Field of the Invention The invention relates to the field of bullet resistant laminated glazing. Background of the Invention

Bullet resistant glazing, BRG, provides resistance to penetration by projectiles (bullets). A laminated comprised of combinations of various types of glass and plastics are utilized to absorb and dissipate the energy of the projectile, preventing penetration and protecting the occupants of the vehicle from the projectile and any spalling of the glass. BRG commonly includes chemically tempered and heat strengthened glass layers. In a BRG laminate, the glass layers may comprise various glass compositions such as borosilicate and aluminosilicate, in addition to soda-lime, as well as glass that has been thermally or chemically strengthened. Rigid plastic non-bonding layers comprising but not limited to polyurethane, acrylic and polycarbonate are also sometimes used.

In a conventional laminated non-bullet resistant glazing, two layers of annealed soda-lime glass are bonded together by a thin sheet of thermo-plastic interlayer. This provides for improved occupant retention in the event of an accident and resistant to penetration by low energy projectiles, such as small stones, but will not stop bullets.

BRG laminates make use of combinations of various types of glass and rigid plastics to absorb and dissipate the energy of a projectile, prevent penetration and protect the occupants of the vehicle from the projectile and any spalling of the glass. The selection of materials, number of layers and thicknesses are dependent upon the level of threat that the glazing is designed to withstand. Threat levels are defined by international standards in terms of the type of projectile that the glazing must be able to stop. For a minimal small caliber projectile, a thickness of 19 mm with up to five layers of glass and plastic, not counting the bonding layers may be required. To stop large caliber military grade projectiles, the total thickness may go as high at 150 mm or even greater with multiple glass and plastic layers. The plastic bonding layer has the primary function of bonding the major faces of adjacent layers to each other. For automotive use, the most commonly used bonding layer or interlayer is polyvinyl butyl (PVB). In addition to polyvinyl butyl, ionoplast polymers, ethylene vinyl acetate (EVA), cast in place (CIP) liquid resin and thermoplastic polyurethane (TPU) can also be used. Interlayers are also available with enhanced capabilities such as solar control and sound dampening.

The types of glass that may be used include but are not limited to: the common soda-lime variety typical of automotive glazing as well as aluminosilicate, lithium aluminosilicate, borosilicate, glass ceramics, and the various other inorganic solid amorphous compositions which undergo a glass transition and are classified as glass included those that are not transparent. The glass layers may be comprised of heat absorbing glass compositions as well as infrared reflecting and other types of coatings. The rigid plastic non-bonding layers are typically comprised of but not limited to polyurethane, acrylic and polycarbonate.

The glass layers may be annealed or strengthened. There are two methods that can be used to increase the strength of glass. They are thermal strengthening, in which the hot glass is rapidly cooled (quenched) and chemical tempering which achieves the same effect through an ion exchange chemical treatment. In the chemical tempering method, ions in and near the outside surface of the glass are exchanged with ions that are larger. This places the outer layer of glass in compression. Compressive strengths of up to 1, 000 Mpa are possible. One of the major problems in the industry is the cost to produce such laminates.

Due to the low production volumes (as compared to typical non-BRG automotive laminates) and the complex multi-layer cross section and materials used, BRG glazing is labor intense to produce. Small parts are even more of a problem as the labor required to produce a small part can be just as much as required to produce a much larger part.

Another problem comes from the multiple layers. The large surface area of the edge on thick BRG laminates, with its multiple layers and interfaces between needs to be sealed to prevent damage, protect the integrity and preserve the function of the laminate. The rigid plastic and plastic bonding layers tend to absorb water which can lead to degradation of the protection level, delamination and impaired vision. Trapped water, in long term contact with the glass, will leach the sodium from the glass over resulting in a high pH which will eventually reach the point where it will attack the glass. The edge also needs to be protected from physical damage during handling, transportation and installation. Any cracks or chips in the edge will result in the laminate being rejected.

While many methods and materials have been used to seal the edge, none are optimal.

Polyurethane (TPU) film is one material that is commonly used as an edge seal. However, TPU does not a good job of blocking water. In addition, the primers and adhesives that are used to install the glass in the vehicle tend to attack TPU. These chemicals can react with the TPU and the laminate layers resulting in yellowing and delamination.

Other means that have been used include: synthetic resin such as fluoropolymer, polybutene polymer or butylpolymer, an ethylene-polymer-in-water, copolymers composed of isobutene units and at least two further polymer blocks that are composed of units derived from vinylaromatic monomers, a waterproof silicone adhesive, a hot-melt resin adhesive and an adhesive comprised of acrylate or metacrylate homopolymers or copolymers or mixtures thereof.

Many of the aforementioned require processing in an autoclave. The problem that this introduces is that if done during the initial laminating cycle, the chemicals can get in between the layers. Also, some out gassing of solvent and water will occur which may be blocked by the sealant. A second autoclave step can be added but the cost is significant.

Clearly, an improved method of fabrication that reduced the steps and labor required fabrication while improving the edge seal would be useful.

Brief Summary of the Invention A large laminate panel is fabricated and then the individual smaller laminates are cut by means of an abrasive water jet from the larger panel. After any required edge work, cleaning and priming (3M 94-3M), the laminate edge is sealed through application of a sealing film. For additional strength, adhesion promoters may also be used in addition to the primer.

The pressure sensitive sealing film (3M 441 IB) is comprised of a tough, flexible, abrasion resistant thin sheet of a water proof monomer coated with a thick layer of a soft, weather resistant, high tack, acrylic adhesive. A release layer is applied over the adhesive to aid in installation and to allow dispensing and storage on a roll. The adhesive has excellent adhesion to the glass and plastics used to make BRG laminates and to the monomer itself so that the film can be overlapped and still achieve a good seal. The film is cut to length from a roll in the case of a rectangular seal or cut from a sheet. The release backing is removed as the seal is applied. A roller, squeegee or other smoothing means is used to force out any trapped air between the glazing and the seal and to ensure good contact between the adhesive and the glazing. An overlap of about 6 mm is sufficient to bond the seal to itself. No further processing is required.

Brief Description Of Drawings Figure 1A shows the large laminated panel

Figure IB shows the large laminated panel with individual glazings cut

Figure 2 shows the individual glazings removed from trim and the remnant of large laminated panel after cutting.

Figure 3A shows the glazing with square edge prior to sealing.

Figure 3B shows the sealed glazing.

Figure 4 shows the exploded view of glazing and seal.

Figure 5 A shows the glazing with tapered edge prior to sealing.

Figure 5B shows the sealed glazing.

Figure 6A shows the glazing with tapered edge and offset outer ply prior to sealing.

Figure 6B shows the sealed glazing with tapered and offset outer ply.

Figure 7A shows the sealed square glazing and flat seal prior to application.

Figure 7B shows the sealed tapered edge glazing and flat seal prior to application.

Figure 8 shows the section AA of seal. Reference Numerals

2 Glass of rigid plastic

4 Plastic bonding interlayer

20 Laminated panel

22 Individual laminates

24 Trim

28 Outer Layer

30 Edge Seal

32 Flat seal

34 Barrier

36 High tack adhesive

38 Release backing

Detailed Description of the Invention Embodiments

1.) As shown in Figures 1, 2 and 3, a 100 mm x 200 mm x 55 mm bullet resistant glazing is comprised of 8 layers of 6 mm glass 2 with 7 layers of 1 mm thick polyurethane plastic interlayer 4 used to bond the layers together. To produce the glazings, a 1 m x 1 m large laminated panel 20 with the prescribed layers is first produced. An abrasive water jet is then used to cut the multiple glazings from the large laminated panel 20. During cutting, the large panel is placed over a water tank and supported at points that are not under the tool path of the jet so as to support the individual laminates 22 as they are cut free of the panel. The individual laminates 22 are removed from the trim 24. Each is cleaned and inspected. Any additional polishing or grinding is done. As shown Figures 7A and 8, a length of a flat sealing 32 is cut from a roll of material comprising the water/solvent barrier 34, adhesive 36 and the release backing 38. The release backing 38 on the edge seal 30 is removed as the edge seal 30 is carefully applied to the glazing. A 6 mm overlap of the edge seal 30 with itself prevents any ingress at the seam. A roller is used to press the edge seal firmly to the glazing surface. An exploded view of glazing and seal aforementioned is shown in Figure 4. As shown in Figures 1, 2, 5 and 6, a 100 mm x 200 mm x 55 mm bullet resistant glazing is comprised of 9 layers of 6 mm glass 2 with 7 layers of 1 mm thick polyurethane plastic interlayer 4 used to bond the layers together. The edges of the glazing have a taper. To produce the glazings, a 1 m x 1 m large laminated panel 20 with the prescribed layers is first produced. A 5 axis abrasive water jet is then used to cut the glazings shapes from the large laminated panel 20. During cutting, the large panel is placed over a water tank and supported at points that are not under the tool path of the jet so as to support the individual laminates 22 as they are cut free of the panel. The individual laminates 22 are removed from the trim 24. Each is cleaned and inspected. Any additional polishing or grinding is done. A 9 ^th layer of glass, which is larger and offset outboard from the edge the water jet cut portion of the laminate is required for the outermost layer 28 of the laminate. This layer is produced separately. The outer layer 28 is then bonded using an optical adhesive. As shown Figures 7B and 8, the edge seal 30 is formed by LASER cutting the flat shape from a sheet of material comprising the water/solvent barrier 34, adhesive 36 and the release backing 38. The release backing 38 on the edge seal 30 is removed as the edge seal 30 is carefully applied to the glazing. A 6 mm overlap of the edge seal 30 with itself prevents any ingress at the seam. A roller is used to press the edge seal firmly to the glazing surface. Similar to second embodiment, a spherical 100 mm x 200 mm x 55 mm bullet resistant glazing, with a radius of eight meters, is comprised of 8 layers of 6 mm glass 2 with 7 layers of 1 mm thick polyurethane plastic interlayer 4 used to bond the layers together. The edges of the glazing have a taper. To produce the glazings, a 1 m x 1 m large laminated panel 20 with the prescribed layers is first produced after the glass 2 has been thermally bent using conventional bending methods. A 5 axis abrasive water jet is then used to cut the glazings shapes from the large laminated panel 20. During cutting, the large panel is placed over a water tank and supported at points that are not under the tool path of the jet so as to support the individual laminates 22 as they are cut free of the panel. The individual laminates 22 are removed from the trim 24. Each is cleaned and inspected. Any additional polishing or grinding is done. A 9 ^th layer of glass, which is larger and offset outboard from the edge the water jet cut portion of the laminate is required for the outermost layer 28 of the laminate. This layer is produced separately. The outer layer 28 is then bonded using an optical adhesive. The edge seal 30 is formed by LASER cutting the flat shape from a sheet of material comprising the water/solvent barrier 34, adhesive 36 and the release backing 38. The release backing 38 on the edge seal is removed as the edge seal 30 is carefully applied to the glazing. A 6 mm overlap of the edge seal with itself prevents any ingress at the seam. A roller is used to press the edge seal firmly to the glazing surface.

The forms of the invention shown and described in this specification represent illustrative preferred embodiments and it is understood that various changes may be made without departing from the spirit of the invention as defined in the following claimed subject matter.