Energy dissipation plate comprising fibrous porous damping material for protective clothing

Abstract

An impact energy dissipation plate for ballistic protectors, the dissipation plate consisting of a damping material consisting of a fibrous reinforcement bonded by an organic matrix comprising a thermosetting resin, the reinforcement comprising inorganic fibers combined in the form of yarns, the damping material has the following features: the volume fraction of the fibrous reinforcement of the damping material is 20% to 70%, the remainder consisting of the matrix and pores being supplemented to 100%; -the fibrous reinforcement comprises at least 50% by volume of silica fibrous yarns, the SiO2 mass content of which is greater than 90%, and-the porosity of the damping material is from 2% by volume to 10% by volume.

Description

[0001] The present invention relates to ballistic protection devices, in particular personal protection devices (such as bulletproof vests), protection devices for vehicles (land, sea or air) or fixed facilities (such as buildings, walls, sentry boxes), or detection or communication equipment (such as antenna covers).

[0002] The present invention more particularly relates to an energy dissipation plate for protective gear, which contains a damping material, including the material itself. In particular, such a plate can stop bullets or projectiles fired from a weapon, especially a firearm.

[0003] The invention also relates to a protective gear plate, which comprises the energy dissipation plate and an impact plate made of hard material, which is placed in front of the energy dissipation plate relative to the direction of the threat or projectile. This type of design is particularly suitable for enhancing protection when the projectile has a high penetration.

[0004] In ballistic protection materials, e.g. HB26, known from US2013220106A1, is a composite material comprising several layers of unidirectional ultra-high molecular weight polyethylene (UHMWPE) fibers, arranged vertically from one layer to the next in a polyurethane matrix. This material will be used to protect against ammunition used by assault rifles such as AK47, or to protect against the impact of improvised bombs by dispersing the impact energy.

[0005] In order to reduce the mass of the protective device without affecting the ballistic performance, many materials have been proposed to form personal protective equipment, for which the ratio of the mass of the protective equipment to the protected surface must be kept low, usually less than 50 kg / m2, or non-personal protective equipment for carriers or fixed facilities, for which the ratio of the mass to the protected surface is usually higher than 20 kg / m2. Ceramic materials particularly used in such applications are products based on metal carbides. For example, WO 2013 / 186453A1 describes a silicon carbide (SiC) product with a specific grain shape and chemical composition to form impact protective equipment or protective equipment elements. EP1710218A1 discloses a sintered material based on silicon nitride and tungsten carbide, with the help of additives such as rare earths, tungsten, which are preferably added in oxidized form.

[0006] WO2008 / 130451 (EP2095055A1) also proposes a method that aims to reduce the propagation of stress waves associated with projectile impact by using a shell formed by a permeable medium, which is usually a layer of organic fibers (such as aromatic polyamide) fixed to a ceramic part and then impregnated with a superelastic polymer, so as to absorb the energy associated with projectile impact and reduce the propagation of cracks and multiple fractures of the ceramic material.

[0007] However, there is a continuous need to improve ballistic protection devices, as measured in particular by their impact performance relative to their mass, in particular so that they can resist dynamic deformations due to projectile impact without increasing their mass, or even while reducing their mass, in particular to improve comfort in the case of personal protection or to reduce energy consumption in the case of vehicle protection.

[0008] The object of the present invention is therefore to provide a ballistic armour plate which, for the same surface density, has improved properties, in particular improved resistance to dynamic deformations. This improvement is especially due to the use of a plate made of a damping material according to the invention as described below.

[0009] According to a first general aspect, the present invention relates to an impact energy dissipation plate for ballistic armor, the dissipation plate consisting of a damping material consisting of a fiber reinforcement bound by an organic matrix, the reinforcement comprising inorganic fibers combined in the form of yarns, preferably filaments, the matrix comprising a thermosetting resin coating the yarns, the damping material having the following characteristics:

[0010] - the volume fraction of the fiber reinforcement of the damping material is between 20% and 70%, the remainder making up to 100% being composed of the matrix and the pores of the material;

[0011] - the fiber reinforcement comprises at least 50% by volume of silica fiber yarns having a SiO2 weight content greater than 90%,

[0012] The porosity of the damping material is between 2% and 10% by volume.

[0013] The inventors have found that such a damping material in the form of a controlled porosity composite material comprising an organic matrix encapsulating a reinforcement comprising yarns having a high silica content provides improved resistance to dynamic deformation compared to prior art materials at the same surface density.

[0014] In particular, armor plates provided with such damping material show a shallower deformation depth and a larger lateral deformation surface, which translates into a greater ability to absorb energy due to an impact (for example, of a projectile fired by a firearm) at an equivalent mass.

[0015] Various preferred embodiments according to the present invention are described below, and of course, they can be appropriately combined with each other:

[0016] - The bulk density of the damping material is greater than 1.0g / cm 3 , preferably greater than 1.5 g / cm 3 and / or less than 2.0g / cm 3, preferably less than 1.8 g / cm 3 ;

[0017] The damping material has a fiber reinforcement volume fraction of 30% to 50%, the remainder consisting of porosity and matrix.

[0018] - the fiber reinforcement comprises at least 70% by volume of silica fiber yarns, preferably at least 80%, more preferably more than 90% of silica fiber yarns, preferably consists essentially of silica fiber yarns, hereinafter referred to as silica yarns for simplicity;

[0019] - at least 50% of the volume complement of said silica yarns of the fiber reinforcement is represented by washed glass fibers.

[0020] - the SiO2 mass content of the silica yarn is greater than 95%, preferably greater than 97%, more preferably at least 99%;

[0021] - the average equivalent diameter of the yarn is between 3 and 3000 microns, preferably greater than 8 microns and / or less than 1000 microns, preferably less than 500 microns;

[0022] - the yarn is preferably a single yarn;

[0023] - the linear density of the yarn is greater than or equal to 500 tex, preferably less than 5000 tex;

[0024] - the average equivalent diameter of the silica fibers constituting the yarn is greater than or equal to 3 microns, preferably greater than or equal to 5 microns, even more preferably greater than or equal to 7 microns

[0025] - the average equivalent diameter of the fibers is less than or equal to 20 microns;

[0026] - the reinforcement consists essentially of or even consists of said silica yarn;

[0027] - the yarn twist is on average less than or equal to Z20, preferably less than or equal to Z10, more preferably less than or equal to Z3;

[0028] - the fiber reinforcement is in the form of at least one sheet or layer of a textile, preferably a woven fabric, consisting of a network of parallel warp threads, preferably weft threads running transversely, preferably vertically through the network. In one possible embodiment, the reinforcement consists of several superimposed fabric layers, each impregnated with resin to form the damping material. Preferably, the superimposed fabric layers have the same pattern or weave. This has the advantage of avoiding the phenomenon of interpenetration or interweaving of the yarns of one layer with the yarns of the layer directly in contact below or above;

[0029] - The weight of the textile layer or fabric piece is greater than or equal to 350 g / m 2 , preferably less than 2000g / m 2 , more preferably less than 1000g / m 2 , most preferably less than 700g / m 2 A lower grammage means a greater number of fabric layers, making the manufacturing process longer and therefore more expensive. Too much grammage results in poorer equivalent weight / unit area performance.

[0030] - the porosity of the damping material is less than or equal to 5% by volume;

[0031] - the matrix has pores having an average width of from 10% to 500% of the average equivalent diameter of the fibers, preferably from 10% to 100% of said diameter, more preferably from 10% to 50% of said diameter. Preferably, by number, more than 90%, preferably more than 95%, more preferably more than 99% of the pores have a width greater than 1 micron, preferably greater than 2 microns, more preferably greater than 5 microns and / or less than 50 microns, preferably less than 30 microns, more preferably less than 15 microns;

[0032] - the matrix optionally comprises additives, such as mineral fillers;

[0033] - The density of the resin is 0.8 to 1.35 g / cm 3 ;

[0034] - The resin essentially contains the chemical elements carbon (C), hydrogen (H) and oxygen (O);

[0035] - the matrix comprises epoxy resin;

[0036] - the damping material has a Vickers hardness of less than 3 GPa;

[0037] - The dissipation plate has a diameter greater than or equal to 150 cm 2 Surface area and / or thickness of 1 to 50 mm, preferably 3 to 20 mm;

[0038] - said dissipation plate is surrounded by a wrapping of protective material,

[0039] -The ballistic armor plate comprises the impact energy dissipation plate.

[0040] In particular, in some embodiments of the present invention, an impact plate can be placed in front of the plate to absorb or dissipate impact energy to resist high-penetration projectiles, such as those meeting NIJ-IIIA, NIJ-III or NIJ-IV standards for personal protection or STANAG 4569 for non-personal protection.

[0041] According to a second general aspect, the invention thus relates to a protector plate as previously described, further comprising an anti-impact plate made of a material having a stiffness greater than that of the damping material. The anti-impact plate is typically thicker than 2 mm and is placed in front of the dissipation plate with respect to the impact direction.

[0042] Other preferred embodiments of the present invention are described below, which can of course be combined with each other where appropriate, describing the case where the protective gear plate includes an anti-impact plate in addition to the above-mentioned damping plate:

[0043] - the thickness of the anti-impact plate is greater than 4 mm, preferably 6 mm, more preferably greater than 10 mm. According to a possible embodiment, the thickness of the plate is less than 100 mm, preferably less than 50 mm, or even less than 20 mm;

[0044] - the ratio of the thickness of the energy dissipation plate to the thickness of the impact resistant plate is preferably 0.5 to 5, preferably greater than 1 and / or less than 3;

[0045] - The surface area of ​​the impact-resistant plate is greater than 150cm 2 ;

[0046] - the surface area of ​​the energy dissipation plate is at least 80% of the surface area of ​​the impact resistant plate;

[0047] The material of the impact-resistant plate has a Vickers hardness greater than 3 GPa, preferably greater than 5 GPa, more preferably greater than 10 GPa;

[0048] -The bulk density of the impact-resistant board is less than 10g / cm 3 , preferably less than 7g / cm 3 , more preferably less than 5g / cm 3 , more preferably less than 3.2 g / cm 3 , more preferably less than 3.0 g / cm 3 and / or greater than 1.0 g / cm 3 ;

[0049] - the material of the impact-resistant plate is a sintered material containing grains, preferably consisting of metal carbides or metal borides. More preferably, the grains are silicon carbide or boron carbide grains or a mixture of these two carbides;

[0050] - according to one possible embodiment, the grains are only grains of silicon carbide, possibly with a metallic phase, preferably containing elemental silicon;

[0051] - According to a possible embodiment, the grains of the sintered material are bound by a matrix comprising or consisting of a silicon nitride phase (Si3N4) and / or a silicon oxynitride phase (Si2ON2) and / or SiAlON;

[0052] - according to a possible embodiment, said grains of said sintered material are bound by a matrix which preferably represents from 5% to 40% by mass, preferably from 15% to 35% by mass, of the mass of the material of said anti-impact plate;

[0053] - the impact resistant plate is bonded to the energy dissipating plate by means of an adhesive selected from adhesives based on, for example, polyurethane, epoxy polymers or thermoplastic polymers or elastomers;

[0054] - The pannier plate is surrounded by a wrapping of protective material.

[0055] According to a third general aspect, the protective plate according to the invention comprises the impact energy dissipation plate, at least partially, preferably completely, covered by a wrapping made of a protective material, for example in the form of a textile, the textile, for example a fabric, comprising glass fibers, or carbon fibers, or polyethylene PE, in particular ultra high density polyethylene (UHMPE), or aromatic polyamide, in particular or metals such as aluminum or even steel, especially in non-personal protection situations.

[0056] The present invention also relates to a method for manufacturing the damping material as described above or a dissipation plate containing the material, the method comprising the following steps:

[0057] 1) preparing, preferably by weaving, at least one fiber layer comprising yarns of silica fibers having a mass content of SiO2 greater than 90%, thereby obtaining a reinforcing material comprising at least 50% by volume of said yarns;

[0058] 2) preparing a mixture comprising a thermosetting resin having a viscosity measured using a 20 mm diameter plate / plate rheometer with a 1 mm air gap between 100 and 200 s -1 The shear rate is 80 to 300 Pa.s measured at 50°C;

[0059] 3) impregnating individual fiber layers with the mixture and stacking the individual layers to obtain a preform, wherein the volume fraction of the fiber reinforcement of the damping material is 20% to 70%;

[0060] 4) Curing the preform in an autoclave under controlled pressure and temperature to polymerize and crosslink the resin and form reinforcements bonded by an organic matrix constituting the damping material.

[0061] 5) Optionally, the resulting damping material is formed into a plate, in particular by cutting or deburring.

[0062] Various preferred embodiments according to the present invention are described below, and of course, they can be appropriately combined with each other:

[0063] - The organic matrix resin is a thermosetting resin selected from phenolic resins; epoxy resins; polyimide resins; polyurethanes; or derivatives thereof, or mixtures of these products. - The resin additive is selected from: catalysts, reinforcing agents, mold release agents and hardeners.

[0064] The resin mixture accounts for at least 30 mass %, preferably more than 35 mass %, more preferably 40 mass % and less than 70 mass %, preferably less than 60 mass %, more preferably less than 55 mass % based on the mixture from step 2).

[0065] The resin is preferably an epoxy resin. The epoxy equivalent weight of the resin measured according to ASTM D1652 is greater than 200, preferably greater than 220. This is the mass of the resin in grams required to provide one mole of epoxy groups. A lower weight results in a resin having a higher bonding surface with the silica yarns of the fiber reinforcement, while the dissipative material has a lower porosity.

[0066] The preform is preferably cured at 1 to 5 bars at less than 200°C. Preferably, it comprises a first stage with a step between 80 and 120°C, and preferably a second stage with a step between 130 and 180°C.

[0067] The invention also relates to the use of a dissipation plate or a protective gear plate as described above as ballistic protection for:

[0068] - Anti-ballistic protection for people, said protection being selected from a bulletproof vest, a helmet or

[0069] - ballistic protection of land, sea or air vehicles, or

[0070] - ballistic protection of fixed installations selected from buildings, walls or guardhouses, or

[0071] -Ballistic protection of radomes, detection or communication equipment (especially optoelectronic equipment).

[0072] Without departing from the scope of the invention, such use may be realized in the form of a plate, a tile, a mosaic (for example in the form of hexagons or small round blocks), a breast plate, a shield, a helmet, a door, a seat or a tube.

[0073] The following descriptions and definitions are given in conjunction with the foregoing description of the present invention:

[0074] - A "fiber" is a structure oriented in one direction and made of the same material, whose length is greater than 5 times its equivalent diameter.

[0075] - "Long fibers" are fibers whose length is greater than 1 mm and less than 10 mm.

[0076] - "Continuous fibers" are fibers having a length exceeding 10 mm.

[0077] - Yarn is composed of multiple fibers. "Long yarn" is a yarn composed of long fibers. "Continuous yarn" is a yarn composed of continuous fibers longer than 10 mm.

[0078] - The equivalent diameter of a fiber or yarn is the diameter of a disk having the same surface area as the cross section of the fiber or yarn at mid-length.

[0079] - A "single yarn" is a collection of fibers which in cross section comprises more than 10 and preferably less than 500,000 fibers and whose length is greater than 5 times the diameter. The fibers are assembled in such a way that they are twisted or untwisted on themselves according to the twist direction, S or Z, and whose index ranges from 0 to 30 corresponding to the number of twists per meter. The twist Z0 corresponds to a yarn in which the fibers are not twisted and are arranged in parallel.

[0080] - A "combination yarn" is a combination of single yarns, which preferably comprises more than 2, and more preferably less than 500 single yarns in cross section.

[0081] - The parallel combination of single yarns used to align the single yarns (or "short yarns") after warping is also a secondary combination.

[0082] - Textiles can be:

[0083] - Organized structures of single or combined yarns, in particular knitted, woven, canvas, woven fabrics or

[0084] - Random structures of single yarns or combined yarns, such as canvas, and / or fibers not combined in yarn form, such as paper or felt, are not preferred.

[0085] -The weave of a fabric refers to the way the yarns cross over each other, helping to define a specific pattern.

[0086] The equivalent diameter of a grain is defined as half the sum of the maximum length of the grain and the maximum width of the grain measured in a direction perpendicular to said maximum length.

[0087] - The maximum and average equivalent diameters of particles, fibers or yarns are usually determined by observing the microstructure of the material, usually using SEM (scanning electron microscope) images of a cross section of said material.

[0088] - The term "matrix" refers to a crystalline or amorphous phase providing a substantially continuous structure between the grains or fibers or yarns in the case of a fibrous material, which is obtained from the composition of the raw materials and possible heat treatment. In the case of a fibrous material, the matrix substantially surrounds the grains or fibers or yarns, ie, coats them.

[0089] - In organic matrix composite materials such as the damping material according to the invention, the fiber reinforcement is bound by a thermosetting resin matrix. This is obtained by impregnating the fiber textile with a resin mixture comprising at least one or more prepolymers, a hardener and preferably a catalyst and a reinforcing agent or even a release agent, followed by a curing or hardening heat treatment to polymerize and crosslink the resin to form a thermosetting resin matrix.

[0090] - In a sintered ceramic body, for example in an impact-resistant plate, the ceramic grains are bound by a matrix obtained by sintering the preform. During the sintering process, they retain essentially the same shape and chemical properties as the initial charge. In a sintered ceramic body, the matrix and the grains together account for 100% of the product mass.

[0091] - "Bulk density" within the meaning of the present invention means a ratio equal to the mass of a product divided by the volume occupied by said product. It is usually determined by the Archimedean method. For example, the ISO 5017 standard specifies the conditions for such a measurement. This standard also makes it possible to measure the open porosity of ceramic materials.

[0092] - The porosity of the damping material is measured according to ASTM D3171-15.

[0093] In particular, the fiber reinforcement T f The volume fraction is the percentage between the apparent volume of the fiber and the apparent volume of the damping material. It is calculated using the following formula:

[0094]

[0095] in:

[0096] V 纤维 is the apparent volume of the fiber

[0097] M 纤维 The quality of the fiber

[0098] d 纤维 is the density of the fiber

[0099] V comp is the apparent volume of the damping material

[0100] M comp is the mass of the damping material

[0101] d comp is the density of the damping material

[0102] The mass of the composite material can be measured simply by weighing the damping material, the bulk density of which is determined by hydrostatic weighing according to the Archimedean principle.

[0103] Fiber mass can be determined after burning / decomposing the resin according to ASTM D3171-15. The bulk density of the fibers can then be determined by hydrostatic weighing.

[0104] -Measurement of the pore width of the damping material by analyzing images taken with a scanning electron microscope.

[0105] The SiO2 mass content of the silica yarns of the reinforcement can be measured by X-ray fluorescence.

[0106] The phase composition of the material constituting the impact-resistant plate is usually obtained by X-ray diffraction and Rietveld analysis. The elemental nitrogen (N) level in the sintered product is measured using a LECO analyzer (LECO TC 436DR; LECO CS 300). The values ​​are given in mass percentage. Crystalline phases, in particular nitrogen-containing crystalline phases or residual metals can be determined by X-ray diffraction and quantified by the Rietveld method.

[0107] - The Vickers hardness of a material can be measured with a standard diamond pyramid tip having a square base and a vertex angle between the faces equal to 136°. The imprint formed on the grain thus has the shape of a square; the two diagonals d1 and d2 of this square are measured with an optical device. The hardness is calculated from the force applied to the diamond tip and the average value d of d1 and d2 according to the following formula:

[0108]

[0109] The intensity and duration of application are also standardized. Suitable reference standards for ceramic materials are in particular ASTM C 1327:03 "Standard Test Method for VICKERS Indentation Hardness of Advanced Ceramics".

[0110] - The "median diameter" or "median size" of a group of particles, especially powders, is called D 50 Percentiles, ie, sizes that separate the particles into first and second populations of equal volume, these first and second populations comprising only particles having a size greater than or less than the median size, respectively.

[0111] The term "residues" refers to the components present in the raw material and still present in the sintered product obtained from this raw material.

[0112] Impurities are understood to mean unavoidable constituents which are introduced unintentionally and necessarily with the starting materials or result from reactions with those constituents. Impurities are not essential components but are merely tolerated.

[0113] - "Containing one / kind" or "comprising one / kind" should be understood to mean "comprising at least one / kind", unless otherwise specified.

[0114] Unless otherwise specified, all percentages in this specification are by mass.

[0115] Unless otherwise stated, all averages are arithmetic means.

[0116] Figure 1 A scanning electron microscope view of a cross section of a damping material according to Example 3 of the present invention is shown, wherein the reinforcement is composed of multiple sheets or layers (A, B, C, D) of fabric. The fabric is composed of silica fibers 1a and 1b combined into a single yarn. The silica fiber yarn is webbed with warp yarns (composed of fibers 1a) and weft yarns (composed of fibers 1b) substantially perpendicular to each other, as shown in FIG. Figure 1 The yarns are coated with a resin matrix 2. Porosity is present within the matrix and at the interface between the yarns in the form of pores 3 having an average width of about 3 microns.

[0117] Depending on the chosen configuration, the product according to the invention allows protection from different types of projectiles, such as bullets, shells, water / mines or elements launched by the detonation of explosives, such as bolts, nails (or IEDs for improvised explosive devices), and is generally an element of armor for vehicles or personal protection, fixed installations or communications equipment, usually in the form of a module (such as a plate).

[0118] Under the impact of a projectile, armor plates are known to shatter in order to absorb the impact energy of the projectile. When the latter have high penetration, it is necessary to use anti-impact plates placed between the threat and the impact energy dissipation plates. The main role of the anti-impact plates is to destroy the core of any projectile that comes into contact with the armor plates. The role of the dissipation plates is to dissipate the kinetic energy generated by the impact of the projectile by plastic deformation and to maintain the level of protection of the armor plates, which level is advantageously optimized by the protective wrapping material.

[0119] In the context of the present invention, the applicant has developed a new damping material for armor plates that can withstand threats such as 0.30-0.6-APM2 type, the damping material having a typical resistance of less than 20 kg / m 2 The result is a reduction in the overall weight of the gear for the same level of protection.

[0120] The individual stages of the method according to the invention are described in more detail below.

[0121] Preparation of fiber reinforcement

[0122] The fabric selected preferably has a 2D or UD weave. These weaves provide the best impact properties. In particular, a satin weave pattern is most preferred because fabrics in this pattern have fewer crossover points between warp and weft yarns, which can constitute potential weak points in the reinforcement. Silica fiber fabrics Q600 to Q660 supplied by Saint-Gobain Quartz are preferred because they have a density greater than 350 g / m 2 Weight.

[0123] Resin preparation

[0124] The resin mixture is selected from resins whose properties are preferably rheologically fluidized. In other words, its viscosity decreases when the shear stress increases within a certain range. The following ranges are particularly suitable for the implementation and production of the damping material according to the present invention. Preferably, the resin exhibits the following rheological properties, measured at 50°C using a plate / plate rheometer with a 20 mm diameter plate and a 1 mm air gap:

[0125] <![CDATA[Shear rate (s -1 )]]> Dynamic viscosity (Pa.s) 100 100 to 300 200 80 to 150 >400 and <500 <80

[0126] In order to obtain the best processing conditions for the composite damping material, in particular the best impregnation time, the resin preferably exhibits the following rheological properties, measured at 50°C by oscillating at a frequency of 2 Hz for 3 hours with a deformation of 0.1%, using a plate / plate rheometer with a 20 mm diameter plate and a 1 mm air gap. After 3 hours, the resin preferably exhibits a viscosity below 400 Pa.s. Preferably, the viscosity variation between 1 hour and 3 hours is less than 10%, preferably less than 5%.

[0127] Impregnation of reinforcements and formation of prepregs: When the reinforcement consists of several layers of textiles or pieces of fabric, the resin is usually too viscous at room temperature to impregnate the already stacked layers, so it is preferred to pre-impregnate each layer of textiles or each piece of fabric before stacking them.

[0128] The resin mixture is first heated to the processing temperature, from which its viscosity is preferably below 400 Pa.s, with a shear rate of 200s -1 , preferably heated to a temperature of about 50°C. A film of the resin mixture is deposited on a Teflon tray heated to the processing temperature described above. A reinforcement layer, preferably a fabric sheet, is deposited on the tray, and then a second resin film is deposited on the reinforcement layer. Slight pressure is applied to the prepreg to help impregnate the fabric. The prepreg is then placed in a sealed bag and, if necessary, stored in a refrigerator before being used in the next step after thawing to facilitate separation from the Teflon tray.

[0129] When the reinforcement consists of a plurality of layers, this first step may be repeated as many times as the number of reinforcement layers to be stacked, in order to form a stack of layers.

[0130] Preferably, the prepreg preform thus obtained is then placed in a vacuum bag, maintained at less than 1 bar, before curing.

[0131] Curing prepreg

[0132] The preform is then placed in an autoclave and subjected to temperature and pressure cycles.

[0133] During this curing step, a first temperature increase phase with a fluidization phase at 50-150° C. and a pressure rise to 2 bar makes it easier to eliminate potential offgassing and to distribute the resin as evenly as possible. The subsequent temperature increase to above the crosslinking temperature of the thermosetting resin enables the resin to polymerize and form a matrix encapsulating the reinforcement. The choice of resin in the viscosity range claimed advantageously makes it possible to obtain a damping material according to the invention with a controlled pore volume. The choice of a resin with the processability conditions as described above advantageously produces a damping material with a controlled pore width distribution.

[0134] Impact-resistant panels

[0135] The impact resistant plate of the armour plate according to the invention, if present, can in particular be obtained by a process comprising the following steps:

[0136] a) preparing a starting material, which comprises:

[0137] - a powder of at least one silicon carbide particle,

[0138] - a powder comprising silicon metal,

[0139] - optional powder of solid phase sintering additive,

[0140] b) forming the starting material into the form of a preform;

[0141] c) removing from the mold after solidification or drying;

[0142] d) optionally drying the preform, preferably to a residual moisture content of 0 to 0.5% by weight,

[0143] e) firing and sintering the preform in a nitrogen atmosphere, or if nitrogen is present in the raw material, in a non-oxidizing atmosphere, preferably at a temperature of 1300-1600° C., to obtain a sintered product constituting an impact-resistant plate.

[0144] In this method, a first initial silicon carbide powder is used, the median diameter of the particles of which is from 10 microns to 500 microns, and preferably from 50 to 300 microns. In some advantageous embodiments, a second silicon carbide powder is used, the median size of which is at least half of the median size of the first silicon carbide powder, and preferably has an average diameter of 1-5 microns.

[0145] In step b), the preform may be obtained by casting or pressing the raw material or the mixture into a mold with or without vibration.

[0146] During the curing process of step e), the nitrogen from the kiln reacts with some of the preform ingredients ("reactive sintering"), in particular with silicon metal or even aluminum metal (if present) by itself or in alloy with silicon, and also with calcined alumina or aluminum silicates such as clay, if these additives are present, to form a matrix and thus bind the grains of the ceramic body.

[0147] In the impact plate of the protective gear plate according to the invention, the ceramic grains, preferably grains of silicon carbide and / or boron, can be bonded by a matrix comprising a SiAlON phase without adding rare earth compounds and without resorting to high sintering temperatures (i.e., at temperatures above 1650° C.). In particular, a preform comprising only aluminum metal or in the form of an alloy with silicon is solidified at 1300-1500° C. in a nitrogen atmosphere for a sufficiently long time (>4 hours) to produce a sintered impact plate having a residual metal Al and Si content of less than 1% by mass.

[0148] The initial mixture may also contain a portion of alumina powder having a median diameter of 1 to 10 microns, which serves as a sintering agent.

[0149] The impact-resistant plate of the armour plate according to the invention is obtained in particular by the process as described above, preferably in the presence of a sintering additive chosen from carbon, boron, carbides of titanium or zirconium, or borides of zirconium or titanium, alone or in mixture.

[0150] In a particularly preferred embodiment, the product is obtained by the process as described above, wherein the sintering additive comprises or consists of boron carbide B4C. Sintering additives, often more simply referred to in this specification as "additives", refer to compounds generally known to allow and / or accelerate the kinetics of the sintering reaction.

[0151] In one embodiment, the starting material contains a binder and / or a lubricant and / or a surfactant. In one embodiment, the starting filler contains no binder.

[0152] The mixing is carried out in such a way as to obtain a good homogeneity of distribution of the various elements, the mixing time being adapted to achieve this result.

[0153] Preferably, the mixing of the initial reagents is carried out in a jar mill for a mixing time of more than 15 hours. A mixing time of 24 hours is very suitable. When the mixture is obtained, it can be atomized or granulated, for example by freeze granulation, to obtain particles that will be shaped (for example by pressing) to obtain a ceramic preform. Other forming techniques can be used, such as injection or grout casting. After forming, the preform can be machined.

[0154] The preform is then sintered. The sintering is performed in a nitrogen atmosphere.

[0155] Preferably, the silicon carbide powder has an elemental oxygen content of less than 2%, preferably less than 1.6%, preferably less than 1.4%, preferably less than 1.2%, preferably less than 1%, or even less than 0.7%, or even less than 0.5%, or even less than 0.3% by weight. In one embodiment, the oxygen elemental content of the silicon carbide powder can be reduced by any technique known to those skilled in the art, such as pickling, before use.

[0156] In one embodiment, the aluminum content of the feedstock is less than 1000 ppm, or even less than 500 ppm, or even less than 300 ppm, based on the weight of the feedstock.

[0157] The curing is carried out in a controlled atmosphere, preferably under nitrogen, to obtain a nitride intergranular phase.

[0158] The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention in any aspect described. Example

[0159] Each example, except for Example 1, in which the damping material was a commercially available composite material, was prepared by stacking 18 to 19 layers of resin-impregnated fabric (in order to work with a constant surface density), followed by heat treatment in an autoclave at 2 bar, with a step at 100° C., and then a crosslinking step, with a step at 160° C. for 3 hours, to obtain two damping panels with a surface area of ​​about 150×150 mm 2 The thickness was adjusted so that the final protective plates of all embodiments could be compared, with a thickness of 42 ± 1.5 kg / m 2 surface density.

[0160] For all examples, each damping plate was bonded to a SiC ceramic plate having a hardness greater than 10 GPa, measured according to ASTM C1327:03, and measuring 100x100x10 mm using Elantech 891-892 epoxy adhesive supplied by Elantas. 3 , to produce two final protective gear plates.

[0161] Example 1 (comparative)

[0162] In this embodiment, the impact energy dissipation plate is HB26 sold by DSM. Damping material, as cited in US 2013 / 0220106 A1.

[0163] Example 2 (Comparative)

[0164] The damping material in Comparative Example 2 is 500g / m 2 A fiber reinforcement in the form of a fabric made of The yarn is made of 20 silica fibers per single yarn, having a mass content of more than 99% SiO2 and an average equivalent diameter of 9 microns. The yarn with a linear density of 667 tex and a twist factor of Z3 is woven into a regular 8-piece satin weave with an undercut of 3 and vertical interlacing.

[0165] The matrix in Example 2 is obtained from an epoxy resin mixture comprising, by mass:

[0166] - 73% of a mixture of three different epoxy prepolymers (consisting of at least 70% of a prepolymer based on bisphenol A diglycidyl ether) having an average epoxy equivalent weight of 180 g,

[0167] -3% of dicyandiamide hardener in the form of micronized powder,

[0168] - 18% of a reinforcing agent in the form of a polyphenylene ether resin of the formula poly(2,6-dimethyl-1,4-phenylene ether), and

[0169] -6% by Modified imidazole catalysts are provided.

[0170] At 50°C for 200 s -1 The dynamic viscosity of the resin measured under the aforementioned conditions at a shear rate is 50 Pa.s.

[0171] Example 3 (Invention)

[0172] The matrix of Example 3 according to the invention differs from the previous formulation in that the epoxy prepolymer component has been modified by introducing about 50% by weight of an epoxy prepolymer obtained from cashew nut shell liquid. The new epoxy prepolymer is a blend of two resins with an average epoxy equivalent weight of 253 grams. The viscosity of the new mixture of the two epoxy resins measured under the same conditions as above is 100 Pa.s.

[0173] Example 4 (Comparative)

[0174] The difference between Comparative Example 4 and Example 3 is that every second warp and weft yarn is covered with a linear density of 500 tex. Linen fiber yarn is used instead, and the final reinforcement has 500g / m 2 Of the grammage, 43% of the mass consists of linen yarn and 57% of pure silica yarn.

[0175] Example 5 (Comparative)

[0176] Comparative Example 5 differs from Example 3 in that the proportion of the substrate is halved.

[0177] Example 6 (Comparative)

[0178] The difference between Comparative Example 6 and Example 3 is that, under the same conditions as above, the temperature is measured at 50°C for 200s. -1 At the shear rate, the viscosity of the resin is greater than 300 Pa.s and less than 500 Pa.s.

[0179] The impact properties of each final protective plate are summarized in Table 1 below. The impact performance of various protective plates was evaluated using the measurement of the dynamic deformation on the back side, which corresponds to the elastic deformation of the damping material during impact. Each protective plate was tested on a Sueur 40 plastic block with a Shore A hardness of 15-19, resisting a single impact shot fired at their center. Shots were fired at the SiC face of various protective plates configured independently. The test used a 30-06AP M2 threat, fired at a nominal speed of 878±9m / s at a distance of 15 meters. On each plastic block, a caliper was used to measure the depth and diameter of the deformation left by the dissipation plate during impact. These indicators characterize the dynamic deformation of the damping plate caused by impact. The arithmetic mean is calculated for each embodiment.

[0180] The presence of perforations "P" in Table 1 indicates a significant reduction in impact performance associated with lower damping capacity.

[0181] The results reported in Table 1 below show:

[0182] Compared with the commercial material of Comparative Example 1, the dissipation plate according to Example 3 of the present invention has a deformation depth reduced by one third and a deformation diameter increased by 20% at an equivalent surface density, showing a significantly higher ability to dissipate energy than the reference product on the market.

[0183] Compared with Examples 2 and 4, Example 3 shows that the materials of the reinforcement and the matrix selected according to the present invention have a higher energy dissipation capability.

[0184] Comparative Example 5 shows that a reinforcement volume fraction exceeding 80% degrades impact performance.

[0185] Comparative Example 6 shows that a damping material obtained with an overly viscous resin results in excessively high levels of porosity and thus reduced impact performance.

[0186] Table 1

[0187]

[0188]

[0189] NA = Not Applicable; NM = Not Measured; P = Permeate;

[0190] *At 50℃ and 200s- 1 Shearing is performed; BD = bulk density;

[0191] Of course, the invention is not limited to the embodiments described and shown by way of example. In particular, combinations of the various embodiments described are also within the scope of the invention.

Claims

1. An impact energy dissipation plate for ballistic protective gear, the dissipation plate consisting of a damping material, the damping material consisting of a fiber reinforcement bonded by an organic matrix, the reinforcement comprising inorganic fibers combined in the form of yarns, the matrix comprising a thermosetting resin, the damping material having the following characteristics: - the volume fraction of the fiber reinforcement of the damping material is 20% to 70%, and the remainder makes up to 100%, consisting of the matrix and pores; - the fiber reinforcement comprises at least 50% by volume of silica fiber yarns having a SiO2 mass content greater than 90%; The porosity of the damping material is between 2% and 10% by volume.

2. A dissipation panel according to the preceding claim, wherein the bulk density of the damping material is greater than 1.0 g / cm 3 And less than 2.0g / cm 3 .

3. Dissipator plate according to any one of the preceding claims, wherein the linear mass of the yarn is greater than or equal to 500 tex.

4. The dissipation plate according to any one of the preceding claims, wherein the average equivalent diameter of the silica fibers constituting the yarn is greater than or equal to 3 microns and / or less than or equal to 20 microns; 5. A dissipator panel according to any one of the preceding claims, wherein the fibre reinforcement consists essentially of the silica yarns.

6. A dissipator panel according to any one of the preceding claims, wherein the reinforcement is in the form of at least one layer of textile, preferably a woven fabric, consisting of a network of parallel warp yarns, wherein preferably weft yarns extend transversely across the network.

7. The dissipation panel according to the preceding claim, wherein the grammage of the textile layer is greater than or equal to 350 g / m 2 .

8. A dissipation plate according to any one of the preceding claims, wherein the matrix has pores between the resin and the yarns, the average width of the pores being from 10% to 100% of the average equivalent diameter of the fibers.

9. A dissipation panel according to any one of the preceding claims, wherein the matrix comprises an epoxy resin.

10. A ballistic armour panel comprising an impact energy dissipation panel according to any one of the preceding claims.

11. The protective gear plate according to any one of the preceding claims, further comprising an anti-impact plate, the anti-impact plate being composed of a material having a harderness greater than that of the damping material, the anti-impact plate having a thickness greater than 2 mm, and the anti-impact plate being placed in front of the dissipation plate relative to the impact direction.

12. The protective plate according to the preceding claim, wherein the material of the impact resistant plate has a Vickers hardness greater than 3 GPa.

13. The protective plate according to any one of the two preceding claims, wherein the bulk density of the impact resistant plate is less than 10 g / cm 3 .

14. The protector plate according to any one of claims 10 to 13, wherein the material of the impact resistant plate is a sintered material comprising grains of silicon carbide or boron carbide or a mixture of these two carbides.

15. The plate according to the preceding claim, wherein the grains of the sintered material are bonded by a matrix comprising a phase of silicon nitride Si3N4 and / or Si2ON2 and / or SiAlON.

16. The plate according to any one of claims 10 to 15, wherein the impact resistant plate is bonded to the energy dissipating plate by an adhesive selected from adhesives based on, for example, polyurethanes, epoxy polymers or thermoplastic polymers or elastomers.

17. A method for manufacturing a damping material or dissipation panel according to any one of the preceding claims, the method comprising the steps of: 1) preparing, preferably by weaving, at least one fiber layer comprising silica fiber yarns having a mass content greater than 90% SiO2, so as to obtain a reinforcement comprising at least 50% by volume of said yarns; 2) Prepare a mixture containing a thermosetting resin and use a 20 mm diameter plate / plate rheometer with a 1 mm air gap for 100 to 200 s -1 The viscosity of the thermosetting resin is 80 to 300 Pa.s when measured at 50°C at a shear rate; 3) impregnating the layers with the mixture and stacking the layers to obtain a preform, wherein the volume fraction of the fiber reinforcement of the damping material is 20% to 70%; 4) Curing the preform in an autoclave under controlled pressure and temperature to polymerize and crosslink the resin and form reinforcements bound by an organic matrix constituting the damping material.

18. Use of a dissipation panel according to claims 1 to 9 or a protective gear panel according to claims 10 to 16 for ballistic protection: - Anti-ballistic protection for people, said protection being selected from a bulletproof vest, a helmet or - ballistic protection of land, sea or air vehicles, or - ballistic protection of fixed installations, selected from buildings, walls or guardhouses; -Ballistic protection of radomes or detection or communication equipment.

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