The inner layer of double-wall heat shrinkable casing is a layer of hot melt adhesive. The hot melt adhesive is made by copolymerization of ethylene and vinyl acetate under high pressure. The hot melt adhesive is made by adding tackifier, viscosity regulator and antioxidant. Hot melt adhesives are solventless, water-free, 100% solid fusible polymers. They are solids at room temperature. They melt to a certain extent and become liquid adhesives that can flow and have a certain viscosity. After melting, they become light brown translucent or original white.
Hot melt adhesives have the following characteristics:
1. Curability, usually solid at room temperature, melts into liquid when heated to a certain extent, and quickly becomes solid once cooled below the melting point. When in use, as long as the hot melt adhesive is heated and melted into the required liquid, and smeared on the bonded object, the bonding and solidification can be completed in a few seconds after pressing, and the degree of hardening, cooling and drying can be achieved in a few minutes.
2. Re-viscous, heat-shrinkable tube glue smeared on the adhesive after cooling and curing, can also be re-heated and melted, re-turned into adhesive and then bonded with the adhesive, which has a certain degree of re-viscous;
3. Strength and toughness, with fast curing, low pollution, strong adhesion, both a certain degree of flexibility, hardness, and a certain degree of toughness.
According to the above, it can be further known that the double-wall heat-shrinkable tube has better waterproof and stronger insulation than the ordinary single-wall heat-shrinkable tube, so the double-wall heat-shrinkable tube is more and more widely used.