The Valve Cement Paper Bag is a multi-wall extensible kraft paper sack with a block bottom and integrated filling valve, specially engineered for automatic packing of cement, Portland cement, dry mortar, gypsum, putty powder, and other abrasive fine powders. It is manufactured from high-strength sack kraft pulp, with optional PE coating / PE inner liner for moisture barrier. The valve structure enables air-release filling and self-closing after filling, which is the core difference from open-mouth paper sacks. It is widely adopted by cement plants, mortar factories, and bulk powder distributors for bulk packing, palletization, sea & land transportation, and warehouse storage.
Performance Stability Description
Consistent sack performance is critical for continuous cement production, and we control stability from raw materials, converting process, and finished testing:
• Strength consistency: We use extensible sack kraft paper with stable TEA (Tensile Energy Absorption). The paper absorbs impact energy during drop, stacking, and vibration transit. Every production batch is sampled for burst strength and MD/CD tensile strength to avoid batch-to-batch fluctuation that causes bag rupture.
• Seam & valve bonding stability: Block bottom and valve pocket use high-tack water-based industrial adhesive with controlled gluing pressure and curing time. Bonding strength remains stable under normal temperature and humidity.
• Moisture stability (optional barrier grade): For humid coastal storage or long sea shipment, PE-coated paper or separate PE liner reduces water vapour transmission. It slows cement hydration and caking risk, while the paper maintains its breathability required for air release during filling.
• Anti-abrasion stability: Multi-ply structure disperses friction from sharp cement particles. Under standard drop test (1.2 m drop, full load), qualified sacks remain intact without pinhole leakage.
• Dimensional stability: Strict tolerance control on sack width, length, gusset, and valve opening size.
• Storage stability of empty sacks: Properly packed empty sacks retain physical properties for 6 months under dry warehouse conditions; UV treatment is optional for outdoor temporary stock.
Technical Parameters Table
| Item | Standard Specification | Remarks |
|---|---|---|
| Product Name | Multi-wall Valve Cement Paper Bag | Block bottom valve sack |
| Raw Material | Extensible kraft sack paper (virgin wood pulp/recyclable) | Natural brown kraft paper |
| Paper Plies | 2 / 3 / 4 plies | 3-ply is the mainstream for 50kg cement |
| Base Paper GSM | 70–95 gsm per ply | Adjustable for load requirements |
| Barrier Option | Non-coated / PE coated (10–15 μm) / separate PE liner | PE liner for moisture-sensitive cement |
| Valve Type | Internal valve (standard) / External valve | Internal valve preferred for cement plant |
| Bottom Type | Pasted block bottom (square bottom) | Self-supporting after filling |
| Printing | Flexo printing / Gravure printing | Custom logo, brand, standard marks, barcode |
| Dimension Tolerance | ± 5 mm for length/width/gusset | Custom size available |
| Burst Strength | ≥ 850 kPa | Batch tested |
| Tensile Strength | MD ≥7.5 kN/m; CD ≥5.2 kN/m | Machine direction / Cross direction |
| Drop Test Performance | 1.2 m free fall, full load, no rupture/leakage | Passed for standard grade |
| Stacking Load | Static stacking ≥ 1.8 m height (palletized) | Depends on storage conditions |
| Disposal | Recyclable kraft paper; separate PE film for barrier version |
Pictures for reference of the workshop for Valve Cement Bags:
Quality Control & Order Support for Buyers
Pre-production sample approval before mass run;
Batch test report available, including strength, dimension, and visual inspection;
Customization: size, ply count, moisture barrier, printing artwork, valve modification;
MOQ negotiation; free sample for lab and line trial;
Packing of empty sacks: bundled on pallets with shrink wrap for transit protection.
Important Buying Reminder
Please confirm 4 key pieces of information when placing an inquiry:
1. Loading weight (25kg / 40kg / 50kg)
2. Filling machine type & spout size
3. Target transport environment (land/sea freight, humidity level)
4. Printing requirements and certification needed
Hot Tags: valve cement bag, China valve cement bag, Stitched Kraft Paper Cement Bag, Sack Kraft Paper Bag, Kraft Paper Cement Bag, Open Cement Bag, Valve Cement Bag
