Paper packaging external valve port plays a key role in the field of modern packaging. Its bonding strength with different types of paper packaging directly affects the integrity and functionality of the packaging.
First, different types of paper packaging have different surface characteristics. For example, the surface of corrugated board has a concave and convex corrugated structure. When this structure is combined with the external valve port, on the one hand, the undulation of the corrugation may hinder the close fit between the valve port and the board, resulting in a weak bond; on the other hand, if the shape of the corrugation can be reasonably utilized and a special bonding process is adopted, such as local reinforcement bonding at the peaks and valleys of the corrugation, the overall bonding strength can be increased.
For smooth cardboard packaging, it is relatively easy to achieve uniform and tight bonding between the valve port and the cardboard, but because the cardboard is relatively thin, it may be easy to tear when subjected to the tension of the valve port. It is necessary to consider additional reinforcement treatment in the bonding area, such as increasing the bonding area or using high-strength adhesives.
Secondly, the selection and use of adhesives are important factors affecting the bonding strength. For the external valve port of paper packaging, common adhesives include hot melt adhesives, white latex, etc. Hot melt adhesive cures quickly and can initially fix the valve port to the paper packaging in a short time, but there may be a problem of insufficient long-term stability; white latex has good flexibility and durability, but it takes a long time to dry. When choosing an adhesive, it is necessary to consider the type of paper packaging, the use environment, and the stress of the valve port.
For example, in food packaging, the safety and hygiene of the adhesive must also be considered. At the same time, the amount and method of applying the adhesive will also affect the bonding strength. Evenly and appropriately applied coating can ensure a good bonding effect, while too much or too little may lead to a weak bond.
Furthermore, the structural design of the external valve port has a significant effect on the bonding strength. The edge shape of the valve port, the presence or absence of reinforcing ribs or fixed wings, and other structures will change the bonding method with the paper packaging. For example, a valve port with a wide fixed wing can increase the contact area with the paper packaging, and can effectively improve the bonding strength through multi-point pasting or hot pressing. The serrated design of the valve port edge can increase the adhesion with the adhesive and prevent the valve port from being easily peeled off from the paper packaging when it is subjected to force.
In addition, the compatibility of the material of the valve port and the paper packaging also affects the bonding effect to a certain extent. For example, the thermal expansion and contraction coefficients of the plastic valve port and the paper packaging are different, which may cause the bonding to loosen in an environment with large temperature changes. It is necessary to consider reserving expansion space or using buffer materials for transition during design.
Finally, the test and evaluation method of bonding firmness is crucial to ensure the quality of paper packaging external valve port. Tensile test, shear force test and other methods can be used to simulate the external force that the valve port may be subjected to during actual use, and the bonding firmness can be evaluated by measuring the force required to separate the valve port from the paper packaging. According to the test results, the design of the valve port, the selection and use of adhesives, and the bonding process are optimized and adjusted to ensure that the paper packaging external valve port has sufficient bonding firmness on different types of paper packaging, meet the needs of product packaging, and reduce the occurrence of packaging leakage or damage.
