Sewn Open Mouth PP Bags — A Systems Guide for Modern Packaging

What Are Sewn Open Mouth PP Bags?

Sewn Open Mouth (SOM) PP bags are pre‑made sacks fabricated from woven polypropylene (PP) fabric whose bottom is factory‑closed while the top remains open for filling and is then closed by stitching. In the trade, you will also see aliases such as sewn open mouth woven sacks, SOM polypropylene sacks, PP woven open‑mouth bags, and raffia sewn sacks. At their core, these bags exploit the high tensile‑to‑weight ratio of oriented PP flat tapes woven into a textile that can be sewn quickly and securely.

Key features. High tear and burst resistance along warp and weft; good impact tolerance; stable dimensions under load; compatibility with crepe or woven PP over‑tapes; optional inner liners for hygiene and moisture control; printable surfaces (flexo on coated fabric, or BOPP lamination for premium graphics); suitability for automated filling and sewing heads.

Manufacturing process in short. PP resin pellets → tape extrusion and stretching (orientation) → weaving (circular or flat looms) → optional extrusion coating or BOPP lamination → printing → cutting, gusseting, mouth preparation (heat‑cut or hem) → filling on an open‑mouth line → closure by plain sew or tape‑over‑sew → inspection and palletization.

Typical applications. Dry bulk goods in 5–50 kg formats: grains and rice, flour and sugar, animal feed, fertilizers, salt, resins and pellets, industrial minerals, sand and flood control. Where lines need a forgiving, fast, and economical closure, sewn open mouth PP bags are the default workhorse.

How the SOM Architecture Works (and Why It Endures)

Open‑mouth means easy presentation to the filler; sewing means rapid mechanical closure unaffected by small variances in fill height or mouth alignment. The folded mouth (commonly 20–35 mm) spreads stress and tames fray; a 2‑thread chain stitch creates a tough seam. Add a crepe or woven PP tape over the fold and you bridge needle perforations, suppressing powder sifting and improving cosmetics.

Problem → solution → result.

• Fray and edge tear → Fold the mouth and stitch through the hem → Higher seam tear‑out strength, better handling.
• Powder sifting through needle holes → Apply PE/crepe/woven‑PP over‑tape and sew through → Reduced dust emission, cleaner pallets.
• Moisture risk → Integrate an inner LDPE/LLDPE liner (≈50 ±10 μm) and heat‑seal liner before external sewing → Improved barrier without losing open‑mouth flexibility.

Where SOM Shines Compared With Other Closures

Contrasted with glued paper closures or welded block‑bottom sacks, SOM PP bags offer low unit cost, broad material compatibility (coated or uncoated fabric, laminated or plain), and high tolerance to fill‑height variability. They are especially attractive for medium‑to‑high‑throughput lines that mix SKUs (feed, grains, fertilizers) and need quick changeovers with robust performance.

Comparative study.

• Versus glued/pasted paper OM bags: SOM PP is more tolerant to dust and humidity in the sewing area, with higher tear resistance. Paper wins on print crispness and drop‑in recyclability where paper streams dominate.
• Versus welded block‑bottom PP sacks: Welded sacks are superior for leak‑tightness and cube efficiency, but SOM demands less CAPEX and accepts wider fill‑height/width tolerances.
• Versus pinch‑bottom paper or hot‑melt OM: SOM avoids adhesive set‑time constraints and fares better on abrasive products.

System Map — Decomposing the SOM PP Bag

A SOM PP bag is a system with four interacting sub‑systems. Design by sub‑system, validate by interface.

1. Fabric system. Tape denier, mesh (e.g., 9×9 to 12×12), and GSM (50–120 g/m²) govern tensile, creep, and puncture resistance. Coating (~17–30 g/m²) improves moisture barrier and weldability (for hybrid lines), while uncoated fabric breathes for grains.
2. Barrier system. Optional inner liner (≈50 μm LDPE/LLDPE), micro‑perforation level, and surface treatments (anti‑slip, anti‑static, UV 200–1600 h) modulate shelf‑life and handling.
3. Closure system. Plain sew (2.5–4 stitches/cm) for granules and pellets; tape‑over‑sew with 50–70 mm tape for fine powders; hybrid inner heat‑seal + outer sew where hygiene or odor control is critical.
4. Interface system. Mouth width vs. filler spout OD, bag length vs. net‑weigh target, conveyor speed vs. sewing head rpm (e.g., high‑speed heads up to ~2,700 rpm), tape feed and cut consistency, drop‑test criteria.

Integration rule. Change one sub‑system only after acknowledging the effect on the others: heavier coating may demand sharper needles and higher foot pressure; denser mesh may reduce sewability if stitch density is not adjusted.

Data Reinforcement — Typical, Real‑World Ranges

The ranges below mirror current supplier catalogs and trade listings for SOM PP bags (25–50 kg):

• Dimensions (length × width): ~300–1200 mm × ~300–750 mm (tubular body), custom on request.
• Fabric mesh: 8×8 to 12×12 for common duties; up to 16×16 for premium light‑duty graphics.
• GSM: ~40–140 g/m² (40–60 for light agri sacks; 60–90 for grains/feed; 65–80 for cement markets in some regions).
• Mouth preparation: heat‑cut, cold‑cut, or hemmed; typical fold 20–35 mm.
• Stitch density: ≈2.5–4 stitches/cm (chain stitch); needle size matched to fabric/liner stack.
• Over‑tape width: 50–70 mm (crepe, PE, or woven PP tape) where dust control is required.
• Line behavior: automated open‑mouth lines routinely place and sew bags at effective conveyor speeds in the ~16–23 m/min band, while modern sewing heads reach up to ~2,700 rpm.

Use‑Case Matrix — Which Products Prefer SOM PP?

Product / Risk profile	Recommended SOM setup	Rationale
Rice, grains (condensation risk)	Uncoated fabric; micro‑perforated; plain sew or tape‑over‑sew	Breathability limits condensation; tape suppresses dusting at conveyors
Flour, fine minerals	Coated fabric; tape‑over‑sew; optional inner liner	Bridges needle holes to reduce sifting; coating aids hygiene
Animal feed (pellets)	Un/Coated fabric; plain sew	Low sifting risk; economical, fast
Fertilizers (hygroscopic)	Coated fabric + liner heat‑seal + outer sew	Controls moisture ingress; robust outer seam
Resins/pellets	Coated or BOPP‑laminated; plain or tape‑over‑sew	Smooth pellets; line speed priority
Salt	Coated + liner optional; tape‑over‑sew	Moisture protection; reduced spill on transport

Quality, Compliance & Tests — From Fabric to Seam

Standards and references you can cite in specs.

• ISO 23560:2015 — Woven polypropylene sacks — Requirements and test methods (25 kg/50 kg sacks for foodstuffs).
• GB/T 8946‑2013 — General technical requirements of plastic woven sack (PRC national standard; last reviewed 2025).
• GB/T 8947 — Plastic woven cloth (substrate fabric).
• FDA 21 CFR 177.1520 — Olefin polymers for food contact (PP resin compliance, where applicable).
• ASTM D5276‑19 — Drop test of loaded containers by free‑fall (bags and sacks ≤50 kg).
• ISO 13935‑2 — Seam tensile properties of fabrics — Grab method (useful for stitched seam evaluation on woven PP).

In‑plant validation plan.

• Fabric & coating: GSM, denier, mesh verification; coating weight gravimetry; tensile (grab) per lot.
• Sewing seam: stitch density checks, needle temperature monitoring in long runs, seam tear‑out strength sampling each hour.
• Dust & hygiene: vibratory “shake” trials on filled sacks; visual dusting index; liner seal‑peel tests when hybrid closure is used.
• Distribution: drop tests at 0.8–1.2 m in multiple orientations; pallet vibration simulation; UV aging where outdoor storage is likely.

Case Files — Three Field Scenarios, One Engineering Method

Case A: 25 kg wheat flour (fine, dusty)

Problem. Stitch perforations allow flour to sift during conveyor transfers; pallet housekeeping costs surge.

Solution. Coated fabric; 60–70 mm woven PP over‑tape; 3.0–3.5 stitches/cm; hot‑knife mouth trim; anti‑slip treatment. If hygiene demands, add 50 μm liner and heat‑seal prior to sewing.

Result. Dust escapes drop visibly in shake tests; pallet bases remain cleaner; claims fall. Throughput remains essentially unchanged because the sewing head speed is maintained.

Data reinforcement. Tape‑over‑sew pedestals are commonly run at effective line speeds on the order of ~17–23 m/min; modern sewing heads operate up to ~2,700 rpm.

Comparative note. A welded block‑bottom sack could reduce dust further but at higher conversion cost and with filler changes.

Case B: 40 kg compound fertilizer (hygroscopic, caking risk)

Problem. Seasonal humidity wicks moisture through the mouth fold.

Solution. Coated woven PP; 50 μm LLDPE liner with bar seal; over‑taped outer sew; add anti‑wick top trim.

Result. Caking is reduced at warehouse exit; flow at discharge improves; complaint rates drop.

Contrast. A paper multi‑wall OM bag with poly liner glues well but is less tolerant to abrasion in rough handling compared to SOM PP.

Case C: 50 lb resin pellets (low dust, high speed)

Problem. Occasional edge tears at the mouth during pallet stretch‑wrapping.

Solution. Increase fold to 30–35 mm; move needle line at least 10 mm from edge after trim; use polyester thread; plain sew.

Result. Seam tear‑out improves; no measurable speed loss; wraps cleanly on the palletizer.

Historical Trajectory — From Textile Logics to Polyolefin Engineering

Origins. The SOM PP bag blends two 20th‑century revolutions: modern textile engineering (looms, seam science) and the polyolefin breakthrough of the 1950s, when isotactic polypropylene was unlocked by Ziegler–Natta catalysis. Once propylene could be polymerized into a crystalline, strong, and processable plastic, it was inevitable that woven “raffia” tapes would replace heavier jute or cotton sacks for many duties.

Early adoption (1960s–1980s). Tape extrusion + weaving produced robust fabrics; sewing gave a familiar, low‑cost closure. Agriculture and construction led adoption because they demanded strength and weather tolerance.

Application expansion (1990s–2010s). As coating and BOPP lamination matured, SOM PP diversified into branded consumer‑adjacent categories (pet food, rice) while retaining industrial niches (minerals, salts). The product family fragmented into finer sub‑types: micro‑vented uncoated for grains; coated and tape‑over‑sew for powders; hybrid liner‑seal + sew for hygroscopic goods.

The China story. In China, SOM and related PP woven packaging scaled dramatically through private entrepreneurial clusters. Wenzhou’s Pingyang County (Xiaojiang Town) is widely recognized as a plastic woven hub—often dubbed the “China Plastic Woven Capital”—with industry chronicles tracing growth from the late 1970s to a large, export‑oriented cluster by the late 1990s. Over time, the cluster broadened from simple sacks to a full ecosystem: raw materials, weaving/lamination machinery, pre‑press and printing, logistics, and brand services. The current challenge—and opportunity—is to couple that manufacturing scale with sustainability, brand building, and rigorous quality management as domestic and export markets segment into ever more specific niches.

China: Strategy to Strength — What Manufacturers Must Emphasize Now

Sustainability. SOM PP can be specified as a mono‑material package: PP fabric + PP coating + PP over‑tape + PP thread to streamline recycling. Plants should audit resin choices against food‑contact regulations where needed and consider recycled‑content PP grades (where allowed) for industrial SKUs.

Brand & graphics. For retail‑adjacent SKUs, BOPP‑laminated SOM PP enables photo‑grade graphics and scuff‑resistant surfaces while preserving sewability. Register‑control in flexo printing on coated fabric is the pragmatic cost/performance midpoint for commodity goods.

Quality doctrine. Codify process windows: stitch density per fabric GSM; allowable needle size ranges; liner seal parameters (temperature/dwell/pressure); drop‑test heights by SKU; UV programs for outdoor storage SKUs. Certification anchors such as ISO 9001:2015 and FSSC 22000 (Packaging Manufacturing scope) are increasingly required by international buyers.

Market segmentation. Build SKUs around risk profiles—“low‑dust plain sew,” “powder‑grade tape‑over‑sew,” “liner‑seal hygiene grade”—instead of generic “one bag fits all.” This aligns production with customer value and prevents over‑ or under‑engineering.

Spec Table — Typical Parameters for Sewn Open Mouth PP Bags (25–50 kg)

Values reflect real trade specifications; tune to product risk and line capability.

Item	Typical Range / Option	Notes
Capacity	5–50 kg (10/20/25/40/50 kg common)	Custom sizes on request
Length × Width	~300–1200 mm × ~300–750 mm	Tubular body; gussets optional
Fabric GSM	~40–140 g/m²	60–90 g/m² common for grains/feed
Mesh	8×8 to 12×12 (to 16×16 premium)	Warp × weft
Coating	~17–30 g/m² PP/PE	Moisture barrier & sewability
BOPP lamination	10–21 μm	Graphics & stiffness
Liner	50 ±10 μm LDPE/LLDPE	Heat‑seal in hybrid closure
Mouth fold	20–35 mm	Boost seam tear‑out
Stitch density	~2.5–4 stitches/cm	Chain stitch, 2‑thread
Over‑tape width	50–70 mm	Crepe/PE/woven PP
Sewing head speed	Up to ~2,700 rpm	High‑speed DS‑class heads
Drop test	0.8–1.2 m, multi‑orientation	Per ASTM/ISO methods

From Questions to Architecture — A Practical Selection Workflow

1. What failure will you not tolerate? Dust escape? Moisture ingress? Edge tears? Choose plain sew, tape‑over‑sew, or hybrid liner‑seal + sew accordingly.
2. What does the product demand? Particle size, hygroscopicity, odor sensitivity define liner and coating decisions.
3. How does the line behave? Filler type (gravity, auger, net‑weigh), conveyor speed, and mouth presentation decide mouth fold and stitch density.
4. Where will the bag live? Depot humidity, outdoor storage, stack height inform coating weight, UV program, and anti‑slip selection.
5. What must the bag say? Commodity flexo vs. BOPP graphics; ink set compatible with food or feed as applicable.

Deliverables from this workflow: a one‑page spec with fabric/mesh/GSM, coating/lamination, liner gauge (if any), mouth fold and stitch density, over‑tape width (if used), validations (drop, seam, dust), and certification statements (ISO/GB/T/FDA clauses).

Horizontal vs. Vertical Reasoning — Making the Choices Stick

Horizontal (cross‑domain). Borrow seam logic from apparel and technical textiles; apply barrier thinking from film packaging; adopt OEE insights from material‑handling engineering. The result is a SOM PP bag that flows through the plant and survives the field.

Vertical (layered). Move from polymer to tape to fabric to seam to pallet. At each layer, define the risk, the control, and the check. Example: polymer MFI → tape draw ratio → fabric GSM → seam stitch density → drop‑test height.

Future Trends — Automation, Data, and Circularity

• Automation. Automatic bag presentation and transfer on open‑mouth lines will continue to expand. Expect sensorized sewing heads that log rpm, temperature, and stitch density, with alerts when drifts exceed setpoints.
• Data. Digital batch records for liner seals and seam checks will become routine as buyers demand traceability.
• Circular design. PP‑only builds (fabric, coating, tape, thread) and inks/adhesives designed for PP recycling streams will differentiate suppliers.

Reference Clauses You Can Paste Into a Specification

• “Woven PP sacks shall meet ISO 23560:2015 relevant performance clauses for 25/50 kg foodstuffs packaging.”
• “Compliance with GB/T 8946‑2013 is required for dimensions, tolerances, seam strength, and visual quality.”
• “Where direct food contact is intended, all resins shall conform to FDA 21 CFR 177.1520 and the site shall maintain FSSC 22000 certification (Packaging Manufacturing scope).”
• “Seam validation shall follow ISO 13935‑2 grab method; distribution robustness shall be proven by ASTM D5276 free‑fall drop testing at 0.8–1.2 m.”

Worked Bill of Materials (Example: 25 kg Flour, Tape‑Over‑Sew)

• Fabric: 70 g/m² woven PP, mesh 10×10, anti‑slip treatment.
• Coating: 20 g/m² PP/PE.
• Liner (optional): 50 μm LLDPE, hot‑bar sealed.
• Mouth: 30 mm fold, 60 mm woven‑PP over‑tape, 3.2 stitches/cm.
• Print: 6‑color flexo on coating.
• QA: Seam sampling every 30 minutes; drop test 0.9 m, five cycles; dust vibratory index ≤ defined site target.

Outcome. Lower dust claims, stable throughput, improved pallet cleanliness.

Worked Bill of Materials (Example: 25 kg Rice, Plain Sew)

• Fabric: 65 g/m² uncoated PP, mesh 10×10, micro‑perforated for breathability.
• Mouth: 25 mm fold, plain chain stitch, 3.0 stitches/cm; needle set matched to fabric denier.
• Print: 4‑color flexo; matte varnish optional.
• QA: Drop test 0.8 m; seam tear‑out > site minimum; condensation checks in seasonal trials.

Outcome. Balanced breathability and robustness with minimal consumables.

A Note on the Wenzhou (Pingyang–Xiaojiang) Cluster

Industry chronicles credit Wenzhou merchants for scaling China’s PP woven bag sector from small workshops in the late 1970s to today’s integrated cluster commonly branded the “China Plastic Woven Capital.” The cluster’s resilience came from fast equipment upgrades, dense supply‑chain networks, and a culture of private entrepreneurship. The next chapter emphasizes sustainability, documented quality, and brand building as markets segment into finer niches and buyers demand traceable, recyclable, and well‑printed SOM PP solutions.

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Prepared for product managers and packaging engineers who need a practical, standards‑anchored overview of Sewn Open Mouth PP bags. Values and examples are indicative; specify to local regulations, customer codes, and line capability.

Introduction — Framing the Packaging Problem

Sewn Open Mouth PP Bags sit at the intersection of strength, speed, and affordability. They look simple; they are not. Behind the plain exterior lies a textile architecture of oriented polypropylene tapes, a closure logic built on stitching physics, and a supply‑chain promise: fill fast, travel far, arrive intact. When a buyer asks for a 5–50 kg solution that works across grains, fertilizers, salts, or resins, Sewn Open Mouth PP Bags answer with pragmatic reliability.

What Are Sewn Open Mouth PP Bags? Definitions, Aliases, and Core Traits

In conversion plants, Sewn Open Mouth PP Bags are fabricated from woven polypropylene (PP) fabric with a factory‑closed bottom and an open mouth that is stitched after filling. The format appears under several aliases—sewn open‑mouth woven sacks, SOM polypropylene sacks, PP woven open‑mouth bags, raffia sewn sacks—yet the mechanics remain the same: present an open bag to the filler, meter product, fold ~20–35 mm, and sew a two‑thread chain stitch. The result is a seam that resists tear‑out and a package that tolerates modest height variation at the mouth.

Features in plain language. High tear and burst strength along warp and weft; resilience against puncture; dimensional stability under stacked load; compatibility with over‑tapes (crepe, PE, or woven PP) to suppress powder sifting; optional LDPE/LLDPE inner liners for hygiene and moisture protection; printability via flexo on coated fabric or via BOPP lamination for retail‑grade graphics. In other words, Sewn Open Mouth PP Bags are forgiving on the line and dependable in the field.

Method — A Systems Way to Specify Sewn Open Mouth PP Bags

Problem first, components second, interfaces last. Break the task into four subsystems: (1) fabric mechanics (denier, mesh, GSM), (2) barrier strategy (coating weight, liner gauge, venting), (3) closure behavior (plain sew vs. tape‑over‑sew vs. hybrid liner‑seal + sew), and (4) equipment interface (filler spout OD, conveyor speed, sewing head rpm). Then ask vertical questions—polymer → tape → fabric → seam → pallet—and horizontal questions—how seam logic from apparel, barrier logic from flexible packaging, and OEE logic from material handling combine inside Sewn Open Mouth PP Bags. The method yields a clean loop: problem → configuration → test → result → adjustment.

Materials and Constructions — What Changes, What Stays the Same

The fabric is a field of tapes. Draw ratio raises tensile; denier and weave (commonly 8×8 to 12×12) set puncture tolerance; GSM (≈40–140 g/m²) balances weight and strength. Coating (~17–30 g/m² PP/PE) adds moisture control and seam consistency; BOPP lamination (10–21 µm) contributes graphics and stiffness for auto‑handling while preserving sewability when needles and fold geometry are tuned. For hygroscopic or odor‑sensitive products, an inner liner ~50 ±10 µm is heat‑sealed inside before the outer mouth is sewn. Micro‑perforation aids grains that respire; anti‑slip emboss or weave patterns stabilize pallets; UV packages (200–1600 h) protect outdoor inventory. These levers, pulled together, shape how Sewn Open Mouth PP Bags behave in the plant and on the road.

Closure Mechanics — The Four Expressive Options Inside One Family

Plain sew (fold‑over stitching). Economical, fast, and robust for granules and pellets; keep the needle line ≥10 mm from the trimmed edge to reduce tear‑out during stretch‑wrap.

Tape‑over‑sew. A 50–70 mm over‑tape bridges needle perforations and compresses the mouth, cutting dust loss on flour, minerals, and salt while improving cosmetics; choose woven‑PP tape to keep a monomaterial build.

Hybrid liner seal + outer sew. Inner thermoplastic seal for airtightness, plus an external stitched/taped seam for mechanical strength—ideal for sugar, detergent powders, and hygroscopic fertilizers.

BOPP‑laminated, sewn mouth. When branding matters, BOPP adds high‑fidelity graphics; tuned needle selection avoids film scuffing at the fold.

One question, many answers: what failure do you refuse to accept—dust, moisture, or mouth tear‑out? Each answer maps to a closure expression of Sewn Open Mouth PP Bags.

Results — Three Problem–Solution–Result Vignettes

Flour (25 kg). Problem: sifting through stitch holes soils pallets. Solution: coated fabric + 60–70 mm woven‑PP over‑tape + ~3.2 stitches/cm + hot‑knife mouth trim. Result: housekeeping time falls; claims drop; speed holds because sewing head rpm is unchanged.

Fertilizer (40 kg). Problem: monsoon humidity wicks into the fold and cakes the product. Solution: coated fabric + 50 µm LLDPE liner heat‑sealed + over‑taped outer sew + anti‑wick top trim. Result: caking decreases; discharge flows; returns decline.

Resin pellets (50 lb). Problem: occasional mouth edge tears during pallet wrap. Solution: increase fold to 30–35 mm, keep needle ≥10 mm from edge, use polyester thread. Result: seam tear‑out improves without sacrificing throughput.

Discussion — Horizontal and Vertical Reasoning in Practice

Why borrow from apparel? Because seam stability and stitch density rules travel well. Why learn from flexible packaging? Because coating weight and sealing windows determine barrier reliability. Why listen to material‑handling engineers? Because conveyor speed, bag presentation, and sewing head rpm set the ceiling for OEE. Cross‑domain thinking helps Sewn Open Mouth PP Bags behave like parts of a single machine, not isolated widgets. Vertically, move from polymer MFI to tape draw ratio to fabric GSM to seam density to drop‑test height; each layer explains the next, and together they explain performance.

Implementation — A Compact Workflow You Can Run This Week

Define the non‑negotiable failure (dust, moisture, or seam strength). Profile the product (particle size, hygroscopicity, odor). Audit the line (spout OD, conveyor speed, space for tape feed). Choose the closure (plain sew / tape‑over‑sew / hybrid). Lock the parameters (fold 20–35 mm, stitch ~2.5–4 stitches/cm, over‑tape 50–70 mm). Prove it (drop tests 0.8–1.2 m; seam tear‑out sampling; dust vibratory trial). Freeze the process window with upper and lower controls, not just targets. That is how Sewn Open Mouth PP Bags become predictable assets, not variable costs.

Specifications Snapshot — Typical, Real‑World Ranges

Parameter	Typical Range / Options	Notes
Capacity	5–50 kg (10/20/25/40/50 kg common)	Custom sizes available
Fabric GSM	~40–140 g/m²	60–90 g/m² common for grains/feed
Mesh	8×8 to 12×12 (to 16×16 premium)	Warp × weft
Coating	~17–30 g/m² PP/PE	Moisture + seam consistency
BOPP film	10–21 µm	Graphics + stiffness
Liner	50 ±10 µm LDPE/LLDPE	Heat‑seal in hybrid closure
Mouth fold	20–35 mm	Improves tear‑out strength
Stitch density	~2.5–4 stitches/cm	Two‑thread chain
Over‑tape width	50–70 mm	Crepe / PE / woven‑PP
UV program	200–1600 h	Outdoor storage SKUs

Use these as guardrails, then calibrate to your filler, climate, and claim history.

Learn More — Formats, Use Cases, Visuals

For representative styles and application notes, see Sewn Open Mouth PP Bags. Use the gallery as a visual checklist while you finalize specifications with your suppliers.

References (Selected, Non‑CNC)

1. ISO 23560:2015 — Packaging — Sacks made from polypropylene woven fabrics — Requirements and test methods.
2. GB/T 8946‑2013 — Plastic woven sacks — General technical requirements.
3. GB/T 8947 — Plastic woven cloth (substrate fabric standard).
4. FDA 21 CFR 177.1520 — Olefin polymers (polypropylene) for food‑contact applications.
5. ASTM D5276‑19 — Standard test method for drop test of loaded containers by free‑fall.
6. Trade catalogs and listings (Made‑in‑China, Alibaba Global) — Typical GSM/mesh/tape/liner ranges for Sewn Open Mouth PP Bags.