In the vast field of plastic packaging, the sealing method, as a key factor to determine the function and use experience of plastic bags, shows a rich variety of forms. Different sealing methods have their own advantages to meet a variety of packaging needs and application scenarios.

Heat sealing is a very common and efficient means of sealing. It uses special heat sealing equipment, such as heat sealing machine, to heat and pressure the sealing part of the plastic bag. Under the action of appropriate temperature and pressure, the material at the seal of the plastic bag is heated and fused and adhered to each other, and a firm seal is formed after cooling. This sealing method has many significant advantages, its sealing strength is extremely high, can withstand greater external force pulling and extrusion, effectively prevent the leakage of items in the bag. It is widely used in the large-scale production packaging process of food, medicine, daily chemical and many other industries, such as food packaging bags, pharmaceutical aluminum-plastic composite bags, etc., which are mostly heat-sealed to ensure the sealing and stability of products in storage, transportation and sales.

Self-sealing sealing is favored by consumers for its convenience. This type of closure is usually pre-arranged at the mouth of the plastic bag with a special concave and convex groove structure, and is equipped with a matching plastic zipper. The user only needs to gently slide the zipper along the concave and convex groove to achieve a quick closure of the bag mouth. The convenience of ziplock bags makes them widely used in daily life, such as snack packaging, small objects storage and other scenes can be seen everywhere. After taking some items, consumers can easily seal the bag again, effectively maintaining the freshness and integrity of the items in the bag, preventing moisture, oxidation or scattering.

The pressure sealing method is relatively simple, and a certain pressure is applied to the sealing of the plastic bag to make the bag mouth material closely fit together, so as to achieve the purpose of sealing. Although the sealing strength of this method is not as good as heat sealing, because of its simple operation and low cost, it is still used in some temporary packaging or simple packaging scenarios with low sealing requirements, such as ordinary stationery bags, simple gift bags and so on.

In addition, there are advanced sealing technologies such as ultrasonic sealing and electromagnetic induction sealing. Ultrasonic sealing uses high-frequency vibration to make the material molecules at the plastic bag sealing interface rub together to generate heat, and then achieve melting sealing, which is suitable for the automatic production line with high sealing precision and speed. Electromagnetic induction sealing is mainly used in composite plastic bags containing metal foil, the heat generated by electromagnetic induction makes the aluminum foil at the seal and the plastic layer fusion, often used in high-end cosmetics, health products and other packaging, can effectively provide anti-counterfeiting and fresh-keeping functions.

The diversity of plastic bag sealing methods provides flexible packaging solutions for different industries and different scenarios, which effectively promotes the prosperity and development of the plastic packaging industry and meets the diversified packaging needs of modern society.