EP2732234A1

EP2732234A1 - Laminated composite for ballistic protection

Info

Publication number: EP2732234A1
Application number: EP12750487.6A
Authority: EP
Inventors: Hubert Simon; Dominique BURR; Muege Deniz YUEKSEK; Gabrielle MILLET; François Finck
Original assignee: Von Roll Isola France SA
Current assignee: Von Roll Isola France SA
Priority date: 2011-07-11
Filing date: 2012-07-10
Publication date: 2014-05-21
Anticipated expiration: 2032-07-10
Also published as: FR2977933A1; FR2977933B1; WO2013008178A1; EP2732234B1

Abstract

The present invention relates, generally, to the field of ballistic protection using panels for ballistic protection. More particularly, the present invention relates to a laminated hybrid composite (1a,1b) for ballistic protection, characterized in that it comprises a solid central thermoplastic polymer layer (2) which comprises, at least on one of the faces, a laminated thermoset material layer (3). The invention also relates to a process for manufacturing a composite according to the invention comprising the assembling, using an adhesive, of a solid thermoplastic polymer layer either sandwiched between two laminated thermoset material layers, or comprising, at least on one of the faces, a laminated thermoset material layer. The invention additionally relates to a bulletproof or antishrapnel protective device comprising a composite according to the invention. The invention also relates to the use of the composite according to the invention as bulletproof or antishrapnel protection.

Description

LAMINATED COMPOSITE FOR BALLISTIC PROTECTION

PRIORITY

The present application claims priority to U.S. Provisional Patent Application No.: 61/506,362 filed on July 11, 2011 and French Patent Application No.: FR 11/56296 filed July 11, 2011 ; The entire contents of each of these applications are incorporated herein by reference.

DESCRIPTION

Technical field

The present invention relates, generally, to the field of ballistic protection using bulletproof panels. More particularly, the present invention relates to a composite for ballistic protection and the manufacturing process thereof.

In the description below, the references between parentheses [ ] refer to the list of references presented at the end of the text.

Background a) Personal protection

Bulletproof materials intended for body protection are typically designed according to criteria of mechanical strength, ballistic properties, permissible residual deformation and/or lightness.

Aromatic polyamide (aramid) organic fibres, such as Kevlar®, have been widely used in bulletproof materials for their high ballistic properties. The drawback of bulletproof materials made of aramid fibres lies in the fact that although the projectile is stopped, the residual deformation at the point of impact (also referred to as "trauma") remains too large. One of the solutions would be to increase the number of layers of Kevlar® in the bulletproof material, but this would increase the weight and the thickness of the personal protection. To overcome this drawback, layers of materials made of thermoplastic organic fibres have been added to the layers of Kevlar® in the bulletproof materials as described in patent application GB 2 234 156 [1] and international application WO 2006/136323 [2] . Patent application GB 2 234 156 describes the use of polypropylene fibres, which make it possible to absorb the kinetic energy during the impact of the projectile.

However, adding additional layers to the bulletproof materials increases the thickness of the body protection.

One solution is proposed in patent application EP 1 847 796 [3], and describes the use of a laminated material, for body protection, produced from layers of Kevlar® impregnated with hollow thermoplastic microspheres containing gas, which exert resistance in the opposite direction to the projectile impact. b) Partitions, buildings

International application WO 2008/135685 [4] itself describes the use of a laminated composite in a partition panel for ballistic protection. A laminated composite is an assembly of one or more layers of at least two immiscible materials. In particular, this invention describes the assembling, within the panel, of at least one layer of impact-resistant aramid organic fibres, such as Kevlar®, and of at least one layer of glass fibres that make it possible to absorb the kinetic energy during the impact of the projectile. This bulletproof laminated composite is sold under the trade mark PARA-LITE®. c) Vehicle protection

International application WO 2008/109629 [5] describes the production of composite laminates for ballistic protection of vehicles. These laminates are composed of reinforcements based on glass fibres of less than 9 microns and of a thermosetting or thermoplastic or elastomeric resin. d) Conclusion regarding the background art However, there is not currently a material for ballistic protection on the market that is capable of simultaneously meeting the requirements of ballistic protection, mechanical strength, weight and limitation of the residual deformation at the point of impact (trauma). Description of the invention

Surprisingly, the inventors have discovered that the combination of a thermoplastic polymer and of a laminated thermoset material, in the form of a laminated composite of "sandwich" type, or simply in the form a thermoplastic polymer layer adhesively bonded, on one of its faces, to a laminated thermoset material layer, truly makes it possible to meet all of these requirements.

In the present text, the expression "thermoplastic polymer" is understood to mean a polymer that reversibly softens under the action of heat and hardens on cooling. Typically, thermoplastic polymers are made up of filiform linear macromolecules that are not joined together. They are especially characterized by their plastic formability when they are heated beyond their softening point.

In the present text, the expression "thermoset material" is understood to mean a material which, under the action of heat, gradually hardens to achieve an irreversible solid state. They are typically crosslinked materials (three-dimensional macromolecules). During the conversion thereof, the final structure of the macromolecules is obtained by irreversible chemical reactions. Once hardened, their shape can no longer be modified.

Thus, according to one aspect, a lightweight composite is proposed, possessing improved ballistic and mechanical properties, and having an advantageous limitation of the trauma. In the present text, the expression "residual deformation at the point of impact" or "trauma" is understood to mean the visible deformation of the material after the impact of the projectile on the opposite face to that of the impact face. It is measured in cm and is a result of the absorption of kinetic energy during the impact of the projectile on the material.

According to one aspect, the present invention proposes a laminated hybrid composite (la, lb) for ballistic protection, characterized in that it comprises a thermoplastic polymer layer (2) which comprises, at least on one of its faces, a laminated thermoset material layer (3), depending on the final application of the product or on the desired properties. Advantageously, the thermoplastic polymer layer (2) is a solid layer. In other words, the thermoplastic polymer layer (2) is advantageously not hollow, or does not contain voids, such as a honeycomb structure.

As used herein, the term "comprise" and variations of the term, such as " comprising" and "comprises," will be understood to imply the inclusion of other components or layers but not the exclusion of of other components or layers. However, it will be understood that the term "comprise" and variations of the term, such as " comprising" and "comprises," encompasses the variant "consist of and variations of that term, such as " consisting of " and " consists of.

According to one variant, and as illustrated in Figure 1A, a laminated hybrid composite (la) for ballistic protection is proposed, characterized in that it comprises a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3). Advantageously, there is provided a laminated hybrid composite (la) for ballistic protection, characterized in that it comprises one central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3), excluding other occurrences of a thermoplastic polymer layer and laminated thermoset material layers (in other words, the laminated hybrid composite (la) comprises only one central thermoplastic polymer layer (2) and two laminated thermoset material layers (3), in a sandwich configuration, the other components of the laminated hybrid composite (la) being different from a thermoplastic polymer layer and a laminated thermoset material layer). Advantageously, there is provided a laminated hybrid composite (la) for ballistic protection, characterized in that it consists of a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3). Advantageously, the central thermoplastic polymer layer (2) may be a solid layer. In other words, the central thermoplastic polymer layer (2) is advantageously not hollow, or does not contain voids, such as a honeycomb structure.

According to a second variant, and as illustrated in Figure IB, a laminated hybrid composite (lb) for ballistic protection is proposed, characterized in that it comprises a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3). Advantageously, there is provided a laminated hybrid composite (la) for ballistic protection, characterized in that it comprises one thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3), excluding other occurrences of a thermoplastic polymer layer and a laminated thermoset material layers (in other words, the laminated hybrid composite (lb) comprises only one central thermoplastic polymer layer (2) and one laminated thermoset material layer (3), adhesively bonded to each other, the other components of the laminated hybrid composite (la) being different from a thermoplastic polymer layer and a laminated thermoset material layer). Advantageously, there is provided a laminated hybrid composite (lb) for ballistic protection, characterized in that it consists of a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3). Advantageously, the thermoplastic polymer layer (2) may be a solid layer. In other words, the thermoplastic polymer layer (2) is advantageously not hollow, or does not contain voids, such as a honeycomb structure. Advantageously, there is provided a laminated hybrid composite (la, lb) for ballistic protection, characterized in that it comprises: a) a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3); wherein the central thermoplastic polymer layer (2) is a solid layer; or b) a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3); wherein the thermoplastic polymer layer (2) is a solid layer.

1. Thermoplastic polymer layer (2)

The thermoplastic polymer layer (2) may be produced from any thermoplastic polymer, copolymer or mixture of polymers. For example, it may be made up of polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyaramid, polyamide, polycarbonate, polyester, polyimide, or a mixture of at least two of these polymers.

Advantageously, the thermoplastic polymer layer (2) may be made up of polyethylene, polypropylene, polyamide, or a mixture of at least two of these polymers.

Advantageously, the thermoplastic polymer layer (2) may be made up of polyethylene or polypropylene, very particularly polyethylene.

Advantageously, there is provided a laminated hybrid composite (la, lb) for ballistic protection, characterized in that it comprises: a) a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3); wherein the central thermoplastic polymer layer (2) is a solid layer; or b) a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3); wherein the thermoplastic polymer layer (2) is a solid layer; wherein the thermoplastic polymer layer (2) may be made up of polyethylene, polypropylene, polyamide, or a mixture of at least two of these polymers. The thermoplastic polymer may be in the form of a ply, that is to say a unidirectional or two-dimensional arrangement of thermoplastic polymer yarns forming a flat surface. These yarns may be woven in certain cases in order to form a fabric. Thus, the thermoplastic polymer ply may be in the form of a woven or nonwoven thermoplastic polymer sheet. The weaving method may correspond, for example, to a weaving of taffeta weave or twill weave type. The thermoplastic polymer ply may be in the form of a symmetrical fabric (i.e. same number of polymer yarns in the weft and warp direction), or a unidirectional (UD) fabric, that is to say a fabric containing a different number of polymer yarns in the weft and in the warp.

The thermoplastic polymer ply may be pre-impregnated with an adhesive, enabling the good cohesion of the polymer yarns forming the ply. Such plies may, for example, be obtained from HPPE (High Performance Polyethylene) like for instance from Honeywell (Spectra®) and DSM (Dyneema®). By way of example, mention may be made of the Dyneema® BT10 and Dyneema® HB26 products, which are woven and laminated sheets of ultra-high-molecular- weight polyethylene (UHMWPE).

The thermoplastic polymer layer (2) may be produced from 5 to 200 thermoplastic polymer plies. In particular, these thermoplastic polymer plies may be stacked and compressed at high temperature in order to form a compact and uniform layer, the thickness and the ballistic properties of which are determined by the nature and the number of thermoplastic polymer plies used. Thus, the thermoplastic polymer layer (2) may be a solid layer. For example, the thermoplastic polymer layer (2) may be formed from 5 to 150, 5 to 100, 5 to 75, 5 to 50, 5 to 30, 5 to 20 or 5 to 15 thermoplastic polymer plies as a function of the desired ballistic properties and thickness (weight).

2. Laminated thermoset material layer (3) The laminated thermoset material layer (3) may be produced from a material having advantageous mechanical strength properties. For example, it may be produced from carbon fibres.

The laminated thermoset material layer (3) may comprise a stack of carbon fibre fabric plies (4), which plies may be pre-impregnated by a varnish in order to enable the formation of the laminated thermoset material layer (3) by hot pressing of said stack of carbon fibre fabric plies (4).

The expression "carbon fibre fabric ply" is understood in the present text to mean a two-dimensional arrangement of carbon fibres forming a fabric. Thus, the carbon fibre fabric plies may be in the form of woven carbon fibre sheets. The weaving method may correspond, for example, to a weaving of taffeta weave, twill weave or satin weave type, preferably taffeta weave or twill weave type. The carbon fibre fabric plies may or may not be in the form of a symmetrical fabric (i.e., same number of woven yarns in the weft and warp direction) or they may be in the form of a unidirectional (UD) fabric, that is to say a fabric containing a different number of woven yarns in the weft and in the warp.

Each yarn may comprise at least 3000 carbon fibrils and at most 48 000 carbon fibrils. For example, they may be carbon yarns containing 3000, 6000, 12 000, 24 000 or 48 000 carbon fibrils. The carbon fibre fabric plies may be symmetrical (i.e., containing the same number of carbon yarns/cm in the weft and warp direction), or asymmetrical, that is to say a fabric made from yarns containing a different number of carbon yarns/cm in the weft and in the warp.

Advantageously, the carbon fibre fabric plies (4) may be carbon fibre fabric plies conventionally used in aeronautics, namely carbon fibre fabric plies in which the yarns contain 3000 to 6000 carbon fibrils.

The laminated thermoset material layer (3) may comprise a stack of 5 to 30 carbon fibre fabric plies (4) (or 5 to 30 woven carbon fibre sheets) pre-impregnated by a varnish. In particular, these carbon fibre fabric plies (4) pre-impregnated by a varnish may be stacked and compressed at high temperature in order to form a laminated thermoset material layer (3), the thickness and the mechanical properties of which are determined by the nature and the number of carbon fibre fabric plies used. For example, the laminated thermoset material layer (3) may be formed from 5 to 30, 5 to 25, 5 to 20 or 5 to 15 carbon fibre fabric plies (4), as a function of the desired mechanical properties.

The pre-impregnating varnish may be any epoxy resin known in the field. The techniques for preparing pre-impregnated fabrics (or "prepregs") are well known in the field. Reference could be made, for example, to the following work: "Materiaux composites a matrice organique" [Composites containing an organic matrix], 1986, Gilbert Chretien, Publisher: Technique et Documentation, 11 rue Lavoisier, F-75384b Paris Cedex [6] .

For example, the impregnating varnish may contain a resin, a hardener, a catalyst and a solvent. The resin may be bisphenol A diglycidyl ether, a "novo lac" epoxy resin (such as bisphenol F, phenol-novolac resins, cresol-novolac resins, phenol- formaldehyde novolac resins or cresol-formaldehyde novolac resins), a resin based on tetraphenylolethane and triphenylolmethane glycidyl ethers, an epoxy resin based on aromatic amines (such as methylenediamine tetraglycidyl ether), an epoxy resin based on /?ara-aminophenol (such as /?ara-aminophenol triglycidyl ether), a cycloaromatic resin (such as 3,4-epoxycyclohexylmethyl or bis(2,3- epoxycyclopentyl)ether), a flexible epoxy resin (such as epoxy resins having a polyurethane backbone or that contain aliphatic chains), or an epoxy resin having improved fire behaviour (such as tetrabromobisphenol A diglycidyl ether). For example, a "standard" resin of the bisphenol A/epichlorohydrin derived liquid epoxy resin type may be used. An example is EPON® resin 828 from Momentive.

The hardener may be a catalytic hardener such as an aliphatic, alicyclic or aromatic primary or secondary amine. For example, it may be ethylenediamine, diethylenetriamine, triethylenetetramine, dimethylaminopropylamine, trimethylhexamethylenediamine, cyandiamine, N-aminoethylpiperazine, isophorone diamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, methylenedianiline or diaminodiphenylsulphone. The hardener may be a coreactive hardener such as an acid anhydride. Mention may be made, for example, of phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl nadic anhydride, tetrapropenyl succinic anhydride, trimellitic anhydride or pyromellitic anhydride.

For example, DDS (diaminodiphenylsulphone) from Sigma Aldrich may be used. The catalyst may be an imidazole, a phenol or a tertiary amine. It may be, for example, benzyldimethylamine, tris(dimethylaminomethyl)phenol, 2-ethyl-4- methylimidazole or the boron trifluoride/monoethylamine complex.

For example, the hardener HT 973® from Huntsman (boron trifluoride/ethylamine complex) may be used. The solvent may be, for example, methyl ethyl ketone, l-methoxy-2-propanol, or a mixture thereof. Advantageously, the solvent may be a 50/50 methyl ethyl ketone/ 1 -methoxy-2-propanol mixture.

For example, the methyl ethyl ketone from Celanese may be used.

The varnish may optionally contain a diluent, that is to say a liquid product typically added to epoxy resins in order to lower the viscosity thereof and enable easier processing. It may be, for example, a reactive or non-reactive diluent. Among the reactive diluents, mention may be made, for example, of n-butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, 1,4-butanediol diglycidyl ether or l,2-epoxy-4-(epoxyethyl)cyclohexane. Among the non-reactive diluents, mention may be made, for example, of dibutyl phthalate and benzyl and furfuryl alcohols.

3. Laminated hybrid composite (la, lb) The laminated hybrid composite (la) may comprise a central thermoplastic polymer layer (2) as defined above, sandwiched between two laminated thermoset material layers (3) as defined above. Advantageously, the laminated hybrid composite (la) for ballistic protection, may comprise one central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3), excluding other occurrences of a thermoplastic polymer layer and laminated thermoset material layers (in other words, the laminated hybrid composite (la) comprises only one central thermoplastic polymer layer (2) and two laminated thermoset material layers (3), in a sandwich configuration, the other components of the laminated hybrid composite (la) being different from a thermoplastic polymer layer and a laminated thermoset material layer). Advantageously, the laminated hybrid composite (la) for ballistic protection consists of a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3). According to another variant, the laminated hybrid composite (lb) may comprise a thermoplastic polymer layer (2) as defined above, adhesively bonded on one of its faces to a laminated thermoset material layer (3) as defined above. Advantageously, the laminated hybrid composite (lb) for ballistic protection comprises one thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3), excluding other occurrences of a thermoplastic polymer layer and a laminated thermoset material layers (in other words, the laminated hybrid composite (lb) comprises only one central thermoplastic polymer layer (2) and one laminated thermoset material layer (3), adhesively bonded to each other, the other components of the laminated hybrid composite (la) being different from a thermoplastic polymer layer and a laminated thermoset material layer). Advantageously, the laminated hybrid composite (lb) for ballistic protection consists of a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3).

Advantageously, for each variant (la) and (lb) of the laminated hybrid composite, the thermoplastic polymer layer (2) (whether it be central as in variant (la) or not as in variant (lb)) may be a solid layer. In other words, the thermoplastic polymer layer (2) is advantageously not hollow, or does not contain voids, such as a honeycomb structure.

Advantageously, for each variant (la) and (lb) of the laminated hybrid composite, the laminated thermoset material layers (3) may be identical or different. In particular, they may each contain:

- the same number or a different number of carbon fibre fabric plies (4),

- the same type or a different type of carbon fibre fabric plies (4) (i.e., symmetrical or asymmetrical carbon fibre plies), - carbon fibre fabric plies (4) having the same type or a different type of weaving method (i.e. taffeta weave, twill weave or satin weave), and/or

- carbon fibre fabric plies (4), the fibres of which contain the same number or a different number of carbon yarns (i.e., 3000, 6000, 12 000, 24 000 or 48 000 carbon fibrils). Advantageously, the laminated hybrid composite (la) is symmetrical, that is to say that the two laminated thermoset material layers (3) constituting it are identical. This renders the use of the laminated hybrid composite (la) as bulletproof or antishrapnel protection easier and safer (i.e. the user can equally well use one or the other face of the laminated hybrid composite panel (la) towards the source of projectiles or shrapnel when it is a symmetrical panel).

In the present text, the expression "material for ballistic protection" is understood to mean a material suitable for immobilizing a bullet fired by a firearm, such as for example for a small calibre (handgun) the 357 or 44 Magnum, or for a larger calibre (assault rifle) the AK47 (7.62x39) or Nato Ball (7.62x51), or other weapon with a 0.3 FSP calibre, in tests like for instance according to the norm MIL STD 662F. When the laminated hybrid composite (la) is asymmetrical (that is to say that the two laminated thermoset material layers (3) constituting it are different, for example, in terms of the number of carbon fibre fabric plies (4) of which they are constituted), one face of the laminated hybrid composite (la) is advantageously marked in order to identify that which is intended to be exposed to the source of projectiles or shrapnel.

The laminated hybrid composite (la) may be assembled by adhesively bonding a laminated thermoset material layer (3) to each of the two surfaces of the central thermoplastic polymer layer (2), so that said central thermoplastic polymer layer (2) is sandwiched between two laminated thermoset material layers (3). In another variant, the laminated hybrid composite (lb) may be assembled by adhesively bonding one laminated thermoset material layer (3) to one of the two surfaces of the thermoplastic polymer layer (2). Advantageously, in each variant (la) and (lb), the thermoplastic polymer layer (2) may be a solid layer. The adhesive used may be any adhesive capable of providing an assembly that is solid, durable and resistant to delamination. For example, it may be an epoxy adhesive or a silicone adhesive. Advantageously, it could be an epoxy adhesive, for example such as that defined in the various embodiments described above for the pre-impregnating varnish. Mention could be made, for example, of the epoxy adhesive of Araldite®, Lopox®, Lekutherm® or Eporex/Uranox® type.

For example, the Araldite® 2011 adhesive may be used.

Advantageously, the surface of the laminated thermoset material layer (3) and/or of the thermoplastic polymer layer (2) could be pretreated in order to increase the roughness thereof. This may be accomplished, for example, via mechanical means such as sanding with sandpaper. The roughness may also be introduced during the preparation of the laminated thermoset material layers (3) and/or the thermoplastic polymer layer (2): in the press used, the element in contact with the outer surface of the laminated thermoset material layer (3) and/or the thermoplastic polymer layer (2) may contain, on its surface, a pattern in relief that makes it possible to imprint/etch this pattern into said layers (2) and/or (3). This increased roughness makes it possible to provide bonding that is more resistant to delamination.

4. Properties of the laminated hybrid composite (la, lb)

The properties of a hybrid composite according to the invention are summarized below:

Ballistic properties

Advantageously, the laminated hybrid composite (la, lb) makes it possible to attain a minimum ballistic limit V50 of 555 m/s at 0 degree of obliquity according to the MIL STD 662 standard with a 0.3 FSP calibre. In particular, when the laminated hybrid composite (la, lb) according to the invention is tested according to the aforementioned standard, no perforation is observed.

Furthermore, when the laminated hybrid composite (la, lb) according to the invention is tested according to the NIJ 0101.06 standard with for instance ammunition of 7.62x51 NB or 7.62x39 MSC AK47 type, the residual deformation at the point of impact ("trauma") is between 0 and 3 cm.

The deformation or trauma is generally evaluated using a material used for modelling known as plastilin. For example, the NIJ 0101.06 standard describes this method.

Mechanical properties, at 23°C

- Flexural strength or tensile strength in perpendicular flexion (measured according to ISO 178):

Advantageously, the laminated hybrid composite (la, lb) according to the invention has a perpendicular flexural strength from 50 to 130 MPa, measured according to the ISO 178 standard. - Flexural modulus of elasticity in perpendicular flexion:

Advantageously, the laminated hybrid composite (la, lb) according to the invention has a flexural modulus of elasticity, in perpendicular flexion, between 20 000 MPa and 30 000 MPa, measured according to the ISO 178 standard.

Physical properties:

Advantageously, the laminated hybrid composite (la, lb) according to the invention has a density between 0.8 g/cm³ and 1.5 g/cm³ (measured according to the ISO 1183 standard). Preferably, the laminated hybrid composite (la, lb) according to the invention weighs between 10 and 13 kg per square metre for a thickness of 10 to 12 mm for a panel tested according to MIL STD 662 with a 0.3 FSP fragment projectile. Other thicknesses and weights of panels may be needed for protection against other threats.

- Absorption of water (after 24 h in water at 23°C): < 0.1% (measured according to the ISO 62 standard).

5. Process for preparing the laminated hybrid composite (la, lb)

According to another object of the invention, a process is provided for manufacturing a laminated hybrid composite (la) comprising the assembling, using an adhesive, of a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3). Advantageously, the central thermoplastic polymer layer (2) may be a solid layer.

According to another variant, a process is provided for manufacturing a laminated hybrid composite (lb) comprising the assembling, using an adhesive, of a thermoplastic polymer layer (2) with a laminated thermoset material layer (3). Advantageously, the thermoplastic polymer layer (2) may be a solid layer. It is understood that all the variants presented above for the laminated hybrid composite, and its components (e.g., thermoplastic polymer layer (2), laminated thermoset material layers (3), adhesive, etc.) are applicable mutadis mutandis to the process of the invention, even though they are not explicitly reiterated here. Advantageously, there is provided a process for manufacturing a composite (lb) as defined above and herein, comprising the assembling, using an adhesive, of a thermoplastic polymer layer (2) with a laminated thermoset material layer (3); wherein the thermoplastic polymer layer (2) is a solid layer. Advantageously, the thermoplastic polymer layer (2) is made up of polyethylene, polypropylene, , polyamide, or a mixture of at least two of these polymers.

The adhesive is as defined in any one of the embodiments described in section "3. Laminated hybrid composite (la, lb)" above. For example, it may be an epoxy or silicone adhesive, preferably an epoxy adhesive.

Advantageously, the thermoplastic polymer layer (2) may be obtained by stacking thermoplastic polymer plies under a pressure of between 2 MP a (20 bar) and 20 MPa (200 bar) at a temperature between 80°C and 160°C. The thermoplastic polymer plies are as defined in any one of the embodiments described in section "1. Thermoplastic polymer layer (2)" above. For example, they may be polyethylene or polypropylene plies, advantageously polyethylene plies. Advantageously, the thermoplastic polymer layer (2) may be obtained by stacking from 5 to 200 thermoplastic polymer plies, as defined previously. For example, the thermoplastic polymer layer (2) may be formed from 5 to 150, 5 to 100, 5 to 75, 5 to 50, 5 to 30, 5 to 20 or 5 to 15 thermoplastic polymer plies, as a function of the desired ballistic properties and thickness (weight). Advantageously, the temperature is maintained at a value below the glass transition temperature of the thermoplastic polymer. For example, when the thermoplastic polymer plies are polyethylene plies, the process for preparing the thermoplastic polymer layer (2) may be carried out by stacking polyethylene plies under a pressure of between 2 MPa (20 bar) and 20 MPa (200 bar) at a temperature between 120°C and 130°C. When the thermoplastic polymer plies are polypropylene plies, the process for preparing the thermoplastic polymer layer (2) may be carried out by stacking polypropylene plies under a pressure of between 2 MPa (20 bar) and 20 MPa (200 bar) at a temperature between 145°C and 155°C. A person skilled in the art will know how to define the temperature range to be used as a function of the thermoplastic polymer used.

Advantageously, the laminated thermoset material layer (3) may be obtained by stacking at least 5 carbon fibre fabric plies (4) that are pre-impregnated with a varnish, under a pressure of between 2 MPa (20 bar) and 5 MPa (50 bar) at a temperature between 140°C and 200°C.

The varnish is as defined in any one of the embodiments described in section "2. Laminated thermoset material layer (3)" above. For example, it may be an epoxy resin as defined previously. Advantageously, the laminated thermoset material layer (3) may be formed from 5 to 30, 5 to 25, 5 to 20 or 5 to 15 carbon fibre fabric plies (4), as a function of the desired mechanical properties and thickness (weight).

Reference may be made to Figure 2, which illustrates one embodiment of the process for preparing a laminated thermoset material layer (3) according to the invention. For example, the varnish may be premixed in a tank (5), and a carbon fibre fabric ply (4) may be dipped into this varnish, before being passed into an oven (6) (or drying tower). The main role of the oven (6) is advantageously to evaporate the solvent, so as to avoid obtaining a tacky carbon fibre fabric ply (4). Advantageously, the oven (6) is maintained at a temperature so as to evaporate almost all of the solvent contained in the carbon fibre fabric ply (4) pre- impregnated with the varnish. A person skilled in the art will know how to define the temperature range to be used as a function of the solvent contained in the varnish. For example, when the varnish contains a 50/50 methyl ethyl ketone/1- methoxy-2-propanol mixture, the oven (6) may be maintained at a temperature from 150°C to 200°C.

Thus, the laminated thermoset material layer (3) may be obtained via a process in which the carbon fibre fabric plies (4) pre-impregnated with a varnish are obtained by dipping said carbon fibre fabric plies (4) into an impregnating varnish containing a resin, a hardener, a catalyst and a solvent; followed by evaporation of said solvent.

The laminated hybrid composite (la) may be assembled by adhesively bonding a laminated thermoset material layer (3) to each of the two surfaces of the central thermoplastic polymer layer (2), so that said central thermoplastic polymer layer (2) is sandwiched between two laminated thermoset material layers (3). According to another variant, the laminated hybrid composite (lb) may be assembled by adhesively bonding a laminated thermoset material layer (3) to one of the two surfaces of the thermoplastic polymer layer (2). Advantageously, in variants (la) and (lb), the thermoplastic polymer layer (2) may be a solid layer. The adhesive used may be any adhesive capable of providing an assembly that is solid, durable and resistant to delamination. For example, it may be an epoxy adhesive or a silicone adhesive. Advantageously, it could be an epoxy adhesive, for example such as that defined in the various embodiments described above for the pre- impregnating varnish.

6. Applications and uses

According to another aspect, a bulletproof or antishrapnel protective device is provided that comprises a laminated hybrid composite (la, lb) as defined previously.

According to another aspect, the invention relates to the use of a laminated hybrid composite (la, lb) as defined previously as bulletproof or antishrapnel protection.

The laminated hybrid composite (la, lb) according to the invention may find an application in any device for ballistic protection. For example, it may be applied to buildings, civilian or military vehicles, shelters temporary or permanent shelters intended for police or military forces, or personal protection such as bulletproof or antishrapnel helmets, shields, vests or inserts/chest protectors.

The laminated hybrid composite (la, lb) according to the invention may therefore be in various forms, depending on the envisaged application. For example, it may be in the form of a panel having a thickness between 1.5 and 100 cm, of a moulded article (for example for a helmet) or of an insert (for application in bulletproof or antishrapnel vests).

Advantageously, the laminated hybrid composite (la, lb) according to the invention is particularly suitable for the manufacture of a safety zone in the form of an armoured booth of the type of that presented in Figure 3 and enabling weapons to be discharged in complete safety in shooting ranges and police stations and armouries.

Preferably, bullet traps may be placed in these booths which conform to category 1 (357 and 44 Mag handguns) and category 2 (12 calibre rifle) as defined by the BAIPN (Bureau des Affaires Immobilizes de la Police Nationale) [French Police Authorities]. Figure 3 shows a bulletproof booth 16, comprising several panels 1 in accordance with any one of the embodiments of the laminated hybrid composite (la, lb) of the invention and preferably in accordance with the embodiments described in Figure 1. The panel 1 may also be used as separating partitions in a building. This is directly related to the high mechanical properties that exhibit the panels according to the present invention.

Another application relates to inserts for personal protection. Composite parts for ballistic protection are generally inserted into textile materials of the vest type in order to give protection to the individual and to their vital organs (for example chest protection). The laminated hybrid composite according to the present invention makes it possible to advantageously reduce the trauma.

Another application example relates to panels for ballistic protection in order to protect vehicles and their passengers. The present invention makes it possible to produce bodywork parts that have high mechanical strengths without being combined with metal and metal bodywork parts, and while guaranteeing ballistic protection, having a weight much lower than the equivalent protective parts which are generally combinations of composites with metal.

7. Advantages The laminated hybrid composite (la, lb) according to the invention takes advantage of the advantageous mechanical properties of carbon fibres, and of the ballistic properties of thermoplastic polymers such as polyethylene or polypropylene.

This advantageous combination of these two materials having very different physical and chemical properties makes it possible to obtain, surprisingly, a hybrid composite meeting all of the four main constraints required in the field of ballistic protection, namely: - a low weight, a good mechanical strength,

- improved ballistic properties, and a limited trauma (< 3 cm), these all being in the complete absence of perforation of the material by the projectiles, even with multiple impacts.

For the first time, to the knowledge of the inventors, the combination of a thermoset material and of a thermoplastic material is proposed in order to provide a solution that is particularly suitable for the aforementioned constraints. The thermoplastic material makes it possible to reduce the density of the composite while increasing its ballistic performance, by enabling, in particular, the composite to absorb more energy during the impact of the bullet. The thermoset material itself also contributes to the lightening of the structure (since it is constituted of carbon fibres) and also gives the composite according to the invention high mechanical strength properties, in particular a flexural modulus of elasticity, in perpendicular flexion, between 20 000 MPa and 30 000 MPa, typically greater than 25 000 MPa (measured according to the ISO 178 standard).

The combination of the thermoplastic polymer layer (2) and of the laminated thermoset material layers (3) contributes to lightening the bulletproof or antishrapnel panel. This laminated bulletproof or antishrapnel structure thus makes it possible to progressively absorb the kinetic energy of the projectile in order to contribute to the progressive slowdown thereof within the panel thus preventing a risk of the projectile ricocheting.

A panel according to the invention for partitions or vehicles is two to three times lighter than a conventional armour based on steel or concrete having a similar level of protection. Other features and advantages will also become apparent to a person skilled in the art on reading the description which is given below and the examples below, given by way of illustration and in no way limiting, with reference to the appended figures. Brief description of the figures

Figure 1A represents a cross section of a laminated hybrid composite (la) for ballistic protection according to one variant of the invention;

Figure IB represents a cross section of a laminated hybrid composite (lb) for ballistic protection according to one variant of the invention; - Figure 2 represents an example of an implementation device for preparing prepreg carbon fibre fabric plies (4) according to the invention;

Figure 3 shows a bulletproof booth formed of several panels of laminated hybrid composite (la, lb) according to the invention, this booth forming a secured zone for enabling a person in the booth to handle firearms.

EXAMPLES

The bulletproof or antishrapnel laminated hybrid composite according to the present invention and the preparation thereof may be understood with the aid of the following examples, which illustrate certain methods via which this composite may be prepared or used. It will be noted, however, that these examples are given by way of illustration and are not meant to be limiting.

EXAMPLE 1

I. Process for manufacturing a laminated hybrid composite (la) according to the invention The process for manufacturing the composite (la) is carried out in three independent steps.

• First step: formation of the central thermoplastic polymer layer (2)

The thermoplastic polymer used is UHMWPE Dyneema® ultra-performance polyethylene. In particular, woven sheets of ultra-performance polyethylene, sold under the trade mark Dyneema® BT 10, are used.

50 plies of Dyneema® BT 10 polyethylene sold by DSM are stacked and pressed together at a temperature of 130°C. In this example, the operations were carried out on a press sold by Secmhy. The press is cooled for 5 minutes to a temperature of 30°C before removing the polyethylene layer from the mould.

The number of plies of Dyneema® BT 10 polyethylene determines the final thickness of the central thermoplastic polymer layer (2), and of the laminated hybrid composite (la). In this example, the final thickness of the central thermoplastic polymer layer (2) is 9.5 mm. The central thermoplastic polymer layer (2) is a solid layer.

• Second step: formation of the laminated thermoset material layer (3)

Carbon fibre fabric plies (4) sold under the name 3K carbon by Porcher Industrie are used. The formation of the laminated thermoset material layers (3) is similar to that of the central thermoplastic polymer layer (2), and requires a preliminary step of impregnating the carbon fibre fabric plies with a varnish.

The prepreg carbon fibre fabric plies are obtained by dipping carbon fibre fabric plies into an impregnating varnish containing a resin, a hardener, a catalyst and a solvent. In this example, the resin is EPON® resin 828, the hardener is DDS (diaminodiphenylsulphone), and the catalyst is the boron trifluoride/ethylamine complex.

The solvent used is a mixture of methyl ethyl ketone and l-methoxy-2-propanol (50/50).

The solvent is then evaporated by drying the prepreg carbon fibre fabric plies in an oven set at 150°C to 200°C for 5 to 10 minutes.

Next, ten prepreg carbon fibre fabric plies are pressed together under 25 bar for 1.5 hours at a temperature of 185°C.

• Third step: assembly of the central thermoplastic polymer layer (2) and of two laminated thermos et material layers (3)

The laminated hybrid composite (la) is assembled using a two-part epoxy adhesive, comprising an epoxy resin and a hardener, sold under the trade mark Araldite®.

The adhesive is applied uniformly over the whole of the two outer faces of the central thermoplastic polymer layer (2). Next, the two laminated thermoset material layers (3) are affixed to each side of the central thermoplastic polymer layer (2). The assembly is then placed in a press (e.g. a Sechmy press) under 5 bars for a duration of 4 hours at a temperature of 60°C. II. Mechanical tests

Flexural tests

The flexural strength and the flexural modulus of elasticity, in perpendicular flexion, of the composite described previously are determined according to the ISO 178 standard.

The flexural test results in a value of the flexural strength equal to 100 MPa and a value of the flexural modulus of elasticity, in perpendicular flexion, equal to 25 000 MPa.

III. Ballistic tests

1. Tests according to the MIL STD 662 standard

The composite described previously was tested according to the MIL STD 662 standard with a 0.3 FSP type projectile.

2. Other ballistic tests performed

Other tests were performed with other ammunition of 7.62x51 NB or 7.62x39 MSC AK47 type. The average residual deformation at the point of impact ("trauma") on a sample without carbon is 28 to 31 mm, which should be compared with a deformation of 24 to 25 mm with carbon (reduction of 17% approximately). List of references

[1] GB 2 234 156 [2] WO 2006/136323 [3] EP 1 847 796 [4] WO 2008/135685 [5] WO 2008/109629

[6] Materiaux composites a matrice organique [Composites containing an organic matrix], 1986, Gilbert Chretien, Publisher: Technique et Documentation, 11 rue Lavoisier, F-75384 Paris Cedex. [7] J. Rodriguez et al., "High strain rate properties of aramid and polyethylene woven fabric composites", Composites Part B: Engineering, 1996, Volume 27, Issue 2, pages 147-154.

[8] F. Larsson and L. Svensson, "Carbon, polyethylene and PBO hybrid fibre composites for structural lightweight armour", Composites Part A: Applied Science and Manufacturing, 2002, Volume 33, Issue 2, pages 221-231.

[9] CP. Koch et al., "Response of a high-strength flexible laminate to dynamic tension", International Journal of Impact Engineering, 2008, Volume 35, Issue 6, pages 559-568.

Claims

Laminated hybrid composite (la, lb) for ballistic protection, characterized in that it comprises: a. a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3); wherein the central thermoplastic polymer layer (2) is a solid layer; or b. a thermoplastic polymer layer (2) adhesively bonded, on one of its faces, to a laminated thermoset material layer (3); wherein the thermoplastic polymer layer (2) is a solid layer; wherein the thermoplastic polymer layer (2) may be made up of polyethylene, polypropylene, polyamide, or a mixture of at least two of these polymers.

Composite according to Claim 1 , in which said central layer (2) is a stack of 5 to 200 plies of thermoplastic polymer.

Composite according to Claim 2, in which said thermoplastic polymer is polyethylene, polypropylene, or polyamide.

Composite according to any one of Claims 1 to 3, in which each of said laminated thermoset material layers (3) comprises a stack of 5 to 30 carbon fibre fabric plies (4) prepreg by a varnish.

Composite according to Claim 4, in which said carbon fibre fabric plies (4) comprises woven yarns, and each yarn comprising at least 3000 carbon fibrils and at most 48 000 carbon fibrils.

6. Composite according to any one of claims 1 to 5, which composite undergoes a deformation known as trauma which is between 0 and 3 cm measured during a ballistic test with ammunition of the 7.62x51 NB or 7.62x39 MSC AK47 type.

7. Composite according to any one of Claims 1 to 6, which composite has a density between 0.8 g/cm³ and 1.5 g/cm³.

8. Composite according to any one of Claims 1 to 7, which composite has a flexural modulus of elasticity, in perpendicular flexion, between 20 000 MPa and 30 000 MPa, and a flexural strength of 50 to 130 MPa, measured according to the ISO 178 standard.

9. Process for manufacturing a composite (la) according to any one of Claims 1 to 8 comprising the assembling, using an adhesive, of a central thermoplastic polymer layer (2) sandwiched between two laminated thermoset material layers (3).

10. Process for manufacturing a composite (lb) according to any one of Claims 1 to 8, comprising the assembling, using an adhesive, of a thermoplastic polymer layer (2) with a laminated thermoset material layer (3); wherein the thermoplastic polymer layer (2) is a solid layer; and wherein the thermoplastic polymer layer (2) is made up of polyethylene, polypropylene, polyamide, or a mixture of at least two of these polymers.

11. Process according to Claim 9 or 10, in which the thermoplastic polymer layer (2) is obtained by stacking plies of thermoplastic polymer under a pressure between 2 MPa (20 bar) and 20 MPa (200 bar) at a temperature between 80°C and 160°C.

12. Process according to Claim 9 or 10, in which the laminated thermoset material layer (3) is obtained by stacking at least 5 carbon fibre fabric plies (4) that are prepreg with a varnish, under a pressure between 2 MPa

(20 bar) and 5 MPa (50 bar) at a temperature between 140°C and 200°C.

13. Process according to Claim 12, in which the prepreg carbon fibre fabric plies are obtained by dipping carbon fibre fabric plies in an impregnation varnish containing a resin, a hardener, a catalyst and a solvent; then evaporating said solvent.

14. Bulletproof or antishrapnel protective device comprising a composite according to one of Claims 1 to 8.

15. Use of the composite according to any one of Claims 1 to 8 as bulletproof or antishrapnel protection.