EP2153159B9 - Method of manufacturing a composite, especially a bulletproof composite, and composite obtained - Google Patents

Abstract

The subject of the present invention is a method of manufacturing a composite (8) comprising a textile reinforcement (7) and a polymer matrix, especially a bulletproof composite. Said method characteristically comprises: a step of forming the textile reinforcement (7) by 2.5D weaving of first yarns with second yarns in a defined weave (A1/1), said second yarns being of a thermosetting polymer and said first yarns being high-performance yarns, so as to obtain an interlock fabric (7); and then a heat treatment during which said interlock fabric (7) is subjected to specified temperature and pressure conditions so as to melt said second yarns in order to form the polymer matrix, without impairing the first yarns.

Description

The present invention is in the technical field of composite materials for structuring applications, and more particularly for ballistic protection.

In ballistics, there are two types of impact, the low energy impact and the high energy impact. The kinetic energy developed by a given projectile is determined by the following relation: Ec = ½ mv ² (Joules) where m and v respectively correspond to the mass in Kg and the speed in m / s of said projectile.

The low energy impact is the impact of handgun and shotgun ammunition using non-perforating soft core bullets ranging in size from about 0.22 inches to 0.44 inches. The structures mainly used against this type of impact are called flexible protections. They are built of a succession of fabric layers, UD (UniDirectional) or nonwoven linked by seams in the form of checkerboard, rhombus or cross.

The high-energy impact corresponds to the impacts caused by ammunition of weapons of war, such as assault rifles Famas and Kalashnikov (caliber 5.56 mm, 7.62 mm, ...) or heavy machine guns (caliber 12.7 mm) ) Equipping aircraft, tanks, .... The so-called "perforating" balls have an internal warhead made of very hard and very dense metal (tungsten, hardened steel for example). Ballistic protection for weapons and piercing weapons ammunition requires the use of two types of hard protectors: monolayer shield consisting of a composite material alone and the bilayer shield consisting of a composite associated with a ceramic or composite plate and a steel plate. Ceramics are used in the field of ballistic protection for their low surface density compared to that of metal plates and their high hardness. The face of the ceramic plate exposed to an impact tends to fragment hard-core munitions with piercing bullets and reduce the kinetic energy associated with this impact. In this case, the composite material absorbs the kinetic energy by the deformation of its fibrous structure, ie its reinforcement, and intercepts the fragments.

The projectiles considered may be bullets, rockets or fragments of them. There are a multitude of projectiles (armored, perforating, expansive bullets, ...) which are differentiated by their mass, shape (ogive, spherical, ...), the material constituting them (lead, hardened steel ...) and in particular their speed of impact.

In the state of the art, composite materials for ballistic protection, and in particular for the protection of high energy impacts, are formed of the superposition of textile layers (knit, fabric, nonwoven, Uni Directional reinforcement, "Non Crimp Fabric" or NCF corresponding to non-wetted fabrics) optionally with inorganic layers, embedded in a matrix, such as an epoxy resin.

The matrix in these materials is incorporated by liquid means, for example by the process "RTM" (Resin Transfer Molding), or by gas. The textile reinforcements used can also be pre-impregnated, so-called prepegs.

In the case of two-dimensional textiles, during an impact, the shock wave propagates in the son by coupling at the crossing points, that is to say at the crossing points between the son. The energy is then dissipated in more wires and thus on a larger surface. Nevertheless, at the crossing points the waves are reflected and superimposed causing the elongation of the son forming the textile reinforcement until they break. Two-dimensional textile structures have a loss of load following an impact due to binding.

Thus, the textile reinforcements of the composite materials are oriented in a single direction in order to eliminate the cross points. These are unidirectional reinforcements in which the long fibers, arranged parallel to each other and in the same plane, are embedded in a matrix. It is also possible to orient the layers relative to each other according to different angles (0 °, 45 °, 90 °, ...) to improve the distribution and transfer of energy in the composite. For reasons of industrialization, the UD folds proposed in the composites on the market are oriented at 0 ° / 90 °.

We know the documents FR 2.610.951 and FR 2.819.804 describing intermediate woven reinforcements between a 2D reinforcement (the fibers are oriented in two directions) and 3D (the fibers are oriented in three directions) called by the skilled person "2,5D". The 2.5D fibrous reinforcements or reinforcements obtained are suitable for producing thin structures equivalent to a 2D stack, and having excellent delamination resistance such as 3D.

A composite is also known whose textile reinforcement comprises folds of fabric obtained according to an orthogonal weaving technique developed by the company 3Tex® and described in US Pat. EP 1.386.028 B1 . This weaving technique makes it possible to attenuate the delamination observed in laminated composites of 2D or UD plies, and to reduce the number of pleats required.

The document EP 0424216 A describes a method of manufacturing a composite material forming part of the state of the art with regard to the present invention.

Resistance to delamination is essential for shielding materials, especially in the case of multi-impact shots since the integrity of their structure is threatened. However, the delamination of shielding materials following an impact must not be eliminated. Indeed, a controlled delamination promotes the absorption of the kinetic energy due to an impact.

The subject of the present invention is a method for manufacturing a composite material making it possible to obtain a composite material having an improved delamination behavior, a weight per unit area lower than the density of the composites on the market with equivalent performance, less expensive and simpler to manufacture.

The present invention relates to a method for manufacturing a composite material, comprising a textile reinforcement and a polymer matrix, for ballistic protection, according to claim 1.

2.5D weaving refers to the weaving technique for obtaining fabrics called "warp interlock" or 2.5D, which can be performed on a conventional loom and to introduce son in the thickness of a multi-layered fabric. The warp interlock fabric is in the form of a multi-layer fabric whose connection between the layers is provided by the warp son. The weaving technique used is that of multichain weaving on a warp and weft loom in which the opening of the shed is unidirectional unlike weaving in 3 dimensions. Interlocks fabrics can be woven on all types of looms adapted to receive the layers of warp son required for the manufacture of said fabrics. The number of layers of warp threads is a function of the number of blades available on the loom and the fitting width of the chosen armor. 2.5D fabrics are suitable for the manufacture of thin structures because there are no inter-layer cavities such as in a three-dimensional (3D) fabric. This arrangement makes it possible to optimize the quantity of polymer matrix and promotes the production of lightweight composite materials.

A 2.5D fabric is a multilayer fabric having at least three layers or plies.

The temperature T ₀ of the heat treatment is preferably between the melting temperature of the second son T _f2 and the melting temperature of the first son T _f1 , T _f1 being greater than T _f2 , so that the first son are not altered .

Advantageously, the second son can be inserted in warp or weft, and this over the entire thickness, width and length of the interlock fabric, so that during said heat treatment the resulting molten polymer said second son impregnate heart said first son, and despite the sometimes significant thickness of the interlock fabric. Said first son are impregnated at the core and on the surface of the polymer matrix.

Advantageously, by weaving two groups of distinct threads, it is easy to adjust the quantity and the arrangement of the second threads in the 2.5D fabric so as to optimize the weight of the final polymer matrix in said composite material and the quality from the impregnation of the first sons to the heart.

The selected weave, the number of layers of the interlock fabric and the nature of the second threads are determined depending on the application of the composite material.

The second son may be multi-component yarns, gimped, fiber yarns and / or multi-filament yarns.

The first yarns are preferably monofilaments or multi-filament yarns in a high performance polymer.

The incorporation of the polymer matrix in the form of hot melt threads during the weaving step eliminates the step of incorporating the matrix by liquid or gaseous subsequent to the textile reinforcement forming step in the state of the technique. In addition, the quality of the impregnation is not with these techniques satisfactory for composite materials of large thickness, of the order for example of 20-25 mm for the composite materials forming the back layer of the composite assemblies for the shielding, several textile pleats are then impregnated individually and glued together. In the manufacturing method according to the present invention, the 2.5D weave making it possible to obtain an interlock fabric having a thickness of up to several tens of millimeters, these superposition and bonding stages of the various plies they are removed, which represents a considerable saving of time and money. During the heat treatment, the pressure exerted on the composite material under vacuum makes it possible to compact it and thus improve the impregnation of the first son.

The manufacturing process can be carried out continuously by arranging the means necessary for said heat treatment at the output of the 2.5D weaving step.

The Applicant has surprisingly found that the composite materials obtained according to the present invention for ballistic protection are very resistant to delamination, which is particularly advantageous in the case of multi-impact shots. A non-exclusive explanation is that said interlock fabric comprises first threads impregnated at the core and at the surface in the direction of its thickness which maintain the cohesion of the structure of said material under an impact, and thereby reduce the delamination effects that it is usually observed in the laminates of the state of the art. The delamination must, however, be retained so that the composite material after an impact does not fall apart completely. Advantageously, it has been observed with the composite material according to the present invention that the folds of the fibrous reinforcement delaminate progressively while sliding relative to one another in a controlled manner so that one fold adjacent to another fold is ultimately offset relative to to this other fold but always in solidarity with it. It is indeed possible to decompose the behavior of said composite material in three successive steps following impact. In a first step, the fibers at the periphery of the composite material are sheared and cut. Then, the shock wave propagates in the adjacent folds causing the elongation of the fibers until their breaks. The composite material generally behaves like a spring and the projectile sinks into the thickness of the composite material forming a tunnel. Finally, the inter-layer bonding yarns-that is, the warp yarns-block the delamination of the layers with respect to each other and thus make it possible to control the inter-layer slip. The composite material thus has excellent resistance to delamination while allowing the composite material to delaminate in a controlled manner, which is particularly advantageous in the case of a multi-impact shot.

In composite materials comprising a fibrous reinforcement consisting of several superposed distinct plies, secured by gluing for example, the delamination obtained is not controlled since the plies slide totally relative to each other, the composite material can totally disintegrate.

The folds of a 2.5D fabric are bound by the warp threads and not by the weft threads by definition. It is thus possible to exert prestressing on the warp or weft threads during the weaving operation in order to position the threads in a better working configuration as a function of the mechanical stress envisaged during the use of said composite material. . By way of example in the field of ballistic protection, the fact of exerting a prestressing on the weft threads, if possible equal to that exerted on the warp threads for a number of warp threads substantially equal to the number of threads weft, makes it possible to obtain a rear deformation of the iso-directional composite material. However, it is more difficult to control the stress exerted on the weft threads than on the warp threads.

Said manufacturing method makes it possible to obtain composite materials for ballistic protection, particularly in the following fields: protection of persons by means of vests, breastplates, helmets, and armor of land vehicles (tanks, combat vehicles, etc.), air (helicopters, transport planes ..) and marine (assault boats type cruiser and destroyer, aircraft carriers, submarines, ...). Depending on the nature, the quantity and the arrangement of said first and second wires, the composite material obtained can also be used for the manufacture of structural parts having improved mechanical performance, particularly in aeronautics and aerospace.

For applications such as the protection of persons, the composite materials obtained according to the present invention can be used alone, not used in composite assemblies, for protection against non-perforating bullets or against attacks with a blade.

High performance yarns are understood to mean yarns having a toughness substantially greater than 60 cN / Tex. This value makes it possible to distinguish the high-performance yarns from the conventional yarns used in particular in the field of clothing whose toughness is generally less than or equal to 60 cN / Tex. The first yarns are preferably selected from the following families of polymers, alone or as a mixture: aromatic polyamides such as para-aramid (poly-p-phenylene terephthalamide), meta-aramid (poly-m-phenylene isophthalamide), and para-aramid copolymers; aromatic polyimides; high performance polyesters, high density polyethylene (HDPE); polybenzoxazoles such as PBO (p-phenylene benzobisoxazole) and PIPD (polypyridobisimidasole); polybenzothiazoles; and glass, in particular of the S-2® brand marketed by AGY®.

Preferably, the first threads for ballistic protection are high density polyethylene yarns or S-2® brand glass fibers. The HDPE yarns have a density of less than 1 g / cm 3 ensuring their buoyancy, and in particular a high elastic modulus, high tenacity and good resistance to abrasion. In addition, S-2® glass fibers have a very high transverse compression modulus, unlike organic fibers, which gives them good ability to break up piercing projectiles.

The first HDPE yarns are based on the UHMWPE polymer ("Ultra High Molecular Weight PE"), and have a toughness greater than 2N / Tex, or more than 3N / Tex depending on the grades.

In a variant, the first threads have a toughness greater than 1 Newton / Tex.

These first son having very high resistance values to mechanical stresses, are preferred in textile reinforcements used in structuring applications.

In a variant, the second son are in one or more families of polymers: polypropylene, low density polyethylene, polyester and polyamide.

In one variant, the weave is of the diagonal type, in particular of the diagonal type 5-4.

The so-called diagonal armor ensures good dimensional stability to the textile reinforcement, especially during an impact. Generally speaking, all Weaving armors, especially of the diagonal type, favoring the floats and thus making it possible to minimize the points of connection between the layers of the interlock fabric, also known as crisscross points are preferred. Indeed, during an impact, the shock wave propagates in the son by coupling to the crossing points. The waves are reflected and superimposed causing the elongation of the first son forming the textile reinforcement until they break. Textile reinforcements having a limited number of cross points have better resistance to delamination and impact.

In a variant, the temperature T ₀ of the heat treatment is in the range [T _f2 + | T _f1 -T _f2 | / 2; T _f1 ], wherein the melting temperature of the second son T _f2 is less than the melting temperature of the first son T _f1 , so as to reduce the viscosity of the second son melted and improve the impregnation of the first son.

The applicant realized that the quality of the impregnation positively influenced the mechanical properties of the final composite material, and in particular the resistance to delamination.

In a variant, the manufacturing method according to the invention comprises an intermediate step, between the 2.5D weaving step and the heat treatment as described above, during which the reinforcement is superimposed in this order: textile obtained after said 2.5D weaving step, a first layer in a fusible polymer material, a second layer, preferably a para-aramid fabric layer, a third layer in a fusible polymer material a fourth layer, especially in a ceramic-based material; and in that during the heat treatment said first and third layers melt and bond the obtained composite material with said second and fourth layers so as to form a composite assembly for ballistic protection.

Said first and third layers are preferably a polyurethane film.

Said second layer is preferably a fabric, such as a fabric, based on para-aramid yarns. Said second layer is preferably calendered with a low density polyethylene film.

The fourth ceramic layer may be monolithic or formed of small tiles, flat or curved.

Said composite material forms, in the composite assembly for ballistic protection, in particular for shielding, the rear layer, that is to say the layer disposed in said assembly as close as possible to the element to be protected, the human body for example in the case of bulletproof vest.

The subject of the present invention is, according to a second aspect, a composite material obtained by implementing the manufacturing method described above, the 2,5 D woven fabric reinforcement comprising high performance yarns chosen from the families of organic polymers. following, alone or in admixture: aromatic polyamides such as para-aramid (poly-p-phenylene terephthalamide), meta-aramid (poly-m-phenylene isophthalamide), and para-aramid copolymers; aromatic polyimides; high performance polyesters, high density polyethylene (HDPE); polybenzoxazoles such as PBO (p-phenylene benzobisoxazole) and PIPD (polypyridobisimidasole); polybenzothiazoles; or among the following fibers: glass, in particular of the S-2® brand, carbon, alumina, silicon carbide, boron carbide.

Preferably, the first son forming the textile reinforcement for ballistic protection are high density polyethylene yarns or S-2® brand glass fibers.

In a variant, the polymer matrix is thermoplastic, and represents by weight less than 30%, preferably less than 20%, of the total basis weight of said composite material.

The insertion technique by weaving the polymer matrix into the interlock fabric makes it possible to optimize the quantity of matrix required. This arrangement makes it possible to lighten the mass per unit area of the composite material according to the invention compared to that of the composite materials of the state of the art to equal performance. The degree of reinforcement is thus very high, of the order of at least 70%, preferably at least of the order of 80%, and makes it possible to confer high mechanical performances on the structuring parts comprising said composite material.

In a variant, the polymer matrix is in one or more families of polymers: low density polyethylene, polypropylene, polyamide, polyethylene terephthalate, and especially in low density polyethylene.

In a variant, said textile reinforcement is typically formed of a single fold of fabric.

The method according to the invention advantageously makes it possible to obtain an interlock fabric in a single weaving operation having an adjustable weight / m ² and thickness as well as a polymer matrix disposed at heart by virtue of said second woven threads.

Thus, said composite material is not formed of the superposition of several folds, each fold being formed by an individual textile, but formed of a textile reinforcement comprising only one fold comprising a multi-layer fabric.

The object of the present invention is, according to a third aspect, a composite assembly for ballistic protection, the rear layer of which is formed of a composite material as described above.

For ballistic protection, particularly with regard to the protection against perforating bullets, the composite material according to the invention is used as a rear layer in a composite assembly, the front layer of said assembly preferably comprising a material having properties fragmentation of said balls. By back layer is meant that the composite material is disposed in said assembly so as to be closer to the element to be protected, for example oriented towards the interior of the cockpit of a helicopter in the case of shielding of air vehicles.

Said composite assembly is used for the shielding used in personal equipment and in particular in soft vests, bibs and helmets, or in the structuring panels forming the land vehicles (tanks, combat vehicles, etc ...), air (helicopters, have transport, etc ...) and sailors (aircraft carriers, etc ...).

In a variant, the composite assembly comprises from behind forwards: a composite material, a first layer made of a fusible polymer-based material, a second layer, preferably comprising a layer of para-aramid fabric, a third layer in a fusible polymer-based material, a fourth layer, especially in a ceramic-based material.

The fourth layer is arranged so as to directly face a possible impact when said composite assembly is used, and has the function of fragmenting the hard core munitions of the perforating bullets and reducing the impact kinetic energy.

In a variant, the composite material has a basis weight of the order of less than 11 000 g / m ² .

The incorporation of the polymer matrix being more easily controlled since it takes place during weaving, its quantity is optimized. Thus, the applicant has developed a composite material used as a back layer in a composite assembly for the shielding having a basis weight of the order of 10% less than the equivalent performance-based composite weights of composite materials. This provision has a considerable saving in energy especially for the protection of air vehicles, and preserves the wear of mechanical parts (shock absorbers, ...) of land vehicles.

• la figure 1 est une représentation schématique illustrant le principe de tissage 2,5D utilisée dans le cadre de la présente invention ;
• la figure 2 représente l'armure de base d'un exemple de tissu interlock selon la présente invention,
• la figure 3 représente le tableau de lecture de la structure du tissu interlock dont l'armure de base est représentée à la figure 2 ;
• la figure 4 est une coupe selon le sens chaîne du tissu interlock représentés aux figures 2 et 3.
• La figure 5 est une représentation schématique d'un ensemble composite pour la protection balistique comprenant un matériau composite dont les plis sont formés du tissu interlock décrit aux figures 2 à 4.

The present invention will be better understood on reading an exemplary embodiment of a composite material for ballistic protection, cited in a non-limiting manner, and illustrated in the following figures, appended hereto, in which:

• the figure 1 is a schematic representation illustrating the 2.5D weaving principle used in the context of the present invention;
• the figure 2 represents the basic armor of an exemplary interlock fabric according to the present invention,
• the figure 3 represents the reading chart of the interlock fabric structure whose basic armor is represented at figure 2 ;
• the figure 4 is a cut along the warp direction of the interlock fabric shown in Figures 2 and 3 .
• The figure 5 is a schematic representation of a composite assembly for ballistic protection comprising a composite material whose folds are formed of the interlock fabric described in FIGS. Figures 2 to 4 .

The loom 1 partially represented in the figure 1 5. When the vertical movement F of the frames 3, supporting the stringers in which are inserted the warp son, several chains 2 can be moved at the same time upwards to form a single crowd 4. The interlock fabric 5 is formed in this example of five layers 2 of warp and weft son 6. These layers 2 are themselves linked to each other by warp son. The weft threads 6 are inserted into the thickness e ₀ of the interlock fabric 5.

The basic tack A _1/1 shown in the figure 2 is a 5-4 diagonal with 3 out of 3. The off-set is the shift from one pick to another. In general, the number of layers of warp yarns is equal to the number of blades available on a loom divided by the fitting width of the armor chosen. The loom used in this embodiment, and not shown, comprises 24 blades. The blades are the frames supporting the rails. The interlock fabric 7, obtained by using the basic armor A _1/1 and shown in FIG. figure 4 thus comprises eight layers of CH1 to CH8 warp yarns woven with nine T1 to T9 yarns, including three yarns of woven chains per layer. The warp threads C ₁ to C ₃ correspond to the layer CH 1 of the interlock fabric 7 according to the table represented in FIG. figure 3 , and more particularly are woven according to the armor A _1/1 also represented in the figure 2 . The diagonal armors allow to have a height connection, here nine, much larger than the connection width, here three, if the uncheck divides the fitting height. This type of armor makes it possible to approach the structure of unidirectional textile reinforcements by minimizing the number of binding points. We notice at the figure 2 that the warp C ₁ passes over the T ₁ to T ₅ and then under the T ₆ to T ₉ . The chain wire C1 crosses only four picks, between T ₅ and T ₆ and T ₉ and T ₁ , on nine picks, which corresponds to two binding points or crossing points out of nine, ie about 22% tie points. . It is the same for the C2 and C3 chain son. The interlock fabric 7 thus comprises a low tying rate of the order of 22%. This binding rate makes it possible to ensure good dimensional stability to the interlock fabric 7 used as a textile reinforcement during an impact. In addition, it reduces the coupling at the crossing points of the shock waves following an impact and thus improves the resistance to delamination, particularly in the case of multi-impact shots.

To the figure 3 , the abbreviations LM and BM at the intersection of the boxes comprising the abbreviations CH1 to CH8 for the chain layers one to eight and the frame son T ₁ to T ₉ correspond to Lifting Mass and Lowering Mass, respectively. The term Lift Mass and Lower Mass respectively means lifting and lowering frames supporting the rails.

The figure 4 represents the interlock fabric 7 in a longitudinal section. The CH1 layer of said fabric 7 is formed of C1 to C3 chain son, and is bonded to the CH2 layer by these same warp son. There are two levels of frame n1 and n2 for the layer CH1 characteristics of double-sided fabrics weft. This evolution is repeated eight times in the direction of the thickness e ₁ of the fabric 7 since there are eight chains.

The ability of a wire to propagate a wave, is very important in the field of ballistic protection since it allows to dissipate the kinetic energy due to (x) shock (s) more or less quickly. The propagation velocity of a shock wave applied longitudinally on a wire is calculated by the following relation: VI = root (E / d) where E is the elastic modulus in Pa of the wire and the density in kg / m3 of said wire . Yarns with a velocity of more than 10,000 m / s are high-density polyethylene yarns; the para-aramid yarns and the glass yarns, in particular of the S-2® brand, have a very interesting propagation speed since they exceed 8000 m / s.

In this specific embodiment, the chain son C ₁ to C ₂₄ are the first son and are preferably high density polyethylene son, such as those marketed under the Spectra® brand by HoneyWell®. The first yarns respectively show toughness, tensile strength and an elastic modulus of 2.52 GPa, 2.31 GPa, and 62 GPa.

The second hot-melt yarns are inserted in weft, and preferably one yarn on four of the weft yarns T ₁ to T ₉ is a second hot-melt yarn. Preferably, the second yarns are of low density polyethylene, and have by way of example a tensile strength, an elongation at break and a Young's modulus respectively of 8 MPa, 200% and 170 MPa.

The titration of the first and second yarns is determined so that the interlock fabric 7 has a basis weight of the order of 3660 g / m ^2, including 2930 g / m ² for the first yarns formed by the HDPE yarns and 730g / m ² for the second son formed by hot melt son LDPE. The weight per second son is of the order of 20% of the total mass per unit area of the interlock fabric 7. The interlock fabric at the end of the loom has a thickness e1 of the order of 7 mm.

The composite assembly 14 shown in FIG. figure 5 is used for the shielding, that is to say in protection of piercing ammunition as described above. It comprises a composite material 8 formed in this order of three plies p1, p2 and p3 each comprising a layer of interlock fabric 7 and interposed with a hot melt film 9 for their adhesion. The composite material 8 forms the rear layer of the composite assembly 14. The composite assembly 14 also comprises, disposed on the fold p3: a first layer 10 in a fusible polymer-based material, a second layer 11 in a fabric made of calendered para-aramid with a LDPE film, a third layer 12 in a fusible polymer-based material, a fourth ceramic layer 13. Layers 9, 10 and 12 are in a thermofusible polyurethane film. The fourth layer 13 is formed of four alumina tiles arranged in staggered rows, not shown. The composite set 14 then undergoes a marouflage step of having on the set 14 a felt then a self-removing film and a not shown tarpaulin. Once said tarpaulin is sealed by means known in the state of the art, the evacuation of the assembly is performed and is intended to compact the assembly including the pleats p1 to p3 with the ceramic tiles. The assembly 14 is then subjected to a heat treatment having a treatment temperature of between 100 ° C. and 130 ° C., for at least two hours, preferably at least four hours, under a pressure greater than 5 bars, preferably equal to or greater than 10 bar. In this specific example, the treatment temperature is lower than the glass transition temperature of the high density polyethylene son in order not to degrade them.

The composite assembly 14 once cooked is removed from the mold. The composite material 8 has a surface density of the order of 11 000 g / m ² , the polymer matrix formed by the second melted wires represents 20% of the total basis weight of the composite material 8. The three plies p1 to p3 each formed a layer of interlock fabric 7 and interposed with the films 9 have a thickness of the order of 20 mm. The temperature T ₀ of the heat treatment is determined so as to obtain the fusion of the second son without altering the first son. Preferably, T ₀ is in the range [T _f2 + | T _f1 -T _f2 | / 2; T _f1 ], wherein the melting temperature of the second son T _f2 is less than the melting temperature of the first son T _f1 , so as to reduce the viscosity of the second son melted and improve the impregnation of the first son.

The layer 13 is the one disposed impacted first by an impact when the composite assembly 14 is used, the composite material 8 facing the element to be protected.

The composite assembly 14 was impacted according to MIL-PRF-46103E with a 12.7 mm bore (weight: 43 g). The speed of the ball must be of the order of 610 m / s according to the aforementioned standard. The impact formed a hole whose diameter is between 120 and 150 mm and the depth is between 20 and 25 mm. The composite assembly 14, having a thickness of 30 mm, stopped the ball. During the analysis of the composite assembly 14, after removing at least the layers 11 to 13, the impact left on the surface of the ply p3 on the composite material 8 is very clear compared to that left on the composite assembly of reference consisting of 48 folds UD superimposed in HDPE and glued with LDPE films. The large thickness of the textile reinforcement forming the ply p3, of the order of an interlock fabric layer 7, prevents it from being torn off with the ceramic layer 13 under the shock wave. In the composite reference assembly, the impacted surface, once the ceramic de-fragmentation layer has been removed, has exploded wires and highly deformed areas. In contrast, there is observed in the thickness of the composite material 8 a slight delamination between the plies p1, p2 and p3 sufficient to absorb the kinetic energy due to the impact but limited in order to minimize any dislocation of the composite material 8. The delamination behavior of the composite material 8 is improved by directly weaving an interlock fabric having a surface density of the order of 11 000 g / m ^{2, of} which 20% is formed by second hot melt threads. The back layer of the reference composite assembly has a surface density of the order of 10% greater than that of the composite material 8.

Claims (13)

1. A manufacturing process of composite material (8), comprising a textile reinforcement (7) and a polymer matrix, especially for ballisticproof protection, characterised in that it comprises:

   a)a step for forming the textile reinforcement (7) by 2.5D weaving of first yarns with second yarns according to a determined weave (A_1/1), said second yarns being made of thermofusible polymer and said first yarns being high-performance yarns to produce an interlock fabric (7),

   b)followed by thermal processing during which said interlock fabric (7) is subjected to temperature and pressure conditions determined so as to melt said second yarns to form the polymer matrix, without altering the first yarns.
2. The manufacturing process as claimed in Claim 1, characterised in that the first high-performance yarns have a tenacity of greater than 1 Newton/Tex.
3. The manufacturing process as claimed in either one of Claims 1 and 2, characterised in that the second yarns are in one or more families of the following polymers: polypropylene, low-density polyethylene, polyester and polyamide.
4. The manufacturing process as claimed in any one of Claims 1 to 3, characterised in that the weaving pattern is of diagonal type, especially of diagonal type 5-4 (A_1/1).
5. The manufacturing process as claimed in any one of Claims 1 to 4, characterised in that the temperature T₀ of the thermal processing is in the interval [T_f2+ |T_f1-T_f2|/2; T_f1], in which the melting temperature of the second yarns T_f2 is less than the melting temperature of the first yarns T_f1, so as to diminish the viscosity of the second melted yarns and improve impregnation of the first yarns.
6. The process as claimed in any one of Claims 1 to 5 for making a composite assembly (14) for ballisticproof protection, characterised in that it comprises an intermediate step, between the 2.5D weaving step and the thermal processing, during which the following are superposed in this order: the textile reinforcement obtained following said 2.5D weaving step (7), a first layer in a material based on meltable polymer (10), a second layer (11), preferably comprising a layer of para-aramide fabric, a third layer (12) in a material based on meltable polymer, a fourth layer (13), especially made of a ceramic-based material; and in that during thermal processing said first and third layers melt and connect the resulting composite material (8) to said second (11) and fourth (13) layers so as to form said ensemble (14).
7. A composite material (8) obtained by the manufacturing process as claimed in any one of Claims 1 to 5, characterised in that the textile reinforcement (7) comprises high-performance yarns selected from the families of the following organic polymers, individually or mixed: aromatic polyamides such as para-aramide (poly-p-phenylene terephtalamide), meta-aramide (poly-m-phenylene isophtalamide), and copolymers of para-aramides; aromatic polyimides; high-performance polyesters, high-density polyethylene (HDPE); polybenzoxazoles such as PBO (p-phenylene benzobisoxazole) and PIPD (polypyridobisimidasole); polybenzothiazoles; or fibreglass, especially of the trade mark S-2®.
8. The composite material (8) as claimed in Claim 7, characterised in that the polymer matrix is thermoplastic, and by weight represents less than 30%, preferably less than 20%, of the total surface mass of said composite material (8).
9. The composite material (8) as claimed in either one of Claims 7 and 8, characterised in that the polymer matrix is in one or more families of the following polymers: low-density polyethylene, polypropylene, polyamide, polyethylene terephthalate, and especially made of low-density polyethylene.
10. The composite material (8) as claimed in any one of Claims 7 to 9, characterised in that the textile reinforcement (7) is formed by a single fold of fabric (7).
11. A composite assembly (14) for ballisticproof protection whereof the rear layer is formed by a composite material (8) as claimed in any one of Claims 7 to 10.
12. The composite assembly (14) as claimed in Claim 11, characterised in that it comprises from back to front: a composite material (8), a first layer (10) in a material based on melting polymer, a second layer (11), preferably comprising a layer of para-axamide fabric, a third layer (12) made of a material based on melting polymer, a fourth layer (13), especially made of a ceramic-based material.
13. The composite assembly (14) as claimed in either one of Claims 11 and 12, characterised in that the composite material (8) has a surface mass of the order of or less than 11,000 g/m².

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