The development history of polyurethane adhesives is a history of continuous innovation, adaptation to demands and expansion of application boundaries.
Its story began in the 1930s. With the foundation of polyurethane chemistry, scientists successfully synthesized polyurethane materials. However, it was not until the 1950s that early forms of polyurethane adhesives with practical value emerged. During this period, people mainly utilized the activity of isocyanates to develop polyisocyanate-based adhesives for bonding rubber and metal, solving the problem of high-strength elastic bonding.
The 1960s and 1970s marked the first period of rapid development for polyurethane adhesives. The key breakthroughs were the emergence of thermoplastic polyurethane elastomers and the commercialization of solvent-based polyurethane adhesives. This type of adhesive features excellent toughness, flex resistance and bonding performance, and has begun to be widely used in fields such as shoe-making, packaging (especially flexible packaging lamination) and textile lamination. They can bond a variety of different materials very well, demonstrating the potential of "all-purpose glue".
In the 1980s and 1990s, the driving force of development shifted towards environmental protection and technological innovation. With the awakening of global environmental awareness, the problem of volatile organic compounds in solvent-based adhesives has become increasingly prominent. As a result, waterborne polyurethane adhesives and solvent-free polyurethane adhesives (including reactive hot melt adhesives) have become research hotspots. The water-based system uses water as the dispersion medium, significantly reducing VOC emissions. Solvent-free systems, on the other hand, achieve environmental friendliness, high efficiency and energy conservation through a 100% solid content, and are particularly favored in food packaging and high-speed composite production lines.
Since the beginning of the 21st century, the development of polyurethane adhesives has been advancing in depth towards high performance, functionalization and greenness. To meet the demands of high-end manufacturing industries such as new energy vehicles, electronic appliances, and aerospace, special polyurethane adhesives with high-temperature resistance, flame retardancy, heat conduction, and electrical conductivity have emerged. Meanwhile, bio-based polyurethane adhesives use renewable resources (such as vegetable oil) as raw materials, responding to the call for sustainable development. In addition, the application of new curing technologies such as ultraviolet curing and moisture curing has further enhanced the convenience of construction and curing efficiency.
In conclusion, polyurethane adhesives have evolved from the initial specialized adhesives through several technological waves such as solvent-based, water-based, and solvent-free ones, and have now grown into an important adhesive variety that combines excellent comprehensive performance with good environmental compatibility. Its development process perfectly reflects the intrinsic driving force of the chemical industry to keep pace with The Times and continuously meet the new demands of society.
