A Study of Polycaprolactone Technologies for Reactive Hot Melt Adhesives
In reactive hot melt adhesives, polycaprolactone polyols are commonly diols of molecular weight between 2,000 and 4,000 and are used in the soft segments of the polyurethane structure. In addition to polycaprolactone polyols, polycaprolactone thermoplastics are used to enhance the performance of the adhesive. The polycaprolactone thermoplastics provide increased green strength to the adhesive and are used in combination with polyurethane pre-polymers.
As market drivers accelerate the adoption of polyurethane reactive hot melt adhesives away from solvent-borne solutions, the use of polycaprolactone technology in reactive hot melt adhesive applications is examined.
A study conducted at Ingevity’s new Innovation Centre in Warrington, UK, has fully characterized the performance of a 4,000 MWt caprolactone diol versus that of a commercially available polyester diol.
Reactive hot melt adhesives provide advantages in a variety of end-application areas that include textiles, woodworking, construction, automotive, bookbinding, and electronics. A combination of the initial recrystallisation after application with the subsequent polyurethane polymerization gives this type of adhesive platform superior adhesion properties with enhanced chemical and heat resistance compared to traditional non-reactive hot melt adhesives.
Polycaprolactone is polymerized via a ring opening synthesis route, where caprolactone monomer is ring-opened via an initiator moiety. The initiator moiety is a hydroxyl functionalized molecule, which can be a diol, triol, or tetrol…
Source: Ingevity/Adhesives Magazine