It is worth to mention that it is really a complicated and difficult job to select and assemble different type of materials to end up with a perfect laminate. Knowing that any laminated structure is the assembly of different type of materials, the possibility of failure of any of the assembled pieces might depend on many factors. Any type of defect in anyone of the materials, or any malfunction, an incorrect laminated processing or any change of the materials properties along the time might end up in a de-lamination issue.
The de-lamination is the most important problem of any laminated structure. Obviously this is because de-lamination breaks the main purpose of the lamination process, that is the conjunction of different materials. Nevertheless, there are other type of failures in the laminates: optical defects like yellowing, haze, image distortions, and contamination defects like gels, particles, spots,... All of them point out that something in the process is not fully under our control, and deserves our attention.
Since all laminates are constituted by different materials, they are positioned, and processed at certain P, T and t conditions, dealing with delaminates is something similar to play with a jigsaw puzzle. In the best case, the solution to the jigsaw puzzle might be a straightforward, but in general they are difficult, and can become a costly nightmare. In these situations, the idea to look for a material and process expert can be a good idea because it might help you to find the real cause of the issue and even how to fix it.
Well, one thing to consider is that it is generally true that things fail from their weakest part. But the fact that they fail from the weakest part doesn’t mean that they are the cause of the failure. As it has been said before, de-lamination causes could be due to single or multiple factors. In many cases the glue, because is soft, is considered the weakest part, and therefore the responsible of the failure.This is a very simple and not a right conclusion.
It is well known that the best soft material for security and bullet proof glass is the TPU. Specifically the TPUs that fulfill the following main properties are the best suited ones:
- Optical: they have to have high Light Transmission: 89 - 92% with haze values: < 0.5% (1 mm thick), and refractive index: 1.49 - 1.5
- Mechanical: Tensile strength: at around 30 - 40 MPa, Elongation at break: 600 - 900%
- Adhesion to Glass or other materials: > 150 N/cm
- UV radiation protection
Besides all of these properties, it is important when processing, to take into account other important factors like the humidity, the temperature, the pressure and the lamination cycle times.
Depending of the properties of the materials and how the processes are carried out, the laminates might have large or short operational life times. Therefore, we are talking about durability and also about the life cost of the product. In other terms, how to get the best one at lower costs, at the time you make happier your customers raising your reputation?.
The UV protection, the humidity level of the materials, and the type and the level of the adhesion between elements are key parameters to end up with the best security and ballistic resistant glass laminates.
If you want more information, please don’t hesitate to contact us.