How does shrink film maintain stable protective performance in cold chain or high-temperature transportation environments?
Publish Time: 2025-12-17
Plastic shrink film, as a key material in modern packaging systems, is widely used in the sales and logistics of industries such as food, beverages, daily chemicals, and electronics. Its core function is not only aesthetic wrapping, but also providing stable, dustproof, moisture-proof, and damage-proof protection for products through high puncture resistance, good shrinkage rate, and moderate shrinkage stress. However, when faced with extreme temperature environments—such as cold chain transportation or high-temperature warehousing/cross-border transportation—ordinary shrink film is prone to problems such as brittleness and cracking, excessive softening, shrinkage failure, or stress relaxation. Shrink film, through material modification, multi-layer co-extrusion structure, and precise process control, ensures reliable protective performance across a wide temperature range.1. Low-Temperature Toughness: Resisting the Risk of Embrittlement in Cold ChainsIn frozen foods, biological products, or winter logistics in northern regions, shrink film needs to be exposed to environments below 0°C for extended periods. Under these conditions, the molecular chain movement of ordinary polyethylene or polyvinyl chloride films is restricted, causing the material to harden and become brittle, making it susceptible to perforation or tearing even with slight external force. To address this issue, modern cold chain-grade shrink films often utilize blends of linear low-density polyethylene (LLDPE) and metallocene polyethylene (MCPE), or incorporate elastomer toughening agents. These materials exhibit lower glass transition temperatures, maintaining flexibility and impact resistance even at -30°C. Simultaneously, optimized blown film processes control crystallinity, preventing the formation of large crystalline regions and further enhancing low-temperature puncture resistance, ensuring the intact packaging of frozen products during handling and stacking.2. High-Temperature Stability: Preventing Softening, Deformation, and Stress AttenuationConversely, in long-distance summer transport, tropical warehousing, or industrial settings near heat sources, ambient temperatures may exceed 50°C. If the shrink film's heat resistance is insufficient, the following problems may occur: first, the film softens and adheres, causing palletized goods to collapse; second, the shrunken film loses tension due to thermal relaxation, failing to continue securing products; and third, excessive heating may trigger secondary shrinkage, compressing fragile items. To address this, high-performance high-temperature shrink films often utilize cross-linked polyethylene or heat-modified POF materials, employing multi-layer co-extrusion technology to construct a "rigid-flexible" structure—the outer layer provides high melting point and dimensional stability, while the inner layer ensures heat-sealing strength and shrinkage response. Some products also incorporate heat-resistant stabilizers to inhibit molecular chain slippage at high temperatures and maintain long-term shrinkage stress.3. Wide Temperature Range Adaptability: Synergistic Design of Materials and StructureShrink films are not designed for a single extreme environment but possess wide temperature range adaptability. For example, a beverage tray film used for global distribution needs to withstand both the cold storage conditions of Nordic winters and the container environments of the Middle East during summer. These films typically employ a three- or five-layer co-extrusion structure: a core layer of high-toughness LLDPE/mPE ensures low-temperature performance, a surface layer of high-melting-point HDPE or special POF provides high-temperature support, and adhesive and barrier layers can be added in between. This "sandwich" design allows the film to maintain mechanical integrity, shrinkage stability, and surface smoothness within a temperature range of -25℃ to +60℃, preventing packaging failure due to temperature fluctuations.4. Enhanced Auxiliary Performance: Addressing Complex Transportation ChallengesBesides temperature adaptability, cold chain and high-temperature environments are often accompanied by high humidity, UV radiation, or chemical contact. Therefore, high-end shrink film integrates multiple protective functions: adding anti-UV masterbatch to prevent aging from outdoor sun exposure; using anti-fogging agents to prevent condensation from affecting transparency in the cold chain; and employing an anti-static formula to prevent dust adsorption or damage to electronic components. These seemingly small details significantly improve the reliability of packaging in real-world logistics scenarios.In the modern logistics system characterized by drastic temperature differences and complex environments, shrink film is no longer just a simple "plastic coat," but a smart packaging solution integrating materials science, structural engineering, and environmental adaptability. Through targeted material selection, precise multi-layered structures, and rigorous performance verification, modern shrink film successfully overcomes challenges ranging from freezing temperatures to scorching heat, building an invisible yet robust protective barrier for the safe circulation of goods globally.
