Today we will explore a common but significant cognitive misconception in the field of packaging materials: confusing "heat sealing" with "hot bonding". This confusion is not only a misjudgment of material properties, but may also pose hidden risks to production quality and safety.

1、 Core concept clarification: The difference between heat sealing and heat bonding

Firstly, we need to clarify the essential differences between these two indicators:

1. Heat sealing - static and final sealing strength

·Definition: Refers to the peel strength of the sealed area when the material is cooled to room temperature after heat sealing, which is a static indicator.

·Testing method: Heat seal the material at a set temperature, pressure, and time, cool it down, and peel it off at a constant speed in a tensile machine. Measure the required force value, usually in N/15mm or lb/in units.

·Purpose: To ensure that the packaging can withstand internal and external pressure during storage, transportation, and stacking, maintain complete sealing, and prevent leakage.

2. Hot adhesion - dynamic, uncooled sealing strength

·Definition: Refers to the ability of the sealed area to resist peeling or damage when the material has not yet cooled and is still in a molten or semi molten state after heat sealing, which is a dynamic indicator.

·Testing method: Simulate the production line process, apply peeling or impact force to the seal that is still in a high temperature state within a very short period of time after heat sealing, and measure its resistance to damage.

·Purpose: To ensure that the newly sealed packaging can immediately withstand the impact of the contents, production line tension, and internal air pressure after leaving the heat sealing knife, avoiding "instantaneous package breakage".

A simple analogy:

·The heat sealing strength is like a dry adhesive, determining the final bonding strength.

·The thermal adhesive strength is like a wet glue, testing whether it has sufficient temporary support before curing.

2、 The risk and hidden dangers of mistaking heat sealing for heat bonding

If the material only has good heat sealing strength and insufficient thermal adhesion energy, and is incorrectly replaced during evaluation, it may cause the following problems in high-speed automation production:

1. Production line breakage and pollution

·In the vertical filling packaging machine, when the material falls into the just sealed bag bottom, it generates an impact. If the thermal adhesion is insufficient, it can easily cause the bag bottom seal to break and the product to leak.

·Leakage can contaminate equipment, increase the frequency of shutdown cleaning, affect efficiency, and even cause equipment failure.

2. Content deterioration and waste

·Instantly breaking the packaging will immediately render the preservation, nitrogen filling, or vacuum packaging ineffective, allowing oxygen and water vapor to enter and cause food, medicine, or electronic products to deteriorate or lose their functionality.

·If such damage is not detected before leaving the factory, it may lead to customer complaints and cause brand reputation damage when it enters the market.

3. Sealing failure caused by internal pressure

·Hot filled or inflatable packaging generates internal pressure due to the expansion of the contents or gas at the moment of sealing. When the thermal adhesion is insufficient, the seal is easily stretched open, resulting in bulging, air leakage, or bursting.

·This type of packaging is more prone to compression and damage during subsequent packing, leading to chain problems.

4. Limited production line speed

·The higher the production line speed, the higher the requirement for thermal adhesive strength.

·If production is forced to slow down due to insufficient thermal viscosity, it will affect equipment capacity and increase unit costs.

5. Quality misjudgment and supply chain disputes

·If the supplier only provides heat sealing strength data and actual production relies on thermal adhesion performance, once there is a package breakage, both parties are prone to liability disputes due to inconsistent standards.

·Production enterprises may find it difficult to effectively hold accountable due to a lack of basis for thermal adhesion testing.

6. Wrong orientation in research and selection

·Relying on heat sealing data for material selection or formulation adjustment may lead to the wrong selection of materials that are not suitable for high-speed production, or affect thermal adhesion performance in pursuit of high heat sealing strength, resulting in technical misunderstandings.

3、 Conclusion and Suggestions

Heat sealing and heat adhesion are two different dimensions for evaluating the sealing performance of packaging materials, which complement each other and cannot be replaced by each other. The ideal material should have both good thermal adhesion performance (to ensure high-speed production) and sufficient heat sealing strength (to ensure the firmness of the finished product).

Suggestions for manufacturing enterprises:

1. Correctly understand the differences in indicators

Strengthen the training of procurement, quality inspection, and production personnel, clarify the different meanings and application scenarios of heat bonding and heat sealing.

2. Equipped with professional testing equipment

A dedicated thermal adhesion tester should be used to evaluate the production applicability of materials, such as the Jinan Sike HTT-3701 thermal adhesion tester, to avoid relying solely on data from the heat sealing instrument.

3. Establish internal testing standards

Develop material inspection standards and require suppliers to provide both thermal bonding strength curves and heat sealing strength data.

4. Simulate the actual conditions of the production line

During testing, parameters such as temperature, pressure, cooling time, and peeling speed of the production line should be restored as much as possible.

5. Strengthen supply chain collaboration

Clearly express the demand for thermal adhesion performance to suppliers and work together to improve overall performance from raw materials and formulas.

Correcting the misconception of "replacing heat bonding with heat sealing" is an important step in improving packaging quality, ensuring production efficiency, and maintaining brand image. Only by establishing scientific knowledge and equipping corresponding detection methods can material risks be effectively identified and stable production be achieved.

Thank you for reading this issue. Follow Jinan Sike and "Sike Membrane Surgery Museum" to learn about the latest developments in testing technology and assist in product development and quality improvement.

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