Catalysis of the Isocyanate-Hydroxyl Reactions ... - Wernerblank.com

Components A and B were mixed on a high speed agitator and blended with the water (2).
Film Properties Drying conditions 25ºC, 50-60 % relative humidity.
Catalyst on Resin Solids No catalyst DBTDL ZIRC B
Zirconium, % ------- ------- 0.008
Tin, % ------- 0.0075 -------
Aged before application, hours 0 0 0
Paint appearance foam foam no foam
Film properties
Tack free (hours) 5 3.5 3.75
Through dry (hours) 8 4.5 4.0
Gloss, 20°, % 53.0 94.7 94.9
Gloss, 60°, % 84.7 99.7 99.9
Catalyst on Resin Solids No catalyst DBTDL ZIRC B
Aged before application, hours 1 1 2
Paint appearance foam 1 hour gel no foam
Film properties
Gloss, 20°, % 75.0 88.3
Gloss, 60°, % 92.4 97.8
Aged before application, hours 4
Paint appearance
foam
Film properties
Gloss, 20°, % 87.4
Gloss, 60°, % 96.2
Maximum potlife (hours)
3 hours no foam
The appearance of the coating from above formulation can be seen in Figure 15. The DBTDL
catalyzed formulation was applied after ½ and hour, the ZIRC B formulation after mixing and after
2 and 4 hours. DBTDL shows gassing in the film and poor flow after only ½ hour and gelled at 1
hour. The ZIRC B formulation is stable for at least 4 hours. The relative humidity during the
application was 50-60 % and the temperature was between 20-25°C. Figure 16 shows the film
appearance at 50 and 70 % humidity for ZIRC B and for DBTDL at 70 % RH. The DBTDL
catalyzed films lose considerable gloss under the 70 % humidity conditions. The ZIRC B catalyzed
film retains almost all the gloss at 70 % RH. At 90 % RH all films are essentially flat.
Figure 15. Film appearance of water-borne two
component coating, film thickness 25 η. Cure conditions
room temperature and relative humidity 50-60%. Catalyst
ZIRC B and DBTDL.
Figure 16. Film appearance water-borne two component
coating, film thickness 25 η. Cure conditions, room
temperature and relative humidity 50 and 70 %, ZIRC B
and DBTDL catalyst.