US 12,338,321 B2
Medium or high molecular weight polyester powders, powder coating compositions, and processes of making powders
Tom Melnyk, Greenfield, MN (US)
Assigned to SWIMC LLC, Cleveland, OH (US)
Appl. No. 17/270,794
Filed by SWIMC LLC, Cleveland, OH (US)
PCT Filed Aug. 15, 2019, PCT No. PCT/US2019/046651
§ 371(c)(1), (2) Date Feb. 23, 2021,
PCT Pub. No. WO2020/046593, PCT Pub. Date Mar. 5, 2020.
Claims priority of provisional application 62/724,222, filed on Aug. 29, 2018.
Prior Publication US 2021/0261729 A1, Aug. 26, 2021
Int. Cl. C08G 63/90 (2006.01); C08G 63/81 (2006.01); C08G 63/89 (2006.01); C09D 167/02 (2006.01)
CPC C08G 63/90 (2013.01) [C08G 63/81 (2013.01); C08G 63/89 (2013.01); C09D 167/02 (2013.01)] 18 Claims
 
1. A process for preparing a polyester polymer powder comprising a medium molecular weight polyester polymer having a number average molecular weight of 4,000 amu to 7,000 amu or a high molecular weight polyester polymer having a number average molecular weight greater than 7,000 amu, which process comprises:
a) providing or forming an ester oligomer that has a greater acid number than hydroxyl number;
b) converting the oligomer to the polyester polymer by stirring at an elevated temperature a reaction mixture comprising the oligomer and a nonreactive carrier comprising an aromatic hydrocarbon, wherein the elevated temperature is at least 200° C.;
c) removing water from the reaction mixture via azeotropic reflux to provide a syrup comprising a medium or high molecular weight polyester polymer in the nonreactive carrier; and
d) applying a vacuum to form a solid in the form of a powder comprising the medium or high molecular weight polyester polymer;
wherein the polyester polymer has an acid number of at least 17 and up to 26.