| 摘要 |
The invention relates to an additive system for increasing the pot life of two-component, solvent-borne polyurethane coatings; such polyurethane coatings in combination with the additive; as well as a method for increasing pot life based on using the additive in combination with such coatings. The additive is based on a metal catalyst selected from cobalt, manganese or mixtures thereof at from 0.01-0.10% and an organic chelating agent at 0.03-0.5%, all percentages expressed as mass percent of resin solids. Preferred amounts of metal catalyst are about 0.02-0.04% and preferred amounts of chelating agent are about 0.066-0.15%. As it is more preferred to use the least amount of additive, a more preferred additive composition contains about 0.02% metal catalyst and about 0.06-0.08% chelating agent. It is also possible to express the components in terms of a ratio, wherein a preferred composition is between about 1:5 to about 1:20 metal catalyst chelating agent, with a most preferred composition at about 1:3.8
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