Polyurethane adhesives can be broadly classified into aliphatic and aromatic types based on the type of isocyanate used in their formulation. Here are some technical differences between aliphatic and aromatic polyurethane adhesives:
- Chemical Structure:
- Aliphatic Polyurethane Adhesives: These adhesives use aliphatic isocyanates in their formulation. Aliphatic isocyanates have open-chain structures. Aliphatic polyurethanes are known for their excellent UV stability and resistance to yellowing over time.
- Aromatic Polyurethane Adhesives: Aromatic polyurethanes use aromatic isocyanates, which have a cyclic structure with a benzene ring. Aromatic polyurethanes may be more prone to yellowing when exposed to UV light compared to aliphatic polyurethanes.
- UV Stability and Color Retention:
- Aliphatic Polyurethane Adhesives: Aliphatic polyurethanes are known for their superior UV stability. They resist yellowing and color change when exposed to sunlight or other UV sources, making them suitable for applications where color retention is critical.
- Aromatic Polyurethane Adhesives: Aromatic polyurethanes may experience some degree of yellowing when exposed to UV light over time. This can be a consideration in applications where aesthetics and color stability are important.
- Aliphatic Polyurethane Adhesives: Aliphatic polyurethanes are generally more flexible than aromatic polyurethanes. This flexibility can be advantageous in applications where some degree of movement or flexibility is required.
- Aromatic Polyurethane Adhesives: Aromatic polyurethanes tend to be more rigid compared to their aliphatic counterparts. They may be preferred in applications where a higher level of stiffness and structural strength is needed.
- Chemical Resistance:
- Aliphatic Polyurethane Adhesives: Aliphatic polyurethanes often exhibit good chemical resistance, making them suitable for applications where exposure to chemicals or solvents is a concern.
- Aromatic Polyurethane Adhesives: The chemical resistance of aromatic polyurethanes can vary depending on the specific formulation. Some aromatic polyurethanes offer excellent chemical resistance, while others may be more susceptible to certain chemicals.
- Aliphatic Polyurethane Adhesives: Aliphatic polyurethanes tend to be more expensive than aromatic polyurethanes. The cost difference is often a consideration in selecting the appropriate adhesive for a specific application.
- Cure Time and Processing Conditions:
- Aliphatic Polyurethane Adhesives: The cure time of aliphatic polyurethanes can vary, but they often cure relatively quickly. The curing process may be influenced by factors such as temperature and humidity.
- Aromatic Polyurethane Adhesives: Aromatic polyurethanes may have a range of cure times depending on the formulation. Some formulations may require longer curing times or specific curing conditions.
The choice between aliphatic and aromatic polyurethane adhesives depends on the specific requirements of the application, including factors such as UV stability, flexibility, chemical resistance, and cost. Manufacturers often consider these technical differences to ensure that the selected adhesive meets the performance criteria for a given application. Polytech has been producing binders for over 20 years. During this time, they have modified and changed their manufacturing processes based on real life feedback they get from their customers. This type of back-and-forth dialogue with their customers has led to having one of the best quality, and installer friendly products available for traditional pour-in-place projects, as well as their World Athletics approved Polytrak running track systems.