What is the reason why a delivery bag won’t open even if it touches water?

The main function of express bags is to express packages, and the rapid development of online shopping has led to the widespread use of express bags in logistics packaging and transportation! The sealing degree is very high, and the sealing method is also convenient. When we receive parcels, we occasionally see that even if the parcel bag is broken, the seal usually does not burst. It can be seen that hot melt adhesive has a strong adhesion force on the parcel bag, but long-term exposure to water can also easily cause the adhesive layer to break. However, there is rarely a problem of water splitting on parcel bags. What is the reason? Let’s take a look together
The hot melt adhesive used for express delivery bags actually needs to have several important properties, and one of them is the material breaking effect. When producing and processing express delivery bags, the sealing area of the bag that needs to be glued will not be broken by the heated glue, but there will be a certain degree of damage to the surface of the express delivery bag that is already plastic, which happens to be the effect we need to achieve when gluing. The hot melt adhesive used in this type of express delivery bag is actually pressure-sensitive hot melt adhesive. Even at room temperature, it has good initial viscosity. Just a slight pressure during sealing is needed to seal it firmly, ensuring the sealing effect and intact packaging of the item. So every time the package is opened, there is a situation where it is torn directly from the side of the seal. This is because the plastic used to make the package bag has relatively loose molecules, and with just a little force, the thin layer of plastic can be torn open. But the seal is very firmly stuck and difficult to tear open!! This is also a very good breaking effect.
Because this loose molecular structure can form a large space with hot melt adhesive, the plastic surface is damaged by heat during gluing. After the plastic molecular adhesive cools down, it can adhere and form a stable structure again, so it is very firm, even if the entire express bag is soaked in water, it is difficult for the seal to open.
Moreover, the surface of the express bag itself is relatively smooth, and usually water droplets will slip away quickly without stopping. Even if it rains during transportation, there is no need to worry, as rain does not affect the sealing performance of the express bag opening. Of course, the bag itself needs to be sealed and undamaged during transportation before it can be used. Therefore, we can know that the bonding effect of hot melt adhesive on express delivery bags is still very good, and it is also a sticky force that we can feel when using it in our daily life.