Heat sealing: The ideal solution for airtight food packaging

Heat sealing, also known as hot welding, is an essential technique in the field of food packaging. Whether you are a small manufacturer or a large brand, this method guarantees leak-proof, safe and durable packaging for your food products. But how exactly does this technology work and what are its advantages? This article guides you through the essential aspects of heat sealing and how it can optimize your food packaging.

1. Heat sealing: principle and operation

Heat welding (or heat sealing) is a process of fusing two plastic materials together using heat. This technique is used to create airtight seals on food packaging, ensuring optimum protection of products against air, moisture, and other contaminants. Heat sealing is particularly popular for custom flexible packaging because it provides a perfect seal and a high-quality aesthetic finish.

The process involves applying heat to the surfaces of the plastic films to be sealed. When these surfaces melt, they mix together, forming a stable bond that solidifies after cooling. This welding is essential to guarantee the conservation and safety of packaged products, particularly in the food sector where freshness and hygiene are essential.

Compared to other packaging sealing techniques, such as cold sealing, heat sealing is often preferred for food packaging. It provides a stronger and more durable weld. Other methods, although effective for certain types of materials, cannot offer the same level of protection and sealing.

2. The benefits of heat sealing for food preservation

Preserving the freshness of your products

Heat sealing is essential to maintain the freshness of food products, especially those that are sensitive to spoilage from oxygen, moisture and light. For example, fresh food products benefit enormously from a tight seal that protects them against oxidation and bacterial growth.

Impact on the shelf life of packaged products

Effective heat sealing will extend the shelf life of food products. By hermetically sealing the package, heat sealing prevents air and moisture from entering the package. This is particularly useful for food packaging of sensitive products, such as fresh produce or items with a short shelf life.

3. The 3 key factors for a perfect hot weld

Ideal temperature for successful welding

Temperature is one of the three main factors that determine the quality of hot soldering. For a successful watertight weld, it is crucial to achieve an optimum temperature that allows the surfaces of the plastic materials to melt and bond properly. If the temperature is too low, the weld will be weak and the weld may tear. If it is too high, there is a risk of deterioration of the material and a loss of integrity. Temperature management is particularly important for the different types of plastic films used in food packaging, such as polyethylene or polypropylene. Each material reacts differently to heat, and precise control is essential for a perfect sealed weld.

Pressure: The key to a strong, reliable weld

The second crucial factor is pressure. Pressure is what allows the layers of plastic to touch and mix at the molecular level. Too little pressure will result in a weak seal, while too much pressure could damage the packaging or create leaks.

Time: control the heating time

The last key factor is time. The heating time required depends on the type of material used. For example, some materials, like polyethylene, react very quickly to heat and only need a few seconds to melt, while other thicker plastic films require a little more time. It is essential to respect these times to avoid uneven or insufficient welding.