Heat Sealing

Heat sealing is a packaging process that uses heat to melt the surface of thermoplastic materials (such as PE, PP, PET plastic films or composite films), then applies pressure to bond them together after cooling. In foreign trade, heat sealing is commonly used in flexible packaging bags, sealing films, blister packaging, etc., for products such as food, daily necessities, and electronics. Usage scenarios include: when export goods need moisture-proof, dust-proof, or tamper-proof packaging, heat-sealed bags or films are used; when customers require packaging to be airtight to extend shelf life. Precautions: heat sealing temperature, pressure, and time must be adjusted according to material thickness and melting point to avoid burning through the material from excessive temperature or weak seals from insufficient temperature; heat seal strength must be verified by peel testing and must comply with the destination country's packaging safety and environmental regulations (such as FDA, EU 10/2011). Difference from 'cold sealing': cold sealing uses adhesive and requires no heating, making it suitable for heat-sensitive materials; difference from 'ultrasonic sealing': the latter uses high-frequency vibration friction to generate heat and is suitable for thicker or special materials. Heat sealing is a common keyword in packaging clauses in foreign trade contracts and letters of credit; non-compliance may lead to rejection or claims.