Woven bags and non-woven bags use the same raw material, both are polypropylene. The processes are completely different.
Woven bags start with tape drawing. Polypropylene pellets enter the extruder, melt and come out from the die head as a whole sheet of film, blades cut it into narrow strips. The narrow strips still need to go through a stretching machine, only after stretching is the strength sufficient. Stretching ratios vary between manufacturers-aggressive stretching makes the tape hard, lighter stretching makes it softer. The tape is wound into rolls and goes on circular looms. Circular looms weave one row per revolution, warp and weft alternating, what comes out is a tube. The tubular fabric is cut open into flat fabric, bottom sewn and sealed to make bags.
China woven bag production capacity is concentrated in places like Linyi in Shandong, Xiongxian in Hebei, and Wenzhou in Zhejiang. Equipment relied on imports in early years, now there are more domestically made machines. Small factories use circular looms that cost 30,000 to 50,000 yuan per unit, large factories' complete lines cost millions. Factories making fertilizer bags, feed bags, and flour bags basically all use this approach. Rice bags exported to Africa and the Middle East are also woven bags, 50-kilogram standard packing.
Non-woven fabric production is different. After polypropylene melts, it's not drawn into tape but extruded as fine filaments through spinnerets. Fine filaments fall onto a conveyor belt, randomly laid into a layer. Hot rollers press over it, fibers stick together into sheets. This is called spunbond process. There's also meltblown, with finer filaments, mostly used for mask filter cores. For making bags it's mainly spunbond.
Non-woven fabric production line investment is larger than woven bags. One spunbond line, even domestic, costs over ten million yuan, imported equipment is more expensive. But production capacity is high, once running it puts out dozens of tons of fabric per day. Fabric rolls come out and are sent to the bag-making workshop-cutting, edge folding, sewing, punching handle holes, assembly line operation.
The two types of bags are used in different places.
Woven bags go into industrial packaging and agricultural packaging. Cement plants, fertilizer plants, and grain depots are major clients. Cement bags commonly use laminated woven bags, with a plastic film layer inside for moisture protection. Fertilizer bags are mostly open-mouth, sewn shut at the top. Grain bags require breathability, pure woven bags are suitable, won't suffocate or muffle. Logistics turnover bags also use woven fabric, wear-resistant and durable.
Non-woven bags go to the retail end. Supermarket shopping bags, clothing store tote bags, exhibition gift bags are basically all non-woven. Gram weight ranges from 40 to 120 grams, commonly around 80 grams. Too low gram weight is too thin and can't hold things, too high gram weight increases cost unnecessarily.
Load-bearing capacity differs significantly. Woven bags can hold 50 kilograms of rice steadily, determined by structure. Flat tape crossing in warp and weft forms a grid, each crossing point is a support. Force transfers down from the handle, dispersed across the entire fabric. Non-woven fabric fibers are randomly laid, no clear load-bearing path. Pull one point and the surrounding area deforms with it, places under concentrated force break first. Non-woven bags can hold ten-some pounds of stuff, heavier is risky. If overloaded, the handle position tears first.
Printing effects differ. Non-woven fabric surface is smooth, ink adheres well, silk screen and heat transfer can both be done. Colors are bright, patterns are clear. Brand merchants like to use non-woven for promotional bags, logos print nicely. Woven bag surface has warp and weft texture, ink gets into the gaps, prints come out blurry. To print clearly you need to first laminate a layer of BOPP film to smooth the surface, then print after lamination. Laminated bags cost significantly more, used for rice bags and flour bags that need to go on shelves and face consumers. Ordinary fertilizer bags and cement bags don't care about appearance, just print a few characters directly on the woven fabric and call it done.
For breathability, woven bags have a natural advantage. Warp and weft weaving has gaps, water vapor can pass through. Grain fears suffocation, stored for long periods internal humidity rises and it will mold. Woven bags breathe, grain depots have always used them. Non-woven fabric breathability depends on gram weight and process, thin ones breathe, thick ones not so much. To make breathable non-woven bags you can punch holes, but that's an extra process.
For waterproofing it's reversed. Non-woven fiber gaps are small, splashing water doesn't easily penetrate. Woven bags have large gaps, water leaks right through. To be waterproof you need lamination, adding a PE film inner layer.
Service life differs greatly. Woven bags withstand abuse. Woven bags used for industrial turnover can run dozens of times, can still be patched when torn. Non-woven bags after a few uses the handle part starts fuzzing, after ten-some times the sewn thread starts loosening, then comes tearing. EU defines reusable bag standards as being able to use 50+ times, most non-woven bags don't reach this number.
For recycling and disposal, both are polypropylene, theoretically both can be recycled and pelletized. In actual operation, woven bags have higher recycling rates. Factories, grain depots, logistics companies generate waste bags in concentration, recycling stations coming to collect is convenient. Non-woven bags are dispersed among thousands of households, thrown in trash cans after use, mixed in household garbage, sorting costs are high, the proportion that actually goes back to the furnace is low.
Cost structure differs. Woven bags have high raw material proportion, flat tape is just drawn polypropylene, not much processing value-added. Equipment depreciation and manual sewing account for a portion. Non-woven bags also have raw materials as the bulk, but the bag-making segment has high automation, less labor. Printing processing fees account for a higher proportion than woven bags.
Procurement minimum order quantities differ greatly. Non-woven bags have flexible small orders, two or three thousand pieces can be made, suitable for small merchants and temporary event use. Woven bags have high minimum orders, starting at ten or twenty thousand, suitable for factories' long-term fixed procurement. As for unit price, woven bags are cheaper when quantity is large.
