The components of hot melt adhesives
Hot melt adhesives consist primarily of three components:
- a polymer
- an adhesive resin
- a wax or oil
A polymer forms the backbone of the adhesive and gives the hot melt its strength and flexibility. These properties are largely determined by the type of polymer, the molecular weight and the volume. A high polymer content creates high viscosity and flexibility. A lower polymer content means less viscosity. Polymers often used for hot melt adhesives include TR, EVA, APAO, PUR and PA. Sometimes, other additives are added in order to influence specific properties. For example, oil or wax are used to adjust the viscosity and
open time. Resins provide for the
initial tack and bonding.