Characteristics of EVA Hot Melt Adhesives
EVA hot melt adhesive is a solid meltable polymer that does not require solvents and does not contain 100% moisture. It is a solid at room temperature, and it becomes a fluid and viscous liquid when heated to a certain temperature. The melted EVA hot melt adhesive is light brown or white.
EVA hot melt adhesive is composed of basic resin, tackifier, viscosity modifier and antioxidant.
#1 The color of the glue.
If there is no special requirement on the color of the substrate itself, it is recommended to use yellow EVA hot melt adhesive. Generally speaking, yellow EVA hot melt adhesive is more viscous than white.
#2 Surface treatment of the substrate.
The surface treatment of EVA hot melt adhesive is not as strict as other adhesives, but the dust and oil on the surface of the substrate should also be properly treated to make the EVA hot melt adhesive play a better role in bonding.
#3 Operation time.
Fast operation is a major feature of EVA hot melt adhesive. The working time of EVA hot melt adhesive is generally about 15 seconds. With the wide application of modern production methods-assembly lines, the working time requirements for EVA hot melt adhesives are getting shorter and shorter, such as book binding and speaker manufacturing. The operating time required to reach about 5 seconds.
#4 Resistance to temperature.
EVA hot melt adhesive is more sensitive to temperature. When the temperature reaches a certain level, the EVA hot-melt adhesive begins to soften. Below a certain temperature, the EVA hot melt adhesive will become brittle. The choice of EVA hot-melt adhesive must fully consider the temperature change of the environment where the product is located.
The viscosity of EVA hot melt adhesive is divided into early viscosity and late viscosity. Only when the early viscosity is consistent with the late viscosity can the EVA hot melt adhesive and the substrate remain stable. In the production process of EVA hot melt adhesive, it should be ensured that it has resistance to oxidation, halogen resistance, acid and alkali resistance and plasticity. Depending on the material to be bonded, the viscosity of EVA hot melt adhesive is also different. Different EVA hot melt adhesives should be selected according to different materials.