FR2597857A1 - Transparent composite material for protection against impacts and protective panel produced with the aid of such a material - Google Patents

Abstract

Transparent composite material for protection against impacts, consisting of the superposition of successive sheets and layers, characterised in that it comprises, starting at its face opposite to that receiving the impact, a first glass sheet 4 which has a high flexural strength, a laminated sheet 6 consisting of a composite of biaxially drawn thin films which are superposed and adhesively bonded to each other and at least one other complementary glass sheet 5, 9 or 10. Application to the manufacture of bulletproof or burglarproof panels.

Description

"Transparent composite material
impact protection and protection panel
produced using such a material "
The present invention relates to a structure of composite material, transparent, with a flat or possibly curved surface and capable in particular of entering into the production of a panel or of a safety glazing having a remarkable resistance vis-à-vis shocks or violent impacts that can be applied to it.

The invention also relates to the protective panel thus produced.

The invention relates more particularly, although not exclusively, to the applications of such panels made of composite material to the production of transparent glazing or screens of safety or anti-e # raction, resistant to the impact of bullets or other projectiles or again to the blast effect caused by an explosion, these panels being suitable for use in both fixed and mobile installations, in particular in building techniques or in automobile construction.

The panels or protective glazing currently known in the art generally consist of an assembly of glass plates bonded or applied to each other along their surfaces in contact by means of plastic films, in particular of polyvinyl butyral, this assembly being reinforced by a or several layers of polycarbonate, polyurethane or other similar plastic materials interposed or superimposed. These laminated structures generally provide suitable protection against the attacks specified above, in particular against the impact of a bullet or a projectile hitting the outer surface of the panel, but have at the same time inconvenience.

In particular, and as a general rule, the weight of these panels is particularly high and can reach or even exceed 100 kg per m2. Furthermore, the face-to-face assembly of a glass plate and a polycarbonate plate for example, comes up against significant implementation difficulties, due to the differences in thermal expansion between these two materials, the expansion differential between these plates being able to reach in this case 55.10 / cm / cm / C. However, daily variations in temperature of the order of 30 C on either side of an average value are not exceptional under certain conditions of use or in certain climates. This results in a dimensional difference which can, in these circumstances, reach in addition or in minus 1.65 mm linear meter of glazing, which is considerable and obviously poses major problems in as regards the composition of the adhesives which, at the interface, bind any two elements in the structure.

To withstand these stresses, the adhesives contain components, in particular plasticizers, which may separate later, after setting.

In the case of polycarbonate, it has been observed that preferential migrations of some of these components induce cracking and significantly lower the mechanical characteristics of the material, this phenomenon being able to occur during the manufacture of the product.

The present invention relates to a transparent composite material, the structure of which is designed in such a way that it avoids the drawbacks of the prior solutions, in particular vis-à-vis the effects of variations in the surrounding temperature, due in particular to the fact that 'it eliminates the use of one or more layers of polycarbonate in contact with a glass plate, this composite material having by itself a very greatly improved impact resistance, combined with a substantially reduced weight for comparable performance.

The invention also relates to a protection and safety panel using this composite material by combining it with an energy-absorbing device capable of absorbing in combination with the behavior of the material itself, the effects of impact of a projectile or more generally of an impact on the exposed face of this panel.

To this end, the transparent composite impact protection material, formed by the superposition of successive plates and layers, is characterized in that it comprises, from its face opposite to that receiving the impact, a first glass plate having high flexural strength, a laminated layer consisting of a complex of two-stretched, superimposed and mutually bonded thin films and at least one other complementary glass plate.

Preferably, the complementary glass plate is a plate having high flexural strength, similar to the first plate and is in turn covered by at least one plate of another glass having good compressive strength.

As a variant, the complementary glass plate is a plate having good compressive strength, directly applied to the complex of biaxially stretched films constituting the laminated layer.

The bond between each plate and layer is made with any adhesive of suitable characteristics.

In particular, this bond can be provided by an intermediate film of organic nature, of a type known per se, for example made of polyvinyl butyral. Advantageously, the thickness of the binding film is chosen to be between 0.3 and 3 mm; where appropriate, it can be combined with a thin transparent polyester film.

According to one particular characteristic, the laminated layer of the complex is formed by the superposition of 2 to 20 bi-stretched elementary films, each having a thickness of between 100 and 300 microns and preferably between 175 and 250 microns.

The bi-stretched films of the laminated layer are produced by means of plastic materials, in particular and depending on the applications of the material, in polyethylene glycol terephthalate, polyamides or even in the form of thin films of other polyester materials, suitable for undergoing , during manufacture, a drawing operation in two perpendicular directions.

Experience shows in particular that the biaxially stretched films having undergone a similar treatment, at appropriate temperatures, have very greatly improved mechanical characteristics, more than two to three times greater than those of the material which constitutes them unstretched. These films also comprise, due to the treatment thus carried out, an amorphous state, giving them the transparency necessary in the context of the application more especially envisaged according to the invention. In addition, they have the essential advantage of having a low coefficient of linear expansion, at most and equal to 20 x 10 6 / cm / cm / C. Under these conditions, the differential expansion between the laminated layer of bi-stretched films and the high flexural strength glass plate (s) applied to the latter is no more than 8 to 10 x 10 o / cm / cm / 'C, that is to say a value at least five times lower than that observed with the prior structures known in the art, in particular using glass-polycarbonate complexes, and even eight times lower than that which occurs with other structures involving transparent plastic materials of the kind for example acrylic resins.

The complex of bi-stretched thin plastic films constituting the laminated layer arranged between the two glass plates also makes it possible to reduce the thickness of this layer and in particular that of the adhesive providing the bond between two successive films in the layer, to only a fraction of a micron, thus ensuring good transparency of the layer, the compressive strength of which can, on the other hand, be very high. On the other hand, as a result of a significant bending in particular following the impact of a bullet or a similar shock, a delamination effect of the successive films may occur in the layer, contributing to significantly increase the capacity. resistance of the material vis-à-vis shocks thanks to a better absorption of the energy of the projectile by the work necessary to obtain this delamination.

In a preferred embodiment of the composite material according to the invention, the laminated layer is placed between two chemically toughened glass plates, exhibiting high flexural and tensile strength. By way of example, one can advantageously use a tempered glass of the type marketed under the reference "VHR" by the company GLAVERBEL. These plates have a thickness equal to or different from one to the other, between 1, 5 and 5 mm and preferably between 1.5 and 3 mm. The glass plate (s) with good compressive strength applied against the external face of one of the glass plates with high flexural strength or, where appropriate, directly against the laminated layer, are preferably in number between 2 and 5. and have varying thicknesses from one to the other, generally between 3 and 15 mm and preferably between 4 and 10 mm, the thickest plate being placed opposite the first high strength glass plate bending.

Advantageously, the glass plate (s) with good compressive strength are made of silicate, annealed glass of the type known in the art by implementing the so-called "Float Class" process.

The invention also relates to a panel for protection in particular against impacts produced according to the invention using the transparent composite material, the characteristics of which are specified above, this panel having an outer front face and a rear face. interior, characterized in that the rear face is formed by the first glass plate with high flexural strength and the front face by the complementary glass plate, the thickness of the various plates and layers of the panel being determined in such a way that under the effect of an impact exerted on its front face, the deformation of the panel is established so that the glass plate with high bending strength against which is placed the laminated layer constituting the complex of bi films -drawn is placed with this layer beyond the plane of the neutral fiber of the panel.

Also according to the invention, the protective panel is associated with a damping device, consisting of an outer frame, in particular metal with a generally U-shaped section for the engagement of the side edge of the panel and of a block made of elastomer mounted in the frame and resting against a branch of the U on the one hand and against a face facing the side edge of the panel penetrating inside the frame on the other hand.

According to an additional feature, the side edge of the panel is lined with a metal rebate suitable for being placed between the elastomer block and the opposite branch of the U.

According to another particular characteristic, a flat enveloping sealing gasket is mounted between the lateral edge of the panel and the metal lining rebate.

Advantageously, a guide forming a spacer wedge is placed between the bottom of the U of the outer frame and the lining rebate in order to immobilize the panel transversely in this frame.

The nature, shape and mechanical characteristics of the block of elastomeric material are chosen on demand, in order to obtain an optimal damping effect of the panel following the impact created by a projectile or other shock, hitting the front face of this. Thus, the elastomeric block may have a square or rectangular section and may be produced in a single part or, as a variant, in several superimposed flat elements, comprising crushing hardnesses which may or may not vary from one element to another.
This block can also and depending on the case be made of a solid material or a material with a cellular structure, natural or synthetic.

Advantageously and also according to another characteristic, the U-shaped outer frame is provided with a flat gasket forming a retaining element and stopper for the trim rebate of the panel in order to immobilize the latter longitudinally resting against the available guide. s ~ é against the bottom of the frame.

Whatever the embodiment envisaged, it goes without saying that the panel according to the invention can use a composite material comprising, with the envisaged structure, a variable number of glass plates, the nature of which can also vary in the same way. than the thickness of these plates or that of the laminated notch of bi-stretched plastic films.

In all cases, during an impact on the front face of the panel, this and the plates which compose it work in compression while, placed on the other side of the neutral fiber of the assembly, the rear face works only in traction, the bending forces transmitted by this face being absorbed by the damping device constituted by the outer support frame and the elastomer block that it comprises.

Advantageously, the annealed silicate glass constituting the front face of the panel will be chosen so that the latter has a compressive strength of at least of the order of 100 daN / mm2, together with a tensile strength of the panel. order of 4 to 5 daN / mm2. On the other hand, the assembly formed by the laminated layer of thin bi-stretched films and the glass plate (s) with high flexural strength, placed towards the rear face of the panel located on the other side of the plane of the neutral fiber of the latter will be determined so as to have a flexural strength of the order of 30 to 40 daN / mm2. In addition, the laminated layer itself will usually have a tensile strength of the order of 20 to 40 daN / mm2, the elongation of this laminated layer at break being greater than 100%.

The invention thus makes it possible to produce a panel with a composite structure, the design of which provides, by making optimum use of the characteristics of the various elements which constitute it, a particularly high mechanical resistance, in particular with regard to the impacts of projectiles or the effects of various shocks exerted on the front face of this panel. At the same time, the use of successive plates and layers, the characteristics of which correspond respectively to distinct but complementary objectives, makes it possible to reduce their relative thicknesses to what is strictly necessary and consequently to obtain a much lower panel weight, for equal performance, to those of the solutions heretofore known in the art.

Another advantage of the composite material according to the invention and consequently of the protective panel produced using the latter, results from the use of a complex of films with high mechanical resistance, attached to at least one sheet of glass having a high resistance to impact and bending, the latter constituting the rear face, opposite to the front face receiving the impact. Indeed, such a plate can not only withstand relatively large bends without damage, but also, due to the structure obtained by chemical dipping, provides a satisfactory solution to the problem of scratch resistance that arises with plastic materials generally. used on the rear face of conventional composite panels.With the material of the invention, cleaning the rear face of the panel does not pose any difficulty, the adhesion of dirt on this face by electrostatic effect being moreover limited to a very low level . Finally, the use of a glass with high mechanical resistance to constitute the rear face makes it possible to give this panel a high fire resistance, greater by at least an order of magnitude with respect to that of composite materials using a layer of apparent plastic, as used frequently in currently known structures.

The damping device ensuring the support of the panel by its outer frame also provides particular advantages, reinforcing the advantage of the composite material used, in the event of impact of a projectile on the front face of the panel. Thus, the block of elastomer against which the side trim rebate of the panel rests is preferably made of an elastic material, such as synthetic or natural rubber, the hardness of which can be chosen from a wide range of values and is at less of the order of 45 Shore.

The shape of the elastomer block can be any; advantageously, it is determined according to the nature and the configuration of both the panel and the frame supporting the latter, so as to present a sufficient bearing surface for the lining rebate. However, the dimensional characteristics of the elastomer block mounted in the outer frame are chosen with tolerances wide enough to take into account a possible unequal distribution of the forces on the front face, in particular in the case where the impact on the panel does not occur. produced not in the vicinity of the center of it but in a lateral region. Whatever the location of the impact, the elastomer block will thus ensure adequate damping of the panel in bending, while limiting any deterioration of the latter.

Other characteristics of a composite material and of a protective panel associated with a damping device according to the invention will become apparent from the following description of an exemplary embodiment, given by way of indication and without limitation, in reference to the accompanying drawing in which the single figure is a view in cross section and in partial perspective of a part of the transparent composite panel in question.

The composite protective panel shown in this figure consists essentially of a stack of plates 1, constituting a laminated structure having a rear face 2 and a front face 3, the rear face 2 being by convention directed towards the inside of a room or other enclosure while the front face 3 is disposed outwardly thereof.

On the side of its rear face 2, the composite panel 1 comprises, in the example considered, two parallel plates 4 and 5, made of a glass with high mechanical resistance, in particular to bending, in particular of a chemically toughened glass. such as that known under the trade reference VHR, manufactured by the company CLAVERBEL. These plates 4 and 5 can have the same thickness or different thicknesses, in all cases between 1.5 and 5 mm. In general, however, the plate 5 located closest to the front face 3 of the panel 1 has a thickness greater than that of the plate 4 located closest to its rear face 2. In the example shown in the figure, the plate 4 thus has a thickness of between 1.5 and 2.5 mm, while plate 4 for its part has a thickness of about 3 mm.

In accordance with the invention, there is placed between the glass plates 4 and 5, a layer 6 of a laminated complex, consisting of the superposition of bi-stretched plastic films, assembled together in successive stacks, each of these films having a thickness between 100 and 300 microns and on average a thickness of about 200 microns. These films are made of a plastic material, preferably chosen from polyethylene glycol terephthalate (PET), polyamides such as those sold by the company DYNAMIT NOBEL under the trade name of Trogamid T or even other materials, in particular polyesters. These bi-stretched thin films in the laminated layer 6 are glued from one to the other with extremely low adhesive thicknesses, preferably of the order of a fraction of a micron, making it possible in particular to ensure the 'together a high transparency coefficient at the same time as a high compressive strength. In addition, between the glass plates 4 and 5 on the one hand and the intermediate layer 6 of thin films on the other hand, are arranged during the manufacture of the panel, bonding films such as 7 and 8, preferably consisting of made of a plastic material of the type of polyvinyl butyral, by combining this binding film, if necessary, with a complementary polyester film, the total thickness possibly varying between 0.3 and 3 mm.

On the assembly constituted by the plates 5 and 6 and the laminated layer 6 arranged between them are then applied towards the front face 3, two other plates, respectively 9 and 10, of a glass of a different nature from that which constitutes the plates 4 and 5, these plates 9 and 10 preferably being produced by means of an annealed silicate glass, produced according to the conventional process called "Float-Glass". As for the plates 4 and 5, the silicate glass plates 9 and 10 may have identical but preferably different thicknesses, the plate 10 located closest to the front face 3 having a thickness greater than that of the plate 9. In the example considered, the plate 9 thus has a thickness of the order of 4 mm while the plate 10 has for its part a thickness of approximately 6 mm. In addition and as previously, the connection between the plate 5 and the plate 9 on the one hand, between this plate 9 and the plate 10 on the other hand, is each time produced by means of plastic bonding films, again in polyvinyl butyral, respectively 11 and 12, these films being in all points similar to films 7 and 8 previously mentioned.

The composite panel 1 thus produced has a total thickness of about 18 to 20 mm, these dimensions however not being critical and being able to vary, in particular according to the number of high resistance glass plates on the one hand, of silicate glass. on the other hand entering into its composition.

In all cases, however, according to the invention, the panel t is associated with a damping device, allowing it to withstand without damage the effects of significant shocks occurring on the outside against its front face 3, in particular allowing to transmit to this device the efforts created by the impact thus collected.

This damping device, shown in partial section and generally designated under the reference 13, comprises firstly a metal rebate 14 whose lateral sides 15 and 16 and the lateral connecting part 17, cover the edge of the panel 1, with interposition between that here and the rebate of a flat gasket 18, made of a suitable elastomeric material.

The panel 1 thus provided with its metal rebate 14 is mounted inside an outer frame 19, comprising two flat edges 20 and 21 and a side wall 22. Between the latter and the rim 20 arranged under the rebate 14 on the rear face of the panel is arranged a block 23 of a suitable material, in particular synthetic or natural rubber, compact or with a cellular structure. This block 23 can be made in one piece or, as illustrated in the example shown, consist of three superimposed elements, respectively 23a, 23b and 23c, these having in this example different thicknesses but possibly in other variants have the same thickness and / or be made of different materials from one element to another.

The equipment of the panel 1 is completed during assembly thereof inside the frame 19 by placing between the upper part 15 of the rebate 14 and the parallel edge 21 of the frame 19, a seal 24, forming retainer and stop member for immobilizing the assembly, the rebate 14 also resting against wedges or lateral ribs 25 provided between the side 22 and the central part 17 of the rebate. Finally, the immobilization of the block 23 in the frame 19 can be reinforced by means of a return 26, provided at the end of the lower rim 20 so as to partially cover the block 23.

A composite panel is thus produced, in particular for anti-bullet or anti-intrusion use, exhibiting remarkable resistance to shocks or impacts, in particular from projectiles or bullets striking its front face, in which the recommended structure makes it possible to '' absorb the energy of the impact under the best conditions by transmitting it to the damper assembly supporting the panel, the front face receiving the impact working essentially in compression while the rear face undergoes tensile forces. are in these conditions perfectly adapted by their nature and their thickness to these particular efforts, the glass plates with high flexural strength with their intermediate layer of bi-stretched films being arranged towards the rear face of the panel beyond the fiber neutral of the structure, the bending forces of the panel, due to the impact, can also be at least partly eliminated by any delamination thin films in the intermediate layer constituting the complex.

Of course, it goes without saying that the invention is not limited to the exemplary embodiment described above which has been given only by way of example, the composite panel possibly consisting in particular of a number of superimposed glass plates different from that envisaged in this example. In addition, this panel can have both a flat profile and a curved profile, produced using conventional techniques for bending glass plates.

However, in addition to the distribution of the plates in the manner indicated with respect to the neutral fiber of the panel, care should be taken to preferably constitute the rear face by a high resistance glass plate, presenting with regard to fire and scratches , the advantages already mentioned. In all cases, however, with equal dimensions and impact resistance characteristics, the panel obtained will have a weight much less than that of the solutions known in the art, requiring the association of materials of the polycarbonate type with glass plates, resulting in structures generally heavy and above all too sensitive to variations in ambient temperature.

Claims (26)

1. Transparent composite material for impact protection, consisting of the superposition of successive plates and layers, characterized in that it comprises, from its face opposite to that receiving the impact, a first glass plate (4) having a high flexural strength, a laminated layer (6) consisting of a complex of two-stretched, superimposed and mutually bonded thin films and at least one other complementary glass plate (5, 9 or 10). 2. Transparent composite material according to claim 1, characterized in that the complementary glass plate (5) is a plate having a high flexural strength, similar to the first plate (4) and is in turn covered by at least a plate (9, 10) of another glass having good compressive strength. 3. Transparent composite material according to claim 1, characterized in that the complementary glass plate (9,10) is a plate having good compressive strength, directly applied to the complex of bi-stretched films constituting the laminated layer. 4. Transparent composite material according to one of claims 1 to 3, characterized in that the interface between each glass plate (4, 5) with high flexural strength and the laminated layer (6) is produced by means of 'an adhesive bonding intermediate film (7, 8) of plastic material. 5. Transparent composite material according to claim 4, characterized in that the binding film (7, 8) consists of polyvinyl butyral. 6. Transparent composite material according to any one of claims 4 or 5, characterized in that the bonding film (7, 8) has a thickness between 0.3 and 3 mm. 7. Transparent composite material according to any one of claims 4 to 6, characterized in that the bonding film is associated with a transparent thin film of polyester. 8. Transparent composite material according to any one of claims 1 to 7, characterized in that the laminated layer (6) consists of the superposition of 2 to 20 bi-stretched elementary films, each having a thickness between 100 and 300 microns. 9. Transparent composite material according to claim 8, characterized in that the bi-stretched films of the laminated layer are produced by means of plastic materials. 10. Transparent composite material according to claim 9, characterized in that the plastic material of the bi-stretched film is chosen from polyethylene glycol terephthalate, polyamides or other polyester materials capable of undergoing a stretching treatment. 11. Transparent composite material according to any one of claims 1 to 10, characterized in that the high tensile strength glass plates (4, 5) are made of chemically toughened glass. 12. Transparent composite material according to claim 11, characterized in that the glass plate or plates with high flexural strength have a thickness between 1.5 and 5 mm and preferably between 1.5 and 3 mm. 13. Transparent composite material according to any one of claims 1 to 10, characterized in that the glass plate or plates with good compressive strength (9, 10) are made of silicate glass, annealed. 14. Transparent composite material according to claim 13, characterized in that the glass plates with good compressive strength have a thickness between 3 and 15 mm, preferably between 4 and 10 mm. 15. Transparent composite material according to any one of claims 1 to 14, characterized in that a bonding film (11) is also provided at the interface between the glass plates with high flexural strength and the plates. good resistance to compression. 16. Transparent composite material according to claim 15, characterized in that the bonding film (11) is of the same nature as the bonding film between the high tensile strength glass plates (4, 5) and the laminated layer. (6) of bi-stretched films. 17. Anti-bullet or burglary protection panel produced by means of a composite material according to any one of claims 1 to 14, having an outer front face (3) and an inner rear face (2), characterized in that the rear face is formed by the first glass plate with high bending strength (4) and the front face by a complementary glass plate (5, 9 or 10), the thickness of the various plates and layers of the panel being determined such that under the effect of a shock exerted on its front face, the deformation of the panel is established so that the glass plate with high bending resistance against which is placed the laminated layer constituting the complex of bi-stretched films (6) is arranged with this layer beyond the plane of the neutral fiber of the panel. 18. Protective panel according to claim 17, characterized in that it comprises a damping device (13) consisting of an outer frame (14), in particular of metal with a generally U-shaped section for engagement of the side edge of the panel. and a block (23) of an elastomeric material mounted in the frame and resting against a branch (20) of the U on the one hand and against the rear face (2) facing the lateral edge of the panel penetrating into the inside the frame on the other hand. 19. Protective panel according to claim 18, characterized in that the lateral edge of the panel is lined with a metal rebate (14) suitable for being disposed between the elastomer block (23) and the opposite branch (21) of the U. . 20. Protective panel according to claim 19, characterized in that a flat enveloping sealing gasket (18) is mounted between the lateral edge of the panel and the metal lining rebate (14). 21. Protective panel according to any one of claims 19 or 20, characterized in that a guide (25) forming a spacer is arranged between the bottom of the U of the outer frame (19) and the lining rebate ( 14) in order to immobilize the panel transversely in this frame. 22. Protective panel according to any one of claims 18 to 21 characterized in that the elastomer block (23) has a square or rectangular section. 23. Protective panel according to any one of claims 18 to 22, characterized in that the elastomer block (23) is made of a synthetic or natural, compact or cellular material. 24. Protective panel according to any one of claims 18 to 23, characterized in that the elastomer block (23) consists of several elements (23a, b, c) superimposed, of identical or different crushing hardnesses. from one element to another. 25. Protective panel according to any one of claims 21 to 24, characterized in that the outer frame (19) with a U-section is provided with a sealing gasket forming a retaining and stop element (24). for the lining rebate (14) of the panel in order to immobilize the latter longitudinally in abutment against the guide (25) placed against the bottom of the frame. 26. Protective panel according to any one of claims 17 to 25, characterized in that it comprises at least two glass plates (4, 5) with high tensile strength enclosing a laminated layer (6) of bi films. -drawn and at least two glass plates (9, 10) with good compressive strength, the panel having a thickness between 18 and 20 mm.