Coatings World - August 2016

New Advances in UV-Curable Soft-Touch Coatings

concentration of crosslinker M1 (Figure 2). While UA6 and UA7 both create a rubbery coating with 10% crosslinker on resin, UA6 has several advantages over UA7. First, we achieve a feel with more grip (velvety) using UA6 without the need to decrease the crosslinker as much. The ability to use higher levels of crosslinker is advantageous as it allows for higher crosslink density and better coating durability. In addition, UA6 had a better overall feel quality than blends with UA7 (not shown in figures). While we were able to achieve a rubbery feel at 90% urethane oligomer UA6 and 10% crosslinker (M1), the films did not have the desired durability. When we increased the level of crosslinker (M1) to 17.5%, we were able to achieve a rubbery coating with improved properties over the previous rubbery coating that contained 10% crosslinker (Figure 3).

In our second approach we attempted to create a soft touch coating with an existing trifunctional acrylate crosslinker and low functional acrylate monomers (AM) as the soft connecting segments instead of difunctional urethane acrylates. Formulations with the existing crosslinkers and monomer (AM1) did not achieve the desired combination of feel and properties (Table 3). Formulating newly designed crosslinker, M6, with acrylate monomer, AM1, at 60: 40 crosslinker to acrylate monomer, resulted in both good feel and good durability, as seen in Table 4, formulation 53. After varying the monomer formulated with M6 to screen for improved feel and durability, we found M6 with AM5 had the best velvety feel of all our previously tested formulations (Table 4) along with good durability.

Conclusions

Newly designed oligomer UA6 and cross-
linker M6 allow us to create UV-curable
soft-feel coatings with a range of haptic
sensations (Figure 4). These new products
show improved durability over the indus-
try standard two-part urethane coating
tested and exhibit little to no decrease in
soft-touch feel quality. In addition to en-
hanced durability, the UV-curable systems
have infinite pot life, short cure times and
no free isocyanate. Current work focuses
on 100% UV-curable and waterborne
UV-PUD to provide low-VOC options to
formulators and convertors. CW

References

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2. May, A.C.; Stewart, J.L.; Tapert, S.F.; Paulus, M.P. The effect of age on neural processing of pleasant soft touch stimuli.

Frontiers in Behavioral Neuroscience 2014, 8, 52.

3. Essick, G. K.; McGlone, F.; Dancer, C.; Fabricant, D.; Ragin, Y.; Phillips, N.; Jones, T.; Guest, S. Quantitative assessment of pleasant touch. Neurosciences and Biobehavioral Reviews 2010, 34, 192-203. 4. Drujon, X.; Spagnola, L.; Moeller G. Most Recent Developments in UV-Curable Soft-Touch Coatings. UV and EB Technology 2016, 4, 18.