NON-ADHESIVE THIN GEL SEALANTS AND METHODS OF MAKING AND USING THE SAME
Applicant provides a number of embodiments of a sealant, the sealant comprising a polyurethane gel which, in some embodiments, has a thickness of 12 mil or less (uncompressed). Uses of the sealant are shown, including uses between aircraft parts under compression. Sometimes the sealant may have a very thin skeleton. Sometimes the sealant is in the form of a die cut gasket, a tape or a tacky gel sprayable. Methods for making the sealant are also disclosed. The sealants may be used pre-cured or may be sprayed on to the aircraft parts and form in place.
This application claims the benefit of, priority to, and incorporates herein by reference and is a continuation in part of U.S. patent application Ser. No. 14/704,030 filed May 5, 2015 which claims the benefit of Provisional Patent Application No. 61/988,949, filed May 6, 2014; incorporated by reference US Publication No. 2003/0234498. This application incorporates by reference and claims the benefit of U.S. application Ser. No. 15/472,859, filed Mar. 29, 2017.
FIELD OF THE INVENTIONGaskets, more specifically, a thin, pre-cured gel sealing member for in one use between two parts in an aircraft, the two parts under compression, such as a lap joint on a fuselage of an aircraft, and methods for making an assembly, such as a gasket and lap joint.
BACKGROUND OF THE INVENTIONA number of problems may be encountered with sealants. They must be dimensionally appropriate; they must provide an effective environmental seal; they must be adapted to receive rivets or other fasteners; they must maintain resiliency and avoid excessive creep under load; they must be able to withstand repeated thermal and pressure cycling; and they must be cost effective taking into account labor, manufacturing, installation, and in-service. Thus, typically, prior art sealant materials tend to be a compromise.
Applicant has heretofore used gaskets, gasket tape, and other sealants, as well as a method for making gaskets and other sealants as found and set forth in the following issued patents that are incorporated herein by reference: U.S. Pat. Nos. 6,530,577; 6,695,320; 7,229,526; and U.S. application Ser. No. 15/472,859. These patents also show uses for tacky polyurethane gel gaskets in aircraft which are also uses for the sealants disclosed herein.
Applicant has found certain problems inherent in the manufacture and use of very thin polyurethane only (no skeleton) gaskets. Applicant's disclosures herein solve some of these problems.
SUMMARY OF THE INVENTIONResilient materials are provided for, in some embodiments, sealing complementary overlapping or closely abutting edges of aircraft on an aircraft fuselage, such as on lap joints or at other locations. Air and watertight seals are sometimes created by the use of cured in-place materials, where two parts are mixed together, then applied uncured very thinly to a sealing surface, and allowed to cure after assembly—that is to say, wet installed. In some assemblies the use of a thin, precured non-adhesive gel, such as polyurethane gel may be desirable. Applicants have found, however, that there are difficulties in handling very thin gel, in particular a gel with either no skeleton or a very thin skeleton—and less than about 12 mil thick. The gel tends to come apart very easily as it is tacky and, being thin and lacking structural integrity (no skeleton embodiments) may stick to the release paper upon which it is placed.
A thin, cured gel gasket is disclosed, including methods of making the thin gel gasket and the use of the thin gel gasket with aircraft parts, including in an aircraft lap joint. In some embodiments, the thin gel gasket has no skeleton or other structure and is comprised of only a stretchable, cured polyurethane gel and has a thickness of less than 12 mil. The gasket may be manufactured using a release film that is adapted in a number of ways to make removal from the gel prior to use easier. In certain methods of making and using this thin gel gasket, it is applied to a joint or assembly which is subject to compression, such as, for example, a lap joint of an aircraft fuselage.
A joint or assembly for use on an aircraft fuselage is also disclosed. The joint may include: a first aluminum panel (or one made of other suitable material) having an outer edge portion; a second aluminum panel having an outer edge portion; a multiplicity of rivets, each having a rivet head and rivet shaft, the rivets for joining the two panels along facing overlapping outer edge portions; a sealant between the overlapping edge portions, the sealant comprising a resilient cured polyurethane gel gasket having a tacky body. In some embodiments, the gasket has a thickness of less than 12 mil uncompressed. The gasket may have a thickness of between about 1-6 mil when compressed between the two panels or other aircraft parts.
In certain embodiments, at least some of the multiplicity of rivets may include a tacky polyurethane uncured gel mix on the shaft thereof. The gel mix may cure after a few minutes. This gel mix is uncured when first applied. The joint further may include a temporary tack decreasing agent on a surface of the gasket. The joint or assembly may, for example, be a lap joint, a double lap joint, a tapered lap joint or a snap joint.
An aircraft having a fuselage is disclosed, the fuselage comprising: multiple partially overlapping panels, the overlap comprising multiple lap joints; wherein the lap joints comprise facing surfaces with rivets, the facing surfaces with a thin, tacky, cured, deformable, resilient polyurethane preformed gasket therebetween; wherein the compressed gasket thickness is less than 6 mil.
A method of joining adjacent overlapping panels on an aircraft fuselage is disclosed, the method comprising: obtaining a thin, cured polyurethane gasket or gasket tape having a first, tacky side and release paper on a second side; applying the first, tacky side to an outer edge of one of either an inner panel or an outer panel of the overlapping panels; positioning an outer edge of the other panel of the overlapping panels adjacent the gasket or gasket tape such that an overlap width approximates a tape width; removing the release paper from the second side of the gasket or gasket tape before the following step; and joining the panels with rivets so the edges hold the gasket or gasket tape under compression.
A method of manufacturing a thin gel gasket assembly is also disclosed. The method may include: providing a release film that has been adapted to easily release from a thin gel gasket; applying an uncured mix of the gel to the adapted release film to a thickness of 12 mil or less; and allowing the gel to cure. The release film of the providing step, in certain embodiments, has multiple perforations therethrough. The release film of the providing step is, in some embodiments, at least partly coated with release agent. The release film of the providing step is, in particular embodiments, meltable.
In an effort to meet environmental sealing problems, Applicants provide, in certain embodiments, a thin, polyurethane-only (no skeleton) sealant, gasket or tape as more particularly set forth below. A method of making and using the same in a lap joint or other aircraft assembly is also provided.
In certain embodiments, there is provided a lap joint for use on an aircraft fuselage. The lap joint may include a first aluminum panel having an edge portion; a second aluminum panel having an outer edge portion; a multiplicity of rivets joining the two panels along complementary overlapping edge portions; a sealant, such as a tape, for placement between the overlapping edge portions, the sealant, in one embodiment, consisting essentially of a cured polyurethane tape gasket having a tacky upper and lower surface, the gasket having a pre-compression thickness of between 2-12 mil, more preferably, 6-8 mil, wherein the multiplicity of rivets includes an uncured polyurethane mix applied immediately upon mixing and before curing to the rivets and/or panel rivet holes, just before installation of the rivets, wherein optionally a temporary tack decreasing agent is applied to either or both of the edge portion(s) of the panels and/or the surfaces of the gasket, prior to contacting the gasket with the panel(s).
There is provided, in particular embodiments, a method of manufacturing a thin, tacky polyurethane gasket. The method may include: applying a thin film 2-12 mil thick, of an uncured polyol/isocynate mix to at least one release film that has a low bonding cohesion with respect to the polyurethane; allowing the polyurethane to cure; removing the release film; and applying the gasket to a lap joint of an aircraft.
The embodiments of the sealant disclosed is tacky, but not an adhesive. Adhesive based products and gel based sealants differ in several ways. One of them is not only what their intended use is, but also in their basic structures, bonding, and physical characteristics. Adhesives provide a more permanent, rigid and durable bond as opposed to sealants, such as gels, which are lower in strength and far more malleable. Sealants are typically not used to bond parts, such as parts under compression, permanently together. Adhesives have more power for holding and bonding, but sealants are good for air and water tight spaces and as gap fillers. Sealants have lower bonding strength and a higher elongation percentage than adhesives. Sealants are meant to provide a watertight seal, but are easily removable when necessary. Adhesives typically are not meant to be removed from the part to which they are bonded.
FIGS. 7C1, 7C2, and 7C3 all illustrate a lap patch which uses embodiments of Applicant's sealants disclosed herein.
Applicant provides, as seen in
Gasket 12, in one embodiment, has an uncompressed thickness of about 2 to 12 mil or, more preferably, about 6 to 8 mil, which thickness is the thickness as applied (see
The composition of gasket 12 may be found in the patents incorporated herein by reference and is typically pre-cured, that is, cured prior to placement between panels A and B (see
A. Methods of Making the Thin Gasket
One of the difficulties in working with a thin polyurethane gasket is in the manufacture of the gasket.
In one embodiment, a flat, level mold 18 is provided having a bottom wall and side walls 20 and an open top. The mold may be about 2′ wide and about 12′ long. A bottom film 16 (a release film designated with 16 because of its placement beneath uncured mix) of release film or non-release film is laid either across the bottom or across the bottom and at least partially up the sides of the mold. In one embodiment, a two-part polyurethane comprising a polyol 24 and an isocyanate 26 is injected into mold 18 using a mixing cartridge 22 that has a nozzle 22a for mixing the two parts. The volume of the mix injected is known and set so that it provides the selected body thickness, for example, about 6 to 8 mil or in the range of 2-12 mil. The mix will chemically react and set (cure) at ambient temperature in mold 18 on top of bottom film 16. Typically, the cure (to about 90%) of final hardness occurs in about 30 to 90 minutes. Before it sets, it, being self-leveling, the mix will be spread out or may be leveled with a handheld straight edge. Bottom film 16 is provided for the releasing, post-curing of the tacky gasket polyurethane material from the mold.
It has heretofore been difficult to remove the release films from a thin polyurethane gel gasket 12. In an effort to help achieve clean removal of the release film, several solutions are set forth below.
B. Physical Configuration or Chemical Composition of the Film
In
In
In
In some embodiments (see
C. The Use of a Release Agent Applied to the Release Film
By controlling the speed at which one moves the mixing cartridge across the film and the rate of mix application, one can, with experience, obtain a thin, relatively wide strip. A top film may be placed on it, for example, after curing. Then it may be cut in multiple strips, lengthwise, to the desired width. In either method, leveling and a selected “thinness” may be further controlled by using a rigid roller 40 having end ridges 41, such as that shown in
Certain types of release film may work by being physically altered, chemically altered or receiving a release agent on the surface thereof as set forth in
D. Joint or Other Aircraft Assemblies Using Applicant's Thin Polyurethane Gel Sealant
The compositions that may be used in this step illustrated in
Additional embodiments appropriate for receiving applicants thin skeleton less gasket conclude include double lap joints
Other non-lap joint aircraft parts or assemblies that may use the sealants disclosed herein include aircraft antennas, between floorboards and floorboard support structures, between window seat tracks and window seat floors where wing lugs join fuselage lugs, in electronic equipment bays where electronic equipment rests in racks, on a floor or shelves (where moisture can collect and cause corrosion), where dissimilar metals meet to help prevent galvanic corrosion, conductive and non-conductive thin gel washers or tapes for EME (electromagnetic environment) grounding or isolating metal or electronic elements, including conductors and/or grounds, on electrical and structural aircraft systems. Any of the sealants disclosed herein may also be used in EME areas, electronic sources and fixtures. Applicant's sealants can be used on or around radio transmitters, receivers, oscillators, motors, lamps, energy ignition relays, heaters, computers, and peripherals and the like.
FIGS. 7C1, 7C2, and 7C3 are additional drawings of an ABDR (aircraft battle damage repair) or a lap joint repair. FIG. 7C1 shows a first or outer patch and a second or inner patch (dashed lines) with the sealant between the holes shown in dashed lines. In other words, the aircraft skin in the border area adjacent the hole receives an outer patch and an inner patch (or at least one) with fasteners therethrough to reinforce the hole. Applicant's sealant may be between the outer patch and the skin border area or between the inner patch and the skin border area, but typically is between both the outer patch and the skin border area and the inner patch and the skin border area, and fasteners, such as rivets, can be used between the outer and inner patch. FIG. 7C2 shows an inside view of a patch, which in this embodiment, may be a single patch reinforcing an area around battle damage. FIG. 7C3 shows another view, close up, of FIG. 7C2, showing the gel of the deformable gel sealant oozing out between the aircraft skin and the inner patch.
Areas where Applicant's thin gel sealant may be applied, either as a cured, tacky gel gasket or spray-on cure-in-place (see below), include between the faying surfaces of the following types of joints: bonded doubler; unsupported single lap joint; single strap joint; tapered single lap joint; double lap joint; double strap joint; tapered strap joint; stepped lap joint; and scarf joint (see NIAR.wichita.edu/nairworkshops/portals/0/jun17_0345_stevew_dh.pdf, incorporated herein by reference), NSE Composites, page 4, article entitled “Composite Bonded Joints Analysis, Data and Substantiation,” Jun. 16-18, 2004, D. M. Hoyt and Steve Ward, NSE Composites, Seattle, Wash. While these show bonded joints, the use of Applicant's thin gel sealants provide for non-bonded joints that are fastener held (mechanically bonded rather than adhesively bonded), where the joints are under compression but, with Applicant's novel sealant compositions, removability is retained, though some shear strength is sacrificed. In some embodiments, Applicant's thin gel sealants are used with bolted composite structures, that is, non-adhesive joints (adhesive bond joints), Applicant's sealants provide removability and good environmental seal. Some mechanically fastened permanent or removable joints may be found in U.S. Pat. No. 7,678,437, incorporated herein by reference.
Adhesive based products and gel based sealants differ on several scales. One of them is not only what their intended use is, but also in their basic structures, bonding, and physical characteristics. Adhesives provide a more permanent, rigid and durable bonding as opposed to sealants, such as gels, which are lower in strength (including shear) and far more malleable. Sealants are typically not used to bond things permanently together. Adhesives have more power for holding and bonding, but sealants are good for air and water tight spaces and as gap fillers. Sealants have lower bonding strength and a higher elongation percentage than adhesives. Sealants are meant to provide a watertight seal, but are easily removable when necessary. Adhesives typically are not meant to be removed.
E. A Tacky Sprayable Polyurethane Cure in Place Sealant
While the embodiments set forth above illustrate a thin gel (gel only or gel with a thin skeleton), sealant or gasket, in some embodiments, with a gasket body having a release film engaged therewith, Applicant may also provide for a sprayable tacky sealant that comes in a two-part cartridge 102 for use with a pneumatic gun 104 (see WO 2017/172906 entitled “A Clear Sprayable Sealant for Aircraft Parts and Assemblies”; see also PCT/US2017/024735, incorporated herein by reference).
Although the invention has been described with reference to specific embodiments, 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.
Claims
1. A device for use on an aircraft assembly, the aircraft assembly having a first part having an inner face portion; a second part having an inner face portion; and a multiplicity of fasteners for joining the two parts, the device comprising:
- a sealant for placement between the two inner face portions, the sealant comprising a tacky, deformable body of polyurethane gel, the body with tacky outer faces wherein the body has a thickness of 12 mil or less uncompressed;
- further comprising a skeleton configured with many openings, the skeleton encapsulated in the body and the skeleton having an uncompressed thickness of 12 mil or less.
2. The device of claim 1, wherein the body has a thickness of between about 1-6 mil when compressed between the two parts.
3. The device of claim 1, wherein the polyurethane gel is cured.
4. The device of claim 1, wherein the assembly is a lap joint, a double, a patch, a heat shield or include electronic equipment.
5. The device of claim 1, wherein the tacky body is deposited on one or both of the first or second part by a pneumatic spray gel.
6. The device of claim 1, wherein the body is pre-cured before placement on one of the two inner face portions.
7. The device of claim 1, wherein the body cures after placement on one of the two inner face portions.
8. The device of claim 1, further comprising a release film.
9. The device of claim 1, wherein the skeleton is a woven mesh.
10. The device of claim 1, wherein the skeleton is metallic.
11. The device of claim 1, wherein the skeleton is non-metallic.
12. The device of claim 1, wherein the skeleton is molded or extruded polyamide or polypropylene.
13. An aircraft having a fuselage, the fuselage comprising:
- multiple panels which overlap partially, the overlaps comprising multiple lap joints; wherein the lap joints comprise facing surfaces, the facing surfaces having a thin, tacky, cured, deformable, resilient polyurethane gasket for compression therebetween.
14. The fuselage of claim 13, wherein the compressed gasket thickness is less than about 6 mil.
15. The fuselage of claim 13, wherein the gasket includes a skeleton.
16. A method of joining two adjacent parts on an aircraft, the method comprising the steps of:
- obtaining a thin gasket assembly comprising a cured polyurethane gel body gasket or tape having a first, tacky side and a second tacky side, the gasket assembly comprising a release film on one of the sides;
- applying the first side to an inner face of one of the two parts;
- positioning an inner face of the other of the two parts adjacent the gasket or tape;
- removing the release film from the second side of the gasket before the following step; and, joining the parts with fasteners.
17. A method of manufacturing a thin gasket having a tacky polyurethane gel body, the method comprising the steps of:
- providing a release film that has been to easily release from a cured tacky polyurethane gel body;
- applying an uncured mix of the gel to the adapted release film to a thickness of about 12 mil or less; and
- allowing the uncured mix to cure.
18. The method of claim 17, wherein the release film of the providing step has multiple perforations therethrough.
19. The method of claim 17, wherein the release film of the providing step is at least partly coated with release agent.
20. The method of claim 17, wherein the release film of the providing step is meltable.
21. A sealant for use with an aircraft having a first part and a second part connected with fasteners, the sealant consisting essentially of:
- a sealant for receipt between the parts of the aircraft, the sealant comprising a resilient, cured, deformable, polyurethane body having a tacky polyurethane upper surface and a tacky polyurethane lower surface; and
- at least one release film for placement against at least one of the upper or lower surfaces of the body, the release film for removal from the body before placement of the sealant on an aircraft part.
22. The sealant of claim 21, wherein the body has an uncompressed thickness of less than 12 mil.
23. The sealant of claim 21, wherein the body has an uncompressed thickness of between 2 and 12 mil.
24. The sealant of claim 21, wherein the body has a compressed thickness of between about 1-6 mil.
25. The sealant of claim 21, further including a temporary tack decreasing agent on at least one of the upper or lower surface of the body.
26. The device of claim 21, wherein the at least one release film is one release film on one of the upper or lower surface of the sealant and a second release film on the other of the upper or lower surface of the sealant.
27. The device of claim 21, wherein the release film has multiple small perforations.
28. The device of claim 21, wherein the release film is dissolvable in a liquid.
29. The device of claim 21, wherein the release film is heat meltable.
30. The device of claim 21, wherein the release film is an FEP (fluorinated ethylene propylene) sheet.
31. The device of claim 21, wherein the release film is plastic.
32. The device of claim 21, wherein an inert agent is applied to a surface of the release film which engages the sealant.
33. A method of joining with multiple fasteners, adjacent, inner and outer overlapping panels of an aircraft fuselage, the panels having fastener holes, the method comprising the steps of:
- obtaining a sealant tape comprising a thin, cured, tacky polyurethane gel body having a first, tacky polyurethane surface and a release film on a second cured tacky polyurethane surface;
- applying the first, tacky polyurethane surface of the body to an outer edge of one of either the inner panel or the outer panel of the overlapping panels;
- positioning the outer edge of the other panel of the overlapping panels adjacent the sealant tape such that an overlap width approximates a sealant tape width;
- removing the release film from the second surface of the sealant tape; and
- joining the panels with the fasteners so the edges hold the polyurethane gel body under sufficient compression to cause some deformation of the polyurethane gel.
34. The method of claim 33, further comprising the step of:
- applying an uncured mix of polyurethane gel proximate the fasteners.
35. The method of claim 33, wherein the release film of the providing step has multiple perforations therethrough.
36. The method of claim 33, wherein the release film of the providing step is at least partly coated with release agent.
37. The method of claim 33, wherein the release film of the providing step is meltable.
38. The method of claim 33, wherein the release film is plastic.
39. The method of claim 33, wherein the release film is dissolvable.
40. The method of claim 33, further including the step of, prior to the joining step, covering at least partly the first surface with a temporary tack release agent.
41. The method of claim 33, wherein the uncompressed thickness of the sealant tape is about 12 mil or less and the compressed thickness is between about 1-6 mil.
42. A device for use with an aircraft assembly having a first part and a second part, and fasteners, for applying compression to the two parts, the device comprising:
- a sealant for receipt between the parts of the aircraft, the sealant comprising a resilient, cured, deformable, skeleton-free, polyurethane body having a tacky polyurethane upper surface and a tacky polyurethane lower surface; and
- a skeleton between 1-12 mm thick, the skeleton covered and encapsulated in the polyurethane body.
Type: Application
Filed: Oct 31, 2017
Publication Date: Mar 8, 2018
Inventors: Jeff Busby (Millsap, TX), David Schmidt (Egg Harbor Township, NJ), Kent Boomer (Alvedo, TX), Matt Boyd (Fort Worth, TX), Mike Dry (Fort Worth, TX), Chad Knight (Dodd City, TX), Peter Sibello (Benbrook, TX)
Application Number: 15/799,022