A practical reference for buyers specifying woven polypropylene bags — covering base materials, lamination, printing, and closure options with the technical detail you need to order confidently.
Woven polypropylene fabric is produced by extruding virgin or recycled polypropylene resin into flat tape yarn, then weaving that yarn on circular looms into a tubular fabric. The density and weight of the resulting fabric determines its strength and application suitability.
Fabric Weight (GSM). Grams per square metre (GSM) is the primary specification for woven PP fabric. Common ranges:
55–65 GSM: Lightweight applications — onion mesh overlays, light produce bags, low-load applications under 10 kg. Breathable and economical but limited in puncture resistance.
70–85 GSM: Standard weight for most PP woven bag applications: flour, rice, sugar, animal feed, and seed bags in the 25–50 kg range. Good balance of strength, cost, and printability.
90–120 GSM: Heavy-duty bags for construction materials (cement, tile adhesive), mining aggregates, and industrial chemicals. Higher GSM increases puncture resistance and reduces stretch under load.
Tape Yarn Specifications. Yarn denier, tape width, and mesh count (threads per 10 cm) are specified alongside GSM. Tighter weave patterns with narrower tape produce a smoother surface that accepts print and lamination better, while wider tape at lower mesh count produces a more open weave with higher breathability — preferable for products that need ventilation like onions or potatoes.
Virgin vs. Recycled Resin. Virgin PP resin produces more consistent colour (typically natural white or grey), better print acceptance, and more predictable tensile properties. Recycled content resin is available for non-food, non-printed applications where cost reduction and environmental performance are priorities. We source both and can advise on the appropriate choice for your application.
Additive Packages. Standard bags include a base UV stabilizer package. Enhanced options include: high-HALS UV stabilization for outdoor storage, anti-static additives for fine powder packaging, moisture barrier coatings, and anti-slip coatings for improved pallet stability during transport.
Lamination is applied to the woven PP fabric to add moisture barrier performance, improve surface smoothness for printing, or increase puncture resistance. The two primary lamination types are PE (polyethylene) and BOPP (biaxially oriented polypropylene).
PE Inner Lamination. A low-density polyethylene (LDPE) film is heat-laminated to the inner surface of the woven PP fabric. This creates a moisture and vapour barrier that is critical for hygroscopic products — flour, sugar, salt, animal feed, fertilizer, and other materials that absorb moisture and degrade in humid conditions. PE lamination does not significantly affect exterior print quality. Standard PE lamination weight is 18–25 gsm.
BOPP Outer Lamination. A biaxially oriented polypropylene film is laminated to the outer surface of the bag. BOPP lamination provides a high-gloss, smooth printing surface that supports photographic-quality graphics, metallic ink finishes, and fine-detail artwork. It also adds puncture resistance and a degree of moisture protection from the outside. BOPP-laminated bags are the standard for premium retail packaging of flour, rice, and pet food.
PP + PE Double Lamination. Both inner PE and outer BOPP lamination can be applied simultaneously for products that require both moisture barrier performance and premium print quality. Common for consumer-facing food products where shelf appeal and product protection are both critical.
Extrusion Coating vs. Film Lamination. Both methods are available. Extrusion coating bonds molten polymer directly to the fabric for a stronger bond with no delamination risk. Film lamination uses a pre-made film and adhesive — slightly lower bond strength but better clarity and gloss for printing. We specify the appropriate method based on your end-use requirements.
Printing on woven PP bags uses flexographic printing technology — a rotary relief printing process well-suited to flexible packaging substrates. Understanding the capabilities and constraints of flexographic printing helps you design artwork that translates effectively to the final bag.
Colour Count. We offer up to 6-colour flexographic printing. Each colour requires a separate printing plate. For most industrial and agricultural applications, 2–4 colours are sufficient and keep costs lower. Retail-facing products often benefit from 4–6 colours for a premium presentation.
Print Surface Options. Unlaminated woven PP fabric accepts 2–4 colour print but produces a slightly textured finish due to the weave pattern. BOPP-laminated surface accepts up to 6 colours with significantly better colour vibrancy, line definition, and the ability to reproduce photographic imagery.
Print Area. Standard print is single-side. Double-sided printing (both front and back panels) is available and common for products with bilingual labelling requirements or regulatory text that must appear on all sides. Gusset printing is available on request.
Ink Types. Water-based inks are used for food-contact applications and comply with food-contact migration limits. Solvent-based inks provide better adhesion on unlaminated surfaces for non-food applications. UV-cured inks are available for premium finishes on BOPP-laminated surfaces.
Colour Matching. We match PMS (Pantone Matching System) colours as closely as flexographic printing allows. A tolerance of ±Delta E 3 is standard. For brand-critical colours, pre-production colour approval is strongly recommended before plate commitment.
Artwork Requirements. Files should be provided as print-ready PDF or AI files with fonts converted to outlines, minimum 300 DPI at print size, and 3–5 mm bleed on all edges. Our pre-press team will review artwork before plate production and flag any issues.
The closure method affects fill speed, seal integrity, re-openability, and end-user experience. The right closure depends on your filling equipment, product type, and how the bag will be opened and emptied by the end user.
Sewn Open Mouth. The most common closure for woven PP bags. The top of the bag is sewn shut after filling using an industrial bag closing machine. Sewing thread options include polypropylene (standard), polyester (higher strength), and cotton (compostable, available for specific applications). Sewn closure is robust, low-cost, and compatible with virtually all filling equipment. A heat-sealed inner PE liner can be added for moisture-sensitive products.
Heat-Sealed Closure. The top of the bag is folded and heat-sealed without sewing. Common on laminated bags where a clean, flat top seal is preferred. Heat sealing is faster than sewing on automated lines and produces a tamper-evident seal. Not suitable for very heavy loads where seam strength is critical without additional reinforcement.
Valve Top. A paper or woven PP sleeve valve is built into a corner of the bag. Product is filled through the valve, which closes under bag weight after filling — no separate closing equipment required. Ideal for automatic filling lines handling fine powders, cement, flour, and similar materials. Valve bags produce a neat, clean appearance with no exposed top edge.
Pinch Bottom (Block Bottom). A flat, rectangular bottom with folded and glued or sewn construction. Pinch-bottom bags stand upright unsupported, which improves shelf presentation and storage density. Common in retail flour, pet food, and seed packaging.
Draw Cord. A polypropylene or cotton cord woven into a hem at the bag top allows re-closure after opening. Used for packaging that end users access repeatedly — animal feed, seed, and some consumer products.
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