PUR hot melt adhesive is a moisture-curing reactive polyurethane hot melt adhesive, primarily composed of isocyanate-terminated polyurethane prepolymer. It exhibits excellent bonding strength, temperature resistance, chemical corrosion resistance, and aging resistance. Being environmentally friendly and solvent-free, it is widely used in various fields such as packaging, wood processing, automotive, electronics, textiles, aerospace, and more.
Reaction mechanism: At room temperature, PUR hot melt adhesive is in a solid state, which melts into a fluid when heated, facilitating dispensing and coating. The two substrates are initially connected together through the PUR hot melt adhesive. After cooling, the adhesive layer condenses, and reacts with moisture in the air and on the surface of the substrate, extending the chain and generating a high-molecular polymer with high cohesion. This significantly improves the adhesive force, heat resistance, and weather resistance. Due to its high reactivity, it is widely used for bonding various substrates such as glass, metal, and plastic.
Usage method of PUR hot melt adhesive:
1. Storage conditions: The storage temperature for PUR hot melt adhesive is 8~22℃. It should be kept in a dark and dry place, avoiding excessive humidity. Do not use products with damaged packaging.
2. Before using PUR hot melt adhesive:
1) Before using PUR glue, it is necessary to check whether the vacuum packaging is intact. Do not use if there is any air leakage;
2) Preheating: Preheat the glue (typically for 15-20 minutes), with a recommended temperature range of 120-140℃;
3) After preheating, remove the glue residue from the top and end of the PUR glue hose before using the glue;
4) Remove substances that affect bonding, such as oil, dust, paint, release agents, and oxide layers, from the surface of the bonded area to ensure the surface of the bonded workpiece is dry.
3. Dispensing:
1) The temperature and air pressure during PUR hot melt adhesive dispensing may vary depending on the project. For specific details, please consult relevant technical personnel;
2) Stainless steel needles should be used as much as possible, with the inner diameter of the needle tip determined according to the specific project;
3) Before installing the needle nozzle, please discharge a small amount of glue to ensure that the PUR hot melt adhesive can be used normally;
4) The length of the needle tip exposed outside the heater should not exceed 3mm.
4. Assembly and press-fitting:
Apply PUR adhesive to the surface of the adherend at the application temperature; after determining the position of the adherend, press the two adherends together within the open time to complete the preliminary bonding.
5. Curing:
Store the initially bonded parts under suitable conditions for complete curing (the time for complete curing may vary depending on the amount of adhesive applied, environmental temperature, and environmental humidity).