Selectively compacted membrane sealant and method for its production

Abstract

Selectively compacted composite sealant (100, 400, 500, 600, 700, 900), comprising: a porous layer (102, 302, 402, 502, 602, 702, 902) with a first main surface and an opposing second main surface, wherein the porous layer (102, 302, 402, 502, 602, 702, 902) comprises a porous membrane and has alternating compacted sections (108, 306, 404, 504, 604, 704, 904) and non-compacted sections (110, 308, 406, 506, 606, 706, 906), wherein the compacted (108, 306, 404, 504, 604, 704, 904) and non-compacted (110, 308, 406, 506, 606, 706, 906) sections form respective valleys and peaks in at least one of the first and second main surfaces of the porous layer (102, 302, 402, 502, 602, 702, 902);at least one elastomeric layer (104, 106, 314, 408, 508, 608, 708, 908) arranged on one or both of the first and second main surfaces, wherein the at least one elastomeric layer (104, 106, 314, 408, 508, 608, 708, 908) comprises an elastomeric material that fills the valleys in the first and / or second main surface of the porous layer (102, 302, 402, 502, 602, 702, 902), wherein the non-compacted sections (110, 308, 406, 506, 606, 706, 906) are discontinuous and are connected by the compacted sections (108, 306, 404, 504, 604, 704, 904) are separate;and wherein the valleys formed over the compacted sections (108, 306, 404, 504, 604, 704, 904) are filled with the elastomer layer (104, 106, 314, 408, 508, 608, 708, 908) which covers the non-compacted sections (110, 308, 406, 506, 606, 706, 906) more narrowly in order to form smooth upper (416, 516, 616, 716) and lower (418, 518, 618, 718) surfaces of the composite sealant (100, 400, 500, 600, 700, 900).

Description

TECHNICAL AREA

[0001] The present disclosure relates generally to composite sealants. In particular, the disclosure relates to selectively compacted membrane composite sealants for sealing connections. BACKGROUND

[0002] Many industries use sealants to prevent the ingress of liquids between physical components in products or structures. Common sealants include paints, sealants, polymeric materials, O-rings and gaskets, and vary depending on the application. The aerospace industry, in particular, uses sealants to protect various interfaces to prevent corrosion and surface degradation, for example, due to the ingress of water or chemicals.

[0003] One of the materials commonly used by the aircraft industry is a two-part liquid polysulfide sealant used to enhance the protection of various interfaces against corrosion and surface degradation. This practice can be used to protect assemblies such as mounted brackets along the airframe. For example, a material (such as aluminum, fiber-reinforced plastic, or carbon composite) may be attached to a section of the airframe using bolts or rivets. An assembler can apply liquid sealant between the joined parts and then attach the bracket to the airframe using fasteners. When the fasteners are tightened, the pressure from the fastener heads can distribute the sealant. The sealant typically needs to be left to cure at room temperature for extended periods, such as 72 hours or more, depending on the sealant grade.This process is time-consuming, requires careful mixing and application techniques, and usually necessitates personal protective equipment (PPE) and ventilation due to the volatile organic compounds (VOCs) released during the process.

[0004] Conventional designs that use "dry seal" materials such as O-rings, flat gaskets, or other flexible structures require precise placement and pressure to be effective and are susceptible to degradation over time due to chemical attack. Dry seal materials that can withstand chemical attack often fail to function within the required temperature ranges and are frequently associated with shortcomings, particularly at low operating temperatures and with variable conformability. Liquid sealants, which more readily conform to specific interface geometries, are associated with drawbacks such as difficult installation procedures and cannot be easily removed once fitted without damaging the seal.Furthermore, polysulfide liquid sealants often become ineffective after prolonged exposure to certain harsh chemicals, such as phosphate ester hydraulic fluid. Accordingly, there is a need for sealing technologies that can operate in a variety of interface profiles without compromising durability, performance across a wide temperature range, or resistance to weathering and / or chemical attack. SHORT SYNOPSIS

[0005] The present disclosure relates to a selectively densified composite sealant. The selectively densified composite sealant includes a porous layer and at least one elastomeric layer. The porous layer has a first main surface and an opposing second main surface and includes a porous membrane. The porous layer may have alternating densified and non-densified sections. The alternating densified and non-densified sections may form respective valleys and peaks in at least one of the first main surface and / or the second main surface of the porous layer. The non-densified sections may be discontinuous and separated by the densified sections. The densified sections may be generated by increasing the density of the porous layer. However, the porous layer may not be completely densified.

[0006] At least one of the first and second main surfaces can define respective valleys and peaks of the porous layer. The other of the at least one of the first and second main surfaces can be flat or can also define respective valleys and peaks of the porous layer. In embodiments in which both the first and second main surfaces define respective valleys and peaks, the peaks of the first planar main surface can be arranged substantially over the corresponding peaks of the second planar main surface of the porous layer. Similarly, the valleys of the first planar main surface can be arranged substantially over the corresponding valleys of the second planar main surface of the porous layer.In embodiments where both the first and second main surfaces define respective valleys and peaks, the respective valleys and peaks on the first main surface can be located at different XY positions on the valleys on the second main surface. Alternatively, in embodiments where both the first and second main surfaces define peaks and valleys, the valleys of the first main surface can be located substantially over the peaks of the second main surface. The dense first sections of the porous layer can be continuous along a Z-axis (thickness axis) of the porous layer.

[0007] The at least one elastomer layer can be arranged on the first main surface. The at least one elastomer layer can comprise a first elastomer layer. The at least one elastomer layer can be formed from a first elastomer material. The at least one elastomer layer can fill the valleys of the compacted sections of the porous layer. The at least one elastomer layer can fill the valleys of the compacted sections of the first main surface of the porous layer. The composite sealant can contain a second elastomer layer arranged on the second main surface. The at least one elastomer layer can comprise a second elastomer layer. The at least one elastomer layer can be formed from a second elastomer material. The at least one elastomer layer can fill the valleys of the compacted sections of the porous layer.The at least one elastomer layer can fill the valleys of the compacted sections of the second main surface of the porous layer.

[0008] The first and second elastomer materials can be the same elastomer material, or they can be different elastomer materials. The first and / or second elastomer material can be chemically inert with respect to at least one of the possible stress fluids (e.g., water, jet fuel, common solvents such as organic solvents, de-icing fluid). The first and / or second elastomer material may not become wet when exposed to fluid. The elastomer material can be any suitable elastomer that can be formed into a complex surface (e.g., a grooved or patterned surface). The elastomer can be a polymer designed to be deposited as a liquid, i.e., cast, molded, printed, or otherwise deposited, and then cured to retain its shape. Alternatively, the elastomer can be deposited by heat treatment, e.g.,Melting and deposition onto the porous membrane. After setting and curing, the elastomer fills the valleys between uncompacted areas of the porous membrane, while the porous membrane is designed to be reversibly compressed under load to provide sealing capabilities with a high working range, i.e., capable of sealing a gap in an interface over a wide range of clamping pressures or between uneven surfaces. In embodiments, the elastomer material comprises an elastomer matrix containing one or more silicone, fluorosilicone, or perfluoropolyether elastomers. The elastomer may include a fluoroelastomer.

[0009] In embodiments where the second main surface defines valleys and peaks of the porous layer, the second elastomer layer can fill the valleys of the second main surface of the porous layer. The composite sealant can have a first elastomer layer arranged on the first main surface and a second elastomer layer arranged on the second main surface. The first and second elastomer materials can optionally be the same elastomer material.

[0010] Providing a porous material comprising compacted and non-compacted sections and at least one elastomeric layer can provide a liquid seal when compressed. The non-compacted sections of the porous material may become moistened when subjected to liquid stress (i.e., exposed to a liquid) if no elastomeric material is incorporated within it. If the porous material is substantially compacted, the substantially compacted porous material may not become moistened when subjected to liquid stress (even if no elastomeric material is incorporated within the substantially compacted porous material). The porous material may not become moistened at the compacted sections. Additionally, the at least one elastomeric layer may prevent liquid from penetrating the selectively compacted composite sealant when subjected to liquid stress.

[0011] In the Z-axis (thickness) of the selectively compacted composite sealant, the composite material comprises at least one elastomer layer and the compacted area. In some embodiments, the composite material in the Z-axis (thickness) of the selectively compacted composite sealant comprises at least two elastomer layers that sandwich the porous layer in between. Without being bound to any specific theory, the section of the composite material that comprises compacted sections of the porous layer with elastomeric material, which fills the valleys of the compacted area, represents the

[0012] Sections of the porous material are filled, and when compressed, provide protection against fluid ingress (e.g., at a coupling point). The non-compacted sections of the selectively compacted composite sealant allow the sealant to become flexible and provide a degree of compression under pressure (e.g., at a joint or coupling point). The geometry of the compacted sections, together with the non-compacted sections between them, allows the composite sealant to remain soft and flexible while providing a fluid seal under pressure.

[0013] The porous layer can be a porous polymer or fluoropolymer, such as an ePTFE (expanded polytetrafluoroethylene) membrane, a polypropylene membrane, or an ePE (expanded polyethylene) membrane. The selectively densified composite sealant can contain a porous layer comprising expanded polytetrafluoroethylene (ePTFE). The selectively densified composite sealant can contain a porous layer consisting substantially of expanded polytetrafluoroethylene (ePTFE). In embodiments containing a porous layer comprising ePTFE, the ePTFE layer can be produced according to the teachings of US 3,953,566. In embodiments containing a porous layer comprising an ePE layer, the ePE layer can be produced according to US 9,926,416.

[0014] The selectively compacted composite sealant may further include a barrier layer positioned between the porous layer and at least one of the first and / or second elastomer layers. The barrier layer may be designed to prevent the penetration of elastomeric material from the first and / or second elastomer layer into the porous layer. The barrier layer may allow partial penetration (i.e., absorption) of elastomeric material from the first and / or second elastomer layer into the porous layer. The barrier layer may completely prevent the penetration of elastomeric material from the first and / or second elastomer layer into the porous layer.The elastomeric material of the at least one elastomeric layer can partially penetrate the porous layer, particularly the uncompacted section, especially in embodiments where the selectively compacted composite sealant does not include a barrier layer. The degree of incorporation of the elastomeric material into the porous layer in embodiments that include an intermediate barrier layer can be adjusted by the type of barrier layer material, the viscosity and type of elastomer, and other processing variables of the selectively compacted composite sealant. The barrier layer can comprise any suitable non-moistenable film or membrane, such as, but not limited to, a polymer or fluoropolymer film.The barrier layer may comprise or substantially consist of a pressure-compacted ePTFE film, a non-moistenable ePTFE film, a fluorinated ethylene propylene FEP, a non-moistenable ePE film, or the like. In preferred embodiments, the barrier layer may comprise a non-moistenable ePTFE layer. In embodiments in which the selectively compacted composite sealant does not comprise a barrier layer, the elastomeric material of the at least one elastomeric layer may partially penetrate the porous layer (i.e., the elastomeric material may be at least partially incorporated into the porous layer). In embodiments in which the selectively compacted composite sealant does not comprise a barrier layer, the elastomeric material may be at least partially incorporated into the non-compacted portions of the porous layer. Optionally, the elastomeric material may be completely incorporated into the non-compacted portions of the elastomeric material.

[0015] The first elastomer material and / or the second elastomer material can be formed from a single elastomer layer or a multitude of elastomer layers (e.g. 2 layers, 3 layers, 4 layers or more).

[0016] The selectively compacted composite sealant may further comprise an adhesive in at least one of the first elastomer layer and / or the second elastomer layer.

[0017] The adhesive can be applied intermittently (e.g. as individual dots) or it can be applied as a continuous layer of adhesive.

[0018] The porous layer of the composite sealant can have compacted and non-compacted sections forming a repeating pattern. This repeating pattern can be any suitable pattern, including, but not limited to, a rectangular or square grid, parallel lines, or diamonds. The compacted and non-compacted sections can define any shape, such as dots, squares, rectangles, triangles, diamonds, ovals, curved lines (e.g., wavy lines), and the like. Generally, the non-compacted sections are separated from each other by the compacted sections along the length and width of the composite sealant.

[0019] The first and / or second main surface can define alternating densified and undensified sections, forming respective valleys and peaks in a repeating grid pattern. The first and / or second main surface can define a first set of valleys forming substantially parallel lines and a second set of valleys forming substantially parallel lines, the first set of valleys being substantially perpendicular to the second set of valleys. The surface opposite the first or second main surface can be substantially flat, or it can define a corresponding grid pattern on the opposite main surface. Optionally, the corresponding grid patterns on the first and second main surfaces can be aligned along a Z-axis (thickness axis) of the porous layer.The repeating pattern can be a grid formed by applying pressure to the first or second principal surface in a pattern of a first set of substantially parallel lines and applying pressure to the other (opposite) principal surface in a pattern of a second set of substantially parallel lines, the first set of substantially parallel lines being substantially perpendicular to the second set of substantially parallel lines. The first or second principal surface can define a first set of valleys forming substantially parallel lines, and the other of the first or second principal surface can define a second set of valleys forming substantially parallel lines, the first set of valleys being substantially perpendicular to the second set of valleys.

[0020] The repeating pattern can be formed on only one of the first or the second principal surface, or it can be formed on both the first and the second principal surface. For example, the repeating pattern can be a grid formed by applying pressure to the first or the second principal surface in a pattern of a first set of substantially parallel lines and applying pressure to the same principal surface in a pattern of a second set of substantially parallel lines, the first set of substantially parallel lines being substantially perpendicular to the second set of substantially parallel lines.The other surface, opposite the first or second principal surface, can be essentially flat, or it can define a corresponding grid pattern on the opposite principal surface. Optionally, the corresponding grid patterns on the first and second principal surfaces can be aligned along a Z-axis (thickness axis) of the porous layer. The repeating pattern can be a grid formed by applying pressure to the first or second principal surface in a pattern of a first set of essentially parallel lines and applying pressure to the other (opposite) principal surface in a pattern of a second set of essentially parallel lines, the first set of essentially parallel lines being essentially perpendicular to the second set of essentially parallel lines.

[0021] The porous layer of the composite sealant can have an initial thickness (i.e., when it is not compressed or compacted) of approximately 50 µm to approximately 2000 µm.

[0022] The porous layer can have a specific density. It has this density when it is completely uncompressed or not compacted at all. This specific density can be increased by compression or compaction. In the context of the present invention, compression or compaction means the removal of air or the reduction of the thickness of the porous layer. This can be achieved by applying force and / or by other means, such as the application and evaporation of certain liquids (e.g., isopropyl alcohol). In the context of the present invention, the density of the polymer material of the porous layer refers to the density after the air has been completely removed from the porous layer by compression or compaction. In this case, the porous layer is completely compacted. In embodiments where the porous layer comprises ePTFE, the density of the polymer material is 2.20 g / cm³. 3This corresponds to the density of the remaining nodal and fibril structure after the air has been removed from the ePTFE layer. In the context of the present invention, "uncompacted" and "compacted" sections mean that these sections are partially compacted, but to a greater or lesser degree relative to each other, ranging from complete compaction to no compaction at all. Uncompacted sections are less dense than compacted sections. They may be completely uncompacted / uncompressed or compacted to some degree. They are of the same density as the completely uncompressed porous layer or denser. Compacted sections are compacted to a greater degree than uncompacted sections. They may be as dense as the completely compacted porous layer.One method for determining whether the porous layer has been fully compacted involves weighing the porous layer and dividing the weight by the volume of the layer (thickness x length x width). For porous ePTFE layers, if the result was 2.20 g / cm³, then the layer was fully compacted. 3 The result is that all air has been removed and the porous layer has been completely compacted. If the result is not 2.20 g / cm², then... 3 If the porous layer is partially compacted, some air remains in the structure.

[0023] The uncompacted sections of the porous layer can have a density of approximately 1% to 90% of the density of the polymer material of the porous layer. The uncompacted sections of the porous layer can have a density of approximately 1% to 80%, or approximately 10% to approximately 70%, or approximately 20% to approximately 60%, or approximately 30% to approximately 50%, or approximately 1% to approximately 50%, or approximately 10% to approximately 50%, or approximately 20% to approximately 50%, or approximately 30% to approximately 50%, or approximately 40% to approximately 50%, or approximately 50% to approximately 90%, or approximately 60% to approximately 90%, or approximately 70% to approximately 90%, or approximately 80% to approximately 90% of the density of the polymer material of the porous layer.

[0024] The densified sections of the porous layer can have a density of approximately 30% to approximately 100% of the polymer material of the porous layer. The densified sections of the porous layer can have a density of approximately 40% to approximately 100%, or approximately 50% to approximately 100%, or approximately 60% to approximately 100%, or approximately 70% to approximately 100%, or approximately 80% to approximately 100%, or approximately 90% to approximately 100%, or approximately 30% to approximately 50%, or approximately 40% to approximately 50%, or approximately 40% to approximately 60%, or approximately 50% to approximately 70%, or approximately 60% to approximately 80%, or approximately 70% to approximately 90% of the polymer material of the porous layer.

[0025] The porous layer can be a porous ePTFE layer. The ePTFE layer can have a density of approximately 0.02 g / cm³. 3 up to approximately 1.98 g / cm³ 3 The ePTFE layer can have a density of approximately 0.02 g / cm³. 3 up to approximately 1.90 g / cm³ 3 or of approximately 0.02 g / cm³ 3up to approximately 1.80 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.70 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.60 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to about 1.50 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.40 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.30 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to about 1.20 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.10 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 1.00 g / cm² 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.90 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.80 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.70 g / cm³ 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.60 g / cm² 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.50 g / cm² 3 or of approximately 0.02 g / cm³ 3 up to approximately 0.40 g / cm² 3or of approximately 0.02 g / cm³ 3 up to approximately 0.30 g / cm² 3 , of approximately 0.02 g / cm³ 3 up to approximately 0.20 g / cm³ 3 , of approximately 0.02 g / cm³ 3 up to approximately 0.10 g / cm² 3 The ePTFE layer can have a density of approximately 0.10 g / cm³. 3 up to approximately 0.90 g / cm³ 3 or of about 0.20 g / cm² 3 up to approximately 0.90 g / cm³ 3 or of about 0.30 g / cm² 3 up to approximately 0.90 g / cm³ 3 or of about 0.40 g / cm² 3 up to approximately 0.90 g / cm³ 3 or of approximately 0.50 g / cm² 3 up to approximately 0.90 g / cm³ 3 or of about 0.60 g / cm² 3 up to approximately 0.90 g / cm³ 3 or of about 0.70 g / cm² 3 up to approximately 0.90 g / cm³ 3 , of approximately 0.80 g / cm³ 3 up to approximately 0.90 g / cm³ 3 The ePTFE layer can have a density of approximately 0.10 g / cm³. 3 up to approximately 0.50 g / cm² 3 or of about 0.20 g / cm² 3 up to approximately 0.50 g / cm² 3 or of about 0.30 g / cm²3 up to approximately 0.50 g / cm² 3 or of about 0.30 g / cm² 3 up to approximately 0.60 g / cm² 3 or of about 0.40 g / cm² 3 up to approximately 0.60 g / cm² 3 or of approximately 0.50 g / cm² 3 up to approximately 0.70 g / cm³ 3 or of approximately 0.50 g / cm² 3 up to approximately 0.70 g / cm³ 3 , of approximately 0.60 g / cm³ 3 up to approximately 0.80 g / cm³ 3 , of approximately 0.70 g / cm³ 3 up to approximately 0.80 g / cm³ 3 or of approximately 0.08 g / cm³ 3 up to approximately 1.98 g / cm³ 3 or of approximately 0.06 g / cm³ 3 up to approximately 1.70 g / cm³ 3 or of approximately 0.04 g / cm³ 3 up to approximately 1.00 g / cm² 3 or of approximately 1.00 g / cm² 3 up to approximately 1.90 g / cm³ 3 or of about 1.10 g / cm³ 3 up to approximately 1.80 g / cm³ 3 or of about 1.20 g / cm³ 3 up to approximately 1.60 g / cm³ 3 or of about 1.50 g / cm² 3 up to approximately 1.98 g / cm³ 3 or of about 1.60 g / cm³ 3 up to approximately 1.80 g / cm³ 3or of about 1.30 g / cm³ 3 up to approximately 1.70 g / cm³ 3 or of about 1.10 g / cm³ 3 up to about 1.50 g / cm³ 3 or of about 1.20 g / cm³ 3 up to approximately 1.60 g / cm³ 3 or of about 1.40 g / cm³ 3 up to approximately 1.98 g / cm³ 3 exhibit.

[0026] The sealant may include compacted sections forming a grid of compressed porous material (e.g., compressed or compacted ePTFE) with a density of approximately 0.66 g / cm³. 3 up to approximately 2.20 g / cm³ 3 The compacted sections can have a density of approximately 0.66 g / cm³. 3 up to approximately 2.20 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 2.10 g / cm³ 3 or of approximately 0.80 g / cm² 3 up to approximately 2.20 g / cm³ 3 or of approximately 0.90 g / cm² 3 up to approximately 2.20 g / cm³ 3 or of approximately 1.00 g / cm² 3 up to approximately 2.20 g / cm³ 3 or of about 1.10 g / cm³ 3up to approximately 2.20 g / cm³ 3 or of about 1.20 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.30 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.40 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.50 g / cm² 3 up to approximately 2.20 g / cm³ 3 or of about 1.60 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.70 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.80 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of about 1.90 g / cm³ 3 up to approximately 2.20 g / cm³ 3 or of approximately 2.00 g / cm² 3 up to approximately 2.20 g / cm³ 3 or of about 2.10 g / cm³ 3 up to approximately 2.10 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 2.0 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.90 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.80 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.70 g / cm³ 3or of about 0.66 g / cm³ 3 up to approximately 1.60 g / cm³ 3 or of about 0.66 g / cm³ 3 up to about 1.50 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.40 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.30 g / cm³ 3 or of about 0.66 g / cm³ 3 up to about 1.20 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.10 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 1.00 g / cm² 3 or of about 0.66 g / cm³ 3 up to approximately 0.90 g / cm³ 3 or of about 0.66 g / cm³ 3 up to approximately 0.80 g / cm³ 3 or of approximately 0.90 g / cm² 3 up to approximately 1.80 g / cm³ 3 or of approximately 0.80 g / cm² 3 up to approximately 1.00 g / cm² 3 or of approximately 1.00 g / cm² 3 up to about 1.50 g / cm³ 3 or of approximately 0.80 g / cm² 3 up to approximately 1.10 g / cm³ 3 or of approximately 0.90 g / cm² 3 up to approximately 1.40 g / cm³ 3 or of about 1.10 g / cm³ 3up to approximately 1.30 g / cm³ 3 or of about 1.30 g / cm³ 3 up to approximately 2.00 g / cm³ 3 or of about 1.50 g / cm² 3 up to approximately 1.90 g / cm³ 3 or of about 1.80 g / cm³ 3 up to approximately 2.00 g / cm³ 3 exhibit.

[0027] The porous layer (e.g. ePTFE) can be compressed under a pressure of about 1 MPa to at least about 60 MPa, or from about 12 MPa to at least about 60 MPa, or from about 16 MPa to at least about 32 MPa, or from 16 MPa or from 60 MPa to form the compacted sections.In embodiments where the compacted sections of the porous layer form a grid, the grid can have a line width of approximately 0.25 mm to approximately 5.00 mm, or of approximately 0.25 mm to approximately 4.50 mm, or of approximately 0.25 mm to approximately 4.00 mm, or of approximately 0.25 mm to approximately 3.50 mm, or of approximately 0.25 mm to approximately 3.00 mm, or of approximately 0.25 mm to approximately 2.50 mm, or of approximately 0.25 mm to approximately 2.00 mm, or of approximately 0.25 mm to approximately 1.50 mm, or of approximately 0.25 mm to approximately 1.00 mm, or of approximately 0.25 mm to approximately 0.50 mm, or of approximately 0.25 mm to approximately 1.25 mm, or of approximately 0.50 mm to approximately 1.75 mm, or of approximately 0.50 mm to approximately 1.50 mm or from about 0.50 mm to about 1.75 mm or from about 0.50 mm to about 1.50 mm or from about 0.25 mm to about 1.25 mm or from about 1 mm to about 5 mm or from about 2 mm to about 5 mm or from about 3 mm to about 5 mm or from about 4 mm to about 5 mm or from about 2 mm to about 4 mm or from about 1 mm to about 3 mm or from about 0.5 mm to about 2.00 mm.In embodiments in which the compacted sections of the porous layer form a grid, the grid can have a line width of approximately 0.40 mm to approximately 1.00 mm, or of approximately 0.40 mm to approximately 0.90 mm, or of approximately 0.40 mm to approximately 0.80 mm, or of approximately 0.40 mm to approximately 0.70 mm, or of approximately 0.40 mm to approximately 0.60 mm, or of approximately 0.50 mm to approximately 0.80 mm, or of approximately 0.60 mm to approximately 0.80 mm, or of approximately 0.42 mm to approximately 0.83 mm.

[0028] In embodiments where the densified sections of the porous layer form a grid, the space between the grid lines can be from about 1 mm to 10 mm, or from about 1.5 mm to about 4 mm, or from about 2 to about 8 mm, or from about 2 to about 6 mm, or from about 3 to about 6 mm, or from about 1 to about 4 mm. In embodiments where the densified sections of the porous layer form a grid, the space between the grid lines can be from about 2.0 mm to about 5.0 mm, or from about 2.5 mm to about 4.5 mm, or from about 3.0 mm to about 5.0 mm, or from about 3.5 mm to about 5.0 mm, or from about 4.0 mm to about 5.0 mm, or from about 2.5 mm to about 4.5 mm, or from about 2.5 mm to about 3.5 mm.

[0029] Without being bound to any specific theory, the compression range of the composite sealant can be defined by the geometry (line width) and relative thickness of the compressed porous layer and elastomer layers. The geometry (line width) and relative thickness of the compressed porous layer and elastomer layers can define the thickness of the composite sealant at the compressed sections (i.e., the "stiff sections"). For any given thickness, if the line width is narrow, the parameters can be adjusted so that, at the same given pressure, compression occurs to a thinner thickness due to the difference in form factor, thus giving the composite sealant more freedom to deform.

[0030] In use, the selectively compacted composite sealant exhibits high reversible deformation under compression. When measured according to the percentage compression test described here, the sealant can be compressed to approximately 90% of its original size under a stress of 60 MPa. The selectively compacted composite sealant can be compressed under a load of approximately 60 MPa, according to the percentage compression test described here, to a deformation in the range of approximately 10% to approximately 90%, or approximately 30% to approximately 70%, or approximately 20% to approximately 60%, or approximately 50% to approximately 90%, or approximately 70% to approximately 90%, or approximately 10% to approximately 60%, or approximately 30% to approximately 85%.

[0031] The sealant can maintain its structural integrity in a temperature range of approximately -50 °C to at least approximately 100 °C. The sealant can be impermeable to stress fluids (e.g., water, organic solvents, fuel) in a temperature range of approximately -50 °C to at least approximately 100 °C. The sealant can be designed to maintain a liquid seal (e.g., at a joint between multiple parts) in a temperature range of approximately -50 °C to at least approximately 100 °C. Generally, the dense sections of the porous layer and the elastomer of the elastomer layer are impermeable to fluids. The dense sections of the porous layer and the elastomer of the elastomer layer can be impermeable to stress fluids, such as water, organic solvents, jet fuels, hydraulic fluids, oils, de-icing agents, and the like.The compacted sections of the porous layer and the elastomer of the elastomer layer can be resistant to chemical attack, for example by common solvents, e.g. by various stress fluids, including, but not limited to, water, jet fuel, hydraulic fluids (including those based on phosphate esters), oils, de-icing agents or other materials.

[0032] In a second aspect, a method for forming a selectively densified composite sealant is provided. The method includes providing a porous membrane with an initial density and compressing the porous membrane in a pattern to form a selectively densified porous layer. The selectively densified porous layer has a first primary surface and an opposing second primary surface, and the pattern of compressed and uncompressed sections forms respective valleys and peaks in at least one of the first and / or the second primary surface of the porous layer. The method further includes coating the first primary surface with a first elastomeric material or elastomeric material precursor to form a first elastomeric layer arranged on the first planar primary surface.The first and / or second elastomer material can be applied in a single coating or in multiple (i.e., two or more) layers. The first and / or second elastomer material can comprise a single elastomer or more than one elastomer. In some embodiments, the first and / or second elastomer material comprises 2, 3, 4, 5, or 6 layers of elastomer. The elastomer material is cured to form the composite sealant.

[0033] The process can include coating the second primary surface of the selectively densified porous layer with a second elastomeric material to form a second elastomeric layer arranged on the second planar primary surface. The second elastomeric material can be the same as the first elastomeric material, or the first and second elastomeric materials can be different. The selectively densified porous layer can be coated with the elastomeric material without the elastomeric material being incorporated into the non-densified areas. In other words, the selectively densified porous layer can be coated with the elastomeric material without the elastomeric material entering or becoming trapped in the pores of the non-densified areas of the porous layer. The elastomeric material can be partially incorporated during the coating process, i.e., partially penetrate the non-densified areas.

[0034] Prior to coating the selectively densified porous layer with the elastomeric material, the process may further include the step of applying a barrier film to the porous layer before compression or to the selectively densified porous layer after compression. The barrier film may be designed to prevent the elastomeric material from penetrating the non-densified areas of the selectively densified porous layer. The barrier film may be deposited on the selectively densified porous layer either before or after compression to form the pattern of selectively densified regions.

[0035] The process may further include the step of applying adhesive to an outer surface of the first elastomeric material or to an outer surface of the second elastomeric material. The adhesive may be applied intermittently, for example, as individual dots. Alternatively, the adhesive may be applied as a continuous layer. Without being bound to any specific theory, the addition of an adhesive to the outermost surface(s) of the composite sealant may simplify the application of the composite sealant by a user and may reduce the displacement effects of lateral forces on the composite sealant. List of characters

[0036] The present revelation is better understood in light of the accompanying non-restrictive figures. Fig. Figure 1 is a side cross-sectional view of an embodiment of a selectively compacted composite sealant. Fig.Figure 2 is a top view of the selectively compacted composite sealant made of Fig. 1. Fig. Figure 3 is a lateral cross-sectional view showing exemplary steps for producing a selectively compacted composite sealant. Fig. Figure 4 is a side cross-sectional view of a second embodiment of a selectively compacted composite sealant. Fig. Figure 5 is a lateral cross-sectional view of a third embodiment of a selectively compacted composite sealant. Fig. Figure 6 is a lateral cross-sectional view showing an example of a selectively compacted composite sealant that is spot-coated with interrupted adhesive and undergoes compression. Fig. Figure 7 is a side cross-sectional view showing an example of a selectively compacted composite sealant with a continuous adhesive layer. Fig.8A is a scanning electron microscopy (SEM) image of a cross-section of the selectively compacted composite sealant from Example 3. Fig. 8B is a SEM image of a cross-section of the selectively compacted composite sealant from Example 9. Fig. 8C is an enlarged SEM image of the selectively compacted composite sealant from Example 9 ( Fig. 8B). Fig. 8D is a SEM image of a cross-section of the selectively compacted composite sealant from Example 15. Fig. 8E is an enlarged SEM image of the selectively compacted composite sealant from Example 15 ( Fig. 8D). Fig. Figure 9 is a schematic representation of a process for producing a selectively compacted composite sealant. Fig. 10A and Fig. Figure 10B shows images of a selectively compacted composite sealant according to one embodiment, wherein the sealant was immersed in colored liquid. Fig. 10A shows the sealant immediately after immersion in the liquid and Fig. Figure 10B shows the sealant 10 hours after immersion in the liquid.

[0037] Although the following is suitable for various modifications and alternative forms, specific embodiments are illustrated by way of example in the drawings and are described in detail below. However, it is not intended to limit the claims to the specific embodiments described. Rather, the description is intended to cover all modifications, equivalents, and alternatives thereof. DETAILED DESCRIPTION

[0038] Several embodiments disclosed herein generally relate to dry sealants for protecting a mechanical interface, for example, in an aircraft structure or a similar structure. In certain embodiments, a dry sealant may be formed from a porous membrane material compressed into a pattern to create selectively compressed areas within a selectively compressed membrane, with the spaces between the selectively compressed areas being filled by an elastomer. Suitable elastomers are chemically inert to one or more potential stress fluids, such that the elastomer limits the ability of fluids to penetrate the interface to prevent corrosion, fluid ingress, or other problems.Suitable elastomers can be formed from a chemically inert material to prevent the ingress of water, jet fuel, hydraulic fluids (including those based on phosphate esters), oils, de-icing agents or other materials.

[0039] The selectively densified membrane, which is at least partially surrounded by the elastomer, can also be chemically inert with respect to at least one of the possible loading fluids and is not wettable by the loading fluid, at least in the selectively densified areas. Thus, non-densified and densified areas in the pattern of selectively densified areas in the membrane material form peaks and valleys in at least one of the first main surface and / or the second main surface of the porous layer, with the valleys being filled with the elastomer. The non-densified areas forming peaks are isolated from each other by the selectively densified areas and the elastomer, so that the non-densified areas form a pattern of low-density regions that are more compressible than the elastomer and that impart increased compressibility to the dry sealant as a whole.

[0040] The porous layer (or membrane) can be a porous polymer or fluoropolymer, such as a porous membrane like an expanded polytetrafluoroethylene (ePTFE) membrane, a polypropylene membrane, or an expanded polyethylene membrane. The porous membrane and the elastomer are bonded together via the elastomer, which is deposited on the surface of the porous layer and forms around the features of the selectively densified porous layer to create a composite.

[0041] The elastomer can be any suitable elastomer that can be formed into a complex surface (e.g., a grooved or patterned surface). According to some embodiments, the elastomer can be a polymer designed to be deposited as a liquid, i.e., cast, molded, printed, or otherwise deposited, and then cured to retain its shape. Alternatively, the elastomer can be deposited by heat treatment, e.g., melting and deposition onto the porous membrane. The elastomer can be deposited in a single layer or in more than one layer. In some embodiments, the elastomer is deposited in 2, 3, 4, or 5 layers. In some embodiments, the elastomer comprises a single type of elastomer or a mixture of elastomers.In embodiments where the elastomer is applied in more than one layer, all elastomer layers may comprise the same elastomer, or the elastomer of all or some layers may be different. After setting and curing, the elastomer fills the valleys between uncompacted areas of the porous membrane, while the porous membrane is designed to be reversibly compressed under load to provide sealing capabilities with a high working range, i.e., capable of sealing a gap in an interface over a wide range of clamping pressures or between uneven surfaces. The elastomer may comprise an elastomer matrix containing one or more silicone, fluorosilicone, or perfluoropolyether elastomers. The elastomer may also include a fluoroelastomer.

[0042] The revelation is better understood by considering the figures in which identical parts have identical reference points.

[0043] Fig.Figure 1 is a side cross-sectional view of an embodiment of a selectively compacted composite sealant 100. The composite sealant 100 comprises a porous layer 102 and two elastomeric layers 104, 106 enclosing the porous layer between them. The porous layer 102 is selectively compacted in a pattern consisting of alternating compacted areas 108 and non-compacted areas 110, forming respective valleys and peaks in the porous layer. In some embodiments, the non-compacted areas 110 may remain substantially porous prior to compression. These valleys are filled by the elastomeric material of the first elastomeric layer 104. In the embodiment shown, the peaks and valleys are formed mainly in an upper boundary 116 of the porous layer, with the lower boundary 118 of the porous layer remaining relatively flat.In alternative embodiments, however, the porous layer 102 can be selectively densified more or less symmetrically.

[0044] The selectively compressed composite sealant 100 is capable of sealing large gaps and compressing to small thicknesses (e.g., by essentially removing all air from the pores of the compressed areas of the composite sealant). This functionality requires that the composite sealant be compressed under compressive force to high deformations. While the elastomeric material of the elastomeric layers 104, 106 alone may not possess sufficient compressibility to perform this function, the non-compressed sections 110 of the porous layer 102 effectively separate the elastomeric layers 104, 106 into a series of relatively narrow columns that can deform more readily under compressive force.

[0045] The relative densities of the sections can be adjusted to control the compressibility of the composite sealant 100 as a whole. For example, the density of the first elastomer layer 104 can vary both in a first partial thickness 122 of the elastomer in non-compacted areas 110 (i.e., the thinner thickness of the elastomer over the non-compacted sections 110) and in a second partial thickness 124 of the elastomer over the compacted areas 108 (i.e., the thickness of the elastomer "columns").

[0046] The porous layer 102 may be able to conduct liquid through it, except at compacted areas, i.e., as a side effect of the low density and high compressibility inherent in the composite sealing material 100 as a whole. Thus, the compacted areas 108 are compressed until the porous layer 102 in these areas can no longer be moistened under liquid loading. Without being bound to any theory, the compacted areas may become impervious to liquid loading due to the significantly reduced size and increased tortuosity of any remaining pore structure of the material after compaction.

[0047] The pattern of compacted areas 108 and uncompacted areas 110 can also vary in width and configuration. For example, the valley width 130, or the space between uncompacted areas 110, can vary from about 0.25 mm to about 2.00 mm, or from 0.5 mm to 1.0 mm. In some embodiments, the valleys can be inclined, in which case the width of each valley can vary from about 2 mm to about 50 µm from top to bottom. Similarly, the peak width 132, or the space between the valleys, can vary from about 1.5 mm to about 4 mm.

[0048] Selectively compacted composite sealants can also be formed in a range of thicknesses and accommodate various compressive deformations. For example, the thickness of the entire composite sealant can vary from approximately 10 µm to approximately 3000 µm, approximately 10 µm to approximately 2000 µm, approximately 10 µm to approximately 1000 µm, or from approximately 100 µm to approximately 600 µm. The compressive deformations that can be accommodated by selectively compacted composite sealants can also vary.

[0049] The selectively compressed composite sealants can be at least partially reversibly compressed when subjected to compression deformations ranging from approximately 10% to approximately 90% at 16 MPa. The selectively compressed composite sealants can be at least partially reversibly compressed when subjected to compression deformations of up to 90% at 60 MPa or up to 85% at 60 MPa. The selectively compressed composite sealants can be at least partially reversibly compressed when subjected to compression deformations ranging from approximately 30% to 85% at 60 MPa. For example, specific embodiments of selectively compressed composite sealants can be reversibly compressed when subjected to compression deformations ranging from approximately 15% to approximately 75% at 16 MPa or from 28% to 48% at 16 MPa.

[0050] The configuration of the pattern of compacted and non-compacted areas 108, 110 of the exemplary composite sealant 100 is shown in Fig. 2 shown in detail, which is a top view of the selectively compacted composite sealant made of Fig. 1. Fig.Figure 2 shows a rectangular arrangement of non-compacted areas 110 of the porous layer 102 surrounded by compacted areas 110 containing the filler material of the elastomeric layer 104. It should be noted that in a different (i.e., lower) section, the compacted areas 110 would contain the compacted sections of the porous layer 102. The pattern of compacted and non-compacted areas can be square or vary; that is, the valley widths 130 and 136 can be the same or different, as can the peak widths 132 and 134 of the non-compacted areas 110. In alternative embodiments, composite sealants with different patterns of compacted and non-compacted areas can be produced, the non-compacted areas generally surrounded and separated from each other by a filler of elastomeric material.For example, the pattern can be a square grid, a rectangular grid, a triangular or hexagonal grid, or any pattern of shaped, non-compacted areas surrounded by compacted filler. This separation prevents the penetration of liquid through the porous layer 102 when the composite sealant 100 is subjected to a liquid load from the side; that is, the fully compacted sections 110 and the elastomer layer 108 are impermeable to liquid and thus prevent liquid penetration beyond the first fully compacted section, acting as a seal.

[0051] Fig. Figure 3 is a side cross-sectional view showing exemplary steps in a process 300 for producing a selectively compacted composite sealant such as sealant 100 in Fig.Figure 1 shows various embodiments of the present disclosure. In a first stage 300A, an uncompacted porous layer 302 is selectively compressed into a pattern under a pattern of applied pressure 304. This pressure 304 can be applied, for example, by a grid-like tool with alternating teeth and gaps and can be carried out under heating. The pressure 304 can be applied in a pressure cell at pressures varying from about 1 MPa to at least about 60 MPa, or from about 16 MPa to at least about 60 MPa, or from about 22 MPa to about 23 MPa. The final densities of the compacted areas 306 can range from about 0.08 g / cm³. 3 up to approximately 0.55 g / cm² 3 , or of about 0.40 g / cm³ 3 up to approximately 0.60 g / cm² 3vary. Within the scope of the present disclosure, tool separation refers to the distance between embossed surfaces of the tool used to compress the material and form the compacted regions 306. This separation becomes the geometry of the non-compacted regions 308 in the selectively compacted composite (e.g., squares in a grid). Although various patterns can be implemented in the compaction step, the tool separation resulting in the non-compacted areas 308 can vary from about 1.5 mm to about 4 mm or from about 1.5 mm to about 2.5 mm or from about 1.5 mm to about 2 mm or from about 2 mm to about 2.5 mm or from about 2 mm to about 4 mm or from about 2.5 mm to about 4 mm or from about 3 mm to about 4 mm or from about 3.5 mm to about 4 mm or from about 2 mm to about 3 mm or from about 2.5 mm to about 3 mm or be about 2 mm.

[0052] In the second stage 300B for producing the selectively densified composite sealant, the elastomer layer 314 is added to the selectively densified porous layer 302. This elastomer layer 314 can be added as one or more layers of a liquid composite precursor or deposited using any other comparable agent. For example, the elastomer layer 314 can be added as a liquid elastomer precursor and then formed to a uniform thickness by, for example, scraping off excess 316 using a peeling tool 318.

[0053] The elastomer layer 314 is added to both surfaces of the porous layer 302 simultaneously or in two separate steps. Alternatively, the elastomer can be deposited as a layer on each surface of the porous layer and then exposed to heat to melt or soften in order to fill the valleys of the densified sections of the porous layer.

[0054] After coating, the elastomer must be cured. The elastomer can be cured after heat treatment. The curing temperatures and times can vary depending on the selected elastomer and thickness. The sequence of the heat exposure process steps can also vary. In the third stage 300C for producing the selectively compacted composite sealant, the elastomer layer 314 is set by heat treatment 320 and cures to form a tack-free composite. The composite sealant can be cured by oven curing for at least 5 minutes, for example, for about 5 minutes to about 10 minutes, at a temperature of about 100 °C to about 200 °C. In some embodiments, each side of the porous layer 302 can be treated individually, for example, after each layer of elastomer has been applied to each side (or main surface), and the process steps can then be repeated for the other side (i.e., the other side).the other (from the first or second main surface) of the composite material can be repeated. In other embodiments, the heat treatment can be carried out after both sides have been coated with elastomer.

[0055] The internal structure of selectively compacted composite sealants can vary depending on the elastomer chosen, and in particular depending on whether the elastomer can be deposited and cured in one pass and whether the elastomer penetrates the porous layer, as in Fig. 4 shown. Fig. Figure 4 is a side cross-sectional view of a second embodiment of a selectively compacted composite sealant 400, which is related to the selectively compacted sealant 100 made of Fig.1-2. The porous layer 402 comprises alternating densified areas 404 of the porous layer and non-densified areas 406 of the porous layer. The valleys formed above the densified areas 404 are filled with an elastomeric layer 408, which covers the non-densified areas 406 more narrowly to form smooth upper and lower surfaces 416, 418 of the composite material 400. In the embodiment from Fig.4 The elastomer layer 408 comprises a first layer 410 of elastomer material and a second layer 412 of elastomer material with a first boundary 414 between the first and second layers 410, 412. The first layer 410 can be formed by a first deposition and curing process, followed by a second deposition and curing process to add a second layer 412. In some embodiments, several additional layering processes can be used to add layers of elastomer material stepwise, depending on the viscosity of the elastomer material during deposition and depending on whether the geometry of the valleys in the porous layer 402 allows the deposition of large amounts of elastomer material at once. For example, in some embodiments, two layers of the elastomer can be used on each side (resulting in a total number of layers in the composite membrane 4 (i.e., two layers on each side)).In some alternative embodiments, 3 layers, 4 layers or more can be used on each side.

[0056] The first layer 410 is also shown to partially penetrate the porous layer 402 in the non-compacted areas 406. In some embodiments, the deposited liquid elastomer material can partially penetrate the porous layer 402, further bonding the elastomer material to the porous layer 402 in a penetration or receiving area 420 down to a penetration depth shown as 422. In some embodiments, multiple layers of elastomer material can be added such that the first layer 410 minimally penetrates the porous layer 402 and then forms a barrier to prevent further penetration by a volume of elastomer material added in a second layer 412 or subsequent layers.

[0057] Fig.Figure 5 is a side cross-sectional view of a third embodiment of a selectively compacted composite sealant 500, which is related to the selectively compacted sealant 100 made of Fig. 1-2 is also similar. The porous layer 502 comprises alternating densified areas 504 of the porous layer and non-densified areas 506 of the porous layer. The valleys formed over the densified areas 504 are filled with an elastomer layer 508, which covers the non-densified areas 506 more narrowly. In the embodiment shown in this figure, a single elastomer layer 508 is deposited in a filling pattern to fill valleys between the non-densified areas 506, forming a smooth upper and lower surface 516, 518 of the composite material 500. Unlike the embodiment shown in Fig.4. The elastomer layer 508 can be separated from the non-compacted sections 506 of the porous layer 502 by an unmoistenable film or barrier layer 512, which prevents the penetration of elastomer into the non-compacted sections 506. The barrier layer 512 can be formed from any suitable non-porous film or membrane, such as, but not limited to, a polymer or fluoropolymer film. In some embodiments, the barrier layer 512 is a compression-compacted ePTFE film, an unmoistenable ePTFE film, an unmoistenable ePE film, a fluorinated ethylene propylene FEP, a BOPP thermolaminated film (BOPP – biaxially oriented polypropylene) comprising co-extruded BOPP and hot melt adhesive, or a similar layer. The non-moistenable film 512 can form an upper and a lower inner surface 520, 522 which can accommodate the elastomer material.

[0058] Selectively compacted composite sealants can include various adhesive coatings to further secure the seals in the applied state. Fig.Figure 6 is a side cross-sectional view showing an example of a selectively compacted composite sealant 600, which is spot-coated with an interrupted adhesive 620 and undergoes compression. The composite sealant 600 contains a porous layer 602 with alternating compacted areas 604 and non-compacted areas 606 in a pattern as described above. The pattern forms valleys adjacent to the compacted areas 604, which are filled with an elastomer layer 608 forming the outer surfaces of the composite, i.e., the upper surface 616 and the lower surface 618. A first set of interrupted adhesive areas 620 can be added to the composite 600 on the upper surface 616, and a second set of interrupted adhesive areas 622 can be added to the lower surface 618.These interrupted adhesive areas 620 can adhere to a joint when the composite material 600 is inserted between the first and second joined surfaces 624, 626 and adheres to it, thus simplifying the application of the composite sealant by a user and mitigating the displacement effects of lateral force on the composite sealant. When subjected to a load, the composite sealant 600 can be compressed from an initial thickness 628 to a final thickness 630, causing the sealant to deform around the adhesive joints 632 that contain the adhesive areas 620. This deformation under compression is sufficient to fully engage the outer surfaces 616, 618 with the joined surfaces 624, 626 around the adhesive joints 632, providing a seal between the adhesive joints.

[0059] In some embodiments, selectively compacted composite sealants can have continuous adhesive coatings. For example, Fig.Figure 7 shows a side cross-sectional view illustrating an example of a selectively compacted composite sealant 700 with continuous adhesive layers 720, 722. The composite sealant 700 contains a porous layer 702 with alternating compacted areas 704 and non-compacted areas 706 in a pattern as described above. The pattern forms valleys adjacent to the compacted areas 704, which are filled with an elastomer layer 708 forming the outer surfaces of the composite, i.e., the upper surface 716 and the lower surface 718. The first continuous adhesive layer 720 on the upper surface 716 and the second continuous adhesive layer 722 on the lower surface 718 can be used to bond the composite sealant 700 to connected surfaces during application and to help reduce displacement effects of any lateral forces on the seal.

[0060] Fig. 8A, Fig. 8B and Fig. C and Fig. Figures 8D and E show SEM cross-sectional images of the selectively compacted sealants from Example 3. Fig. 8B and Fig. C shows SEM cross-sectional images of the selectively compacted sealants from Example 9 and Fig. Figures 8D and E show SEM cross-sectional images of the selectively compacted sealants from Example 15. As can be seen in the cross-sectional images, there are compacted areas located between pockets of non-compacted areas of the porous layer. The porous layer has an elastomer layer on both sides. As shown in the Fig. As can be seen more clearly in D and E, the compacted areas either have no openings / pores or a reduced size of openings / pores compared to the non-compacted areas, thus preventing liquid from flowing through the compacted areas. This, in turn, makes the compacted areas impervious to moisture.

[0061] Fig. Figure 9 shows a schematic representation of a method for producing a selectively densified composite sealant 900. The method involves providing a porous membrane 902 (e.g., ePTFE, although other porous membranes are also provided), then applying pressure to selected areas of the porous membrane 902 to create densified areas 904 separated from each other by non-densified areas 906 (in this case in a grid pattern, but other patterns are also provided). Finally, an elastomer layer 908 is applied to the first main surface and, in this particular embodiment, also to the second main surface.

[0062] Fig. 10A and Fig. Figure 10B shows images of a selectively compacted sealant according to one embodiment. Fig. Figure 10A shows the sealant just before immersion in colored solvent. Fig.10B is an image of the selectively compacted sealant made of Fig. 10A, which was recorded 2 hours after immersion in the colored solvent. Fig. Figure 10B shows the area where the liquid entered through the cut edge of the sealant and also shows how the liquid stops at the grid line (compacted section). Accordingly, in Fig. 10B, a cessation of liquid penetration was observed. In this sealant, the right edge is cut close to the "white square" (uncompacted area), and accordingly, liquid penetration is more restricted in this area. TESTING PROCEDURES Thickness, density and percentage compression

[0063] To verify the physical thickness, density, and percentage compression metrics, the following procedures were performed. First, each sample of supported elastomeric foam was die-cut to a diameter of 2.263 cm, weighed on a precision balance, and then placed on a roller on an INSTRON 5565 dynamic mechanical analyzer (Instron Tool Works, Inc., MA, USA). A 1.786 cm diameter compression disc was placed on the sample. A stress-strain compression test was initiated, in which the analyzer head moved at a strain rate of 0.06 mm / min until a load of 0.74 N was reached. Combined with the mass and size of the compression disc, this resulted in a pressure of 3.45 kPa on the sample. The sample thickness was extracted at 0.3 MPa.0.3 MPa is the point used to assess the initial thickness, which is used in the thickness, density, and as the denominator in the equation for deformation (percent compression). Using this thickness and the previously measured mass, the density of each sample was calculated. After the analyzer reached 0.74 N, it continued to compress the sample at a strain rate of 0.6 mm / min while recording the load data on its load cell to generate a stress-strain curve. The compressive deformations on the sample were extracted at pressures of 1 MPa and 16 MPa to represent this curve. Hysteresis

[0064] Each specimen was die-cut to a predetermined diameter of approximately 8 mm and placed on a roller on an RS 17 Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE, USA). The specimens were "loaded" by compression to a target strain (described below) while the stress was measured to generate a stress-strain-load curve. The specimens were then "unloaded" by retracting the compression disc back to its original position while the stress was measured to generate a stress-strain-unload curve. Typically, the unload curves measured negligible or zero stress at a nominal strain before reaching 0 percent strain. The amount of compressive strain that continued to be applied to a specimen after no further compressive strain occurred during the unload curve was extracted as a metric for the specimen.The compression set is calculated by taking this unloading strain metric and dividing it by the peak compression strain on the specimen. The total energy difference in the loading and unloading curves was used to indicate the amount of mechanical energy that can be stored and returned by each specimen, rather than being lost as heat during cyclic compression. The total mechanical energy in each loading curve was calculated by approximating the definite integral between 0 percent strain and the peak strain achieved by the specimen. The total mechanical energy in each unloading curve was calculated by approximating the definite integral between the peak strain achieved by the specimen and the strain at which zero stress was reached (the compression set).The sustained percentage strain energy was calculated by taking the integral from the unloading curve and dividing it by the integral from the loading curve. Maintaining the tension

[0065] Each specimen was cut to a predefined diameter of approximately 8 mm using a die and placed on a roller on an RS 17 Dynamic Mechanical Analyzer (TA Instruments, New Castle, DE, USA). Each specimen was compressed to a target deformation while the material modulus was dynamically measured. While holding this target deformation, the material modulus was continuously monitored for a predefined period before the specimen was unloaded. The percentage of retained stress was calculated by dividing the modulus measured five minutes after reaching the target deformation by the modulus measured at the time the target deformation was reached. Liquid ingress / sealing

[0066] Each penetration sample was cut into a square shape with a centered hole using a die in a press. This cut sample was weighed and recorded as its mass before immersion. Each cut sample was compressed between a stainless steel plate and a polished plexiglass plate with the same surface dimensions as the sample. Each stack was held together with a machine screw and a lock nut. The percentage compression of each sample was determined by comparing the micrometer measurement of the stack height without a sample to that of an uncompressed and a compressed sample. Once the target percentage compressions were achieved, each stack was immersed in JP8 jet propellant up to the side of the glass plate and photographed from above through the glass to visually inspect for liquid penetration over a period of 2 hours.The deformation of the penetration seal is then estimated by comparing the percentage compression with the stress-strain relationship described above. The fluid penetration test is passed if the specimen shows a cessation of fluid penetration when the fluid stops at the compacted section (represented by the absence of color uptake beyond the compacted section).

[0067] Further details of the revelation are described in connection with the following examples. EXAMPLES

[0068] A selectively densified composite sealant was constructed using a porous layer (ePTFE in these examples) with an initial thickness of approximately 0.1 mm to approximately 0.56 mm and at least one layer of elastomer on each side of the porous layer. The porous layer can have a density of approximately 0.02 g / cm³. 3 up to approximately 1.00 g / cm² 3In some embodiments, the porous layer can have a density of approximately 0.04 g / cm³. 3 up to approximately 0.55 g / cm² 3 exhibit.

[0069] The elastomer can be any suitable elastomer that is impermeable to stress fluids (e.g., water, jet fuel, common solvents such as organic solvents, de-icing fluid). In these examples, silicone (SS-2321 from Silicone Solutions), fluorosilicone (SILASTIC FL 60-9201 from DOW), or perfluoropolyether (SIFEL 2618 from Shin-Etsu Chemical Co. Ltd.) elastomers were selected. The elastomer must be usable within the desired temperature range for the intended application. For example, in some embodiments, the elastomer is a wide-temperature elastomer that can be used over a broad temperature range. For example, for aerospace applications, the elastomer may be a wide-temperature elastomer that can be used from approximately -50 °C to at least approximately 100 °C. The elastomer may include an elastomer precursor that is liquid at room temperature.

[0070] A compression tool was created with a raised pattern, which in these examples was a grid pattern. In the examples shown in Table 1, the compression tool was designed to imprint one of two imprint geometries (1 or 2) onto the porous layer. Both geometries were pressed at a pressure between 3000 and 4000 psi (approximately 3300 psi). Geometry 1 has a grid line width of 0.83 mm and a grid line spacing of 2 mm. Geometry 2 has a grid line width of 0.83 mm and a grid line spacing of 5 mm. The first major surface of the porous layer was compressed with the compression tool at a pressure of approximately 20 MPa to at least approximately 27 MPa using a hydraulic press. After the compression step, a selectively compacted porous layer was obtained. This layer exhibited compacted sections that defined a continuous path interspersed with uncompacted sections.The uncompacted sections of the porous layer can have a density of approximately 1% to 90% of the density of the porous layer. The compacted sections of the porous layer can have a density of approximately 30% to 100% of the density of the porous layer. The compacted sections of the porous layer and the elastomer of the elastomer layer can be impermeable or non-moistenable to the load fluid, such as water, organic solvents, jet fuels, hydraulic fluids, oils, de-icing agents, and the like.

[0071] The compression step was applied only to one of the first or second main surfaces of the porous layer. In these embodiments, the surface to which the compression step was applied defines a patterned topography (e.g., peaks (uncompacted sections) and valleys (compacted sections)). The surface opposite the first or second main surface (the main surface to which the compression step was not applied) may be flat or may also define a patterned topography.

[0072] However, the compression step can also be applied to the first main surface and the second main surface of the porous layer to create a pattern of compacted and uncompacted sections on both the first and second main surfaces.

[0073] In these examples, grid patterns were generated by applying pressure with a compression tool in a grid pattern only on the first primary surface. However, a grid pattern can also be generated by applying pressure with a compression tool in a pattern of parallel lines on the first primary surface and applying pressure with a compression tool in a pattern of parallel lines on the second primary surface, wherein the set of parallel lines on the first primary surface is arranged at an angle (e.g., substantially 90°) with respect to the set of parallel lines on the second primary surface of the porous layer. In some embodiments, the compression step can be applied only to the first primary surface, and the second primary surface can remain substantially flat.

[0074] Following compression, the selectively compacted porous layer on the first main surface (which exhibited the respective peaks and valleys in the pattern of the compression tool) was coated with the elastomer by sliding the edge of a glass ruler stripping tool across the surface of the film, thereby pressing a small accumulation of elastomer precursor onto an essentially flat surface of the composite sealant. The first main surface comprised areas with a thin elastomer layer over the uncompacted areas of the porous layer and thick elastomer "columns" over the compressed areas (valleys) of the porous layer.

[0075] The straight edge was angled relative to the compressed grid. The surface of the coated porous layer was essentially flat and, where appropriate, essentially smooth. After the initial coating, the structure was placed in an oven for 10 minutes at 150 °C or 5 minutes at 200 °C to cure the elastomer to a 'tack-free' state (partial curing).

[0076] In some embodiments, the structure was inverted, and the same coating and curing process was repeated on the opposite side (the second primary surface) of the selectively compressed layer. In embodiments where the second primary surface was not subjected to a compression step, the thickness of the elastomer layer can be substantially uniform along the entire second primary surface. In embodiments where the second primary surface was subjected to a compression step, the second primary surface comprised areas of thin elastomer over the uncompressed areas of the porous layer and thick elastomer "columns" over the compressed areas (valleys) of the porous layer. The structure was placed in an oven for 5 to 10 minutes at a temperature of 100°C to 200°C according to the oven cycle column in Table 1 to cure the elastomer to a "tack-free" state.

[0077] In some embodiments, the coating and partial curing steps were repeated several times. In these embodiments, the elastomer layer comprises more than one elastomer coating. The elastomers in each of the elastomer coatings can be the same or different. Each of the examples uses the same elastomer throughout a given structure. In the two-layer elastomer examples, a single layer of elastomer is applied to each side of the porous layer. After the first coating and oven cycle, the second surface was coated. The next oven cycle was the "curing" cycle at 100 °C for 60 minutes. In the four-layer elastomer examples, there are two layers of elastomer on each side of the porous layer. After the first coating and oven cycle, the second surface was coated. The next oven cycle was the "curing" cycle at 100 °C for 60 minutes.After completion, another layer of elastomer was applied to the first surface, followed by the "tack-free" oven cycle in Table 1. Then, a second layer of elastomer was applied to the second surface (fourth total layer), followed by another "hardening" oven cycle.

[0078] In some embodiments, a barrier layer was incorporated between the elastomer and the porous layer. In these examples, the barrier layer is a 0.006 mm thick compression-molded ePTFE with a 0.001 mm FEP coating on one side. A piece of the barrier layer was adhesive-taped to each of two flat metal plates, with the FEP surface layer facing upwards. One plate was placed in a press heated to 265 °C, and the porous ePTFE was positioned on top of and in contact with the exposed FEP surface. Metal discs equal to the thickness of the porous ePTFE minus 0.001 to 0.002 inches were placed just beyond the perimeter of the porous ePTFE. The second plate was placed over the porous ePTFE, with the exposed FEP surface facing downwards in contact with the porous ePTFE.The stack was compressed for at least 20 minutes with approximately 700 pounds of force to ensure that the FEP layers adhered to every surface of the porous ePTFE. Afterward, the barrier layer and the ePTFE composite could then be selectively compacted and coated.

[0079] The resulting selectively compressed sealant (i.e., the complete sealant laminate) can have a total thickness of approximately 50 µm to approximately 3000 µm in its uncompressed state. The sealant can be compressed under a load of approximately 60 MPa to up to approximately 90% elongation. The sealant can maintain its structural integrity in a temperature range of approximately -50 °C to at least approximately 100 °C. The sealant can remain impermeable to liquids (e.g., water, organic solvents, fuel) in a temperature range of approximately -50 °C to at least approximately 100 °C.

[0080] Several embodiments carried out according to this method are shown in Tables 1 to 3 below. Fig. 8A, Fig. 8B and Fig. C and Fig. Figures 8D and E show SEM cross-sectional images of the selectively compacted sealants from Example 3. Fig. 8B and Fig. C shows SEM cross-sectional images of the selectively compacted sealants from Example 9 and Fig. Figures 8D and E show SEM cross-sectional images of the selectively compacted sealants from Example 15. (Technical details of these examples are listed in Tables 1 and 2 below). TEST DATA Table 1 - Raw materials and processing in all examples: Example Nr . ePTFE thickness (mm) ePTFE density (g / cm3) Barrier layer Number of Coatings Elastomer Embossing geometry ID Oven cycle (°C, min) 1 0,561 0,55 Yes 2 Silicone (SS-2321) 1 150, 10 2 0,561 0,55 No 4 Silicone (SS-2321) 1 150, 10 3 0,561 0,55 No 4 Silicone (SS-2321) 2 150, 10 4 0,561 0,55 No 2 Silicone (SS-2321) 2 150, 10 5 0,231 0,42 No 4 Silicone (SS-2321) 1 150, 10 6 0,231 0,42 Yes 2 Fluorosilicone (FL 60-9201) 1 200,5 7 0,561 0,55 Yes 2 Fluorosilicone (FL 60-9201) 1 200,5 8 0,561 0,55 No 4 Fluorosilicone (FL 60-9201) 1 200,5 9 0,231 0,42 No 4 Fluorosilicone (FL 60-9201) 1 200,5 10 0,231 0,42 Yes 2 Silicone (SS-2321) 1 150, 10 11 0,561 0,55 Yes 2 Silicone (SS-2321) 1 150, 10 12 0,231 0,42 No 2 Fluorosilicone (FL 60-9201) 1 200,5 13 0,561 0,55 No 2 Fluorosilicone (FL 60-9201) 1 200,5 14 0,367 0,08 No 4 Silicone (SS-2321) 1 150, 10 15 0,367 0,08 No 2 Silicone (SS-2321) 1 150, 10 16 0,561 0,55 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 17 0,561 0,55 No 4 Perfluoropolyether (Sifel 2618) 1 100, 10 18 0,231 0,42 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 19 0,231 0,42 No 4 Perfluoropolyether (Sifel 2618) 1 100, 10 20 0,367 0,08 No 4 Silicone (SS-2321) 2 150, 10 21 0,367 0,08 No 2 Silicone (SS-2321) 2 150, 10 22 0,561 0,55 No 2 Silicone (SS-2321) 1 150, 10 23 0,231 0,42 No 2 Silicone (SS-2321) 1 150, 10 24 0,104 0,04 No 2 Silicone (SS-2321) 1 150, 10 25 0,104 0,04 No 4 Silicone (SS-2321) 1 150, 10 26 0,367 0,08 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 27 0,367 0,08 No 4 Perfluoropolyether (Sifel 2618) 1 100, 10 28 0,561 0,55 Yes 2 Silicone (SS-2321) 1 150, 10 29 0,231 0,42 Yes 2 Silicone (SS-2321) 1 150, 10 30 0,104 0,04 Yes 2 Silicone (SS-2321) 1 150, 10 31 0,561 0,55 No 4 Silicone (SS-2321) 1 150, 10 32 0,561 0,55 No 4 Silicone (SS-2321) 2 150, 10 33 0,231 0,42 No 4 Silicone (SS-2321) 1 150, 10 34 0,561 0,55 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 35 0,231 0,42 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 36 0,367 0,08 Yes 2 Perfluoropolyether (Sifel 2618) 1 100, 10 37 0,561 0,55 No 4 Perfluoropolyether (Sifel 2618) 1 100, 10

[0081] Table 2 refers to the structural properties of each of the examples 1-37 discussed above. Exemplary thicknesses and densities were obtained at an applied standard pressure of approximately 0.3 MPa and percentage compression values ​​of approximately 1 MPa, approximately 16 MPa and approximately 60 MPa. Table 2 - Data on thickness, density and compression for examples of selectively compressed composite material: Example Nr . Thickness (mm) Density (g / cm3) % Compression at 1 MPa % Compression at 16 MPa % Compression at 60 MPa 1 0,3993 1,27 10,49 34,65 50,7 2 0,4114 1,38 3,6 23,89 46,2 3 0,5662 1,16 6,62 40,22 61,1 4 0,4915 1,05 9,56 39,13 54,2 5 0,2115 1,08 2,46 45,68 70,9 6 0,4297 1,34 1,92 31,45 63 7 0,7246 1,4 2,3 30,95 55,8 8 0,9899 1,4 2 35,91 67,2 9 0,7783 1,37 3,35 53,7 77,4 10 0,0837 1,47 2,14 14,54 30,8 11 0,3419 1,48 2,8 25,42 43,5 12 0,5162 1,3 3,44 43,3 69,7 13 0,6248 1,32 3,03 30,6 54,9 14 0,1972 1,01 5,72 60,37 79,7 15 0,1411 1,04 8,53 48,19 72 16 0,4076 1,48 5,52 21,8 41,6 17 0,4714 1,77 5,89 27,23 48,6 18 0,0989 1,46 4 23,47 38,3 19 0,1971 1,55 7,52 36,7 67,5 20 0,2877 0,83 15,27 69,02 84 21 0,1687 0,87 11,26 59,2 79,4 22 0,4427 1,32 10,6 31,22 51,6 23 0,1882 1,04 4,15 37,96 59,6 24 0,0971 1,15 2,93 52,44 81,6 25 0,0789 1,17 0,92 75,15 75,2 26 0,0523 1,3 7,23 28,45 38,8 27 0,1609 1,57 6,62 20,05 61,1 28 0,4915 1,37 5 32,89 52,6 29 0,085 1,53 2,4 16,14 32,7 30 0,043 1,25 6,04 21,42 38,5 31 0,5545 1,34 1,55 35 60,1 32 0,5395 1,08 10,34 40 57,1 33 0,1835 1,07 2,19 35,27 57,3 34 0,42 1,52 6,26 21,89 42,2 35 0,1325 1,29 9,41 25,09 37,1 36 0,1533 1,29 5,41 29,9 43,4 37 0,4797 1,83 2,97 15,27 39

[0082] As shown in Table 2, the exemplary selectively compressed composite sealants varied in thickness from about 43 µm to about 1.00 mm and in tolerated compression deformations from about 1% to 15% (at 1 MPa) or from about 14% to 75% (at 16 MPa) or from about 30% to about 84% (at 60 MPa), indicating a very high degree of compressibility of the exemplary selectively compressed composite sealants and the ability to adjust the compressibility with the material composition.

[0083] Table 3 lists hysteresis values ​​for deformation recovery for selected specimens, including the percentage retained deformation energy and the percentage compression strain residual after compression. The percentage retained deformation energy is a measure of how much restoring force the composite provides during recovery compared to the amount used to initially deform the composite. It is calculated based on the area under a stress-strain curve obtained when the specimen is unloaded versus the area under a stress-strain curve obtained when the specimen is loaded. Specifically, the percentage retained deformation energy can be defined as the deformation energy measured when the specimen is unloaded (after deformation) divided by the strain energy measured when the specimen is initially loaded.The compression set is a measure of the instantaneous compression upon unloading of a sample after an applied strain and is measured by the hysteresis test method described above. Table 3 - Voltage maintenance and hysteresis: Example Nr . Percentage withheld Tension (5 min) Hysteresis curve : Percentage withheld Deformation energy Hysteresis curve: % Compression deformation residue (Elongation at 0 Pa) , Relief) 3 48 23 87 8 73 26 25 19 55 50 25

[0084] As shown in Table 3, the exemplary selectively compressed composite sealants of Examples 8 and 19 exhibit good compression set behavior while maintaining an excellent compression range, achieving 75% recovery after compression with compression sets around 25% (based on the percentage of applied strain). The high retained stress energy, as demonstrated by the examples, suggests that they would be well suited as dynamic seals, as they possess good recoverability (indicated by the low compression set) while also maintaining good restoring force (required for sealing) during this recovery. The retained stress metric provides an indication of sealing performance over time, particularly for static connections.The combination of both compression set and retained deformation energy suggests good dynamic sealing capability, which was maintained by the exemplary selectively compacted composite sealants, indicating that the sealants would maintain good sealing over time. The combination of good parameters for retained stress, compression set, and retained deformation energy suggests a long-term seal for a dynamic joint.

[0085] The second column of Table 3 shows the percentage of retained stress in the specimens after a five-minute relaxation period during a constant strain of 25%. This value was obtained by measuring the modulus of each specimen both immediately after the application of peak strain and at a later time, and by dividing the modulus obtained five minutes after peak strain by the modulus at the time of peak strain. As shown in Table 3, the exemplary selectively compressed composite sealants generally retained a high percentage of the restoring force during constant compression, as indicated by the retained stress ratios in the range of 48% to 73%. This restoring force retention is very important for fastened assemblies and could, for example, relate to higher retained torque on bolts and higher retained pressures on rivets over time.

[0086] The selectively densified composite sealants disclosed here offer significantly higher compressibility than a pure elastomer, yet still achieve good performance in terms of stress retention and recoverability, while preventing fluid ingress. Selectively densified composite sealants similar to Example 8 exhibit particularly improved properties. Fig. Figure 10 clearly illustrates the prevention of liquid penetration achieved by selectively compacted composite sealants of the present disclosure.

[0087] For the sake of clarity and comprehensibility, the invention has now been described in detail. However, it is obvious to those skilled in the art that certain changes and modifications can be made within the scope of protection of the attached claims.

[0088] The preceding description has provided numerous details to facilitate understanding of various embodiments of the present disclosure. However, it is obvious to the person skilled in the art that certain embodiments can be implemented without some of these details or with additional details. Furthermore, specific materials and material properties, such as those described with reference to one embodiment (e.g., material densities, porosities, thicknesses, alternative materials, etc.), can be combined with or used instead of materials described in other embodiments, unless expressly stated otherwise.

[0089] Since several embodiments have been disclosed, it is obvious to the person skilled in the art that various modifications, alternative structures and equivalents can be used without deviating from the spirit of the embodiments.

[0090] In addition, a number of well-known processes and elements have been omitted to avoid unnecessarily obscuring the present disclosure. Accordingly, the foregoing description should not be considered as limiting the scope of the present disclosure or claims.

[0091] When a range of values ​​is provided, it is understood that any intermediate value, down to the smallest fraction of the unity of the lower bound, between the upper and lower bounds of that range is also specifically disclosed, unless the context explicitly requires otherwise. Any narrower range between any specified or unspecified intermediate values ​​within a specified range, and any other specified or intermediate value within that range, is covered. The upper and lower bounds of these narrower ranges may be independently included or excluded within the range, and any range in which one, neither, or both of the bounds are included in the narrower ranges is also covered by this disclosure, subject to any specifically excluded bound within the specified range.If the specified area includes one or both of the boundaries, areas that exclude one or both of these included boundaries are also included.

[0092] Within the scope of the present invention and in the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly indicates otherwise. Furthermore, when used in this description and in the following claims, the words "comprise", "comprehensive", "contains", "containing", "include", "including", and "includes" indicate the presence of specified features, integers, components, or steps, but do not preclude the presence or addition of one or more other features, integers, components, steps, actions, or groups. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 3953566

[0013] US 9926416

[0013]

Claims

[1] A selectively densified composite sealant comprising: a porous layer having a first major surface and an opposite second major surface, the porous layer comprising a porous membrane and having alternating densified portions and non-densified portions, the densified and non-densified portions forming respective valleys and peaks in at least one of the first and second major surfaces of the porous layer; at least one elastomer layer disposed on one or both of the first and second major surfaces, the at least one elastomer layer comprising an elastomer material filling the valleys in the first and / or second major surfaces of the porous layer, the non-compacted portions being discontinuous and separated by the compacted portions. [2] The sealant of claim 1, wherein the at least one elastomer layer comprises a first elastomer layer disposed on the first major surface, the first elastomer layer comprising a first elastomer material filling the valleys in the first major surface, and a second elastomer layer disposed on the second major surface, the second elastomer layer comprising a second elastomer material filling the valleys in the second major surface. [3] Sealant according to claim 2, wherein the first and second elastomeric materials are different elastomeric materials or wherein the first and second elastomeric materials are the same elastomeric material. [4] A sealant according to any preceding claim, wherein the porous membrane comprises expanded polytetrafluoroethylene (ePTFE). [5] A sealant according to any one of the preceding claims, wherein the elastomeric material comprises a fluoroelastomer. [6] Sealant according to one of the preceding claims, further comprising at least one barrier layer arranged between the porous layer and the at least one elastomer layer. [7] Sealant according to claim 6, wherein the porous layer is free of the elastomer material from the at least one elastomer layer. [8] Sealant according to claim 6 or 7, wherein the barrier layer is selected from the group comprising densified expanded polytetrafluoroethylene (ePTFE) and biaxially oriented polypropylene (BOPP). [9] Sealant according to one of claims 1 to 5, wherein the elastomeric material is partially incorporated into the non-compacted portions. [10] A sealant according to any one of the preceding claims, wherein the non-compacted portions have substantial remaining porosity. [11] A sealant according to any preceding claim, wherein the porous layer comprises a repeating pattern of the non-compacted portions and the compacted portions. [12] A sealant according to claim 11, wherein the repeating pattern comprises non-compacted sections arranged in a rectangular grid and separated from one another by the compacted sections. [13] A sealant according to any one of the preceding claims, wherein the compacted sections comprise a grid of compressed ePTFE having a density of 0.66 g / cm 3 up to 2.20 g / cm 3 has. [14] A sealant according to any preceding claim, wherein the compacted sections comprise a grid of compressed PTFE compressed to a pressure of about 12 to at least 60 MPa. [15] A sealant according to any preceding claim, wherein the densified portions comprise a grid of compressed ePTFE, the grid having a grid line width of 0.25 to 5.00 mm. [16] A sealant according to any preceding claim, wherein the compacted sections comprise a grid of compressed ePTFE, the grid having a grid line spacing of 1 mm to 10 mm. [17] Sealant according to one of the preceding claims, wherein the sealant has a total thickness of 10 to 5000 µm, preferably a total thickness of 100 to 600 µm. [18] Sealant according to any one of the preceding claims, wherein the sealant is compressed to a deformation of 10 to 90% or 30 to 70% under a load of 60 MPa. [19] Sealant according to any one of the preceding claims, wherein the sealant is structurally intact in a temperature range of -50 °C to at least 100 °C. [20] A sealant according to any one of the preceding claims, wherein the at least one elastomer layer comprises a first elastomer layer disposed on the first major surface, the first elastomer layer comprising a first elastomer material filling the valleys in the first major surface and; a second elastomer layer disposed on the second major surface, the second elastomer layer comprising a second elastomer material filling the valleys in the second major surface, and wherein the first elastomeric material and / or the second elastomeric material comprises a plurality of elastomeric layers. [21] Sealant according to any one of the preceding claims, wherein the compacted portions of the porous layer and the elastomeric material of the elastomeric layer are liquid-impermeable. [22] Sealant according to any one of the preceding claims, wherein the densified portions of the porous layer are designed to prevent the penetration of liquid into the sealant and are thus designed to seal a mechanical connection comprising sealant liquid. [23] A sealant according to any preceding claim, wherein the densified portions of the porous layer and the elastomeric material of the elastomeric layer are resistant to chemical attack by jet fuel and phosphate ester hydraulic fluid. [24] A method of forming a selectively densified composite sealant, the method comprising: Providing a porous layer having a first major surface and an opposite second major surface; Compressing the first major surface of the porous layer in a pattern to form a partially densified porous layer, the partially densified porous layer comprising alternating densified portions and non-densified portions forming respective valleys and peaks in the porous layer, the non-densified portions being discontinuous and separated by the densified portions; Coating the first major surface with a first elastomeric material to form a first elastomeric layer disposed on the first major surface, the first elastomeric layer comprising the first elastomeric material covering the densified and non-densified portions; and Curing the first elastomer layer to form the composite sealant. [25] The method of claim 24, further comprising compressing the second major surface of the porous layer in a pattern to form a partially densified porous layer, the partially densified porous layer comprising densified portions and non-densified portions forming respective valleys and peaks in the porous layer, the non-densified portions being discontinuous and separated by the densified portions, optionally wherein the second compression step is performed prior to the step of coating the first major surface with elastomeric material. [26] The method of claim 24 or 25, further comprising: Coating the second major surface with a second elastomeric material, optionally the same as the first elastomeric material, to form a second elastomeric layer disposed on the second major surface, the second elastomeric layer comprising the second elastomeric material covering the densified and non-densified portions. [27] A method according to any one of claims 24 to 26, wherein the first major surface is coated with the first elastomeric material without the first elastomeric material being incorporated into the non-compacted regions. [28] A method according to any one of claims 24 to 27, further comprising: Coating the first and / or second elastomer material with further elastomer material. [29] A method according to any one of claims 24 to 28, comprising heating the composite comprising the coated elastomeric material to at least partially cure the elastomeric material. [30] A method according to any one of claims 24 to 28, comprising: at least partially curing the elastomer(s) by heating the composite at a temperature of about 100°C to about 200°C for about 5 to about 10 minutes. [31] A method according to any one of claims 29 and 30, further comprising: further curing of the sealant at a temperature of approximately 100 °C to approximately 200 °C for at least 5 minutes. [32] A method according to any one of claims 24 to 31, further comprising: Applying a barrier material to a first and / or a second major surface of the porous layer prior to the compression step to form a barrier layer to prevent penetration of the elastomeric material into the partially compacted porous layer, this step optionally being a heat lamination step. [33] The method of any one of claims 24 to 32, further comprising applying adhesive to an outer surface of the first elastomeric material and / or to an outer surface of the second elastomeric material. [34] A method according to any one of claims 33, wherein the adhesive is applied intermittently, optionally applying the adhesive as discrete dots; or applying the adhesive as a continuous layer.

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