Curved bullet proof glass made of glass, glass-ceramic or ceramic mechanically curved on the strike-face layer

Abstract

A curved bullet-proof composite comprising: a glass or glass-ceramic external strike-face layer having been subjected to an ion exchange process and which is mechanically curved; at least one glass or glass-ceramic intermediate layer; an internal plastic layer; and an adhesive material between the strike-face layer, the at least one intermediate layer and the internal plastic layer.

Claims

1. A process for bending a bullet-proof composite comprised of one alkali aluminosilicate or soda-lime silicate glass strike-face layer which has been subjected to an ion exchange process to obtain enough flexibility to be mechanically curved, and having a thickness less or equal to 3mm, one or more glass or glass-ceramic intermediate layers, one internal plastic layer and an adhesive material between each of the above layers, comprising the steps of: (a) individually bending by means of gravity and temperature the glass or glass-ceramic intermediate layers; and (b) mechanically bending the glass strike-face layer and the internal plastic layer by laminating by heat and pressure the glass strike-face layer, the glass or glass-ceramic intermediate layers from step (a), the adhesive materials and the internal plastic layer; wherein the softening point temperature of the glass-strike face layer is higher than the softening point temperature of the glass or glass-ceramic intermediate layers of the bullet-proof composite; wherein the lamination temperature from step (b) is less than the bending temperature from step (a); and wherein the glass strike-face layer corresponds to the convex side of the bullet-proof composite.

2. The process of claim 1, wherein the glass or glass-ceramic intermediate layers have been subjected to an ion exchange process.

3. The process of claim 1, wherein a step (c) is carried out after step (a), and consists of painting around the glass strike-face layer with black organic or inorganic paint.

4. The process of claim 3, wherein the painting with black organic paint or inorganic is done over the glass or glass-ceramic intermediate layers.

5. The process of claim 1, wherein the step (b) of heat and pressure mechanically bending is performed at a pressure ranging from 0.68 to 1.03 MPa.

6. The process of claim 1, wherein the step (b) of heat and pressure mechanically bending step is performed at a temperature ranging from 85 C. to 135 C.

Description

3. BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross section of an example of a design of a transparent glass bullet-proof composite.

(2) FIG. 2 shows a cross section of an example of a design of a transparent glass bullet-proof composite in which two layers of plastics are used in (4).

(3) FIG. 3 sketches the way a flange-containing curved bullet-proof composite can be assembled onto the door of a vehicle.

(4) FIG. 4 illustrates the way curvature radii are measured of the different material layers comprising a curved bullet-proof composite.

(5) FIG. 5 shows the lack of parallelism between material layers occupying the strike-face layer (1) and the intermediate layers (2) in a deficient bending process.

(6) FIG. 6 illustrates sodium and potassium ion exchange between glass and a salt.

(7) FIGS. 7a and 7b illustrate two embodiments of the present invention.

(8) FIG. 8 illustrates the process steps of the present invention.

4. BRIEF DESCRIPTION OF THE INVENTION

(9) Referring to embodiments shown in FIGS. 7a and 7b, the present invention discloses a curved bullet-proof composite having glass, glass-ceramic or flexible ceramic in the strike-face layer (10) in order to be mechanically curved during a low heat (temperature) and pressure lamination process. The composites can be made of one or more gravity and heat-curved glass, glass-ceramic or ceramic layers in one or more intermediate layers (20). The purpose of the adhesive materials (30) and the plastic internal layer (40) is the same as the purpose described for the adhesive materials (3) and plastic internal layer (4) in prior art.

(10) In addition, the present invention discloses a process for manufacturing the glass of the instant invention, comprising the following steps: a) (100) size (cut) glass or glass-ceramic in the strike-face layer (10) and intermediate layers (20) to the geometry or shape of the curved bullet-proof composite. Sinter the ceramic material of the strike-face layer (10) according to the shape of the curved bullet-proof composite sought to manufacture. b) (110) edge glass finishing, glass-ceramic or ceramic, i.e., strike-face layer (10) and intermediate layers (20); c) (120) individually curve by means of gravity and temperature the glass or glass-ceramic intermediate layers (20); d) (130) carryout an ion exchange process of one or several glass and/or glass-ceramics of the strike-face layer (10) and intermediate layers (20); e) (140) paint the black stripe using organic paint on the strike-face layer (10) and/or one of the intermediate layers (20); f) (150) assemble the strike-face layer (10), intermediate layers (20), adhesive materials (30) and the internal plastic layer (40); and g) (160) mechanically curve during pressure and heat lamination the strike-face layer (10), intermediate layers (20), adhesive materials (30) and the internal plastic layer (40).

5. DETAILED DESCRIPTION OF THE INVENTION

(11) Manufacturing of flat bullet-proof glass using glass-ceramic materials in the strike-face layer (1) and borosilicate, pure silica and silica glass glass in the intermediate layers (2) (FIG. 1) is already disclosed in US patent application 2010/0275767. However, prior art does not solve the problem of material bending using different softening temperatures, as far as having adequate parallelism between the strike-face layer (10) and intermediate layers (20) (FIG. 5) and avoid spacing which leads to ruptures during a heat and pressure lamination process.

(12) 5.1. Product

(13) The present invention resolves the problem of manufacturing curved bullet-proof glass when glass, glass-ceramic or sufficiently flexible ceramic is used in the strike-face layer (10) of the bullet-proof composite in order to be mechanically curved during a heat and pressure lamination process normally performed in a range between 0 and 1.52 MPa (0 and 220 psi) and a temperature range between 80 and 140 C.

(14) In addition, the present invention resolves the problem of manufacturing bullet-proof composites which incorporate glass, glass-ceramics or ceramics in the strike-face layer (10) having a softening temperature different to that of glass, glass-ceramics or ceramics used in intermediate layers (20) (FIG. 7). Given the ion exchange process of the present invention, which will be detailed below, the material selected in the strike-face layer (10) acquires the necessary flexibility for adopting the curvature given to the intermediate layers (20) by gravity and temperature without the need of using other temperature and pressure ranges during the autoclave process.

(15) Referring to FIG. 7a, the curved bullet-proof composite of the present invention may be made of an strike-face layer (10), at least one intermediate layer (20), and one internal plastic layer (40), bonded by adhesive materials (30). When referring to one element, or one layer or one material, it necessarily should be understood to include the possibility to be one or more from those elements. In a preferred embodiment of the invention, the preferred material to be used in the strike-face layer (10) is an alkali aluminosilicate with ion exchange. It should be understood that the group of alkali aluminosilicate materials comprises lithium aluminosilicate, sodium aluminosilicate or any other aluminosilicate material taken from the group of alkali materials.

(16) In the present invention, the amount of sodium oxide (Na.sub.2O) or any other oxide including sodium (Na) in its chemical formula may range between 0 and 30%. In a preferred embodiment, the chemical composite suggested for sodium aluminosilicate (SAS) may be SiO.sub.2 61%, Al.sub.2O.sub.3 16%, B.sub.2O.sub.3<1%, Na.sub.2O 13%, K.sub.2O 4%, CaO<1% and MgO 4% or any other which allows said material to acquire the necessary flexibility and mechanical resistance after the ion exchange process to be curved during the lamination process without breaking. In the preferred embodiment shown in FIG. 7a, the thickness of the strike-face layer (10) may be preferably lesser or equal to 3 mm (3 mm), the depth reached during the ion exchange process (DOL) greater or equal to 30 m (30 m) and the compression stress equal or greater than 300 MPa (300 MPa).

(17) Another preferred material for use in the strike-face layer (10) is Lithium Aluminosilicate (LAS) with ion exchange. In the present invention, the amount of lithium oxide (LiO.sub.2) or any other oxide including lithium (Li) in its chemical formula may range between 0 and 20%. In a preferred embodiment, the chemical composite suggested for lithium aluminosilicate (LAS) may be SiO.sub.2 67.2%, Al.sub.2O.sub.3 20.1%, LiO.sub.2 3.2%, MgO 1.1%, CaO 0.05%, BaO 0.9%, ZnO 1.7%, Na.sub.2O 0.4%, K.sub.2O 0.3%, TiO.sub.2 2.7% and ZrO.sub.2 1.7% or any other which allows said material to acquire the necessary flexibility and mechanical resistance after the ion exchange process to be curved during the lamination process without breaking. In the preferred embodiment shown in FIG. 7a, the thickness of the strike-face layer (10) may be preferably lesser or equal to 3 mm (3 mm), the depth reached during the ion exchange process (DOL) greater or equal to 50 m (50 m) and the compression stress equal or greater than 400 MPa (400 MPa).

(18) An important scratch resistant improvement is achieved when a chemical strengthened glass or glass-ceramic is used as strike-face layer (1) in bullet-proof composites because the compressive stresses incorporated to glass or glass-ceramics makes more difficult that scratches can be generated. Additionally, compressive stresses could avoid or retard the propagation of preexisting cracks on strike-face layer, as a result of it; the fracture of this layer could be prevented. For example, soda-lime glass could have depth of layer around 25 to 30 microns and compressive stresses between 400 and 600 MPa. So with the incorporation of new materials like alkali aluminosilicates and lithium aluminosilicates as strike-face layer in (1) in which DOL could be up to 1000 microns and compressive stresses up to 1000 MPa, the possibilities of fractures or scratches on strike-face layer are reduced.

(19) In other curved bullet-proof composites of the present invention, the use of Soda-Lime glass having ion exchange in the strike-face layer (10) is possible. In the instant invention, the minimum content of silicon oxide (SiO.sub.2) or any other oxide including silicon (Si) in its chemical formula can be 50%. In a preferred embodiment of the present invention, the chemical composite of Soda-Lime glass can be 73% SiO.sub.2, 14% Na.sub.2O, 9% CaO, 4% MgO, 0.15% Al.sub.2O.sub.3, 0.03% K.sub.2O, 0.02% TiO.sub.2 and 0.1% Fe.sub.2O.sub.3 or any other which allows said material, after being subject to ion exchange, to acquire flexibility and mechanical resistance necessary for bending during the lamination process. The thickness of the material used in the strike-face layer (10) may be lesser or equal to 3 mm (3 mm), the depth reached during the ion exchange process (DOL) greater or equal to 15 m (15 m) and the compression stress equal or greater than 200 MPa (200 MPa).

(20) In other curved bullet-proof composites of the present invention, the use of Borosilicate glass having ion exchange in the strike-face layer (10) is possible. In the instant invention, the minimum content of boron trioxide (B.sub.2O.sub.3) or any other oxide including boron (B) in its chemical formula range between 0 and 25%. In a preferred embodiment of the present invention, the chemical composite of Borosilicate glass can be 81% SiO.sub.2, 4% Na.sub.2O/K.sub.2O, 2% Al.sub.2O.sub.3, 13% B.sub.2O.sub.3, or any other which allows said material, after being subject to ion exchange, to acquire flexibility and mechanical resistance necessary for bending during the lamination process. The thickness of the material used in the strike-face layer (10) may be lesser or equal to 3 mm (3 mm), the depth reached during the ion exchange process (DOL) greater or equal to 5 m (5 m) and the compression stress equal or greater than 100 MPa (100 MPa).

(21) Alkali Aluminosilicate (SAS), Lithium Aluminosilicate (LAS), Soda-Lime and Borosilicate may be used in the strike-face layer (10) having a thickness greater than 3 mm (>3 mm). However, in these cases, the bending of said layer is not performed under pressure and heat (0 to 1.52 MPa; 80-140 C.) during lamination but instead individually by means of gravity and temperature during the bending process.

(22) The preferred materials for use in the intermediate layers are Soda-Lime glass with or without ion exchange, borosilicate glass and fused silica (SiO.sub.2 content >95%). However, the use of preferred materials of the strike-face layer (10) in the intermediate layers (20) is possible in other embodiments.

(23) Alternatively, the design of bullet-proof composites could incorporate several layers of one or different plastics as internal layers (4). FIG. 2 shows a configuration in which two layers of plastic are used. The article Ballistic Properties of Hybrid Systems for Transparent Armor Applications wrote by John W. Song et al reveals the synergistic effect of incorporate combinations of hard/soft plastics as spall shield in position (4) of FIG. 2. So that, with the incorporation of this hybrid concept a ballistic performance improvement of bullet-proof composites with same areal density is obtained.

(24) 5.2. Process

(25) As noted above, the art describes in detail the critical steps of the manufacturing process of curved bullet-proof glass using Soda-Lime or Borosilicate glass in the strike-face glass layer (1) and the intermediate layers (2) (FIG. 1), as mentioned above.

(26) Making reference to FIG. 8, the method through which the curved bullet-proof composites of the present invention are produced is described. The steps are: a) (100) size (cut) glass or glass-ceramic in the strike-face layer (10) and intermediate layers (20) to the geometry or shape of the curved bullet-proof composite. Sinter the ceramic material of the strike-face layer (10) according to the shape of the curved bullet-proof composite sought to manufacture. b) (110) edge glass finishing, glass-ceramic or ceramic, i.e., strike-face layer (10) and intermediate layers (20); c) (120) individually curve by means of gravity and temperature the glass or glass-ceramic intermediate layers (20); d) (130) carryout an ion exchange process of one or several glass and/or glass-ceramics of the strike-face layer (10) and intermediate layers (20); e) (140) paint the black stripe using organic or inorganic paint on the strike-face layer (10) and/or one of the intermediate layers (20); (f) (150) assemble the strike-face layer (10), intermediate layers (20), adhesive materials (30) and the internal plastic layer (40); and g) (160) mechanically curve during pressure and heat lamination the strike-face layer (10), intermediate layers (20), adhesive materials (30) and the internal plastic layer (40).

(27) As can be noted, the differences with prior art lie partly in the order of steps c), e) and g); i.e., they present modifications and change their order in order to make possible the production of curved bullet-proof glass which involves glass or glass-ceramics in the strike-face layer (10) different to the glass or glass-ceramics used in the intermediate layers (20). Steps c), e) and g) of the subject invention will be described in detail and the modifications contemplated in each step thereof.

(28) c) Individually curve by means of gravity and temperature the glass or glass-ceramic (120) intermediate layers (20): as mentioned in prior art, the bending of the glass and glass-ceramic layers is performed simultaneously (bending-annealing) in order to assure parallelism. The process may take anywhere between 100 and 1000 minutes because it requires a slow cooling system in order to allow for the glass/glass, glass/glass-ceramic or glass-ceramic/glass-ceramic interfaces, which cool slower than the glass/air or glass-ceramic/air interfaces, to have lesser cooling rates than the maximum temperature gradient allowed by the material in order to avoid failures due to thermal shock. Simultaneous bending of glass or glass-ceramic layers force bullet-proof manufacturers to design ballistic formulas having the same materials both in the strike-face layer (10) and the intermediate layers (20) in order to have the same softening temperature in the materials during simultaneous bending by means of gravity and temperature, thereby reducing the presence of optic defects due to excess markings during the bending process which happens when materials having different softening temperatures are simultaneously curved.

(29) The present invention resolves the problem of lack of parallelism between glass or glass-ceramic layers used in intermediate layers (20) and which must be curved by means of gravity and temperature upon performing the individual curvature of each layer in a horizontal heat tempering furnace where pieces are curved and semi-tempered or heat strengthened individually, in such a way that hot glass/glass, glass-ceramic/glass or glass-ceramic/glass-ceramic interfaces are eliminated when more than one layer is curved. The parallelism of intermediate layers (20) is assured by the use of special mold which allow for better control of the shape of the glass or glass-ceramic layers to be used in the intermediate layers (20) during the bending/semi-tempering or heat strengthened process. The above allows for the time required in the temperature and gravity bending process to be reduced in a way that curved bullet-proof glass production time is reduced and costs related with bending of intermediate layers (20) are optimized. Therefore, production capacity and energy savings increase in the production of curved bullet-proof pieces.

(30) The bending/semi-tempering or heat strengthened process performed when bending the layers of material used in intermediate layers (20) individually, allows for fragments of these curved/semi-tempered or heat strengthened materials to be of similar size to those obtained from curved-annealed materials (simultaneous bending of layers). The above is important in order not to lose resistance capacity to multiple impacts, which is very relevant when designing bullet-proof composites.

(31) e) Paint the black stripe (140) using organic or inorganic paint on the strike-face layer (10) and/or one of the intermediate layers (20): in prior art, the production of the perimeter black stripe required in bullet-proof composites having glass enamels and which generally are located on the glass used in the strike-face layer (10) reduces mechanical resistance of the glass in percentages greater than 60%. The above forces bullet-proof glass manufacturers to design the bullet-proof composites with thick glass in the strike-face layer (10). In addition, how ion exchange increases mechanical resistance of glass and glass-ceramics is known.

(32) In order to avoid the loss of mechanical resistance in glass and glass-ceramics having ion exchange used in the strike-face layer (10), it is necessary to make the perimeter black stripe with organic paint which does not reduce said mechanical properties in glass or glass-ceramics used in the strike-face layer (10). g) Pressure and heat laminate the strike-face layer (10), intermediate layers (20), adhesive materials (30) and the internal plastic layer (40) and mechanically curve by means of pressure and temperature the strike-face layer (10) of material with ion exchange and the internal plastic layer (40): The bending-annealing process of the strike-face layer (10) and of the intermediate layers (20) is generally performed simultaneously by means of gravity and temperature. However, it was explained how this simultaneous bending process requires that the materials to be used in the strike-face layer (10) and intermediate layers (20) be the same in order to avoid lack of parallelism amongst layers and avoid optic defects produced by excess markings when materials having different softening temperatures are simultaneously curved.

(33) The present invention takes advantage of the greater mechanical resistance and flexibility that the ion exchange process imparts to glass and glass-ceramics in order to incorporate them into the strike-face layer (10) of bullet-proof glass. Therefore, materials that will be used in the strike-face layer (10) may be introduced flat into the pressure and heat lamination process, which generally may range between 0 and 1.52 MPa and between 80 and 140 C. During the lamination process, the isobaric pressure inside the autoclave forces the materials of the strike-face layer (10) to take on the curvature of the previously curved and semi-tempered or heat strengthened material of the intermediate layers (20).

Example 1

(34) FIG. 7a illustrates a composite which uses Alkali Aluminosilicate (SAS), Lithium Aluminosilicate (LAS) or Soda-Lime having a thickness ranging between 2 and 3 mm with ion exchange in the strike-face layer (10) mechanically curved during the heat and pressure lamination process, a borosilicate glass layer having a thickness ranging between 9 and 13 mm in the intermediate layers (20) without ion exchange and curved/semi-tempered or heat strengthened by means of gravity and temperature, a polycarbonate layer having a thickness ranging between 1 and 3 mm in the internal plastic layer (40) and polyurethane adhesive layers (30) with a thickness ranging from 0.3 to 3.1 mm. The described composite complies with requirements set forth in NIJ 0108.01 for level III A with a thickness ranging from 14 to 17 mm; the standard formula used to comply with level III A requirements of the same norm has a thickness of 21 mm and therefore, thickness and weight reduction can range between 19 and 33%, preferably a weight reduction of 29% and a thickness reduction of 26%. In addition, the individual bending/semi-tempering or heat strengthened process of the intermediate layers (20) can be performed 10 times faster than simultaneous bending-annealing, and thus represents energy and cost savings in the production of bullet-proof glass and an increase in production of curved bullet-proof composites.

Example 2

(35) FIG. 7a illustrates a composite which uses Alkali Aluminosilicate (SAS), Lithium Aluminosilicate (LAS) or Soda-Lime having a thickness ranging between 2 and 3 mm with ion exchange in the strike-face layer (10), a Soda-Lime glass layer having a thickness ranging between 8 and 14 mm in the intermediate layers (20) with ion exchange and curved/semi-tempered or heat strengthened by means of gravity and temperature, a polycarbonate layer having a thickness ranging between 1 and 3 mm in the internal plastic layer (40) and polyurethane adhesive layers (30) with a thickness ranging from 0.3 to 3.1 mm. The described composite complies with requirements set forth in NIJ 0108.01 for level III A with a thickness ranging from 14 to 18 mm; the standard formula used to comply with level III A requirements of the same norm has a thickness of 21 mm and therefore, thickness and weight reduction can range between 0 and 30%.

Example 3

(36) FIG. 7b illustrates a composite which uses Alkali Aluminosilicate (SAS), Lithium Aluminosilicate (LAS) or Soda-Lime having a thickness ranging between 2 and 3 mm with ion exchange in the strike-face layer (10), two layers of borosilicate glass having a thickness ranging between 5 and 13 mm in the intermediate layers (20) without ion exchange and curved/semi-tempered or heat strengthened by means of gravity and temperature, a polycarbonate layer having a thickness ranging between 1 and 6 mm in the internal plastic layer (40) and polyurethane adhesive layers (30) with a thickness ranging from 0.3 to 3.1 mm. The described composite complies with requirements set forth in NIJ 0108.01 exceeding level III A and offers thickness and weight reduction ranging between 20 and 35%.

(37) The above comprises a complete and detailed disclosure of several embodiments of the inventive concept herein claimed. Any skilled person in the art shall understand that variations may exist without falling away from the scope and spirit of the invention. The inventive concept claimed herein is only defined by the scope of the following claims, which shall be interpreted according to what was disclosed in the detailed description.