Suggestions and Some Experiences
Typically, DuPont™ Zonyl® powders are added to polyurethanes to improve sliding abrasion resistance without substantially affecting the impact resistance usually associated with polyurethanes. Our results indicate that Zonyl® micropowder concentrations as low as 1-2% can improve sliding abrasion. Zonyl® has been shown to be beneficial for urethanes abased on both polyester diols and polyether diols. In one test with a soft polyurethane (Shore A60), where there was no "hard" segment and sliding abrasion was poor, addition of 10% Zonyl® MP1100 improved NBS abrasion by a factor of 12, and improved DIN abrasion by a factor of 6.
Zonyl® MP1600 was added to a harder (Shore A84) polyurethane, with improvements in NBS abrasion of 15.
Zonyl® MP1600 and Zonyl® MP1100 have been evaluated as polyurethane additives. Zonyl® MP1600 generally is better for this use, since it has a smaller particle size than Zonyl® MP1100. The neutral character of Zonyl® MP1600 is also advantageous, since acidity or alkalinity can substantially affect product preparation and final urethane properties. Zonyl® MP1100 has a greater capability to evolve HF during processing and use, thus favoring Zonyl® MP1600. (Zonyl® MP1100 has a higher number of reactive (carbonyl fluoride) end groups which, in the presence of moisture, can react to release HP.) Zonyl® MP1600 can be used for applications involving food contact (depending on the FDA regulation that is required to be met) whereas Zonyl® MP1100 does not conform to FDA regulations.
Among the property benefits noted from use of the Zonyl® powders is a slight improvement in hydrolysis resistance and improvement in solvent (acetone) resistance. Because Zonyl® is non-burning under most circumstances, flammability of the urethane may be reduced by the addition of the Zonyl®. The Zonyl® will not be adversely affected by ultraviolet radiation.
For aqueous urethane systems, aqueous dispersions of Zonyl® may be the best way to incorporate the Zonyl®.
For non-aqueous systems, the Zonyl® powder was dispersed in the glycol with relative ease, providing the temperature is controlled (50-60°C was used with a "Terathane" polyol or urethane). Use of a vacuum minimizes the moisture present which reduces the potential for reaction.
