Bullet resistant protector

Abstract

A bullet resistant protector comprises a bullet resistant membrane arrangement (1), which bullet resistant membrane arrangement (1) comprises a layered stack of porous membranes (2). The bullet resistant protector can be used in a wearable article or in a vehicle, for example.

Description

[0001] Bullet resistant protector

[0002] Technical Field

[0003] The invention relates to a bullet resistant protector, to a bullet resistant wearable article and to a vehicle comprising such a bullet resistant protector, as well as to the use of a membrane arrangement as a bullet resistant protector.

[0004] Background Art

[0005] In WO2022 / 042855 Al, the inventor proposed a new separator arrangement for batteries and accumulators, specifically for electrically separating anode and cathode of such battery or accumulator. The separator arrangement comprises a thin, porous polymer separator in combination with a porous filter. The latter provides a protection against the increased bias of the thin separator towards short circuits .

[0006] Bullet proof or bullet resistant vests are known and are used by police officers, soldiers and security staff, for example. The purpose of such bullet resistant vest is to absorb the impact of a projectile of a gun fired onto the vest.

[0007] Vests of the art comprise woven Kevlar serving as bullet resistant protector means. The Kevlar layer typically is of at least 2.5 cm thickness and significantly contributes the overall weight of the vest of 13 to 15 kg. Both, considerable thickness and considerable weight reduce the comfort of wearing such bullet resistant vests.

[0008] Disclosure of the Invention Accordingly, there is a need for more comfortable bullet resistant protectors while at the same not waiving the bullet resistant characteristics of traditional protectors e.g. made from Kevlar.

[0009] According to an aspect the present invention, a bullet resistant protector is provided comprising a bullet resistant membrane arrangement. The membrane arrangement comprises a layered stack of porous or printed membranes .

[0010] Bullet resistance is considered a characteristic according to body armor performance standards. Most prominent amongst such standards are the US NIJ (National Institute of Justice ballistic and stab documents) , the UK HOSDB (Home Office Scientific Development Branch) , and the European VPAM (Association of Laboratories for Bullet Resistant Materials and Constructions) . Bullet resistance in the present context preferably is given as soon as the lowest class of one of the listed major standards is met, i.e. at least Type I of the US NJI, or HG1 of the UK HOSDB, or PM1 of the European VPAM.

[0011] The bullet resistant protector presently comprises or is represented by a bullet resistant membrane arrangement. The bullet resistant membrane arrangement comprises a multitude of membrane layers stacked on each other. Preferably each of the membrane layers is a porous layer or a layer comprising printed elements, of several micrometers of thickness and of a few grams of weight.

[0012] While a single membrane layer may not necessarily qualify as bullet resistant, a stack of a number of such porous membranes qualifies as bullet resistant, at least for one of the lowest bullet resistance classes of one of the above listed major standards, and preferably also for a multitude of higher classes of one or more of the above listed major standards. The bullet resistant protector may in one scenario be identical to the membrane arrangement, or in a different scenario, may comprise one or more elements, such as a Kevlar layer, in addition to the membrane arrangement . The membrane arrangement in turn comprises a stack of the porous or printed membranes , while layers with other characteri stics than the membranes described may also be added but are not considered to be part of the stack .

[0013] Whi le in the past , an individual membrane o f such kind was invented according to WO2022 / 042855 Al as a separator for a vehicle battery, the inventor tested a layered stack of such membrane layers as to bullet resistance characteristics . Surprisingly, it turned out , that such stack quali fies for at least the lowest classes of one o f the maj or standards , and, subj ect to the number of membrane layers , also for higher classes of the maj or standards .

[0014] The reason for this i s that the membrane is a porous membrane allowing air to migrate into and between the membrane layers . This air is considered as a buffer ready to absorb a good portion of the energy of a proj ectile received by the membrane arrangement . Hence , although the membrane arrangement at first glance looks vulnerable to impacts in view o f its pores and the layered arrangement o f a couple of only few microns thick membranes , the stacked membrane arrangement surpris ingly quali fies as bullet resistant protector . In view i f the thin, porous and light-weight membranes contributing to the membrane arrangement , the membrane arrangement is thinner and o f lower weight than existing Kevlar bullet resistant protectors for the same protection class . Its lower thickness and its lower weight , in turn, each and in combination enhances the comfort of wearing such body armor and facilitates its wearer to move easier and faster, which in particular is relevant to the above listed group of users such as police o f ficers , soldiers and security personnel .

[0015] Pre ferably, the membranes of the stack are arranged on top of each other, wherein each additional membrane increases the thickness / height o f the stack, while at the same time adds protection. Preferably, the membranes of the layered stack are attached to each other at one or more, and preferably at all edges. Accordingly, the membrane arrangement can be handled as a single piece after assembly. The attachment preferably is achieved by an adhesive, preferably a synthetic resin, preferably an epoxy resin, preferably a methylmethacrylat (MMA) adhesive, preferably a 2K-methylmethacrylat (MMA) adhesive, preferably one of Technicoil ® 9403, Technicoil ® 9413, and Technicoil ® 8053. It is preferred that the membranes are not attached or fixed to each other than at the limited areas represented by the one or more or all edges. Accordingly, preferably an area of less than 20%, preferably less than 10% of the overall membrane area is covered by an adhesive, in which area the pores are typically sealed by way of the adhesive. In the remaining area, the pores of the membrane remain open such that air can fill the pores, migrate from layer to layer, and reside between adjacent membranes.

[0016] I.e., other than at the one or more edges, the membranes of the layered stack rest against each other absent a fixing means. In such membrane arrangement, air may migrate from the outside of the membrane arrangement through the pores of the outer membranes into the interior of the membrane arrangement, and in between adjacent membranes. In such way, the membrane arrangement forms an air cushion which contributes to absorbing kinetic energy from a projectile or other element fired at the membrane arrangement.

[0017] Each membrane of the stack preferably is made from a synthetic material, preferably from one of PE (polyethylene) , PET (polyethylene terephthalate) , in particular a Hostaphan foil, PETP (polyethylene terephthalate polyester) , PP (polypropylene) or OPP (oriented polypropylene) . Such material withstands heat of at least 130° C, preferably of at least 175 °C. Preferably, the separator shows a tension resistance of at least 1 Nm. In absolute numbers, it is preferred that the porosity of the membranes is 50% or more, preferably 60% or more, preferably 70% or more, preferably between 10% and 90%. Porosity as such is defined as a ratio of voids in a material accessible from its surface over a total volume of the material.

[0018] As to the numbers of pores in the membranes, also referred to as density, it is preferred that the membrane comprises 50 pores or more per cm2, preferably 500 pores or more per cm2, preferably 1000 pores or more per cm2. In particular, the membranes comprise 2000 or more pores per cm2. Preferably, the membranes comprise not more than 8000 pores per cm2. In a preferred embodiment, in particular for bullet resistant wearable articles such as vests, the membranes comprise between 50 and 8000 pores per cm2. These numbers are preferred in achieving the desired porosities as laid out above.

[0019] Preferably, the pores of a membrane are of uniform size. Uniform in this context shall be defined that at least 95% of the pores are within 10% of a given diameter. Preferably a diameter of the pores in the membrane is between 5 pm and 95 pm. In particular, the diameter of the pores in the membrane is less than 25 pm, and hence preferably between 5 pm and 25 pm. Preferably, the pores across the membranes are of uniform size.

[0020] Preferably, the pores are not only of equal diameter / size, but are also arranged equidistant from each other, e.g. in rows and columns.

[0021] Preferably, the membrane is a flat element with a plane extension of length and width, each exceeding its height / thickness by far. Preferably, each membrane has a thickness of 10 pm or less, preferably a thickness between 6 pm and 8 pm.

[0022] In one embodiment, the membrane is manufactured by the following method: A printing technique is applied for printing elements such as circle-shaped dots onto a foil which later shall serve as membrane. Other shapes of the elements are possible. In a further step, the printed foil is irradiated such that the printed elements melt and generate holes in the foil, which holes act as pores of the membrane. The ink the elements are printed with preferably comprises a material inflammable in response to the radiation, such that holes with a defined diameter are generated. Preferably, a laser or laser bar is used for the irradiation. Preferably, the wavelength emitted by the laser or laser bar is in the infrared range. Preferably, the holes are only generated at locations where the irradiation meets the ink, but not outside. Hence, it is preferred that the irradiation triggers a thermodynamic reaction in the printed ink, but only there, not outside the ink dots / elements. This effect can be achieved or enhanced when adding metal particles to the ink absorbing the infrared radiation. Hence, even if a laser bar irradiates the entire foil, only the locations wetted by ink transform into holes / pores. Preferably, the foil is moved relative to the laser bar. In case the resulting membrane shall not comprise pores but printed elements only, the process does not comprise the irradiation step.

[0023] The device for printing the elements onto the foil preferably is a cylinder with a pattern of indentations, or micron sized recessed dots, on its outer surface. The cylinder preferably is made from steel and is coated with a layer of copper, e.g. by electroplating, e.g. of at least 200 pm. The indentations preferably are generated in the layer of copper by way of a laser. In order to generate an indentation diameter and an indentation density resulting in the mentioned pore diameter and density ranges, it is preferred that a resolution of the laser is in the range of 2 pm to 12 pm. Hence, the cylinder can be considered to be engraved. A depth of the indentations preferably is between 5 pm and 90 pm. The pattern of indentations in the cylinder is used to transfer ink at defined positions onto the foil or substrate. For this purpose, the cylinder is wetted by the ink, which ink preferably is a fluid ink based on water. Accordingly, the indentations are filled by the ink and the ink remains in the indentations due to surface tension. The ink wetted cylinder then is rolled over the foil such that the ink is transferred from the various indentations onto the foil and an ink pattern is generated on the foil that corresponds to the pattern of indentation on the cylinder. The result is a foil with ink printed elements, such as dots, corresponding to the pattern on the cylinder. The resulting membrane is a foil with pore sizes in the above range, and a hole density in the above range.

[0024] In case the resulting membrane shall not comprise pores but printed elements only, the printed elements shall be considered to replace the pores in the foregoing and the following. As a result, e.g. the density of such elements and elements per cm2replace the previous measures porosity and pores per cm2, respectively.

[0025] In manufacturing the membrane arrangement, it is preferred that the membrane material, e.g. the prepared foil manufactured by the process described above, is provided in form of a tape on a roll. Preferably, the tape is controlled to be unwound from the roll, e.g. by the aid of one or more electric motors for rotating the roll, and / or by guiding means for guiding the unwound portions to the destination position. In a next step, the tape is cut e.g. by a cutting tool, such as blade, into an individual membrane of the desired, e.g. rectangular shape. In one embodiment, the membranes cut from the tape are collected at least until the required number of membranes are cut for building the membrane arrangement. In a next step, the membranes are glued to each other at their edges. In a different embodiment, the cutting tool is arranged such that the membrane cut from the tape already is located on top of a stack already started to be built, and is adhered to such stack. Preferably, such manufacture is implemented in an automated manner, comprising an electronic control unit configured to control the unwinding of the membrane material, the cutting of the membranes from the tape, the positioning of the cut membranes if needed, and the gluing of the cut membrane to an existing membrane / stack.

[0026] The membrane arrangement preferably comprises a number of porous membranes of 50 or more, preferably 100 or more, preferably 1000 or more. As an upper limit, the membrane arrangement may preferably comprise 1500 or less. In a preferred embodiment, the number of porous membranes in the layered stack is between 50 and 1500.

[0027] The number of the membranes in the layered stack at least co-defines the class of protection that is achieved by such bullet resistant protector. The more layers are provided in the membrane arrangement, the better protection, i.e. the higher protection class can be achieved, at the cost of thickness and weight of the membrane arrangement. However, the present membrane arrangement reaches the same protection class with a reduced thickness as well as a reduced weight compared to the known bullet resistant protector made from Kevlar.

[0028] Preferably, the layered stack of the membrane arrangement has a thickness of 20 mm or less, more preferably of 18 mm or less, and preferably between 16 mm and 18 mm. By such thickness of the membrane arrangement, and the corresponding number of membrane layers contributing to the membrane arrangement, e.g. protection classes PM1 up to PM10 of the European VPAM scale can be fulfilled.

[0029] The thickness of the membrane arrangement, however, can even be smaller, e.g. 16 mm or less, however, possibly at the cost of the protection class achieved .

[0030] In a preferred embodiment of the present invention, the protector comprises at least one layer comprising aromatic polyamide fibers, preferably Kevlar fi- bers . This may enhance the bullet resistance even further. This layer preferably has a thickness between 0.5 mm and 3 mm, preferably between 1 mm and 2 mm, and this layer preferably is attached to the membrane arrangement. In a different embodiment, the membrane arrangement is sandwiched between two layers comprising aromatic polyamide fibers. In another embodiment, wherein the bullet resistant membrane arrangement comprises multiple membrane arrangements and multiple layers comprising aromatic polyamide fibers, the membrane arrangements and the layers comprising aromatic polyamide fibers are arranged alternating .

[0031] Such protector may have a thickness of more than 30 mm, and / or less than 60 mm, in case the protector shall protect from even higher impact energies. According to another aspect of the present invention, a bullet resistant wearable article is provided, comprising a fabric and a bullet resistant protector according to any of the above embodiments. The bullet resistant protector is one or more of attached to, integrated in, deposited into a pocket of, or otherwise combined with the fabric. While the fabric serves the wearability, the bullet resistance material serves protecting the wearer.

[0032] The wearable article preferably is a garment, including one or more of a vest, a jacket, trousers, a helmet, gloves, etc. Accordingly, the bullet resistance wearable article may also be understood as body armor. In particular, in case of a vest of a jacket its weight is 12 kg or less, preferably 10 kg or less. According to another aspect of the present invention, a bullet resistant vehicle is provided, comprising vehicle parts, and a bullet resistant protector according to any of the above embodiments. The bullet resistant protector is one or more of attached to, integrated in, or otherwise combined with at least one part of the vehicle, or even may represent a part of the vehi- cle on its own. Preferably, the bullet resistant protector is used as a part of a or all windows of the car. In this respect, the bullet resistance vehicle preferably is attached to a glass panel of the car window, and / or is sandwiched in between two glass layers, which one or more glass layers may also be manufactured from bullet proof glass. The integration of the protector into a glass panel is not limited to vehicle applications. Such glass panels may also be installed in buildings etc. In a different application, the protector may be embodied as shield, e.g. for police officers, etc.

[0033] According to a further aspect of the present invention, the usage of a membrane arrangement is provided, the membrane arrangement comprising a layered stack of porous membranes as a bullet resistant protector, in particular which membrane arrangement is used in a wearable article or in a vehicle or in a building. It is explicitly stated that all embodiments disclosed in connection with one aspect of the present invention shall also be considered disclosed in connection with the other aspects of the present invention.

[0034] Brief Description of the Drawings

[0035] The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description of embodiments thereof. Such description makes reference to the annexed drawings, wherein:

[0036] Fig. 1 illustrates a membrane arrangement in a perspective view, according to an embodiment of the present invention; Figs. 2 and 3 illustrate a schematic top view on a membrane as used in a membrane arrangement, e.g. according to Fig. 1, according to an embodiment of the present invention;

[0037] Fig. 4 schematically illustrates a perspective view of a bullet resistant wearable article, according to an embodiment of the present invention;

[0038] Fig. 5 illustrates different bullet resistant protectors in a side or cut view, according to embodiments of the present invention; and

[0039] Fig. 6 illustrates an image of a bullet resistant protector according to an embodiment of the present invention, after being fired at.

[0040] Modes for Carrying Out the Invention

[0041] Fig. 1 illustrates a bullet resistant membrane arrangement 1 in a perspective view, usable as a bullet resistant protector in various applications, according to embodiments of the present invention. The membrane arrangement 1 comprises multiple porous membranes 2 arranged as layered stack, i.e. in planes parallel to each other. In the example, three membranes 2 are illustrated in the front, two in the back. Preferably, there are many more membranes arranged in between as indicated by the dots, such that the overall number of membranes arranged in the membrane arrangement is between 50 and 1500.

[0042] Each membrane 2 has a thickness tl, e.g. between 6 pm and 8 pm. The overall membrane arrangement 1 has a thickness t2, which at minimum corresponds to the number of membranes n*tl. Each membrane 2 has a horizontal extension in x- and y-direction exceeding its thickness tl by far. Accordingly, the membrane layers 2 are arranged on top of each other, and, preferably are attached to each other, e.g. by means of an adhesive, such as a synthetic resin. Preferably, the area covered by the adhesive, and, hence, the area used for the attachment is denoted as Al in Figure 1. Accordingly, the membranes 2 are attached to each other at their edges. The majority of the membrane's surface A2 is not covered by the adhesive. The membranes 2 may rest against each other at surfaces A2. There may even be an air gap between two adjacent membrane's surfaces A2. Generally, the shape of the membranes 2 and, hence, the shape of the membrane arrangement 1 is rectangular in x and y-direction in the embodiment of Fig. 1. However, other shapes such as a circular shape may also be possible.

[0043] Figures 2 and 3 illustrate enlarged schematic portions of top views on individual membranes 2, such as used in membrane arrangements according to embodiments of the present invention. As can be seen from Figure 2, the membrane 2 is a foil having pores 21 of diameter dl . The pores 21 are of uniform size, and in particular of uniform diameter dl . The pores 21 are also arranged equidistant from each other in a grid, such that a distance xl between rows of pores 21 is the same across all rows, and a distance x2 between columns of pores 21 is the same across all columns. In particular xl = x2 , such that the pores 21 are arranged in a uniform rectangular pattern. In contrast, and as can be seen from Figure

[0044] 3, the membrane 2 may alternatively have pores 21 of non- uniform diameter dl and d2. Hence, one of the pores 21 may show diameter d3, while another pore 21 may show a diameter different from d2. Neither are the pores 21 of uniform size, nor are they arranged in a regular pattern.

[0045] Fig. 4 schematically illustrates a perspective view of a bullet resistant wearable article, according to an embodiment of the present invention. The bullet resistance wearable article presently is a vest with a front portion 31 and a back portion 32, connected via straps 33. The vest is meant to be slipped over the head of a user, such that the straps rest on the shoulders of the user. The front portion 31 covers the front body portion of the user, the back portion 32 covers the back of the user during use. The vest preferably is a garment made from fabrics.

[0046] The front portion 31 of the vest, and preferably also the back portion 32 - although not visible - comprises a pocket 311 formed by the fabric. The pocket 311 may be accessible via an opening which presently is closed by a hook-and-loop-fastener indicated by 312. A membrane arrangement 1, such as e.g. shown in Fig. 1, is arranged in the pocket 311 of the fabric, and, accordingly, serves as a bullet resistant protector for the user wearing the vest, in particular against projectiles. The membrane arrangement 1 can simply be inserted into the pocket 311 absent additional fixing means. However, the membrane arrangement may also additionally be fixed within the pocket 311, e.g. by means of straps and / or hook-and-loop-f asteners .

[0047] Instead of a vest shaped fabric, a jacket shaped fabric may be equipped with such a bullet resistant protector in form of a membrane arrangement.

[0048] In general, in the context of bullet resistant wearable articles, the fabric not necessarily implied a natural material. Synthetic materials shall also be encompassed.

[0049] Fig. 5 illustrates different bullet resistant protectors in side or cut view, according to embodiments of the present invention. Diagram 5a) illustrates a bullet resistant protector comprising a membrane arrangement 1 absent any layer of different material. The membrane arrangement 1 has a thickness ti of e.g. 18 mm or 20 mm.

[0050] Diagram 5b) illustrates a bullet resistant protector comprising again a single membrane arrangement 1. This membrane arrangement 1 again has a thickness ti of e.g. 12 mm that is sandwiched between two layers 4 comprising aromatic polyamide fibers, preferably Kevlar fibers, also referred to as Kevlar layers 4. Each Kevlar layer 4 has a thickness t4 of e.g. 2 mm, such that the overall thickness of the bullet resistant protector amounts to 16 mm.

[0051] Diagram 5c) illustrates a bullet resistant protector comprising two membrane arrangements 1, each with a thickness ti of e.g. 6.5 mm. Three Kevlar layers 4 are provided. Each membrane arrangement 1 is sandwiched between two Kevlar layers 4. Each Kevlar layer 4 has a thickness t4 of e.g. 1 mm. The overall thickness of the bullet resistant protector amounts to 16 mm.

[0052] Diagrams 5d) and 5e) illustrate bullet resistant protectors with an overall thickness of e.g. 58 mm that protects for higher caliber projectiles. The protector according to diagram 5e) comprises a single membrane arrangement 1. This membrane arrangement 1 has a thickness ti of e.g. 54 mm that is sandwiched between two Kevlar layers 4 of a thickness t4 of 2 mm each. The protector according to diagram 5d) instead comprises four membrane arrangements 1 of a thickness of 12 mm each, and five Kevlar layers 4 with a thickness t4 of 2 mm each.

[0053] Fig. 6 illustrates an image of a bullet resistant protector according to an embodiment of the present invention, with a thickness of 16 mm after being fired at with a projectile of caliber 9 x 19 mm. As can be derived from the image, there is no outlet port from any of the proj ectiles .While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims .

Claims

Claims1. Bullet resistant protector, comprising a bullet resistant membrane arrangement (1) , which bullet resistant membrane arrangement (1) comprises a layered stack of porous or printed membranes (2) .

2. Bullet resistant protector according to claim 1, wherein the membranes (2) are made of poly- propylene .

3. Bullet resistant protector according to claim 1 or claim 2, wherein the membrane porosity is 50% or more, preferably wherein the membrane porosity is 60% or more, preferably wherein the membrane porosity is 70% or more, preferably wherein the membrane porosity is between 10% and 90%.

4. Bullet resistant protector according to any of the preceding claims, wherein the membranes (2) comprise 50 or more pores (21) per cm2, preferably 500 or more pores (21) per cm2, preferably 100 or more pores (21) per cm2, preferably 1000 or more pores (21) per cm2, preferably not more than 8000 pores (21) per cm2, preferably between 50 and 8000 pores (21) per cm2.

5. Bullet resistant protector according to any of the preceding claims, wherein a diameter (dl) of the pores (21) of each membrane (2) is between 5 pm and 95 pm, preferablywherein a diameter (dl) of the pores (21) of each membrane (2) is less than 25 pm, preferably between 5 pm and 25 pm.

6. Bullet resistant protector according to any of the preceding claims, wherein a thickness (tl) of each membrane (2) is less than 10 pm, preferably wherein a thickness (tl) of each membrane (2) is between 6 pm and 8 pm.

7. Bullet resistant protector according to any of the preceding claims, wherein a number of porous membranes (2) in the layered stack is 50 or more, preferably wherein a number of porous membranes (2) in the layered stack is 100 or more, preferably wherein a number of porous membranes (2) in the layered stack is 1000 or more, preferably wherein a number of porous membranes (2) in the layered stack is 1500 or less, preferably wherein a number of porous membranes (2) in the layered stack is between 50 and 1500.

8. Bullet resistant protector according to any of the preceding claims, , wherein the layered stack of the membrane arrangement (1) has a thickness (t2) of 60 mm or less, preferably wherein the layered stack of the membrane arrangement (1) has a thickness (t2) of 20 mm or less, preferably wherein the layered stack of the membrane arrangement (1) has a thickness (t2) of 18 mm or less, preferably wherein the layered stack of the membrane arrangement (1) has a thickness (t2) of 16 mm or less, preferably wherein the layered stack of the membrane arrangement (1) has a thickness (t2) between 16 mm and 18 mm .

9. Bullet resistant protector according to any of the preceding claims,wherein the membranes (2) of the layered stack are attached to each other at one or more, preferably at all edges, preferably by an adhesive, preferably wherein the adhesive is made from synthetic resin, preferably wherein other than at the one or more edges the membranes (2) of the layered stack are not mounted to each other, preferably wherein other than at the one or more edges the membranes (2) of the layered stack rest against each other absent a fixing means.

10. Bullet resistant protector according to any of the preceding claims, comprising at least one layer comprising aromatic polyamide fibers, preferably Kevlar fibers, preferably wherein the layer comprising aromatic polyamide fibers has a thickness between 0.5 mm and 3 mm, preferably between 1 mm and 2 mm, preferably wherein the at least one layer comprising aromatic polyamide fibers is attached to the membrane arrangement, preferably wherein the membrane arrangement is sandwiched between two layers comprising aromatic polyamide fibers, preferably comprising multiple membrane arrangements (1) and multiple layers comprising aromatic polyamide fibers, wherein the membrane arrangements and the layers comprising aromatic polyamide fibers are arranged alternating.

11. Bullet resistant protector according to any of the preceding claims, wherein the printed membranes (2) comprise elements printed on the membranes (2) , preferably wherein the printed membranes (2) comprise 50 or more printed elements per cm2, preferably 500 or more printed elements per cm2, preferably 1000 or more printed elements per cm2, preferably 2000 or moreprinted elements per cm2, preferably not more than 8000 printed elements per cm2, preferably between 50 and 8000 printed elements per cm2.

12. Bullet resistant wearable article, comprising a fabric ( 3 ) , and a bullet resistant protector according to any of the preceding claims, one or more of attached to, integrated in, deposited into a pocket of, or otherwise combined with the fabric, preferably wherein the wearable article is a vest or a jacket.

13. Bullet resistant wearable article according to claim 12, wherein a weight of the vest or jacket is 12 kg or less, preferably wherein a weight of the vest or jacket is 10 kg or less.

14. Bullet resistant vehicle, comprising vehicle parts, and a bullet resistant protector according to any of the preceding claims 1 to 11, one or more of attached to, integrated in, or otherwise combined with at least one part of the vehicle, preferably wherein the at least one vehicle part is a window of the car, preferably wherein the bullet resistant protector is attached to a glass panel of the car window.

15. Use of a membrane arrangement (1) comprises a layered stack of porous membranes (2) as a bullet resistant protector, in particular in a wearable article or in a vehicle.

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