EP3837487B1 - Multilayer ballistic protection panel - Google Patents

Description

Technical area

The present invention belongs to the technical field of materials for ballistic protection and reinforcement of structures in the face of various threats with high kinetic energy, impacting on a very small surface.

It relates more particularly to a compact panel comprising a superposition of layers of fabric woven from twisted polyester yarns, between which are interposed alternately layers (films) of thermoplastic adhesive based on polyethylene which ensure the cohesion of the assembly. , thanks to an interpenetration, at the time of its melting (melting point), by increasing the pressure of the press in a progressive form, of the thermoplastic adhesive between the meshes of the layers of polyester fabrics.

The panel according to the invention can be advantageously used for individual ballistic protection purposes, in particular in anti-bullet vests and EOD outfits (also reducing trauma "Deformation") or bulletproof accessories, but also collective in fixed or mobile installations , in particular for civil or military vehicles, or elements of construction or furniture.

Prior art

Nowadays, there are many technical solutions for individual or collective ballistic protection, such as the solution presented in the patent document WO0042246 A .

These generally use high-tech materials and are very expensive to obtain a high level of performance and lightness.

These materials are mainly made from mineral or synthetic fibers with very high mechanical performance and in particular from type S glass fibers, Para-aramid/Meta-aramid fibers or very high molar mass polyethylene fibers (UHMPE or UHMWPE for "Ultra High Molecular Weight Polyethylene" in English).

Materials made from glass fibers offer limited mechanical performance and ballistic protection compared to those obtained using specific synthetic fibers. They are therefore used for relatively small applications.

Those obtained from polyethylene fibers of very high molar mass, such as the SPECTRA ^™ fibers marketed by the company Honeywell or DYNEEMA ^™ marketed by the company DSM, are extremely expensive due to the very high price of the raw material and the difficult control of the manufacturing processes. They are therefore reserved for limited applications with high added value and for applications in which lightness is vital, such as for example in fixed-wing or rotary aircraft.

As a result, materials made from para-aramid and meta-aramid fibers, such as, for example, KEVLAR ^™ marketed by the Dupont company or TWARON ^™ from the Teijin company, are currently the most widely used to produce materials for ballistic protection intended, among other things, for protective clothing (bulletproof vests and jackets) or for the armoring of civilian or military vehicles.

However, even if their cost price is a little lower than that of materials based on polyethylene of very high molar mass, they remain expensive and the purchase of large surface panels, for example for the shielding of a military vehicle, is very expensive. Added to this are often very long lead times for obtaining such fibres.

Moreover, even if materials based on aramid fibers are technically efficient, they have many disadvantages.

Indeed, they are very sensitive to environmental conditions (UV, humidity, rot and to aging in general), which quickly compromises their mechanical properties and their efficiency. They therefore have a very low durability which requires frequent replacement, even if binding specific protective coatings (encapsulations) are used.

To guarantee the effectiveness of ballistic protection, it is thus recommended for military operational vehicles to replace the interior coating of military vehicles every year, when it is made with this type of material. Due to the high price of these materials, such a replacement, with the immobilization of the vehicle, represents a particularly high financial cost over the entire life of these vehicles.

In addition, due to the use of thermosetting synthetic raw materials, these materials are neither repairable nor recyclable.

In addition, these materials, including phenolic or epoxy resins, release very toxic compounds when burned.

For all these reasons, the current technical solutions are not satisfactory and a new solution is long overdue.

Disclosure of Invention

The object of the invention is to overcome the drawbacks of these materials of the prior art and to provide a ballistic protection material that is both effective and also economical.

For this, the invention teaches in claim 1 a multilayer ballistic protection panel comprising a superposition of layers of fabric in woven threads, the weaving leaving free through interstices between the threads in each layer of fabric, and layers of adhesive which are interposed alternately between the layers of fabric and which ensure the overall cohesion of the panel.

According to the invention, the fabric layers of woven yarns comprise layers of fabric woven of twisted polyester yarns, and the adhesive layers are layers of a thermoplastic material based on polyethylene.

In addition, the adhesive layers are layers of a thermoplastic material based on polyethylene, advantageously, based on polyethylene LLDPE - LDPE - HDPE.

In addition, the thermoplastic material passes through the interstices of the layers of fabric and connects the layers of adhesive with each other, thus ensuring the overall cohesion of the panel.

According to one embodiment, the multilayer ballistic protection panel is a compact laminated panel produced by hot pressing under high pressure, to circulate the molten adhesive between each mesh of the layers of fabric.

As the PE does not stick with anything, then we stick it with itself using the principle of thermofusion to thus stick the layers of fabric.

Alternatively, the fabric of the fabric layers woven with twisted polyester yarns can be woven in a flat or basket weave pattern.

According to one embodiment, the polyester yarns used are twisted Z or S, more preferably twisted Z, with from 40 to 80 twists per meter of yarn and preferably about 60 twists per meter of yarn.

By definition, twisted Z yarns are twisted clockwise and twisted S yarns are twisted counterclockwise. Twisted yarns Z are therefore twisted in the same direction as the rotating direction of the terrestrial projectiles, which enables the filaments of the yarn to advantageously retain better cohesion during an impact.

According to one embodiment, the polyester yarns used have a resistance of between 75 N and 110 N and preferably between 101.5 N - 103.9 N.

According to one embodiment, the polyester yarns used have a elongation between 8 and 25%, and preferably between 12-14%.

According to one embodiment, the polyester yarns used have a denier of between 800 and 4000 den, preferably between 1000 and 3000 den and preferably close to 1000 den or 1100 dtex.

According to one embodiment, the multilayer ballistic protection panel comprises between 5 and 120 layers of fabric woven with twisted polyester yarns, preferably twisted Z.

According to one embodiment relating to a splinter guard behind a steel plate, made with Z-twisted polyester yarns with a count equal to 1000 deniers, the multilayer panel comprises between 40 and 50 layers of fabric, and preferably 45 layers of fabric, woven with twisted polyester yarns, preferably twisted Z yarns, with a count equal to 1000 den or 1100 dtex.

According to another variant produced with twisted polyester yarns with a count equal to 3000 denier, the multilayer panel comprises between 15 and 22 layers of fabric, and preferably 18 layers of fabric, woven with twisted polyester yarns, preferably twisted Z , of fineness equal to 3000 den.

According to one embodiment, the fabric of the fabric layers is woven with a density, in number of warp threads per number of weft threads per 0.5 cm ² of fabric, of between 5x5 and 8x8 and preferably close to 7x7 for twisted polyester yarns, preferably twisted Z yarns, with a count equal to 1000 den or 1100 dtex.

According to another embodiment, the fabric of the fabric layers is woven, for example in flat braided weaving (Braided plain), with a density, in number of warp threads per number of weft threads for 0.5 cm ² of fabric, between 3.35x3.35- and 5x5, and preferably close to 4.53x4.53 for twisted polyester yarns, preferably twisted Z yarns, with a count equal to 3000 den. Such a yarn corresponds for example to three yarns of 1000 den each, twisted Z to form a single yarn.

The invention also teaches in claim 13 the use of such a multilayer ballistic protection panel for producing an interior or exterior covering of a vehicle, a covering or a ballistic protection accessory or a door, wall or partition veneer.

By way of example, such a multilayer ballistic protection panel can be used for the production of a passenger compartment wall, hood panel, underside of the vehicle, wheel arch, protective clothing of the vest type or bulletproof vest, complete demining suit, a ballistic protection accessory such as a helmet, shield, or a door or wall covering or of a partition of the door or armored partition of a building, of a cabin, of an armored enclosure, or even of a piece of furniture of the seat or office type.

The invention further teaches in claim 14 an armored composite panel comprising an armor wall and a ballistic protection coating, and whose ballistic protection coating is a multilayer ballistic protection panel, as presented above.

According to the embodiments, the shielding wall of this composite panel can be steel plate, aluminum plate, aluminum foam plate, titanium plate, fiberglass plate (FPR) , a glass or glass/ceramic plate, a polycarbonate plate, a multilayer plate of aramid fibers, a multilayer UHMWPE plate, a monolithic ceramic plate or an assembly of ceramic plates or modules or an assembly of perforated metal plates.

According to one embodiment of the composite panel, the multilayer ballistic protection panel is assembled against the shielding wall by gluing or mechanical fixing.

Depending on the applications envisaged, this armored composite panel can be a wall element of a vehicle, a building panel, a door, a wall or a partition, part of a piece of furniture, a wall of a seat, or an item of clothing, helmet or ballistic shield.

For example, a multi-layer panel can be placed inside any type of door during its manufacture depending on the level of protection required.

It is possible to use an existing door, or even a door made of PVC material, by fixing the multilayer panel to it with a decorative motif inlaid on one side, either by gluing, or by means of another mechanical fixing system. discreet and thus obtain bulletproof protection. In addition, a saving in costs and in installation time is obtained.

• Réaliser ou fournir des couches de tissu tissé en fils de polyester torsadés et des couches d'adhésif en matériau thermoplastique à base de polyéthylène,
• Superposer en alternance les couches de tissu et les couches d'adhésif,
• Placer la superposition ou la réaliser directement sur une plaque d'une presse de thermo-lamination de type Laminé à Haute Pression (HPL),
• Fermer la presse et augmenter la température et augmenter la pression sur la superposition jusqu'à une valeur de pression suffisante pour permettre une bonne diffusion et répartition de la chaleur à l'intérieur de la presse de manière à faire fondre le matériau thermoplastique des couches d'adhésif, et à compacter la superposition pour provoquer le passage du matériau thermoplastique fondu à travers les interstices des couches de tissu jusqu'à mettre en contact les couches d'adhésif adjacentes,
• Ensuite initier le cycle de refroidissement de la presse, sans ouvrir la presse et en maintenant la pression maximale exercée sur la superposition, pour provoquer la solidification du matériau thermoplastique, assurant ainsi la cohésion de la superposition sous la forme d'un panneau multicouche compact,
• Ouvrir la presse et en sortir le panneau multicouche obtenu.

Finally, the invention teaches in claim 18 a method of manufacturing such a multilayer ballistic protection panel. This process includes the following steps:

• Produce or supply layers of woven fabric in twisted polyester yarns and layers of adhesive in thermoplastic material based on polyethylene,
• Alternately superimpose the layers of fabric and the layers of adhesive,
• Place the overlay or make it directly on a plate of a press High Pressure Laminate (HPL) type thermo-lamination,
• Close the press and increase the temperature and increase the pressure on the overlay to a pressure value sufficient to allow good diffusion and distribution of the heat inside the press so as to melt the thermoplastic material of the layers of adhesive, and compacting the superposition to cause the passage of the molten thermoplastic material through the interstices of the layers of fabric until the adjacent layers of adhesive come into contact,
• Then initiate the cooling cycle of the press, without opening the press and maintaining the maximum pressure exerted on the overlay, to cause the solidification of the thermoplastic material, thus ensuring the cohesion of the overlay in the form of a compact multilayer panel,
• Open the press and take out the resulting multilayer panel.

According to one embodiment of this method, during the heating phase under pressure, it is possible to increase, for example on this type of HPL press, the temperature to a value between 135° C. and 165° C. and preferably between 135 and 154° C. at the heart of the multilayer panel and increase the pressure to a value of between 90 and 200 bars (kg/cm ² ) and preferably to a value of 110 bars (kg/cm ² ).

According to one embodiment of the method, during the cooling phase, the temperature can be reduced to a value between 50 and 70° C. and preferably between 60 and 65° C., before opening the press to extract the multilayer panels.

Such a temperature makes it possible to consider that the adhesive is solidified and advantageously makes it possible to reduce the time during which the multilayer panels are inside the press.

The multilayer panel according to the invention is made from readily available high-yield raw materials. With a cost price substantially divided by four compared to those of the prior art made from aramid fibers and UHMWPE. It is therefore much more economical.

In addition, it is much less sensitive to environmental conditions, is not or very little sensitive to UV, humidity or ambient temperature. It thus has a long lifespan, much greater than that of aramid fiber panels, and for example greater than the lifespan of a vehicle in which it could be installed. The savings made over the lifetime of a vehicle are therefore considerable.

In addition, the adhesive material used being thermoplastic, the multilayer panel according to the invention can easily be recovered to be repaired, modified or improved. The multilayer panels can, if necessary, be repaired by hot pressing after having removed projectiles and fragments of all kinds, or be improved by adding additional layers of polyester fabric, or even be connected by pressing together several panels for example of smaller thickness in order to obtain a more resistant panel.

In addition, the fibers are impermeable, but not at all breathable, and the adhesives used to form the panel according to the invention are recyclable and much less toxic in the event of combustion than the aramid panels.

On the other hand, the panels according to the invention can be easily implemented industrially, for example by forming, thermal or mechanical cutting with conventional mechanical means, which can be more difficult to achieve on materials using aramid fibers.

The multilayer panel according to the invention therefore has many advantages over those of the prior art for comparable or even improved efficiency.

Indeed, the multilayer panels compacted at very high pressure according to the invention are mechanically very resistant and have particularly interesting ballistic properties which allow them to advantageously replace panels made of aramid fibers, glass fibers, UHMWPE,

In fact, and surprisingly, while polyester yarns are much less resistant than aramid fiber yarns, they make it possible to obtain ballistic protection panels that are just as effective because of their much better elongation capacity.

Thus, instead of opposing the penetration of the projectile by the interposition of extremely resistant very high tenacity yarns, the panel according to the invention absorbs and dissipates the kinetic energy of the projectiles by a great capacity for elongation of the yarns as well as by a technical weaving which makes it possible to have more threads per half-cm ² (0.5 cm ² ) which compose it and by the progressive deformation of the successive layers of fabric until obtaining the stop of the projectile and / or fragments of any kind. The choice of the unit of density per half-cm ² is advantageous insofar as an impact of projectiles often takes place on a very small surface.

The multilayer panel according to the invention is thus particularly effective as a splinter guard and as a ballistic coating (ballistic liner) against projectiles of medium hardness (+/- 30 HRc) at high energy, for example of the FSP type (Fragment Simulating Projectiles ) which are difficult to stop by the traditional steel armor. Furthermore, it is not necessary to increase the thickness of the shielding steel, in particular at T° of -40° C. when it is combined with a multilayer panel according to the invention.

In a particularly advantageous manner, it also makes it possible to effectively retain projectile shards and wall fragments propelled in other directions by the projectile and liable to cause very significant damage. This anti-splinter function of the panel according to the invention will be described in more detail in the description below.

According to an essential characteristic of the invention, the polyester yarns of the fabric layers are twisted, preferably twisted Z. Unexpectedly, this characteristic makes it possible to obtain an improvement in the efficiency of the multilayer panel according to the invention by improving its resistance. to projectile penetration.

Indeed, with conventional untwisted yarns, the fibers are all oriented in the same direction corresponding to the longitudinal direction of the yarn. When a projectile strikes such a wire, its pointed end separates its parallel filaments which make up the wire and passes through said filaments. On the contrary, with twisted yarns, for example in the same direction as the direction of rotation of the pointed projectile, the filaments have a much greater cohesion. As a result, these filaments are much more difficult to separate when a projectile strikes the twisted wire and oppose more effectively the penetration of the projectile.

This characteristic has yet another particularly advantageous technical effect, since it makes it possible, by giving a torsion (twist) to the polyester threads, to obtain threads of a finer diameter and more compact. This makes it possible to insert more threads while keeping enough free spaces between the meshes of the woven threads. This improves the penetration of the molten thermoplastic material of the adhesive layers between the yarns of the fabric layers and thus guarantees better bonding of the multilayer panel with less delamination phenomenon.

Through the use of twisted yarns, it is possible to achieve a tighter weave to increase the yarn density of the fabric and thus improve the overall strength of the multilayer panel, while leaving between the yarns free interstices of sufficient size to guarantee satisfactory bonding.

The multilayer panel according to the invention is advantageously modular and adapted, by the choice of the number of fabric layers of the panel, to the nature of the threat which it must face and to the intended application. This choice can be done at initial manufacture and can also be reassessed later by adding additional layers later and/or by adding several already pressed panels, pressing the assembly together, in order to obtain the strength calculated for a specific protection.

Another remarkable advantage of the multilayer panel in accordance with the invention lies in the fact that it is perfectly resistant to fires and burns from incendiary projectiles of the API type and that it does not allow BZ gas (API and API BZ) to pass in particular. BZ gas or 3-quinuclidinyl benzilate being an anticholinergic incapacitating agent blocking the action of acetylcholine in the nervous system.

Another remarkable advantage of the multilayer panel in accordance with the invention lies in the fact that it retains its properties and mechanical characteristics at low temperatures ranging at least down to -54°C. It thus retains a relative flexibility while being insensitive to freezing.

In addition, each face of a multilayer panel according to the invention can be used either as an attack face, unlike a known aramid-based material.

The multilayer panel according to the invention also resists incendiary projectiles, because it does not burn.

Another non-negligible advantage lies in the possibility of cutting the multilayer panel in accordance with the invention using a laser beam. The thermal energy provided by the laser beam makes it possible to achieve a very localized melting along the line of cutting of the constituent thermoplastic material of said multilayer panel. Such a cutting operation makes it possible to make said multilayer panel watertight, in particular by cauterization at the level of the cut edges.

Another remarkable advantage of the multilayer panel in accordance with the invention lies in the fact that it retains all of its mechanical properties and its performance, up to approximately 1 cm from its edge, whereas articles based on aramid fibers and UHMWPE generally have a dead zone (low efficiency) of about 5 cm measured from their edge.

The multilayer panel according to the invention also retains all of its mechanical properties and its performance during multiple projectile impacts which are spaced only 1 cm apart.

Furthermore, the multilayer panel according to the invention has excellent resistance to attacks by sharp objects such as daggers, bayonets or the like.

Brief description of figures

• la figure 1 est une vue schématique en coupe transversale d'un exemple de panneau multicouche selon l'invention ;
• les figures 2 et 3 sont des représentations schématiques d'un tissage respectivement plat pour la figure 2 et natté pour la figure 3, réalisé à l'aide de fils classiques rectilignes (non torsadés) ;
• les figures 4 et 5 sont des représentations schématiques d'un tissage respectivement plat pour la figure 4 et natté pour la figure 5, cette fois réalisé à l'aide de fils torsadés ;
• les figures 6a, 6b et 6c illustrent schématiquement les étapes successives de la pénétration d'un projectile dans un panneau multicouche selon l'invention représenté en coupe ;
• la figure 7a est une vue de face du panneau multicouche de la figure 6c dans lequel le projectile a été arrêté ;
• figure 7b est une vue de profil, en coupe d'un panneau multicouche selon l'invention, illustrant la pénétration et la déformation progressives d'un projectile ;
• la figure 8 est une vue en perspective d'un exemple de panneau composite selon l'invention formé d'une plaque de blindage en acier et d'un revêtement de protection balistique constitué d'un panneau multicouche selon l'invention ;
• les figures 9a et 9b sont des vues schématique en coupe qui illustrent comparativement le comportement de projectiles traversant une plaque d'acier seule pour la figure 9a et une plaque d'acier revêtue d'un panneau multicouche selon l'invention pour la figure 9b ;
• les figures 10a et 10b sont des photographies des deux faces d'un panneau composite, formé d'une plaque en acier revêtue d'un panneau multicouche selon l'invention, ayant subi des essais de tir de plusieurs projectiles ;
• la figure 11a est une vue de face d'un autre exemple de panneau composite selon l'invention formé d'un assemblage de plaquettes hexagonales en céramique, rapportées sur un panneau multicouche selon l'invention ;
• la figure 11b est une vue de profil, en coupe, d'un autre exemple de réalisation d'un panneau composite selon l'invention;
• les figures 12a, 12b et 12c sont des vues schématiques en coupe qui illustrent comparativement le comportement d'un projectile traversant une plaquette de céramique, seule pour les figures 12a et 12b, et revêtue d'un panneau multicouche selon l'invention pour la figure12c ;
• la figure 13 est une vue schématique en coupe qui illustre le procédé de fabrication d'un panneau multicouche selon l'invention par pressage à chaud sous pression.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows, which is given by way of indication and in no way limiting, with reference to the appended drawings, in which:

• the figure 1 is a schematic cross-sectional view of an example of a multilayer panel according to the invention;
• them figures 2 and 3 are schematic representations of a respectively flat weave for the picture 2 and braided for the picture 3 , made using conventional straight yarns (not twisted);
• them figures 4 and 5 are schematic representations of a respectively flat weave for the figure 4 and braided for the figure 5 , this time made using twisted yarn;
• them figures 6a, 6b and 6c schematically illustrate the successive steps of the penetration of a projectile into a multilayer panel according to the invention shown in section;
• the figure 7a is a front view of the multilayer panel of the figure 6c in which the projectile was stopped;
• figure 7b is a side view, in section, of a multilayer panel according to the invention, illustrating the progressive penetration and deformation of a projectile;
• the figure 8 is a perspective view of an example of a composite panel according to the invention formed of a steel armor plate and a ballistic protective coating consisting of a multilayer panel according to the invention;
• them figures 9a and 9b are schematic sectional views which comparatively illustrate the behavior of projectiles passing through a single steel plate for the figure 9a and a steel plate coated with a multilayer panel according to the invention for the figure 9b ;
• them figures 10a and 10b are photographs of the two faces of a composite panel, formed of a steel plate coated with a multilayer panel according to the invention, having undergone firing tests with several projectiles;
• the picture 11a is a front view of another example of a composite panel according to the invention formed of an assembly of hexagonal ceramic plates, attached to a multilayer panel according to the invention;
• the figure 11b is a side view, in section, of another embodiment of a composite panel according to the invention;
• them figures 12a, 12b and 12c are schematic cross-sectional views illustrating compared the behavior of a projectile passing through a ceramic plate, only for the figures 12a and 12b , and coated with a multilayer panel according to the invention for the figure12c ;
• the figure 13 is a schematic sectional view which illustrates the method of manufacturing a multilayer panel according to the invention by hot pressing under pressure.

Detailed disclosure of the invention

The multilayer ballistic protection panel according to the present invention will now be described in detail with reference to the figures 1 to 13 . The equivalent elements shown in the various figures will bear the same numerical or alphanumeric references.

Several embodiments of a multilayer panel 1 for ballistic protection have been shown in the various figures.

The one represented in section on the figure 1 comprises four layers of fabric 2 between which are interposed three layers of adhesive 3.

Of course, this is only an illustrative example, the number of layers being adapted to the protection sought and possibly ranging for example between 5 and 120 layers of fabric, or even more if necessary and depending on the capacity of opening of the press allowing the introduction of large thicknesses according to the protection needs of the applications.

The fabric layers 2 are made from polyester yarns 4 (polyethylene terephthalate, also called oxyethylene oxyterephthaloyl PET) which are woven to form the fabric 2.

Depending on how the polyester yarns 4 are interlaced, different weaving patterns are obtained. The multilayer panel of the invention is not limited to a particular weaving pattern for the production of the fabric 2, several patterns being able to be perfectly suitable.

One can thus advantageously use a flat weave as shown in the picture 2 for which each time a weft thread 5 crosses a warp thread 6, or a basket weave, also called panama weave, as shown in the picture 3 in which the threads intersect each time in pairs, two weft threads 5 crossing two warp threads 6.

But whatever the pattern chosen, there are, because of this weaving, interstices 7 which are free spaces crossing, located between the threads 4 and more precisely between the stitches formed by the interlacing of the threads 4.

The adhesive layers 3 are composed of a thermoplastic material 8, consisting of one or more chemical compounds based on polyethylene LLDPE - LDPE & HDPE (used in this case as a hotmelt).

As can be seen on the figure 1 , the thermoplastic material 8 passes through the layers of fabric 2 passing through the interstices 7 existing between the meshes of the fabric and connects the layers of adhesive 3 with each other. Preferably, the thermoplastic material 8 completely fills all the interstices 7 of the layers of fabric 2 and completely covers and surrounds the layers of fabric 2, even forming a film of thermoplastic material 8 on the surface of the panel 1 on its upper face 9 and its underside 10 in particular. The thermoplastic material 8 thus advantageously ensures the overall cohesion of the multilayer panel 1.

Advantageously, the adhesive layers should preferably be colored and not transparent. This allows the exit of the press after a visual control on the panel, to verify that the bonding is optimal by simply observing the homogeneity of the color on all its surface of the panel.

The polyester threads 4 are conventionally composed of a multitude of straight polyester filaments, oriented substantially along the longitudinal direction of the thread as shown diagrammatically in the figures 2 and 3 .

To produce the multilayer panel according to the invention, twisted polyester yarns 4 are advantageously used as represented diagrammatically on the figures 4 and 5 . The polyester yarns are thus twisted on themselves several times according to a torque oblique to the longitudinal direction of the yarn.

The polyester yarns 4 used have thus undergone a number of twists that vary according to the embodiments, but generally between 40 to 80 twists per meter of yarn and preferably corresponding to about 60 twists per meter of yarn.

We thus notice, as we can see on the figures 4 and 5 , that in the case of twisted yarns, the interstices 7 are larger than with the untwisted yarns of the figures 2 and 3 . A greater quantity of thermoplastic material 8 can thus pass through the fabric 2 to unite the different layers of adhesive 3 and improve the overall cohesion of the multilayer panel 1.

In order to obtain a multilayer panel 1 of high resistance, high tenacity yarns 4 having a resistance between 75 N and 110 N and preferably between 101.5 N - 103.9 N.

These yarns preferably have an elongation of between 8 and 25%, and preferably between 12-14%, giving them a larger deformation range than aramid and UHMWPE fibers (whose elongation is between 2.4 and 3 .5%), to absorb projectile energy.

The count of the yarns 4 chosen is variable and for example between 800 and 4000 denier, preferably between 1000 and 3000 denier, and even more preferably close to 1000 den (1100 dtex).

With such twisted threads, it is possible to achieve a very tight weave in order to increase the density of threads to half a square centimeter, which is very important for stopping sharp projectiles of small diameters (5-8mm). At the same time, the resistance of the fabric 2 is increased, while guaranteeing satisfactory bonding due to the presence of gaps 7 of sufficient size.

With twisted polyester yarns with a count equal to 1000 denier, it is thus possible, for example, to obtain a density (in number of warp yarns by number of weft yarns per 1/2 cm ² of fabric) of between 5x5 and 8x8, and preferably 7x7.

By way of example, multilayer panels 1 comprising between 40 and 50 layers of fabric 2 have been made with these fabrics 2. Panel 1 comprising 45 layers of fabric 2 has been preferred.

With twisted polyester yarns of denier equal to 3000 denier, it is possible for example to obtain, for fabric 2, a density of between 3.35×3.35 and 5×5, preferably 4.53×4.53 for twisted polyester yarns of title equal to 3000 den.

By way of example, multilayer panels 1 comprising between 15 and 22 layers of fabric 2 have been made with these fabrics 2. Panel 1 comprising 18 layers of fabric 2 has been preferred.

In order to illustrate the principle of the ballistic protection function of the multilayer panel 1 according to the invention, the course of a projectile striking the multilayer panel 1 at the level of its upper face 9 has been represented chronologically on the figures 6 to 7a and 7b .

As can be seen from the chronological sequence of figures 6a to 6c , when a projectile 12 reaches the upper face 9 of the multilayer panel 1, it begins by sinking into the thickness of the panel by digging a basin 13 there. Thanks to its high kinetic energy enabling it to break the threads 4, it passes through the first 2 layers of fabric. It is however braked and deformed gradually by the layers of fabric 2 which, before breaking, become deformed due to the high elongation capacity of the polyester threads 4 and which in this way absorb a large part of the energy of the projectile 12.

Thus, the figure 7b illustrates the penetration of the projectile 12, which deforms the successive layers of fabric 2 and deforms progressively to present a shape substantially of a mushroom that becomes more and more marked depending on the degree of penetration into the multilayer panel 1. The resistance of the layers of fabric 2 not perforated by the projectile 12 causes the deformation of said projectile 12. The contact surface of the projectile 12 thus increases and consequently its braking also increases.

If the number of layers of fabric 2 of the multilayer panel 1 is sufficient, the projectile 12 ends up coming to rest without passing through the underside 10 of the multilayer panel 1, as shown in section on the figure 6c or seen from above on the figure 7a .

The multilayer panel 1 according to the invention, used alone, thus makes it possible to effectively stop bullets from pistols, revolvers and submachine guns and projectiles with moderate kinetic energy such as buckshot and bullets. It is therefore perfectly suited for the production of inserts (Breastplates) for vests, jackets or other bulletproof clothing or very thin and flexible inserts to be inserted on the rear part, to reduce trauma and increase the level of resistance relative to existing bulletproof vests made of aramid fibers or UHMWPE.

Furthermore, as seen in the figure 6c , the panel 1 has, after the impact of the projectile 12, a limited deformation on its underside 10 preventing the occurrence of serious internal trauma when it is used as a trauma reducer in bulletproof vests.

Depending on the type of projectiles to be resisted, it is possible to combine the multilayer panel 1 with very high hardness steel or ceramic to retain the projectiles 12 with hardened steel and Tungsten cores, which are much harder materials.

To deal with perforating and incendiary projectiles, a composite panel 14 can be produced comprising at least one armor wall 15 and a multilayer panel 1 serving as a ballistic protective coating 16 (also called a “ballistic liner”) as shown in figure figure 8 .

The multilayer panel 1 serving as a ballistic protective coating 16 is preferably assembled against the armor wall 15 by gluing or by mechanical fixing. It can also be fixed at a certain distance from the shield wall 15.

Advantageously, the shielding wall can be a steel plate 17 and preferably a steel plate having a hardness of 600HB according to standard EN ISO 6506-1.

The composite panel 14 is then able to effectively retain projectiles from portable infantry weapons in general as well as metal fragments from hand grenades and landmines.

In this configuration (when the multilayer panel 1 is used as a ballistic liner), it additionally performs an interesting function as a splinter guard represented on the figures 9a and 9b .

Indeed, even if they are retained by the shielding wall 15, for example made of steel, the projectiles 12 can break and project projectile fragments 18 or tear off fragments of wall 19 which are projected in different directions from the initial trajectory of the projectile 12 and can turn out to be extremely deadly. The occupants of an armored vehicle whose steel wall has retained an armor-piercing projectile 12 can thus be very seriously injured by fragments of this wall when they were not even in the path of the projectile.

As can be seen on the figure 9b , when the wall 15 is covered with a multilayer panel 1, the projectile fragments 18 and the wall fragments 19 are retained by the multilayer panel 1 which deforms to contain them in a bowl 13, regardless of the direction in which they are propelled.

In order to demonstrate the effectiveness of the invention, ballistic tests were carried out on several an example of implementation of the invention consisting of a multilayer panel 1 comprising 45 layers of fabric 2, glued in contact with a plate of 7.5 mm thick ballistic protection steel 17 with a nominal hardness of 600 HB, on which armor-piercing projectiles and 20 mm caliber FSP projectiles were fired in accordance with STANAG 4569 level 2 at -40°C .

The photographs after impacts of the two faces of the composite panel 14 tested are presented on the figures 10a and 10b .

As can be seen on the figure 10a , three armor-piercing projectiles (2-1, 2-2 and 2-3) and three FSP projectiles (1, 2 and 3) reached the composite panel 14 and impacted its steel plate 17.

As seen on the figure 10b , none of these projectiles passed through the composite panel 14 and tore the outer face of the multilayer panel 1, thus demonstrating the effectiveness of the composite panel 14 in material ballistic protection.

Such composite steel/multilayer panel panels can be used, for example, to produce shielding walls for civilian vehicles, police forces, cash transport and the military.

Depending on the applications, the shielding wall 15 can also be formed from a plate of ceramic material or, as shown in the picture 11a , of a set of ceramic plates 22, for example hexagonal, retained by a binder 23.

The figure 11b illustrates, by way of example, another example of application of the multilayer panel 1. The latter is for example sandwiched between a ceramic armor plate 15 and a steel or aluminum plate 30 using adhesive layers 31. A such shielding sub-assembly can then be bonded via an additional adhesive layer 32 and/or mechanically fixed by bolting with a bolt-nut assembly 32a to an outer wall 33 made of steel, aluminum or other material.

The anti-splinter function of the multilayer panel 1 in association with a shielding wall 15 made of ceramic plates has also been represented on the figures 12a to 12c .

On the figures 12a and 12b , it can be seen that when the ceramic shielding wall 15 is alone, the projectile 12 passes through it, fracturing and disintegrating the ceramic plate 22 and the binder 23. The projectile 12 can emerge by continuing its course, while projecting fragments of wall 19 in other directions.

When the ceramic shielding wall 15 is combined with a multilayer panel 1, as shown in the figure 12c , the projectile 12 like the wall fragments 19 are retained by the multilayer panel 1 serving as a ballistic liner.

With a ceramic armor plate 15, the composite panel 14 is able to resist effectively against projectiles from large caliber military weapons or against multiple projectiles.

Such ceramic composite panels/multilayer panel can be used for example to produce shields.

The multilayer panel 1 according to the invention is preferably a compact laminate panel, also called compact laminate, produced by hot pressing under high pressure. To achieve this, an HPL (High Pressure Laminate) type thermo-lamination press is used, capable of producing heating and cooling cycles (Hot/Cooled) under high pressure.

An example of a method of manufacturing a multilayer panel 1 according to the invention has been illustrated schematically in the figure 13 .

After having made or purchased the necessary layers of fabric 2 and layers of adhesive 3, a superposition 24 is made by stacking alternately the layers of fabric 2 and the layers of adhesive 3.

This superposition 24 is then placed between the two plates 25 of a press 26 of the HPL type thermo-lamination. Alternatively, the overlay 24 can be made directly inside the press 26.

The press is closed and a heating cycle is initiated in order to obtain the melting of the thermoplastic material 8 of the layers of adhesive 3. Inside the press, the temperature is thus gradually increased to a value between 135 °C and 165°C.

Once the thermoplastic material 8 has reached its melting point (melting point), the pressure inside the press is increased, up to a value preferably between 90 and 200 bars and for example equal to 110 bars, by so as to compact the superposition 24 by bringing the two plates 25 of the press 26 towards each other as symbolized by the arrows 27 of the figure 13 . The choice of temperature and pressure values within the ranges mentioned above depends on the thickness of the multilayer panel 1 to be produced.

This causes the passage of the molten thermoplastic material 8 through the interstices 7 of the layers of fabric 2. The gradual increase in pressure causes the thermoplastic material to completely fill the interstices 7 and connect the different layers of adhesive 3. It even covers the upper and outer layers of fabric 2, thus constituting a film of thermoplastic material on the upper 9 and lower 10 faces of the panel 1.

This placing under very high pressure of the superposition 24 also makes it possible to obtain a compression of its various layers of fabric 2 and of adhesive 3, thus leading to the obtaining of a compact multilayer panel 1 (i.e. say whose final height is less than the sum of the initial height of the layers composing it).

A cooling cycle is then carried out inside the press 26 while maintaining the maximum pressure on the panel. The temperature is thus reduced to a value preferably between 50 and 70°C and for example of the order of 60 to 65°C. On cooling, the thermoplastic material 8 solidifies and then ensures the cohesion of the superposition 24 in the form of a compact multilayer panel 1,

One can then open the press 26 and take out the multilayer panel 1 obtained.

In this way and depending on the shape of the plates 25 of the press 26, flat panels or shaped pieces can be obtained.

Other variants of the multilayer panel 1 according to the invention can obviously be imagined without departing from the scope of the claims below.

The multilayer panel 1 may for example further comprise at least one decorative outer layer, on one or both of its outer faces. This decorative layer can advantageously be added directly during the pressing of the multilayer panel. It may be in particular a plastic or paper decoration glued with a film of melanin called an “overlay”.

According to another exemplary embodiment, the fabric layers 2 of the multilayer ballistic protection panel 1 may comprise, in addition to the fabric layers made of 1000 den polyester yarn, at least one layer woven with aramid or polyethylene yarns of very high molar mass. high (UHMWPE) or preferably, for reasons of economy, with a layer woven with 3000 den polyester yarns on the outer face(s).

Claims (20)

1. A multilayer ballistic protection panel (1) comprising a stack of layers of fabric (2) of woven yarns (4), the weave leaving through-interstices (7) free between the yarns (4) of each layer of fabric (2), and layers of adhesive (3) which are interposed between the layers of fabric (2) in an alternating manner and which provide overall cohesion to the multilayer panel (1),

   the layers of fabric (2) of woven yarns (4) comprising layers of woven fabric (2) made of twisted polyester yarns (4),

   the layers of adhesive (3) being layers of a thermoplastic material (8) based on polyethylene,

   and the thermoplastic material (8) passing through the interstices (7) of the layers of fabric (2) and connecting the layers of adhesive (3) with one another, thereby ensuring cohesion of the multilayer panel assembly (1).
2. The multilayer ballistic protection panel (1) as claimed in claim 1, characterized in that it is a compact stratified panel produced by high pressure hot pressing
3. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the fabric of layers of fabric (2) woven with twisted polyester yarns (4) is woven in accordance with a plain or basket weaving pattern.
4. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the polyester yarns (2) are Z or S twisted, more preferably Z twisted, with 40 to 80 twists per metre of yarn and preferably approximately 60 twists per metre of yarn.
5. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the polyester yarns (2) have a strength in the range 75 N to 110 N and preferably in the range 101.5 N to 103.9 N.
6. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the polyester yarns (2) have an elongation in the range 8% to 25%, preferably in the range 12% to 14%.
7. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the polyester yarns (2) have a yarn count in the range 800 to 4000 den, preferably in the range 1000 to 3000 den and preferably close to 1000 den.
8. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that it comprises between 5 and 120 layers of fabric (2) woven with twisted polyester yarns (4).
9. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that comprises between 40 and 50 layers of fabric (2), and preferably 45 layers of fabric (2), woven with twisted polyester yarns with a yarn count equal to 1000 den.
10. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that comprises between 15 and 22 layers of fabric (2), and preferably 18 layers of fabric (2), woven with twisted, preferably Z twisted, polyester yarns (4), with a yarn count equal to 3000 den.
11. The multilayer ballistic protection panel (1) as claimed in any one of the preceding claims, characterized in that the fabric of the layers of fabric (2) is woven with a density, as the number of warp yarns per number of weft yarns per 0.5 cm² of fabric, in the range 5x5 to 8x8 and preferably close to 7x7 for twisted, preferably Z twisted, polyester yarns, with a yarn count equal to 1000 den.
12. The multilayer ballistic protection panel (1) as claimed in any one of claims 1 to 10, characterized in that the fabric of the layers of fabric (2) is woven with a density, as the number of warp yarns per number of weft yarns per 0.5 cm² of fabric, in the range 3.35x3.35 to 5x5 and preferably close to 4.53x4.53 for twisted, preferably Z twisted, polyester yarns (4), with a yarn count equal to 3000 den.
13. Use of a multilayer ballistic protection panel (1) as claimed in any one of claims 1 to 12, for the production of an interior or exterior liner of a vehicle, of a ballistic protection garment or accessory or of a door, wall or partition cladding.
14. An armoured composite panel (14) comprising a shielding wall (15) and a ballistic protection liner (16), characterized in that the ballistic protection liner (16) is a multilayer ballistic protection panel (1) as claimed in any one of claims 1 to 12.
15. The armoured composite panel (14) as claimed in claim 14, characterized in that the shielding wall (15) is a steel plate (17), an aluminium plate, an aluminium foam, a titanium plate, a glass fibre plate, a multilayer aramid fibre plate, a multilayer plate produced from UHMWPE, a polycarbonate plate, an assembly of perforated metal plates or a monolithic ceramic plate, or an assembly of ceramic platelets (22).
16. The armoured composite panel (14) as claimed in claim 14 or claim 15, characterized in that the multilayer ballistic protection panel (1) is fastened to the shielding wall (15) by bonding or mechanical fastening.
17. The armoured composite panel (14) as claimed in any one of claims 14 to 16, characterized in that it is a wall element of a vehicle, a construction panel, a door, a wall or a partition, a portion of a furnishing element, a wall of seating, or an element of ballistic protection apparel, helmet or shield.
18. A production process of a multilayer ballistic protection panel (1) as claimed in any one of claims 1 to 14, comprising the following steps:

    - . producing or providing layers of woven fabric (2) made of twisted polyester yarns (4) and layers of adhesive (3) made of thermoplastic material (8) based on polyethylene,

    stacking alternating layers of fabric (2) and layers of adhesive (3),

    placing the stack (24) or producing it directly on a plate (25) of a High Pressure Lamination (HPL) type hot lamination press (26),

    closing the press and increasing the temperature and the pressure on the stack to a value for the pressure which is sufficient to enable good diffusion and distribution of heat inside the press in a manner such as to cause the thermoplastic material of the layers of adhesive to melt and to compact the stack in order to cause the molten thermoplastic material to pass through the interstices of the layers of fabric until it comes into contact with the adj acent layers of adhesive,

    then initiating the cooling cycle of the press, without opening the press and maintaining the maximum pressure exerted on the stack, in order to cause the thermoplastic material to solidify, thereby ensuring the cohesion of the stack in the form of a compact multilayer panel,

    opening the press (26) and removing the multilayer panel (1).
19. The production process as claimed in the preceding claim, characterized in that the temperature is increased to a value in the range 135°C to 165°C at the core of the multilayer panel (1) depending on the thickness of the multilayer panel (1), and the pressure is increased to a value in the range 90 to 200 bar (kg/cm²) and preferably to a value of 110 bar (kg/cm²).
20. The production process as claimed in claim 18 or claim 19, characterized in that the temperature is reduced to a value in the range 50°C to 70°C and preferably in the range 60°C to 65°C, before opening the press (26) in order to remove the multilayer panels (1).

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