Plastic woven bags are made of polypropylene (PP) as the main raw material, and are made by extrusion, wire drawing, weaving, knitting and bag making.
Polypropylene is a translucent and semi-crystalline thermoplastic with high strength, good insulation, low water absorption, high thermoforming temperature, low density and high crystallinity. It is the main raw material of woven bags. Modified fillers typically include glass fibers, mineral fillers, thermoplastic rubber, and the like.
Plastic woven bags have a wide range of applications. At present, plastic woven bags are mainly used for agricultural product packaging, cement bag packaging, food packaging, geotechnical engineering, tourism transportation, flood control materials, etc. Woven bags mainly include plastic woven bags (woven bags without film), composite plastic woven bags and various woven fabrics. The production process of plastic woven bags is as follows: weave printing, cutting, and sewing into woven bags.
Depending on the equipment used, it can be cut first and then printed, or printed and then cut. Automatic tailors can continuously complete printing, cutting, sewing and other processes, and can also be made into valve pockets, bottom pockets, etc. For plain woven fabrics, bags can be made by gluing the center seam. The production process of plastic woven bags is to compound or coat woven fabrics, coating materials and paper or film. The resulting tube or piece of cloth can be cut, printed, sewn and made into a common bottom seam bag, or punched, folded, cut, printed and sewn into a cement bag, and the obtained piece of cloth can be Sewing, gluing, printing, cutting and gluing into bottom patch pockets. It can also be welded and rolled to make tarpaulins and geotextiles. Plain cloth can be coated or uncoated to produce tarpaulins, geotextiles, etc. , and cylindrical cloths can also be coated or uncoated to produce tarpaulins or geotextiles, etc.
The technical indicators of the flat wire production process are mainly divided into four categories:
1. Mechanical performance index. Mainly include tensile force, relative tensile force, elongation at break, linear speed, linear density deviation;
2. Physical and chemical modification index. There are mainly blending modification, blending ratio, functional additive addition ratio, and blending ratio of waste and recycled materials;
3. Tolerance dimension index. There are mainly flat wire thickness, flat wire width and so on.
4. Physical rheological index. There are mainly draft ratio, expansion ratio, draft ratio and retraction ratio;
The polyethylene material in the bag lining process is heated, melted, plasticized and extruded stably by the extruder;
Squeeze into cylindrical film through the die head; introduce compressed gas to expand to form tubular bubbles;
Use a cooling air ring to cool and shape, pull the herringbone splint and fold it;
Through traction rollers, drive rollers and winding rollers,
Finally, the cutting and heat sealing process is carried out to complete the production of the inner lining bag, and finally the bag is filled.
Pure polypropylene for flat yarn production cannot meet the requirements, and a certain proportion of high-pressure polyethylene, calcium carbonate and color masterbatch must be added. Adding a small amount of high pressure polyethylene can reduce the viscosity and melting speed of the material flow during extrusion, increase the fluidity, improve the toughness and softness of the flat yarn and woven bag, maintain a certain elongation at break, and improve the low temperature impact of polypropylene. .
The addition of grafted polypropylene can reduce the processing temperature and pressure. Improves material flow and adhesion, and even increases tensile strength. The addition of calcium carbonate can change the defects of transparency and opacity, reduce the harmful static electricity generated by friction during stretching and weaving, increase the ink adhesion of printed trademark patterns, and reduce the natural shrinkage of finished products during storage.
Post time: Oct-20-2022