Acrylic polymers, 1K coating compositions including the same, and multilayer coating systems including a topcoat layer formed from the 1K coating compositions
Acrylic polymers, 1K coating compositions including the same, and multilayer coating systems including a topcoat layer formed from the 1K coating compositions are provided herein. In an embodiment, a 1K coating composition includes an acrylic polymer having a nominal Tg of at least 25° C. and a melamine crosslinker. The acrylic polymer includes a free radical-polymerized backbone and pendant chains bonded thereto. A first pendant chain of the acrylic polymer includes a first segment and a second segment. The first segment includes an ester linkage and a secondary hydroxyl group. The second segment is connected to the first segment and includes an ester linkage and a branched hydrocarbon chain. A second pendant chain of the acrylic polymer includes a primary hydroxyl group or a urethane-containing group formed therefrom.
1. A 1K coating composition comprising:
an acrylic polymer having a nominal Tg of at least 25° C., wherein the acrylic polymer has the following general formula:
wherein:
R 1 is a primary hydroxyalkyl group or a urethane-containing group formed therefrom;
R 2 is a branched alkyl group;
R 3 is chosen from a secondary hydroxyalkyl group, an alkyl group, or a combination thereof;
R 4 is individually chosen from hydrogen or a methyl group;
w, x, and y are each at least 1; and
z is 0 or at least 1; and
a melamine crosslinker.
2. The 1K coating composition of claim 1 , wherein z is at least 1 and R 3 comprises the secondary hydroxyalkyl group.
3. The 1K coating composition of claim 2 , wherein z is at least 2 and R 3 individually comprises the secondary hydroxyalkyl group and the alkyl group.
4. The 1K coating composition of claim 1 , wherein R 1 comprises the urethane-containing group formed from the primary hydroxyalkyl group.
5. The 1K coating composition of claim 4 , wherein R 1 comprises the reaction product of the primary hydroxyalkyl group and a partially-blocked polyisocyanate having at least one free isocyanate group.
6. The 1K coating composition of claim 5 , wherein the partially-blocked polyisocyanate comprises isocyanate groups blocked with a permanent blocking group.
7. The 1K coating composition of claim 5 , wherein the partially-blocked polyisocyanate comprises isocyanate groups blocked with a removable blocking group.
8. The 1K coating composition of claim 1 , wherein the acrylic polymer is present as a species of a resin component, and wherein the resin component further comprises a second acrylic polymer different from the acrylic polymer that has the nominal Tg of at least 25° C.
9. The 1K coating composition of claim 8 , wherein the resin component further comprises a urethane oligomer comprising a urethane-containing backbone.