paper bag production line

Paper shopping bags travel through some of the harshest environments a packaging material can encounter—cold storage warehouses, unheated delivery trucks in winter, outdoor retail pick-up areas, and refrigerated food service operations. An adhesive that performs perfectly on the factory floor but becomes brittle in these downstream environments is a liability waiting to become a seam failure. TONGDE 9021CD is a low temperature resistant hot melt adhesive developed specifically for kraft paper bag sealing, with a synthetic rubber base that maintains bond integrity and flexibility well below the temperatures at which standard EVA hot melts begin to stiffen.

The Cold Weather Failure Problem

Most hot melt adhesives used in paper bag production are EVA-based. EVA is an excellent general-purpose base polymer, but it has a well-documented tendency to lose flexibility at low temperatures. As ambient temperature drops, EVA bonds stiffen, then become brittle, and finally crack—releasing the seam and causing bag failure. For premium retail brands whose bags are used in shopping centers, street markets, and outdoor events during winter months, this is an unacceptable risk.

This is why bag manufacturers and brand packaging engineers increasingly specify flexible hot melt for paper bag applications. Synthetic rubber hot melts maintain their elastic properties across a much wider temperature range, providing reliable seam integrity in conditions that would cause EVA adhesives to fail.

Synthetic Rubber: The Flexibility Advantage

TONGDE 9021CD's synthetic rubber backbone is the key to its cold-weather performance. The polymer chain architecture of synthetic rubber provides:

• Inherent elasticity: The bond can flex without cracking when bags are handled in cold environments
• High peel resistance: Resistant to the peeling forces exerted on bag seams during carrying, even at low temperatures
• Excellent tack retention: Maintains adhesive contact with both kraft and coated paper surfaces across temperature fluctuations
• Cohesive strength: The internal strength of the adhesive layer resists splitting under sustained load

These properties combine to create seams that stay closed whether a bag is carried out of a warm boutique into a cold winter street, stored in a chilled distribution center, or used in refrigerated food retail environments.

Technical Specifications

The softening point of 90±5°C—lower than many EVA formulations—reflects the rubber base polymer's different thermal profile. This actually benefits paper bag production: lower softening point means the adhesive flows well at moderate temperatures, reducing energy consumption and minimizing heat stress on heat-sensitive coated paper and laminated bag stocks.

Substrate Coverage for Premium Bags

The best paper bag seam adhesives must bond to every substrate in the product mix. TONGDE 9021CD excels as a kraft paper bag sealing glue on:

• Natural and bleached kraft paper (standard retail shopping bags)
• Glossy and matte coated paper (premium branded bags)
• White cardboard stock (luxury boutique bags)
• Corrugated paper (reinforced heavyweight shopping bags)

This coverage means manufacturers can run a full day's production across different bag constructions without formula changes or tank purges.

Application Best Practices for Cold-Climate Markets

For customers supplying bags to cold-climate markets or refrigerated retail sectors, we recommend:

1. Test at use temperature: Seal a sample batch and condition it at the expected service temperature (e.g., 0°C or -10°C) for 24 hours, then apply load to verify seam strength.
2. Maintain adequate glue line thickness: A 0.3–0.5 mm bead provides sufficient adhesive mass to maintain flexibility at low temperatures.
3. Optimize application temperature: Running at 165–170°C balances good flow with minimal thermal stress on cold-climate grade laminated papers.

Related Products

For complementary paper bag closure options, explore our Hot Melt Adhesive for Air Filter Sealing and the full Filter Adhesive Range. For carton sealing on corrugated shipping cases, our Carton Sealing Adhesive provides optimized performance.

For industry guidance on paper bag manufacturing and performance testing, consult the TAPPI technical library and the Foodservice Packaging Institute.