Now that we’re in the middle of winter, it seems like an appropriate time to look at how low temperatures affect the performance of pressure-sensitive adhesives (PSAs).
A quick refresher: PSAs are the glue substance you would find on products like:
- Post-it notes
- Self-adhesive envelopes
- Price labels
Lastly, PSAs are visco-elastic polymers. This means they have both viscous and elastic properties.
When the temperature is high and low…
The common rule when it comes to high temperatures and visco-elastic materials is that less force is needed to actually stretch it.
However, when temperatures drop, it has an impact on the wetability of the PSA, which is its ability to completely contact and cover the two surfaces being bonded together.
Using the post-it note application, wetability means how much of the note will stick to another piece of paper and how well that portion will actually stick.
The colder the temperature, the more brittle the PSA becomes. As a result, it loses the ability to create stickiness and is actually prone to cracking.
Various PSAs perform differently at low temperatures
- Natural rubber-based adhesives are actually quite robust and can perform well at low temps
- Acrylic adhesives will work at low temperatures if they aren’t cross-linked or cured
- Hot melt PSA adhesives will perform better at lower temperatures vs a typical EVA hot melt
It’s also important to note that adhesive backing also plays a role in low-temperature performance:
- Backings which have not been plasticized will stiffen at lower temperatures
- Cloth backings retain their flexibility and effectiveness at very low temperatures
Something to remember when applying a PSA to a substrate
A good temperature range is between 59˚F (15˚C) to 95˚F (35˚C).
Why? Because the mixture of viscous and elastic properties in the pressure-sensitive adhesive is even balanced.
This ensures good wetability and can be applied not only to the tape but the substrate itself.
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