Adhesive Engineering in Multi-Wall Industrial Paper Sacks: Bottoming and Longitudinal Seaming for Heavy-Duty Packaging
In industrial multi-wall kraft paper sacks (25 kg to 50 kg capacity for cement, building chemicals, flour, and industrial powders), the longitudinal side seam and the folded bottom (bottoming) bear extreme dynamic hydrostatic shock during high-speed rotary spout filling and pallet drop impact (ISO 7965). Automated tuber and bottomer converting machinery operating at 300–400 sacks/min relies on high-solids water-based synthetic polymer dispersions and modified starch hybrid adhesives (Jowacoll®) that deliver deep fiber-tearing bonds, fast initial tack, and zero dust leakage under rigorous handling.
Heavy-duty multi-wall paper sacks (2 to 4 plies of high-porosity kraft paper) carry demanding bulk commodities such as cement, dry mortar, flour, and granular chemicals. Preserving package integrity during high-speed automated packing and transport hinges on tailored bottoming pastes and seaming dispersions.
1. Dynamic Loading in Multi-Wall Sacks and Adhesive Demands
Hot cement discharged at 70°C exerts acute internal bursting pressure upon sack bottom folds. In standardized drop tests (ISO 7965 from 1.2 m), the cured adhesive film must retain sufficient elasticity to absorb mechanical shock without brittle fractures, ensuring 100% paper fiber tear.
2. Tuber Operations: High-Speed Longitudinal Seaming and Cross Pasting
High-speed tuber converting equipment requires distinct viscosity profiles:
| Application Area | Adhesive System | Viscosity (mPa.s / 20°C) | Open Time Window | Mechanical Performance |
|---|---|---|---|---|
| Longitudinal Seaming | Synthetic Polymer Dispersion (Jowacoll®) | 1,200 – 2,500 | Very Fast (1 – 3 sec instant tack) | High shear resistance on line |
| Cross Pasting (Ply-to-Ply) | Modified Starch / PVA Hybrid | 800 – 1,500 | Moderate (3 – 6 sec) | Prevents ply slippage during folding |
| Bottoming Paste | High-Solids Starch Dispersion | 3,500 – 7,000 | Controlled (5 – 15 sec) | Deep fiber-tearing failure mode |
| Valve & Bottom Patch | Heat-Resistant Packaging Hot Melt | 1,500 – 3,000 (at 160°C) | Short (0.5 – 1.5 sec) | Zero dusting, high thermal hold |
7. Frequently Asked Questions (FAQ)
To optimize tuber and bottomer line efficiency, contact the Koçak Endüstri technical service team.
Adhesive Engineering in Multi-Wall Industrial Paper Sacks: Bottoming and Longitudinal Seaming for Heavy-Duty Packaging hakkında merak edilenler
What causes cement sack bottoms to burst during filling?
Shallow surface adhesion without fiber penetration. High-solids modified starch-PVA hybrids penetrate deep into kraft capillaries to deliver structural fiber tear.
How should adhesive viscosity be managed in hot summer conditions?
Accelerated water evaporation risks premature skinning on applicator rollers. Use humidity-tolerant formulations with extended open times.
Are adhesives for flour and food sacks odor-free?
Yes. Jowacoll dispersion adhesives are completely odorless and free of plasticizers, complying fully with BfR XXXVI and FDA 175.105 food contact mandates.
Can standard starch paste bond PE barrier liners inside kraft sacks?
No. Bonding polymer film to paper requires specialized synthetic co-polymer dispersions formulated for low-surface-energy substrates.
Technical resources and verification
The content has been prepared in Turkish with the technical experience of Koçak Endüstri, based on the following manufacturer resources.
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