Temperature and process of using hot melt glue system
Temperature is an indispensable factor in the process of using hot melt adhesives. Temperature changes the physical state of the glue from a solid to a liquid state. Therefore, it can be easily applied to the surface of the material. However, the proper temperature requires control and a basic understanding of the optimum temperature for the application as well as its negative effects of overheating in using hot adhesives.
Each type of adhesive usually has an optimal operating temperature range, within that optimal temperature range, the adhesive ensures the ability to adhere two material surfaces together. When trying to control the temperature of the device so that the viscosity can meet the application, but that temperature is not within the good working range of the adhesive, it will lead to a decrease in adhesion.
- Low-temperature heating adjustment in order to increase the glue viscosity can prevent the polymer and wax molecules from wetting the surface of the material and that can cause the inability to form the desired bond between the surfaces material.
- High-temperature control to reduce the viscosity of the glue. This can extend beyond the upper range of the working area of the adhesive. The higher the temperature, the faster the oxidation will lead to the loss of the glue quality.
Oxidation occurs when the presence of free radicals due to poorly stable bonds that are degraded by heat. Free radicals in the environment exposed to air induce propagation reactions and gradually destroy the bonds in the polymer structures of the adhesive molecule. The easiest to observe the case is that the glue has a darker color and creates coal slag on the wall and bottom of the heater tank. Prolonged use can cause pipe and nozzle clogging.
To limit this process from happening, in the process of using a new glue, you can add new glue regularly, which will cause the surface layer to cool down when exposed to the air, leading to reduced oxidation.
A heating tank is a part with a high possibility of exposure to the air so that the temperature of the tube and nozzle can be adjusted higher than the tank to both use the glue and limit the oxidation of the glue. In addition, some hot melt glue systems incorporate a vacuum system or nitrogen gas system to slow down the oxidation adhesive.
Regular cleaning of glue system includes glue tank, glue hose, and nozzle periodically to remove the dust formed by using process. Using suitable cleaning solutions to achieve high efficiency.
In short, we should use suitable glue for each of the applications. Do not use the adhesive at temperatures over the supplier's standards and limit open the lid of the tank when not needed.