PP woven sacks are manufactured through a multi-step process starting from raw polypropylene resin and ending with finished bags. This involves extrusion, weaving, and finishing stages for durable packaging.
Step-by-Step Process:
PP Resin Extrusion and Tape Formation: Polypropylene pellets are melted at 180-220°C in an extruder, forced through a die to form a thin film, cooled, slit into narrow yarns, and stretched in ovens to create strong flat tapes. These tapes are heat-set and wound onto bobbins.
Circular Weaving: Warp tapes from bobbins feed into a circular loom, where shuttles insert weft tapes in a criss-cross pattern through warping, shedding, weft insertion, and beating-up (using a reed to pack yarns tightly). This produces tubular woven fabric rolls.
Lamination/Coating: The fabric is coated or laminated with a plastic layer for moisture resistance, often using BOPP film, especially for food or chemical packaging.
Printing: Designs, logos, or labels are flexo-printed onto the fabric in multiple colors for branding and information.
Cutting and Sewing: Fabric is cut into panels using hot knives for sealed edges, then folded and stitched (bottom and top gussets) to form sacks, with handles added if needed.
Quality Control and Baling: Bags are inspected for strength, print quality, and defects, then stacked, compressed, and baled for shipping.
Description provided by indian stalwart global sourcing company.