RAHN offers a family of resins that can be used to formulate UV PSAs. An overview of these materials is provided in our Lab Report on Pressure Sensitive Adhesives. This report also offers starting point formulations. When developing a UV PSA, optimizing performance depends on more than just the composition. Film thickness and curing conditions can have a dramatic effect on properties.
The Best Cure
Lamp selection and intensity will make a difference in cured film properties. To see how both the type of lamp and lamp intensity influence peel strength, we cured our
Starting Point Formulation #137 using different bulb types, power settings (WPI) and intensity. As you can see from the data below, with the standard Hg bulb when dosage is constant, but intensity increases, peel strength goes up. However, even at higher intensity, the D bulb is not as effective as the Hg bulb when used with this specific formulation.
| Formula |
Bulb
type |
Film
thickness |
WPI |
Dose
mJ/cm2
(UVA) |
Dose
mJ/cm2
(Total) |
Intensity*
mW/cm2 |
Peel
lbf/in |
| SPF 137 |
Hg |
1.0 mil |
300 |
609 |
1326 |
1276 |
3.6 |
| SPF 137 |
Hg |
1.0 mil |
400 |
280 |
692 |
1607 |
3.6 |
| SPF 137 |
Hg |
1.0 mil |
400 |
609 |
1366 |
1680 |
5.1 |
| SPF 137 |
D |
1.0 mil |
400 |
609 |
1436 |
1932 |
4.1 |
* Intensity refers to total lamp output across the entire electromagnetic spectrum.
mW/cm2 x seconds = mJ/cm2 |
Sometimes Less is More
It is also important to consider film thickness. Altering the composition can change the cured film thickness required for optimum performance. As illustrated below, when curing conditions remain the same, peel strength may be increased by increasing the film thickness . . .
| Formula |
Film
thickness |
WPI |
Dose
mJ/cm2
(UVA) |
Dose
mJ/cm2
(Total) |
Intensity
mW/cm2 |
Peel
lbf/in |
| SPF 137 |
1.0 mil |
400 |
609 |
1366 |
1680 |
5.1 |
| SPF 137 |
2.0 mil |
400 |
609 |
1366 |
1680 |
5.1 |
| SPF 137 |
3.0 mil |
400 |
609 |
1366 |
1680 |
6.3 |
. . . or by decreasing the film thickness.
| Formula |
Film
thickness |
WPI |
Dose
mJ/cm2
(UVA) |
Dose
mJ/cm2
(Total) |
Intensity
mW/cm2 |
Peel
lbf/in |
| US14004-H |
1.0 mil |
400 |
480 |
1172 |
1647 |
6.3 |
| US14004-H |
2.0 mil |
400 |
480 |
1172 |
1647 |
6.0 |
| US14004-H |
3.0 mil |
400 |
480 |
1172 |
1647 |
5.8 |
Through careful selection of materials, application methods and curing conditions, you can design a wide range of UV pressure sensitive adhesives. Whatever your requirements, RAHN can provide the materials and expertise to help you achieve your goals.
For more information or to order samples visit our
web site or contact your local RAHN USA representative:
RAHN USA will be closed on Monday, May 25, 2015.
