Author: Site Editor Publish Time: 25-02-2026 Origin: Site
In cold chain logistics, packaging bags face a test akin to a "baptism of ice and fire." From the -40°C deep temperature of the quick-freezing production line to the 40°C temperature difference at the end of the delivery process in summer, ordinary packaging materials are extremely prone to cracking, delamination, or air leakage at the seal.
Once packaging fails, a product's freshness can collapse within minutes. Today, we delve into the bottom of the production line to reveal how high-performance cold chain packaging safeguards the last line of defense under extreme physical conditions.
Most ordinary plastic films (such as standard BOPP) rapidly reach their glass transition temperature when exposed to temperatures below -18°C, becoming as brittle as glass.
The Secret of the Material: High-quality cold chain bags must contain a high proportion of NY (nylon) or a special tough PE (polyethylene) composite. Nylon possesses excellent puncture resistance and flexibility at low temperatures.
Avoiding Pitfalls: Many low-priced bags reduce the thickness of the nylon layer to cut costs. The testing method is simple: place the bag in a -20°C freezer for 24 hours, then immediately perform a drop test and observe whether any fine cracks appear at the corners of the bag.
Temperature variations cause materials to expand and contract. If the molecular chain bonding at the heat-sealed area is insufficient, the internal stress caused by temperature fluctuations will directly tear the seal.
Heat-Sealing Window: Professional-grade cold chain packaging uses narrow-distribution polymer technology. This means the material has a wider heat-sealing temperature range on the sealing machine, ensuring "molecular-level fusion" at every weld, even during high-speed filling.
Contamination-Resistant Sealing: Cold chain foods often contain moisture or oil. Our technology ensures a strong seal even if juice or oil is accidentally spilled at the seal, preventing "frost buildup" caused by cold air entering.
The loss of freshness often begins with molecular penetration. Moisture loss (drying) and oxygen penetration under cold chain conditions are the main causes of meat discoloration and seafood odor.
High Barrier Coating: We incorporate EVOH (ethylene-vinyl alcohol copolymer) into our multi-layer composite. This material has extremely low oxygen permeability, completely isolating the internal microenvironment of the packaging from the external environment.
Physical Performance Analysis: At 25°C, the oxygen permeability of the high-performance barrier film can be controlled to ≤1.0 cm³/(㎡·24h·0.1MPa).
Faced with the complexities of the cold chain environment, a reliable testing report is more powerful than verbal promises. When customizing your solution, please pay close attention to the following three key indicators provided by the supplier:
Drop Resistance Test: Undamaged after a free fall from a height of 1.2 meters at -18°C.
Coefficient of Friction (COF): Ensures smooth operation without slippage on automated production lines.
Peel Strength: Ensures that multi-layered composite materials do not delaminate after repeated freeze-thaw cycles.
