Hot melt adhesive mesh film needs to be heated before bonding, so heating temperature is a necessary condition. However, many manufacturers use the method of increasing machine temperature and shortening hot pressing time to improve production efficiency in actual use, which can cause excessive melting of the adhesive, excessive penetration into the inside of the adhesive, and even adhesive penetration, resulting in poor bonding or foaming problems. When the temperature is too low, the hot melt adhesive mesh film cannot be fully melted, and naturally cannot play a good bonding role.
This type of temperature control problem can be solved by using an infrared thermometer to measure the temperature of the mechanical surface, thereby achieving better temperature control effects
The same principle applies to the hot pressing time, which cannot be too short or too long. It should be adjusted according to the specific parameters of the hot melt adhesive film and the appropriate time should be selected. Excessive melting of the adhesive over a long period of time, and insufficient melting of the adhesive in a short period of time can lead to poor adhesion.
4. Pay attention to some special properties of the adhesive itself
If some materials have a high moisture content, there will be a problem of water vapor during the hot pressing process. Under pressure, water vapor cannot be released well, forming bubbles and leading to poor adhesion. At this point, it may be necessary to adopt a segmented pressurization method during the composite process, release the pressure appropriately at a specific time period, remove the bubbles, and then repeat the pressurization.
If some materials themselves are not very flat or there is a certain degree of thermal stress during hot pressing, then there will be a certain degree of rebound after pressure relief. However, hot melt adhesive needs to wait for the adhesive to cool and harden before forming adhesive strength. Therefore, once rebound occurs, the adhesive has not cooled and hardened yet, which naturally leads to poor adhesion. At this point, it is necessary to add a cold pressing step after hot pressing to quickly cool the hot melt adhesive and form a better adhesive strength.
So when using the hot melt adhesive film, you can refer to the process parameters recommended by the manufacturer and adjust the parameters according to your own actual situation under the guidance of the hot melt adhesive film manufacturer. This is the correct approach.
