Film packaging bags are mostly made with heat sealing methods, but also using bonding methods of manufacturing. According to their geometric shape, basically can be divided into three main categories: pillow-shaped bags, three-sided sealed bags, four-sided sealed bags .
Pillow-shaped bags, also called back-seal bags, bags have back, top and bottom seams, making them have the shape of a pillow, many small food bags commonly used pillow-shaped bags to packaging. Pillow-shaped bag back seam to form a fin-like package, in this structure, the inner layer of film is put together to seal, seams protrude from the back of the bag being encapsulated. Another form of closure on the overlapping closure, where the inner layer on one side is bonded to the outer layer on the other side to form a flat closure.
The finned seal is widely used because it is stronger and can be used as long as the inner layer of the packaging material is heat sealed. For example, the most common laminated film bags have a PE inner layer and a laminated base material outer layer. And overlap-shaped closure is relatively less strong, and requires the inner and outer layers of the bag are heat-sealing materials, so not a lot of use, but from the material can save a little.
For example: non-composite pure PE bags can be used in this packaging method. Top seal and bottom seal is the inner layer of the bag material bonded together.
Three-sided sealed bags
Three-sided sealing bag, i.e. the bag has two side seams and a top edge seam. The bottom edge of the bag is formed by folding the film horizontally, and all closures are made by bonding the inner material of the film. Such bags may or may not have folded edges.
When there is a folded edge, they can stand upright on the shelf. A variation of the three-sided sealing bag is to take the bottom edge, originally formed by folding, and achieve it by gluing, so that it becomes a four-sided sealing bag.
Four-sided sealed bags
Four-sided sealing bags, usually made of two materials with top, sides and bottom edge closure. In contrast to the previously mentioned bags, it is possible to make a four-sided sealing bag with front edge bonding from two different plastic resin materials, if they can be bonded to each other. Four-sided sealing bags can be made in various shapes, such as heart-shaped or oval.
Post time: Feb-10-2023