Differences Between PUR Hot Melt Glue Machines and Conventional Hot Melt Glue Machines

PUR stands for moisture-curing reactive polyurethane hot melt adhesive. Its primary component is an end-isocyanate polyurethane prepolymer. PUR adhesives possess polar and chemically reactive urethane or isocyanate groups in their molecular structure. They exhibit excellent bonding strength with materials containing active hydrogen, such as porous substrates like wood, leather, textiles, paper, and ceramics, as well as smooth-surfaced materials including plastics, metals, glass, and rubber. Under conditions that inhibit chemical reactions, PUR hot melt adhesive is heated to melt into a fluid for coating application. When two substrates are pressed together and cooled, the adhesive layer solidifies to provide bonding. Subsequently, it reacts with moisture present in the air and on the substrate surfaces, undergoing chain extension to form a high-molecular-weight polymer with enhanced cohesive strength. This process significantly improves bonding strength, heat resistance, and low-temperature performance.

The scope of hot melt adhesives is quite broad. Most hot melts are heat-activated, allowing for re-heating after bonding, making them reversible. PUR, however, is a moisture-curing hot melt adhesive. It is heat-activated and reacts with moisture in the air after bonding. Once cured, it becomes irreversible (meaning it will not melt even when heated). Therefore, PUR is characterized by high cohesive strength and strong bonding strength. They exhibit superior resistance to both high and low temperatures, significantly outperforming conventional hot melt adhesives.

Furthermore, the key distinctions among PUR hot melt adhesive equipment lie in the specific machinery used, storage conditions, and sealing methods. When operating PUR hot melt adhesive machines, ensure no rapid airflow is present. The adhesive drum storage and all piping systems must be sealed to prevent air exposure. Otherwise, the PUR inside the drum will react with moisture in the air, resulting in energy waste. Additionally, PUR packaging varies-including aluminum foil vacuum bags, drum containers, and bulk filling formats-each requiring different equipment configurations.