There are many kinds of stretch film that offer a variety of uses. The varieties of this do address some common problems including the size of the load, the weight of this, and the like. There are also stretch films that you can get that are used to protect the UV rays from getting into the product, reduce the static, which is great for electronics, reduce condensation of the product, and the like.
There are two major types of stretch film, the blown stretch film, and there is the cast stretch film. Here, we’ll talk about these types, and other common ones.
Blown Stretch Film
This is one that’s created through blown extrusion and that process utilizes a vertical sort of die that extrudes out the plastic, melting it to create a tube that’s thin. The air then gets blown directly into the center portion of the tube, forming air bubbles with this.
The amount of this that’s blown does determine the width overall of the film that’s finished. They constantly rotate the film, so the speed of this and how it gets pulled in an upward manner determines the film’s thickness.
While it travels upwards to the nip rollers at the top, this film starts to cool down. Once that bubble is then collapsed onto a tube that’s flat, they then move this to the next set of rollers, and from there, they then are woven to the core, and for larger ones, one side of this sits to create a large width of stretch film.
The advantages of this are that you can use this for higher loads and it has a better stretch capacity. It’s also considered better for the load retention that you need. It’s also better in terms of memory, so it’ll stay in a tight manner for a much longer time period. It’s also resistant to tearing, and it’s great for loads that have edges which are sharp.
This tends to be more expensive though, so the costs of this do tend to be a problem for others. It’s also got a chance that it might not be as clear, due to the crystallization that happens with this.
Cast Stretch Film
This is made with cast extrusion, and in this process, they utilize a die that’s horizontal, and from there, they melt the plastic, force this through that horizontal die, and from there, it then sits flat, and it comes out in a shape that’s flat. The size of this does determine how thick it is.
It then goes through some nip rollers that are chilled, and then, the trim is then made in a way that’s a specified type of width, and this is done after they cool this film. The film then gets pushed over the other chilled rollers, and further cooled. Then, at the end of this, is where the film gets placed, and they get packaged into cases so that they can be shipped.
It’s much cheaper, and it usually costs a lot less. It’s also better for clarity and optics too, since the film gets cooled down faster during cast extrusion, and the crystals are far less here.
They also have better tear resistance too. The biggest disadvantage is that over time, it doesn’t really hold the shape, so it’s bad for load retention. So if you’re going to be using this for a long period of time, you may want to consider using the blown options, rather than cast, so that it keeps the same integrity that it’s had up to this point too.