The 8 points comparison between the NovoGlass®SF Film and the PVB
Until now the PolyVinylButyral (PVB) has been the traditional material used to laminate arquitectural glass in autoclaves. Since the seventies a lot of working experiences have been collected to help us know about the disadvantages and problems of using the PVB. The most important ones come from the low adhesion to glass and delimitation problems that normally appear after a wile. But let’s go through the 8th more important reasons.
1.- Is there a way to save storage and handling cost of PVB?
The first problem to set out is the infrastructure required to preserve and store PVB film. On one side, PVB is a material with an extreme tendency to absorb humidity. Since humidity block the PVB adhesive property at glass, it’s necessary and essential to keep PVB protect of relative humidity in “dry” rooms for that. Likewise, from 10ºC PVB is blocked, that is, PVB is stick with itself in irreversible way, so that, also, it’s necessary to keep the PVB film cooled.
PVB must be protected of humidity and temperature to keep intact its property of adhesion at glass. That force to have a cooled space (around 18ºC) to store and assemble the PVB laminated, with a strict humidity control (25%), everything very expensive to support economically. It’s for these reasons that PVB is a product with a short shelf life, and its final properties depend a lot of on storage and handling conditions. In addition, these operational requirements don’t allow to keep a medium period stock, preventing to react with celerity when an unexpected order arrives.
Instead, NovoGlass®SF film isn’t a material with such conservation and handling needs. Obviously, NovoGlass®SF is a material with excellent optical performances which must be cared and protected like a fundamental element for transformer’s production process. Obvious precautions such as protects it from dirt, doesn’t expose it at heat sources, etc. NovoGlass®SF doesn’t require special storage or handling conditions. A maximum temperature of 30ºC and a relative humidity of 60% are adequate to preserve the product. That is, NovoGlass®SF can be stored away from rooms with humidity control and temperature control. In contrast to PVB, NovoGlass®SF can be removed from its original packaging and still be used without any problem until its expiry date, and can be stored away from rooms with thermal control and humidity control. Consequently NovoGlass SF will help you to save manufacturing costs.
While PVB expiry date is 6 months in its original packaging unopen and in strict conditions of humidity and temperature, NovoGlass®SF can be used with full guarantee until one year of manufactured date, independently of NovoGlass®SF original packaging is kept open or close.
2.- I cannot allow to loose glass adhesiveness!
Curiously, PVB is a material with a very low glass adhesiveness, while NovoGlass®SF is manufactured to achieve a glass adhesiveness at least 2-3 times higher. The low PVB adhesiveness and its ability to absorb humidity make that, in glass-glass laminated, humidity penetrate by capillarity between PVB film and glass, forming bubbles and delaminates at the edges of laminated make with PVB. In that sense, almost everybody has some professional delimitation examples to talk about.
In architecture, by design and aesthetic questions, it’s frequent to keep “nude” the edges of laminated glasses, without any protection. It’s in these conditions where glass adhesiveness and mechanical resistance are critical. All of us have seen some time a construction made with glasses laminated with PVB (usually public buildings such as airports, railway stations, etc) where we can observe the typical de-lamination pattern in the edge. The above picture shows a typical example of a floor PVB glass de-lamination.
The high glass adhesiveness of NovoGlass®SF reduce to a minimum the possibility that a glass-glass laminated made with NovoGlass® SF delaminate in the future. Thus, the laminated with NovoGlass®SF can be with “nude” edges without the fear that in a short time the de-lamination start, even in climates with relative humidity levels very high.
3.- About silicones issues or how a fellow passenger can turn into your worst enemy.
Sometimes adhesive materials, sealants and/or filler material are applied on laminated structures. Usually these materials are silicones or other kind of polymer materials. A typical and serious problem of PVB is its bad interaction with silicones and the other materials used for adhesion and/or sealed.
Silicones, even being neutral, contain solvents and other substances which react easily with the most of polymers. The silicones manufacture process is very complex and big differences can be found between the different grades and batches. On the whole, all silicone brands have a professional range, with high performances and more reliable in the repeatability of its composition. However, it’s usual that the silicone, sealant or filler materials are used in the installation to assemble the sides of the glass pieces. Therefore it’s interesting to have an encapsulation material which isn’t affected by the silicone which is used in the installation of the laminated.
PVB is a reactive polymer which is affected by the components (like solvents) contained in silicones, sealant products and/or filler products. As in the case of humidity, this bad reaction causes bubbles and de-laminations in the edges of the piece. In contrast, NovoGlass®SF film is a highly inert polymer which remains stable and unchanged with most of the silicones, sealants and filler products which are applied in the installation of laminated glass pieces.
4.- The fearsome Ultraviolet radiation: with the Sun is beating us!
Solar radiation is composed of ultraviolet radiation (the most energy), visible radiation (or light, which is sensed for human eye), and infrared radiation (which is responsible for heat). UV radiation is a form of high energy capable of ionizing the polymers’ molecules, that is the cause that polymers turn yellow and degrade, losing its mechanical properties.
PVB is a polymer sensitive to the molecular ionization caused by UV radiation, so PVB is additive to protect it of its effects. Is degraded NovoGlass®SF by UV radiation? Yes but in in a much lower amount that PVB, because the NovoGlass®SF molecules require greater energy to ionize. Moreover, the NovoGlass®SF is also additive against UV radiation for, like this, extend still more its life and preserve even more its mechanical properties.
5.- I want to laminate Polycarbonate! What is the best option, PVB or NovoGlass®SF?
One of the most important applications for laminated glasses are anti-theft and/or anti-vandalic security. The target safety level can be achieved by adding internal glass layers at the laminates. However, glass is a very heavy element which increases the weight and the thickness in the final laminated, opposed of the actual trend in architecture with the tendency to lighten the weight of laminates.
So the question is: How to get a laminated structure with antitheft and/or anti-vandalic properties (safety glass) without increasing the weight and the thickness of the laminates? That is possible by replacing the glass interlayers by polycarbonate (PC). But unfortunately the adhesivity of PVB to PC is very poor, while the adhesively of the NovoGlass SF film to PC is extremely good (higher than 110 N/cm). Moreover this great adhesion to PC keeps almost constant under humidity environments, because the extremely good chemical interaction between the PC and the NovoGlass SF material.
The combination of layers of NovoGlass SF with PC improves the mechanical properties and the penetration resistivity of the laminates being closer to the bullet proof security laminates structures.
6.- What else can NovoGlass®SF offer me that PVB cannot give me?
The answer at this question is very easy: mechanical properties.
NovoGlass®SF is a polymer which stands out for a lot of its mechanical properties like hardness, abrasion resistance, tear resistance, penetration resistance, elasticity, etc, but for its application as encapsulation film in laminated glasses we are going to focus in two parameters which appear in data sheet product usually.
The first parameter is tensile strength. This parameter indicates the maximum force which can be applied by tensile (stretching) at the material before its breakup or its distension. That is, as greater is the tensile strength in a material, more rigid and tough will be it. NovoGlass®SF has a tensile strength 1.5 times greater than PVB. Seen this way may not seem a lot, but if we think that we can apply a tensile strength of 10 tons more per square meter of film we can realize the magnitude of what we are talking.
The second parameter is tensile elongation. This parameter indicates how much the material stretch or deform before its breakup. The tensile elongation for NovoGlass®SF is 2.5 times higher than PVB. NovoGlass®SF is capable of increase its size until 950 times before its breakup. The NovoGlass SF has much better elastic properties than the PVB.
So to your question: What benefit get my glass-glass laminated for these parameters? In a laminated the glasses will break before the NovoGlass®SF film. The NovoGlass®SF film capacity to contain anything, and to avoid which go through the broken laminated, is very higher than the PVB capacity. We think in a glass-glass laminated which works as step. Giving a blow the glass of this step can broke but the NovoGlass®SF film will prevent a person who is stepping on from falling to his death.
Using NovoGlass®SF it’s possible to built structures which keep its structural stiffness after tempered glasses are broken while in PVB laminated glass this isn’t possible, because PVB laminated looses all their stiffness, bending and collapsing. Structures laminate with NovoGlass®SF do not collapse and, besides, they have enough capacity for support the weight of a person who is stepping up that step in that moment, and impeding who fall into the void.
Another clear example would be a glass roof laminated with NovoGlass®SF. Even if an object falls down on it and breaks the glasses, the object would be retained by the NovoGlass®SF film structure, avoiding big damages.
7.- Is really more expensive the NOVOGLASS®SF than the PVB film?
The encapsulate film inside of the glass laminated represents a low percentage cost of the total structure, lamination processing, and laminate installation costs.
As it has been pointed out previously, the PVB glass laminates might suffer from bubbles and de-laminations processes. These defects are the cause of clients rejections and business losses. Under these situations, a reasonable question pops up: Does it make sense to save a small quantity of money by choosing a cheaper encapsulant than taking the risk of redoing the job, doubling the materials, manufacturing and installation costs? And the worse payback you might get from these situations, your credibility and brand erosion, if they are not completely loosed.
8.- And what about the processing conditions: What I have to do if I want to laminate with NOVOGLASS®SF? Do I need new equipment?
The answer to the second question is No. There is no need to buy new equipment. You can use the same equipment that you use for PVB. It is possible to laminate glass with NOVOGLASS®SF like PVB, but changing in some way the recipe. In advantage you can get better results reducing processing times and using lower processing conditions.
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