bulletproof panel

Abstract

To provide a material and process capable of using a hot bonding method and capable of reducing a flexure or scrap and manufacturing a bulletproof panel.SOLUTION: A bulletproof panel (100) including a core layer (102) having a first principal surface (104) and a second principal surface (106) is disclosed. The core layer comprises a bulletproof gel (112). A first layer (120) of a bulletproof material is arranged on the first principal surface of the core layer. A second layer (122) of the bulletproof material is arranged on the second principal surface of the core layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to ballistic panels and methods of manufacturing ballistic panels. [Background technology]

[0002] Ballistic panels are often used in applications requiring ballistic protection. Conventional ballistic panels include a multi-ply laminate of Kevlar fabric in an asymmetric panel construction, as shown in FIG. 1. The multi-ply laminate uses a single paper honeycomb core 10 approximately 1 inch thick. The paper includes a set of meta-aramid fibers pressed together. Each sheet of meta-aramid paper is coated with a series of horizontal rows of epoxy adhesive. The sheets are then laminated together and cured. The gaps between each bond line are then expanded to form hexagonal cells. Typically, the cells are hollow (e.g., air-filled). A 28-ply Kevlar laminate 20 impregnated with a curable epoxy resin is bonded to one side of the honeycomb core 10 with an adhesive layer 30. An aluminum face sheet 40 is bonded to the honeycomb core 10 and Kevlar laminate 20 with an additional adhesive layer 30. Bulletproof panels as shown in FIG. 1 are known to be used in aircraft cabin doors, for example, to protect pilots from terrorist threats.

[0003] Current panels, as shown in Figure 1, meet ballistic resistance and stiffness requirements in embodiments. However, because conventional panels are not symmetrical, warping occurs during heat curing. To reduce warping, cold bonding methods can be used to manufacture the ballistic panels shown in Figure 1. However, such cold bonding methods can result in longer panel manufacturing times and higher scrap rates compared to manufacturing methods using hot bonding, which is performed at higher temperatures.

[0004] Therefore, there is a need in the art for materials and processes that allow for the use of hot bonding methods and for producing ballistic panels with reduced warpage and scrap. Summary of the Invention

[0005] The present disclosure relates to a ballistic panel including a core layer having a first major surface and a second major surface, the core layer including a ballistic gel, a first layer of ballistic material disposed on the first major surface of the core layer, and a second layer of ballistic material disposed on the second major surface of the core layer.

[0006] The present disclosure also relates to a method for making a ballistic panel, the method including providing a core layer having a first major surface and a second major surface and including a ballistic gel, a first layer of ballistic material attached to the first major surface of the core layer, and a second layer of ballistic material attached to the second major surface of the core layer.

[0007] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure claimed. [Brief explanation of the drawings]

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0009] [Figure 1] 1 is a cross-sectional schematic diagram showing a conventional ballistic panel using a multi-layer laminate of Kevlar fabric in an asymmetric panel construction. [Figure 2] 1 is a cross-sectional schematic diagram illustrating a ballistic panel according to the present disclosure. [Figure 3] FIG. 1 is a perspective view illustrating cell walls forming a plurality of empty cells and a ballistic gel layer prior to being incorporated into the cells to form a cellular core layer in accordance with the present disclosure. [Figure 4] 1 is a cross-sectional schematic diagram illustrating a ballistic panel according to the present disclosure. [Figure 5] 1 is a cross-sectional schematic diagram illustrating a ballistic panel according to the present disclosure. [Figure 6] 1 is a cross-sectional schematic diagram illustrating a ballistic panel according to the present disclosure. [Figure 7] FIG. 7 is a cross-sectional schematic diagram illustrating a laminate structure that can be included as a core layer of the ballistic panel shown in FIG. 6 according to the present disclosure. [Figure 8] FIG. 1 illustrates a bullet-resistant door for an aircraft according to the present disclosure. [Figure 9] FIG. 1 is a flow diagram illustrating a method for making a ballistic panel according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the drawings, structural accuracy, detail, and scale are not strictly maintained, and some details are simplified or depicted to facilitate understanding of the present disclosure.

[0011] DETAILED DESCRIPTION OF THE DISCLOSURE The present disclosure will now be described in detail, examples of which are illustrated in the accompanying drawings, in which like reference numerals are used to refer to like elements throughout. In the following description, reference is made to the accompanying drawings, which form a part of this specification and which show, by way of illustration, specific embodiments for practicing the present disclosure. Accordingly, the following description is by way of example only.

[0012] Ballistic panels, such as those shown in FIG. 1, warp during hot-bonding due to differences in the coefficients of thermal expansion (CTE) of the panel components. This can result in lost time, costly repairs, and even the need to scrap the panel entirely. Furthermore, panel warpage often leads to some form of delamination in the panel components. Delamination in a panel results in the loss of many of the panel's key designed mechanical properties, such as a significant reduction in flexural strength. Composite panel warpage can result from asymmetrical stacking of the panel components after heating and subsequent cooling. In this case, the asymmetry is partially caused by the large, multi-layer Kevlar ballistic laminate 20 used to meet the panel's ballistic specifications and is laminated to only one side of the honeycomb core 10. Unfortunately, redistributing the Kevlar fabric plies into two smaller, separate laminates symmetrically positioned relative to the honeycomb core 10 would prevent the panel from meeting the ballistic specifications without further modifications. Furthermore, adding another laminate (e.g., a replica of the ballistic laminate 20) symmetrically to the structure may reduce warpage, but it would add significant weight and increase fuel consumption for the aircraft in which the panels are used, thereby significantly increasing costs to airline customers.

[0013] The symmetrical design of the ballistic panels disclosed herein allows for manufacturing using hot bonding techniques while reducing warpage to acceptable levels. Hot bonding utilizes relatively high temperatures, such as temperatures above 200°F, which allows for high production rates, for example, temperatures in the range of about 220°F to about 500°F. In one example, hot bonding can be performed at temperatures of about 275°F to about 300°F and a pressure of 80 PSI for 25-30 minutes. For example, a core layer containing ballistic gel-filled cells, or other core layer materials described herein, can be applied between two separate multi-layer laminates of ballistic resistant material to create a single bonded laminate structure that achieves the desired ballistic performance. In one embodiment, the density of the core layer containing ballistic gel-filled cells is lower than that of, for example, a Kevlar laminate, thereby providing a relatively lightweight ballistic resistant material.

[0014] 2 illustrates an example of a ballistic panel 100 according to the present disclosure. The ballistic panel includes a core layer 102 having a first major surface 104 and a second major surface 106. The core layer 102 includes cell walls 108 configured with a plurality of cells 110. A ballistic gel 112 is embedded in the plurality of cells 110 to form the cellular core layer. A first layer 120 of ballistic material is disposed on the first major surface 104 of the core layer 102. A second layer 122 of ballistic material is disposed on the second major surface 106 of the core layer 102. The ballistic gel acts as a second ballistic material, filling the gap between the two relatively thin layers 120, 122 of ballistic material.

[0015] FIG. 3 is a perspective view of the cell walls 108 before ballistic gel 112 is inserted into the cells 110. The cells 110 can be any suitable shape, such as a honeycomb shape with a hexagonal cross-section, as shown in FIG. 3. Alternatively, the cell cross-section can be square, rectangular, or another polygonal shape. The cell walls 108 can include any material suitable for containing ballistic gel 112 in a ballistic-resistant structure. For example, a suitable material is paper including a set of meta-aramid fibers pressed together. The cell wall material 108 can be manufactured by applying an epoxy adhesive in a series of horizontal rows across multiple sheets of meta-aramid paper. The meta-aramid papers are laminated together, and the adhesive is allowed to cure. The gaps between each bond line are then widened to form the hexagonal cells. Commercially available fabrics containing meta-aramid fibers suitable for making the cell walls 108 include, for example, NOMEX®, available from DuPont, Midland, Michigan. Nomex has aromatic groups all attached to the backbone at the 1 and 3 positions, as shown in Formula 1 below, where "n" is the number of repeating units. This is called a meta linkage. [ka]

[0016] The ballistic gel 112 may be any dilatant, non-Newtonian fluid that has the property of increasing stiffness upon impact with a bullet. An example of such a ballistic gel is D3O® Gel, commercially available from D3O Labs, London, UK. D3O is an energy-absorbing gel material comprising polyurethane and polyborodimethylsiloxane. D3O may be in the form of a foam, such as a closed cell polyurethane foam composite, which comprises polyborodimethylsiloxane (PBDMS) as a dilatant dispersed in a foam matrix.

[0017] The cell walls 108 provide rigidity to the composite panel, even though they would have little or no ballistic resistance without the D3O gel. The core layer 102 can have any thickness that provides the desired ballistic resistance. By way of example, the core layer thickness can be in the range of about 0.2 inches to about 5 inches, such as about 0.5 inches to about 2 inches, or about 0.5 inches to about 1 inch.

[0018] Both the first layer of ballistic resistant material 120 and the second layer of ballistic resistant material 122 may comprise any suitable ballistic resistant material. An example of a suitable material is a para-aramid fiber, such as Kevlar (polyparaphenylene terephthalamide) fiber, woven into a fabric and impregnated with a curable resin. In Kevlar fiber, all of the aromatic groups are attached to the backbone at positions 1 and 4, as shown in Formula 2 below, where "n" is the number of repeat units. This is referred to as a para linkage. [ka]

[0019] Multiple layers or plies of resin-impregnated Kevlar fiber fabric can be laminated together with the resin and cured. Approximately 5 to 20 plies of resin-impregnated fabric, e.g., about 10 to 20 plies, or about 10 to 15 plies, of the fabric can be included in each of the first layer of ballistic-resistant material 120 and the second layer of ballistic-resistant material 122. The resin can be any curable resin suitable for pre-impregnated laminates, such as epoxy resins. The resin can also be low heat release resins, including thermosetting resins such as phenolic resins, benzoxazine resins, and cyanate ester-based resins. Thermoplastic resins such as polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylsulfone (PPSU), polyphenylene sulfide (PPS), and polyetherimide (PEI) can also be used.

[0020] The thickness of each of the first layer of ballistic resistant material 120 and the second layer of ballistic resistant material 122 may be in the range of about 0.1 inches to about 0.5 inches, such as in the range of about 0.2 inches to about 0.4 inches.

[0021] The ballistic panel shown in FIG. 2 further includes a first face sheet 130 in the first layer 120 of ballistic-resistant material and a second face sheet 132 in the second layer 122 of ballistic-resistant material. By way of example, each of the first face sheet 130 and the second face sheet 132 includes aluminum, such as pure aluminum (e.g., 99% or more by weight Al) or an aluminum alloy. The face sheets, along with the core, provide bending stiffness. Additionally, face sheets including aluminum have properties that can help stop bullets and shrapnel.

[0022] First face sheet 130 and second face sheet 132 can have any desired thickness. Examples of suitable thicknesses are in the range of about 0.005 inches to about 0.04 inches, such as in the range of about 0.01 inches to about 0.03 inches.

[0023] FIG. 4 illustrates a ballistic panel 100 similar to that described above with reference to FIG. 2, except that the ballistic panel 100 illustrated in FIG. 4 includes an intumescent layer 140 and a decorative layer 160 on the first face sheet 130. The intumescent layer 140 functions to provide fire resistance to the ballistic panel 100. The intumescent layer includes an intumescent material, such as an organic material blend that forms a foam in the presence of heat. The intumescent material activates to form the foam at temperatures ranging from about 250°F to about 450°F, for example. The foam acts as a thermal barrier against heat penetration in the event of a fire. Because DO gel likely does not have the same flammability characteristics as the aramid core in which it is incorporated, the intumescent material may help provide the desired level of fire resistance to the panel. Commercially available foamable materials include, for example, VERSACHAR® resin, a thermoplastic foamable layer available from FlameOFF Coatings, Inc., based in Raleigh, North Carolina, or Ed Gregor and associates, Inc., of South Carolina. In other embodiments, fabric may be pre-impregnated with a foamable polymer, such as VERSACHAR®, which may be suitably combined with a composite laminate, where one or more plies of pre-impregnated fabric (prepreg) may be placed on the outer surface of the ballistic laminate. The foamable layer 140 may have any suitable thickness. By way of example, the thickness of the foamable layer 140 may be from about 0.001 inches to about 0.1 inches, such as from about 0.002 inches to about 0.01 inches.

[0024] A decorative layer 160 may be disposed on the ballistic panel 100. Such a decorative layer may include, for example, wallpaper, paint, a logo, or other desired layer applied to enhance the appearance of the panel. Such a decorative layer 160 may optionally be disposed on any of the ballistic panels described herein.

[0025] FIG. 5 illustrates a ballistic panel 100 similar to that shown in FIG. 2, except that the panel 100 includes a first flame-retardant layer 146 between the first layer 120 of ballistic-resistant material and the first face sheet 130, and a second flame-retardant layer 146 between the second layer 122 of ballistic-resistant material and the second face sheet 132. These flame-retardant layers may include one or more layers of fabric impregnated with a flame retardant, such as about 1 to 10 layers, about 1 to 5 layers, or about 1 to 3 layers. The fabric may be a ballistic-resistant material such as a woven para-aramid fiber (e.g., Kevlar® or other fabric). The flame-retardant material may be any suitable material, such as the intumescent materials described herein. An example of a commercially available intumescent material is VERSACHAR® resin, a thermoplastic intumescent layer available from FlameOFF Coatings, Inc., based in Raleigh, North Carolina. In an alternative example, the flame-retardant layer 146 may include an intumescent material impregnated into a fiberglass fabric. In yet another example, the flame-retardant layer 146 may include an intumescent material without any fabric or fibers (e.g., a layer of intumescent material only).

[0026] One or more of the layers of the ballistic panel 100 can be attached together using adhesive layers. For example, a first adhesive layer 150 can adhere the first layer of ballistic material 120 to the core layer 102, and a second adhesive layer 150 can adhere the second layer of ballistic material 122 to the core layer 102. Another adhesive layer 150 can be used to adhere the face sheets 130, 132 to the ballistic panel 100. Any suitable adhesive material can be used that provides a sufficient bond between the layers. For example, a urethane adhesive or an epoxy adhesive can be used.

[0027] Other embodiments of the ballistic panel of the present disclosure are contemplated. For example, instead of the cellular core layer previously described as core layer 102 shown in Figures 2, 4, and 5, the core layer may be another type of layer containing ballistic gel, such as a ballistic gel layer without cell walls configured with a plurality of cells 110. For example, the core layer may be a layer consisting solely of ballistic gel foam. Examples of suitable ballistic gel foam materials include those known in the art, such as the D3O® material described herein. Figure 6 shows a schematic cross-sectional view of one such embodiment of a ballistic panel using a core layer 102 containing ballistic gel foam without cell walls 108.

[0028] In yet another embodiment, the core layer 102 of the ballistic panel shown in FIG. 6 may be a laminate structure including multiple plies of ballistic material and one or more layers of ballistic gel. An example of such a laminate structure is shown in FIG. 7, which includes multiple sheets 170 of ballistic material and one or more layers 172 of ballistic gel disposed between the sheets 170 of ballistic material and bonded to the sheets by suitable means, such as an adhesive (not shown). The ballistic material may be, for example, a fabric made from woven para-aramid fibers, such as Kevlar (polyparaphenylene terephthalamide) fibers. In the core layer 102 of FIG. 7, the para-aramid fiber fabric may or may not be impregnated with a cured resin. The ballistic gel may be, for example, a ballistic gel foam, such as a layer of D3O material described herein. The laminate structure shown in FIG. 7 may be included as the core layer 102 in the ballistic panel 100 shown in FIG. 6.

[0029] The ballistic panel 100 shown in FIG. 6 also includes layers 120, 122 of ballistic-resistant material, face sheets 130, 132, and an adhesive layer 150 for adhering the layers together. The layers 120, 122 of ballistic-resistant material, face sheets 130, 132, and adhesive layer 150 may be the same as those described above with reference to FIG. 2. The ballistic panel 100 further includes cellular layers 180 and 182. The cellular layers 180, 182 include cell walls 108 that form cells 110. The cells 110 are the same as those described above with reference to FIG. 3, except that the cells 110 are filled with a gas, such as air, instead of ballistic gel. The cellular layers 180, 182 are bonded to adjacent layers using a suitable adhesive 150.

[0030] The ballistic panels of the present disclosure can be used in any desired application where ballistic protection is desired. Examples of such applications include ballistic protection for aircraft, aerospace vehicles, and other vehicles or structures used for military purposes. Other examples include ballistic door panels used between passenger cabins on commercial aircraft for anti-terrorism purposes, and other applications where a relatively lightweight means of ballistic protection is desired.

[0031] FIG. 8 shows an example of a bullet-resistant door 200 for an aircraft 202. The aircraft 202 includes a skin 205 that forms a fuselage. The interior of the aircraft 202 includes a flight deck wall 206 having a bullet-resistant door 200, such as a flight deck door. The flight deck wall 206 and the bullet-resistant door 200 separate a flight deck area (side) 212 from a passenger cabin area (side) 214. The bullet-resistant door 200 can restrict access to the flight deck side 212 from the passenger cabin side 214. The bullet-resistant door 200 can also be used as a door located elsewhere in the fuselage, if necessary. Typically, the bullet-resistant door 200 is configured to fit into a door frame in the flight deck wall 206. One side of the bullet-resistant door 200 includes a hinge 207 that engages with a hinge 208 on the door frame, allowing the bullet-resistant door 200 to be easily opened and closed. The bullet-resistant door 200 also includes a door latch or locking mechanism 209. The locking mechanism 209 engages with a jam lock mechanism (not shown) on the door frame to lock the bullet resistant door 200 in the closed position.

[0032] 9, the present disclosure also relates to a method for making a ballistic panel. The method includes providing a core layer having a first major surface and a second major surface. The core layer includes a ballistic gel. A first layer of ballistic material is attached to the first major surface of the core layer. A second layer of ballistic material is attached to the second major surface of the core layer. The core layer and the layer of ballistic material may be any of the layers described above.

[0033] The method may optionally include attaching additional layers to the ballistic panel. For example, the method may optionally include attaching a first face sheet to the first layer of ballistic-resistant material and attaching a second face sheet to the second layer of ballistic-resistant material. As another example, the method may optionally further include attaching one or more layers of para-aramid fibers woven into a fabric and impregnated with a flame retardant. As yet another example, the method may optionally further include attaching an intumescent layer, which may act as a flame retardant, to the first face sheet and / or the second face sheet. As another example, the method may optionally further include attaching a first cellular layer to the first layer of ballistic-resistant material before attaching the first face sheet and attaching a second cellular layer to the second layer of ballistic-resistant material before attaching the second face sheet. Both the first and second cellular layers include cell walls forming a plurality of cells, the plurality of cells being filled with a gas. A first face sheet can be attached to the first cellular layer and a second face sheet can be attached to the second cellular layer, similar to the example shown in Figure 6. Any of the face sheet layers, fabric-woven para-aramid fiber layers impregnated with flame retardant, intumescent layers, decorative layers, or cellular layers described herein can be used in the methods of the present disclosure.

[0034] The core layer 102 may be a cellular core layer manufactured by incorporating ballistic gel 112 into a plurality of cells 110 formed by cell walls 108, as shown in Figure 3. For example, the ballistic gel 112 acts as a liquid under slowly applied pressure and is embedded into the honeycomb core cells. The pressure to embed the ballistic gel 112 may be applied using gravity or other suitable techniques.

[0035] As discussed above, one or more of the layers of the ballistic panel 100 can be bonded together using an adhesive layer. For example, the method can include bonding the first layer of ballistic material 120 to the core layer 102 and the second layer of ballistic material 122 to the core layer 102 using an adhesive layer 150. It should be noted that other adhesive layers 150 can also be used to bond the face sheets 130, 132 to the ballistic panel 100. The bonding process can be performed using a hot bonding method, in which the adhesive layer 150 is heated and cured, for example, at one of the hot bonding temperatures described herein. Hot bonding is preferred because it saves processing time compared to cold bonding techniques, although cold bonding can also be used if desired. Both hot bonding and cold bonding techniques are generally well known in the art.

[0036] The foamable layer 140 can be attached to the face sheets 130, 132 by any suitable layering technique. Suitable layering techniques are well known in the art and can be selected by one of ordinary skill in the art. A primer (not shown) can be applied to the face sheets before attaching the foamable layer 140. The primer helps to ensure good adhesion between the foamable layer 140 and the face sheets.

[0037] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their testing measurements. Moreover, all ranges disclosed herein should be understood to include all subranges subsumed therein.

[0038] Furthermore, the present disclosure includes examples according to the following appendices.

[0039] Appendix 1. A core layer (102) having a first major surface (104) and a second major surface (106), the core layer (102) including a ballistic gel (112); a first layer (120) of ballistic resistant material disposed on the first major surface (104) of the core layer (102); a second layer (122) of ballistic material disposed on the second major surface (106) of the core layer (102).

[0040] Appendix 2. The bulletproof panel (100) of Appendix 1, wherein the core layer (102) is a cellular core layer including cell walls (108) configured to have a plurality of cells (110), and the bulletproof gel (112) is embedded in the plurality of cells (110).

[0041] Appendix 3. The ballistic panel (100) of Appendix 1 or 2, wherein the cell walls (108) comprise para-aramid fibers.

[0042] Appendix 4. The bulletproof panel (100) according to any one of appendices 1 to 3, wherein the bulletproof gel (112) is a non-Newtonian fluid having the property of increasing stiffness when impacted by a bullet.

[0043] Appendix 5. The ballistic panel (100) of any one of Appendixes 1 to 4, wherein the thickness of the core layer (102) is within the range of about 0.2 inches to about 5 inches.

[0044] Appendix 6. The ballistic panel (100) of any one of Appendixes 1 to 5, wherein the first layer of ballistic resistant material (120) and the second layer of ballistic resistant material (122) both comprise para-aramid fibers impregnated with a curable resin.

[0045] Appendix 7. The ballistic panel (100) of any one of Appendixes 1 to 6, wherein the thickness of each of the first layer of ballistic material (120) and the second layer of ballistic material (122) is within the range of about 0.1 inches to about 0.5 inches.

[0046] Appendix 8. The ballistic panel (100) of any one of Appendixes 1 to 7, further comprising a first adhesive layer (30) and a second adhesive layer (30), wherein the first adhesive layer (30) adheres the first layer of ballistic material (120) to the first major surface (104) of the core layer (102), and the second adhesive layer (30) adheres the second layer of ballistic material (122) to the second major surface (106) of the core layer (102).

[0047] Appendix 9. The ballistic panel (100) of any one of Appendixes 1 to 8, further comprising a first face sheet (130) attached to the first layer (120) of ballistic resistant material, and a second face sheet (132) attached to the second layer (122) of ballistic resistant material.

[0048] Clause 10. The ballistic panel (100) of Clause 9, wherein each of the first face sheet (130) and the second face sheet (132) comprises aluminum.

[0049] Clause 11. The ballistic panel (100) of Clause 9, wherein the thickness of each of the first face sheet (130) and the second face sheet (132) is within the range of about 0.005 inches to about 0.04 inches.

[0050] Clause 12. The ballistic panel (100) of clause 9, further comprising an intumescent layer (140) disposed on the first face sheet (130).

[0051] Clause 13. The ballistic panel (100) of clause 12, wherein the thickness of the intumescent layer (140) is in the range of about 0.001 inches to about 0.1 inches.

[0052] Appendix 14. The ballistic panel (100) of any one of Appendixes 1 to 13, further comprising a flame retardant layer (146) selected from: i) one or more layers of fabric comprising para-aramid fibers impregnated with a flame retardant; ii) a layer comprising glass fiber fabric impregnated with an intumescent material; and iii) a layer consisting solely of an intumescent material.

[0053] Appendix 15. The bulletproof panel (100) according to any one of appendices 1 to 14, further comprising a decorative layer (160) provided on the first layer (120) of bulletproof material.

[0054] Appendix 16. A ballistic panel (100) according to any one of Appendixes 1 to 15, comprising a first cellular layer adhered to the first layer (120) of ballistic-resistant material and a second cellular layer adhered to the second layer (122) of ballistic-resistant material, the first and second cellular layers both comprising cell walls (108) forming a plurality of cells (110), the plurality of cells (110) being filled with a gas.

[0055] Clause 17. The ballistic panel (100) of clause 16, wherein the core layer (102) is a laminated structure including multiple plies (120) of ballistic material and one or more layers of ballistic gel (112).

[0056] Clause 18. The ballistic panel (100) of Clause 16, wherein the ballistic gel (112) comprises a closed-cell polyurethane foam matrix and polyborodimethylsiloxane (PBDMS) dispersed in the closed-cell polyurethane foam matrix.

[0057] Appendix 19. A door for an aircraft (202) comprising a ballistic panel (100) according to any one of appendices 1 to 18.

[0058] Appendix 20. A method for making a ballistic panel (100), comprising: providing a core layer (102) having a first major surface (104) and a second major surface (106), wherein the core layer (102) comprises a ballistic gel (112); attaching a first layer (120) of ballistic resistant material to the first major surface (104) of the core layer (102); attaching a second layer (122) of ballistic resistant material to the second major surface (106) of the core layer (102).

[0059] Appendix 21. The method of Appendix 20, wherein the core layer (102) is a cellular core layer including cell walls (108) configured to have a plurality of cells (110), and the ballistic gel (112) is embedded in the plurality of cells (110).

[0060] Appendix 22. The method of any one of Appendixes 20 to 21, wherein the cell walls (108) comprise para-aramid fibers.

[0061] Appendix 23. The method of any one of Appendixes 20 to 22, wherein the ballistic gel (112) is a non-Newtonian fluid that has the property of increasing stiffness when impacted by a bullet.

[0062] Appendix 24. The method of any one of Appendixes 20-23, wherein the first layer of ballistic resistant material (120) and the second layer of ballistic resistant material (122) both comprise a fabric including para-aramid fibers impregnated with a curable resin.

[0063] Item 25. The method of any one of Items 20-24, further comprising one or more layers of fabric comprising para-aramid fibers impregnated with a flame retardant.

[0064] Appendix 26. The method according to any one of appendices 20 to 25, wherein the bulletproof panel (100) is produced by a hot bonding method.

[0065] Clause 27. The method of any of Clauses 20-26, further comprising attaching a first face sheet (130) to the first layer (120) of ballistic resistant material, and attaching a second face sheet (132) to the second layer (122) of ballistic resistant material.

[0066] Clause 28. The method of clause 27, further comprising attaching a foamable layer (140) to the first facesheet (130).

[0067] Clause 29. The method of Clause 27, further comprising attaching a first cellular layer to the first layer of ballistic resistant material (120) before attaching the first face sheet (130), and attaching a second cellular layer to the second layer of ballistic resistant material (122) before attaching the second face sheet (132), wherein the first cellular layer and the second cellular layer both comprise cell walls (108) forming a plurality of cells (110), the plurality of cells (110) being gas-filled.

[0068] While the present disclosure has been described using one or more embodiments, changes and / or modifications can be made to the described examples without departing from the spirit and scope of the appended claims. Furthermore, while certain features of the present disclosure may be disclosed in connection with only one of several embodiments, such features may also be combined with one or more features in other embodiments that may be desirable and advantageous for a given or particular function. Furthermore, various terms such as "comprises," "includes," "has," "having," and "comprises" may be used in the detailed description and claims, and these terms are intended to be inclusive and not to the exclusion of other elements. Furthermore, in the description and claims herein, the term "about" indicates that a stated value may be slightly modified, provided that such modifications do not render the process or structure incompatible with the intended purpose described herein. Finally, the term "exemplary" indicates that the description is used as an example, rather than an ideal.

[0069] Variations of the above-disclosed and other features and functions, or alternatives thereof, may be combined to construct many different systems or applications. Various substitutions, alterations, modifications, or improvements not presently contemplated may subsequently occur to those skilled in the art, which are intended to be within the scope of the following claims.

Claims

1. a core layer having a first major surface and a second major surface, the core layer including a ballistic gel; a first layer of ballistic material disposed on the first major surface of the core layer; a second layer of ballistic material disposed on the second major surface of the core layer; and a first cellular layer adhered to the first layer of ballistic resistant material; a second cellular layer adhered to the second layer of ballistic material, the first cellular layer and the second cellular layer both include cell walls forming a plurality of cells, the plurality of cells being filled with a gas; the core layer is a laminated structure including multiple plies of ballistic resistant material and one or more layers of ballistic gel; The ballistic gel comprises a closed-cell polyurethane foam matrix and polyborodimethylsiloxane (PBDMS) dispersed in the closed-cell polyurethane foam matrix.

2. 10. The ballistic panel of claim 1, wherein the cell walls comprise para-aramid fibers.

3. 3. A ballistic panel according to claim 1 or 2, wherein the ballistic gel is a non-Newtonian fluid having the property of increasing stiffness when impacted by a bullet.

4. 4. The ballistic panel of claim 1, wherein the first layer of ballistic resistant material and the second layer of ballistic resistant material both comprise para-aramid fibers impregnated with a curable resin.

5. 5. The ballistic panel of claim 1, further comprising a first adhesive layer and a second adhesive layer, the first adhesive layer adhering the first layer of ballistic material to the first major surface of the core layer, and the second adhesive layer adhering the second layer of ballistic material to the second major surface of the core layer.

6. A bulletproof panel as described in any one of claims 1 to 5, further comprising a first face sheet provided on the first cell type layer and a second face sheet provided on the second cell type layer.

7. An aircraft door comprising a ballistic panel according to any one of claims 1 to 6.

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