A reactive hot melt adhesive is any thermoplastic adhesive or sealant that can be applied at elevated temperatures as a liquid melt, cools to become a solid at room temperature, and then subsequently reacts to become a thermosetting polymer with enhanced physical properties. Hot melt adhesives can be made to be reactive in several ways.
Reactive hot melt adhesives have been available since the 1980s. Due to their thermoplastic nature during application, they have many of the desirable processing characteristics of conventional hot melts, such as no solvents present, no mixing requirements, and immediate green strength. Although conventional, nonreactive hot melt adhesives (e.g., ethylene vinyl acetate, polyalphaolefin, polyester, and polyamide) are widely used in many industrial applications, they have certain performance limitations, such as poor heat resistance, water or solvent permeation, and creep. These limitations generally prevent their use in many critical or structural bonding applications.