on the scored line. The boot should begin to separate along the line after which it can be peeled off. Injectable assembly 24 should be held firmly in place above the annulus around the cables or wires while forcing element 29 urges uncured mix 32 into the void. When cured, it will help create a moisture barrier between the regular surfaces and providing corrosion protection.
(46) A sealant is provided for gasket, tape and injectable, where hardness is not needed but tackiness is, the sealant comprising soft gel in a tape, injectable or gasket, the gel with resistance to at least one of the three types of hydraulic fluid as well as Jet A fuel. In the form of a stretchable tape as illustrated in
(47)
(48) The gel, when subject to submersion in Aeroshell 31 showed the following results: 24 hours/1.7% weight gain; 48 hours/2.9% weight gain; 72 hours/3.9% weight gain; 5 days/5.2% weight gain; 10 days/5.4% weight gain; 20 days/5.5% weight gain; and, 32 days/5.5% weight gain. A weight gain of less than 10% for 24 hour immersion of the gel may be considered hydraulic fluid resistant, synthetic hydrocarbon.
(49) Tape is typically provided in a roll and, as set forth herein, may provide some tackiness or stickiness to surface for optimal corrosion protection. It also passes 12 second vertical burn. It may be used with stringers, antennas, door shelves, access panels, windscreen installations, and other suitable locations.
(50)
(51)
(52) Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. On the contrary, various modifications of the disclosed embodiments will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications, alternatives, and equivalents that fall within the true spirit and scope of the invention.
(53) TABLE-US-00001 TABLE 1 Submersion Test Result TS1228-Care Pre-Test 24 hours 168 Hours Facture Total Sample Change Total Sample Change Total Sample Sample Fluid Type Weight (g) Weight (g) Weight (g) (%) Weight (g) Weight (g) (%) Weight (g) Weight (g) Change (%) 1 Jet A Fuel 0.1129 23.9631 23.8502 0% 24.0871 23.9742 1% 24.3557 24.2428 2% 2 Autozone Brake Fluid 0.1041 22.5095 22.4054 0% 23.2124 23.1053 3% 24.3112 24.2071 8% 3 StycrolLD-4 0.1167 21.6004 21.4837 0% 23.0662 22.9495 7% 25.7519 25.6352 19% 4 AGS Silicone Brake 0.105 22.8783 22.7693 0% 12.994 22.885 1% 23.0107 22.9017 1% Fluid 5 Royco 782 0.1184 21.5808 21.5624 0% 21.8689 21.7505 1% 21.8248 21.7054 1% 6 White Mineral OS 0.1195 23.3362 23.2367 0% 23.4525 23.333 0% 23.4303 23.3108 0% 7 Royal Purple Synthetic 0.1156 21.6241 21.5063 0% 22.7459 21.6301 1% 21.737 21.6212 1% 8 Isopropyl 0.1196 21.3139 21.6343 0% 21.585 21.8654 1% 22.3207 22.2011 2% 9 Denatuced Ethyl 0.1263 22.4003 22.274 0% 22.7273 22.601 1% 23.4813 23.365 5% 10 Sky-Kleen 0.1184 23.1272 23.0088 0% 24.3259 24.2075 3% 26.6327 26.3143 13% 11 Dynalece EG 0.1168 22.5846 22.4678 0% 22.7036 22.5868 1% 22.6371 22.5203 0% 12 Dynalece PG 0.134 22.6515 22.5173 0% 22.7645 22.6305 1% 22.7245 22.5905 0% 13 De-Icing Fluid PA 0.1219 21.1519 21.03 0% 21.2707 21.1488 1% 21.1833 21.0614 0% 14 De-Ionized Water 0.1198 22.2668 22.147 0% 22.2387 22.1189 0% 22.2398 22.12 0% 15 Mobil Aero HF 0.1264 22.235 22.1066 0% 22.3495 22.2231 1% 22.3943 22.2679 1% 16 5% NaCl Solution 0.1119 23.0594 22.5475 0% 23.0781 22.9652 0% 23.0756 22.5537 0%
(54) TABLE-US-00002 TABLE 2 % Weight % Weight % Weight Change Change Change Visual Test Fluid Class (8 hrs) (16 hrs) (24 hrs) Inspection Jet A Fuel Aviation Jet A Fuel 0.08% 0.06% 0.07% No change AutoZone Brake Non-Mineral Based 0.30% 0.47% 0.64% No change Fluid Hydraulic Fluid Skydrol LD-4 Phosphate Ester- 0.65% 1.02% 1.66% No change Based Hydraulic Fluid AGS Silicone Brake Silicone-Based 0.13% 0.12% 0.21% No change Fluid Hydraulic Fluid Royco 782 Synthetic 0.11% 0.12% 0.22% No change Hydrocarbon Based Hydraulic Fluid Mobil Aero HF Mineral-Based 0.16% 0.20% 0.17% No change Hydraulic Fluid White Mineral Oil Mineral-Based 0.23% 0.09% 0.18% No change Lubricating Oil Royal Purple Ester-Based 0.19% 0.15% 0.14% No change Synthetic Lubricating Oil Isopropyl Alcohol Isopropyl Alcohol 0.08% 0.06% 0.13% No change Solvent Denatured Ethyl Denature Alcohol 0.03% 0.03% 0.06% No change Solvent Sky-Kleen Solvent N/A 0.17% 0.24% 0.52% No change Dynalene EG Ethylene Glycol De- 0.24% 0.15% 0.18% No change Icing Fluid Dynalene PG Propylene Glycol 0.22% 0.15% 0.25% No change De-Icing Fluid De-Icing Fluid N/A 0.61% 1.05% 1.12% Salt Deposits Potassium Acetate on sample De-Icing Fluid N/A 0.34% 0.31% 0.18% No change Potassium Formate De-Ionized Natural Fluid 0.07% 0.04% 0.05% No change Water