Technical Domain of the Invention

The present invention relates to Laminated glazing assembly comprising at least a front glass sheet, a second glass sheet and a glazing panel; the front glass sheet is the glass sheet facing to the bullet or blast; the second glass sheet is between the front glass sheet and the glazing panel; a first interlayer bonding the front and second glass sheets; a second interlayer bonding the second glass sheet and the glazing panel .

The first interlayer is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400 MPa and at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with

ASTM D638; G = shear storage modulus); in that the thickness of the front glass sheet is at most the thickness of the second glass sheet and in that the thickness of the front glass sheet and the second glass sheet is at most 20 mm.

The present invention relates also the use of a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400 MPa and at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus)

Background of the Invention

Nowadays, laminated glazing are mainly used within buildings elements for security application, i.e. resistance against explosion, bullet impact or defenestration.

Laminated glazing comprises glass sheets maintained by and one or more interlayers positioned between glass sheets. The interlayers employed are typically polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) for which the stiffness can be tuned. These interlayers keep the glass sheets bonded together even when broken in such a way that they prevent the glass from breaking up into large sharp pieces. For reinforcing the glazing and diminishing its global thickness, while dealing with security glazing, it’s known from US2017072662 that polycarbonate (PC) sheet and polyurethane (PU) interlayer can be used to replace interlayers between adjacent glass sheets. Moreover, for avoiding a spalling behavior of the glazing while impacted, a polyethylene terephthalate (PET) film can be used as a spallshield as described in US2009324935. However, such materials are very expensive and exhibit a bad durability in terms of both mechanics and anesthetic quality.

According to the threat, the security glazing can be designed to respond to different European standards : EN 13541 (Glass in building. Security glazing. Testing and classification of resistance against explosion pressure), EN 1063 (Glass in building. Security glazing. Testing and classification of resistance against bullet attack), EN 356 (Glass in building - Security glazing - Testing and classification of resistance against manual attack). For each standard, the level of performance declared is defined for a specific direction of impact on the security glazing. Therefore, a so-called attack face of the security glazing must be declared while selling it and the attack face is the face of the laminated glazing in front of the attack.

In the specific case of bullet resistant glazing, the design of the laminated glazing will truly depend on the targeted caliber which is shot. Indeed, the front of the laminated glazing will be required to absorb a maximum of the impact energy provoked by the bullet and the higher the caliber, the higher the impact energy on the glass. The most common method for absorbing the energy is to use thick glass plies within the front of the laminate which could go up to 12 or 15mm thick glass for the highest class described in EN 1063, i.e. BR5 to BR7. The major issues of these thick glass are their complicated maneuverability due to their weight and their deeply marked greenish color. Indeed, for the latter, the color neutrality of such thick glass is really difficult to obtain.

The weight of such laminated glazing is a problem in view of handling, manipulating, installing such glazing. The color, the transparency and the aestethism of such laminated glazing is difficult to control due to large thickness. The invention provides a solution to overcome the above described defaults.

The following description relates to an architectural glazing panel but it is understood that the invention may be applicable to others fields like transportation glazing.

Summary of the Invention

The invention relates to an improved laminated glazing assembly comprising at least a front glass sheet, a second glass sheet and a glazing panel. The front glass is the glass sheet facing to the bullet or blast, that means that the attack face is the face toward the attack of the front glass sheet of the laminated glazing assembly. The second glass sheet is between the front glass sheet and the glazing panel. A first interlayer is bonding the front and second glass sheets and a second interlayer is bonding the second glass sheets and the glazing panel.

The first interlayer is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400MPa at 30°C for a load duration of 1 sec (E = 2G(1 +v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus). The thickness of the front glass sheet is at most the thickness of the second glass sheet. The thickness of the front glass sheet and the second glass sheet is at most 20mm to reduce the thickness of the glazing panel with similar performances. According to the invention, glass sheet can be either soda lime, aluminosilicate or borosilicate. Glass sheet can be processed such as cut, grinded, strengthened, annealed, thermally or chemically tempered... At least one of the glass sheets of the glazing can incorporate solar radiation absorbents in its mass, thereby improving the performance of solar and light control. The second interlayer is a thermoplastic adhesive layer which can be any of the known sheets available for use as laminated glass interlayers can be utilized; thus, for example, plasticized polyvinyl acetal resin sheet, polyurethane resin sheet, to ethylene-vinyl acetate resin sheet, ethylene-ethyl acrylate resin sheet, and plasticized vinyl chloride resin sheet. Preferably, to simplify the assembly and the process of assembly, the second interlayer is a polyvinylbutyral based interlayer and more preferably the second interlayer is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400MPa at 30°C for a load duration of 1 sec (E = 2G(1 +v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus).

According to the invention, to reduce bullet penetration and/or to increase energy absorption, the first interlayer and/or the second interlayer can comprise several layers of the interlayer.

According to the invention, the glazing panel can be a single glass sheet, a laminated assembly or a multiple glazing assembly. In case of a glazing panel comprising a single glass sheet, any glass sheet as described above can be used and can be chosen depending of required properties in term of, for example, total thickness, coloration, penetration resistance,... In case of a glazing panel comprising a laminated assembly, any glass sheets and any interlayers as described above can be used. In case of a glazing panel comprising a multiple glazing assembly, the glazing panel comprises at least two glass sheets are separated by a spacer frame and a gap and one of these at least two glass sheet is laminated to the second glass sheet by the second interlayer. The space between the plates is closed and filled with a Gas-Gas heat exchange blocking. Usually, this Gas may be air at a pressure above ambient reduced pressure or argon or krypton. The spacer frame may be provided with a per se known manner with desiccant container, which is provided with openings to the disc space to avoid the formation of condensation moisture is effectively avoided.

According to the invention, the thickness of the front glass sheet is at most 8mm, preferably at most 5mm to control the color neutrality of the assembly. The general greenish aspect of the laminated glazing assembly will be attenuated.

It’s understood that in case of a color product for aesthetic or privacy reasons, at least one glass sheet or at least one interlayer can be body-tinted or surface treated. Different coloration can be obtained by superposing different body- tinted or surface treated glass sheets and/or interlayers. In another embodiment, the thickness of the front glass sheet is thinner than the thickness of the second glass sheet to improve the deformation resistance of the laminated glazing assembly.

In another embodiment, the front glass sheet is laminated on the surface facing to the bullet or blast with a thin glass sheet and an interlayer. This thin glass sheet can be used to keep together pieces from the front glass sheet after impact. The thickness of this thin glass sheet is preferably greater than 2 mm and more preferably between 4 mm and 5 mm. The interlayer can be any known interlayer able to maintain the thin glass sheet to the front glass sheet. The invention relates also to the use of a first interlayer in a laminated glazing assembly as described above and in examples where the first interlayer is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400MPa at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = G = shear storage modulus). The thickness of the front glass sheet is at most the thickness of the second glass sheet. The thickness of the front glass sheet and the second glass sheet is at most 20mm.

Figures

The present invention will now be more particularly described with reference to drawings and exemplary embodiments, which are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples.

Figure 1 schematically illustrates a cross-sectional view of a laminated glazing assembly according to one embodiment of the present disclosure exposed to a bullet or an explosion.

Figure 2 schematically illustrates a cross-sectional view of a laminated glazing assembly according to one embodiment of the present disclosure exposed to a bullet or an explosion. According to the invention and to the figure 1 , a laminated glazing assembly 10 comprises at least a front glass sheet 1, a second glass sheet 2 and a glazing panel 3. The front glass sheet 1 is the glass sheet facing to the bullet 6a or blast 6b, that means that the attack face 1 a is the face toward the attack of the front glass sheet 1 of the laminated glazing assembly 10. The second glass sheet 2 is between the front glass sheet 1 and the glazing panel 3. A first interlayer 4 is bonding the front and second glass sheets 1 ,2 and a second interlayer 5 is bonding the second glass sheet 2 and the glazing panel 3.

The first interlayer 4 is a polyvinylbutyral based interlayer with a Young modulus (E) between 420 and 470 MPa at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus).

According to one embodiment, the thickness of the front glass sheet 1 is 8 mm. The thickness of the second glass 2 sheet is 8 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 16 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm.

According to one embodiment, the thickness of the front glass sheet 1 is 6 mm. The thickness of the second glass 2 sheet is 8 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 14 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm.

According to one embodiment, the thickness of the front glass sheet 1 is 6 mm. The thickness of the second glass 2 sheet is 6 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 12 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm.

According to one embodiment, the thickness of the front glass sheet 1 is 6 mm. The thickness of the second glass 2 sheet is 8 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 14 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm. In this embodiment, the second interlayer 5 is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400 MPa at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus).

According to one embodiment, the thickness of the front glass sheet 1 is 5 mm. The thickness of the second glass 2 sheet is 10 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 15 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm.

According to one embodiment, the thickness of the front glass sheet 1 is 5 mm. The thickness of the second glass 2 sheet is 10 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 15 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is 0.76 mm. In this embodiment, the second interlayer 5 is a polyvinylbutyral based interlayer with a Young modulus (E) of at least 400 MPa at 30°C for a load duration of 1 sec (E = 2G(l+v); v= Poisson’s ratio of approximately 0.476 measured in accordance with ASTM D638; G = shear storage modulus). According to any embodiment, several layers of the first interlayer 4 and/or the second interlayer 5 are used to obtain the desired thickness of the interlayer. A single layer of interlayer with the required thickness can also be used.

According to any embodiment, the second layer could be a multiple layers of interlayer to decrease the penetration of the bullet into the laminated glazing assembly. For example, the second layer could be a single layer with a defined thickness or a multilayer of interlayer stacked together in order to obtain the defined thickness.

According to one embodiment, the thickness of the front glass sheet 1 is 5 mm. The thickness of the second glass 2 sheet is 10 mm. The thickness of the front glass sheet 1 and the second glass sheet 2 is then 15 mm. The thickness of the first interlayer 4 is 0.76 mm and the thickness of the second interlayer 5 is about 3 mm made of one interlayer or made of a multilayer of interlayer, for example 4 layers of an interlayer with a thickness of 0.76 mm or 8 layers of an interlayer with a thickness of 0.38 mm. Any interlayer used (4, 5) in the laminated glazing assembly 10 can be independently made of single or multiple layers of respective interlayer to obtain the desired thickness of the interlayer depending of the thickness available during the process of manufacturing such laminated glazing assembly 10. According to one embodiment, the glazing panel 3 is a laminated glazing panel comprising at least two glass sheet laminated together with an interlayer. The interlayer can be a single layer or multiple layers. This interlayer can be used to stop the penetration of the bullet and to avoid that the bullet can passed through the whole assembly, thus the thickness of this interlayer can be important depending of the desired properties of the laminated glazing assembly 10.

Any interlayer used (the first interlayer 4, the second interlayer 5 or any interlayer used inside the glazing panel 3) in the laminated glazing assembly 10 can be independently made of single or multiple layers of respective interlayer to obtain the desired thickness of the interlayer depending of the thickness available during the process of manufacturing such laminated glazing assembly 10.

In another embodiment, the glazing panel 3 is a multiple glazing panel comprising a third glass sheet laminated to the second glass sheet 2 with the second interlayer 4 and a glazing separated from the third glass sheet by a spacer and a gas layer. This kind of configuration can be used to add thermal isolation properties to the laminated glazing assembly.

According to any embodiment, the front glass sheet 1 is laminated with a thin glass sheet 11 and an interlayer 12. According to one embodiment, the thickness of the thin glass sheet 11 is about 4 mm and the thickness of the interlayer between the thin glass sheet 11 and the front glass sheet is 0.76.