FIELD OF THE INVENTION

The present invention is in the field of protective and ballistic proof materials, more specifically, compound protective or armored transparent structures.

BACKGROUND OF THE INVENTION

An armored/ballistic glass pane may consist of a single armored layer or a combination of several glass layers interleaved with bullet proof layers, for example plastic layers. Examples of protective or armored glass are disclosed in US Patent Application 2004/0209053.

A common issue with such armored glass is delamination between the glass and plastic layers that are typically used. Delamination results in decreased protection from bullets or other ballistic threats. In such case, the armored glass may need to be replaced. An average life of ballistic glass that comprises a combination of a glass layer attached to a polycarbonate layer is about two years. The solution as provided in the instant invention can considerably prolong the life of the armored glass. SUMMARY OF THE INVENTION

In accordance with embodiments of one aspect of the present invention, there is provided a transparent armored composite structure comprising: an external layer comprising at least one glass and/or transparent plastic layer arranged to face toward an expected impact; a rear layer comprising a plastic layer; and a spacing mechanism intermediate the external layer and the rear layer defining a space therebetween, wherein rear layer comprises a moisture proof coating.

The term "moisture proof material" as used herein the specification and claims denotes any material that hinders the passage of moisture. The moisture proof material is primarily intended to reduce the passage of moisture into the space provided by the spacing material ; however, in cases where the rear layer further comprises a glass layer adjacent its plastic layer, the moisture proof material may be located intermediate the plastic and glass layers and reduce or slow the incidence of delamination between those layers. In particular embodiments the at least one glass and/or transparent plastic layer of the external layer is ceramic glass. In some embodiments, rear layer further comprises at least one glass layer. In some embodiments, the coating comprises Silicon dioxide, in particular wherein the Silicon dioxide is the predominant component of the coating. In some embodiments, the external layer comprises a transparent plastic layer sandwiched by a pair of glass layers. In some embodiments the transparent plastic layer is an adhesive plastic layer.

In accordance with embodiments of another aspect of the present invention, there is provided a method of producing a transparent armored composite structure comprising the steps of: (a) providing an external layer, comprising at least one glass and/or transparent plastic layer arranged to face toward an expected impact; (b) providing a rear layer, comprising a plastic layer; and (c) disposing the external layer and plastic layer spaced apart from each other via a spacing mechanism defining a space between the external and rear layers, wherein prior to step (c), the method comprises applying a moisture proof coating to the rear layer.

In some embodiments, wherein rear layer further comprises a glass layer adjacent the plastic layer, the method comprises arranging the glass and plastic layers so that the coating is intermediate those layers.

In accordance with embodiments of another aspect of the present invention, there is provided a transparent armored composite structure comprising: an external layer comprising at least one glass and/or transparent plastic layer arranged to face toward an expected impact; a rear layer comprising a plastic layer and a glass layer; and a spacing mechanism intermediate the external layer and the rear layer defining a space therebetween. In this embodiment, rear layer does not comprise coating.

In accordance with embodiments of another aspect of the present invention, there is provided a method of producing a transparent armored composite structure comprising the steps of: (a) providing an external layer, comprising at least one glass and/or transparent plastic layer arranged to face toward an expected impact; (b) providing a rear layer, comprising a plastic layer and glass layer adjacent one another ; and (c) disposing the external layer and rear layer spaced apart from each other via a spacing mechanism defining a space between the external and rear layers,

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be understood upon reading of the following detailed description of non-limiting exemplary embodiments thereof, with reference to the following drawings, in which:

Fig. 1 is a sectional view of an embodiment of an armored composite unit in accordance with the present invention; and Fig. 2 is a sectional view of another embodiment of the armored composite unit in accordance with the present invention.

The following detailed description of the invention refers to the accompanying drawings referred to above. Dimensions of components and features shown in the figures are chosen for convenience or clarity of presentation and are not necessarily shown to scale. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Fig. 1 shows an embodiment of a transparent armored composite structure of the invention comprising a protective transparent unit 10. In this embodiment, the protective transparent unit 10 comprises two spaced apart layers, an external layer 12 and a rear layer 14. External layer 12 comprises at least one transparent layer including one or more glass and/or plastic layers and typically has anti-ballistic properties. Rear layer 14 is typically disposed parallel to protective unit 12. In this embodiment, rear layer 14 comprises one layer, a plastic layer 24, e.g. polycarbonate or another transparent plastic layer which is suitable for preventing spalling, e.g. preventing shattering glass from entering the inner space of a vehicle, for example.

A spacing mechanism, comprising one or more spacing elements 16, holds external layer 12 and rear layer 14 spaced apart defining an air space 18 therebetween. The spacing element(s) 16 are typically in the shape of a frame and according to some embodiments comprise a moisture absorbing material or/and a moisture barrier, for example, hygroscopic rubber. In some embodiments, an adhesive plastic 21 , such as polyurethane, is applied over spacing elements 16 to attach external layer 12 to rear layer 14. The spacing mechanism provides a few advantages. One advantage is that the separation prevents delamination of the two layers 12 and 14, which commonly occurs when the two layers are adhered and are made of materials having different coefficients of expansion. Another advantage is that the space between the two layers 12 and 14 provides access to allow convenient replacement of rear layer 14 (typically the less expensive layer) without damaging external layer 12 (typically the more expensive layer, e.g. made of a ceramic glass or curved glass); although the external layer can also be replaced. A further advantage is that one of the two layers 12 or 14 can be removed (or replaced) in order to alleviate clouding caused by vapor within space 18. External layer 12 is an impact resistant layer for resisting projectiles, such as bullets. Typically, external layer 12 is positioned facing the expected projectile impact, represented by arrow 19. External layer 12 may be laminated or consist of one glass sheet. A laminated unit typically comprises two or more glass layers 20 interleaved with one or more plastic adhesive sheets 22, for example, as shown in Fig. 1 , wherein glass layers 20 sandwich plastic sheets 22. Plastic sheets 22 commonly comprise PVB (Polyvinyl butyral) or polyurethane sheets adhered to glass layers 20.

According to a particular embodiment, plastic layer 24 of rear layer 14 is coated with a film or coating 25 to help prevent moisture and/or debris from entering and accumulating between the layers, which may damage the optical transparency of the armored glass structure for example, by causing clouding. Coating 25 of plastic layer 24 is typically a transparent moisture proof or impermeable material. The material of coating 25 can be, for example, a gel applied to the plastic layer. Alternatively, the layer can be applied in the form of a spray, aerosol or any other form, covering plastic layer 24. Coating 25 can comprise, for example, a thin layer of Silicon dioxide, such as liquid glass, manufactured by "Nanopool" (76 Zum Felsacker Str., Schwalbach, Germany 66773). The coating 25 is disposed at least on the inner surface of plastic layer 24, e.g. the surface facing space 18. Fig. 2 shows another embodiment of an armored transparent composite unit wherein rear layer 14 comprises two layers, plastic layer 24 and a glass/plastic composite or glass layer 26. Plastic layer 24 commonly comprises polycarbonate, which is typically the outward facing layer thereof, and is adhered to glass layer 26. PVB (Polyvinyl butyral) and polyurethane are examples of suitable adhesives for such matter. This embodiment is particularly useful when the protective transparent unit 10 is not flat (i.e. curved, convex, concave or any other non-flat shape; for example in the case of front and rear vehicle windshields). Glass layer 26, attached to plastic layer 24, contributes to the support of the curved shape of the plastic layer which generally conforms to the form of the glass layer to which it is adhered.

When plastic layer 24 (generally, a polycarbonate layer) and glass layer 26 are adhered to each other, delamination may occur between those layers. Coating 25 is applied onto plastic layer 24 and arranged so that the coating abuts glass layer 26 to hinder such delamination. In some embodiments, coating 25 can be applied to glass layer 26. In some embodiments, coating 25 may be applied onto additional plastic and/or glass layers in order to provide additional delamination hindrance to protective transparent unit 10.

It should be understood that the above description is merely exemplary and that there are various embodiments of the present invention that may be devised, mutatis mutandis, and that the features described in the above-described embodiments, and those not described herein, may be used separately or in any suitable combination; and the invention can be devised in accordance with embodiments not necessarily described above.