10.5 A Novel Co-Polymerizable Benzotriazole UVA for Polyurethane Dispersion
(Room 240-242)
10 Apr 18
4:30 PM
-
5:00 PM
Tracks:
Session 10: Polyurethanes II, Session 10: Protective Coatings
Polyurethane dispersion (PUD), has received more and more attention in coatings due to its water-borne nature and excellent overall properties. PUD’s are also the top selection for exterior coatings applications in consideration of weathering stability. PUD's weathering stability can be further enhanced by adding UV absorbers to the PUD to increase UV stability and provide long term durability.
Among UVA absorbers, benzotriazole (BZT) based UVA’s as shown below, provide the best protection on TPU against UV light. BZT UVA is manufactured in either a solid or liquid state. Solid BZT’s are not suitable for PUD resins as there is no melting step in the PUD coating process.
Liquid BZT UVA is easily formulated into the PUD coating if there is a pre-emulsifying process prior to addition. However, pre-emulsion can sometimes be difficult with a sophisticated challenging formulation. Liquid BZT UVA has another significant drawback: lowering of the Tg point of PU coating and subsequently reducing the hardness. Chitec is proud to report a new way to add a high performance BZT UVA into PUD system by using a novel Reactable BTZ UVA.
Figure (1) demonstrates a glycol functionality as shown below. This reactive UVA can be easily co-polymerized into the PUD back-bone by using a standard PUD preparation process, therefore eliminating the emulsion process.
Please note Figure #1 Chemical Backbone Diagram was not able to transfer to this form. It can be supplied via Word File if needed.
(Figure 1) Chiguard® 5530 Hydrophilic BZT
Testing in a PUD system containing 1% of Figure 3 - (fully reactable BZT UVA) was compared with a PUD system containing 1% of Figure 1 - (a hydrophilic BZT) and additional testing with Figure 2 - (a hydrophobic BZT). All products were tested with and without hindered amine light stabilizers. Figure 3 showed significant improvement of photopermance, haze, hardness, and adhesion under ASTM G-154.
Please note Figure #2 Chemical Backbone Diagram was not able to transfer to this form. It can be supplied via Word File if needed.
(Figure 2) Chiguard® 5582 Hydrophobic BZT
Please note Figure #3 Chemical Backbone Diagram was not able to transfer to this form. It can be supplied via Word File if needed.
(Figure 3) Chiguard® R-455 Fully Reactable BZT
In this paper, the process to prepare Figure 3 will be outlined along with the performance comparison against other BZT type chemistries. Global registration status will be also be presented.