Print stickers can be two types: cast and calendered. These two terms simply describe the processes in which print stickers are made.
1. Calendered
The manufacturing process of calendered can be described as something similar to kneading a dough. The film for this type of is made from similar ingredients to these used in the cast 's film.
PVC powder, liquid softener, stabilizers, colors, resins are mixed into a fine powder mixture called "melt", which goes through an extruder where it's blend into a uniform mass. Adhesive is also add to the liquid mixture which can increase the film's thickness with 1 to 2 mm. Next, the series of large calendering rolls in the extruder, which are heated up to 350 °F, rotate and flatten out this paste into a 2.0 to 4.00 mm thick strip whose length can reach 90 feet depending on the customers' specifications.
● The calendering process
The calendering process includes heat and constant pressure and stress put on the strip, that is stretched and then pressed into its final form. After that, the film goes to an embossing station, where different patterns and gloss effects are added. To get a high gloss, film different embossing tools and calendar line settings are used, for each surface. After this process, the calendered film is cooled down and transported to a winder.
Because the end result is a stiff and thick flim, which is not pliant enough to be applied on a variety of complex surfaces, calendered is suitable for short-term advertising campaigns. Its advantage, over the cast , is that it costs less and is usually printed in large batches. It's resistant to scratches and more easy to handle due to its heavy weight. This makes the print stickers more easy for replacement.
● Calendered Durability
Calendered can last from 1 to 7 years depending on whether it's made from monomeric or polymeric plasticizer. The quality of the plasticizer has a key role to the performance of the material. It's suitable for short-term or medium-term display, such as window and floor graphics, partial wraps and especially point of purchase. So, it may not be a good option for vehicle wrapping. This is because we need a durable material with high resistance to UV rays and the elements. This type also has a limited color palette to choose from.
Contrary to the belief that the thickness of the calendered adds more resistance, its life is shorter than this of the cast print stickers. It's not protected against heat and cold exposure, because tends to shrink to its original size.
When the correct adhesive is added, calendered can be printed with a variety of colors and gloss levels to meet the needs of almost any outdoor application.
2.Cast
We can describe the process of casting as something similar to baking a cake. The used for cast print stickers is made by preparing a mixture of different liquid ingredients (PVC resin, pigment, plasticizer, UV-absorber, fillers, heat stabilizers). They are added to a bowl in a specific order and then mixed together for a specific amount of time and with a particular speed to result in a stable mixture.
A thin film of this mixture, which is called "organosol", is poured on a casting sheet, which sets the texture of the film. Then it goes through ovens which bake it in order to evaporate the solvents. A hard film should form which is then wound in large rollers for further adhesive coating.
This printing process offers a stable and flexible film with surface gloss. This holds well the colors and adheres smoothly to a variety of surfaces, because there is no pressure and stress. Since cast print stickers are thin, they can last really long time (5 to 12 years). You can also apply them on all types of uneven surfaces like curves and corrugations. print stickers are perfect for outdoor display use.