What are the respective advantages and disadvantages of square valve bags produced using the glued-bottom process and heat-sealing process?
Release time:
2026-02-05
Comparison of Advantages and Disadvantages Between Glued-Bottom and Heat-Sealed Square Valve Bags
Glued-Bottom Valve Bags
Core Principle: Environmentally friendly water-based adhesive bonds the overlapping bottom seams, followed by pressing and drying to set the shape. This is the mainstream industrial process.
Advantages:
① High adaptability, suitable for all substrates including pure paper and paper-plastic composites;
② Low equipment costs and high mass production efficiency, with overall manufacturing costs 10%-20% lower than heat-sealing;
③ Stable load-bearing capacity after adhesive curing, meeting standard industrial load requirements of 25-50kg;
④ Mature process allows flexible after-sales maintenance and capacity adjustments, suitable for small-to-medium batches with multiple specifications.
Disadvantages:
① Inferior sealing and moisture resistance compared to heat sealing; adhesive layer may exhibit slight leakage in high-humidity environments;
② Requires water-based adhesive and includes a drying/curing step, adding one more production stage than heat sealing;
③ Adhesive residue may remain, necessitating additional testing for packaging high-purity materials.
Heat-Sealed Valve Bags
Core Principle: Plastic layers (PE-coated film / PP woven fabric) at the bag bottom fuse through 120-180°C hot pressing without adhesive layers.
Advantages:
① Excellent sealing, moisture resistance, and leak prevention; suitable for high-humidity, prone-to-clumping, and high-cleanliness materials;
② Adhesive-free construction leaves no residue on the bag bottom, meeting packaging standards for food additives, fine chemicals, and similar materials;
③ Eliminates drying requirements, simplifying production while enhancing weather resistance for long-distance export shipments;
④ Plastic fusion bonding provides superior tear resistance compared to adhesive layers.
Disadvantages:
① Limited adaptability, only suitable for composite substrates with plastic layers; cannot produce fully paper valve bags;
② High equipment precision requirements; heat-sealing molds must be custom-made to specifications, resulting in higher initial equipment investment compared to adhesive-bottom processes;
③ Higher overall production costs, and strict operational requirements for high-temperature hot pressing, prone to issues like incomplete sealing and substrate scorching.
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