Color-printed woven packaging bag for flexible crack-resistant wall putty powder with a square bottom and valve opening

I. Product Introduction (Woven Bags)

This product is a square‑bottom valve bag (glue‑seal bottom bag), specially designed for dry powder mortars, putty powders, and other powdered materials. The bag body is constructed from a composite of PP woven fabric and PE film, paired with single‑color gravure printing, making it both economical and practical. The bag surface features the product name “Exterior Wall Flexible Crack‑Resistant Putty Powder / Tile Renovation Putty Powder,” the formulation label “Odorless Formula,” and key selling points: “Healthy,” “Low VOC,” “Eco‑Friendly,” and “Strong Adhesion.”

II. Applicable to (Applicable Scenarios)

Packaging for cement-based dry-mix mortar products: exterior wall putty, tile renovation putty, crack-resistant mortar, adhesives, grouts, and more.

Fully automatic valve‑mouth filling on the building‑materials production line

Warehouse stacking, long-distance transportation, container export

Retail and End-User Displays in the Building Materials Market

III. Applicable Materials (Types of Materials That Can Be Packaged in Bags)

Construction powders: putty powder, cement, gypsum powder, tile adhesive, grout, and waterproof coating powder.

Chemical powders and granules: silicon dioxide, plastic pellets, synthetic resins, carbon black, ultrafine powders

Food powders: wheat flour, starch, citric acid, maltodextrin, pet dry food

Mineral powders: talc powder, heavy calcium carbonate powder, quartz sand, bentonite clay

IV. Core Advantages

Automatic filling with a square-bottom valve: Specifically designed for automated filling lines, the filling nozzle inserts into the valve opening, enabling high-speed metering and labor savings.

Leak-proof and dust‑proof: self‑sealing valve opening + pinhole‑free sealed bottom + PE inner liner lamination, eliminating powder leakage and dust.

Monochrome printing, economy model: 1 ~ Two-color gravure printing, with low plate costs (50 ~ 200 yuan), with a unit price only 30% to 50% of that of the full-color model.

Square‑bottom palletizing stability: After filling, the product forms a brick‑shaped cubic form that can stand upright, enabling neat stacking and preventing collapse.

High Strength and Break Resistance: The PP woven fabric boasts high tensile strength and can safely support a load of 25–50 kg.

Moisture-proof and freshness-preserving: The PE film layer effectively blocks moisture, preventing the product from clumping.

Environmental Compliance: Materials are recyclable, inks are benzene- and ketone-free, and comply with national standards and export requirements.

V. Automatic Filling with Square Bottom and Valve Spout

Valve port configuration: One side of the bag is equipped with a filling valve port (either an upper or lower port), and during filling, the filling nozzle is inserted directly.

Filling equipment: compatible with screw‑type valve‑mouth packaging machines (for powders) or pneumatic filling machines (for powders and granules).

Filling efficiency: Line speed can reach 1,200–1,400 bags per hour.

Automatic sealing: The filling pressure causes the inner flap of the valve to fold and seal itself, eliminating the need for manual sealing or stitching.

Fully automated integration: Can be paired with a robotic arm for automatic bagging and palletizing, enabling a dark‑factory operation.

VI. Leak-Proof and Dust-Proof Design Details

The square-bottom valve bag addresses the common issue of powder leakage by incorporating a multi-layer sealing design:

Self-sealing valve port: After filling, the material pressure presses the inner side of the valve port tightly, creating a natural seal.

PE inner‑membrane lamination: The intermediate PE film is formed via thermal lamination, sealing the woven gaps and preventing fine powder leakage.

Hot-melt adhesive sealing: The bottom features a seamless, pinhole-free seal achieved through hot-melt bonding, offering significantly superior leak-proof performance compared to sewn-bottom bags.

Laminated sealing: The outer laminate further seals the surface pores of the woven fabric.

Optional one-way vent valve: If the product contains gas or requires heat dissipation, a vent valve can be installed to prevent bag swelling while also providing dust protection.

VII. Monochrome Printing – Economy Model

Number of printing colors: 1–2 colors (typically the brand logo, product name, and net content)

Plate‑making costs: A single‑color plate costs approximately RMB 50–200, while a multi‑color plate can exceed RMB 300; bulk orders may qualify for discounts.

Price advantage: Compared with full-color customizations, monochrome models can reduce the unit price by 30% to 50%.

Target customers: Small and medium-sized enterprises with limited budgets, companies in the pilot production phase, and industrial product manufacturers with modest packaging aesthetic requirements.

Customizable content: Can print company name, product name, phone number, QR code, recycling symbol, and more.

8. Stable Stacking on the Bottom Side

Post-filling appearance: The powder naturally forms a rectangular prism (brick-shaped) within the bag, with a flat bottom.

Independence: Can stand independently without leaning against a wall.

Stacking performance: The corners are neatly aligned, with a large contact area between layers, allowing for stacking heights of 8 to 10 tiers without tipping.

Warehousing and Transportation: Space-saving, resistant to slippage and collapse, ideal for container and palletized shipping.

9. Comparison between Square-Bottom Valve Bags and Flat Bags (Open-Top Bags/Sewn-Bottom Bags)

Bottom shape: The square-bottom valve pouch has a flat, square base and is sealed with hot-melt adhesive; the flat pouch features a sewn seam closure with visible thread ends.

Filling method: Square-bottom valve bags are filled with automatic tube insertion at the valve opening, ensuring high efficiency; flat bags are filled through an open mouth, either manually or semi‑automatically, and require bag sealing.

Sealed and dustproof: Square-bottom valve bags are superior (self-sealing valve opening + no pinholes); flat bags are inferior (seam pinholes, powder leakage is common).

Palletizing stability: Square-bottom valve bags perform better, offering self‑standing stability; flat bags are less stable, with round bottoms prone to rolling and tipping over.

Automated adaptation: The fully automatic line for square-bottom valve bags is perfectly compatible; flat bags require manual intervention or equipment modification.

Appearance: The square-bottom valve pouch is neat and attractive, ideal for retail display; the flat pouch is simple and has a stitched seam at the bottom.

Cost: Square-bottom valve bags are slightly more expensive (due to their complex manufacturing process); flat-bottom bags are less costly.

Main applications: Square-bottom valve bags are used for cement, putty, chemical powders, and food powders; flat bags are used for ores, crushed materials, and low-value bulk goods.

X. Material and Craftsmanship

10.1 Structural Composition

Outer layer: Color-printed PP woven fabric (single-color printing)

Middle layer: PE film (moisture barrier, thickness 5–12 μm; can be thickened to 80 μm upon request)

Inner layer: PP woven base fabric (basis weight ≥ 65 g/m²)

Bag Type: Square-bottom valve bag (glue-sealed bottom bag), with the valve opening located at the top or bottom.

10.2 Production Process Flow

Drawing → Weaving → Composite Molding → Gravure Printing → Valve Mouth Forming → Glue‑Bottom Bag Making → Hot‑Melt Adhesive Bottom Sealing → Finished‑Product Inspection → Packaging

10.3 Key Parameters

Elongation ratio: 5.0–5.4

Knitting density: Designed according to strength requirements.

Composite fastness: ≥3 N/30mm

Bottom seal strength: Hot-melt adhesive bonding, no pinholes.

XI. Tensile Strength

Longitudinal tensile strength: ≥450 N/50 mm (test standard GB/T 1040.3)

Longitudinal tensile strength: ≥450 N/50 mm (test standard GB/T 1040.3)

Elongation at break: 15%–30%

Peel strength (composite layer): ≥3.0 N/15 mm (test standard GB/T 8808)

Puncture resistance: ≥50 N (cone‑type puncture tester)

Safe load capacity: 25–50 kg (stacking test)

Note: The tensile strength of high-performance woven bags can reach 800 N/50 mm or higher. The above values comply with the GB/T 8946-2013 standard.

XII. Moisture-Proof Rating

Moisture‑proof structure: The intermediate PE film layer forms a dense barrier through thermal lamination.

Water vapor transmission rate: ≤15 g/(m²·24h) (according to GB/T 1037, at 38°C and 90% RH)

Moisture‑proof performance: Under relative humidity conditions of ≤80%, the powder remains free from moisture absorption and caking for up to 3 months.

Upgrade option: The PE film can be thickened to 80 μm or more, reducing the water vapor transmission rate to ≤5 g/(m²·24h).

13. Packaging Drop Test

Test standard: GB/T 4857.5

Drop height: 1.2 meters

Drop sequence: facade → plan → side (tested with three sample bags, respectively)

Acceptance criteria: The bag shall be free of tears, and the contents shall not have spilled or leaked.

Net weight: 25 kg (fully loaded)

XIV. Applicable Filling Method

Filling Equipment: Valve‑port‑specific packaging machines (screw‑type, pneumatic‑conveying, impeller‑type)

Filling process: automatic bag feeding → valve‑mouth docking → automatic metered filling → valve‑mouth self‑sealing → conveyor discharge

Filling speed: up to 300 per machine. ~ 600 bags/hour; the fully automatic line can reach 1,200. ~ 1,400 bags/hour

Auxiliary equipment: Can be equipped with an automatic palletizer and a stretch wrapper to achieve unmanned packaging.

15. Packaging Specifications

Applicable net contents: 15 kg / 20 kg / 25 kg / 30 kg / 40 kg / 50 kg

Common size (25 kg): Width 40 cm × Length 50 cm × Bottom gusset 13 cm (valve bag)

Bag Type: Square-bottom valve bag (with top or bottom valve)

Valve port types: Flanged / Cylindrical / Diaphragm type

Pallet packaging: Typically 200–300 bags per pallet (depending on the specification).

16. Scope of Customization

Printed content: brand logo, product name, instructions, QR code, and recycling symbol (monochrome或多色)

Net content specification: Customizable within any range from 15 to 50 kg.

Bag dimensions: Customized according to material density and customer requirements.

Bag type: top valve mouth/bottom valve mouth, with or without a vent valve

Material: PP, basis weight (45 ~ 80 g/m²), PE film thickness (5 ~ 80 μm)

Moisture-proof rating: Thickened PE film or an additional coating layer

Other features: anti-slip embossing, one-way vent valve, easy-tear notch, and carry handle.

Minimum order quantity: Custom-printed bags typically require a minimum of 10,000 to 30,000 units (single-color prints can be ordered in quantities as low as 10,000).

XVII. Environmental Compliance

Domestic standards: Compliant with GB/T 8946-2013 “General Technical Requirements for Plastic Woven Bags” and GB/T 8947 “Composite Plastic Woven Bags.”

Food Contact: If intended for use with food, it shall comply with GB 4806.7 “National Food Safety Standard for Plastic Materials and Articles in Contact with Food.”

Ink Safety: Benzene- and ketone-free, compliant with GB 9685 “Standards for the Use of Additives in Food Contact Materials and Articles.”

Export Compliance: Meets the EU Regulation (EU) No 10/2011 and the RoHS Directive; can provide certificates of inspection.

Recyclability: Both PP and PE are recyclable materials, meeting the requirements of the circular economy.

18. Price and Minimum Order Quantity

Negotiable

XIX. Applicable Parties (Purchaser)

Dry-mix mortar and putty powder manufacturer (for direct use in product packaging)

Building materials packaging traders and export companies (resell after bulk purchasing)

Brand owners requiring OEM manufacturing (custom private-label packaging)

Cement plants and specialized mortar factories (with automated filling lines)

For small and medium-sized powder-processing enterprises with high packaging costs and stringent automation requirements.