Curable coating compositions

A coating composition comprising:

• (a) a polymeric resin comprising hydroxyl functional groups;
• (b) a polyisocyanate crosslinker;
• (c) a thiol comprising at least 2 active hydrogen groups,
• wherein the active hydrogen groups comprise a thiol group or a combination of a thiol group and a hydroxyl group, and
• (d) a tin-based catalyst,
• wherein the ratio of the number of moles of thiol to the number of moles of tin is less than or equal to 100:1 and the amount of (d) the tin-based catalyst is less than or equal to 0.25% by weight relative to the total resin solids, and/or
• the ratio of the number of moles of thiol to the number of moles of tin ranges from 3:1 to 50:1 and the amount of (d) the tin-based catalyst is less than or equal to 0.4% by weight relative to the total resin solids;
• and wherein when the coating composition is applied to a substrate and cured, the coating exhibits:
• an appearance of greater than 75 in distinctness of image (DOI), as measured according to ASTM E430, an appearance of not greater than 50 in the shortwave (SW), and a 7 day hardness value of at least 45, as measured according to ASTM D4366-16.