Four side sealed bag (4 side seal bag, Four square seal bag), is a common form of plastic packaging. It is made by heating and bonding the two edges of a film material (such as polyethylene PE, polypropylene PP, or other composite film materials) together to form a bag with four sealing edges. This design gives the bag better sealing and moisture resistance and is suitable for a wide range of product packaging needs. The top end of the four side sealed bag is usually designed with an easy tear opening or equipped with a self-seal strip, making it easy for consumers to open and reseal the bag. Four side sealed bag has the following features:

  1. Excellent sealing performance: through the full circumference sealing treatment, the four side sealed bag can effectively prevent the intrusion of air, moisture and external pollutants, to maintain the freshness and purity of the internal items, especially suitable for products with high requirements for moisture and oxidation resistance.
  2. Material diversity: According to the characteristics of the packages, different film materials can be selected, including transparent film, aluminium-plated film, aluminium foil film, etc., to meet the special needs of different products in terms of barrier, light transmission, UV protection and so on.
  3. Cost-effectiveness: Compared with other complex forms of packaging, the production process of four side sealed bags is relatively simple, with high material utilisation, enabling large-scale automated production, thus reducing costs.
  4. Convenience: four side sealed bags are designed to be flexible and can be equipped with hanging holes, tear lines, self-sealing strips, etc., which makes them easy to carry, open and reuse, and enhances the user experience.
  5. Wide range of applications: from food (such as dried fruits, tea, coffee beans) to pharmaceuticals, cosmetics, electronic parts and even chemical reagents, four-side sealed bags are widely used in a variety of industries due to their diverse characteristics and good protective performance.
Four-side seal bag