The selection of hot melt adhesive film should carefully consider the following factors:
Since the material to adhere to has specific requirements for colour, the colour requirements for the hot melt adhesive film should also be different. If there is no special requirement for the material's colour to adhere to, just use ordinary hot melt adhesive film.
2. Surface treatment of the material to be bonded.
For the surface treatment of the material to be bonded, the hot melt adhesive film is not as strict as other adhesives, but the dust and oil stains on the contact surface should also be properly treated to achieve a better bonding effect.
3. Curing time
High bonding efficiency is the most important feature of hot melt adhesive film. Usually, the operation time of the hot melt adhesive film is about 15 seconds, but with the popularization of modern assembly lines, the machine speed is getting faster and faster, so the curing time of the hot melt adhesive film has also put forward higher requirements. In some applications, the curing time of the hot melt adhesive film is required to reach about 5 seconds.
4. Temperature resistance
Hot melt adhesive films are very sensitive to temperature. As the temperature increases, the hot-melt adhesive film begins to soften. When the temperature is lower than the glass transition temperature of the adhesive film, the hot-melt adhesive film becomes brittle again. Therefore, the selection of the hot-melt adhesive film should fully consider the environment where the product is located—temperature changes.
5. Initial tack and bond strength
All adhesives have the concept of initial tack, and hot melt adhesive films are no exception. Having a good initial tack can keep the bonded objects in a relatively stable state at the beginning of contact. The bonding strength of the hot melt adhesive film is related to the raw materials used in production and the material of the adherend. The material of the adherend is different, and the material of the hot melt adhesive film required should also be different; otherwise, it will affect the final bonding strength. It should be noted that initial tack and final bond strength are not much related; they are two different concepts.