At this time, embryonic tape is used as the raw material of base fabric or loop ( belt ) and it is supplied as raw material. Some enterprises may produce this part of raw material indepently and provide it to the corresponding small and medium-scale FIBC big bag manufacturers; Based on large and medium-scale enterprises with plant management and operation level, the raw materials of base fabric and belt( loop ) can be produced by themselves. For FIBC big bag manufacturers with self-prodcution, the quality of the tape produced in the extrusion line process will affect the quality or tensile strength of the fibc big bag base fabric and loop ( belt ) produced in the next process of circular loom or needle loom.
On the premise that the base fabric or loop (belt, sling) is formed into a rolled product, several processes are mainly including: tape stretching, circular loom, FIBC big bag needle loom process.
Under the certain temperature, the resin is formed into a glass state, which is finally extruded by T die, after extrusion, the embryo film is cooled and shaped by cold water, then after the embryonic flat film is lifted by lifting device and shredded, it is shapped by a hot water tank ( or a hot oven ) at a certain temperature as based on the specific requirements for embryonic tape, which the required tape ( raffia ) specifications are stretched and heated by the first stretching roller device. In order to prevent the formed embryonic tape from shrinking, it can be shaped by the second stretching and heating of stretching roller device, finally, the tape is collected by the tape winder, in which the quality of the tape spindle will also affect the use of warp and weft yarns in the next circular loom or FIBC big bag belt( loop ) weaving link.
The main work flow is that polypropylene masterbatch enters the extruder for heating through batching, mixing and feeding devices in turn.
Particularly, for the tape extrusion plant, the selection factors of one or more tape stretching lines should be considered: First of all, it is necessary to consider the square area of the plant and whether there are suitable supporting facilities to assist the operation of the machine in the plant, which can ensure the continuous operation of the machine and reduce the occurrence of faults. The secondly, it is necessary to configure one or more sets according to the purchasing or export demand.
Combined with the next weaving fabric and weaving belt, these two processes will involve the interweaving process of warp and weft yarns in the operation project, thus forming the FIBC big bag fabric and belt ( loop ) with required specifications, as well as the basic indexes of different tensile strength meeting the requirements of various countries or organizations. Therefore, in multifilament extrusion process, the tape stretching line can be equipped with single / double dies device( including standard wide die ( warp yarns with large width and small thickness) , narrow die ( weft yarns with small width and large thickness) to produce warp yarns and weft yarns with different specifications. Usually, the final output of multifilament extrusion line is related to extrusion and melting.
In the extruder system, the core structure that affects the extrusion capacity lies screw and dies, the screw ( also name as material rod ) mainly includes the feeding zone, melting zone, melting-pumping zone through which the raw materials are heated, compressed and mixed evenly to finally reach the melting amount. The tape stretching line adopts single or double T dies, which mainly includes three parts: screw barrel, die lip and die opening and changes the rotating molten plastic fluid into a parallel linear fluid motion. It is beneficial to ensure the quality of flat multifilament by filtering impurities in materials and preventing plasticized materials from being extruded through the filter screen device.