1. Definition and importance of heat sealing performance
Heat sealing performance refers to the ability of packaging film to form a firm seal after being heated. In frozen food packaging, the quality of heat sealing performance directly affects the sealing, barrier properties and shelf life of the packaging. If the heat sealing performance is poor, the packaging film cannot form a tight seal after being heated, which may lead to the penetration of gases such as oxygen and water vapor, and then cause problems such as oxidation and deterioration of food. Good heat sealing performance is one of the key factors to ensure the quality and safety of frozen food.
2. Specific requirements for heat sealing performance
Heat sealing temperature
The heat sealing temperature refers to the lowest temperature at which the packaging film can form a seal after being heated. The heat sealing temperatures of different types of packaging films vary, but are usually within a certain range. In order to ensure the heat sealing effect, the heat sealing temperature of the packaging machine needs to be set within the heat sealing temperature range of the packaging film. If the heat sealing temperature is too low, the packaging film may not be completely melted and form a tight seal; if the heat sealing temperature is too high, it may cause the packaging film to melt excessively, deform or even burn.
Heat seal strength
The heat seal strength refers to the strength of the sealing area formed by the packaging film after it is heated and sealed. This strength needs to be large enough to prevent leakage when the packaging is subjected to external forces during transportation and storage. The size of the heat seal strength is related to factors such as the material, thickness, heat seal temperature and heat seal time of the packaging film. In order to ensure the heat seal strength, these factors need to be strictly controlled during the packaging process.
Heat seal width
The heat seal width refers to the width of the sealing area formed by the packaging film after it is heated and sealed. This width needs to be large enough to ensure the reliability of the seal. If the heat seal width is too narrow, it may cause a weak seal; if the heat seal width is too wide, it may waste materials and increase costs. During the packaging process, the appropriate heat seal width needs to be determined according to actual needs.
Heat seal speed
The heat seal speed refers to the time required for the packaging machine to form a seal. This speed needs to be fast enough to improve packaging efficiency. The heat seal speed also needs to match the heat seal performance of the packaging film to ensure the sealing effect. If the heat seal speed is too fast, the packaging film may not be completely melted and form a tight seal; if the heat seal speed is too slow, it may reduce packaging efficiency and increase costs.
3. Factors affecting heat sealing performance
Material of packaging film
Frozen Packaging Film of different materials has different heat sealing performance. Polyethylene (PE) film has better heat sealing performance, while polypropylene (PP) film has relatively poor heat sealing performance. When choosing packaging film, it is necessary to determine the appropriate material according to actual needs.
Thickness of packaging film
The thickness of packaging film will also affect its heat sealing performance. Generally speaking, thicker packaging film has greater heat sealing strength, but it may also lead to problems such as increased heat sealing temperature and reduced heat sealing speed. During the packaging process, it is necessary to determine the appropriate packaging film thickness according to actual needs.
Parameters of heat sealing equipment
The parameter setting of heat sealing equipment will also directly affect the heat sealing performance of packaging film. The settings of parameters such as heat sealing temperature, heat sealing pressure, and heat sealing time need to be adjusted according to the heat sealing performance of packaging film. If the parameters are set improperly, it may lead to poor heat sealing effect.
Environmental conditions
Environmental conditions will also affect the heat sealing performance of packaging film. Excessive humidity may cause the surface of packaging film to be moist, thereby affecting the heat sealing effect; too low temperature may cause the packaging film to become brittle and reduce the heat sealing strength. During the packaging process, environmental conditions need to be strictly controlled to ensure the heat sealing effect.
4. Methods to improve heat sealing performance
Choosing the right packaging film
Choosing the right packaging film material and thickness according to actual needs is the basis for improving heat sealing performance. When choosing, factors such as food characteristics, packaging requirements and cost need to be considered.
Optimizing heat sealing equipment parameters
The heat sealing effect can be optimized by adjusting the parameters of the heat sealing equipment (such as heat sealing temperature, heat sealing pressure, heat sealing time, etc.). During the adjustment process, multiple tests are required to determine the best parameter settings.
Improving environmental conditions
The heat sealing performance of the packaging film can be further improved by controlling environmental conditions (such as humidity, temperature, etc.). Dehumidification equipment can be used to reduce humidity in environments with high humidity; heating equipment can be used to increase temperature in environments with low temperatures.
Using additives
Some special additives can be added during the production process of the packaging film to improve its heat sealing performance. Adding heat sealing accelerators can reduce heat sealing temperature and increase heat sealing strength; adding antioxidants can extend the service life of the packaging film and prevent it from aging.