How Well Do Food Packaging Boxes Seal?

Key indicators of food packaging box sealing performance: Sealing performance directly affects food safety and shelf life, and is mainly measured by the following indicators:

1. Oxygen Transmission Rate (OTR): The OTR of high-quality plastic composite materials can be lower than 5 cm³/m²·24h (refer to GB/T 1038-2000), effectively delaying food oxidation.

2. Water Vapor Transmission Rate (WVTR): The WVTR of aluminum foil composite packaging is typically <0.1 g/m²·24h (ASTM E96 standard), suitable for high humidity-sensitive foods.

3. Sealing Strength: The peel strength of the heat-sealing process must be ≥15 N/15mm (GB/T 23508-2009) to ensure no cracking during transportation.

Key Factors Affecting Sealing Performance

1. Material Selection:

- Plastics (such as PET/PE) are low-cost but have generally poor sealing performance, mostly used for short-term fresh foods;

- Aluminum-plastic composites have excellent barrier properties and are commonly used for high-end products such as milk powder and coffee.

2. Process Technology:

- Heat sealing temperature control deviation within ±2℃ (industry practice data). Too high a temperature can cause material deformation, while too low a temperature can easily lead to leakage;

- Nitrogen-filled packaging can reduce residual oxygen content to below 0.5% (refer to ISO 14855), significantly extending shelf life.

Common Problems and Solutions in Practical Applications

1. Air Leakage: Approximately 3% of packaging leaks are due to mechanical damage or sealing contamination (data from the 2023 issue of *Packaging Engineering* journal), which can be monitored in real time using an online leak detector;

2. Temperature Adaptability: Under conditions of -18℃ freezing or 100℃ retorting, some materials may experience sealing failure, requiring the use of heat-resistant special films.