Double-walled heat-shrinkable tubes are called double-walled heat-shrinkable tubes because they have hot-melt adhesive on the inner wall. They have a double-layer structure. The outer layer is an EVA protective layer and the inner layer is sealed and waterproof hot-melt adhesive, so it is also called double-walled heat-shrinkable tubes. Heat shrink tubing. Double-wall heat shrink tubing has a unique waterproofing effect compared to ordinary heat shrink tubing and is often used in places that require sealing. However, some users do not pay attention to quality when choosing double-wall heat shrink tubing and only pursue price. From the appearance, it is impossible to tell whether the quality is good or bad, but if the aging after use does not meet the standard, it is easy to cause the glue to open, thereby failing to achieve the sealing function, causing a quality accident with great impact.

To figure out the reason why the double-wall heat shrinkable tube is glued open, there are three main factors: hot melt adhesive, EVA raw materials and shrinkage process:

    The first, of course, is to find the cause from the adhesive layer. Hot melt adhesive is an important part of the double-wall heat shrink tube. The peeling performance of the hot melt adhesive directly affects whether the double-wall heat shrink tube can be glued. If the hot melt adhesive used is unqualified or The stickiness of cheap recycled glue cannot meet the standard.

    Second, if the quality of hot melt adhesive can determine whether the glue is opened, then why does the quality of the outer layer also affect whether the double-wall heat shrinkable tube is glued? This is mainly due to the longitudinal shrinkage. If the quality of the outer layer is not controlled and the longitudinal shrinkage is too large, the hot melt adhesive will overflow seriously. Since the overflow part is not restrained by the outer layer, it is also one of the important reasons for the glue opening. .

    The third shrinkage process is a technical problem, which is also the best solution. It may be that the shrinkage temperature is too low and the shrinkage time is too short. The internal hot melt adhesive is not fully melted, and the optimal working condition of the hot melt adhesive is not reached. It is necessary to increase the shrinkage temperature and lengthen the shrinkage time.

    For double-wall heat shrinkable tubes, the inability to open glue is the basic quality indicator of double-walled heat shrinkable tubes. What to do if the glue has been opened? It is necessary to first rule out whether it is a quality problem with the double-wall heat shrinkable tube or a problem with the shrinkage process. Secondary heating shrinkage can be performed to fully melt the hot melt adhesive and achieve the best bonding state. If the glue does not open after being left for a period of time, the reason can be found in the shrinkage process. Leave it for a while, and if the glue still opens, it can be judged as a quality problem with the double-walled heat-shrinkable tube. Just purchase high-quality double-walled heat-shrinkable tube. A qualified double-walled heat-shrinkable tube should be as shown on the right side of the picture above, with a tight circle of hot-melt glue on the port. Adhesion, no glue opening, no glue spillage.

    Because the purchase price of heat shrinkable tube raw materials basically does not vary greatly, why are the prices of some brands so cheap? This involves the matching of formulas and the use of recycled materials for filling. It is difficult to find from the appearance that double-walled heat shrinkable tubes are very cheap. As an auxiliary material, shrink tube does not account for a large amount of money. If a quality accident occurs just because the quality of a small auxiliary material is not up to standard, the gain outweighs the loss. Therefore, you get what you pay for forever. When purchasing, try to choose the source manufacturer. The heat shrink tube manufacturer Duwai is the source manufacturer of double-wall heat shrink tubes. It has been producing double-wall heat shrink tubes for more than ten years. All the materials used are high-quality new materials. PVC materials have unstable adhesion. , specializes in R&D and production of PVC-specific stable bonding double-wall heat shrinkable tubes.