Learn more about the relationship between surfaces and adhesives. A guide to choosing the best adhesive for any surface.

1. Our guide to choosing the best
adhesive for any surface
WHAT MAKES A
LABEL STICK?

2. WHEN LABELING, THE SURFACE
MAKES ALL THE DIFFERENCE...

3. We talk about polar surfaces like metal
and glass, and non-polar surfaces like
PE and PP plastic.
TWO SURFACE TYPES

4. When atoms bond together
as molecules, they often share
electrons unequally – this creates
an electric dipole.
More dipoles mean greater
polarity or surface energy.
WHAT DETERMINES
POLARITY?

5. We measure surface-energy in dynes/cm.
Low-energy surfaces make it harder to
achieve good adhesive wet-out.
MEASURING
SURFACE ENERGY
TYPICAL SURFACE ENERGIES
(dynes/cm)
High-energy polar surfaces
Aluminium 840, Glass 250-500,
Stainless steel 700-1000
Low-energy non-polar surfaces
Acrylic 38, Polyethylene (PE) 31,
Polypropylene (PP) 29

6. Wet-out is a measure of how well an adhesive flows over a
surface. Successful wet-out occurs when the surface has a
higher attraction to the adhesive than the adhesive has to itself.
WHAT IS WET-OUT?

7. GOOD ADHESIVES NEED BALANCE
Getting optimal adhesion requires an adhesive
with an appropriate balance of stickiness (tack
and peel) and sufficiently low surface energy
relative to the surface to be labelled.

8. Adhesives can be modified for optimal
adhesion to high- or low-energy
surfaces. The adhesives we use also
resist heat, water, UV light, and are
environmentally friendly.
ENGINEERING ADHESIVES

9. MODIFICATION DEPENDS
ON THE SURFACE
Labels for high-energy surfaces like glass require
little adhesive modification.
Labels for low-energy surfaces like PE plastic
require more adhesive modification, such as
additional tackifiers and additives.

10. BUT IT’S NOT THAT SIMPLE...
The additives that lower the surface
energy of adhesives for PE plastic also
reduce cohesion.
Cohesion describes the internal
strength of an adhesive – or how
resistant they are to chemicals, oils,
heat, and exposure to water.

11. To regain the internal strength (cohesion)
we lose from using additives, we cross-link
the polymers in the adhesive.
This locks the polymers together, increasing
the adhesive’s resistance to heat, chemicals,
UV-light, and water.
CROSS-LINKING
INCREASES COHESION
Before
After

12. UV light starts a cross-linking reaction in our RC adhesives.
Our RX adhesives are catalyst activated. This results in an
exceptionally high density of cross-links, which increases
resistance to chemicals, UV light, and temperature.
UV AND CATALYST-ACTIVATED
CROSS-LINKING

13. So what does this all mean when
choosing an adhesive?

14. Durable labels require long-term resistance to heat,
oils, chemicals, and mechanical stress.
That means cross-linking technology is a good choice
to improve adhesive strength even when labeling a
high-energy surface like metal or glass.
ADHESIVES FOR
POLAR SURFACES

15. Non-polar surfaces like PE and PP plastic
demand a more complex formulation
(additives, tackifiers, and cross-linking)
to ensure good bonding.
ADHESIVES FOR
NON-POLAR SURFACES

16. UPM Raflatac offers the optimal adhesive for
your labeling needs, whatever the surface.
Check www.upmraflatac.com or
contact us for more information.
WE CAN HELP YOU
MAKE THE BEST CHOICE