EP1670732A2

EP1670732A2 - Improvements relating to glass

Info

Publication number: EP1670732A2
Application number: EP04768650A
Authority: EP
Inventors: Alfredo Fornieles
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-09-26
Filing date: 2004-09-27
Publication date: 2006-06-21
Also published as: WO2005030666A3; WO2005030666A2

Abstract

A process for the production of laminated kiln-fused glass comprising (a) applying a first bonding agent to a surface of the kiln-fused glass (b) allowing the first bonding agent to disperse over the surface of the kiln-fused glass so as to form an even surface over the kiln-fused glass; and (c) applying a support material to the even surface of the first bonding agent. The bonding agent may be applied as a series of coatings or alternatively with the help of a reservoir formed on the surface of the glass.

Description

IMPROVEMENTS RELATING TO GLASS

The present invention relates to glass. In particular, it relates to a method of laminating kiln-fused glass so that it can be used more safely in the field of architecture, and a laminated glass produced thereby.

Kiln-fused glass is essentially produced by melting together individual pieces of glass. Specifically, to produce kiln-fused glass, compatible pieces of fusible glass are arranged immediately next to each other and then heated in a kiln, typically to a temperature between 820 and 840 degrees Celsius. As the glass pieces are heated in the kiln, their viscosity decreases and they become soft and flow into each other. Upon cooling, the glass pieces bond with each other to form a kiln-fused glass piece.

It is believed that kiln-fused glass was first produced in the second millennium BC. The ancient Mesopotamians and Egyptians fused glass, as did the Greeks and the Romans. Although by the third century AD most glass-fusing techniques were almost forgotten, they were revived throughout Europe during the nineteenth century. More recently, in the mid nineteen seventies, a significant development in the area of fused glass came from the United States of America, with the commercial manufacture of glass specifically suited as raw material for glass fusing.

Kiln-fused glass is often highly decorative and, not least because of the increased availability of suitable raw materials, glass fusing is now a favourite method of creating decorative coloured glass. Decorative glass panels are, for instance, used in interior design and other architectural, domestic and commercial applications. A major limiting factor to the use of kiln-fused glass for these purposes has been safety. When kiln-fused glass breaks, it breaks, like any annealed glass, in large, jagged shards that can cause serious injury by cutting and piercing. Consequently, increasingly stringent building legislation across the world restricts the use of kiln-fused glass in areas where there is a high risk of breakage and injury such as in the home (for example in bathrooms and In doors panels) and at low heights in public buildings, such as schools. At present, kiln-fused glass has limited architectural uses. However, there is strong demand for materials such as kiln-fused glass in architecture and design due to their uniquely ornamental and aesthetic properties. There have been many attempts to make kiln-fused glass comply with safety regulations.

Attempts have been made to toughen kiln-fused glass via thermal tempering processes, which create balanced stresses and, when successful lead to toughened (or tempered) glass, which is typically assumed to be six times the strength of normal glass. Toughened glass is not only harder to break but also shatters into "safe" rounded pieces that are less likely to cause injury.

Unfortunately, the commercially available fusible glass that is used as raw material for manufacturing kiln-fused glass cannot be toughened: fusible glass generally contains air bubbles, which lead to cracks during the tempering process. This problem is exacerbated by the fusing process itself, which typically introduces even more air bubbles. In summary, the air content of the raw materials and air introduced during the fusing process eliminate toughening (by tempering) as a feasible method of treating kiln-fused glass to enhance its safety.

A second approach that is known in the art to improve safety is lamination. Laminated glass typically consists of two parallel sheets of glass and an intermediate interlayer with adequate adhesion to bond them together. Laminated glass is deemed to break safely, as during crack initiation, propagation, and ultimate fracture and failure, the glass fragments that are produced remain bonded to the interlayer of the laminated glass. As a result, laminating kiln-fused glass

■ with a second layer of glass theoretically enables kiln-fused glass to comply with building regulations.

Whilst lamination provides a potential solution to the problem of safety, it is technically difficult to implement. The most widely used processes for the production of laminated glass involves bonding together two glass panels having a parallel, regular surface topography, by using a film of polyvinyl butyral (PVB) as an interlayer. This method of lamination is complicated, expensive and time consuming, and usually involves the use of high temperature and pressure to suppress gas bubble formation in the film interlayer. Furthermore, it is extremely difficult to laminate uneven surfaces using a PVB film. The requirement for high temperatures and a flat even surface means that PVB lamination has not been deemed suitable for improving the safety of kiln- fused glass.

Due to the nature of the fusing process, kiln-fused glass pieces are generally not very even. In order to prevent the molten glass pieces from bonding to the kiln during fusing, heat resistant alumina silicate based ceramic fibreboards, ceramic fibre paper, kiln wash or a layer of sand are used as separators. Where the kiln-fused glass comes into contact with a separator during the fusing process, it has an uneven, textured surface. This presents an additional difficulty when attempting to laminate kiln-fused glass with PVB film.

Chemically curing resins have also been tried in attempts to laminate kiln-fused glass. These resins are typically pre-mixed and cold poured into a sealed void created between a kiln-fused glass sheet and a second sheet of glass by application of a thin double sided adhesive tape at the edge of both glass sheets. Laminators of standard float glass widely and successfully use this traditional method, but unfortunately this process when applied to kiln-fused glass is markedly less successful, with a high rate of failure due to the appearance of cracks or air pockets (delamination). Kiln-fiised glass and its backing sheet tend to be vulnerable to stresses caused during the formation of the sealed void, as the thin double sided tape forces together the not perfectly parallel edges and uneven surfaces of the two facing sheets of glass. Then, once the resin has been poured, the resin's adhesive forces combine with the uneven sealed void formed between the glass sheets to cause further asymmetric stresses during curing and consequential unbalanced shrinking of the resin interlayer. Typically resin shrinkage during curing varies from 4% to 10% by volume, depending on the manufacturer's formula; the total shrinkage of the resin interlayer at a given point is directly related to the thickness of the resin interlayer at that point. Since the uneven surface topography of the fused glass sheet means that the void between the fused glass and its backing/supporting sheet varies in thickness, the effect of shrinkage during curing is more pronounced in some areas of the laminated assembly than others. As a result, the uneven shrinkage of the resin interlayer causes localised stresses on the bonded glass sheets which leads to cracks and fractures in the laminated end product. Thus, conventional liquid resin lamination has, to date, been an impractical process for manufacturing laminated kiln-fused glass .

Hence, it is an object of the invention to provide improved methods for the production of a laminated kiln-fused glass, as well as laminated kiln-fused glass that is not subject to the drawbacks and disadvantages seen in the art.

The expression "kiln-fused glass" as used throughout this specification refers not only to kiln- fused glass as such but also encompasses other forms of glass that display uneven surface features and are therefore difficult to laminate. Examples of such forms of glass include kiln-fused glass, slumped glass and machine made patterned glass.

From a first aspect, the present invention resides in a process for the production of laminated kiln- fused glass comprising: (a) applying a first bonding agent to a surface of the kiln-fused glass; (b) allowing the first bonding agent to disperse over the surface of the kiln-fused glass so as to form an even surface over the kiln-fused glass; and (c) applying a support material to the even surface of the first bonding agent.

Preferably, the first bonding agent is applied to the surface of the kiln-fused glass as a plurality of coats, until said first bonding agent forms an even surface. The inventor has found that creating an even surface of bonding agent over the surface of a kiln-fused glass mitigates the asymmetric stresses otherwise caused by the uneven surface of kiln-fused glass during lamination. Thus, the present invention provides for a more effective process of production of laminated kiln-fused glass, during which breakages are less likely to occur.

To optimally prepare the support material, the process of the present invention may further comprise the step of applying at least one coat of a second bonding agent to a surface of the support material prior to applying the surface of the support material to the surface of the first bonding agent. The second bonding agent may be the same as the first bonding agent, or different. In any event it is beneficial to use sufficient first and second bonding agent to prevent contact between the kiln-fused glass and the support material. Analogously to the preparation of the kiln- fused glass, a plurality of coats of the second bonding agent may be applied to the surface of the support material, until said second bonding agent forms an even surface on the support material.

Advantageously, the first bonding agent may be curable. Where this is the case it is necessary to apply the support material whilst the surface of the first bonding agent is substantially uncured. The inventor has however determined that it can be beneficial to allow the first bonding agent to cure partially so as to bond to the surface of the kiln-fused glass before the support material is applied. An advantage associated with allowing the first bonding agent to cure partially (whilst its surface still remains uncured) is that this has the effect of evening out the surface of the kiln- fused glass: a uniformly thick layer of uncured resin is formed at the surface of the first bonding agent. Thus, according to the present invention, the resin interlayer acts both as an adhesive and a levelling agent. Partial curing prior to the application of the support material has the advantage of ensuring that most of the curing shrinkage occurs before the supporting material is applied, which reduces the stresses between the kiln-fused glass and the support material.

A preferred way of enabling the surface of the first bonding agent to remain substantially uncured is to employ a resin that cures in the absence of oxygen as the first bonding agent. Such a resin may also be allowed to cure partially so as to bond to the surface of the kiln-fused glass before the support material is applied (although the first bonding agent remains substantially uncured at its surface until the support material is applied). A particularly suitable resin for use in the invention is an unsaturated polyester in styrene mixed with organosilane ester at 1% by volume and with an organic peroxide at 1% by volume.

Since the formation of air bubbles between the kiln-fused glass and the supporting material is undesirable, it is preferred that the support material is applied to the first bonding agent such that substantially no air is trapped between the kiln-fused glass and the supporting material. One method of avoiding trapped air is to use a squeegee or similar device such as a rubber roller to squeeze out any air bubbles. The formation of air bubbles can also be counteracted by angling the support material with respect to the kiln-fused glass, bringing a part of the perimeter of the support material into contact with the first bonding agent, and gradually lowering the support material towards the kiln-fused glass to bring a surface of the support material fully into contact with the first bonding material whilst eliminating substantially all air between the kiln- fused glass and the support material.

As an alternative to applying one or more coats of the first bonding material to create an even surface, a reservoir may be provided on the surface of the kiln- fused glass so as to contain the first bonding agent therein, the reservoir being defined by a lower surface corresponding to the surface of the kiln-fused glass, and at least one perimeter boundary. Employing a reservoir to hold the first bonding agent is particularly advantageous when very strong adhesion is required, for example where the kiln-fused glass or the support material is heavy and/or when the surface of the kiln-fused glass is particularly uneven.

Preferably, a perimeter boundary of the reservoir extends along the perimeter of the kiln-fused glass in order to maximise the bonding area between the kiln-fused glass and the support material.

Where a reservoir is used, it is advantageous to apply the supporting material such that a gap filled with bonding agent is formed between the perimeter of the supporting material and the perimeter of the reservoir.

The perimeter boundary may be integral with the kiln-fused glass, such as by means of a ridge on the surface of the kiln-fused glass. Conveniently, the reservoir can be formed by heating the kiln- fused glass or fusible glass and allowing the glass to flow into or over a reservoir-forming mould. Alternatively, a perimeter boundary may be provided by adhering a wall member, such as an extrusion to a surface of the kiln-fused glass. For example, the reservoir can be made by the application of a shaped flexible foam extrusion or soft rubber extrusion that features a self- adhesive surface, which is applied to the perimeter of the first panel in a continuous manner to form a complete ridge or frame to the perimeter. This temporary ridge can be removed when the laminating process is completed and the first bonding agent is fully cured or it can remain in place as a finishing feature of the laminated product.

A reservoir may be provided on the surface of the support material, as an alternative or an addition to a reservoir on the kiln-fused glass, to contain the second bonding agent therein, the reservoir being defined by a lower surface corresponding to the surface of the support material, and at least one perimeter boundary.

Conveniently, the support material may be selected from a group containing toughened glass, kiln fused glass and float glass. It may also be advantageous to incorporate steel connectors into the support material. Alternatively, the support material may be flexible, for example in the form of a an impact resistant film. In some situations the use of optically clear polyester is beneficial.

Expressed in another way, the invention also resides in a process for the production of laminated kiln-fused glass comprising: (a) applying a first bonding agent to a surface of the kiln-fused glass; (b) allowing the first bonding agent to cure partially so as to bond to the surface of the kiln-fused glass (c) allowing the partially cured first bonding agent to disperse over the surface of the kiln- fused glass so as to form an even surface on the kiln-fused glass; and (d) applying a support material to the even surface whilst the even surface remains substantially uncured.

As previously discussed, the first bonding agent may be applied as a coating or by use of a reservoir, with associated options as set out in the appending claims.

From another aspect, the invention resides in a laminated glass panel comprising: a kiln-fused glass layer; an intermediate bonding layer; and a support material layer; characterised in that the intermediate bonding layer is located between the kiln-fused glass layer and the support material layer, and wherein the intermediate bonding layer occupies the interstices between the kiln-fused glass layer and the support material layer. The bonding layer preferably comprises a resin that cures in the absence of oxygen, such as an unsaturated polyester in styrene mixed with organosilane ester at 1% by volume and with an organic peroxide at 1% by volume.

The support layer may be rigid, for example being formed from toughened glass, kiln fused glass or float glass or flexible, for example in the form of an impact resistant film.

It will be appreciated that the invention provides a process for laminating kiln-fused glass whereby chemical cured resin is used without the need for a sealed void between the kiln-fused glass and the backing glass, but by utilising the resin to form a semi-hardened layer which fills all the unevenness of the kiln-fused glass creating a de-stressed surface ready to receive the backing panel or backing material. This process not only allows the lamination of flat kiln-fused panels but also curved or undulating panels. For laminating kiln-fused flat panels an open reservoir may be utilised, which is formed in the kiln-fused glass during the fusing process or by fitting to the perimeter of the panel a ridge made of suitable materials. For curved or undulating kiln-fused panels it is advantageous to apply the resin as coatings on the uneven surface of the kiln-fused glass allowing for the resin to semi-harden prior to the application of the subsequent coatings until an even coated surface has been achieved. This second method can of course also be used with flat kiln-fused panels.

A further advantage of the present invention is that it provides a laminated glass product that incorporates kiln-fused glass and toughened glass which itself can be used as a load carrying element in architectural glazing systems and other architectural applications such as balustrades, panels and roof covers, as well furniture and interior elements.

The processes of the invention relate not only to the lamination of flat surfaces but also to contoured or undulating surfaces. In the latter case, it may be convenient to form a solid supporting material to the exact contours and geometry of the kiln-fused glass. This can be achieved by laying the supporting material and the kiln-fused glass together during a shaping process (for example by the process of slumping). It should be noted that the term "panel" wherever used herein refers not only to sheets of material, rigid or flexible, but also to blocks and slabs and is not restricted to substantially rectangular or even shapes. Accordingly, the term should be construed broadly throughout. The invention has particular application to decorative panels, especially decorative panels, but not limited thereto.

The present invention provides for laminated kiln-fused glass that displays significant advantages such as attenuation of acoustic noise, greatly improved safety and the further enhancement of the aesthetic appeal of glass suitable for use in a wide range of architectural applications.

In order that this invention may be more readily understood, reference will now be made, by way of example, to Figures 1 to 12 of the accompanying drawings in which:

Figure 1 is a view in section of a fused glass panel and a ceramic fϊbreboard mould for forming a resin reservoir on the fused glass panel, prior to the moulding process;

Figure 2 is a view in section of the fused glass panel and ceramic fϊbreboard mould of Figure 1, after the moulding process; Figure 3 is a view in section of a fused glass panel and an alternative, ceramic fibre paper based mould for forming a resin reservoir on the fused glass panel, after the moulding process;

Figure 4 is a view in section of a fused glass panel having a reservoir filled with resin;

Figure 5 is a view in section of the fused glass panel of Figure 4 with a backing sheet positioned in the resin reservoir; Figure 6 is a view in section of the fused glass panel of Figure 4 with a toughened glass and steel connector positioned in the resin reservoir;

Figure 7 is a view in section of the fused glass panel of Figure 4 with a second fused glass panel, having a second reservoir filled with resin and a backing sheet, positioned in the resin reservoir;

Figure 8 is a front view of a toughened glass door incorporating a fused glass panel;

Figure 9 is a partial view in section of the toughened glass door of Figure 8;

Figure 10 is a view in section of a tabletop assembly incorporating a fused glass panel; Figure 11 is a view in section of a curtain wall incorporating a fused glass panel; and

Figure 12 is a view in section of a horizontal and a vertical glass assembly incorporating a fused glass panel.

Description of the preferred Embodiments:

Referring firstly to Figures 1 to 5, according to one embodiment of the invention, a panel of kiln- fused glass (1) is laminated by perfonning the basic steps of (i) forming an open reservoir on a surface of the kiln-fused glass panel (1), (ii) filling the reservoir with chemically curing resin (6), and (iii) bonding a backing glass sheet (12) to the panel of kiln-fused glass (1) by applying the backing glass sheet (8) to the resin (6). Each of these three basic steps will now be described in detail. Referring to Figures 1 and 2, an open reservoir is formed on a panel of kiln-fused (1) glass by creating a contiguous ridge (4) on one of its surfaces. The ridge (4) is formed so that it defines the perimeter of the area that is to be laminated. Typically, if the entire sheet of kiln-fused glass (1) is to be laminated, the ridge (4) is formed close to the edge of the glass sheet (1). The ridge (4) is formed with the aid of a ceramic fibreboard mould (2) which comprises a substantially horizontal surface and a contiguous groove (3) (inverted ridge) routed therein, the groove (3) being suitable for defining the contiguous ridge (4) on the kiln-fused glass. Specifically, fusible glass pieces (1) are placed on the substantially horizontal surface of the ceramic fibreboard mould (2), where they are heated until they reach their full-fuse temperature of around 820 to 840 degrees Celsius. As shown in Figure 2, at full fuse temperature, the viscosity of the fusible glass pieces (1) decreases and they fuse with each other to form a kiln-fused glass panel (1) which, due to the effect of gravity, also fills up (i.e. flows/extends into) the groove (3) in the ceramic fibreboard mould (2). Upon cooling, a solid kiln-fused glass panel (1) is created, having a contiguous perimeter ridge (4) defined by the contiguous grove (3) in the fibreboard mould. It is preferred that the ridge (4) be substantially continuous around the perimeter of the glass panel. However, alternative boundary measures can be suitably adopted such as grooves and intermittent raised edges. Of course the precise position shape and size of the contiguous ridge (4) on the kiln-fused glass panel is determined by the size, orientation and position of the contiguous groove (3) in the ceramic fibreboard mould (2). It is generally beneficial to create as large a reservoir as practicable in terms of its surface by arranging the contiguous groove (3) and fused glass (1) to form a contiguous ridge running (4) just inside the perimeter of the kiln-fused glass panel (1).

An alternative method of creating a reservoir-defining ridge on the kiln-fused glass panel (1) is illustrated in Figure 3. Here fusible glass pieces (1) are positioned on top of a layer of ceramic fibre paper (5) which is smaller than the footprint of the eventual final kiln-fused glass piece (1), so as to elevate them above a bottom shelf. When the glass pieces (1) reach full-fusing temperature they soften and flow into each other and over the edges of the fibre paper (5) to form a kiln-fused glass panel (1) with a cavity (or reservoir) corresponding to the thickness of the ceramic fibre paper. Needless to say there are countless other types of moulds that can be used to create contiguous ridges for forming reservoirs. However, whichever type of mould is chosen, it should be ensured that the ridge that is formed has an appropriate height and shape for forming the boundary of the reservoir. It is beneficial if the extent of protrusion of the ridge from the fused panel relates directly to the thickness of the envisaged lamination interlayer.

It should be noted that the step of fonning a ridge defining a reservoir on a fused glass panel can also be perfonned by re-fusing; it is possible to use both types of moulds described above on a ready made glass panel, for example a finished kiln-fused glass panel wherein individual pieces of glass have already been joined together by a previous fusing process. Any fusible glass panel can be placed on the chosen mould and heated until its viscosity decreases to form an appropriate ridge/reservoir. In such a way, the reservoir is effectively imprinted into the kiln-fused glass panel.

Turning to the second basic step of the lamination process, and referring to Figure 4, once the fusing (and ridge/reservoir formation) process has been completed, the kiln-fused glass (1) is turned over and brought into a horizontal position, with the reservoir facing upwards. The cavity formed by either of the moulding processes described above, acts as an open reservoir into which pre-mixed chemically curing resin (6) is poured. The resin (6) used in this embodiment of the invention is unsaturated polyester in styrene available under the trade name "Safety Plus®" from Glasslam N.G.I., Inc. Prior to application, the resin is stirred and mixed with organosilane ester at 1% by volume and with organic peroxide (Methyl Ethyl Ketone Peroxide in solution with no more than 9% by weight of active oxygen) at 1% by volume, at a temperature between 20 to 22 degrees Celsius. The open reservoir is filled until the resin mixture (6) completely covers the bottom of the reservoir. It is reiterated that the surface of the kiln-fused glass (1) that defines the bottom of the reservoir is uneven because it is typically the surface of the kiln-fused glass panel (1) that was in contact with the mould (2; 5) during fusion. Referring to Figure 5, the specific amount of resin mixture (6) filled into the reservoir is dependent upon (i) the required or intended final application of the laminated panel, (ii) the overall size of the finished panel and (iii) the thickness of the backing/supporting glass sheet (8). For example, more resin (6) is required if the end product laminated panel is intended to support a lot of weight or if the backing sheet (8) is very thick and heavy. Hence, for architectural glass certain modifications will be necessary in order to ensure the strength of the laminated panel is sufficient for the application it is to be put to. Similarly, a very large kiln-fused glass panel (1) obviously requires particularly strong adhesion to the backing sheet (8) since it is very heavy, which means an appropriately large amount of resin (6) should be used. In any event, the reservoir is always filled far enough for the upper surface of the resin (6) to be substantially level (i.e. planar) and entirely clear of the reservoir bottom.

Once the pre-mixed resin (6) has been poured into the reservoir, the curing process begins. The time required for curing varies, depending on the ambient temperature. Under some processing conditions, it is useful to expose the resin (6) in the filled reservoir to some limited increased heat (e.g. 35 degrees Celsius) to reduce the curing time. Crucially, one of the characteristics of the resin (6) used in this embodiment of the invention is that as long as it is in contact with oxygen (air) it does not cure; it remains in a viscous and tacky condition until it is deprived of air or is exposed to further chemical cure. As a result of this characteristic, the resin (6) develops adhesion and bonds to the solid substrates, the bottom and the sides of the reservoir, but remains substantially uncured at its flat upper surface (where it is in contact with air). This effect essentially evens out the surface of the kiln-fused glass (1): the resin fills and begins to cure in particularly deep parts of the reservoir; but where the reservoir is shallower, the curing resin layer (6) is thinner. A uniformly thick layer of uncured resin is formed at the surface of the resin layer (6). Thus, according to the present invention, the resin interlayer (6) acts both as an adhesive and a levelling agent.

As discussed above, chemically curing resins shrink during curing. Since the magnitude of shrinkage is directly related to the volume of resin (6), the surface level of the resin (6) initially drops more in deeper areas of the reservoir. This is however compensated by the effect of gravity on the semi-cured resin (6), which is still viscous enough to maintain fluid properties and flows around the reservoir to maintain an even, level top surface. In summary, pre-assembly curing and shrinkage form a semi-hardened resin bed (6), which fills all unevenness of the kiln-fused glass surface, and self levels, leaving an even and de-stressed surface to receive a backing glass sheet (8). The creation of this even and de-stressed surface avoids the asymmetric stresses caused by resin shrinkage in conventional liquid lamination.

Moving to the third and final basic step in the lamination process, and referring again to Figure 5, the surface of backing glass sheet support (8), which is to come into contact with the semi-cured resin (6) in the reservoir, is fully primed by brushing a thin layer of newly mixed resin onto it. The backing glass sheet (8) is typically sized smaller than the internal size of the reservoir so as to leave a continuous open space (trough) (7) between the external edges of the backing glass sheet (8) and the internal edges of the reservoir's ridge (4). Since it is important to prevent air from being trapped in the resin layer (6), the backing glass sheet is suitably applied to the resin reservoir in such a way as to avoid gas/air bubbles becoming trapped in the resin (6). This can for instance be achieved: by angling the backing sheet (8) at 45 degrees to the surface of the reservoir and then slowly lowering the backing sheet (8) downwards towards the reservoir, so as enable the resin (6) to push out all air. Once the backing glass sheet (8) is fully lowered and temporarily secured in position (for example with adhesive tape), the thin layer of new resin applied to the backing sheet and the absence of air ensures the full curing of all the resin (6) between the fused glass (1) and the backing glass sheet (8). The shrinkage that occurs during this curing is relatively small - the asymmetric topographies of the kiln-fused glass (1) and of the backing glass sheet (8) pose much less of a problem and asymmetric stresses are reduced significantly. This results in a much higher and acceptable degree of success in safety lamination with kiln-fused glass. Once the kiln-fused glass (1) is firmly bonded to its backing glass sheet (8), the remainder of the uncured resin, which remains within the top of the trough (7), is cut back to the cured level underneath, thus removing the last viscous element of the assembly. The exposed surface can then be suitably sealed with compatible silicone (not shown).

Once curing is complete (i.e. assembly of the laminated kiln-fused glass is finished), any edges extending beyond the laminated area can be sawn back to the laminated area. Alternatively the laminated kiln-fused glass can be cut to a required size, provided the backing sheet is not made of toughened glass, which might shatter. The above description of a first embodiment of the invention is, of course, not the only way of implementing the present invention. It is also possible to perform a lamination procedure with the help of a reservoir for resin that is not integral with the kiln-fused glass panel (1); the ridges of the reservoir do not have to be part of the glass (1) itself. A non-integral reservoir can be created with a flexible extrusion adhered to the surface of the glass or a frame, made for example of wood, which is placed on top of the glass. Similarly, it is not essential for the reservoir to be formed in or on a kiln-fused glass panel - it can be formed in other materials such as glass or wood, a point which is discussed further below with reference to the various applications of laminated kiln- fused glass.

Before moving on to a discussion of the applications of laminated kiln-fused glass and how the lamination process can be adapted to cater for them, a second embodiment of the invention will now be described. It will be appreciated that the lamination method of the first embodiment is only effective where lamination occurs along a substantially level surface; the reservoir cannot perform its function of evening out the asymmetric surface topography characteristics of kiln- fused glass when it is formed on a curved or undulating panel. By contrast, the lamination method of the second embodiment is designed to allow lamination of surfaces of any shape. It comprises the basic steps of (i) applying a first layer of chemically curing resin to a surface of a kiln-fused glass panel and allowing said resin layer to cure partially (ii) applying, as required, further layers of resin, which are also allowed to cure partially and (iii) bonding a backing glass sheet to the panel of kiln-fused glass by applying the backing glass sheet to the resin layer(s). The lamination method of the second embodiment is possible because chemically cured resin mixtures (such as that described in respect of the first embodiment) hold enough adherent viscosity so as to be applied to the uneven surface of a kiln-fused glass piece and to remain attached without reservoir boundaries.

Turning to a more detailed description of the basic steps of the second embodiment of the invention, once the fusing process and the curving or shaping of a kiln-fused glass panel has been completed, it is placed in a stable position so that the lamination process can begin. Then, a first coat of resin mixture (resin) is applied to the surface that is to be laminated, for example with a brush. The resin mixture is the same as that used in the first embodiment and therefore has the property of not curing when in contact with oxygen (air); it remains in a viscous and tacky condition until it is deprived of air or is exposed to further chemical cure. As a result, the first coat of resin mixture will cure partly, adhering to the substrate but remaining substantially uncured at its own surface, where it is exposed to oxygen (air).

It will be appreciated that the effect of a partly cured coat of resin is analogous to that of a partly cured reservoir of resin: the coat of resin works towards evening out any unevenness in the topography of the surface to which it is applied just as a resin reservoir does. However, since the coat of resin has far less volume than a resin reservoir, it is likely that it cannot completely even out and de-stress the uneven surface to which it is applied; a single coat of resin could only perform this function by itself if applied to a surface that is only fractionally uneven - which, in the context of kiln-fused glass, is unlikely to be the case. Consequently, once the first coat of resin has cured partially, a second coat of resin is brushed onto its surface, which is also allowed to cure partially, where it is not in contact with air. The second coat further fills in any irregular topography that may still be present after application of the first coat and thus further contributes to creating a smooth, de-stressed surface, again in the same manner as described above for the resin reservoir. The process of applying consecutive coats of resin and allowing them to cure partially, where they are not in contact with air, is repeated until a regular, reasonably smooth surface of uncured resin is created. The resin then forms a de-stressed semi-hardened resin bed suitable for receiving a supportive backing panel. It should be noted that, as in the first embodiment, most of the curing shrinkage occurs before the backing panel is applied, which means that asymmetric stresses are avoided to a great extent.

Where a curved or undulating panel is to be laminated the choice of a backing panel/material is more difficult than in cases where lamination of a flat surface occurs. Clearly, any backing material has to match the shape of the panel that is to be laminated. The inventor has found that two types of backing materials are particularly appropriate for curved or undulating surfaces. The first of these involves the use of a flexible material, such as Madico Proteckt^® security film, an optically clear impact resistant polyester film, as a backing. Prior to the application of such a film, a coat of uncured resin is applied to the semi-hardened resin already attached to the surface of the kiln- fused glass panel. The flexible film is then applied by angling it with respect to the kiln-fused glass panel, bringing its perimeter into contact with the resin and slowly lowering it towards the kiln-fused glass panel to bring the surface of the film fully into contact with the resin whilst substantially eliminating air pockets trapped between the film and the kiln-fused glass. To remove any remaining air after application of the film, a squeegee or similar device such as a rubber roller, is applied to the upper surface of the film (i.e. the surface not in contact with the adhesive) to squeeze out air bubbles and surplus resin. The resin is then allowed to cure fully to complete lamination.

The great advantage associated with the use of flexible film as backing material is ease of application: the film is relatively thin (typically between 100 and 400 microns), malleable and can easily adapt to the contours and geometry of a glass surface. Furthermore, despite their thinness, optically clear impact resistant films such as Madico Proteckt^® are able to provide enhanced shatter resistance and safe breakage qualities to any glass they are applied to. Such films are known for use in laminating flat fabricated float glass, but under normal circumstances could not be applied to kiln-fused glass (due to its uneven surfaces). The lamination method of the second embodiment provides for the successful application of flexible security films to uneven surfaces.

In situations where it is desirable to avoid the use of flexible security films, it is possible to create an appropriate backing panel made of glass by the known process of slumping. Slumping essentially involves placing the backing panel immediately next to (but separated from) the panel that is to be laminated during a shaping process. It is generally done by heating the two glass pieces that are to attain the same shape together, on top of a mould of the required shape, but separating them from each other by means of a thin layer of kiln fibre or an even sprinkling of dust separator. Once both pieces have adapted to the shape of the mould, they have roughly the same shape and a surface that coincides in geometry with the other piece. The slumping process leads to a situation in which the laminating surface of both the kiln-fused glass and the backing sheet is uneven. Consequently, it is necessary to apply layers of resin, as described above, to both the kiln-fused glass and the backing sheet, to create two substantively even and de-stressed surfaces (after partial curing and shrinkage) that can be used for bonding. Once the kiln-fused glass and the backing sheet have been prepared in this way, a further coat of uncured resin is applied to the relevant surfaces of the two panels. Then, the backing panel is slowly lowered onto to the kiln-fused panel while further uncured resin is poured in between them. The perimeter edges of the panels are left free to allow for surplus resin and air to flow out. After the surfaces of the two panels are in contact, further pressure is applied so as to remove surplus resin material and air - only a very thin layer of uncured resin remains trapped by capillarity between the two partially cured coats of resin formed on the surfaces of the panels. The resin is then finally allowed to cure fully to complete lamination.

Two basic ways of implementing the present invention have been described above and it should be appreciated that the methods of both embodiments can be modified, as required. Thus, it is, possible for example, to carry out lamination with virtually any type of support material, such as glass, plastics, metal or wood.

An example that illustrates the versatility of the present invention is shown in Figure 6. In current architectural use, glass has become a load-carrying element in contemporary building enclosures, resisting design loads traditionally supported by materials such as steel, wood or concrete. Figure

6 illustrates how a kiln-fused glass (1), with all its aesthetic qualities but despite the inherent safety problems, can be laminated to become capable of carrying structural loads in architecture.

Load-canying laminated kiln-fused glass can be created by either of the processes described above, with the backing sheet taking the form of a monolithic toughened (tempered) glass (10) into which steel connectors (9) are incorporated and secured prior to the laminating process. The toughened glass (10) is predrilled with countersunk holes where the steel connectors (9) are tightened to the glass by means of a threaded locking washer (not shown) and presents a flush, substantially flat surface on one side, which is placed in contact with the resin (6) on the kiln- fused glass (1) during the lamination process. Once the laminating process is completed, the glass unit thus assembled and laminated can be used as a structural/architectural component. Load capacity can be supported by the monolithic toughened (tempered) glass (10) and transferred through the steel connector (10) to a suitable supporting structure. The kiln-fused glass (1) acts as an aesthetic outer layer, which in itself is not put under undue stresses, whilst complying with building regulations and safety standards.

Figure 7 illustrates a further way of adapting the lamination processes described above. Here, a multilayered structure is created by laminating a first glass panel (1) with a second glass panel (8), which is in turn laminated with a third glass panel (11). Although in this case the lamination was carried out by using reservoirs in the first and second panels, it is of course also possible to create such multilayered structures using the coat-by-coat method of the second embodiment. A structure having three layers, like that shown in Figure 7, is not only stronger than a structure with two layers but may also be more aesthetically pleasing since the colours and effects of three glass panels can be combined in a single sheet.

Due to the aesthetic qualities of kiln-fused glass, it is desirable to incorporate it into objects such as furniture. Since the present invention provides a way of making kiln-fused glass comply with safety regulations there are fewer restrictions on doing this. Figures 8 and 9 illustrate a way in which a fused glass panel (12) can be laminated by, and at the same time embedded into, a door having a door handle (13) with a toughened glass frame (14). Referring to Figure 9, a reservoir is formed in the toughened glass frame (14) of the door which is filled and semi-cured as described in respect of the first embodiment above. A surface of the kiln-fused glass (12), which essentially performs the role taken by the backing glass sheet in the first embodiment, is then prepared by applying and semi-curing several coats of resin, and is lowered onto the resin (6) in the reservoir after a final coating. The laminating process is then completed as detailed for the first embodiment above, the end result being a door with an embedded, laminated panel of fused glass (12). Similarly, in Figure 10 a piece of kiln-fused glass (12) is embedded into the underside of a glass table (16) using a reservoir formed therein. Both the door and the table top have in this case been created with the help of a reservoir of resin (formed in the toughened glass frame of the door and the glass table top respectively). However, alternatively, the method of the second embodiment could have been used instead. As mentioned above, the coat-by-coat method of the second embodiment is extremely flexible and works on a whole host of materials. Virtually any material (e.g. wood, metal, glass, plastic, stone) that has an uneven surface can be levelled and prepared for lamination by use of this method.

The laminating process according to the invention can be also incorporated in a variety of end uses such as curtain walling, doors, roofs, divider walls, furniture, and thereby allow kiln-fused glass panels to comply with safety requirements, thus allowing for this hitherto rarely used material to be employed in a wide range of design and architectural applications. Figure 11, for instance shows a curtain wall (17) supported by a base (18) and made of toughened glass, which is imbedded with (and at the same time effectively laminates) a kiln-fused glass panel (12). Figure 12 shows a horizontal and vertical glass assembly comprising two kiln-fused glass panels (12) embedded in toughened glass (19, 20) held together at right angles by steel connectors (21).

Although the prefened embodiments have been disclosed herein, it is appreciated that various changes and modification may be made thereto without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

Claims:

1. A process for the production of laminated kiln- fused glass comprising: a) applying a first bonding agent to a surface of the kiln-fused glass; b) allowing the first bonding agent to disperse over the surface of the kiln-fused glass so as to form an even surface over the kiln-fused glass; and c) applying a support material to the even surface of the first bonding agent.

2. A process according to claim 1, wherein the first bonding agent is applied to the surface of the kiln-fused glass as a plurality of coats, until said first bonding agent forms an even surface.

3. A process according to claims 1 or 2, further comprising the step of applying at least one coat of a second bonding agent to a surface of the support material prior to applying the surface of the support material to the surface of the first bonding agent.

4. A process according to claim 3, wherein a plurality of coats of the second bonding agent are applied to the surface of the support material, until said second bonding agent forms an even surface on the support material.

5. A process according to any previous claim wherein the first bonding agent is curable and wherein the support material is applied whilst the surface of the first bonding agent is substantially uncured.

6. A process according to claim 5 wherein the first bonding agent is allowed to cure partially so as to bond to the surface of the kiln-fused glass before the support material is applied.

7. A process according to claims 5 or 6 wherein the first bonding agent is a resin that cures in the absence of oxygen.

8. A process according to any one of claims 5 to 7 wherein the bonding agent is unsaturated polyester in styrene mixed with organosilane ester at 1% by volume and with an organic peroxide at 1% by volume.

9. A process according to any preceding claim wherein the support material is applied to the first bonding agent such that substantially no air is trapped between the kiln-fused glass and the supporting material.

10. A process according to claim 9 wherein the support material is applied by: angling the support material with respect to the kiln-fused glass, bringing a part of the perimeter of the support material into contact with the first bonding agent, and gradually lowering the support material towards the kiln-fused glass to bring a surface of the support material fully into contact with the first bonding material whilst eliminating substantially all air between the kiln-fused glass and the support material.

11. A process according to any previous claim wherein a reservoir is provided on the surface of the kiln-fused glass so as to contain the first bonding agent therein, the reservoir being defined by a lower surface conesponding to the surface of the kiln-fused glass, and at least one perimeter boundary.

12. A process according to claim 11 wherein a perimeter boundary of the reservoir extends along the perimeter of the kiln-fused glass.

13. A process according to claim 11 or 12 wherein a perimeter boundary of the reservoir is integral with the kiln-fused glass.

14. A process according to claim 13 wherein a perimeter boundary of the reservoir comprises a ridge on the surface of the kiln-fused glass.

15. A process according to any one of claims 11 to 14 wherein the reservoir is formed by heating the kiln-fused glass or fusible glass and allowing the glass to flow into or over a reservoir- forming mould.

16. A process according to claims 11 or 12 wherein a perimeter boundary is provided by adhering a wall member, such as an extrusion to a surface of the kiln-fused glass.

17. A process according to claim 3, when dependent on claim 1, wherein a reservoir is provided on the surface of the support material so as to contain the second bonding agent therein, the reservoir being defined by a lower surface conesponding to the surface of the support material, and at least one perimeter boundary.

18. A process according to claim 17 wherein a perimeter boundary of the reservoir extends along the perimeter of the support material.

19. A process according to claims 17 or 18 wherein a perimeter boundary of the reservoir is integral with the support material.

20. A process according to claim 19 wherein a perimeter boundary of the reservoir comprises a ridge on the surface of the support material.

21. A process according to claims 17 or 18 wherein a perimeter boundary is provided by adhering a wall member, such as an extrusion to a surface of the support material.

22. A process according to any preceding claim wherein the support material is selected from a group containing toughened glass, kiln fused glass and float glass.

23. A process according to any preceding claim wherein steel connectors are incorporated into the support material.

24. A process according to any one of claims 1 to 21 wherein the support material is flexible.

25. A process according to claim 24 wherein the support material is an impact resistant film.

26. A process according to claim 25 wherein the impact resistant film is made of polyester and is optically clear.

27. A process for the production of laminated kiln-fused glass comprising: a) applying a first bonding agent to a surface of the kiln-fused glass; b) allowing the first bonding agent to cure partially so as to bond to the surface of the kiln-fused glass; c) allowing the partially cured first bonding agent to disperse over the surface of the kiln- fused glass so as to form an even surface on the kiln-fused glass; and d) applying a support material to the even surface whilst the even surface remains substantially uncured.

28. A process according to claim 27, wherein the first bonding agent is applied to the surface of the kiln-fused glass as a plurality of coats, until said first bonding agent forms an even surface.

29. A process according to claim 28 wherein each coat of the first bonding agent is allowed to cure partially before a subsequent coat or the support material is applied.

30. A process according to any one of claims 27 to 30, further comprising the step of applying at least one coat of a second bonding agent to a surface of the support material prior to applying the surface of the support material to the surface of the first bonding agent.

31. A process according to claim 30, wherein a plurality of coats of the second bonding agent are applied to the surface of the support material, until said second bonding agent forms an even surface on the support material.

32. A process according to any one of claims 27 to 31 wherein the support material is applied whilst the surface of the first bonding agent is substantially uncured.

33. A process according to any one of claims 27 to 32 wherein the first bonding agent is a resin that cures in the absence of oxygen.

34. A process according to claim 33 wherein the bonding agent is unsaturated polyester in styrene mixed with organosilane ester at 1% by volume and with an organic peroxide at 1% by volume.

35. A process according to any one of claims 27 to 34 wherein the support material is applied to the first bonding agent such that substantially no air is trapped between the kiln-fused glass and the supporting material.

36. A process according to claim 35 wherein the support material is applied by: angling the support material with respect to the kiln-fused glass, bringing a part of the perimeter of the support material into contact with the first bonding agent, and gradually lowering the support material towards the kiln-fused glass to bring a surface of the support material fully into contact with the first bonding material whilst eliminating substantially all air between the kiln-fused glass and the support material.

37. A process according to any one of claims 27 to 36 wherein a reservoir is provided on the surface of the kiln-fused glass so as to contain the first bonding agent therein, the reservoir being defined by a lower surface conesponding to the surface of the kiln-fused glass, and at least one perimeter boundary.

38. A process according to claim 37 wherein a perimeter boundary of the reservoir extends along the perimeter of the kiln-fused glass.

39. A process according to claim 37 or 38 wherein a perimeter boundary of the reservoir is integral with the kiln-fused glass.

40. A process according to claim 39 wherein a perimeter boundary of the reservoir comprises a ridge on the surface of the kiln- fused glass.

41. A process according to any one of claims 37 to 40 wherein the reservoir is formed by heating the kiln-fused glass or fused glass and allowing the glass to flow into or over a reservoir- forming mould.

42. A process according to claims 37 or 38 wherein the perimeter boundary is provided by adhering a wall member, such as an extrusion to a surface of the kiln-fused glass.

43. A process according to claim 30, when dependent on claim 27, wherein a reservoir is provided on the surface of the support material so as to contain the second bonding agent therein, the reservoir being defined by a lower surface conesponding to the surface of the support material, and at least one perimeter boundary.

44. A process according to claim 43 wherein a perimeter boundary of the reservoir extends along the perimeter of the support material.

45. A process according to claims 43 or 44 wherein a perimeter boundary of the reservoir is integral with the support material.

46. A process according to claim 45 wherein a perimeter boundary of the reservoir comprises a ridge on the surface of the support material.

47. A process according to claims 43 or 44 wherein a perimeter boundary is provided by adhering a wall member, such as an extrusion to a surface of the support material.

48. A process according to any one of claims 27 to 47 wherein the support material is selected from a group containing toughened glass, kiln fused glass and float glass.

49. A process according to any one of claims 27 to 47 wherein steel connectors are incorporated into the support material.

50. A process according to any one of claims 27 to 42 wherein the support material is flexible.

51. A process according to claim 48 wherein the support material is an impact resistant film.

52. A process according to claim 49 wherein the impact resistant film is made of polyester and is optically clear.

53. A laminated glass panel comprising: a kiln-fused glass layer; an intermediate bonding layer; and a support material layer

characterised in that the intermediate bonding layer is located between the kiln-fused glass layer and the support material layer, and wherein the intermediate bonding layer occupies the interstices between the kiln-fused glass layer and the support material layer.

54. A laminated glass panel according to claim 53 wherein the bonding layer is formed by a resin that cures in the absence of oxygen

55. A laminated glass panel according to claim 54 wherein the bonding layer is formed by unsaturated polyester in styrene mixed with organosilane ester at 1% by volume and with an organic peroxide at 1% by volume.

56. A laminated glass panel according to any one of claims 53 to 55 wherein the support layer is rigid.

57. A laminated glass panel according to any one of claims 53 to 56 wherein the support layer is selected from a group containing toughened glass, kiln fused glass and float glass.