Polyester is used in many areas due to its positive properties – also in our bag production. Whether as felt, matt-melted or shiny single-coloured polyester. Polyester can be used as a base material for almost any look and feel. In the following, we show how versatile this material can be.
Polyester belongs to the family of so-called synthetic fibres or man-made fibres. Unlike cotton or wool, these fibres do not occur naturally and are therefore produced artificially in factories.
The spinneret process is a widespread process in the textile industry that is used to produce synthetic fibres, especially polyester. For this purpose, small polyester granulate (also called polyethylene terephthalate) is melted at high temperature and pressure and pressed through tiny nozzles of a spinneret, similar to a shower head. This creates hair-thin endless threads (filaments), which are then stretched and cooled down so that they retain their shape. The filaments are then collected on a spool and wound up.
By the way: the polyester granulate does not necessarily have to be newly produced from e.g. crude oil, because the granulate required for the production of polyester fibres can also be obtained from recycled PET bottles. Our video shows how a bag is made from a bottle.
Whether a polyester fabric is more matt or more glossy in the end is already decided during the production of the filaments. The melted granulate, as already described above, is pressed through profiled holes in the spinneret head. These holes can be shaped in different ways. You can imagine this, for example, as with piped pastry. Different attachments cause the dough to have different cross-sectional shapes. It is the same with polyester filaments, which get a special surface texture. Later on, this has an influence on gloss, appearance and feel.
In addition, further texturing processes can be used to change the fibre so that the yarn or even the fabric resembles a natural fibre at the end.
In the case of single-coloured fibres, filaments of the same colour are twisted or stretched together. These are the basis for the yarn, which is processed into a fabric. If, on the other hand, two different coloured filaments are twisted together (drawn), the effect of a melange material is created later. Especially when the warp and weft threads (see picture) have the same two colours, the melange appearance is perceived particularly strongly.
Unlike classic polyester materials, felt is not woven during production. For the production of felt, the raw material is first delivered as a fibre block and fed as such into the machine for further processing. This fibre block consists of many short polyester fibres that lie tangled and loose over and under each other. This “pile of fibres” is fed through a machine that “brushes” it step by step into long webs and lays the polyester fibres into an even fibre layer. This layer of fibres is laid on top of each other layer by layer and pressed together between two rollers with heat. In this way, the fibres melt slightly and stick together. Small needles with tiny barbs are then pierced through the resulting felt web to further interlock and felt the fibres together. The felt becomes more solid and dense through this production step. In the end, this creates the finished felt fleece/needle felt.
In order to produce particularly smooth felt, the felt webs can be further processed by passing them over a hot roller, for example. In this way, the fibres are further compacted together and smoothed at the same time. By shearing the felt, all protruding fibre ends are removed and a smoother surface is achieved. In this way, a particularly evenly thick felt fleece is obtained.
If you take a look at our standard range, you will quickly notice that we not only offer white bags, but almost all colours of the rainbow. But how does the colour get into or onto the polyester fabric? Already during the production of the polyester filaments, the colour can be determined by adding coloured pigments to the polyester granulate at the beginning of the melting process. This is also referred to as spinneret-dyed yarn. If this is not the case, the subsequent polyester yarn or the finished fabric can be dyed as desired in an immersion bath.
It is not only the almost infinite customisation possibilities that make polyester one of the most versatile materials on the market. At the same time, polyester is also characterised by its durability and robustness. Many material properties can already be imparted to the polyester fibre during production, even before it is further processed into a fabric or a nonwoven. Particularly in the area of functional products, when high demands are made on resilience or when special properties are desired and necessary, fabrics made of synthetic fibres offer clear advantages over natural raw materials. This high degree of individuality makes polyester an exciting material for bag production.
