Hot Melt Adhesive information
Complete information on hot-melt adhesives.
Hot-melt adhesive is a thermoplastic material that is solid at room temperature but which, when applied in liquid (melted) state, sticks to a surface as soon as it cools below its melting point.
There are other types of frequently used non-melting adhesives such as water-based or solvent-based adhesives and cold-applied reactive adhesives.
The main advantages of hot melt compared with these adhesives can be summarised in the following points:
- As they are solid they are easier to handle, store and transport.
- Their bonding strength is instant, without drying or curing.
- They do not need time for holding the bond.
- Their high viscosity compared with other adhesives allows them to be used on porous and non-porous surfaces.
- High performance, faster production.
- High performance of the glued bond. Mechanical strength, tolerance against chemical aggression, extreme temperatures, etc.
- Reusable in most cases.
There are countless applications of hot melt in diverse markets, most importantly:
- Graphic arts
- Automotive industry
- Wood and furniture
- Sanitary products
- Tobacco Packaging
Adhesives can be classified in various ways considering the different features that define them. Adhesives for cold and hot (hot melt) application; reactive and non-reactive adhesives; within the hot-melt adhesives, according to their polymer base: EVA, polyolefin, polyurethane, polyamide, etc.
From the point of view of the application system, there are two main groups of hot-melt adhesives:
- Thermoplastic adhesives (EVA, PSA, PO)
- Reactive adhesives (after a reactive curing process, such as PUR, POR, PA).
The former are characterised by a kind of physical adherence, while the latter involve a chemical adherence that occurs during the solidification or curing process.