Polyurethane adhesives possess a variety of unique properties, which enable them to perform exceptionally well in different industrial applications:
1. Outstanding shear and impact resistance: suitable for various scenarios requiring structural bonding.
2. Excellent flexibility and buffering, shock-absorbing functions: capable of flexibly adapting to different substrates with varying thermal expansion coefficients.
3. Extraordinary low-temperature and ultra-low-temperature performance: can maintain excellent bonding effects even in extremely cold environments, far superior to other types of adhesives.
4. Low VOC content and environmental-friendly characteristics: low volatile organic compounds, environmentally friendly and safe, non-flammable.
5. Excellent resistance to chemicals and abrasion: suitable for bonding requirements of various materials.
These properties enable polyurethane adhesives to meet the demands for high strength and environmental adaptability.
The Shortcomings and Improvements of Polyurethane Adhesives
Although polyurethane adhesives have demonstrated excellent bonding performance in various fields, they also have some drawbacks:
1. Disadvantages and Challenges
Some types of polyurethane adhesives may be highly sensitive to changes in environmental humidity and temperature, which to some extent limits their application scope.
2. Toxicity issue
During the application process of polyurethane adhesives, some volatile organic compounds may be released. These compounds have a certain degree of toxicity. Although many polyurethane adhesives have been improved to reduce toxicity, in some cases, ventilation and safety measures during use still need to be paid attention to.
3. Longer curing time
During the process of preparing low-toxicity polyurethane adhesives, a series of chemical reactions are required. One crucial step involves the reaction between end-hydroxyl polyfunctional epoxides and end-isocyanate-based polyurethane prepolymer to introduce epoxy groups. However, this process requires a relatively long time to complete the curing, ensuring the thoroughness of the reaction and the stability of the product.
4. Insufficient high-temperature resistance
Polyurethane adhesives exhibit poor heat resistance in high-temperature environments, which limits their application scope. Researchers are exploring ways to enhance their high-temperature resistance through material modification and other methods.
