Aliphatic polyester coating compositions containing tetramethyl cyclobutanediol

A method for applying a thermosetting monocoat coating composition to a substrate comprising:

• I. providing a substrate for coating;
• II. providing a thermosetting monocoat coating composition comprising:
• A. 50 to 90 weight percent, based on the total weight of (A) and (C), of at least one curable, aliphatic polyester, comprising residues of:
• i. hydroxyl component, said hydroxyl component comprising the residues of:
• a. from 5 to 45 mole %, based on the total moles of (a) and (b), of 2,2,4,4-tetraalkylcyclobutane-1,3-diol (TACD);
• b. from 55 to 95 mole % based on the total moles of (a) and (b), of a diol other than TACD;
• and
• c. from 3 to 35 mole %, based on the total moles of (a), (b) and (c), of a polyol;
• ii. a diacid component, said diacid component comprising the residues of:
• d. from 60 to 90 mole %, based on the total moles of the diacids (d) and (e), of an alicyclic diacid;
• and
• e. from 10 to 40 mole %, based on the total moles of the diacids (d) and (e), of an acyclic aliphatic diacid;
• wherein the curable polyester contains diacid residues in an amount of at least 90 mole % of aliphatic diacid residues, based on the total moles of all diacid residues in the curable polyester, and, wherein the curable polyester has a hydroxyl number of 50 to 450 mgKOH/g of polyester, an acid number of 0 to 80 mgKOH/g, and a number average molecular weight of 300 to 10,000 g/mole of polyester;
• B. from 10 to 50 weight percent, based on the total weight of the coating composition, of a solvent other than water;
• and
• C. from 10 to 50 weight percent, based on the total weight of (A) and (C), of a crosslinker comprising an aminoplast and/or isocyanate;
• III. applying said thermosetting monocoat coating composition to said substrate to produce a coated substrate;
• and
• IV. applying heat to the coated substrate to a predetermined temperature and for a predetermined time to produce a cured coating wherein the cured coating has an impact resistance of greater than 35 in.-lb as determined in accordance with ASTM D 2794, wherein said cured coating has a gloss retention, after abrasion, based on ASTM D 6279, of greater than 50%, and wherein said cured coating has a gloss retention, based on SAE J2527, of greater than 85% after 2000 hours.