Traditional hot melt adhesives (also known as thermoplastic adhesives) are one hundred percent solid, except when heated above a temperature of between 160°C and 180°C. The substance rapidly cools and sets, creating a quick and strong bond. The adhesives can be either very rigid or soft and pliable, depending on what the material is composed of. Hot melt adhesives are compounded from thermoplastic polymers and plastics. They are not affected by moisture, water, or humidity, unlike many other bonding agents.
Hot melts are prominently used in the markets of automated manufacturing lines, packaging, converting, footwear, product assembly, bookbinding, and many more. The materials used to make up the hot melt adhesive usually depend on what purpose it will serve. Unlike solvent and water-based adhesives, there is no drying time with hot melt, so its uses are expanding rapidly. Recently there has been new development in the area of low-temperature hot melts. These hot melt adhesives bond at considerably lower temperatures ranging from 120°C to 130°C. The reduction in heat results in longer lasting hot melt equipment.