WHAT EFFECTS DO TEMPERATURE CHANGE HAVE ON HOT MELT GLUE?
The molten adhesive is composed of a thermoplastic material. At normal temperature, the glue is solid, but when it is affected by increasing temperature, it will flow softly and reach a liquid state at a high temperature. After being applied to the surface of the material, the adhesive will lose heat and return to a solid-state.
This shows that temperature is a factor that directly affects the viscosity, elasticity, ductility/stiffness, adhesion, and usage of hot melt glue.
Next, let us analyze the link between temperature and hot melt glue to be able to apply hot melt glue effectively and ensure the highest safety.
1. Influence on adhesion strength
Different types of molten adhesives will have varying degrees of temperature resistance, but in principle, when the temperature rises, the strength of the molten adhesive decreases as it loses its ability to hold onto two surfaces of materials connected together.
On the other hand, low temperatures often do not adversely affect the durability of adhesives. Normally, they will make the glue become harder and less flexible.
2. Influence on hardness, thermal stability, and safety
For hot melt glue, after applying to the surface of the material and returning to a solid-state, the glue actually promotes its adhesion.
However, the hardness of the glue is affected by the temperature. The high temperature will reduce the hardness or durability of the glue. If the glue is too loose when pasting, it will cause the glue to spill out of the bond and therefore cause aesthetic loss to the finished product and may even cause burns during operation.
Thermal stability: when the glue is heated above the normal operating temperature, the chemical structure will be broken or changed, lead to reduce the elasticity of the bond. This also leads to crack or breakage and loss of inherent adhesion. This is also known as thermal degradation. Therefore, it is necessary to understand and apply the specifications of the glue exactly so that it can be used appropriately and effectively on the equipment line at the factory.
Safety issues: the glue is used in molten state, this requires operators to be fully equipped with necessary protective equipment and trained in basic production safety procedures to prevent and minimize unintended injuries or accidents.
3. The effects of temperature on viscosity
Viscosity is the ability to resist flow resistance. The higher the temperature acting on the adhesive, the lower the viscosity of the adhesive (liquid).
If the adhesive is too loose (high temperature), it will be difficult to fix the bond on the paste surface, the glue can also overflow the edge and cause burns and the drying time is slow. For the purpose of positioning, we should use glue that has moderate or high viscosity (to help fast fixation).
If the adhesive is used at very high viscosity (low temperature), the glue will quickly dry before it can adhere to the second material surface, lead to reduce adhesion effect. In addition, with too low operating temperatures, the operation will be slowed down, lead to reduce production efficiency.
Recommended solution: Using the glue which has viscosity and operating temperature is suitable for the speed of the production line to maximize productivity.
If you are not sure that the glue is appropriate and standard with the production line, please contact us for advice and solutions to solve the problems.