Square valve bags, widely used in modern packaging, rely heavily on valve design to ensure effective sealing during filling, thus impacting product preservation and transportation safety. Optimizing valve design requires comprehensive consideration of material selection, structural innovation, dimensional matching, process control, and auxiliary sealing measures to achieve efficient sealing during filling.
Material selection is fundamental to improving valve sealing performance. The valve area must withstand pressure impacts and material friction during filling; therefore, the material must possess sufficient strength and wear resistance. Simultaneously, to ensure a tight seal, the material should also exhibit good flexibility and elastic recovery, quickly returning to its original shape after valve closure to fill any potential micro-gaps. For example, using thermoplastic resins such as high-density polyethylene (HDPE) or polypropylene (PP), with the addition of appropriate elastomers or plasticizers, can significantly improve the overall performance of the valve material, providing a material guarantee for effective sealing.
Structural innovation is key to optimizing valve design. Traditional square valve bags typically employ straight or angled valve designs. While these structures provide basic sealing during filling, they are prone to leakage when handling high-speed filling or powdery materials. Therefore, a more complex structure can be considered, such as a double-layer valve design. The outer layer is a rigid support structure, while the inner layer is a flexible sealing layer. The two work together to ensure both overall valve strength and improved sealing flexibility. Alternatively, valves with elastic sealing rings can be designed. The deformation of the sealing ring fills the gap between the valve and the bag body, achieving a more secure seal.
Size matching is equally crucial. The valve size must precisely match the valve size of the filling equipment. Too large or too small a size will affect the sealing effect. An overly large valve diameter will prevent the valve from fully fitting the bag when closed, creating a leakage path; an underly small diameter will increase filling resistance and may even damage the valve or the filling equipment itself. Therefore, when optimizing the valve design, the optimal valve size must be precisely calculated based on the specific parameters of the filling equipment to ensure a tight fit between the valve and the filling port.
Process control also significantly impacts valve sealing performance. During valve manufacturing, parameters such as heat-sealing temperature, pressure, and time must be strictly controlled to ensure the heat seal strength between the valve and the bag body. Excessive heat-sealing temperature or pressure may lead to over-melting of the material, creating weak points; insufficient heat-sealing temperature or pressure will affect the seal's strength. Simultaneously, attention must be paid to the flatness and smoothness of the heat-sealed area to avoid poor sealing due to surface roughness. By optimizing process parameters, a perfect bond between the valve and the bag body can be achieved, providing process assurance for the sealing effect.
Auxiliary sealing measures are also an effective means to improve valve sealing performance. In valve design, auxiliary sealing structures can be added, such as sealing lips or sealing grooves. The compression effect when the valve is closed causes the sealing material within the sealing lip or groove to deform, filling gaps and achieving a secondary seal. In addition, sealant can be applied to the outside of the valve or sealing patches can be pasted to further enhance the sealing effect. These auxiliary sealing measures, though simple, effectively improve the overall sealing performance of the valve.
Optimizing the design of square valve bags also requires consideration of actual usage scenarios. Different industries have different sealing requirements for valve bags. For example, the food industry has high hygiene standards, while the chemical industry focuses more on corrosion resistance. Therefore, when optimizing the valve design, it is necessary to select appropriate materials and structures based on the characteristics of the target industry to ensure that the valve bag meets sealing requirements while also adapting to the specific usage needs of the industry.
