By Chris Davis, composites manager at H B Fuller:Kommerling and Vice Chairman of the GGF Laminators and Tougheners committee
Look at any international city’s newest buildings and they will undoubtedly be architectural wonders, built predominantly from glass, with a steel framework. Whilst we all feel better on a bright, sunny day, enjoy an expansive vista and understand how exposure to daylight impacts on our wellbeing, living or working in a glass box may bring its own problems; too hot, too noisy, UV damage to interiors and increased risk from blast damage.
This trend to extend the use glass as an envelope cladding, replacing the traditional brick and concrete finishes, places a much greater demand on the performance and design flexibility of the structural glass and requires an open minded, composite approach to achieving multi-functionality through coatings, insulated units and laminated glass technologies. This is clearly demonstrated where specifications may require varying levels of natural light, thermal insulation, solar control, safety or security performances all combined within the same glass panel.
For some time, applying a foil was the only means of adding any additional performance to glass, however, with the advancements made in composite technology over recent years, liquid composites are now becoming the solution of choice for many seeking to make modern glass buildings comfortable for all. Key to the increasing success of liquid, optically clear, adhesives for lamination is that whilst the interlayer significantly enhances and extends the inherent capabilities of the glass composites, it does so without compromising on its clarity. Not only do they offer benefits to the building occupiers, but there are also additional benefits to be gained in the production process in terms of curing speed, improved production capacity, and structural benefits, where they exhibit high performance with regard to creep, tensile and sheer performances.
The main areas where liquid composites are making a real impact for architects, manufacturers and occupiers are:
Safety Glass which combines strength and robustness with versatility and creativity to provide both internal and external solutions that meet both aesthetic and legislative requirements. This is widely used on balustrades, glass partitions, stair cases and other interior structural elements.
Decorative Glass where the application of a liquid composite can significantly improve the opportunity for decorative enhancement with a much wider range of suitable substrates available for inclusion in the lamination process.
Structural applications for the architectural market are ideal for glass to glass and glass to polycarbonate composites. These are already being used extensively on glass flooring & in interior decoration.
Security glass provides protection from ballistic and manual attack, reducing panel weights and the amount of spall (flakes of material broken off a larger solid body often because of projectile impact or blast). Multi-layer glass to glass or glass to polycarbonate specifications have been developed and successfully installed in prisons, civil buildings, high security installations and specialist vehicles, where weight is also a consideration.
UV protection can be achieved with a specialist colourless liquid composite, designed for applications where the highest reduction of ultra violet light transmission across the full UV light spectrum is required without affecting the quality of naturally transmitted light. By using the actual fabric of the building, in the form of specially protected windows to provide UV protection, museums, art galleries, historic houses or even luxury, private residences are provided with an extra layer of UV protection combined with an inherent safety performance.
Sound reduction is achieved with the application of a cured compliant composite which improves glass to glass acoustic insulation performance by decoupling the resonant surfaces and promoting the dissipation of sound energy. This type of glass is receiving a lot of interest from residential care homes, healthcare facilities and educational establishments as they recognise that whilst the light is desirable, the sound that penetrates their buildings may be detrimental to recovery or study and that they need to provide their clients with protection from the noise of the outside world.
One other benefit of using laminates is that their application adds no discernible additional weight to any of units into which they are incorporated, so there is no knock-on effect in terms of structural capability.
Glass technology is an incredibly exciting place to be now, with the growth of “Smart Façades”. Companies are taking existing thermal, solar and safety performances, incorporating the research and development in BIPV (Building Integrated Photo Voltaics) switchable technologies, coatings, embedment and the marriage of glass with new materials. This is leading to ever more complex composite and IG specifications. The bed rock of this is the clever chemistry used in bonding insulated and laminated glasses together.
It is clear from the discussions taking place around the industry that there is an ever-increasing interest in how new laminates and liquid composites are giving glass hitherto unforeseen, additional performances. Architects are responding to developers who are demanding far more than just an aesthetic shell for their new buildings. Providing UV or manual attack protection, bullet resistance or an improvement in acoustic reduction may just be the starting point for a growing interest in developing ‘function in glass’.
Laminating panels of glass with different performance criteria and adding an additional feature to the interlayer itself all help to make these new specifications possible. There will always be a role for foils but as our expectations of buildings, their performance and the materials from which they are constructed continue to expand then the role of the liquid composite is one that is only going to increase.