TROUBLESHOOTING TIPS: ADDRESS HOT MELT ADHESIVE POOR SUBSTRATE ADHESION AND SHORT OPEN TIME

While hot melt adhesives are suitable for a range of markets and applications, they are prone to certain issues that require hot melt adhesive troubleshooting. Common problems include:

• Charring and stringing
• Pop opens
• Pre-set and slow set

In recent blogs, we’ve discussed these issues and how to decrease their likelihood. Now, let’s take a look at poor substrate adhesion and short open time and how to address it.

Poor Substrate Adhesion

The following issues can trigger poor substrate adhesion:

• Improper wet-out on the secondary surface: adhesive shows that the glue film is mostly on just one surface
• Bond disruption during setting stage: adhesive on both surfaces has leggy strings

As a result, bond failure occurs when there is poor substrate adhesion.

However, this issue can be addressed in the following ways:

• Apply heavier glue film, or raise the application temperature. Both may be necessary at times.
• If using conductive surfaces, such as metals, the substrate may have to be preheated to ensure wet-out onto the secondary surface.
• Check the compression to ensure there was no shifting during adhesive set up.
• Use a faster setting product, or anticipate a longer compression time.
• Apply the adhesive at a cooler temperature.

Short Open Time

An adhesive’s open time is the time it takes for an applied adhesive to form a solidified bond. If an adhesive’s open time is too short for a given application, it may be unable to form a successful bond. Ways to resolve this issue include:

• Increase application temperature
• Increase amount of adhesive used
• Preheat the substrates

For more hot melt adhesive troubleshooting tips, call 800-7-BOSTIK.