Polyester Polyol
Linear aliphatic chains terminated with hydroxyl groups provide the chemical basis for specialized polyurethane adhesives and coatings. A polycaprolactone diol is produced through the ring-opening polymerization of epsilon-caprolactone, resulting in a very uniform molecular weight distribution. This consistency leads to predictable viscosity and reaction rates when it is formulated into a laminating glue.
It offers a unique balance of low temperature flexibility and high mechanical strength compared to other polyester types.
Polymer Architecture
Melting points for these materials are relatively low, which aids in the processing of hot melt or solvent-free systems. Because a polycaprolactone diol has a highly crystalline nature, it provides excellent resistance to oils and greases that might otherwise penetrate a paper package. The absence of ether groups in its backbone makes it more stable against oxidation than polyether-based alternatives.
This stability is useful for medical packaging or high-end retail displays that require long-term color retention.
Adhesive Performance
Adhesive formulations using this polyol show superior adhesion to a wide variety of substrates including treated polyolefins and metals. While it is more expensive than standard adipate polyesters, the performance benefits in harsh environments justify its use in demanding converting applications. The resulting bonds are known for their high elongation and toughness.
