How to choose hot melt adhesive

Hot melt adhesive is a kind of plastic adhesive. Its physical state changes with temperature within a certain temperature range, while its chemical properties remain unchanged. It is a non-toxic, odorless, and environmentally friendly chemical product.
Standards for judging the quality of hot melt adhesives:

1. Operating time. Fast operation is a characteristic of hot melt adhesives. The working time of hot melt adhesive is generally about 5 seconds. With the wide application of modern production methods-assembly lines, the working time requirements for hot melt adhesives are getting shorter and shorter, such as low pressure injection molding and packaging industry for hot melt adhesives. It is required to reach 1 second or less.
2. Resistance to temperature. Hot melt adhesives are sensitive to temperature. When the temperature reaches a certain level, the hot melt adhesive begins to soften. Below a certain temperature, the hot melt adhesive will become brittle. Therefore, when choosing a hot melt adhesive, you must fully consider the temperature changes in the environment where the product is located, instead of blindly choosing low-priced hot melt adhesives. This kind of hot melt adhesive will degumming and embrittlement under high temperature or low temperature environment.
3. Surface treatment of the substrate. The surface treatment of hot melt adhesive is not as strict as other adhesives, but the dust and oil on the surface of the adhered object should also be properly treated in order to make the hot melt adhesive play a better role in bonding.
4. The viscosity of hot melt adhesive is divided into early viscosity and late viscosity. Only when the early viscosity is consistent with the late viscosity can the hot melt adhesive and the substrate remain stable. In the production process of hot melt adhesive, it should be ensured that it has anti-oxidation, anti-halogen, anti-acid and alkaline and plasticizing properties. Depending on the material to be bonded, the viscosity of the hot melt adhesive is also different. Therefore, different hot melt adhesives should be selected according to different materials.
5. With good performance, the melt viscosity changes greatly when the temperature changes. Hot melt adhesives can maintain good permeability only if they have a suitable melt viscosity.