Hot melt adhesives (HMAs) constitute a broad category, with PUR being one of its types. Most HMAs are heated for application and can be reused after bonding, making them reversible. In contrast, PUR is a moisture-reactive HMA that, once heated and bonded, reacts with moisture in the air, rendering it irreversible (i.e., it does not melt even upon heating). Therefore, PUR exhibits superior resistance to both high and low temperatures.
PUR hot melt adhesive
PUR (Polyurethane Reactive), whose full Chinese name is moisture-curing reactive polyurethane hot melt adhesive, primarily consists of isocyanate-terminated polyurethane prepolymer. The adhesion and toughness (elasticity) of PUR can be adjusted, and it exhibits excellent bonding strength, temperature resistance, chemical corrosion resistance, and aging resistance. In recent years, it has become one of the important varieties in the adhesive industry. It is now widely used in various national economic sectors such as packaging, wood processing, automotive, textile, electromechanical, aerospace, and more
PUR adhesive contains polar and chemically reactive urethane groups (-NHCOO-) or isocyanate groups (-NCO) in its molecular structure, which exhibit excellent adhesive strength to materials containing active hydrogen, such as porous materials like wood, leather, fabric, paper, ceramics, as well as to surface-smooth materials like plastics, metals, glass, and rubber
Compared to EVA hot melt adhesives and water-based solvent adhesives, PUR has the following advantages:
1. Solvent-free, one-liquid type. Unlike solvent-based adhesives, which require a drying process, it eliminates environmental pollution and poisoning issues caused by the presence of solvents, meeting environmental protection requirements. The bonding process is simple, and adhesive application methods such as roller coating or spraying can be used
2. Good operability. The two adhering bodies can be fixed in a short time, allowing for the rapid transfer of the assembly parts to the next processing step, thereby improving work efficiency
3. It exhibits excellent resistance to heat, cold, water vapor, chemicals, and solvents. Compared to traditional hot-melt adhesives, the cross-linked structure of reactive hot-melt adhesives significantly enhances the listed properties as well as bonding strength