Bubble bags, widely used as cushioning materials in logistics packaging, primarily function to absorb impact through their internal independent bubble structure, protecting products from damage caused by vibration, collisions, or drops. However, in low-temperature environments, the physical properties of plastic materials change significantly. Molecular mobility weakens, intermolecular forces increase, leading to hardening, embrittlement, and decreased flexibility. This change can cause the bubble structure to shrink, deform, or even rupture, thus weakening the bubble bag's cushioning performance. To ensure bubble bags function stably in low-temperature environments, comprehensive optimization is needed across multiple dimensions, including material selection, structural design, manufacturing processes, storage, transportation, and usage methods.
Material selection is fundamental to ensuring low-temperature stability. Traditional bubble bags often use polyethylene (PE) as the base material due to its good flexibility, corrosion resistance, and low-temperature resistance, maintaining stable performance in normal low-temperature environments. However, for extreme low-temperature conditions, modified polyethylene or copolymer materials can be used to improve the material's resistance to embrittlement by adjusting the molecular chain structure. For example, adding toughening agents or nanofillers can enhance the material's toughness at low temperatures, reducing the risk of rupture due to stiff molecular chains. Furthermore, avoid using materials containing plasticizers, as they may precipitate at low temperatures, further reducing material performance.
Structural design is crucial for bubble stability. The size, density, and distribution of bubbles directly affect their low-temperature resistance. While larger bubbles provide stronger cushioning, they are more prone to rupture due to internal and external pressure differences at low temperatures; smaller, high-density bubbles, on the other hand, can reduce the risk of rupture by dispersing pressure. Therefore, for low-temperature environments, bubble design can be optimized by using smaller, denser bubble structures and ensuring uniform bubble distribution to avoid localized stress concentration. Simultaneously, double-layer bubble structures or composite bubble layer designs can further enhance impact resistance; even if one layer of bubbles ruptures, the other layer can still provide protection.
Refined control of the production process is a key factor in ensuring bubble stability. During bubble formation, temperature, pressure, and cooling rate must be strictly controlled. In low-temperature environments, if the cooling rate is too fast, the bubble walls may thin or rupture due to uneven contraction; while if the cooling rate is too slow, the bubble size may become too large, reducing stability. Therefore, it is necessary to optimize process parameters, such as adjusting extrusion temperature, die pressure, and cooling air velocity, to ensure that the bubble walls are uniform and have a certain thickness. Furthermore, using co-extrusion technology to add a buffer layer between the bubble layer and the base layer can enhance the overall structure's low-temperature resistance.
Proper management of storage and transportation conditions can effectively reduce the impact of low temperatures on bubble bags. Bubble bags should be stored in a dry, well-ventilated warehouse, avoiding direct sunlight and rain, and kept away from corrosive substances such as acids, alkalis, and oils. The recommended storage temperature is between -15℃ and 40℃, avoiding prolonged exposure to extreme low temperatures. During transportation, if handling at low temperatures is necessary, the bubble bag can be wrapped with insulating material, or heating equipment can be used to maintain the packaging temperature to prevent material embrittlement. Additionally, avoid contact between the bubble bag and sharp objects to prevent bubble bursting due to external pressure.
The proper use of the product is also crucial. When sealing the box, ensure that the bubble bag fits tightly against the product to prevent uneven pressure on the bubbles due to shaking. For heavy or fragile products, multi-layer or cross-wrap techniques can be used to enhance protection. Avoid directly stretching or folding the bubble bag at low temperatures to prevent breakage due to material hardening. If handling at low temperatures is necessary, allow the bubble bag to warm to room temperature until it regains its flexibility before packaging.
For specific applications, the low-temperature stability of the bubble bag can be further improved by adding functional coatings or composite materials. For example, applying a waterproof coating to the bubble layer prevents material performance degradation due to moisture; composite materials such as aluminum foil or kraft paper enhance the bubble bag's tear resistance and insulation. While these improvements increase costs, they significantly improve the reliability of the bubble bag in extreme environments.
The stability of bubble bags at low temperatures requires a collaborative approach involving material optimization, structural design, process control, storage management, usage guidelines, and functional improvements. Through scientific selection and appropriate application, bubble bags can fully maintain their cushioning performance under low-temperature conditions, providing reliable protection for products.
