FR2876786A1 - Laminated structure resistant to perforating projectiles, e.g. bullet proof glass, has at least one layer at up to 160 degrees to front surface - Google Patents

Abstract

The laminated structure, especially transparent and resistant to bullets, splinters or similar, has a first glass surface designed to receive the impacts and a second, opposite surface with a projectile absorbing and/or stopping function, linked to one another by intermediate adhesive layers. At least one glass layer has its face directed towards the first surface set at an angle of up to 160 degrees to the main plane of the structure. The surface of the structure designed to receive the initial impacts is reinforced.

Description

LAMINATED STRUCTURE RESISTANT TO

PERFORATING PROJECTILES

  The present invention relates to transparent walls with high ballistic resistance.

  For ballistic resistance is meant more particularly in the sense of the invention the resistance of the wall to at least one shot under conditions similar to those of level BR 7 of the standard FR EN 1063 except that it defines three shots at the vertices of an equilateral triangle of 120 mm side. These conditions are extremely demanding and involve a 7.62 x 51 perforating projectile fired at 10 m; an example of such a piercing projectile is a bullet with a steel core, a brass envelope ending in a lead base. The piercing projectile is fired at variable speeds. The ballistic resistance is evaluated by the fact that the wall is not traversed by the balls, that is to say that the safety of a person located on the side of the wall opposite the impacts, is ensured.

  Applications particularly concerned are armored automobile windows, bank counters, security booths, showcases for high value products, etc.

  The protection vis-à-vis the piercing projectiles may require relatively large wall thicknesses, which may reduce their transparency and optical quality if necessary. It is therefore important to provide the required ballistic protection by decreasing the thickness of the wall; weight reduction is another benefit.

  To this end, the subject of the invention is a particularly transparent, ballistic-resistant laminated structure, comprising a first face intended to receive one or more impacts of projectiles, such as bullets, splinters or the like, and a second opposing face with a function of damping and / or stopping of said projectiles, said laminated structure being moreover constituted of several sheets of glass connected to each other by means of intermediate adhesive layers.

  This laminated structure is distinguished by the fact that at least one of said glass sheets has at least its face oriented towards said first face of the laminated structure, forming, with respect to the main plane of the structure, an angle at most equal to 160 , preferably at 150.

  Thus, the projectile meets this relatively hard surface forming a large angle, and is deflected towards the periphery of the wall, out of reach of people to protect.

  The glass sheet having the characteristic angle of the invention may be the one that the projectile meets the first, or another. In all cases, the optical quality is obtained only if the surface irregularities such as bumps, hollows, inclinations forming the aforementioned angle, are compensated by creep of adhesive material. In particular, when these surface irregularities belong to the glass sheet receiving the projectile first, it is important to cover this glass sheet with transparent thermoplastic adhesive, for example, at a sufficient temperature and under the conditions of application allowing both filling, perfect plugging of the irregularities, and obtaining the two main surfaces of the laminated structure to perfect flatness, parallelism or curvatures (diopter), insofar as the refractive index of the filling material is similar of the glass index.

  For the purposes of the invention, the term "glass sheet" means any sheet of glass-silosodocalcic, borosilicate ... and, by extension, vitroceramic, ceramic, in particular optical, such as polycrystalline aluminum oxynitride composition.

  Said second opposite face with damping and / or stopping functionality of said projectiles consists of a polycarbonate sheet or the like connected to the rest of the structure by an interlayer adhesive layer such as polyurethane or, preferably, a poly film (Ethylene terephthalate) coated with an anti-scratch siloxane varnish, and connected to a glass sheet of the laminated structure via an adhesive layer of PVB.

  According to one embodiment, said face facing said first face of the laminated structure is made of printed glass, that is to say obtained by pressing the glass sheet at a thermoplastic deformation temperature.

  In other embodiments, a subtractive method is employed: the glass surface is etched, for example by hydrofluoric acid, in the presence of a mask.

  In yet another way, a contribution of material is made by sol-gel molding; it may be silica obtained from a precursor such as an alkoxide (tetraethoxysilane ...) in aqueous solution and / or organic, optionally with heat treatment.

  Preferably, said face facing said first face of the laminated structure has relief patterns delimiting, relative to the main plane of the structure, the required angle.

  Patterns that are perfectly suitable for carrying out the invention are pyramids with heights of between 0.2 and 5 mm, and defining, with respect to the main plane of the structure, angles of between 160 and 110.

  On the other hand, the glass surface intended to receive the first or bullet impacts, is advantageously enhanced. This measure indeed improves protection against piercing projectiles.

  The reinforcement is carried out in accordance with two main variants: The glass surface intended to receive the first or the bale shots, is chemically quenched, as described, for example, in patent FR 2 595 091, the chemical quenching consisting in replacing ions of the surface of a silico-soda-lime glass sheet, for example, by others of larger diameters, so as to create a compression; The glass surface intended to receive the first or the bale shots is coated with a layer of mechanical reinforcement. It is in particular Si3N4, hydrogenated tetrahedral amorphous carbon C: H (called DLC for Diamond Like Carbon) ... The thickness of these layers is in particular between 5 and 500 nm, and does not exceed, by order decreasing preferably, 300 nm, 100 nm, 50 nm, 25 nm. It is typically 10 nm.

  Si3N4 is obtained by magnetic field assisted sputtering (magnetron) using a metal-doped silicon target such as Al to make it sufficiently conductive, and in a nitriding atmosphere. 25 30

  The DLC layers can result from the dissociation of a precursor such as CH4, C2H6, C2H4, C2H2 ... in an ion source (based or not on the principle of anode anode layer source layer with or without ion acceleration grid , excited by direct current, alternating or microwave radiation), the ion flow thus created being directed on the heated substrate or not with energies between 100-2000 eV. The DLC layers may also be obtained by any other method such as chemical vapor deposition (CV ()).

  A significant favorable effect is obtained, on the other hand, in single or multi-impact impact, in that at least one of the interlayer adhesive layers of the laminated structure separating two sheets of glass or a sheet of glass and a sheet of plastic material such as polycarbonate, have a Young's modulus at 25 C at least equal to 100 MPa, preferably 400 MPa, and particularly preferably 700 MPa. Examples are a polyvinylbutyral with a low plasticizer content (in particular consisting of 100 parts of resin and 19 parts of n-hexyl adipate), a high modulus thermoplastic polyurethane ...

  Advantageously, the total thickness of the laminated structure is between 25 and 55 mm, preferably between 30 and 50 mm.

  Other objects of the invention consist of a glazing resistant to one or more impacts of bales, consisting of a laminated structure as described above, it being specified that said first face is oriented on the side from which the impact originates. , in particular such a glazing resistant to ammunition tungsten carbide WC and hard balls with hard or hardened steel cores covered with brass envelopes ending in a lead or incendiary base, in particular of 7.62 x calibres 51, and usual speeds for a shot at 10 m; É A land, water or air transport vehicle, a building, an airlock, a window, a ticket office, a booth (telephone, elevator, etc.), an interior wall or a door comprising such a glazing unit.

  The invention is now illustrated in the following embodiments. 30

Example 1

  Two laminated structures are subjected to ballistic resistance tests. The components of the structures are sheets designated by the following abbreviations, associated with their thicknesses (in mm): RT = sheet of annealed float soda-lime glass; PVB = standard polyvinylbutyral; PU = polyurethane; - PC = polycarbonate.

  First laminated structure: 4 RT / 0.76 PVB / 19 RT / 0.76 PVB / 10RT / 0.76 PVB / 2RT / 1.2 PU / 3 PC Second laminated structure: Only varies from the first one by replacing 4 RT by a sheet of 4 mm of printed glass, pyramids of 1 mm high and sides to 45 (forming with respect to the main plane of the laminated structure, an angle of 135). Each pyramid is joined to its base with four others.

  The total thickness of the two structures is 41.53 mm.

  The test consisted of pulling at variable speeds in the center of a 300 mm x 300 mm test piece, a perforating steel core bullet, brass casing ending in a 7.62 x 51 lead base.

  A limit velocity of perforation (VLP) is calculated as the average between the highest unthreaded velocity and the lowest traversal.

  The VLPs are for the first and second structures 737, respectively 758 m / s.

  These values reflect the superiority of the structure in which the printed glass sheet replaces a single sheet of glass of the same thickness.

Example 2

  The following structures are evaluated: Third structure RT / (0.76 PVB / 10 RT) x 3 / 1.25 PU / 4 PC Fourth structure Negative of the third only by contribution, on the face receiving the impact, of a layer of hydrogenated tetrahedral amorphous carbon (DLC) defined above, and a thickness of 10 nm. The total thicknesses of the third and fourth structures are substantially identical, with a value of 47.53 mm.

  The same test is carried out as in Example 1.

  The VLPs are, for the third and fourth structures, 865, respectively 885 m / s.

  Therefore, the contribution of the DLC layer as the first layer struck by the projectile, substantially increases the resistance to piercing bullets.

  Larger laminated layer thicknesses than those of these examples may be chosen where multi-impact strength is required.

Claims (1)

7 CLAIMS   1. A particularly transparent, ballistic resistance laminated structure, comprising a first face intended to receive one or more impacts of projectiles, such as bullets, splinters or the like, and a second opposite face with a damping and / or stopping function of said projectiles, said laminated structure being moreover composed of several sheets of glass connected to each other by means of intermediate adhesive layers, characterized in that at least one of said glass sheets has at least one face facing said first face of the laminated structure, forming, with respect to the main plane of the structure, an angle at most equal to 160 2. laminated structure according to claim 1, characterized in that said angle is at most equal to 150.   3. laminated structure according to one of the preceding claims, characterized in that said face facing said first face of the laminated structure is made of printed glass.   4. A laminated structure according to one of the preceding claims, characterized in that said face facing said first face of the laminated structure has relief patterns delimiting, relative to the main plane of the structure, the required angle.   5. A laminated structure according to claim 4, characterized in that said patterns are pyramids of heights between 0.2 and 5 mm, and delimiting, with respect to the main plane of the structure, angles between 160 and 110.   6. Laminated structure according to one of the preceding claims, characterized in that the glass surface for receiving the first or bullet impacts, is reinforced.   7. A laminated structure according to claim 6, characterized in that the glass surface intended to receive the first or bullet impacts, is chemically quenched.   8. laminated structure according to claim 6, characterized in that the glass surface intended to receive the first or bullet impacts, is coated with a mechanical reinforcing layer.   9. A laminated structure according to one of the preceding claims, characterized in that at least one of the intermediate adhesive layers that it comprises, and which separate two sheets of glass or a glass sheet and a plastic sheet such as polycarbonate, have a Young's modulus at 25 C at least equal to 100 MPa, preferably at 400 MPa, and particularly preferably at 700 MPa.   10. A glazing resistant to one or more bullet impacts, consisting of a laminated structure according to one of the preceding claims, said first face being oriented on the side from which the impact is expected.   11. Transport vehicle land, water or air, building, airlock, showcase, window, cabin or inner wall, door comprising a glazing unit according to claim 10.