EVA Film
Custom Manufacturer of EVA Film
Dana Poly is a custom manufacturer of EVA film. EVA film stands for ethylene vinyl acetate and is an important material for solar panel lamination, as well as other industrial applications. If you are interested in EVA film for industrial applications, please reach out to us today.
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When you reach out, we can provide you with further details regarding EVA films and our custom manufacturing capabilities. Other types of film blends we manufacture include construction film, metallocene plastic films, and hexene bags.
What Are EVA Films?
Cross-linkable EVA is the most common encapsulation in the solar industry. The cells are laminated between films of EVA in a vacuum with the help of a lamination machine, which is under compression. This procedure is conducted under temperatures of up to 150°C. However, one of the disadvantages of EVA films is that it is not UV-resistant. Due to this aspect, protective front glass is required for the UV screening during installation. For standard modules that use EVA encapsulation, the backing usually is a layer of PVF film, PET film or metal. Commonly referred to as Tedlar composite.
When applied properly, EVA lowers the seal initiation temperature and melting point of PE film. In low percentages, EVA has been used for decades for enhancing sealing ability for bread bags, ice bags and frozen food packaging. In higher percentages, more or less 20% EVA, it is used for low melt/total batch inclusion bags. In the end, the higher percentage EVA, the lower the melting point whether measured as DSC melting point.
Higher percentage EVA’s are soft and tacky and solar panels require a bonding layer. The resin of choice has emerged as 33% EVA. It is too sticky to make into film and must be made by the case process. EVA has a pungent, apple vinegar odor which can transfer to foods especially dairy products, so it is not ideal for that application. EVA is considered obsolete by many for packaging applications since metallocene offers faster hot tack. However, demand for EVA remains strong for PVC replacement.
Long Term Encapsulation & Protection
Once the EVA sheets have been laminated, the EVA sheets play an important role in preventing humidity and dirt from penetrating the solar panels. Also, the solar cells 'are floating' between the glass and back sheet with the help of the EVA. This ultimately helps to soften shocks and vibrations. Therefore, protecting the solar cells and its circuits. During application, the layers typically go as followed: glass, EVA film, solar cell, EVA film, and Tedlar composite backing.
EVA Films Properties
EVA films offer different properties, such as durability, bonding, and optical properties. Let's take a closer look at these properties for EVA films and what makes this film so popular.
- Durability: Top-quality EVA film is known for its excellent durability. It works great in difficult weather circumstances, such as high temperatures and high humidity. Without faltering in the process.
- Bonding: Under the right circumstances, EVA film will have excellent adhesive bonding to solar glass. However, it does not have great bonding to standard glass. It adheres well to solar glass because it has a rough surface, whereas standard glass does not. Also, EVA film bonds very well to the back sheet. Ensuring safety and security during installation.
- Optical: EVA film is known for its excellent transparency. This means that the optical transmission is acceptable and does not block too much of the sunshine trying to reach the solar cells. Nowadays, manufacturers may use a transparent backing, which has transparency between the cells as a result. This type of module is known as semi-transparent.
EVA Film Vs PEVA
In a nutshell, EVA and PEVA are the same thing. EVA is short for "ethylene vinyl acetate," which was established already. Somehow along the line, “polyethylene” got added as a prefix. This created the acronym PEVA. At the end of the day, both are words for the same copolymer. Since they are the same material, the terms PEVA and EVA are used loosely. Thus, the end result is confusion for the consumer thinking there is actually a difference.