Part 1: Extrusion, Weaving, Coating
Bulk bags are crucial for transportation, but how are they crafted to be so robust? Here’s a breakdown of how FIBC fabrics and bulk bags are made.
What is FIBC fabric? FIBC fabrics, primarily made from polypropylene, are coated with a synthetic film of polypropylene and polyethylene. These fabrics are designed to be strong and versatile, ideal for transporting dry and flowable products.
How is FIBC fabric made? FIBC fabrics are created through the following process:
- Extrusion
- Weaving
- Coating (Lamination)
Extrusion In the extrusion process, raw materials are melted into tapes of specific measurements. The ingredients include polypropylene granules, a small amount of calcium carbonate, a UV stabilizer, and colored pigments if needed. These tapes are then loaded onto bobbins for weaving.
FIBC Fabrics typically consist of:
- Polypropylene 94.33%
- Calcium 3.77%
- UV treatment 2%
Weaving During weaving, the polypropylene tapes from the extrusion process are loaded onto looms. The fabric that forms the bulk bag’s body is woven into shape with warp (vertical tapes) and weft (horizontal tapes) generally at 10-warp x 10-weft tapes per square inch. This fabric has small gaps, making it breathable, which is excellent for some materials but not suitable for others.
Coating (Lamination) For certain applications, the fabric is treated with a laminate coating. In this process, the fabric passes through a thin liquid film of PP & LDPE material, then solidified by chilled rollers. This coating seals the weave’s voids, enhancing the fabric’s physical properties, making it suitable for transporting fine or flowable products and protecting them from moisture.
The lamination material typically consists of:
- PP 350 FG 75%
- LD 1070 LA17 25% (No filler used in the lamination process)
After coating, if applicable, the woven fabric is wound onto large spools and stored until it enters the cutting process, marking the start of Phase 2 of production.