Hot Melt Adhesives: What They’re Made of, How They Work and Their Benefits

Hot melt adhesives are incredibly popular among manufacturers due to their versatility, good cost and  water and moisture resistance.

Let’s take a look at what hot melt adhesives are made of, how they work and some of their benefits:

What Are Hot Melt Adhesives Made Of?

Hot melt adhesives are thermoplastic, 100% solid and contain no solvents or water. They are comprised of three main elements:

  • Polymers: provide strength and flexibility and give the primary mechanical properties
  • Resins: provide wetting and adhesion properties
  • Plasticizer: controls the viscosity and enables it to be easily applied

How Do Hot Melt Adhesives Work?

Hot melt adhesives can bond similar and dissimilar materials. They are applied to an initial material when in a liquid or molten state. After a short open time, the second material is brought into contact. At this point, the adhesives cool down and set quickly, bonding the two together.

What to Consider When Applying Hot Melt Adhesives:

The following factors impact adhesive performance and should be considered when applying:

  • Temperature: The temperature must be hot enough so that the adhesive viscosity is low enough to adequately wet out the substrates and the materials can be assembled before cooling.
  • Add-on Level: The add-on level refers to the amount of adhesive used on a given application. This affects the adhesive wet-out to the secondary substrate by modifying the rate of cooling.
  • Compression: Compression is the amount of pressure applied to laminate the substrates and primarily affects the bond to the secondary substrate.
  • Open Time: The open time affects the adhesive temperature and wet-out.
  • Substrates: Substrate texture and chemistry affect adhesive bonding. Highly textured substrates allow for more mechanical adhesion. Highly surface energy substrates promote wet-out.

What Are Some Benefits to Using Hot Melt Adhesives?

From automotive and packaging to product assembly and pressure sensitive tapes and labels, hot melt adhesives have a range of applications. In addition to their versatility, hot melt adhesives offer the following benefits:

  • Long shelf life
  • Elimination of the curing step
  • No loss of thickness when solidifying
  • Little to no VOCs

For more information about hot melt adhesives, please call 800-7-BOSTIK.

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